As i posted earlier my car arrived back from G Force today having had the work done.

The before graph is attached.
<img src="http://boards.rennlist.com/upload/Dyno.jpg" alt=" - " />

As you will see the car was putting out 274.5 HP at the wheels. The estimate is that 18% is lost through the transmition so
274.5 / 0.82 = 334 at the flywheel.

I was up slightly on factory figures of 320 mainly due to Cat Bypass. In addition conditions were very good as explained further below.

The factory figure for torque is normally 332lb ft (450Nm) at 4500RPM

Well the results of the first test were done in December and at the bottom of the graph you will see the following:

IT = Intercooler Temp = 21 degrees C
RT = Room Temp = 12 degrees C
RH = Room Humidity 53 somethings.

The Afters are as follows in next post as i want to load the graph for you.

 

The After Graph <img src="http://boards.rennlist.com/upload/DynoResultsafter1bar.jpg" alt=" - " />

The Red lines are the previous graph that was saved in December, The blue lines are the after spring fitted today.

First thing highlighted is that the Max HP at the wheels was up to 295.9 HP

This converts on the same basis 295.9 / 0.82 = 360.80 HP at the Flywheel.

G Force feel that if room conditions of the Dyno were the same as before this would also be up by about another 10HP. It was very hot in the Dyno room today and not ideal for turbo cars. You will see that the HP does not follow its natural curve almost parallaxes to first results from about 4500 revs. The reason I am told is the Intercooler temp/humidity is not as good as in normal driving conditions (Outside)
Intercooler Temp 23 degrees
Room Temp 17 degrees
Room Humidity 49 somethings

The other factors on the graph is that as you will know this is a 1bar spring fitted that settles at about 0.85 - 0.9 bar in higher revs.
The reason I get a small peak at 1.1 bar at 3500RPM is likely to be due to having Cat By pass.

Other factors are that Turbo comes in from about 200-300 RPM lower than before.

That other calculation not shown on this graph is Torque

Up approx 25% which means
415lb ft (562.50Nm) at 4500RPM

Also peak Torque is held level for a longer period from 37

 

Last line should say Peak Torque is heals from 3700 through to 4500 REVs rather than just hiiting the peak at 4500 and dropping off again at peak.

The Drive home was not great due to catching Rush Hour traffic however had a blast on the A41 before hitting the M25. Real feeling of increase in midrange power particularly in higher gears where the car just wants to Go and Go faster.

I kept having to slow down so that i could change back down to third and hear the turbo come in at about 2700RPM but each time i was back up at 110MPH plus before really getting into fourth and fear of any patrol cars i might speed past.

Came off slip roads a few times so that i could play with the 2nd gear accelaration. I was not disapointed, Car was flying.

The biggest grin was my little start in 1st after coming through the Tolls on the Dartford Crossing.
Barrier went up. so i looked either side as i crept forward and floored it. It was like Sh_t off a shoals to coin a phrase.

Red Line was almost instant I was surprised at the distance covered. Hit 2nd and just about got going before traffic would have been in the way so needed to back right off.

Cannot wait until tomorrow to go out for another play. I may even see if I can sneak out in a few minutes for a blast.

Cheers
Pierre

 

During my engine project I have found that my G50/50 which is very similar to a G50/52 has only a 15% drive loss. As far as the boost dropping below 1 bar is that potentially, the turbo can't produce enough boost in the higher gears to produce 1bar.

 

Geoffrey,
To sustain that 1 bar in higher gears, you should get the K29 which is actually a K27 with a bigger compressor housing.

 

Not sure about the Gear issue.
I know for the Dyno they tend to go for third gear results as the ratio is nearest one for one (Of what i do not know)

As you go up the Revs the Boost presure will drop slightly no matter what is my understanding. Even the factory original does it to a certain degree.
G Force do talk about a bigger Turbo being the next step to upgrade if you were going down that route. The wastegate spring is the best value Hp for you cash ratio before major costs.

G Force say that they find 18% loss correct for our porsches they get on their new rolling road. They run quite a few on there and he did find that this was about right for the 3.3 turbo which he has now done quite a few.

On your figures of a 15% loss in transmition I would have been 322 at flywheel before and 348 after but take into account the different tempreture conditions and possibly the increase is a small bit more.

Overall very happy with it for the bang per buck factor. Next I intend to do some work on suspension.

Just got back from my second little drive - No 12.30 at night but quite alot of Fog.

Cheers

 

69 COU

To confirm the above sugestion, my experance on my 91 C2T with SC cams, recored 4" I/C, euro injection, full b&b exaust and new K27-7200 is that it does run out of boost. I am luckey to get .95 bar on the dyno out of my 7200 even with boost set at over 1 bar for 340 rwhp on a low reading dyno.

I had a K27/29 hybrid and it pulled "much" harder expecialy through red line. A more efficent turbo should be good for 7-10% more power with out going over 1 bar.

Might note that the special USA Andial preped 92 C2Turbo "S2" ran a K27-7006 with C2 normal cams & a recored 4" I/C. Might be a good path to follow for resale.

Would recomend that you check you A/F ratios on your next dyno run. Could save your motor.

You are probly alright with the K27-7200 turbo with out fuel enrichment strategy as long as you set idle CO around 3%. If you get a biger turbo you will most likely need extra fuel, expecial if you want to rund sustained boost like on the track.

Happy trials!

Keith