3.4 DOHC dyno run

[pwmin]

well, heres my cobalt dyno sheets. first is uncorrected on dyno dynamics, second is uncorrected on dyno jet, and third is corrected on dyno jet. correction factor was supposedly the same on both days. same exact mods. only difference was i ran in 4th on dd and 3rd and 4th on dj. iirc, the third one is 4th gear vs. 3rd gear (4th gave better numbers). hopefully, i will get the prix to the dyno and the track next month.

[series8217]

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" ?

2.5" exhaust to a Spintech single inlet dual outlet muffler with 2.25" coming out of each side.

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

It's a stock intake manifold with the plenum and parts of the runners cut off, with a 3" aluminum tube welded on in place of all that. The throttle body is in the stock location.

Any plans to dyno new mods?

I'm probably going with forced induction so I don't think I'm going to dyno it again naturally aspirated. I just wanted to get a baseline number on the dyno I was going to use later so I can see how much I make with various boost levels.

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?

Great 1st/2nd gear spread: 3.50 1st, 2.19 2nd.
I'm using the standard FDR for the 282, the 3.61 or whatever it is.

Your engine has the same dip in torque and horsepower that mine does between 3200-4000 RPM.

Yeah they all seem to do it. Looking at my AFRs it's running very rich down there though.. so I may try to tune it out. Not taking it back to the dyno but I can feel the dip so if I can smooth it out I'll let you know.

I dont like being the @hole or anything.. but are you sure those are wheel numbers and not 'flywheel after conversion' numbers?

According to the web site from the place I went to (and others who have used that dyno), the numbers are at the wheels. Correction factors for hubs to flywheel are not known and not constant between transmissions.. so it also wouldn't really make sense if it were a corrected flywheel value. The only correction applied according to the dyno chart is "SAE". The only SAE dyno correction spec is for temperature/pressure/humidity. I will ask next time I'm there to make sure though.
Note that it is a Dynapack so the reading is ~5% higher than Dynojet readings you may be used to seeing. The shop I went to also has a Dynojet and has compared the readings between the different dynos on the same test car.
I think its safe to assume that my true whp is somewhere greater than 200. So that's still pretty good compared to stock.

because from what you are saying, you got a 50hp boost across the board from a short runner intake.

... and decked heads, lighter pistons, a balanced rotating assembly, a .030 overbore, tightly controlled bore size and ring gaps, a good exhaust system a good intake, a high flow air filter, basic tuning, no power steering pump, and a slightly lighter flywheel (Beretta flywheel).
Wasn't there a guy who dynoed 198 whp in a Fiero with a stock motor that was just balanced and blueprinted? 15-20 hp over that from the intake isn't much. My AFRs at the power peak were leaner than I expected, so it certainly has increased flow over stock..

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.

All I did was remove the stock crossover heat shield and replace it with header wrap. The manifolds and the rest of the exhaust haven't been touched..

[series8217]

Regarding the difference between Dynapack readings and Dynojet readings, this is taken from the web site of the place I took my car to :

"Let's work through a comparative example for the same car on a Dynapack and Dynojet.

Car A produces 205 hp to the hubs on the Dynapack. This would equate to between 225-230 hp at the flywheel. The same car produces 195 hp to the rollers on a Dynojet. This would equate to 222-226 hp at the flywheel. Furthermore, the difference in power matches up very well with our calculated difference due to inertial losses. And interestingly enough, we have tested just such a car on our Dynapack and a Dynojet back to back with the same results (actually 196 vs. 206 hp)."

from http://home.earthlink.net/~spchurch/...ting/id12.html


EDIT: Also, where you see "TCF" on the bottom of the dyno sheet, that is the "Transmission Correction Factor" which is normally set to account for the drivetrain loss... e.g. it would be 1.15 if flywheel power should be 15% higher than WHP. Since they have it set for 1.0 it is showing the actual measured horsepower and torque at the hubs. See dynapack's web site: http://www.dynapackusa.com/vehicle.htm

[HayesPerformance]

I wanted to know,
what is the part number on those Sealed Power hyper-eutectic pistons with coated skirts.
Are they custom made by Sealed Power?
How much did they end up costing?

I have been looking for pistons like that.

THANKS!!!!!!!!!!

Regards,
Dave

[series8217]

I wanted to know,
what is the part number on those Sealed Power hyper-eutectic pistons with coated skirts.
Are they custom made by Sealed Power?
How much did they end up costing?

I have been looking for pistons like that.

THANKS!!!!!!!!!!

Regards,
Dave

I bought them through newengineparts.com. they have them for both 91-95 motors and 96-97 (different ring sizes). They aren't custom made; they're off the shelf. Pretty cheap; like $30-$40 a piston if I remember correctly.
Part numbers
91-95 style with coated skirt: Sealed Power H813CP
96-97 style with coated skirt: Sealed Power H684CP

[z34phoenix]

hey series8217 have you tried diff lenght runners or diff volume plenums? also did you get dyno with the old IM? my interest is in changing the peak tq lower. Im contemplating trying a similar intake on my 96Z but i think i can work out a deal with a local dyno to get before and after and tune the length.

I worked out diff volume calculations and have a plan for the design... so once my car is back from the trany shop this project is going into action!

[series8217]

I haven't tried different length runners or different volume plenums. Take a look at Michael Smith's page (http://fiero.cc/fiero-tdc/members/mws/intake/index.html) for an example of extremely short runners and a huge plenum. Obviously the torque peak moves up.
Why do you want a lower torque peak? You're going to make less power.
Anyway, you'll need longer runners than stock to get a lower torque peak. Not sure how you're going to do that... but good luck and be sure to share the dyno results when you do it.
Also cam timing will move the torque peak around of course.

[z34phoenix]

from the research i have done, plenum volume also can effect peak Tq. im making the plenum in such a way to increase velocity of the incoming air. one main reason for wanting to shifting my peak lower is how weak these tranys are uptop. so if i can keep the peak power lower i wont be hurting the trany as much uptop. and it will give me more power off the line and in daily driving.