Break-in almost done by now so I up the boost to 0.8 Bar, street-tune using the LR Mafterburner and arrive at 13:1 (0-5psi), 12:1 (5-10psi) and 11:1 at 12psi, which I am happy for the meantime. Car runs great so I ask a friend out for a spin, just to compare the difference. It's a modified 88' 951 running on K27/6, MAP, 1.4Bar, guesstimate to be around 290 at the wheels.

Side by side, we floored it from rolling start, the 3.0 is very much quicker in the lower rpm and gears, particularly below 4K. By the end of 3rd gear, the 3.0 leads by 5-6 car length. 4th gear onwards, from 3K to 6K rpm, the 2.5 closes in rapidly and eventually overtook the 3.0 in a flash. Point to Note: the 3.0 revs to only 5000 as a run-in precaution

It seems the 2.5's max power is around 5500 rpm, while the 3.0 peak HP sooner.. maybe around 4500rpm but HP seems to take a dive thereafter.

Well, we are only guessing right now. Both cars will be dynoed next week.

Conclusion: $$ is better spent properly building a 2.5L so as to rev and boost higher. However, the 3L is the better car to drive in town.

 

If he's running 20psi, and you are running 12psi, I think you would have absolutley no problem turning those 5-6 car lengths into many more if you were also running 20.

 

Wait until you turn up the boost past 0.8.... no really comparison until you have both cars running at the same manifold pressure.

If you ran 1.4 bar.. I'm sure you'd blow away from the 2.5.

 

I dont you would ever run at 1.4 bar... what copression you at?

 

What boost do you plan to run? Also, what are the specs of a Kokeln Stage V?

The stroker motor is going to lower the RPM at which peak TQ occurs, but I think the bigger reasons for the power falling off could be the size of the turbine housing as well as possibly running out of your efficiency range on the compressor. I don't know if this is happening or not, since I don't know anything about kokeln turbos. At what RPM are you seeing full boost?

 

Approximate CR is 9:1 and with 1.4 Bar of boost, effective CR is 21.6!!! That's insane amount of boost. I am hoping to set it up at 0.8, 1.0 and 1.2 scramble boost for maybe 20 secs. Anyway, we'll be on the look out for knocks during the dyno next week.

 

BoostGuy, you could be right that the turbo is a mismatch. You can tell that the car is not breathing well in higher rpm, it feels like excessive back pressure to me.

I think the Kokeln Stage V is a 60-1 Hifi with a KKK housing and Stage 3 Turbine. Can someone please confirm this?

 

Why did you go for the stage 5 turbo if you are mostly runing lower boost?

 

lol thats a stage 3 SFR! lol I have a 60-1 HIFI KKK housing and stage 3 wheel. You can measure it and compare against the turbonetics book to check. Is it a 2.75 inlet?

 

Hey Songzzz here is something interesting, I have my injectors on an analyser the other night, it flow solvent through them at what ever pressure you like and measures the flow and you can see the spray pattern. Very cool. The siemens were pretty close to the cc rating, but the jet was like an arrow at most duty cycles. I dont think they are that good.

 

Can you try that with stock injectors? It'll should be interesting to see the spary pattern of the Bosch ones.

 

Yup I did! I put them next to eachother to compare. The bosch sprayed say a 90 degree angle, where the siemens were maybe 20 (max). The stock bosch units flowed 375cc. The siemens were like a rocket like one of those adjustable hoses set on the direct nozzle, while the bosch were on the spray / mist setting.

 

Hey NZ,
The inlet does not necessary mean
that it's a 60-1. A closer representation
would be the type of housing. A 2.75
inlet with an overall diameter of about
6.5 inches would mean that it's a TO4B
housing.

 

I know, but thats a measurement that may have been known, hence could discount it if it was not 2.75.

 

Before you turn up the boost on the 3.0L make sure the chips you have timing that is 3.0l friendly. Turbocharging a 3.0l requires special attention to timing!! If you are using a 2.5l chips better run high octane (race gas) in it before turning up the boost at the dyno.