A good day at the dyno...

[Top Toy]

Had a good day at the dyno with my '93. Questions frequently come up here about what various mods can do for our motors. Thought I'd post a comparison of my 2009 dyno results and today's. Mods as of '09 included siamesed plenum and injector housings, 63 mm throttle body, and B&B exhaust (stock manifolds and cats). Since then the heads have been ported, cams have been swapped, and SW headers (no cats) and mufflers have been added. Picked up 80 RWHP and 33 ft. lbs. torque. Using a 15% driveline loss, HP at the crank is now 558. Pretty amazing for a stock short block. HP/liter is almost as much as a supercharged LS9! Gotta love these motors!

[5ABI VT]

Awesome numbers ! :icon_thum. Very cool to see it picked up everywhere. How big are the cams vs stock?

[Top Toy]

Thanks! Intakes are 0.435"/238 deg. Exhausts are 0.432"/220 deg.

[XfireZ51]

Had a good day at the dyno with my '93. Questions frequently come up here about what various mods can do for our motors. Thought I'd post a comparison of my 2009 dyno results and today's. Mods as of '09 included siamesed plenum and injector housings, 63 mm throttle body, and B&B exhaust (stock manifolds and cats). Since then the heads have been ported, cams have been swapped, and SW headers (no cats) and mufflers have been added. Picked up 80 RWHP and 33 ft. lbs. torque. Using a 15% driveline loss, HP at the crank is now 558. Pretty amazing for a stock short block. HP/liter is almost as much as a supercharged LS9! Gotta love these motors!

Which is why GMs use of the LT5 moniker for a pushrod motor is sooooo frustrating. Thx Dennis.

[Hib Halverson]

Actually, your engine is making more than 558. The parsitic loss number for C4 manual powertrains which GM gave me an number of years ago was 18%. If you use that, you're making 578, but, either way that's impressive from a 350 and that's the good news.

The bad news is that, in reading the small print at the bottom of that .pdf, I noted that the data is "[ CF: Uncorrected 1.00 ]"

That means the numbers are raw data uncorrected for any atmospheric conditions present at the time the tests were run.

Any comparison between "before" and "after" power and torque numbers is not credible.

Why not go back to the dyno operator and ask him/her to provide SAE corrected data for both tests?

Lastly, looking at the AFR data at the bottom of the sheet, Dennis you need to be careful as I think you've got that engine running lean at WOT. If it was me, I'd be looking for someone to put a little more fuel to that engine...get that AFR so it's averages 12.5:1, if you're using non-blended fuel, and 12.2:1 if you're using E10 gas.

[Top Toy]

Thanks Hib!

Appreciate your comments! Yes, the numbers as shown are uncorrected. There are several different correction factors that can be applied, SAE being the most conservative. And. But I don't trust any of them to accurately adjust for changes in ambient conditions, especially when you're testing in conditions that are significantly different from Standard. The only truly valid comparisons are between tests on the same Dyno on the same day and even the same time of day. I threw out the comparison just to give those interested in similar mods an idea of what to expect. Individual results will vary, as they say, and by a lot! Re the AFR, I was shooting for an average of 12.7 which is where power and torque peaked across the rpm range. I made a few more tweaks after this last run to bring the high spots down. I have an A pillar mounted AFR gauge and keep an eye on it all the time. Have never had an issue or seen any evidence of same (I inspect the plugs and piston tops and Marc was most recently in the motor and reported no problems) running around 12.7. If you're aware of anyone that's run into problems running there, please pass it on. Timing was also optimized across most of the range (I didn't spend any time messing with it below 3000 RPM). The knock sensor kicked in a few times as I was looking for the sweet spots and was backed off accordingly.

Bottom line is the car runs great and never ceases to thrill me, even after 25 years of ownership! There's good reason why we're all so passionate about these cars!

[tiegsd]

Cool post. I dig this kind of tech stuff. Thanks!

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[tpepmeie]

Actually, your engine is making more than 558. The parsitic loss number for C4 manual powertrains which GM gave me an number of years ago was 18%. If you use that, you're making 578, but, either way that's impressive from a 350 and that's the good news.


Hib,
My personal experience doesn't back up the fixed 18% driveline loss. I believe that may have been relevant for a 300hp LT-1, with a 55 hp loss through the driveline (18%).

In my experience, a 703 BHP (STP corrected), 669 bhp (SAE 1367) engine horsepower made 638 SAE 1367 rwhp on a dynojet.

The engine dyno numbers were "green", the engine was more broken in by the time of the chassis dyno.

The chassis dyno was confirmed and consistent over three sessions and two different dynojets.

I was also surprised by the losses, given the urban legends about 15 or 18% and so on.

YMMV,
Todd

[jss06c6]

My engine was running AFR's in the 12.2 range. My understanding from Marc's writeup and my own tuning experience is this was pretty fat. Marc recommends between 12.9 and 13.1 I believe. I changed my tune to lock in at 12.9 at WOT to 7000 rpm. Coupled with a colder plug and .050 plug gap, the engine runs like a scalded dog and purrs at idle. My experience says Marc is on point. 12.9 to 13.1 AFR is a sweet spot.

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[Top Toy]

So, Todd, your results suggest that driveline loss is closer to a fixed number (approximately 50 for our cars?) rather than a percentage of FWHP. Correct? Awesome numbers, btw!

[Pete]

WOW,nice job:dancing
I just have a couple questions since you don't have corrected numbers then maybe you should dyno in the summer on a 100 degree day with 100% Humidity and tell us what the numbers are on that day.
This is why we have corrected.

Dennis,something is going on with the fuel or wideband?

Show me your 1/4 MPH i'll tell you your corrected WHP. :fahne:
Pete

[XfireZ51]

Very interesting article on parasitic losses. I don’t believe u can have a fixed loss # regardless of power. More power=more heat which = greater loss. Plus there’s a difference between steady state and one where u are constantly accelerating which is typical for chassis dyno.
Not disputing Todd’s observations, but I gotta think GM has seen enough of this stuff to make an “educated” guess.

Anyway, here’s a good read.

http://www.superstreetonline.com/how-to/engine/modp-1005-drivetrain-power-loss/

[Top Toy]

Who's got some Dyno results from bone stock cars? Comparing those numbers to the factory eating (375 or 405) should give us a better idea of our driveline losses. My first Dyno run back in the day with cat back exhaust only was 363 RWHP. Guessing 350 RWHP bone stock. That would be about a 14% loss.

[tiegsd]

Seems to me losses should be proportional to rpms. Might not be exact, but maybe good enough for govt work.

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[Wide_One]

Who's got some Dyno results from bone stock cars? Comparing those numbers to the factory eating (375 or 405) should give us a better idea of our driveline losses. My first Dyno run back in the day with cat back exhaust only was 363 RWHP. Guessing 350 RWHP bone stock. That would be about a 14% loss.


Here ya go, this is a stock California smog car with no cat backs. The time slips are not my best but consistent.

[XfireZ51]

Pete and I were noodling this a bit, and based on typical trap speeds(~112mph) for stock LT5s for 375 hp motors, we figure motor is actually more like 400chp.
Typical chassis dyno results for stock 375hp motor have been ~ 330RWHP.
That's ~17-18% loss, so GM assumption appears to work out.
Makes you want to get your hands on those original dyno sheets.

[LGAFF]

http://www.zr1.net/forum/showthread.php?t=16693&highlight=dyno+mods

[Mystic ZR-1]

....
Makes you want to get your hands on those original dyno sheets.

Perhaps a Christmas card to Betty at the NCM would help?

[XfireZ51]

Here's a very good example of a stock 91 dyno. It was of a previous member Don Yoakem. 334rwhp

[LGAFF]

Here's a very good example of a stock 91 dyno. It was of a previous member Don Yoakem. 334rwhp


That's with flowmaster exhaust and possibly a tune...

[XfireZ51]

That's with flowmaster exhaust and possibly a tune...

Maybe a cat back, but he was stock.

[Top Toy]

Here ya go, this is a stock California smog car with no cat backs. The time slips are not my best but consistent.

Wow! 387 RWHP from a stock motor is really strong! When you say "no catbacks", do you mean the exhaust was stock or disconnected?

[Top Toy]

Pete and I were noodling this a bit, and based on typical trap speeds(~112mph) for stock LT5s for 375 hp motors, we figure motor is actually more like 400chp.
Typical chassis dyno results for stock 375hp motor have been ~ 330RWHP.
That's ~17-18% loss, so GM assumption appears to work out.
Makes you want to get your hands on those original dyno sheets.
There is a Mercruiser LT5 Dyno sheet on display at the NCM. I don't recall the exact HP but noted it's for a second gen motor and was under 400 CHP. Probably more variation from engine to engine than we would expect and why they don't want to release them.

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[Wide_One]

Wow! 387 RWHP from a stock motor is really strong! When you say "no catbacks", do you mean the exhaust was stock or disconnected?
To answer the question, I meant stock exhaust Sonoma and most tracks won’t let you let you race because of noise issues. I notice on your stock or mild mod dyno slip you are at 394 that is stout as well. Different than some other the “on dyno” rev limit yours is well into the 6k+ range why would people go lower. These are amazing engines and I don’t think my engine or any other are freaks just not exploited. I agree with people who say real power is proven by track results and I go for the low hanging on that. The most fun is running heads up with equal hp cars and seeing the difference in power ban. Track proven HP is king everything else is on the bench.

[Vette73]

To answer the question, I meant stock exhaust Sonoma and most tracks won’t let you let you race because of noise issues. I notice on your stock or mild mod dyno slip you are at 394 that is stout as well. Different than some other the “on dyno” rev limit yours is well into the 6k+ range why would people go lower. These are amazing engines and I don’t think my engine or any other are freaks just not exploited. I agree with people who say real power is proven by track results and I go for the low hanging on that. The most fun is running heads up with equal hp cars and seeing the difference in power ban. Track proven HP is king everything else is on the bench.
I agree......Numbers are nice but each dyno from what I understand read differently......

From what I hear they are very good tuning agents if used properly...Power through the torque curve I'm guessing, is better than peak horsepower in the real world....

Isn't it true that mustang dynos read differently than a dyno jet?





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[tpepmeie]

There is a Mercruiser LT5 Dyno sheet on display at the NCM. I don't recall the exact HP but noted it's for a second gen motor and was under 400 CHP. Probably more variation from engine to engine than we would expect and why they don't want to release them.

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The one I have from the 93 production sign-off was 404.5hp in Test 4 trim. From memory, this is full production intake and exhaust hardware, MBT timing, and optimized fuel mixture. Equivalent to a good aftermarket calibration.

that's corrected to SAE 1349 conditions, steady state-non-accelerating.

a 500-rpm/sec acceleration test might knock that down 10 hp. So 395 SAE, for an acceleration test, engine dyno.

Chassis dyno data points I've seen for later MY LT-5s are in the 340-350 rwhp SAE corrected. A 45-55 hp "driveline loss". or 11-14% at stock power levels.

I've had a couple of these on both engine and chassis dyno, and observed closer to a fixed hp loss. But, that's just my experience and limited data points. I'll be putting another one on the engine dyno soon.

[XfireZ51]

I agree......Numbers are nice but each dyno from what I understand read differently......

From what I hear they are very good tuning agents if used properly...Power through the torque curve I'm guessing, is better than peak horsepower in the real world....

Isn't it true that mustang dynos read differently than a dyno jet?





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Two motors with the same “peak” power but the real difference is as Paul has said many times and its the area under the curve. Typically, our motors will lise powerbat a slower rate, once past peak, than an OHV or pushrod type motor.

[Top Toy]

Conventional wisdom over on the Vette forum says the Mustang dyno's register lower RWHP numbers than Dynojet by 8-12 %. Mustang dyno's use a brake to control acceleration and measure power whereas Dynojet uses an inertia drum and measures acceleration. Mustang claims their numbers are more accurate but the Dynojet numbers sure sound better!

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[jss06c6]

Have done quite a bit of research in the past couple of months regarding Dynos. Partner and I have started Crossed Flags Performance and are building a new facility in Magnolia, Tx. More on that later, but we are strongly leaning toward Hub dynos like Mainline. These allow total control over the load presented to the engine, which allows us to map the full VE tables and quickly zero in on optimal fuel and spark for any setup. Only drawback is if we want to host Dyno days, as the setup in a hub Dyno is much more involved.

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[Wide_One]

I happen to like the mustang dyno pack because it’s cleaner and less of a contraption bolts right up as the tires would from there its numerical input just my thought.
Left Side Not Right----All mine were done on the Pack gotta watch lug bolt stretch though.

[jss06c6]

I happen to like the mustang dyno pack because it’s cleaner and less of a contraption bolts right up as the tires would from there its numerical input just my thought.
Left Side Not Right----All mine were done on the Pack gotta watch lug bolt stretch though.
Thanks for the input!

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[Wide_One]

Thanks for the input!

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Welcome ......and maybe safer

[RussMcB]

Welcome ......and maybe saferWow. I'd like to know the story behind that.

It would have to be a Mustangg, wouldn't it? Sometimes I feel bad for those guys.

When DIY Tune (aka Megasquirt) tuned my car, they used the type that bolts to the rear hubs. That was the first time I had seen that in person. Pretty interesting.

[BigJohn]

There are videos on YouTube of all kinds of Dyno failures!

[efnfast]

Don't watch You Tube too much, you'll be afraid to do anything.

[Wide_One]

There are videos on YouTube of all kinds of Dyno failures!

"Tongue in cheek here"......Yeah I'm just trying to sort through all and find one that I can participate in.



Don't watch You Tube too much, you'll be afraid to do anything.


Also trying to figure how big a daredevil i want to be while I get a few hp/tq numbers.

Thought yawl pick up on mustang and the horse on horse contact!

[jss06c6]

I'm not into chasing a number. My objective with a Dyno is to tune each individual setup to obtain the best performance possible. Tuning on a hub Dyno is by far the best and safest way to tune fuel and spark. With total hydraulic control on a hub Dyno, you can set a specific rpm and it will hold that rpm from idle to WOT. Makes populating VE tables far more accurate, much faster and much safer.. changes can be made in real time and yo can see the effect immediately to torque and HP.

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[Top Toy]

Sounds like a tuner's dream!

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[Hog]

I'm not into chasing a number. My objective with a Dyno is to tune each individual setup to obtain the best performance possible. Tuning on a hub Dyno is by far the best and safest way to tune fuel and spark. With total hydraulic control on a hub Dyno, you can set a specific rpm and it will hold that rpm from idle to WOT. Makes populating VE tables far more accurate, much faster and much safer.. changes can be made in real time and yo can see the effect immediately to torque and HP.

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Realtime tuning is dependant on the software, not the dyno.


the best tuning is done in realtime, outside of a garage. A fan in front of a car doesnt come close to representing road aero influence.


If you must tune in a garage, engine dyno is the way to go, at least to get close, then unleash that beast and finish the cal under real world conditions. But as with anything, certain allowances must be made for the typical customer.

[XfireZ51]

I would agree w Paul here. Real time tuning means duplicating as much as possible the typical driving conditions the car is likely to encounter. Also, how the owner drives the car. That involves stop and go, varying traffic conditions, differing ambient temps, coolant temps, and MAT.

[jss06c6]

Gents, with all due respect, trying to replicate all MAP cells at all RPM bands on the road is very time consuming, inefficient and requires riding the brake to get cells populated. I certainly don't believe GM and Mercruiser tuned our engines by driving them around with a laptop and tuning software. (If they did, I stand corrected) I would expect they did it on an engine Dyno. The hub Dynos are effectively the same setup, but rather than bolting straight into the flywheel, they both up to the axles. So, yes, there is drivetrain loss, but you have full control of the loads and RPM presented to the engine. Having driven around for hours and hours, riding the brake trying to get decent counts in all VE table cells for my LS engines and now with my LT-5, doing it on an engine Dyno or Hub Dyno is far better and indeed safer, in my humble opinion.

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[XfireZ51]

I’m sure that GM starts out w a base map from engine dyno but why do u suppose they have laptops in cars testing on real roads and in real world driving
environs? If anyone could simulate the driving conditions on a particular road, it would be GM. No substitute for the real thing IMO.
Having said that, I would love to have access to the tools u have as well. I just don’t think u have a finished product without putting on the road.

[Top Toy]

Tuning is invariably an iterative process to get it right. Street tuning for driveability, off to the dyno for max power, then back to the street to verify the dyno tune didn't mess up drivability. In the end, some compromise is unavoidable because our 25 year old ECM's just aren't smart enough to optimize for every variation in driving conditions.

[jss06c6]

I’m sure that GM starts out w a base map from engine dyno but why do u suppose they have laptops in cars testing on real roads and in real world driving
environs? If anyone could simulate the driving conditions on a particular road, it would be GM. No substitute for the real thing IMO.
Having said that, I would love to have access to the tools u have as well. I just don’t think u have a finished product without putting on the road.
Yes, I completely agree that the fine tuning comes from real road time!

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[Hog]

I used to have a picture of 4 GM Powertrain engineers in a Chevelle out driving around finishing up the calibration for the Ramjet ZL1 454. That was the Ramjet EFI engine that was rated at 510hp@6300rpm/493 lb/ft torque, with its solid roller camshaft. That was the crate engine where the old Winters foundry tooling was used, along with some changes, were used to cast the modern aluminum BBC blocks. They only built 200 of the ZL1 Ramjets.
There were more than a couple laptops on board.


I also remember some of the ZR-1s that were wired up for testing in North America. There is a video of it around somewhere, there were many analogue gauges.


xxxxxxxx




I don't think that the OEM LT5 ECMs are lacking for any sort of conditions that it will see. The ECM makes adjustments for air temps, air pressures. Its not like if you are running a stock ECM setup that there are conditions that it cant deal with.
Of course there are advantages to other certain ECMs, but the stock ECM is fine for most users, and once you have the ability to make changes to the stock calibrations, there's really not much you cant get accomplished. The stock ECM isn't limiting top end power or anything, the rev limit can be raised(if you need to) the Injector Flow Rate is adjustable, so you can fuel whatever power level you need.


xxxxxxxxxxxxx


Operating environment is important when calibrating.
This is esp. true in the OEM supercharged cars with the GEN 4 LS9/LSA, GEN 5 LT4 and the upcoming LT5. These powertrains are influenced heavily by ambient temperatures and airflow with the amount of heat rejection equipment that is installed on them. IIRC the 2019 LT5 has 4 more "rads" in its heat rejection system.

[Pete]

I used to have a picture of 4 GM Powertrain engineers in a Chevelle out driving around finishing up the calibration for the Ramjet ZL1 454. That was the Ramjet EFI engine that was rated at 510hp@6300rpm/493 lb/ft torque, with its solid roller camshaft. That was the crate engine where the old Winters foundry tooling was used, along with some changes, were used to cast the modern aluminum BBC blocks. They only built 200 of the ZL1 Ramjets.
There were more than a couple laptops on board.


I also remember some of the ZR-1s that were wired up for testing in North America. There is a video of it around somewhere, there were many analogue gauges.


xxxxxxxx




I don't think that the OEM LT5 ECMs are lacking for any sort of conditions that it will see. The ECM makes adjustments for air temps, air pressures. Its not like if you are running a stock ECM setup that there are conditions that it cant deal with.
Of course there are advantages to other certain ECMs, but the stock ECM is fine for most users, and once you have the ability to make changes to the stock calibrations, there's really not much you cant get accomplished. The stock ECM isn't limiting top end power or anything, the rev limit can be raised(if you need to) the Injector Flow Rate is adjustable, so you can fuel whatever power level you need.


xxxxxxxxxxxxx


Operating environment is important when calibrating.
This is esp. true in the OEM supercharged cars with the GEN 4 LS9/LSA, GEN 5 LT4 and the upcoming LT5. These powertrains are influenced heavily by ambient temperatures and airflow with the amount of heat rejection equipment that is installed on them. IIRC the 2019 LT5 has 4 more "rads" in its heat rejection system.

What he said.
:cheers:

Is there better ECM/ECU technology today yes of course there is.
For our N/A LT5 our ECM is adequate to handle more power then the block can handle.

Pete

[XfireZ51]

“I don't think that the OEM LT5 ECMs are lacking for any sort of conditions that it will see. The ECM makes adjustments for air temps, air pressures. Its not like if you are running a stock ECM setup that there are conditions that it cant deal with.
Of course there are advantages to other certain ECMs, but the stock ECM is fine for most users, and once you have the ability to make changes to the stock calibrations, there's really not much you cant get accomplished. The stock ECM isn't limiting top end power or anything, the rev limit can be raised(if you need to) the Injector Flow Rate is adjustable, so you can fuel whatever power level you need.”

I am really in agreement w both Paul and Pete here. On an N/A LT-5, I don’t think the stock ECM exhibits any limitations to tuning ur setup. I wish we could bypass the ICM, but beyond that the OEM engine management is very extensive
because it needs to be.
Limited purpose motors are a different story if u want to extract the maximum.

[jss06c6]

So far, I have not seen any limitations presented by the OEM ECM. OBDII controls are a bit richer, but the ECM in the LT-5 is definitely state of the art for the time it was introduced. Managing effectively two tunes, real time, is a testament to the engineers that put this engine in the market..

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[Hog]

So far, I have not seen any limitations presented by the OEM ECM. OBDII controls are a bit richer, but the ECM in the LT-5 is definitely state of the art for the time it was introduced. Managing effectively two tunes, real time, is a testament to the engineers that put this engine in the market..

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Hear, hear!


These 2 power/torque curves certainly had different calibration requirements. Same engine, Port Throttles Open vs. Port Throttles Closed.
(dyno graph supplied by Graham Behan)


http://www.zr1.net/forum/attachment.php?attachmentid=2354&stc=1&thumb=1&d=1365253936



As you can see, she gets a bit wheezy with the Power Key Turned to Reduced/Normal from Full. Cuts down over 225 crank hp @ 6500rpm


Yes the ECMs ability to switch from 8 injectors to 16 and to keep up with the variable geometry plenum were simply amazing for 1980s technology.
Going from 16 injectors down to 8 required a TPS % zero out IIRC, at least in the OEM cals. The LT5 was a huge step coming out of the performance doldrums of the 1970s and early 80's when 3221 1980 Corvettes were available with a 180hp@4200/255lb/ft@2000rpm SAE net hp LG4 305 "gasp" with 8.5:1c/r(and a $50 rebate for such a necessity-the L48 350 made 190hp@4200rpm/280lb/ft@2400rpm with 8.2:1 c/r, the L82 made 230hp@5200rpm/ 275lb/ft torque@3600rpm with 9.0:1c/r).


So I'd agree with you and say that more than doubling the output of the engine, in less than 10 model years of a car, without using forced induction, while still maintaining emissions and still pulling a 16/25 MPG rating, is certainly an amazing engineering feat. It must have been an exciting time to be an Engineer at Lotus. or any other manufacturer.
Being able to report SAE net ratings of 375hp@6000rpm and 405hp @5800rpm and then develop the 3rd iteration of the LT5 with numbers over 525hp@7200rpm must have been a satisfying "days work".
It would take the Chev guys well over 10 years to get over 500hp into a N/A car with the 2006 LS7 and its SAE Certified 505hp@6300rpm/470 lb/ft @4700rpm, but into a car the GEN 4 LS7 went. I so wish the GEN 3 LT5 went into a C5, with the Lotus C5 powebulge hood and all.

[Vette73]

The saving grace back in the mid 70s and early 80s was the ease of modding the sbc if you couldn't afford a ZR-1...Take out the smog choked L-48 and for that matter the L-82 and put in a 383 stroker or 406 small block..

From what I understand the trannies back in the mid 70s could handle big jumps in horsepower ...If you had a four speed even better...

You can build a streetable 450 horsepower sbc for 4-5 thousand dollars......Not many people could afford to spend 60-65K on a Z back in the day...