Andy-86IROC

Just picked up my car from the dyno shop and the results seem a little strange. I was expecting way more horsepower out of my car. It doesn't pull like it should when I drive it either. I know that because when I was trying to get the timing curve right I tapped some serious power and was very impressed. When driven like that it droned and was very loud to the point of being embarrasing so I decided to have it dyno tuned. I've attached the results.

Does anyone know what is holding my car back? Why would my torque curve slope like it does? I am positive this is in the advance curve...

Any input appreciated

My combo;

.040" over 2 bolt 350, balanced & blueprinted
Holley 750cfm VS with proform main body
Edelbrock Performer RPM Vortec, port matched to heads
Vortec heads, fully ported, scew-in studs & guide plates
Comp XE268 w/Comp 1.6 roller tips
Hooker Competition shorty headers, not super comp
Custom y-pipe using flowmaster collector
3" single to 2 chamber flowmaster dual outlet.

TH350 performance built by local shop
Pro-Torque 9.5" 3000-5500 rpm stall converter
Moser 12 bolt w 3.42 gears.

mrr23

i saw your car there. you should have seen a card in your car from me. i was talking with joe a little about it. it is the converter. too much slippage. converter not locking in. mine does the same. look at my dyno.

www.fl-thirdgen.org/mrr23-dynosheet.html

the higher the stall, ther faster the torque drops. but 357 flywheel hp ( 285 divided by .8) (20% loss) is nothing to sneeze at. also, joe figures about 20hp loss because of the converter. so about 377 flywheel hp is real good. but call joe up and talk with him more about it.

also go to www.converter.cc then go to dyno shop. it will show by dyno how different converters affect torque. you'll notice that all of them drop off after 3500rpm. and these tests were performed by www.vincihiperformance.com same place you had the car dyno'ed.

Ray87Z

Certainly seems sick. Torque peak and such should't be at so low a RPM with the XE268 cam should it? I was thinking dynos of similar Vortec motors with that cam peaked around 4000 rpm...

By my math 261rwhp is around 320 hp at the crank, should be about 30-40 higher wouldn't you think?

Hope you figure it out, coincidentally I think my Vortec setup is down on power for some reason too, I'm suspecting timing problems or weak valve springs for mine...

AlkyIROC

I agree. Too much converter. What kind of compression ratio is the engine. It sounds like the converter needs a bigger carb like an 850, more gear around 4.10 and compression ratio around 10:1

Your converter is rated to start at 3000 and 3000 is where your torque curve starts to drop off.

I need to get my car on the dyno some day for some tuning.

Andy-86IROC

Yeah, Vinci's hooked me up. 40 ft lbs and 25 hp is a good gain and the car has never driven as good, not even close. They also told me about the converter. It was recomended by Pro-Torgue when I gave them my specs. I'm still in the window for a free stall change so I'll call them tomorrow and see what they can do.
I got your card too, thanks, it was a nice surprise when I got in the car I've seen the website too, would've been nice to meet you. Those dyno charts were a great help also, maybe we can hook up some time.

I think there is much more power in there, I've felt it, I'm sure of it. The curve kit I had in there was/is a Mr. Gasket that worked well in another 350 of mine. In the new engine it seemed to work OK but never made the power. I have the weight set that came with the distributor that made awsome power but I had to have a very low base timing. It was terrible to drive and used way too much gas.

What I want to do is put THAT advance set in and go back to the dyno. If they could get it to drive as good as now I would be very happy! I'm sure we'll find more power and then they (Vinci's) can recommend the right converter.

94-6spd

I have the same engine combo as you and I curved my distributor and it felt like a different car. My base is set at 12 and 36 by 3000. I think that you will feel that power again. I set the timing and also jetted my carb. Wow! what a difference.

Andy-86IROC

Here's an engine dyno of of the same combination. Tests 3 and 4 are identical to my engine except mine is port matched on the intake side as well. They are also using a better exhaust system which is the difference between those two runs.

Vortec Engine Dyno

Andy-86IROC

I found my lost power! It wasn't in the distributer at all, it was in the math.

400 crankshaft hp minus 30% driveline loss = 280 rear wheel hp.

Simple isn't it.

That means my horsepower output is right where it should be, maybe a little more.

I guess the difference in pull that I mentioned above is because of a more sudden rush of power, not more power. I know better than to trust the butt dyno too because of this very reason.

Oh well, it's all good, I mean I DO have a 400 hp IROC :lala:

Thanks to Vinci's for the awsome work they did.:hail:

mrr23

glad to hear you figured it out. the central florida chapter of the www.fl-thirdgen.org meets the 1st saturday of each month in kissimmee. i hear your going back to vinci's. let me know when and i'll try to stop by while your there.