Interesting, DOHC vs. Pushrod 500+ HP Engines

[Paul Workman]

I ran across a couple SBC videos of engines claiming to be 500+ hp, and thought it would be interesting to compare to an LT5, just for fun...

http://www.youtube.com/watch?v=05Tc79XywhA&feature=related
http://www.youtube.com/watch?v=StCV0qYdqxU&NR=1

And my 508 hp LT5

http://www.youtube.com/watch?v=y1YFa8ruh8A

Makes for an interesting comparison, I thought.

Took her out to stretch her legs a bit today. Geeeze but that 19 degree air sure makes some wicked hp! Course, the tires didn't grip for crap - no surprise there, I guess.

Happy new year! May your mods go smooth - and long live the King!

Is it spring yet??

P.

[tomtom72]

We used to call them motors that sounded like they were making coffee....that very lumpy idle of the big cam...seemingly shutting off in between each cylinder firing...memories of high school in the late 60's & the smell of SUNOCO 260, leaded of course! :)

On the other hand your motor's idle belies it's potential aggression and the big can of whoop a$$ that it's packing. :handshak: There will proly be a lot of hot car drivers that will rue the day they meet up with your Z Paul!

Curious observation, or perhaps reflection, on my part here. I have a few corvette crusin' buds & they all have 5's & 6's. They are all modded to a degree. I'm the only 'runt' stocker in the pack.

None can get away with "nah, it's bone stock!"....the idle of even an OBDII motor gives away itself. Even a friend's C6/ZO6 at idle doesn't sound like 'docile' if you listen closely. My 72 LT-1 even with side pipes idling @ 900 rpms didn't sound like anything much....pull off the idle assist solenoid and let it idle on the carb & it was a different story @ 450 rpms....an LT5 is the purist stealth weapon, it's so civilized it should be a crime!:mrgreen:

Enjoy her!
:cheers:
Tom

[FU]

I LOVE my LT5's . But your comparing apples to oranges. Long live the KING. Technology moves on.
Ever hear a 505 H/P LS7 idle ?

[Paul Workman]

I LOVE my LT5's . But your comparing apples to oranges. Long live the KING. Technology moves on.
Ever hear a 505 H/P LS7 idle ?

The comparison is apples to oranges only from a technology standpoint, Frank. But displacement to hp is close enough to be equal in both cases, but there is a huge difference in overall drivability, is my point.

IMO, when comparing output of same displacement, I think it was a big mistake for Government Motors to scuttle the DOHC V8 project. It might take something like Ford's 5.0L "Coyote" DOHC motor making over 412 hp to shake some sense back in GM's management. (The Coyote's split plenum & cross ram induction they're using looks a lot like the Katek approach to the C5 and C6Rs.) I just feel GM is being obstinate and obtuse where the future of Corvette is concerned...Not that I wouldn't take a C6 Z06 in a New York second!:cheers::cheers:

P.

[todesengel]

I'll honestly have to go with Frank on this. I will however include videos of my little 700 hp plus cobra 5.0 vert, and 587 hp 4.2l Audi RS4 for your comparison...

http://s13.photobucket.com/albums/a260/chaosrob/?action=view&current=cobrarev.mp4

http://s13.photobucket.com/albums/a260/chaosrob/?action=view&current=audirs4rev.mp4

[Aurora40]

HP/displacement is a ricer argument, in my opinion. No offense is meant by that, it's just that it is a meaningless metric. Displacement doesn't reflect physical size, fuel consumption, or anything really particularly important.

That said, if you want a 400+whp C4 that drives and idles smooth as silk, there is no doubt an LT5 is a great starting point.

[todesengel]

HP/displacement is a ricer argument, in my opinion. No offense is meant by that, it's just that it is a meaningless metric. Displacement doesn't reflect physical size, fuel consumption, or anything really particularly important.

That said, if you want a 400+whp C4 that drives and idles smooth as silk, there is no doubt an LT5 is a great starting point.

Im not going to argue the ricer standpoint, because what I have seen from the board there is not a 350, or 441 for that matter, on here that can bag on my imports (except maybe the Audi, it is my least powerful one, and still runs a 12.1

Choice is a flavor. Some want lumpy cams, big carbs to make power, some a power adder, others a big block punched way out, and still others a quad cam v-8. None of this changes the fact that it is apples to oranges. It is however a perfect example of two different paths to the same goal, and each can make their own personal argument on why theirs is better to THEM.

[Aurora40]

Im not going to argue the ricer standpoint, because what I have seen from the board there is not a 350, or 441 for that matter, on here that can bag on my imports (except maybe the Audi, it is my least powerful one, and still runs a 12.1

Sounds like you took offense. I wasn't suggesting imports can't be fast. Rather, generally speaking the people who care about hp/liter are the ones who don't have much hp.

It isn't a metric that has any real world significance.

[todesengel]

Sounds like you took offense. I wasn't suggesting imports can't be fast. Rather, generally speaking the people who care about hp/liter are the ones who don't have much hp.

It isn't a metric that has any real world significance.

Nope, I didn't take offense at all. Other peoples input, and/or opinions of what I own mean very little to me. if I spent all my time looking for approval, or pleasing others I would have no time to please myself.

My only point is that people build different cars for different reasons. While others may not be able to see the logic behind their build, they do.

An example of this is any car that I build has to have the ability to easily make a cross country trip at a moments notice, while leaving me with all the creature comforts and acceptable fuel economy. My next door neighbor has a 469 bbb chevelle (I think that is waht he said it is stroked to), with a hug cam, manual brakes, manual steering, no air, etc. His car dyno's at 750 ish hp, while I have 3 cars that exceed that, and still meet my criteria.

He wouldn't build a car similar to mine, nor would I build a car like his. Each have their place, just not in the others world.

I will however say the rice card is almost as overplayed anymore as the race card, just mho.

[Kevin]

Im not going to argue the ricer standpoint, because what I have seen from the board there is not a 350, or 441 for that matter, on here that can bag on my imports (except maybe the Audi, it is my least powerful one, and still runs a 12.1

Choice is a flavor. Some want lumpy cams, big carbs to make power, some a power adder, others a big block punched way out, and still others a quad cam v-8. None of this changes the fact that it is apples to oranges. It is however a perfect example of two different paths to the same goal, and each can make their own personal argument on why theirs is better to THEM.

the point, you missed it

[Paul Workman]

the point, you missed it

Yep, they did!:thumbsup:

[todesengel]

The point wasn't missed.

You went on in a post after Franks talking about drivability. The definition of that is going to be based upon a persons own goals, not someone elses.

There are many 500 hp pushrod engines that don't idle like the examples shown.

[tomtom72]

The Mustang would not fool me at a traffic light. I wouldn't have guessed blown & injected....but me & my ZR-1 would know enough to stay away. There is something in the exhaust note...under the usual GT sound....sounds more like a BB at idle. There is too much bass for a stock sb.:)

The Audi on the other hand would have suckered me! It doesn't sound much different than the hundreds of Audis running around where I live. I would have been smoked!:o

Nice machines! :handshak:

:cheers:
Tom

[todesengel]

The Mustang would not fool me at a traffic light. I wouldn't have guessed blown & injected....but me & my ZR-1 would know enough to stay away. There is something in the exhaust note...under the usual GT sound....sounds more like a BB at idle. There is too much bass for a stock sb.:)

The Audi on the other hand would have suckered me! It doesn't sound much different than the hundreds of Audis running around where I live. I would have been smoked!:o

Nice machines! :handshak:

:cheers:
Tom
Thanks Tom.

I cannot keep anything without modding it, and I am a sucker for a sleeper. The audi is as far as I can take it without risk of blowing it to pieces, and I am just not willing to spend the cash on it.

There are many cars on this forum that could take it out, but they better not flub the launch as the awd system work pretty well in that thing. From a roll, not so great.

[Polo-1]

OK time for a LT5 with a little more to it:mrgreen:

http://i7.photobucket.com/albums/y292/kpie/th_MVI_1983.jpg (http://s7.photobucket.com/albums/y292/kpie/?action=view&current=MVI_1983.mp4)

[tomtom72]

more gear head porn...:mrgreen:

LT5 porn to be precise :-D

[todesengel]

OK time for a LT5 with a little more to it:mrgreen:

http://i7.photobucket.com/albums/y292/kpie/th_MVI_1983.jpg (http://s7.photobucket.com/albums/y292/kpie/?action=view&current=MVI_1983.mp4)

sounds f-1'ish. Corsa? I love the way they sound, I just don't think I could handle the drone they supposedly have.

[Polo-1]

Corsa = 0% DRONE

[todesengel]

Corsa = 0% DRONE

good to know. I guess the three people I talked to at Bowling Green with it on their car must have some type of different setup, header, cats, lack of, something different to make them complain about it.

[DDSLT5]

For your listening enjoyment - go to 2:15 or 3:00 for some LT5 fun! :))

http://www.youtube.com/watch?v=ZEXXDKyQPVY

[Paul Workman]

The point wasn't missed.



Oh, oh yes it was missed, but it's my fault for being vague though... But, your SC mustang makes a good point too! (I'm just making conversation here - not impugning anyone, OK?)

What I was obliquely pointing out was, how power is made in view of upcoming restrictions (gas mileage) displacement and efficiency are most certainly going to be relevant for production vehicles. And, cubic inch for cubic inch, the DOHC 4-valve configuration with it's independently and dynamically controlled cams and "lifters" breathes soooo much better and has sooooo much more flexibility and output potential than single cam, OHV designs! The DOHC/4-valve approach - is but one example of why in my gut I feel GM is screwing the pooch by chasing single cam OHV technology any further - at least in the long term. (Course, who knows what is going on behind the curtain in GM's engineering shop?) And, when coupled with a 35 mile/gallon (or more?) in the near future, cubic inches to get hp (a la the LS7) may be a thing of the past. Power/displacement, according to my crystal ball, WILL become a relevant factor if output is to remain steady with efficiency a mandate.

To your supercharger point; that is one option that certainly works in the short term. For you or me, or many (most?) ZR-1 drivers on this board, maintenance of such a setup might not be a factor. But, I'm referring to the unwashed masses of Corvette buyers that are needed if the brand is to survive so we car nuts have the luxury of picking and choosing and playing with the picks of the litter, so to speak. Supercharging has been around since WWII, and even Dave Mclellan fooled around with it back in the 70s. Yet, to the casual observers like us, when it came down to "absolute" reliability and performance, even the Callaway approach - that was readily available to GM - was pushed aside in favor of a "better" power plant scheme for the ZR-1.

Well, I'm not a mechanical engineer, so I'm out on a limb here. But, from where I sit, the evolution of the internal combustion engine, as it applies to the Corvette in particular, took a huge leap forward in the form of the LT5. High performance (piston) aircraft engines and motorcycle engines (opposite ends of engine displacement) are often built with 4+ valves per cylinder, and the aircraft example is built with superchargers to boot; where (in both cases) power efficiency IS a factor. So, was the reason GM shelved the DOHC multi-valve concept (in V8s at least) a failure of technology or just expedient?

There was this company that made oaken buckets. Sales started slipping when home builders began to use pipes to carry water to the houses. So, the oaken bucket company decided to combat slumping sales and make the best quality oaken bucket ever. The best oak, topped off with the finest brass rings and handle were produced. And, for a short time, sales did pick up and the company was assured it had made the right decision.

But, eventually, sales plummeted and the company went broke, in spite of making the finest oaken buckets ever produced. They simply failed to realize that people did not want buckets; they wanted water. The bucket was (at the time) the way to do that. But, technology had moved onto a more efficient method of getting water from the well to the sink.

I don't know if the DOHC 4+-valve NA motor is the answer. But, in my gut I feel GM is making the finest "LSx" oaken buckets ever! (was my point:)).

Pop some popcorn and enjoy the show. The next 5-10 years...are going to be interesting, methinks!!:cheers:

P.

[Aurora40]

I don't know if you mean shelving the LT5, or shelving the premium V8?

Shelving the LT5, it sounds like that may have been the right move for the base Corvette. It's too bad they didn't at least build the '95 engine and have the C4 go out with a huge bang.

I think shelving the premium V8 is a really poor move. I've no idea what Cadillac expects to sell car-wise besides CTS's in the future. With no premium V8, they really will be at a loss in the large lux car market. At this point, even Hyundai has a DOHC V8, and it makes 430hp to boot.

GM had really neglected the Northstar along the way, so it was probably a huge endeavor to update it. Back in 1992, it made 295hp. By the last redesign, 14 years later, it was only up to 330.

[Pete]

To add a couple of things.

The LT5 is about 30 year old technology and with some of todays technics and tricks we see LT5's potential we get up to 450 whp with stock cams very docile N/A on todays crappy pump gas.
Today they do it with 77 more cubes.
Not too shaby for a 30 year old motor.

HP can be made in all sorts of ways and if raw HP is your game bring some CA$H.

Now some of my thoughts, power adders are doing it the easy way it's like "Power for Dummies" book is coming out soon LOL

Also street cars use crappy pump gas, cars that use race gas are just that race cars.
"Show me on 87 octane",i'm from Missouri :)

Now lets take the turbo/power adders out use crappy pump gas again "show me":)

I need to move to Missouri.
My new motto "10's on 87":fahne:

Pete

[todesengel]

Easy way? If that were true you wouldn't have imports, and domestics, popping engines with them every hour.

Careful Pete, you are going to be accused of being a bench racer with your claims of "all things being even".

87 is for lawn mowers, c16 and alcohol is for race cars ;).

The street is run what you brung. When I have your cash in my pocket my wallet doesn't care if i was running 93, 106, 116 or meth injection, it just feels better.

To add a couple of things.

The LT5 is about 30 year old technology and with some of todays technics and tricks we see LT5's potential we get up to 450 whp with stock cams very docile N/A on todays crappy pump gas.
Today they do it with 77 more cubes.
Not too shaby for a 30 year old motor.

HP can be made in all sorts of ways and if raw HP is your game bring some CA$H.

Now some of my thoughts, power adders are doing it the easy way it's like "Power for Dummies" book is coming out soon LOL

Also street cars use crappy pump gas, cars that use race gas are just that race cars.
"Show me on 87 octane",i'm from Missouri :)

Now lets take the turbo/power adders out use crappy pump gas again "show me":)

I need to move to Missouri.
My new motto "10's on 87":fahne:

Pete

[Jim Nolan]

If I can add my .02 worth. I put a Corsa catback system on my '92 and loved it. Now I have SW headers, no cats and full porting and it now sounds like s##t. The Corsa just doesn't, in my opinion, match up very well on a system with headers and no cats.

[Pete]

No,No,No point missed.
30 year old technology
Compared to todays N/A SBC needs more cubes
Heck,Chevy needed to out do themselfs and they went the easy way slaped a Supercharger in it,i would've prefered N/A 500ci

It's not "run what you brung" it's "bring your wallet and hope you have enough" i.e. if i had Trump money i'd buy the fastest cars from NHRA,now tell me how that run what you brung thing works again.:)

My new bumber sticker
ZR-1 Landscaping :-D

Pete



Easy way? If that were true you wouldn't have imports, and domestics, popping engines with them every hour.

Careful Pete, you are going to be accused of being a bench racer with your claims of "all things being even".

87 is for lawn mowers, c16 and alcohol is for race cars ;).

The street is run what you brung. When I have your cash in my pocket my wallet doesn't care if i was running 93, 106, 116 or meth injection, it just feels better.

[todesengel]

No,No,No point missed.
30 year old technology
Compared to todays N/A SBC needs more cubes
Heck,Chevy needed to out do themselfs and they went the easy way slaped a Supercharger in it,i would've prefered N/A 500ci

It's not "run what you brung" it's "bring your wallet and hope you have enough" i.e. if i had Trump money i'd buy the fastest cars from NHRA,now tell me how that run what you brung thing works again.:)

My new bumber sticker
ZR-1 Landscaping :-D

PeteLol, yup, completely missed your point, BUT racing is usually about who has the bigger wallet. There are shoestring winners here and there, but building a fast car requires two things, as a rule, thinking outside the box, and money
Cheap, fast, reliable....pick two

[FU]

For your listening enjoyment - go to 2:15 or 3:00 for some LT5 fun! :))

http://www.youtube.com/watch?v=ZEXXDKyQPVY

THAT SOUNDS UNBELIEVABLE ! No pushrod engine screams like that ! =D>

[Paul Workman]

THAT SOUNDS UNBELIEVABLE ! No pushrod engine screams like that ! =D>

Dittos, Frank! Oooo, yeah! Gives me goose bumps!

It is interesting to see the heads turn and the :jawdrop: when one of ours hits that "high note" at a dyno day, or the dismay on some faces when Pete's Green Monster sucks the paint off the door of a C6 Z06 driver...(heh, heh, heh.... :)

Is it spring yet?

P.

[FU]

Is it spring yet?


Spring couldn't come soon enough for me.

[todesengel]

Spring couldn't come soon enough for me.

I will be up in MD, and NJ next week. I am not looking forward to sharing your weather.

[Pete]

Spring couldn't come soon enough for me.

4 months BG :-D

Rob,why do you drive to cold places go to nice warm places.

Pete

[Hog]

I don't know if you mean shelving the LT5, or shelving the premium V8?

Shelving the LT5, it sounds like that may have been the right move for the base Corvette. It's too bad they didn't at least build the '95 engine and have the C4 go out with a huge bang.

I think shelving the premium V8 is a really poor move. I've no idea what Cadillac expects to sell car-wise besides CTS's in the future. With no premium V8, they really will be at a loss in the large lux car market. At this point, even Hyundai has a DOHC V8, and it makes 430hp to boot.

GM had really neglected the Northstar along the way, so it was probably a huge endeavor to update it. Back in 1992, it made 295hp. By the last redesign, 14 years later, it was only up to 330.
The Northstar did have its 443hp and 469hp flavours in the XLR-V and STS-V, and those engines were rated using the SAE J1349 "Certified Power" rating system. These 2 engines identical, but the intake and exhausts differ, as does the calibration I assume.

Only the 2010 LH2 4.6 busted over the 300hp hump with 320hp@6400rpm/315 lb/ft@4400rpm using VVT in the STS.

LD8 275hp@6000rpm/295 lb/ft @ 4400rpm in the Caddy DTS.

L37 is 292hp@6300rpm/288 lb/ft@4500rpm in the Caddy DTS


I would like to go back and see what your 295 hp Northstar and what my 300hp Northstar would put out using the newer "Certified Power", I would be more curious to see what the 375hp and 405 hp LT5's actually output.

peace
Hog

[todesengel]

4 months BG :-D

Rob,why do you drive to cold places go to nice warm places.

Pete

If I could, I would. I typically send my guys to the warmer places, and I myself go where nobody really wants to lol.

BTW, I got one package from Jerry yesterday, and should get the other today. I will forwrd it to you as soon as it gets here

[Aurora40]

The Northstar did have its 443hp and 469hp flavours in the XLR-V and STS-V, and those engines were rated using the SAE J1349 "Certified Power" rating system. These 2 engines identical, but the intake and exhausts differ, as does the calibration I assume.

Only the 2010 LH2 4.6 busted over the 300hp hump with 320hp@6400rpm/315 lb/ft@4400rpm using VVT in the STS.

LD8 275hp@6000rpm/295 lb/ft @ 4400rpm in the Caddy DTS.

L37 is 292hp@6300rpm/288 lb/ft@4500rpm in the Caddy DTS


I would like to go back and see what your 295 hp Northstar and what my 300hp Northstar would put out using the newer "Certified Power", I would be more curious to see what the 375hp and 405 hp LT5's actually output.

peace
Hog
The RWD Northstar came out in 2005, and made 320hp. The "V" Northstar was supercharged, not really an evolution of the engine.

You can see what the 300hp L37 made using certified power, as it was still in production after GM made the switch. It dropped about 10-15hp if I recall.

Anyway, I'm not sure what you are getting at. Do you think the Northstar has been continually evolved to keep on top of the competition? What is your contention?

[Hog]

The RWD Northstar came out in 2005, and made 320hp. The "V" Northstar was supercharged, not really an evolution of the engine.

You can see what the 300hp L37 made using certified power, as it was still in production after GM made the switch. It dropped about 10-15hp if I recall.

Anyway, I'm not sure what you are getting at. Do you think the Northstar has been continually evolved to keep on top of the competition? What is your contention?
You stated that the Northstar output was "only 330hp" after its ?? year production run. I was simply stating that there were Northstar engine that outputted much more than that.
Then I proceeded to show what the last of the Premium V8's was outputting in it's last year of production.

The 2006 L37 that was rated using certified power is different than my older 1998 L37. They would have different outputs, as the camshaft specs are different. In 2004 it was rated at 300hp, in 2006 it was rated at 292 SAE "certified".

To answer your question, no I dont think the Northstar was continually evolved to stay on top of the competition. The only attempt at staying on top of the competition was the introduction of the "V" series 4.4l SC engines. Most of the engineering changes were to help to fix issues with the engine, or to enhance fuel economy/emissions. Other than the supercharged LC3 engine, little was done to add power in any significant way.

peace
Hog

[Aurora40]

The 2006 L37 that was rated using certified power is different than my older 1998 L37. They would have different outputs, as the camshaft specs are different. In 2004 it was rated at 300hp, in 2006 it was rated at 292 SAE "certified".

The FWD engine was "significantly" redesigned for the 2000 model year. That engine also made 300hp in L37 trim. And that motor was eventually tested under the new SAE procedures. You are correct, they obviously never retested the 1992-1999 motor.

While they changed like 80% of the parts, had a better intake, faster burning heads, a more powerful PCM, for the 2000 redesign, they still didn't crank up the output any higher. I've no idea why they made such a complete change to the motor, and had as their only real goal to let it run on regular unleaded.

They had an opportunity again with the RWD Northstar, and bumped the power up a measly 20. I never understood why they were so content to let the Northstar fade away like that. When it first came out, it was widely hailed, and quite potent compared to the competition. Then it pretty much just coasted for 18 years until they killed it.

I don't really consider the S/C Northstar to be relevant. It was hand-built and low volume. It never would have been viable from both a cost and a size standpoint in most of GM's cars. But you are technically correct, they did have one specific large bump in power. I think an S/C Northstar would be a pretty sweet motor, though I confess I'd be scared to own one long-term.

[Kevin]

The point wasn't missed.

You went on in a post after Franks talking about drivability. The definition of that is going to be based upon a persons own goals, not someone elses.

There are many 500 hp pushrod engines that don't idle like the examples shown.

you're still missing the point. the only people who talk about hp/l are the ones who's cars aren't fast but the owners like to think they are. aka ricers

[todesengel]

you're still missing the point. the only people who talk about hp/l are the ones who's cars aren't fast but the owners like to think they are. aka ricers

f1 car designers are ricers? Exotics are ricers? Apparently they fall in line with your reasoning since the make a huge point of hp/l.

It never ceases to amaze me how people just throw that word around. I, like the exotic, f1 crowd am also a ricer I guess. I can also state that big cubes don't scare any of my imports. Refer to me however you like, I am very comfortable in my skin, so so continue with your "point"

[Kevin]

f1 car designers are ricers? Exotics are ricers? Apparently they fall in line with your reasoning since the make a huge point of hp/l.

It never ceases to amaze me how people just throw that word around. I, like the exotic, f1 crowd am also a ricer I guess. I can also state that big cubes don't scare any of my imports. Refer to me however you like, I am very comfortable in my skin, so so continue with your "point"

i've never heard anyone talk about hp/l other then people who put a 5" exhaust tip on a civic. I don't know why you're taking this so personally, we get it you own imports, guess what so do most of us here. Seems like you need to get over yourself a bit

[todesengel]

i've never heard anyone talk about hp/l other then people who put a 5" exhaust tip on a civic. I don't know why you're taking this so personally, we get it you own imports, guess what so do most of us here. Seems like you need to get over yourself a bit

You referenced me in your quote, and just decided to throw what you obviously consider a derogatory term my way in response, yet I need to get over myself?

The slowest sports car I had in my stable was my 465 hp lingenfelter zr-1, until I gave it to my 17 year old son. Yet because you feel any discussion that refers to hp/l is only introduced by a "ricer".

If you are hanging around with kids that own civics with 5" fart cans on them, and want to throw every import car in with them, so be it. I wouldn't however expect to post that and not expect a response. Not because I take it personally, but simply because it is wrong.

[Pete]

Boy Boys.
It's not ricers that compare HP/L.
It's the whole world but the USA.
Just like metric and standard i think we're the only country using standard.
I would've had a smaller tool box if we had one measurement.

I think the reason we don't use HP/Lis we don't care about HP/L we stuff the biggest motor/cam in our cars,if it feels good on our butt dyno that's all that matters,at least that's all that matters to me :)

Pete

[Kevin]

You referenced me in your quote, and just decided to throw what you obviously consider a derogatory term my way in response, yet I need to get over myself?

The slowest sports car I had in my stable was my 465 hp lingenfelter zr-1, until I gave it to my 17 year old son. Yet because you feel any discussion that refers to hp/l is only introduced by a "ricer".

If you are hanging around with kids that own civics with 5" fart cans on them, and want to throw every import car in with them, so be it. I wouldn't however expect to post that and not expect a response. Not because I take it personally, but simply because it is wrong.

actually if you go back and read the thread you'll see that i'm not the one that started the first used the ricer term, but if you want to direct your anger at me go head, I got nothing better to do with my time. Secondly I don't really care where a car was made, if it's a quality car I'm generally going to like it...though i do have a thing against german cars

[Paul Workman]

Well, actually I was the one alluding to hp/l as a metric US manufactures are going to be forced to look at pretty soon as mpg requirements get tighter and tighter. All out racing is "whatever works", but mpg and passing emissions standards is not a concern. So, when one does start looking at hp/l and passing emissions (a la production cars) it generally isn't the OHV motors you see making the big numbers.

I'm just saying hp/l is going to be a factor in the not so distant future and I happen to believe that it was a mistake for GM to (apparently) shelve the DOHC V8 development in favor of displacement for NA motors - albeit a shining example of modern OHV engineering. The LSx = "Oaken buckets"... I fear, whose days are perhaps numbered - at least where the future of Corvette is concerned. I promise ya, I won't likely be getting in line to buy a FI pushrod V6 in the C7 Vette, if that is what they have in mind!

Gotta run.

P.

[Aurora40]

Wow... You really can't seem to not take offence, or tout how fast your cars are.

F1 cars make a lot of horsepower. Their engines are pretty interesting. That said, they are only small because they are required to be. If F1 had open engine specs, I doubt very many teams would build a 2.8L V8 that revved to 18,000 RPM. It's not because they value hp/liter that F1 cars are the way they are. They value horsepower, and there is a cap on displacement. In fact, you can look back in time to CanAm. When companies like Ferrari would run their small F1 engines, they'd get it handed to them. To win, you wanted the most power, not the most power/displacement.

Pete, much of the rest of the world cares because historically they have been taxed on displacement. So if you want decent horsepower, and don't want to pay thousands in taxes when you buy your car, you want something with high power/displacement. Now that most of the EU taxes cars based on carbon dioxide emissions, I wonder if you will see engines get slowly larger?

Your Audi makes 587hp. That's a lot, whether it's from 4.2L, 5.2L, or 20L of engine. As long as it fits under the hood and has the driveability you want, who gives a crap what its hp/liter is?

I think Paul's oaken bucket thing is far afield from reality. The fact that an LSx has lower hp/liter than the LT5 means little, in my opinion. It doesn't make the LT5 "better" just because it makes more hp/liter than an LS motor. And it doesn't take more effort to drive a pushrod motor vs OHC, like it takes to get water from a bucket vs plumbing.

That said, the LT5 is pretty great. With not a lot of work, they can put down 400-440whp from a stock bottom end, and still drive and idle like a stocker. What's not to like about that?

Edit: To be less contentious, can you explain to me the value of hp/liter? If all of your cars made exactly the same power as they do now, drove the same, got the same economy, and the engines were the same physical size, but they were all exactly one liter larger in displacement. What exactly would be the effect? What would be different? How would a change to nothing other than the hp/liter number change your car?

[todesengel]

Wow... You really can't seem to not take offence, or tout how fast your cars are.

F1 cars make a lot of horsepower. Their engines are pretty interesting. That said, they are only small because they are required to be. If F1 had open engine specs, I doubt very many teams would build a 2.8L V8 that revved to 18,000 RPM. It's not because they value hp/liter that F1 cars are the way they are. They value horsepower, and there is a cap on displacement. In fact, you can look back in time to CanAm. When companies like Ferrari would run their small F1 engines, they'd get it handed to them. To win, you wanted the most power, not the most power/displacement.

Pete, much of the rest of the world cares because historically they have been taxed on displacement. So if you want decent horsepower, and don't want to pay thousands in taxes when you buy your car, you want something with high power/displacement. Now that most of the EU taxes cars based on carbon dioxide emissions, I wonder if you will see engines get slowly larger?

Your Audi makes 587hp. That's a lot, whether it's from 4.2L, 5.2L, or 20L of engine. As long as it fits under the hood and has the driveability you want, who gives a crap what its hp/liter is?

I think Paul's oaken bucket thing is far afield from reality. The fact that an LSx has lower hp/liter than the LT5 means little, in my opinion. It doesn't make the LT5 "better" just because it makes more hp/liter than an LS motor. And it doesn't take more effort to drive a pushrod motor vs OHC, like it takes to get water from a bucket vs plumbing.

That said, the LT5 is pretty great. With not a lot of work, they can put down 400-440whp from a stock bottom end, and still drive and idle like a stocker. What's not to like about that?

Edit: To be less contentious, can you explain to me the value of hp/liter? If all of your cars made exactly the same power as they do now, drove the same, got the same economy, and the engines were the same physical size, but they were all exactly one liter larger in displacement. What exactly would be the effect? What would be different? How would a change to nothing other than the hp/liter number change your car?

Well let's go ahead and flip this. The only people on a car site I have ever seen complain about someone else describing what they have are either jealous, or slow, which one applies to you? Does that argument make sense? To me it makes about as much sense as throwing a label on someone else because they happen to bring technology into the discussion, which wasn't even me to begin with.

You mistake a counter point for taking things personally. You people, like I to you, strangers somewhere behind a keyboard posting messages. I don't support you, sleep with you, eat dinner with you, or share living quarters with you, so why would I take anything you have to say personally?

If I didn't think the lt-5 was a great power plant, why would I be here? If I didn't believe it had potential, why would I choose to put it into a different platform?

The part I will always dispute is putting labels on people, I simply do not agree with it. Car people are car people, and they drive what they can afford, and generally do what they can. Anyone who puts time, and energy into what they own are generally proud. Just because someone else does not agree with how they spent their money they feel they can throw a label on them, I guess so they can feel better about what they own *shrug*.

To your question about hp/l, if an engine is one liter larger, physically the same size, and made the same power it means it is less efficient. I cannot speak for everyone who is a "gear head", but I am all about maximizing the full potential of a powerplant, and wringing every bit of hp out of it I can afford to, without making it unreliable. To me it is a lot like investments. If you could invest 100k to get a yearly return of 5k, or 50k to get the same yearly return, which would you choose? If you have a wife, would you rather have one that weighs 110 lbs, or 300 lbs? Make two identical parts, but one process requires 100lbs of material, and the other 50 lbs to achieve the same result.

Efficiency is as important as the end product, imho. If you are not concerned with it, I am ok with it, why are you not ok with the path I choose?

[todesengel]

actually if you go back and read the thread you'll see that i'm not the one that started the first used the ricer term, but if you want to direct your anger at me go head, I got nothing better to do with my time. Secondly I don't really care where a car was made, if it's a quality car I'm generally going to like it...though i do have a thing against german cars

I'm not angry Kevin, just offering a counter point. While it may be difficult to read emotion through the typed word on a website, I do not believe I have exhibited signs of anger. I have not resorted to name calling, and belittlement, but others have.

[Paul Workman]

Edit: To be less contentious, can you explain to me the value of hp/liter? If all of your cars made exactly the same power as they do now, drove the same, got the same economy, and the engines were the same physical size, but they were all exactly one liter larger in displacement. What exactly would be the effect? What would be different? How would a change to nothing other than the hp/liter number change your car?

The underlying supposition is fuel economy AND hp being the elements in the equation. But, those are some pretty big "IFs" thar! IF the same power, IF they drove the same, IF they get the same economy, IF they are the same physical size...Then hp/l would not be a factor. But, is that possible?

As far as oaken buckets go, I'm simply saying manufactures (GM) have to be careful not to become enamored with a particular technolgy and become over-committed. Is GM over-committed to the LS "solution"? I think they are. But, that's just IMO. Looking back at 50+ years of evolution of the Corvette, NOT ALL of it has been wonderful at times, and they again are stubbornly sticking with their current solution while others are going different routes. Time and future requirements will tell. But, I'm betting DOHC will win out if future Corvettes (GM) survives. But...who knows.

P.

[Paul Workman]

OK y'all...We're just having a discussion - separating the truth from fiction is what I wuz hopin for..K?

Well, just to toss another potato into the stew, when it comes down to it, PEAK torque or hp is what sells cars, but the real truth is "the area under the curve".

My expertise (if I have any) is in electronics. And, when referring to the actual power contained in a voltage waveform, the dipstick commonly used to quantify it is "RMS" (Root-Mean (of the voltage readings havining been) Squared). I don't know if there is the equivelant in mechanical engineering, but perhaps one of you legit MEs can shed some light on the "power under the curve" question. Just another tool for a closer look at characteristics of the different designs.

Any takers?? I'd really like to be able to quantify power under the curve in the correct manner, if possible. Curiosity is a daaaaanerous thing!!:icon_scra

P.

[Paul Workman]

If you have a wife, would you rather have one that weighs 110 lbs, or 300 lbs?

Well, assuming they both had the same "output" (a BIG IF), that would depend on which one was the higher maintenance, I recon!:dancing

[todesengel]

Well, assuming they both had the same "output" (a BIG IF), that would depend on which one was the higher maintenance, I recon!:dancing
well, it may be a big if, but it is more possible than the engine posted scenario.

I will bow out now so the big kids can talk and keep it civil :wave:

[Aurora40]

To your question about hp/l, if an engine is one liter larger, physically the same size, and made the same power it means it is less efficient.
Efficiency requires something to be used, and low efficiency means something is being squandered. What is that thing in the case of low hp/liter?

hp/liter doesn't relate to fuel efficiency, nor does it relate to power/mass or power/physical size.

Is "displacement" a thing that needs to be conserved or carefully consumed? Can we run out of it?

[Aurora40]

The underlying supposition is fuel economy AND hp being the elements in the equation. But, those are some pretty big "IFs" thar! IF the same power, IF they drove the same, IF they get the same economy, IF they are the same physical size...Then hp/l would not be a factor. But, is that possible?
There are tons of examples of smaller displacement not translating to smaller size, or better economy.

One of GM's, and supposedly the auto industry's, most efficient engines in terms of brake specific fuel consumption, was the "lowly" Buick V6. It's an ancient design that was often criticized for being of large displacement and old pushrod technology compared to its peers. In the late 90's it made about 200hp from 3.8L when Honda and Toyota were making that from 3.0-3.5L engines.

Was it less efficient? No. Was it less powerful? No. Was it heavier or larger? No. It just had more displacement. It also was a hell of a lot cheaper. People viewed it as inferior, and that matters for sales. The engine is gone now.

Look at the LS4 vs the FWD Northstar. The 303hp 5.3L LS4 gets substantially better fuel economy than the 300hp 4.6L L37, and it is small enough to fit in W-body/midsize cars. The Northstar could only fit in full size cars. Unfortunately they were never in the same car for a direct EPA economy comparison, but a look at a Bonnie GXP (probably the lightest car to get the N*) to something like a Buick LaCrosse Super (the largest car to get the LS4) and it is no contest.

It is not a big "If" to have a larger displacement engine that makes the same power as a smaller displacement one, while still having similar economy, size, and weight. DOHC setups are physically large and heavy. You may be able to do more with less displacement, but why do you need to? Take the space you saved in head size and turn it into displacement.

In spite of the low power/weight of something like the LS1/2/3/7, you would be hard-pressed to name a "smaller" production engine that makes the same amount of power as it, is lighter and physically smaller, and uses fuel as efficiently.

[Paul Workman]

There are tons of examples of smaller displacement not translating to smaller size, or better economy.

One of GM's, and supposedly the auto industry's, most efficient engines in terms of brake specific fuel consumption, was the "lowly" Buick V6. It's an ancient design that was often criticized for being of large displacement and old pushrod technology compared to its peers. In the late 90's it made about 200hp from 3.8L when Honda and Toyota were making that from 3.0-3.5L engines.

Was it less efficient? No. Was it less powerful? No. Was it heavier or larger? No. It just had more displacement. It also was a hell of a lot cheaper. People viewed it as inferior, and that matters for sales. The engine is gone now.

Look at the LS4 vs the FWD Northstar. The 303hp 5.3L LS4 gets substantially better fuel economy than the 300hp 4.6L L37, and it is small enough to fit in W-body/midsize cars. The Northstar could only fit in full size cars. Unfortunately they were never in the same car for a direct EPA economy comparison, but a look at a Bonnie GXP (probably the lightest car to get the N*) to something like a Buick LaCrosse Super (the largest car to get the LS4) and it is no contest.

It is not a big "If" to have a larger displacement engine that makes the same power as a smaller displacement one, while still having similar economy, size, and weight. DOHC setups are physically large and heavy. You may be able to do more with less displacement, but why do you need to? Take the space you saved in head size and turn it into displacement.

In spite of the low power/weight of something like the LS1/2/3/7, you would be hard-pressed to name a "smaller" production engine that makes the same amount of power as it, is lighter and physically smaller, and uses fuel as efficiently.

Well, without casting dispersions, this thread has evolved to become less of an engineering epiphany than it has a morass of anecdotal meanderings. Interesting points have been made by you and other, to be sure. But some hard core engineering stuff is needed here - must go find some.

In the mean time, whenever a car "sucks the paint off" when it passes another, or some NA 500 hp engine delivers 35-40 mpg and has stop and go manners and meets emissions requirements - make a note.

gotta run

P.

[Aurora40]

less of an engineering epiphany

Considering production car engines are designed around numerous compromises, I don't think you'll ever have an epiphany of engineering that states one engine design is unequivocally better than the rest.

[tpepmeie]

Didn't plan to jump into this thread, but....

One way race engines of various sizes and types are compared in the industry is BMEP (Brake Mean Effective Pressure). BMEP is often used as a measure of how well developed / efficient the engine is.

The equation is
BMEP = 150.8 x TORQUE (lb-ft) / DISPLACEMENT (ci)

This is typically compared at peak power RPM, although can be used at peak torque as well. The torque value is as measured at the crankshaft. It is essentially "hp per liter, per rpm", and reflects volumetric, thermal, and mechanical efficiencies in a single yardstick.

I wrote an article years ago which was never published in the newsletter comparing the LT5 to various other production engines.

More info here... http://www.epi-eng.com/piston_engine_technology/bmep_performance_yardstick.htm

But as some have pointed out, racing engines are constrained by rules, so efficiency can be an important differentiator. On the street, shear power usually results in more fun (to hell with efficiency, right?) :cheers:

[Jagdpanzer]

Todd,
Please send me the article you wrote.

[Jagdpanzer]

Generally speaking for modern naturally aspirate four cycle gasoline engine designs BMEP numbers in the range of 200-215 psi (14-15 bar) is as good as it will ever get. However, let's not confuse high BMEP numbers with total efficiency. Multivalve overhead cam engine designs coming out today are more fuel efficient per unit of power produced, especially when considering emission regulations that production engines must also meet. Together with the latest developments in direct fuel injection and engine management hardware/software systems, the overhead cam engine design affords better conditions for the combustion process within the cylinder and also achieve lower "pumping" and internal mechanical losses compared to pushrod engine designs of comparable power output.

[tpepmeie]

Generally speaking for modern naturally aspirate four cycle gasoline engine designs BMEP numbers in the range of 200-215 psi (14-15 bar) is as good as it will ever get.

Highest I'm aware of was the Super Touring cars in the 90's, early 2000's. Rev limited, so high BMEP was the only way to make competitive power. 17 bar (246 psi) not uncommon there. Have to do the math, but 330 hp, 2 liters, 8500 rpm. The old Cosworth AC F3000 was 500hp/3L/9000 rpm=16.5 bar. This kind of development is usually only present in rev-limited classes... otherwise, it's easier to chase higher revs for more power.


However, let's not confuse high BMEP numbers with total efficiency.

Not sure I follow you here.

Multivalve overhead cam engine designs coming out today are more fuel efficient per unit of power produced, especially when considering emission regulations that production engines must also meet. Together with the latest developments in direct fuel injection and engine management hardware/software systems, the overhead cam engine design affords better conditions for the combustion process within the cylinder and also achieve lower "pumping" and internal mechanical losses compared to pushrod engine designs of comparable power output.

All true. Breathing (VE), Burning (TE), Friction (ME) are the key ingredients. I was lumping pumping losses in with Friction out of convenience, but you are right it is an important variable.

[Paul Workman]

Thanks for the link, Todd. That link, and others contained therein, supply a lot of useful information for frustrated mechanical engineers like me. After getting more familiar with the information contained there, I can perhaps graduate from "smart azz" to "intelligent posterior" maybe?? - (Then I could be really be dangerous!:) )

Obviously, you have pondered engine design waaaaay beyond that of all but the most devout enthusiasts; save maybe for an automotive engineer (such as yourself). You've made a significant investment in time, testing and materials for the LT5 project. I'd be curious as to what engineering characteristics and or potentials made you decide to explore the LT5 further, rather than some other platform?

I hope to get to meet you at BG this spring. If you wanted to hold court on your 427 project, I'm sure you could pack the auditorium. I know I'd be there in the front row, as would most of the FBI gang.

P.

[tomtom72]

I would also like to thank you very much for the link Todd!:thumbsup:

I'm going to start at the beginning & read fwd to the one you posted.....this is very cool stuff for guys like me that don't know all that much. Great teaching tool! Thank You!

:cheers:
Tom

I would love for an issue of the HOTB to have your article....I may not get it straight away, but I would love to have the chance to read it.