3.4 DOHC dyno run

[series8217]

221whp, 218 ft-lbs.


The graph says "flywheel torque" and "flywheel horsepower". It's just mislabeled.. It was a chassis dyno; so this is actually horsepower at the wheels. I didn't take my motor out this morning ;-P.

I have the AFRs in another chart, they were getting leaner than I wanted up top and were too rich (11:1) down low where I experienced a torque decrease after changing my intake.. so I should be able to stay safe on the top end, and gain some low end torque back, after I tune it when I have time after finals.

Video of one of the runs (didn't get a video of the peak run..) http://stsnyder.bol.ucla.edu/fiero/dyno/34dynorun2.avi

It's a 1993 3.4 DOHC in an '88 Pontiac Fiero with:

.030" overbore
Sealed Power hyper-eutectic pistons with coated skirts
ARP rod bolts
Balanced and blueprinted
Ported lower intake manifold
Short-runner upper intake with 3" pipe plenum
3" aluminum intake pipe to K&N cone in the fender well (with the TB all the way open its 3" of pipe directly to the runners )
Decked heads (.014")
Stock cam timing
Stock throttle body
BCFA chip with slightly leaner fuel curve during power enrichment (but it turns out I need more top end fueling and less around 3500)
2.5" exhaust with Spintech single-inlet dual-outlet muffler and 2.5" magnaflow cat
Getrag 282 with Quad 4 gears

Here's apic of the engine:

[Emc209i]

WOW, I cannot believe this hasn't attracted more attention. Everyone in the theads below who are asking about more power: here is a standard. Steven what size exhaust are you running anyway? 2.25" ?

[phantomgreen]

what kind of modifaction do you have going on that intake? looks sweet.

[mfewtrail]

Nice numbers. Do you have any pictures of that upper intake without the injector cover over the top of it?

[pwmin]

not too shabby. thanks for posting that. there seems to be a lack of dyno posts on here. hopefully, pretty soon, ill be getting my dyno'd.

[SappySE107]

That is better than aaron and michael from FFP with a manifold modification, slightly higher compression than stock, and a chip. That is better than not too shabby, its a clear sign to the issue we have known for a while (i cut up a plenum and posted pics of the restriction at the stock bend). Wish I had a welder to modify mine, cause I have had the tubing for a couple years as well. Im happy someone did it, cause I know for sure that I am going to do this now. Heck, perhaps we should play around with runner lengths for now and see how it goes. Cam timing would be nice to see for the powerband difference as well. Any plans to dyno new mods?

[dohcfiend]

that is VERY nice. i am liking that. what surprises me the most is the torque curve.

i hate to change the subject slightly but i want to know, how is the lq1 liking that tranny? also are you using the q4 fdr of 3.94 iirc??

lastly, you wouldn't happen to have the gear ratio's on ya would you?

[OldSkoolGP]

Your engine has the same dip in torque and horsepower that mine does between 3200-4000 RPM. That's reallly weird. I'm using a stock 96 intake setup so I still have a plenum, I can see one good thing it is doing for me is my power curves stay nice and smooth and don't sawtooth like yours does, but you have more flow and are making more power, at least over what I made on the dyno last year. It'll be interesting to get my car back on the dyno later this year and see what the new exhaust and head work has done for top end.

Sorry, enough hijacking. Nice numbers. Keep us posted!

[Identity Crisis]

I just bought a GTP w/3.4DOHC and this is making me excited.

[GPXSS]

I dont like being the @hole or anything.. but are you sure those are wheel numbers and not 'flywheel after conversion' numbers? because from what you are saying, you got a 50hp boost across the board from a short runner intake.

[z34phoenix]

he is not saying it all came from the SRI. the motor is overbored, diff pistons, ported lower intake. the matchin of the TB to the new short runner will increase intake velocity which will help low end power aswell. not to mention he has a tuned chip and custom exhaust. i think the figures are a bit higher then i would have guessed myself, but im not supriesed.

[SappySE107]

Well, closer look at the pic shows a wrapped exhaust. If those are the stock logs, you are hurting yourself with that wrap as it puts too much heat into the heads.

Im not surprised at all. The fiero has less exhaust tubing, which is going to give it quite an advantage to the W body these engines came in stock. If its on the lean side, its going to be making more than the stock tune. We know the 97 style intake adds power, as everyone making 215+ NA is using it as far as I know. This modified 93 intake is going to have the benefit of smaller runners for velocity, and removing that restriction/bend in the intake has got to do wonders for total flow and distribution. The cutouts for the spark plug wires is great for shrouding the runners on the stock intake.

Compression is going to be slightly higher with the bore and milled heads. Nothing high but more than stock.

How does opening up the TB bore to mate to the 3" tubing increase velocity? You need a LOT of flow to make up for 1/2" of material being removed. The velocity in the ports matters more to low end than feeding the plenum area.

[timg]

The other benefit is that the DynaPacks bolt to the hubs to eliminate wheel slippage and typically read higher than DynoJet, Superflow, Mustang, and Dyno Dynamics (this is usually true, though not always).

Tim

[pwmin]

everything reads higher than dyno dynamics im going to be a little shy about posting my dyno numbers since thats the type of machine im going to do all my dynoing on the prix. the dyno dynamics numbers uncorrected are about 40% lower than corrected dynojet numbers from what ive seen.

[SappySE107]

Post them up so we can have more info on how different dynos spit out the numbers.