1990 NA6 Kraken Turbo - Less power than expected
 

Hi everyone, first post here. I recently went turbo on my 1990 SNC NA6 with a Kraken 2560 kit. Running 6 PSI on CA 91octane fuel, I’m a bit underwhelmed by the power numbers. The torque graph isn’t zeroed properly, but the power graph is accurate. I’m a bit confused as to why I didn’t make more power. I expected roughly 150 whp.

https://cimg2.ibsrv.net/gimg/www.mia...f83974d812.png


Setup at time of dyno was:

• SpeedyEFI ECU
• Kraken top mount manifold
• GT2560R
• Kraken 3” Turboback exhaust w straight resonator and muffler
• 7” Intercooler w 2” hot side piping, 2.5” cool side piping
• Turbosmart Kompact BOV
• 700cc Bosch Injectors from Kraken
• ACT Stage 1 Clutch and Lightweight Flywheel
• 6 Speed from NB2 (pulls done in 5th gear)
• 4.3 Torsen
• AEM X-Series Wideband
• Stock internals
• Stock PCV w hot side port vented to atm
• Stock cooling system
• 6 psi wastegate actuator, no boost control
• NGK BKR7E gapped to .030”

My tune is attached.
​​​​​
My tuner, Jei at Blacktrax, mentioned issues with heat, so I think the spark map may be conservative? I am not sure though since I am new to tuning. We weren’t getting any misfiring or spark blowout. Jei suspected excessive exhaust back pressure or crank case pressure. What do you guys think my problem could be?

I recently installed:

• dual catch cans
• 323GTX PCV valve
• MAC boost solenoid
• Supermiata radiator and coolant reroute

I’m planning to go to the dyno again on 7/6 to turn up the boost. Anything else I should do to ensure max power? Thanks in advance!

https://cimg7.ibsrv.net/gimg/www.mia...bb0c2ffb0.jpeg
Maybe this sharp bend at the compressor outlet is too restrictive?

Also, I forgot to mention, compression test results were 150/140/140/150. Leakdown test results were 10/15/15/10. I was hearing leakage from the tailpipe on cylinders 2 and 3.

Looks about right. 100 x (14.7+6)/14.7 ~= 140.

If you want more you need to turn it up.

That makes sense… what about the weak top end? Does the torque taper at high RPM look normal?

Move the WG reference to the outlet of the intercooler.

Hard to say about "normal"... it does appear to be ... not great.

Consider replacing the 135* Si elbow with a 90* one - the 135* elbow looks like it's kinked.

I have been meaning to do this. I should expect WG opening later from this, right?

It was originally a 90* elbow actually. I had to cut it to turn it into a 135* because the hood would not close.

The 3-bolt compressor housing outlet and adapter make the silicone elbow sit too high. The only solution I had was to cut it. I think even with it cut, it still gets smushed by the hood a bit…

I think anybody with an NA who orders a kraken kit needs to specifically request the circular compressor outlet to avoid this issue. I didn’t know.

So you think the intake tubing is too restrictive there? I was hoping that wasn’t it because fixing it would be laborious.

Not really, but it should compensate for pressure losses caused by restrictions between the turbo and the outlet of the intercooler, like that less than optimal bend you got there.

Where's the log from the dyno pull? It's all guessing without it

Once I get my boost solenoid going, pressure loss between turbo and manifold should not matter right? The ECU will be controlling the solenoid and wastegate based on manifold pressure.

I don’t have it unfortunately. I can ask for it

I do remember though that we were getting overboost above 6k rpm, rising up to 8 psi. Torque went down despite the increased boost.

The kink in intake doesn’t help……I also wonder what the afr was.

AFR was 11.5 from 3k onward

I went out and did some pulls. Here are the logs for anyone curious

Post a screen shot of a pull from roughly 2krpm to 7krpm with MAP, RPM, spark advance, AFR, and injector pulse width. Put the cursor at ~5500rpm

This ahead of anything else. 140hp at hubs as a pressure ratio back calculation may even be considered high.

Edit - re-looked at figures. Say 136hp@ hubs = estimated c.152bhp at fly. 152/(14.5+6)*14.5 = c.108 hp fly NA equivalent. Don't know what yours would book at standard. Potentially a little low.

Motor is toast. I'm not of the opinion that throwing boost at a worn out motor is a good idea. Do a basic OEM rebuild and the power will appear.

Compression and leakdown indicates the engine is tired so it kind of makes sense that it's struggling. Also not good that the exhaust valves in cylinders 2 and 3 don't seal very well.