ralph11sec

what could be the reason why boost won't go up at top end?

cam timing? manifold design? intake manifold?

using FR outlaw manifold, s400 fmw 1.25AR,




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new dyno results after playing with cam settings...tuning MBT...04/20/14

TheShodan

iTrader: (14)

Camshaft? Build? etc? MORE INFO, please.

ralph11sec

bseries
s2pro1s
85mm 10ish CR x 89
JG manifold
60mm wg @ 1.5bar base pressure

while tuning this today, when I boosted the care up to 32psi, power was there already.
add more DC to the solenoid, 36psi then back at 32 at top end. add more DC @ 7trpm and up, and still 32psi....

tepid1

Have you checked for a piping leak? Check all tubing to the boost control system.

May need a second solenoid to up the boost.

Are you monitoring backpressure?

dcmatt

iTrader: (7)

Did you dial in the cams? Have tried messing with cam settings?

ralph11sec

no i am not yet monitoring back pressure. i am thinking of doing that next...

i wanted to stay away from the dual solenoid setup though. i think even if i put a solenoid on the side port of the wg, it will still drop @ top end.

dcmatt,
yes. if you see the graph @ 22psi, the pressure was holding quite good. a little creeping in fact.

Airspeed

Looks like the turbo (although 94 lbs/min) is at its max flow at the current VE of your engine.
836 WHP is pretty close even with very good VE I guess + your dyno may be conservative..

tepid1

Nah. Torque is still climbing when hp starts to break off. There is still more in it.

LightningTeg

Boost leak?

Turbo-LS

iTrader: (4)

What size charge pipes are on this setup? To small would cause an issue like this. Just another thing to think about

Airspeed

Thats true. Interesting enough though: engine seems to be saying: give me more and still makes more power, but boost starts dropping.

I still think this might be a case of 'turbo says no'
There is also a S400 71mm FMW for 'those kind of people'...

Anyways, awesome power man! Over 400hp per ltr is pretty crazy still.

lsturbo33

What is your duty cycle and frequency set at for your solenoid?

tepid1

What fuel and what's timing look like up top?

Muckman

iTrader: (2)

Are you refering to the green line? I believe that is a previous run at 22psi. The OP said it was creeping at 22psi which explains the ramp up.

I don't think it's crazy this turbo is starting to peak. Youll need to ramp duty cycle with rpm to combat boost taper.

tepid1

Could be. Guess I looked at it too quickly and thought it was torque.

I would expect about 900 around 37-38psi for that turbo. Seems like either the dyno doesn't have enough load or he has a leak/choke point in his setup.

ralph11sec

Charge pipe is 3" all the way through. including using T1 a2w.
fuel and timing is approx 11.2-11.4 @ 22-24degrees.

anyway we think its turbo....ive set the solenoid to 100% at top end when the mid range is only 55% and makes 36psi....still at that numbers, its still dropping to 32 at high rpm.

lsturbo33

Double check for boost leaks. Try and lower frequency for the solenoid.

wantboost

iTrader: (2)

A quick way to see if its the turbo or solenoid is simply unhook everything from the wastegate, don't feed it a pressure reference and then do a dyno pull very slowly, see what pressure the turbo makes (obviously stop if boost goes too high or the AFRs go nuts)

Then that will tell you if you need another solenoid or if the turbo is out of breath

Muckman

iTrader: (2)

Thats a good test except back pressure could still be pushing the gate open.
In that case put the boost reference to the top wg port to keep it shut or use a giant spring.

wantboost

iTrader: (2)

That or make a block off plate and remove the wastegate all together.

At the power levels the OP is making, every little thing matters... from valve event timing, intake manifold design, runner length, etc. So there are a lot of variables that can affect performance

Maybe the motor has simply given its all at this point

tepid1

Or, put a sensor on the gate and see what it's really doing that way you know for sure.

T1 sells them.

wantboost

iTrader: (2)

That's very true, that way you can data log under varying conditions.

Oh tepid, I love the way you did your back pressure monitoring setup on your car, if you don't mind I'm going to use it for inspiration on my civic and s13 builds

ralph11sec

finally ran the car, boost still is falling at top end.

i guess its time to get a 72/74mm with a huge housing

MR.johnson

valve spring seat pressure to low?

tepid1

How the hell did you cut a 1.37 60'? Does this car have bars?