Simple Question about Boost Level on Standard GTR R33 - GT-R Register - Official Nissan Skyline and GTR Owners Club forum

TheD · 10th September 2008, 05:40 PM

Ok This is not one of those 'How much boost is it safe to run on stock GTR Turbos?'. Questions.....

What I want to know quite simply is in second gear at 3000rpm, if you plant your foot on the gas - Immediately through to lets say 6000 rpm what is you standard boost needle in the centre console reading?

Let break it down into blocks of 500rpms...
3000 rpm - ?
3500 rpm - ?
4000 rpm - ?
and so on...

It would be really useful to have people have a look and tell me. I have been having troubles with my turbos and this will be a really useful information excersise to aid diagnostics.

Again it has to be a stock R33 GTR.

Thanks in advance.

GeorgeGTR · 10th September 2008, 05:45 PM

.7 bar But it depends on mods to if you get boost spike or drop etc.

What is your car doing?

TheD · 10th September 2008, 05:51 PM

Well it doesn't pickup in boost until around 4 or 5000! It seems its lost alot of power top end where you'd expect it to be building on spool up. Checked all the pipes, no leaks. Wired the actuator open on the forward turbo and took the car down the roadd and got absolutely no boost from the second one...

I think it is most likely damaged on the exhaust side, here is a previous link...
Help!!!!

Also the blow off valve which is standard seems to be quieter and harder to get to make noise.

SamuraiSam · 11th September 2008, 01:13 AM

If you wire open one, you won't get any boost.

TheD · 11th September 2008, 06:52 AM

Quote:

Originally Posted by SamuraiSam

If you wire open one, you won't get any boost.

In theory, if I wire the front turbo actuator open then boost should come from the rear turbo, no?

SamuraiSam · 11th September 2008, 07:03 AM

Not really. The pressures from the front turbo are nil so the rear turbo pushes 9psi of boost out of its compressor housing.. About half to 2/3 of that equalizes the mass of air differential between the front and rear compressor housing at the charge pipe merger about 1 ft beyond the compressor discharge. Then you have a whopping 3-4psi of air pressure from the merger, through pipework, across the intercooler, through pipework and the intake, throttle bodies, into the engine. How much boost is the engine really going to generate at the plenum where it's measured? Not much at all, because hardly any air is making it there.

TheD · 11th September 2008, 08:18 AM

10th September 2008, 05:40 PM	#1 (permalink)
TheD GTROC Member Join Date: Aug 2008 Location: Mostly in my pants Posts: 202	Simple Question about Boost Level on Standard GTR R33 Ok This is not one of those 'How much boost is it safe to run on stock GTR Turbos?'. Questions..... What I want to know quite simply is in second gear at 3000rpm, if you plant your foot on the gas - Immediately through to lets say 6000 rpm what is you standard boost needle in the centre console reading? Let break it down into blocks of 500rpms... 3000 rpm - ? 3500 rpm - ? 4000 rpm - ? and so on... It would be really useful to have people have a look and tell me. I have been having troubles with my turbos and this will be a really useful information excersise to aid diagnostics. Again it has to be a stock R33 GTR. Thanks in advance.

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10th September 2008, 05:45 PM	#2 (permalink)
GeorgeGTR GTR Register Member Join Date: Feb 2006 Location: York Posts: 741	.7 bar But it depends on mods to if you get boost spike or drop etc. What is your car doing?

10th September 2008, 05:51 PM	#3 (permalink)
TheD GTROC Member Join Date: Aug 2008 Location: Mostly in my pants Posts: 202	Well it doesn't pickup in boost until around 4 or 5000! It seems its lost alot of power top end where you'd expect it to be building on spool up. Checked all the pipes, no leaks. Wired the actuator open on the forward turbo and took the car down the roadd and got absolutely no boost from the second one... I think it is most likely damaged on the exhaust side, here is a previous link... Help!!!! Also the blow off valve which is standard seems to be quieter and harder to get to make noise.

11th September 2008, 01:13 AM	#4 (permalink)
SamuraiSam GTR Register Member Join Date: Oct 2007 Posts: 390	If you wire open one, you won't get any boost.

11th September 2008, 07:03 AM	#6 (permalink)
SamuraiSam GTR Register Member Join Date: Oct 2007 Posts: 390	Not really. The pressures from the front turbo are nil so the rear turbo pushes 9psi of boost out of its compressor housing.. About half to 2/3 of that equalizes the mass of air differential between the front and rear compressor housing at the charge pipe merger about 1 ft beyond the compressor discharge. Then you have a whopping 3-4psi of air pressure from the merger, through pipework, across the intercooler, through pipework and the intake, throttle bodies, into the engine. How much boost is the engine really going to generate at the plenum where it's measured? Not much at all, because hardly any air is making it there.

11th September 2008, 08:18 AM	#7 (permalink)
TheD GTROC Member Join Date: Aug 2008 Location: Mostly in my pants Posts: 202