M20b27i Turbo Dyno Results

[Climberclark]

Hi Guys,

This is my first time posting on this Forum although I've done lots of reading on here. I am looking to get some help diagnosing/understanding my latest dyno results on my m20b27i turbo project. I rebuilt the engine a little over a year ago. stock eta bottom end with flat top pistons, and stock 885 head and camshaft. I've got a tubular bottom mount manifold and an Ebay GTX3076R. currently I am getting 244whp/227wtq on 14 psi. This power number seems low to me considering how much boost I am running and compared to some other m20 turbos i've seen. The attached dyno chart shows a weird little hump just before 5,500RPM. I assumed this to be clutch slip but not 100% sure. (currently running a stock clutch)

since my last dyno session I have upgraded to wasted spark and also gone from a manual boost controller to an electric one. I'll probably upgrade the clutch next, but wanted to get some other opinions on my dyno sheet. I was shooting for at least 300whp, so needless to say I was a bit disappointed with the 244whp.

[ForcedFirebird]

You would have been close to 300 based on extrapolation, that definitely looks like clutch slippage. That turbo (if it's a real copy) would be coming in hard at 5500-ish RPM, right where you are slipping. Get a good clutch in there - the stock clutch can't even hold an s50, never-mind a turbo m20.

[Climberclark]

Some of my confusion comes from these two areas in the curve. My tuner mentioned he had a few issues with sync loss so I wasn't sure if the area in the circle 2 was due to the sync loss or the clutch slipping. I hope its clutch slipping because I have already done what I can to fix the sync loss and haven't had any issues with it driving on the street. As for the part of the curve in circle 1, I have no idea what is going on with the little dip and then upward spike. Could that just be a product of the boost spiking (due to my manual controller)? i was hoping that will be fixed with my programmable controller.

[varg]

That would be a very odd place to have a boost spike, ~5,400rpm. Boost spikes usually happen when you put your foot down and the boost starts to build, not 1,500rpm after you hit full boost.

[ForcedFirebird]

I've been wrong before, but clutch appears to start slipping around 4k RPM. Power (edit:look at TQ curve) should ramp there, even with a lazy turbo.

[the_eskimo_wonder]

I’ve got a 2.7i with a GT28 knockoff and my freshly broken in Sachs stock clutch wouldn’t even hold 8 psi. Here’s my dyno curve showing it slip. The full run is the dyno operator feathering the throttle to give me a full run. This is on a dynapack which I’ve heard is the hardest dyno for clutches. Bottom line is your car should make way more power, especially torque. Mine is at 325wtq at 14 psi and I’ve got a smaller turbo plus ignition and boost controller issues. Sent from my iPhone using Tapatalk

[Climberclark]

Do you hear anything/feel anything when the clutch slips as you are doing a pull? Any smoke or screeching sounds? I’ve got a clutch master’s fx350 on the way to eliminate any clutch slip. Hopefully that, along with wasted spark and a programable boost controller I can get over 300whp... everything else seems to be in order to make the power