Hi All, last week I got my '97 M6 C5 back from Tom Wong. He installed a set of Ported LS6 heads (with all new valvetrain) and a 232/234 .595/.598 Camshaft. He also installed a host of other supporting upgrades.

After his tune - my car made 400 whp and 362 wtq on his Mustang Dyno.

Since everyone on the interwebs seems to be running on a Dynojet type dyno, I wanted to throw my car on one too and see how my hand ported heads with this cam stacked up against some of the CNC ported heads.

So a week after getting it back from Tom, i threw it on Turbo Technologies Inc's Dyno here in WA, and put down 379 whp 350 tq... ( I didn't get AFR... But Tom had it dialed in Perfect on his Mustang)

I was expecting over 400... Any ideas whats going on?

How often have folks seen a Dynojet Read 5% or more lower than a Mustang dyno?

I'm gonna run out and check some things when i get home... like clogged vararam or loose plug wire (which happened to me twice now)

Any other ideas?


Dan

 

From my experience I was about 10% more on a DynoJet than a Mustang. I was stock with headers and an LS6 intake, polished TB and Corsa's and went 347rwhp 352rwtq on a DynoJet and on a Mustang saw 317rwhp and 323rwtq.
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I would think that you should have seen ~430-440rwhp on the DynoJet as compared to what you saw on the Mustang. Something must have been wrong with the setup on the DynoJet. I would think that if your off 60rwhp something must not be right.

 

So much for DJs reading higher than Mustangs, eh?
Comparing your results on 2 different dynos really isnt a legit test. Too many variables.
Also, Mustangs have operator entered correction factors, so they can read higher, or lower than DJs.
Additionally, without an A/F reading from one to another, its even harder to tell if its still running the same.
Just tuned a car, the owner had a dyno sheet from another dyno shop. Different style dyno, pretty close on the numbers, but more importantly, dead on on the A/F ratio.

 

Unfortunately I didn't get AFR from the 2nd shop, it would've made the cost $150 for just a couple baseline runs... WAY too much...

I REALLY wish i had AFR at this point... Tom had my AFR Flat at 12.5-12.7 if i remember.

The Temp was cooler on the Dynojet run, and BOTH dyno's used SAE Correction.

-Dan

 

Yeh something isn't right. 400rwhp sounds kinda high though. Any other mods?

 

Mods:
Twin Cone Intake, Bullets, CD&S Rotors, DTE LTs, DTE 4.10s, LS6 Clutch, HF-Cat/X-pipe, B&M and more.

nvm: Sounds good

 

Oh yeah - thats way out of date... LMAO

I've got vararam, and I just had Tom Wong do a Heads/Cam swap...

Ported 243s and 232/234 .595/.598 - and FULL bolt ons, except Underdrive pulley...

-Dan

 

even with long tube headers and no cats you would barely hit 385 rwhp on an ls1 .. maybe 400 if he shaved the heads to increase compression and changed your rpm limiter to 6800

too many variables that can be modified with any dyno. take it to the track and beat someone who was faster than you before

FYI Torque is the answer bro ... not HP

Who was it that said..."Horespower sells cars but Torque wins races! " ?

 

Horsepower is a function of torque - you can't have one w/o the other. They both sell, and they both win races.

Please Read my Whole Post:
I have PORTED LS6 Heads, a Torquer V2 Cam Shaft, Custom Tune, Full Exhaust, Patriot Platinum Dual Valve Springs, Blah Blah Blah - This exact Setup TYPICALLY pulls 420-440 WHP and 380-400 TQ on a Dynojet Type Dyno. And ~400hp 360tq on a Mustang Dyno.

I hit the 400hp 362tq range on the Mustang, and nobody finds it odd that i lost 20hp going to a Dynojet type Dyno?

And as far as comparing actual real life speed. I raced my friend with a Long Tubes, Intake & Tune '02 Z06 and lost from 60-130 by about 3 tenths of a second (Closed course of course...) So i'm going to race him again and see the results now after the H/C swap, I'll get that up tomorrow.

It just struck me as very strange since i'm the FIRST person i've EVER seen on the forums LOSE 20HP going from a Mustang type to a Dynojet type...

-Dan

 

Was it not written in english? Did ya not read the part about Heads Cam swap?

Hablo espanol? No?

Lea por favor mi poste entero.




-Dan

 

i would say something is not right in your setup. you didnt mention if the car was tuned. you also have to becareful with hand ported heads. i dont say this specifically about the guy who did your heads but anyone can get a drimmel and "port" some heads. granted my car is a ls6 but my heads were stock, full bolt ons and a cam. my car made 403 whp and 384 trq. my cam was a 232/232 600/600 114, very similar to yours. i am not putting the blame on your heads but something isnt right about your setup

 

For Clarity - Here's the thread I made about the recent upgrades to my car.

http://forums.corvetteforum.com/show....php?t=1790854

Mustang Dyno Chart at the Bottom.

The work was professionally done by Tom Wong, and was Dyno Tuned on his Mustang Dyno.

The result of that effort was 400 whp and 362 wtq on a Mustang Dyno. Which is a little low for this setup, compared to others w/ similar heads/cam. However i recognized that it's on a Mustang Dyno, and I wanted to put it on a Dynojet. From others i talked to, my Dynojet readin was almost assuredly going to be 20-30hp Higher than my Mustang Dyno pull at 400, giving me near 430.

The Dynojet Pulled 379. I'm going to call the owner of the shop and ask if they've calibrated their Dyno recently... Is that a valid question?

Tom is offering me a re-dyno just to see where were at, free of charge (Cause Tom Wong is awesome) and to make sure my AFR and stuff didn't get out of whack.

I'll get down there and post what we find out. In the mean time i was curious if anyone else had seen such a big drop from a Mustang dyno to a DJ.

-Dan

 

Fixed it for you.

 

Is this statement serious? I have an LS1, ported LS1 heads, custom ground cam and Kooks LT's putting 428hp/ 408tq to the rear wheels. It's fellows like you with mildly modded Z06's and even less knowledge about the capabilities of a modified LS1, that I like pulling up next to at the track. Ba bye! You either need a better mechanic or a better tuner, if you think his setup won't achieve over 400rwhp on a Dyno Jet.

You need both hp and tq to win races. You can't win without the right combination of both.

As for the gentleman with the mods putting down 400rwhp on the MD run and less on the DJ dyno. Seems like a set up issue with the DJ. The mustang dyno should read a little low, so if you forecast what was left on the table to be around 20 to 30 rwhp... you would be right at around 420 or 430. Which is where your setup should dyno on a DJ, with a tune.

Bring it to another DJ dyno and let us know what you find out.

Good luck!

 

I think some of the other posters didn't read my whole post, and just read my out of date "Mods" information (which i updated now) and thats why they thought i just had intake and exhaust...

I'm bringing it back to the original Tuner first and double checking that nothing is wrong (Since he'll do it for free) and if everything is golden there, i'm going to look into finding another dyno, as well as questioning the Company w/ the DJ (To see if theres is calibrated wrong, or what...)

I'll be sure to post up any updates.


Dan

 

So I brought it back down to Tom Wong and threw it on the dyno.

Pretty interesting results...

The AFR was flat, right where it should be up until about 5200 RPMs... then it DIVES to 9:1... pig rich... and black smoke billows out the back. Which explains the ridiculous amount of carbon crap i've had on the back of my car...

The only thing we could find that could cause the problem (after trying a couple thigns) was the air meter. Its most likely getting spikes up top, and the ECU is preparing for a massive amount of air by dumping fuel in...

I'm going to replace that and redyno it... we'll see if that fixes the issue.

Of note - the weather was nice, and my car peaked at ~396 whp with a 9:1 AFR from 5200 to 6400 RPM.... LOL With a correct AFR Tom suspects i would've hit ~415whp. hehe

So turns out the Dynojet may not have been wrong after all, and my car may indeed have a problem...

Update to come...

-Dan

 

So I went to Tom's last night and made a bunch of passes on his dyno trying to diagnose the problem.


The AFR goes Pig Rich for no apparent reason above 5k RPMs...

We tossed in a new MAF and rescaled the tune - but got the same results...

The injectors, and the Air Flow readings all appear normal. Tom doesn't see any indication or explanation for why the AFR dives to 10:1.

We pulled the Evap line, and some other fuel related vacuum line and checked for fuel... also made a pass - no difference... the car still dives pig rich...

Tom tried pulling a BUNCH of fuel - to really lean it out up top... but, surprisingly, that made it worse... went even more rich... 9:1

I reseated all the injector connections, and wiggled all the injectors, and reconnected the harness wires, and made a pass. (This after 2.5 hours of trying stuff...) and out of no where the AFR was laser flat...

So re tried it again... same result.. laser flat AFR. So we put the stock MAF back on and uploaded the original tune and reran it. Same result... everything seems fine now...

I'm not entirely sure what, if anything, we fixed. And/or what the problem was.... But for now, i guess my only option is to watch for clouds of black crap out the back again, and use that as my indicator to if i start running rich again...

Tom also suggested cleaning all the grounds... especially around my PCM...

Does anyone have any ideas where the extra fuel would be coming from, and/or what might be going on there?




Dan

 

I'm glad to hear you were able to smooth things out. Sorry to hear your not sure how you did it. Hopefully the problem is gone.

Good luck!