Grandprix

I had my ECU modified so I took the car to the dyno to adjust the fuel pressure. I was hoping for some gains, but every time I get the car dyno'd it has less and less power. The boost spikes around 4k RPM to 26psi, and drops to about 19 psi by 7800 RPM. It has always done that. The mechanic thinks it might be the internal wastegate. It should be running around 24psi all the time. Obviously the mechanic wants to make money and just suggested a new Garrett turbo instead of trying to fix the GT-RS.

Any ideas why the pressure would continually decline? Can that be fixed?

FYI, last year the car made 300hp, and this year with the updated ECU it made 280hp. Last year the car spiked at 28psi, and worked its way down to about 22psi.
It's not a Honda, but that shouldn't matter in this case. I like honda-tech and I thought somebody here might have an idea.

envee

whats the rest of your setup?

tony413

im gonna agree with the mechanic what is your turbo model also internal WG's arent really a smart ideal when boosting over 18psi which is probably the cause of your spiking also what boost controller are you using

Grandprix

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tony413 &raquo;</TD></TR><TR><TD CLASS="quote">im gonna agree with the mechanic what is your turbo model also internal WG's arent really a smart ideal when boosting over 18psi which is probably the cause of your spiking also what boost controller are you using </TD></TR></TABLE>

It's an HKS GT-RS. http://www.hksusa.com/products/?id=1672
The turbo the mechanic suggests (and the ECU tuner) is a Garrett GT2871R ball bearing also with an internal wastegate.

It's a Turbo XS boost controller.

tony413

so your using a MBC find a friend with a EBC and test that before you change anything else

Grandprix

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by envee &raquo;</TD></TR><TR><TD CLASS="quote">whats the rest of your setup?</TD></TR></TABLE>
Is there something specific you're looking for? Tubular exhaust manifold. Manual boost controller. Medium size intercooler. 4 silicone connectors on piping (one on each side of intercooler, one on turbo, one on intake).

tony413

MBC= manual boost controller
EBC= electronic boost controller

try my advice

envee

friend had a similar setup on his car, he was running 31 psi on internally wastegated turbo it would creep back to 22psi by redline. he welded the gate shut, got a tial and how it holds. he also went from 3in in piping to 2.75 and got a bigger intercooler. hope this helps. gl

Grandprix

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tony413 &raquo;</TD></TR><TR><TD CLASS="quote">MBC= manual boost controller
EBC= electronic boost controller

try my advice </TD></TR></TABLE>

how about just having my mechanic try a different MBC?

tony413

MBC are not good for boost after 15psi they leak, or cause boost creep, or just cant hold the pressure back for over 18psi. they were made for low boost cars as a cheap alternative if you were using a turbo xs dual or triple MBC set-up then you would be fine but one is not good enough. read my post on his page https://honda-tech.com/zerothread?id=1947892

Grandprix

Anybody else?

a1320addict

iTrader: (1)

Try porting out the flapper hole, i hate internal wastegates..lol

LeGeND4LiFe

At those boost levels, it's probably the internal wastegate, not the turbo itself. I'd try an exceptional EBC that has the ability to try to prevent boost drop off at higher rpm's, like the Turbosmart Eboost2. If that doesn't work, you probably need to go external wastegate. The 2 bolt inlet 52 trim GT2871R is identical to the HKS GT-RS. Is this on a 240?

Grandprix

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by LeGeND4LiFe &raquo;</TD></TR><TR><TD CLASS="quote">At those boost levels, it's probably the internal wastegate, not the turbo itself. I'd try an exceptional EBC that has the ability to try to prevent boost drop off at higher rpm's, like the Turbosmart Eboost2. If that doesn't work, you probably need to go external wastegate. The 2 bolt inlet 52 trim GT2871R is identical to the HKS GT-RS. Is this on a 240? </TD></TR></TABLE>

yeah, SR20

JDogg

i cant ever get a 2871 to hold boost on an sr20 either.... with either an MBC or an EBC.. they just dont seem to ever want to make over 300hp