get drag radials,low air pressure and a T67 turbo,gt35 is maxed bro.

 

Are we talking bout THE T67 from Forced Performance? If it is, how's the boost recovery on that? Its suppose to be slightly laggier...

 

On your tuning efforts - did your injector on time increase at all with the new turbo wheel ?

 

HI Al,

No, it didn't...to be honest with you, didn't get anymore with this new compressor wheel anyway, if anything there was a slight lost in response due to the heavier wheel... could have done just as good on a 35R...

Is boost recovery important. as in to make the peak effective powerband especially in between shifts? THe HKS cams seems to have an earlier peak torque and full boost rpm. My power band's doing it all between 6k to 9k rpm... 600 WHP all the way between that not to mention having a peak torque that is close to the peak hp as well at over 7k rpm... below 6k, there is a big chunk that's missing if you graph it over the one with the HKS 272 cam....

Hope you can help fill me in on this problem..

 

The injector time is a good indication of what is going on. When you make changes if you dont need more fuel you are not making more power.

After you do some basic tests - boost leak - compression, etc. Then its time to review some data logs and try to find the weak link in your chain which is holding you back. I would suggest also that you consider JUN cams.

What head work do you have?

 

Head is a ported with oversized 1 mm valves. I am considerring JUN cams but are they better than the HKS 272's? Problem is do you need to run like a radical cam timing with them to make power??

Boost and compression checks came out fine. Motors running fine. Will be data logging it from now on with the new Autronic SM4 ecu fairly shortly.

Thanks for your input anyway...

 

Hi Dixon, in the past when you could only make 31 psi with a big crack, that was because duty cycle on the boost control solenoid was already at 0% and even the raised shaft speed from 100% of exhaust gas powering the shaft wasn't enough to overcome the huge leak.

In the case of less severe leaks, it is entirely possible to make the same pressure levels, but at a lower boost control solenoid duty cycle, hence higher shaft speed. At the power levels and state of tune you are in, the strong likelyhood is that raising the shaft speed moves it into a more inefficient flow area. This might be the problem you are experiencing.

Logging boost control solenoid duty cycle is an option if you had baseline numbers with exactly the same turbo, but if the crack (if there is a crack) formed just after, or when you swapped the compressor wheel and you don't have a baseline, then this is not an option.

Another option is running a turbo shaft speed sensor and air temp sensors (if you're not already running some), getting the exact compressor map for your turbo and seeing how much air you should be flowing at those shaft speeds and seeing if your power levels fall within a close range of what they should be at that mass flow level. This option only shows up big problems where power is way low of what it should be. If power matches shaft speed, then you have an exhaust restriction and a pretty huge one at that if it is limiting power so absolutely. Measuring exhaust manifold pressures would be useful. The fact that your shot or nitrous is not raising power by anywhere near as much as injected mass, also points to an exhaust choke.

All this is assuming the dyno is reporting the right thing and the drivetrain is all fine. Why don't you try some acceleration timings and see if it is improving despite the dyno saying you have the same power? Not trying to put down dynos or your dyno operator - just trying to cover all the bases.. there are so many variables. You have to eliminate them one by one. A proper sensor array and data acq. helps lots.

Good luck!


Best regards
Shaun

 

BTW, I don't think there is an induction problem because nitrous is so oxygen dense that if you're injecting X shot and not getting X power, then the problems lie elsewhere. There is never problem getting that high density mass into the cylinder to burn.

Since you are reporting zero knock with low CR and race gas you may want to slowly try adding timing degree by degree. Put 1 deg back into and then run some tests over a couple days or something - whatever you're comfortable with, and if there's still no signs of knock, add another degree and repeat. This will likely help you out with the power you get out of the shot, but won't fix the problem of the power limitation you're facing. I believe the problem is elsewhere.

 

Tomei Evo, Yes Forced Performance. It`s laggy,But well worth the hit. It spools up at 3800..

 

He's still running a 2.0.

What boost level are you getting at 3,800?

 

Hey Shaun,

Thanks for the tip. The car came back from the drag strip not performing at all, and after reading the above, I will check again if we do indeed have a leak somewhere at all especially on the intake manifold or intercooler....

We've mucked around with 2 deg more timing and although we made the numbers on the dyno, it didn't show the gains on the trap...

 

What sort of power figures are we getting with this turbo?

 

power comes on at 3800hits topboost at 5500 and holds it steady to 8000rpm.at low boost i`m at 450whp@20psi on 91 octane and 650whp@28psi,we`re going to 35 psi w/ c16 within the next 2 weeks.should be dyno tuned at 700+whp.its all aem controlled 2 step n nos to help on spool up at the track.it spools very big power ,thats what i wanted.should run in the 9`s at sea level,to hot now in phoenix..110+..

 

But with a 2 litre bottom end, top boost rpm will be later than yours. WHat cams are you running? The HKS 272?? I'm assuming that the hp you're quoting is Dynojet hp right?? AM seriously considering this turbocharger even before this...was only worried bout the in between shifts with a standard gear box where it may drop below its top boost rpm and hence a slight lag factor??

 

yes 272`s ,on a dyno jet.i have mine set up for no lift shifts, so its always on boost.