Mike J

Well, i had a chance with the local Porsche club to put the car on the dyno today. I knew the car was running strong but its like going for a full physical...you just have this feeling they will find something!

Backing up on the dyno....


We had two to three runs to make sure the results were consistent. The runs were done from 1500 RPM to redline in 4th gear.


Here is the real-time graph...


And the final results.....


The curve is the at-the-wheel measurement without any corrections. We ran a number of other cars (911SC, 996, 944S, etc.) and the dyno appeared to be pretty accurate from what I would expect.

What I like is the flatness of the torque curve..the engine pulled great. But on each run I was mentally going through the procedure of measuring the rod bolt stretch but the engine held together fine. These cars sure are loud at redline in a closed room though!!

The car has a bone stock engine,. no chip, cat installed, and about 5000 miles since I did a total DIY rebuild. The only "tuning" I have done is to time the cams slightly differently than setting it by the factory tools.

Oh, for those who have not seen it, my DIY rebuild is documented at http://www.pcarworkshop.com/index.ph...out_the_series

Cheers,

Mike

FlatSix911

Nice work Mike - that is a strong HP number.

timothymoffat

Job well done Mike!

NP993

Can you post the numbers with SAE correction? (which is standard practice)

BTW, very cool! looks like a strong one!

MarkD

Congratulations on the confirmation! Did you really ever doubt it?

Mike J

Not being that familiar with Dyno's, I am not sure what that is. Is that the correction factor to determine crank output or?

The shop were saying that their conversion rate is about 1.38 or so... they've measured a ton of Subi's, Porsches, etc., etc., and they've all worked out to about 1.38. This shop is a Subi rally race shop...they were building two shell-up rally cars for the factory and they looked like they knew what they were doing..but that number sounds pretty high to me.

We have a list of the HP/Torque numbers for a number of Porsches...when I get my hands on that I will post them for comparison. I think relative terms is the best. I was the only 993 there but there was a 964 and a 996.

Cheers,

Mike

Mike J

Well, when the tech is pushing the engine to redline (and the rev-limiter) and the engine is screaming, I must admit to a teeny teeny bit of doubt......

Cheers,

Mike

NP993

SAE correction is just for the weather -- temperature and humidity. It usually doesn't end up making a difference of more than a few horsepower in either direction, but it is a way of ensuring a greater degree of apples-to-apples comparison. If one guy tests his car in 90-degree weather, and another tests his car on a cool summer morning, you're going to see a noticeable power difference -- cool air is denser, and makes more power. Most dyno places provide SAE-corrected numbers -- and who knows, the graph you posted might already be corrected. Your shop would know.

chris walrod

Good work Mike!

Do you have any pictures to where they tied the car down to?

Mike J

Hi Chris,

It looked like they tied down the rear from the rear jacking points. I did not look closely though but they had two tiedowns running directly to the rear of the ca, on on each sider and two more running to the sides. Being a C2, they also had the front wheels deep in the front rollers to hold it stable.

They appeared to clamp down the car lightly, run the rear wheels a bit to let the car settle into a position, and then crank it down.

Cheers,

Mike

Mike J

OK, now I understand. I will ask!

Cheers,

Mike

goldcountryboy

There is a feeling of confidence when a mechanical project comes out right. I can't even imagine the feeling of a complete engine rebuild done right. Nice job.

hpuck

Mike,
is there a reliable chip for a '96?
I would like to know what others have done.
Thanks,
Bill

Mike J

Sure but the problem is that the EPROM is soldered onto the board in the computer so its not plug and play. The common solution is to get a computer from a 97+. This process is not cheap and that additional cost has prevented me from chipping the car....so its stock.

Do a search and there is lots of info around.

Cheers,
Mike

TB993tt

Mike
I just read some of your build notes - excellent detail....

I was interested in how you found the advanced cam timing compared to before ? Did I read your notes correctly, the cams appeared to be at ~0.66 when you took the motor out and then when you rebuilt you set at 1.2 ?

Your dyno curve only goes up to ~6200rpm, I was wondering how the advanced timing has affected the top end revs ?

Many years ago I had a 964 engine rebuilt and they set the cam timing similarly advanced - it had the same effect which yours obviously has had with a nice fat torque curve but it had a definate downside in that the power tailed off very quickly over 6000rpm with revving over 6500rpm being totally pointless.

Whilst the engine was great to drive with the torque I always wondered whether I would have prefered the timing to be set so that the power was held much higher up so one could enjoy screaming to the limiter......