3.2 Dyno Run today - graph

[jakermc]

Finally got my frankenstein of a car dyno'ed today. Its an '83 SC Coupe body with a '84 Carerra engine transplanted from a European cabriolet. Here are the known specs and mods to the engine:

- Euro 3.2
- No cat converter
- Heat exchangers
- 2 in 1 out custom DynaMax muffler
- Bored throttle body by MSDS, cone filter
- Intake ported and polished
- Performance chip, believed to be by Authority
- Magnecor 8.5mm wires


I'm pleased with the results as it came out right where I thought it would using Bruce Anderson's book as a guide. Not sure if 15% or 18% drivetrain loss is correct, but at 18% it puts me right at 250hp. Fairly long, flat torque curve as well.

What I can't understand is how the the guy who got 226 RWHP did it (posted a few weeks ago). I look good until I am put up against his graph.

Steve W, if you are out there - Can your chip improve upon these results? I'm open to new ideas .....

[jakermc]

One more thing worth noting, also had the car weighed. With 5/8 tank of gas it came in at 2573 lbs without the driver. With me seated the LF/RF balance is a little off so I am thinking of relocating the battery from the left to the right for an easy fix. Does this make sense? I think a stock SC is around 2750, what were the Carerras?

My set-up has Recaro SRDs, RS carpet instead of the rear seats and rear deck, RS door panels, a minimal amount of lightweight sound deadening, 7x9x16 OZ racing wheels, and a fiberglass ducktail from MA Shaw.

Here is a pic of the engine before I bought the car back in February:

[Jeff Alton]

Ummmmm, your arrow is not pointing to the throttle body.

[1987C1]

Looks like you should have a fast SC!

My Carrara (G50) was 2755 lbs stock with almost no fuel in it - a stock SC should be lighter.

Your throttle body is in the middle of the picture - just past the 90 degree bend after the air meter.

[jakermc]

Yes, I know where the throttle body is.

The previous owner took this pic and placed the arrows. In fairness, to him, he does mention the K&N filter also.

[Thomas Owen]

Big suggestion: get a Steve W chip.

[Jack Olsen]

From the sound of it, the previous owner paid for the machine work? If so, no big disappointment in the thing turning out just-better-than-stock numbers. (I've heard that even 15% is on the generous side for 915 drivetrain losses.)

The advantage to going to Steve W would be that he can tailor a chip for your particular mods, which could possibly make the intake work more effective.

Maybe more importantly, he could help with the A/F ratio. It looks like it's hovering around 14.7, which is theoretically ideal, but in practice dangerously lean -- isn't it? I'm no expert on the A/F stuff, but I'd be very conservative in combining American fuel, Euro compression and no knock sensor.

[Randy Webb]

"What I can't understand is how the the guy who got 226 RWHP did it ..."

It may well not be an accurate reading -- esp. if a wheel dyno was used. Temperature, air pressure, humidity, altitude, gas quality and etc. all affect the results are not always properly compensated for. Different engines with the exact same components will also vary somewhat. And most anyone can build a Pooschey engine to get a lot of hpo if you don't care about how long it lasts.

[jakermc]

Yes, the previous owner did all the engine mods. I paid $11K for the car back in Feb. and he threw in a pair of Recaro SRDs along with the stock leather seats, so I am am pretty happy with the charts today. Its been a fun project. The car arrived looking stock, except for the engine mods and I have been busy making turning it into a dedicated track car (your welcome, Wayne).

15% loss puts me at 241, which feels a little light for a Euro engine with these mods, though that just may be the case. The Steve W. chip could be worth a try.

I don't know much about air/fuel mixture either, other than the fact that a richer mix produces more torque. My graph shows this, just not sure if it makes sense to run that rich in the whole RPM band.

I run the car on 93 octane which should be OK with the Euro compression. My understanding is that that grade wasn't widely available in the U.S. at the time, one of the major reasons for the lower compression. 93 octane should be pretty close to what the facotry intended for Europe in 1984. But then again, I am just guessing here.

[rdane]

15% and 240 is closer I suspect. Nice torque and HP curve.

The numbers I posted from another 3.2 had a later varioram induction system bolted on and cost a pretty penny to get 220rwhp. It has since spun a rod bearing and lives no more

Normal 3.2 with "normal" mods aren't goig to spin up much more than 240 from what I have seen. Looks like you have a great set up.

[Jack Olsen]

On the same topic, let me admit to some ignorance with basic math.

The way I've been figuring drivetrain loss is less generous, i.e.:

205.1 x 1.15 = 235.9

But the other way is:

205.1 ÷ .85 = 241.3

Is the second way correct?

If so, my own dyno number of 243.2, which I used to say was a crank 279.7, jumps to a more impressive 286.1 .

(If so, I wonder if I'll see any improved lap times from my improved math? )

[rdane]

Local dyno gurus say 14/16% loss for a 915 gear box.
Someone has figured that all out before hand. I suspect it comes from original Porsche research.

That makes 243 @ the wheel 286 @ the crank. I don't know that I would call that "improved" math Jack

[D Hanson]

Numbers sound good Jack. What exhaust setup, intake and any other goodies do you have on that 3.6.

[Jack Olsen]

Just B&B headers and the chip. The engine has never been opened up.

But somebody help a math-challenged guy out -- is it divided by .85, or multiplied by 1.15?

[Ho Hum 74]

i believe it's / by .85

HPwheels = HP crank - HP crank *(0.15)
HPwheels = HP Crank*(1-0.15)=HPcrank*(0.85)
therefore HP Crank = HPwheels / 0.85

make sense?

Overall I think dyno guys inflate their numbers so that you feel good. Come on, a 3.2 making 250HP? right!

[rs911t]

Jack, the second equation is correct. If you started with the engine output, you'd multiply by 85% to correct for drivetrain loss. Division by 85% to go the other way.

[Steve W]

Jakermc, looks like you have a nice healthy engine from your dyno run. It's like a carbon copy of some U.S. Carrera's with a premuffler, sport muffler and a chip, With a polished manifold though, I would think it could have a little more at the top end. It looks similar to what Andial used to do to by hand, which measure and result the same as ExtrudeHoning the intakes. Your full throttle AFR of 14.0-14.5 is a bit too lean than it should be. Best for emissions, but not for power. So if you bring the ratio closer to between 12.6 to 13.2 (max power), you can probably get a couple of more horses. Another benefit would be that it would run cooler at full throttle and provide you an increased margin against predetonation, especially for that euro motor. It does look a little ragged past 6000. If you want to see what can be done, drop me an email.

another opinion: To compute a 15% compensation for dyno loss, take the rwhp and divide it by 0.85: fwhp= (rwhp/0.85)

[kstar]

The problem with Jack's math and the equations of everyone here is failing to account for the effects of gravity (G).

Looks like a strong engine . . . and a good deal on the car!

BR,

Kurt

[mm86911]

Jakermc - I would be that guy who dyno'd 226 rwhp with a 3.2. I think the additional mods on my engine make up the difference: mass air, B&B exhaust, port matched intake and exhaust and recent valve job. This engine is pretty tight. Here's the link to that post: Carrera 3.2 Dyno Results

[Jack Olsen]

Sweet. I'm not very bright, but now I've got an extra 6 (as in 286) crank hp.