Turbo boost?

rnoswal · 02-26-2006, 06:12 AM

Thanks. The engine has around 40K. The turbo impeller has a few nicks in it though with just a little bit of end play. When I bought the car it had a small diameter rubber hose coming off the wastegate and on it it has an adjustable valve that is used to adjust the boost level. If I open it all the way, the pressure comes on strong but then it abrubtly kills the engine, either fuel or electric. I don't know if there is a built in pressure sensor on the stock system or not. If I screw the adjuster all the way closed it seems to have its stock pressure of around 5 psi.

Is there a pressure sensor and can it be disabled? Will it cause a code to come on with the engine light? The engine sounds and feels good and has very good oil pressure, but again stock turbo, stock piping and stock intercooler. It has an aftermarket aircleaner and the previous owner put a 3" down pipe on it and removed the cat. converter. So I guess my question now is about a psi pressure sensor. I know it has a rev limiter, but this is different.

Thanks

Russ

kwnate · 02-26-2006, 06:23 PM

You're hitting fuel cut, it's there to save your motor. Adjust your manual boost controller down until it no longer hits fuel cut. There are ways to raise this like the lexus afm with 550cc injectors or a maft pro. Factory fuel cut is between 11psi and 13psi. A little different on every car from what I've read.

rnoswal · 02-26-2006, 09:22 PM

Ok, then there is a pressure sensor. The adjuster is just a cheap piece that works but nothing more than a brass valve. So the Lexus afm and the larger injectors allow the sensor to allow for more boost? And curious about the maft pro, guess I can do a search at other aftermarket sites.

I have lowered the boost sense I did hit that cut off point so it boosts smooth again. Is that sensor hooked into the reading from the stock guage? I notice that the guage only goes to 8 psi. If some guys are getting monster boost levels, I was wondering just how they got around that cut off point.

Thanks

Russ

Isphius · 08-23-2006, 01:48 AM

For the turbo experts, How much hp could i expect from a stock 7mgte(auto trans) with rebuilt head and turbo, Brand new toyota headgasket and torqued arp head studs, Intake/exhaust/mbc, And no other mods except a mk4 intercooler nad hardpipes and as good of gas as i can get? This is all i plan to do untill i can afford an entire extra motor and rebuild. I know i can only get to 14 psi or so before boost cut, But i plan on keeping it about 11-12 just to keep everything safe and unbroken. So basically, Allt hos parts and running 11-12 psi.

kwnate · 08-23-2006, 01:52 AM

Quote:

Originally Posted by Isphius

For the turbo experts, How much hp could i expect from a stock 7mgte(auto trans) with rebuilt head and turbo, Brand new toyota headgasket and torqued arp head studs, Intake/exhaust/mbc, And no other mods except a mk4 intercooler nad hardpipes and as good of gas as i can get? This is all i plan to do untill i can afford an entire extra motor and rebuild. I know i can only get to 14 psi or so before boost cut, But i plan on keeping it about 11-12 just to keep everything safe and unbroken. So basically, Allt hos parts and running 11-12 psi.

You'll hit fuel cut around 11psi, at that point you'll probably be around 240whp.

Isphius · 08-23-2006, 03:44 AM

hmm 240 is still good enough for me. What boost can you run with the lexus afm and 550 cc injectors?

gomezmk · 08-23-2006, 04:31 AM

how much boost can be ran without needing an after market fuel regulator?

Reeves · 08-23-2006, 07:11 PM

Quote:

Originally Posted by kwnate

You'll hit fuel cut around 11psi, at that point you'll probably be around 240whp.

240 whp at 11 psi? That is only a 10 horsepower increase from stock. Whats with that?

jfunez · 08-24-2006, 02:26 AM

that doesnt sound right......

wasn,t it like 6 or 8 horses for every psi incremented?
I may be wrong but 240 @ 11 psi dont sound right to me.

02-26-2006, 06:23 PM	#2
kwnate SP58GT Join Date: Jul 2005 Location: USA Posts: 633	You're hitting fuel cut, it's there to save your motor. Adjust your manual boost controller down until it no longer hits fuel cut. There are ways to raise this like the lexus afm with 550cc injectors or a maft pro. Factory fuel cut is between 11psi and 13psi. A little different on every car from what I've read. __________________ Nate

08-23-2006, 01:48 AM	#4
Isphius 500whp yet? Join Date: Nov 2005 Location: Long branch, NJ Posts: 1,006	For the turbo experts, How much hp could i expect from a stock 7mgte(auto trans) with rebuilt head and turbo, Brand new toyota headgasket and torqued arp head studs, Intake/exhaust/mbc, And no other mods except a mk4 intercooler nad hardpipes and as good of gas as i can get? This is all i plan to do untill i can afford an entire extra motor and rebuild. I know i can only get to 14 psi or so before boost cut, But i plan on keeping it about 11-12 just to keep everything safe and unbroken. So basically, Allt hos parts and running 11-12 psi. __________________ Yay the supra assistant is gone!!! WEEE!!

08-23-2006, 03:44 AM	#6
Isphius 500whp yet? Join Date: Nov 2005 Location: Long branch, NJ Posts: 1,006	hmm 240 is still good enough for me. What boost can you run with the lexus afm and 550 cc injectors? __________________ Yay the supra assistant is gone!!! WEEE!!

08-23-2006, 04:31 AM	#7
gomezmk 3" Exhaust Join Date: Jul 2006 Location: Santa Rosa, CA Posts: 70	how much boost can be ran without needing an after market fuel regulator? Last edited by gomezmk; 08-23-2006 at 04:31 AM. Reason: miss spell

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02-26-2006, 06:12 AM	#1
rnoswal Lexus & 550's Join Date: Apr 2005 Location: Bossier City LA Posts: 556	Thanks. The engine has around 40K. The turbo impeller has a few nicks in it though with just a little bit of end play. When I bought the car it had a small diameter rubber hose coming off the wastegate and on it it has an adjustable valve that is used to adjust the boost level. If I open it all the way, the pressure comes on strong but then it abrubtly kills the engine, either fuel or electric. I don't know if there is a built in pressure sensor on the stock system or not. If I screw the adjuster all the way closed it seems to have its stock pressure of around 5 psi. Is there a pressure sensor and can it be disabled? Will it cause a code to come on with the engine light? The engine sounds and feels good and has very good oil pressure, but again stock turbo, stock piping and stock intercooler. It has an aftermarket aircleaner and the previous owner put a 3" down pipe on it and removed the cat. converter. So I guess my question now is about a psi pressure sensor. I know it has a rev limiter, but this is different. Thanks Russ

02-26-2006, 09:22 PM	#3
rnoswal Lexus & 550's Join Date: Apr 2005 Location: Bossier City LA Posts: 556	Ok, then there is a pressure sensor. The adjuster is just a cheap piece that works but nothing more than a brass valve. So the Lexus afm and the larger injectors allow the sensor to allow for more boost? And curious about the maft pro, guess I can do a search at other aftermarket sites. I have lowered the boost sense I did hit that cut off point so it boosts smooth again. Is that sensor hooked into the reading from the stock guage? I notice that the guage only goes to 8 psi. If some guys are getting monster boost levels, I was wondering just how they got around that cut off point. Thanks Russ

08-24-2006, 02:26 AM	#9
jfunez 12psi boost Join Date: Oct 2005 Location: georgia,usa Posts: 338	that doesnt sound right...... wasn,t it like 6 or 8 horses for every psi incremented? I may be wrong but 240 @ 11 psi dont sound right to me.