LS7 vs. 350 ci LT5 mods

[Paul Workman]

Finally broke down and bought a new HP document scanner to replace the one that died. So, for your viewing pleasure, a comparision of dyno results for the LS7 vs a couple 350 ci LT5s. Interesting...

First the base C6 Z06 w/ LS7:

http://i185.photobucket.com/albums/x220/6PPC_bucket/tech%20files/DynoC6Z06baseline.jpg

From a couple years ago, I found this in the archives - Don's car (mods unknown) and Dominic's having the top end ported and ??? (he'll have to say what else). (He has a dyno sheet showing close to 400 RWHP after his last tune before he decided to widen the track by trying to push the guard rails out a little wider with his car:razz: (I recon when he gets it running again with the S-II cams and now fully ported, another FBI tire-smoker will be terrorizing the blacktops 'round here!)

http://i185.photobucket.com/albums/x220/6PPC_bucket/tech%20files/Don-DominicDynoCompar1A.jpg

And, (as promised) this is my 350 LT5, fully (FBI) ported and tuned. What interesting machines these LT5s are!

http://i185.photobucket.com/albums/x220/6PPC_bucket/tech%20files/DynoLT510-19-10.jpg

I couldn't find any dyno sheets for some 415s, or 427 or 441 LT5s. But, if someone has one/some, and can post them for comparison, that would be cool!

P.

[Demps]

HAT 415, stock valves, LPE B Cams

http://i148.photobucket.com/albums/s27/demps_photos/Teds415.jpg

Ted

[Kb7tif]

Looks like the lowend torque and lowend power are better on the Ls7
I would hope.
Haibeck has dyno charts of maxed out 415's on the site (destroys the LS7). :-({|=

[USAFPILOT]

Lets see the cost of an LS7 vs anyone's 415. I know 06 Z06's are going for under 40K now on a regular basis. To send my ZR-1 to LPE for a 415 conversion is 29K. I paid 29K for the car a few years ago, so I would have nearly 60K in it. I would be happier with the 415, but the LS7 is looking like a sweet deal these days.

What interests me the most about this is our 350 can get close to the output of the LS7. That is what I am personally shooting for. I want to build the most powerful 350 I can. I should say, one day I will have Corey H do it for me though. I am no engine builder.

[rhipsher]

The thing I've always wanted to know about the 415 strokers from the owners are how tough are they when pushed on a regular basis. Or have the owners of them driven the enough to find out. I don't mean mildly driving. I mean at the drag strip or road racing them. I have a feeling they aren't driven very often. But id like to know from the owners of them.

[XfireZ51]

Lets see the cost of an LS7 vs anyone's 415. I know 06 Z06's are going for under 40K now on a regular basis. To send my ZR-1 to LPE for a 415 conversion is 29K. I paid 29K for the car a few years ago, so I would have nearly 60K in it. I would be happier with the 415, but the LS7 is looking like a sweet deal these days.

What interests me the most about this is our 350 can get close to the output of the LS7. That is what I am personally shooting for. I want to build the most powerful 350 I can. I should say, one day I will have Corey H do it for me though. I am no engine builder.

Just ask Pete to build you a copy of his motor. I'm looking to have a very respectable street car with similar hp to a C6 Z. Something that can hold its own with the new firepower coming from Dearborn, Warren, and Auburn Hills, Michigan.

[Paul Workman]

Lets see the cost of an LS7 vs anyone's 415. I know 06 Z06's are going for under 40K now on a regular basis. To send my ZR-1 to LPE for a 415 conversion is 29K. I paid 29K for the car a few years ago, so I would have nearly 60K in it. I would be happier with the 415, but the LS7 is looking like a sweet deal these days.

What interests me the most about this is our 350 can get close to the output of the LS7. That is what I am personally shooting for. I want to build the most powerful 350 I can. I should say, one day I will have Corey H do it for me though. I am no engine builder.

Not taking anything away from the C6 Z06 - I'll bet with its weight it would be a hoot to drive. But, back to big motors, I believe FBI'ers - Bob G, Al, and Kevin all built a 427, and two 441 LT5s - all of which would blow an LS7 away across the board. And, the tag was more like $20k - quite a bit less if you did your own porting and disassembly and reassembly.

The nice thing about building a big inch LT5 is much of it can be done in phases - providing some nice performance boosts along the way: porting the top end and timing the cams, and installing headers, for example, could net you a 500 hp 350. All those base pieces would transfer to the big boy (with some further porting and bigger valves, perhaps) so nothing is lost. With the sleeves and portability of parts, the LT5 becomes close to "modular"!

Sorry...My enthusiasm is leaking out again:redface:

P.

[FU]

415 12:5 compression
http://i172.photobucket.com/albums/w37/furbo_2007/Franks415.jpg
441 11:1 compression
http://i172.photobucket.com/albums/w37/furbo_2007/Franks440c.jpg
LS7 11:1 compression with headers. Same car with a very small cam 518rwhp 473rwtq
http://i172.photobucket.com/albums/w37/furbo_2007/franku002.jpg

[Aurora40]

Not really a fair comparison, is it? A stock bottom-end LS7 can put down 580-600whp when comparing like mods of intakes, heads, exhaust, and cams.

Not to mention for around $7k you can just drop a maggie on an LS7 and make ridiculous torque and horsepower with no loss of driveability.

[Kevin]

Not taking anything away from the C6 Z06 - I'll bet with its weight it would be a hoot to drive. But, back to big motors, I believe FBI'ers - Bob G, Al, and Kevin all built a 427, and two 441 LT5s - all of which would blow an LS7 away across the board. And, the tag was more like $20k - quite a bit less if you did your own porting and disassembly and reassembly.

The nice thing about building a big inch LT5 is much of it can be done in phases - providing some nice performance boosts along the way: porting the top end and timing the cams, and installing headers, for example, could net you a 500 hp 350. All those base pieces would transfer to the big boy (with some further porting and bigger valves, perhaps) so nothing is lost. With the sleeves and portability of parts, the LT5 becomes close to "modular"!

Sorry...My enthusiasm is leaking out again:redface:

P.

I would hope that a heavily modded car will be faster then a stock car. I love the ZR-1 but modding it is becoming cost prohibitive. $10,000 to get mid 400 hp is insane

[XfireZ51]

No doubt in my mind that $4$, the LS7 is hard to beat for mods. You start out at 505hp, headers and a tune and you're looking 550 at the crank. I have a friend with a Silver 07 Z in that configuration. Not to mention it looks like a Great White coming up on your 6 when viewed in the rearview mirror. For a 5.7L, the LT-5 responds incredibly well to even small mods like porting and better exhaust. So the potential is there but the
OHV v OHC differential will always be low end torque which the LS-7 has in spades. Of course, we'll need to see what Todd has cooked up with his 427. :-D

[Paul Workman]

It is becoming obvious that the torque curves on the LT5s are characteristically flatter over all, and especially at the high end. (See how for the most part the LT5s hp is more or less flat going into 7000 rpm, even on stock cams?)

The trouble with "peak" hp and torque numbers is, well, they're "peaky". The greater area under the curve(s) makes more sense when evaluating usable output.

Just food for thought.

P.

[Kevin]

anyone have dynos of 368 or 385 cars?

[XfireZ51]

It is becoming obvious that the torque curves on the LT5s are characteristically flatter over all, and especially at the high end. (See how for the most part the LT5s hp is more or less flat going into 7000 rpm, even on stock cams?)

The trouble with "peak" hp and torque numbers is, well, they're "peaky". The greater area under the curve(s) makes more sense when evaluating usable output.

Just food for thought.

P.

But Paul, the LS7 doesn't drop down to our level of torque until 7K. Up to then, its always higher than the LT-5.

[Locobob]

anyone have dynos of 368 or 385 cars?

LPE 368

The pull with the higher peak numbers is the result of more aggressive plenum and injector housing porting along with installing an SRP underdrive pulley set.
As you can see the power curve generally moved upward with the loss of some low end torque... as one would expect from a more aggressive intake tract.

http://i418.photobucket.com/albums/pp270/locobob68/Dyno%20runs/368dyno2-06vs4-05aftertune.jpg

[Locobob]

This one is a comparison of mildly modded engines of similar power showing the area under the curve for a 4th gear pull (speed not rpm graph). Anyhow you can see that the LT-5 HP curve is flatter than a comparable power LS-1.


http://i418.photobucket.com/albums/pp270/locobob68/Dyno%20runs/LT5vsLS1.jpg

[Locobob]

Frank: Why is your 441 only 11-1 compression??? Wonder what the power difference would be using the more popular 12-1 ratio.

[XfireZ51]

Bob,

Looks like they didn't do a bad job mimicking the LT5 power curve with the LSx motor. The first dyno looked like it was running a bit fat.

[Locobob]

Bob,

Looks like they didn't do a bad job mimicking the LT5 power curve with the LSx motor. The first dyno looked like it was running a bit fat.

I deliberately picked the motors so that they were close in peak hp and then used what I deemed to be reasonable red lines for shift points. The graphs are indeed close up until shut down time for the LS - had it continued I'd think you'd start to see it nose over big time. My basic point of this comparison is that the LT-5 lets you hang on a bit longer resulting in more power under the used curve.

[Nacho_ZR1]

I love the ZR-1 but modding it is becoming cost prohibitive. $10,000 to get mid 400 hp is insane

I agree with this 10000 percent! So much so that I decided to stop modding my ZR-1 after it comes back from Corey's with the Jeal headers, 4.30 gears, and newly tuned chip. I was going to start saving up my pennies for a 415cu but then I found this and brought it home for $7k earlier this afternoon:

http://i1139.photobucket.com/albums/n554/Nacho_ZR1/Nova_SS.jpg

http://i1139.photobucket.com/albums/n554/Nacho_ZR1/Nova_Side.jpg

It was too good of a deal to pass up. All she needs is paint! It's a 64 SS Nova with a "tiny" 406cu small block. Supposedly it's running the 1/4 mile in the 8.80's but I'll confirm that in the spring :-D

[Pete]

You boys need to remember the LS7 has 77 more cubes.

Pete

[Paul Workman]

But Paul, the LS7 doesn't drop down to our level of torque until 7K. Up to then, its always higher than the LT-5.

True, but there's where the cubes are making a difference. What I find delicious (if that's a word for engine technology) is the overall comparison of their architectural respective power/torque curves.

As for $/hp, argument, to get from a stock LT5 to a 427 LT5 it could be said that the $$ it would cost today to sell a stock ZR-1 and purchase a C6 Z06 would be pretty close, if not in favor of the LT5. (However, the $$ outlay could be substantially cheaper for the LT5 if you do most of you own work.) So, once you have arrived at displacement parity, let the mod vs mod comparisons begin!

But, that said, the C6 Z06 option also brings with it a modern performance chassis - sporting an aluminum frame and some titanium here and there too. Add to that the new fuel economy requirements and the C6 Z06 with all the trimmings (LS7) may become history and thus one day be the apple of the eye to those like us ZR-1 nuts that appreciate those "pinnacle" examples of Corvettes. So, maybe now would be the time to buy one al la the L88s of their day?

Back to the topic, Marc advertises a 415 LT5 package that makes 600+ hp. I found a dyno graph of such an engine on his web page, and compared to the LS7 architecture, the differences are striking and quite exciting especially when considering there is still a 12 ci disadvantage to the 415 motor!

http://i185.photobucket.com/albums/x220/6PPC_bucket/tech%20files/DynoC6Z06baseline-2.jpg

http://i185.photobucket.com/albums/x220/6PPC_bucket/tech%20files/Joes600hp415byHaibeckAutomotiveTech.jpg

It begs one to wonder what might have been possible were there big inch heads available for the LT5, where the practical rpm limits might have been...doanit!:fahne:

I believe this pair of graphs makes the point that Bob G is talking about when he describes the reason why it takes 25+ hp "peak" advantage over an LT5 car for the LS cars to be competitive.

All very interesting...

P.