GT-R turbos on the VQ37

Jayhovah · 07-21-2017, 10:59 AM

Quote:

Originally Posted by jwick

AFR shouldn't be a maybe. I'd also add a fuel pressure gauge to your list.

I don't run one... but you are probably right. I am just kind of anti-gauge. So I just did boost to make sure I don't lose a wastegate line or something and don't worry about the rest. I don't have the attention span to pay attention.

carlitos_370z · 07-21-2017, 12:30 PM

Quote:

Originally Posted by jwick

AFR shouldn't be a maybe. I'd also add a fuel pressure gauge to your list.

the AFR gauge is a most! can save you from a broken engine. Is one of the first gauge that I install on my Sti with the boost gauge

husam2012 · 07-22-2017, 07:31 PM

I will get one as soon as i can afford it! I promise guys

One thing that worried me after finally fixing that oil pressure problem is that the car smokes on deceleration. I figured something must of went wrong as the car was ran without oil pressure.. Anyways, that was running cheapo walmart 5w30 oil.

I just did a final oil change with M1 0w40 and a good quality filter along with fixing a slight kink in the oil return line and guess what! no more smoke and it doesn't stink as i drive around anymore

Now i'm just waiting for the tuner to schedule the damn dyno! He's been telling me he's busy for a week now..

husam2012 · 07-25-2017, 02:25 PM

Finally got more street tuning yesterday and did a few WOT pulls. I don't think I've ever been in a car faster than this to be honest. Only problem so far is that it's running too much boost (assuming map sensor is accurate) so my fuel injectors aren't big enough haha
It spools to 8psi by about 2800 and then keeps going to 12 psi at 4k and stops climbing there.

https://youtu.be/VsTKDqG8Nmo

Sent from my iPhone using Tapatalk

Jayhovah · 07-25-2017, 02:33 PM

Quote:

Originally Posted by husam2012

Finally got more street tuning yesterday and did a few WOT pulls. I don't think I've ever been in a car faster than this to be honest. Only problem so far is that it's running too much boost (assuming map sensor is accurate) so my fuel injectors aren't big enough haha
It spools to 8psi by about 2800 and then keeps going to 12 psi at 4k and stops climbing there.

https://youtu.be/VsTKDqG8Nmo

Sent from my iPhone using Tapatalk

those little turbos are spooling hard on you...

Some options off the top of my head, in the order preferred:

1) Get more fuel and make more power =)

2) See if you can reduce the tension on the wastegate springs

3) See if the wastegate flapper is large enough to port the wastegate out for more flow

4) Make your exhaust more restrictive - what exhaust are you running from the turbo back?

Aside from that, you can also consider the far more expensive options of plumbing in external wastegates or upgrading to much larger turbos =)

I'm sure someone smarter than me will chime in with more options as well =)

I wonder if your tuner can pull some timing to keep it from spooling so much on you? That is pure speculation as I do not really understand the technical aspects of tuning in this scenario.

Jayhovah · 07-25-2017, 02:36 PM

Also, can you tell your camera holder that landscape is superior to portrait? =)

And...clarification on #2 above. Does it spool to 8psi then slowly climb to 12psi at redline? If so, wastegate tension won't help.. as you are just out-flowing them even with the flappers wide open.

husam2012 · 07-25-2017, 02:37 PM

Quote:

Originally Posted by Jayhovah

Also, can you tell your camera holder that landscape is superior to portrait? =)

I know I tell him all the time but he never listens!

Also, it looks as if like the wastegate is opening at 12 psi and not 8. I will check what's happening tonight.

Sent from my iPhone using Tapatalk

husam2012 · 07-26-2017, 04:44 PM

So I just did a log today to 5500 rpm (GTR map sensor)

The tune is running very low timing for now just for safety. Does this look like boost creep to you guys or just a higher psi spring?

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Jayhovah · 07-26-2017, 08:00 PM

It looks pretty clear to me that your wastegates are set to ~12psi. It builds smoothly to that target and levels off.

I did some googling and it appears a stock GTR runs ~12psi... so it seems reasonable to me... though not exactly what I would have expected.

The million dollar question here is - can you change the springs on the OEM actuators, or adjust the tensioning?

husam2012 · 07-26-2017, 08:06 PM

Quote:

Originally Posted by Jayhovah

It looks pretty clear to me that your wastegates are set to ~12psi. It builds smoothly to that target and levels off.

I did some googling and it appears a stock GTR runs ~12psi... so it seems reasonable to me... though not exactly what I would have expected.

The million dollar question here is - can you change the springs on the OEM actuators, or adjust the tensioning?

Unfortunately not. I did research exactly that and everybody including my turbo said that running on just wastegate pressure (0 duty cycle in his gtr) it ran at about 8-9 psi. It's really weird that it's 12 psi on my car.

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Jayhovah · 07-26-2017, 08:13 PM

Quote:

Originally Posted by husam2012

Unfortunately not. I did research exactly that and everybody including my turbo said that running on just wastegate pressure (0 duty cycle in his gtr) it ran at about 8-9 psi. It's really weird that it's 12 psi on my car.

Sent from my iPhone using Tapatalk

Doing some more googling the answers seem a little all over the place.. though I haven't seen anyone say anything as low as 8-9... What model year did your turbos come from?

Here is the most informed-sounding (for what its worth) post:

Quote:

Boost is the same for 2012-2014 cars and then the same for 2009-2011.

It was usually measured right under 11 between (10.2-10.8psi) for the CBA then increased around 2 psi for the DBA. So yea its somewhere right at 13 stock

Max boost for 2014 GT-R? - R35 GT-R - GT-R Life

I am seeing a lot of 11, 12, 13psi posts from people. I'd be inclined to trust that kind of number since it's backed up by your own data. The curve you posted looks pretty cut and dry to me... Does not look like boost creep to me at all.

Rusty · 07-26-2017, 08:13 PM

Remember that the 3.8 and 3.7 are different motors. And the 3.7 is not a FI design. Any number of thing could cause the boost increase. Biggest I think is the difference in combustion ratios of the two. GT-R is 9 to 1, Z is 11 to 1.

Jayhovah · 07-26-2017, 08:18 PM

Quote:

Originally Posted by Rusty

Remember that the 3.8 and 3.7 are different motors. And the 3.7 is not a FI design. Any number of thing could cause the boost increase. Biggest I think is the difference in combustion ratios of the two. GT-R is 9 to 1, Z is 11 to 1.

This is true but I am not sure it applies in this case... If it was boost creep then these factors could certainly contribute. But to me this looks like his wastegates are opening at 12psi and they are activated purely on pressure alone...

Jayhovah · 07-26-2017, 08:23 PM

Here is a great post from Visconti Tuning... It differs between years and it differs between gears. (Hence why it looks like most GTR owners have no idea how much boost they make in stock form)

Stock Turbos PSI - Engine - GT-R Life

husam2012 · 07-26-2017, 08:31 PM

The thing is, that's the PSI including the oem boost solenoid which does adjust boost to a certain level.

Another interesting thing I found is this chart. Look at the standard actuator psi!

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07-25-2017, 02:25 PM	#4 (permalink)
husam2012 Track Member Join Date: Mar 2015 Location: Michigan Posts: 551 Drives: 370Z Nismo Rep Power: 9470	Finally got more street tuning yesterday and did a few WOT pulls. I don't think I've ever been in a car faster than this to be honest. Only problem so far is that it's running too much boost (assuming map sensor is accurate) so my fuel injectors aren't big enough haha It spools to 8psi by about 2800 and then keeps going to 12 psi at 4k and stops climbing there. https://youtu.be/VsTKDqG8Nmo Sent from my iPhone using Tapatalk __________________ Creator of the GTR TT Conversion Kit, NA Record Holder (401WHP) Ecutek Master Tuner (VQ37, VR30, VR38, B58, S55, S58) BTWTuning

07-26-2017, 04:44 PM	#8 (permalink)
husam2012 Track Member Join Date: Mar 2015 Location: Michigan Posts: 551 Drives: 370Z Nismo Rep Power: 9470	So I just did a log today to 5500 rpm (GTR map sensor) The tune is running very low timing for now just for safety. Does this look like boost creep to you guys or just a higher psi spring? Sent from my iPhone using Tapatalk __________________ Creator of the GTR TT Conversion Kit, NA Record Holder (401WHP) Ecutek Master Tuner (VQ37, VR30, VR38, B58, S55, S58) BTWTuning

07-26-2017, 08:13 PM	#12 (permalink)
Rusty Ronin Samurai - Assassin Join Date: Dec 2011 Location: Fayettenam,Pennsyltucky Age: 69 Posts: 35,361 Drives: 2011 Nismo GM 6M Rep Power: 2684438	Remember that the 3.8 and 3.7 are different motors. And the 3.7 is not a FI design. Any number of thing could cause the boost increase. Biggest I think is the difference in combustion ratios of the two. GT-R is 9 to 1, Z is 11 to 1. __________________ 浪人 - 殺し屋 "The Difficult Anytime, The Impossible By Appointment Only" http://www.the370z.com/members-370z-...o-journal.html

07-26-2017, 08:31 PM	#15 (permalink)
husam2012 Track Member Join Date: Mar 2015 Location: Michigan Posts: 551 Drives: 370Z Nismo Rep Power: 9470	The thing is, that's the PSI including the oem boost solenoid which does adjust boost to a certain level. Another interesting thing I found is this chart. Look at the standard actuator psi! Sent from my iPhone using Tapatalk __________________ Creator of the GTR TT Conversion Kit, NA Record Holder (401WHP) Ecutek Master Tuner (VQ37, VR30, VR38, B58, S55, S58) BTWTuning

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husam2012 Track Member Join Date: Mar 2015 Location: Michigan Posts: 551 Drives: 370Z Nismo Rep Power: 9470	I will get one as soon as i can afford it! I promise guys One thing that worried me after finally fixing that oil pressure problem is that the car smokes on deceleration. I figured something must of went wrong as the car was ran without oil pressure.. Anyways, that was running cheapo walmart 5w30 oil. I just did a final oil change with M1 0w40 and a good quality filter along with fixing a slight kink in the oil return line and guess what! no more smoke and it doesn't stink as i drive around anymore Now i'm just waiting for the tuner to schedule the damn dyno! He's been telling me he's busy for a week now..