high boost

13bt · 01-25-2009, 01:29 AM

Hello all, im in a little predicament. I finally got to do a WOT run on my rebuilt engine and noticed the boost gauge shot up to 15psi (couldve been more not sure though) Me and a couple buddies recently changed secondary injectors prior to this. Here's a rundown of the car

JDM 13bt rebuilt with large streetport
255lph Walbro
stock primary inj., 75lb secondary inj.
aftermarket FPR
custom 3" TID with HKS filter
stock S5 JDM turbo with external wastegate mated to the exh mani.
3" turbo back exh.
removed rats nest
Greddy Type S bov

could there be a hose loose somewhere? id appreciate all the help i can get

need RX7 · 01-25-2009, 03:11 AM

It's most likely a combination of the port and the exhaust. Even bone-stock cars with open exhaust will experience a rise in boost pressure, that's why something to control the fuel with is highly recommended even with only bolt-ons.

WE3RX7 · 01-25-2009, 09:12 AM

What boost was it running before all of this? Is this the first WOT run with the new turbo/manifold/wastegate setup? I'm betting that the spring is not right in the WG. With an open exhaust, and the port you have that engine will produce a decent amount of boost. 15psi is way to much on a stock S5 turbo though - so I'd avoid WOT runs until you figure this out...

13bt · 01-25-2009, 09:54 PM

Quote:

Originally Posted by WE3RX7

What boost was it running before all of this?

well before the rebuild it was shooting the stock boost, 6psi i believe.

how would you suggest i get to the spring and check it out? would that even be possible with it still on the car?

85rx-7gsl-se · 01-25-2009, 11:06 AM

Werd, I ran a S4 Turbo with boost creeping into the 15-19psi range. Cracked a seal rather quickly.

WE3RX7 · 01-25-2009, 10:53 PM

Quote:

Originally Posted by 85rx-7gsl-se

Werd, I ran a S4 Turbo with boost creeping into the 15-19psi range. Cracked a seal rather quickly.

HA - yea, I had a stock turbo give up at 11psi!

As for the WG adjustment, you said it was an external WG, so I'd say you should be able to access the spring with the WG in the car, but I dont know your setup. External WG have springs that control when they open, and ultimately controlling what boost you can run. It sounds like you need to swap the springs out for one that suits your needs.

What WG do you have?

13bt · 01-25-2009, 11:06 PM

well the previous owner put in this setup, but it looks to be an hks style. i checked the hose that comes from the front of the turbo to a hard vacuum line then back to a thicker hose to the wastegate.

13bt · 01-28-2009, 07:34 PM

PROBLEM RESOLVED!!!!

Turns out that the line to the wastegate was pinched under the UIM so im now im boosting normally WOT

01-25-2009, 01:29 AM	#1
13bt The Newbie Join Date: Feb 2008 Location: Florida iTrader: (0) Posts: 18 Rep Power: 0	high boost Hello all, im in a little predicament. I finally got to do a WOT run on my rebuilt engine and noticed the boost gauge shot up to 15psi (couldve been more not sure though) Me and a couple buddies recently changed secondary injectors prior to this. Here's a rundown of the car JDM 13bt rebuilt with large streetport 255lph Walbro stock primary inj., 75lb secondary inj. aftermarket FPR custom 3" TID with HKS filter stock S5 JDM turbo with external wastegate mated to the exh mani. 3" turbo back exh. removed rats nest Greddy Type S bov could there be a hose loose somewhere? id appreciate all the help i can get

01-25-2009, 03:11 AM	#2
need RX7 Clean S4 Nutswinger Join Date: Mar 2008 Location: Sterling Heights, MI iTrader: (0) Posts: 485 Rep Power: 17	It's most likely a combination of the port and the exhaust. Even bone-stock cars with open exhaust will experience a rise in boost pressure, that's why something to control the fuel with is highly recommended even with only bolt-ons. __________________ -Ted -1986 Mazda RX7 Sport [DD/beater]: engine finally let go at 205k. parts car status. -1986 Mazda RX7 base [resto-mod project]: S5 n/a swap in progress.

01-25-2009, 09:12 AM	#3
WE3RX7 RCC Addict Join Date: Feb 2008 Location: VA iTrader: (1) Posts: 1,812 Rep Power: 18	What boost was it running before all of this? Is this the first WOT run with the new turbo/manifold/wastegate setup? I'm betting that the spring is not right in the WG. With an open exhaust, and the port you have that engine will produce a decent amount of boost. 15psi is way to much on a stock S5 turbo though - so I'd avoid WOT runs until you figure this out...

01-25-2009, 11:06 PM	#7
13bt The Newbie Join Date: Feb 2008 Location: Florida iTrader: (0) Posts: 18 Rep Power: 0	well the previous owner put in this setup, but it looks to be an hks style. i checked the hose that comes from the front of the turbo to a hard vacuum line then back to a thicker hose to the wastegate.

01-28-2009, 07:34 PM	#8
13bt The Newbie Join Date: Feb 2008 Location: Florida iTrader: (0) Posts: 18 Rep Power: 0	PROBLEM RESOLVED!!!! Turns out that the line to the wastegate was pinched under the UIM so im now im boosting normally WOT