Paul '87 Slant

So after spending a large amount of money on mods and an engine rebuild, I had my 930 dynoed. Mods are; K27, B&B Intercooler, B&B Headers, B&B Exhaust, 964 cams, 1 bar spring. Engine had a complete rebuild at that time.

Rear wheel HP - 320

Since rear wheel is the only thing that matters, this is what I am going with. Car is in Denver at Altitude. Boost was running 13lbs. 1 bar in Denver is 13.9.

It was run on a Dynomat 5000, which is unlike any other dyno I have seen. Two machines are hooked up to the rear wheels and the vehicle is supported by them. It uses water for resistance?

Car was run in 3rd gear up to 7,000 RPM. Max HP was at 6,000, with not a big drip off up to 7. I think that the dyno was off slightly as at 6,000 in 3rd gear it was reading 101 MPH. Maybe they had the final drive ratio wrong.

What do you guys think about the output? Mis-calibrated dyno? Altitude variances? What have you guys gotten on yours?

t.p.

I think that unless a good amount of wind is blown at the engine and into the intercooler, the dyno #'s will be lower than real world conditions. While driving, you typically get nice cool air blowing around your engine and through your I/C. This will give you more power. I don't think the fans used during dyno testing are as effective.

Sameer

So after spending a large amount of money on mods and an engine rebuild, I had my 930 dynoed. Mods are; K27, B&B Intercooler, B&B Headers, B&B Exhaust, 964 cams, 1 bar spring. Engine had a complete rebuild at that time.
Rear wheel HP - 320

Paul,
I dont get it. These are the power gains I would expect.
K27, intercooler, 1 bar spring:40-50rwhp
headers, exhaust:20-30rwhp
964 cams: 15-20rwhp.

Even if you take the lower numbers, you should have a read out of 375rwhp at 1 bar. How did you only get 320bhp after spending so much.

These numbers I've quoted are rough estimates one should expect from all the tuning companies I've gathered from.

ken louie

I think the attitude in Denver can make a difference. I would check your tire pressure to make sure they are properly inflated. On your dyno run, did they check the air/fuel ratio. If you are running to lean or too rich it can really affect the output. On turbo cars I believe that 12.5:1 is the proper ratio to get the most hp. good luck

ken
79 930
86 951

Geoffrey

The dyno you put the car on is a new type of dyno and are very accurate. They use hydraulic fluid for resistance and water for cooling the unit inside. I had mine put on a Dynapack Dyno which is about the same thing and the numbers matched rwhp what the engine dyno said with the conversion. I'd also use 4th gear instead of 3rd gear on that type of dyno.

Your car came with 282fwhp stock so 320rwhp is about 368fwhp (15% multipler) which is about an 85hp gain over stock and completely in line with the mods you have done. You are probably loosing a little due to the altitude and lack of air through the IC, but all-in-all, I'd be happy.

At what RPM did you acheive full boost and how much hp is at 3000rpm?

ZCAT3

Paul - I did basically the same mods with my 86 and got 371 RWHP. The only differences I can see is that the dyno was done without the cat and my brand choices differ a bit (GHL headers, Mille Miglia exhaust, Kokeln IC, SC cams).

This is the dyno from the car in that configuration:

Paul '87 Slant

Geoffery,

I am getting full boost at 4,000, going from 2.4 at 1957 RPM to 13.0 at 4,000.

At 3,000 RPM the horsepower is approx. 120.

All in all, I am very happy with the rebuild as this car is now VERY fast. I had a little highway race with a new Viper GTS and we were dead even up to 130 and at that point, I walked away from him.

t.p.

[quote] I had a little highway race with a new Viper GTS and we were dead even up to 130 and at that point, I walked away from him. <hr></blockquote>
Isn't amazing how these old cars continue to pull at those speeds? I'm planning on going to 3.4's, and sc 330 cams soon. I already have a k27, andial I/C, and euro exhaust. Can't wait. Should I fork out for headers?

Sameer

ZCAT3,
your readout is more reliastic with those mods.

Paul,
Even if you start of at 282 which is RWHP and not FWHP, you should see ZCAT3 kind of figures with pretty much similar mods. Ask any manufacturer like PowerHaus or Andial. These are the horsepower figures you should expext with your mods and not 320rwhp.

special tool

Sameer - the figure posted by Paul of 282 is indeed flywheel horsepower for a us. model. Porsche has historically quoted only flywheel figures because of the myriad of variables. The reason that he only shows 320 is a case in point - he was lean, tire pressure, air supply etc.

ZCAT3

I think the numbers quoted by the tuners are usually quite optimistic and often involve boost levels above what you would normally want to run. I think the numbers I got on the dyno sheet above are at the upper end of what you would expect from those mods. If you use the 15% drivetrain loss figure, that puts me at 436 flywheel HP, which is pretty close to maxing out the CIS. It should also be noted that when we attached an accurate boost gauge we saw the car was getting about 1.05 max boost from the Andial 1 bar spring.

We are now running a digital boost controller with the stock .8 spring back in the car. The stock spring varies in max boost from about .78 - .85, so there is some good fluctuation there as well. One thing I would recommend for sure is that if you do all the bolt on mods and the cams, and get RWHP anywhere near what I was seeing, I would add a fuel enrichment system (we now have an Andial system in place).

KeithC2Turto

Paul,

I just had my car dynoed on a Dynomat 5000 also so I was glade to see you results which were basically the same.

My car is simmilar: C2 turbo 3.3 w SC cams,full B&B w hollow muf, & recored C2 inter cooler, EVC, & stock K27-7200 & ports.

My first run was at .9 bar boost & I got 320 rwhp also. Finaly got the boost up to .95 and I got 338 rwhp. Some variance for altitude, and tempeture.

What was interesting on my car is that I had the mixture ploted on my first 4 runs agenst torque. I have changed to "Euro"/pre 85 fuel system so I was supprized to see that it richend nicely up to 4200 rpm (hit apx 10.2 to 1 air/fuel) then it progressively leaned out in a straight line through 6300rpm (apx 13/1+).

You can see that I am running it mabie to fat to begin with. (We started at 3.0 CO but they richened it a bunch during the runs, it now hunts at idle if not warmed up)

Thus, at your power level w the smaller US injection you are likely taking a big chance.

12.5 air/fuel may be max torque on a naturaly asperated motor but it will kill our motors. Air cooled turbos should be about 11.5 or 11 to 1 under boost for cooling.

Sameer

Guys,
When Porsche measures their power ratings, it's in RWHP. 282 is in RWHP. Are you'll saying that a stock 930 turbo is producing only 282 with 15% loss in the drivetrain=239.7RWHP? Pls explain cause I'm getting really confused here.

From what I gather, 282 is RWHP.

Steve Lavigne

Paul, keep in mind that altitude will have an effect on horsepower. This will be most pronounced when off boost, especially with your engine's low compression ratio. On boost, the power loss will be much less than what a n/a car will experience. However, even if you are running the same boost level, the air will be hotter because the turbo will be working harder. Thus there will be less oxygen molecules in the air for the same pressure and ultimately less horsepower.

The dynojet dynos usually have a weather station which provides you with numbers corrected to standard atmospheric conditions. The owner/dyno operator at Carburetor Connection in Kirkland, WA told me that he has seen less than a 2 hp difference on the same car between corrected numbers from a cool Seattle day near ground level and a 100 degree day at 2,100 ft in Las Vegas using dynojet dynos at both locations.

[quote]Originally posted by Sameer:
<strong>From what I gather, 282 is RWHP.</strong><hr></blockquote>

Where do you gather this from? I have never heard a manufacturer quote rwhp. In fact, rwhp is really only for us everyday saps that don't have the development time/budget to tune with an engine dyno.

ken louie

Sameer, the figures that porsche quotes is based on flywheel horsepower not rear-wheel horsepower. As you know porsche has been conservative on their horsepower ratings.

ken
79 930
86 951