TBI performance mods - Desktop Dyno

[Red94Chev]

All this talk of performance mods on this site, I thought I'd look at using the Desktop Dyno software (DD2000) for some of the more popular upgrades/modifications to see what kind of performance numbers I get. There are limitations of the software of course (e.g. unable to model stock vs. aftermarket manifolds, no parameter for accessory components such as A/C, fan, etc., no computer tuning, etc.), but I think it would be fun to see what kind of results I get. Head flow values were taken from magazines and #193 data was provided by Fast305.

An article reporting the utility of this software can be found at: http://www.carcraft.com/techarticles/56003/index.html Peak torque values do not seem to be modelled very well compared to dyno-derived actual values. Horsepower values seem to be closer.

Engine: 5.7L TBI engine with #193 (L05) heads, 9.3:1 compression, stock exh. manifolds, 490 cfm TB, stock cam (specs 248/252;0.382/.401 lift; 112 LSA). Stock cam specs can be found here: http://69.20.110.81/index.asp?PageAc...D&ProdID=17668

GM quotes 210 hp/300 ft-lbs of torque for these engine.

Here are the results for the stock configuration entered in DD2000: 212 hp @ 3500 RPM; 346 ft.lbs of torque @ 2500 RPM

Why such a big difference in torque? I'm not sure to be honest. I think it is a combination of things. My guess is the conservative timing settings of the stock PCM combined with a restrictive exhaust. It is known that a performance PCM can substantially improve torque from idle-2000 RPM increases torque by 25-40 ft-lbs!! Here is an example with the Vortec 5.7L engine: http://www.hypertech.com/get_dynocha...303366&tp=jpeg. This software doesn't model performance tunes and only shows the "performance potential" of an engine with a "perfect" tune. It also has one parameter for a dual plane intake and as you know, this can influence low RPM torque quite a bit. The dual plane intake modeled is considered a performance unit like the Edelbrock Performer or Performer RPM intake manifolds. Regardless of the number itself, I think the software shows the stock engine may have more torque potential than we think when properly tuned.

[Red94Chev]

Now let's have some fun!!
1st Mod: Exhaust with headers and dual exhaust

248 hp @ 4000RPM; 388 ft-lbs @ 2000 RPM

[Red94Chev]

2nd Mod: Headers/dual exhaust plus ultimate TB mods and larger TB (590 cfm)

250 hp @ 4000RPM; 389 ft-lbs at 2000 RPM

[Red94Chev]

Let's do some head changes now w/ stock cam. First up: alum. L98 head (58cc) = 9.92:1 compression ratio

274 hp @ 4500RPM; 400 ft-lbs at 2000 RPM

[Red94Chev]

Vortec heads + headers/exhaust + TB mods:

278 hp @ 4500RPM; 393 ft-lbs at 2000 RPM

[Red94Chev]

Same as above, but with Trickflow heads:

297 hp @ 4500RPM; 396 ft-lbs at 2000 RPM

[Red94Chev]

Same mods as before, but with Edelbrock centerbolt heads:

279 hp @ 4500RPM; 392 ft-lbs at 2000 RPM

[Red94Chev]

Now let's change the cam:
I've chosen the Crane Cam TruckMaster #113904 cam designed for the 87-95 truck 5.7L engine. Visit Crane Cam's website for specs

Mods: Cam plus headers/exhaust/TB mods; Stock heads

277 hp @ 4500RPM; 381 ft-lbs at 2500 RPM

[Red94Chev]

Same as above, but with alum. L98 heads

313 hp @ 5000 RPM; 396 ft-lbs at 3500 RPM

[Red94Chev]

Same as above mods, except with Vortec heads

319 hp @ 5000RPM; 387 ft-lbs at 3500 RPM

[Red94Chev]

Same as above, but with ported Vortecs (flow data taken from Chevy High Performance Mag)

336 hp @ 5000RPM; 396 ft-lbs at 3500 RPM

[Red94Chev]

Same as above, but with Trickflow heads:

340 hp @ 5000RPM; 401 ft-lbs at 3500 RPM

[Red94Chev]

Same as above but with AFR 190's (68cc = 8.93:1 compression)

341 hp @ 5000RPM; 393 ft-lbs at 3500 RPM

[justinp95]

Could you add a whipple SC with everything else stock except shorty headers, and strait pipe exhaust?

[Red94Chev]

Just for comparison, if you were to buy Edelbrock's performer package (heads, cam, exhaust, manifold) for TBI motors. Here's what you'd get:

294 hp @ 4500RPM; 397 ft-lbs at 2500 RPM

[Red94Chev]

Some observations and discussion points:

1. Exhaust mods give the biggest horsepower increases of all the mods followed by cam and head changes.

2. Alum L98 heads produce better performance than stock TBI heads

3. Vortec heads perform better than L98/TBI heads

4. Trick Flow heads outperform Vortec heads and perform as well as ported Vortecs when used with cam and headers. These heads are direct replacements for your TBI heads and do not require a Vortec-compatible intake manifold or EGR mods with the driver's side exhaust manifold/header.

5. AFR heads are arguably the best head one can buy, but their 68cc combustion chamber doesn't do it any favors. Near comparable performance compared to the Trick Flow heads. I was surprised by this, but then again, compression has a huge impact on performance. If the engine compression ratios were equal, the AFR heads would outperform the Trick Flows.

6. The Edelbrock Performer Package and Edelbrock Centerbolt heads do not perform as well as components supplied from other manufacturers.

7. Cost = Well, Vortecs are the cheapest hi-po head out there and there are many of these heads available in the bone yards. Stock Vortecs have about 320 hp potential with headers, cam, and other performance mods on a TBI-equipped engine. If you could port them yourself, then 336+ hp is possible. If you were to pay someone else to port your heads, all of a sudden, the aftermarket heads start to become a better deal. Remember to run Vortec heads, you'll have to buy Vortec/EGR-capable headers, a special Vortec TBI manifold that only GM sells right now ($$), and you may have to spring (pun intended) for new valve springs to accommodate higher lift cams greater than 0.470". Some of you guys will have an aftermarket TBI manifold and headers already on your engine. Putting Vortec heads on your TBI engine will probably cost more than you think when considering these "hidden" costs!! The dyno software shows Trick Flows were the best performing head as a bolt-on item for TBI engines and they cost just over $1000 for a pair. Prices are similar for the Edelbrock units. AFR's are much more expensive and theoretically perform better on any engine because of their awesome flow characteristics, but the lower compression generated as a bolt-on item does not make it an attractive choice considering the cost:performance ratio. If it were my money, I'd buy the Trick Flow heads!! (...and that's exactly what I did.)

8. This was pretty fun!!

[karpo]

Wow, thats some awesome data/info Red. I've been considering buying a crate motor. But after your findings, I think I'll be building my own. I realize the numbers are probably a tad inflated, but this is still some really good info.

Thanks

P.S. Which Trickflow Heads are the ones you ran?

[oldred95]

Thats pretty cool. Where did you get the softwar? And how do you change what parts you are using. Do you just punch in the manufactures specs of the heads, intake, throttle body, whatever the part may be along with the other known specs of the TBI engine and get the dyno run? I would be very intested to know what it says my engine is rated at.

[Fast305]

Originally Posted by Red94Chev

Some observations according to the software:

L98 heads produce better performance than stock TBI heads

This was pretty fun!!

Good info, but I think you are leading people to believe the L98 heads are the cast iron version that many on here speak of. You are talking about the 58cc aluminum ones though. Swapping from 193s to iron L98 heads will MAINTAIN your compression ratio at 9.3:1. The 193s and 083s both share a 64 cc chamber.

Furthermore if you take the Cast Iron head flow numbers and use them vs. the 193s, you will find that under 4,500 rpm the swirl port will do better.

There is more going on than ANY program can model. Some of these combinations would make more power, some less, thats just the fact of simulation.

Where is the lightly ported 193 (not near what I put into them, just a light cleanup, gasket match, and no major bowl work).

279HP @ 4,500 & 394 ft/lbs @ 2,000

[Fast305]

This is OldRed95's engine, I love how EVERYONE claims that a stock vortec 350 would take him. They wouldn't, it would take about 60-70 mph for a 5.3 to catch back up.

263HP @ 4,000 & 392 ft/lbs @ 2,000