GT-R turbos on the VQ37

phunk · 10-03-2017, 10:54 PM

Quote:

Originally Posted by Rusty

I've changed bearings before without pulling the motor. You might be able to do the same thing. Depends on how willing you are.

In the Z you need to remove the engine to remove the upper oil pan. This would get you access to the rod bearing. If you needed to do the main bearings too the bedplate will have to come off and thats essentially a full tear down except you can leave the heads on.

I suppose you could also drop the crossmember to get the upper pan off but that is a nightmare. I did that with my DE once to change the rear seal housing and it was torture being under there with the engine dripping oil on me the entire time.

Rusty · 10-03-2017, 11:04 PM

Quote:

Originally Posted by phunk

In the Z you need to remove the engine to remove the upper oil pan. This would get you access to the rod bearing. If you needed to do the main bearings too the bedplate will have to come off and thats essentially a full tear down except you can leave the heads on.

I suppose you could also drop the crossmember to get the upper pan off but that is a nightmare. I did that with my DE once to change the rear seal housing and it was torture being under there with the engine dripping oil on me the entire time.

I've lifted a couple of V8's up with hoist. Dropped the pan to change the bearings. Yeah, forgot how the bottom of the Z motor is. Not enough room, even with the motor lifted.

ihiryu · 10-04-2017, 03:18 PM

Hmm. I don't want to throw any shade around, but you had a coolant leak, and then spun a bearing. Any possibility the tune issue? Sounds like you pressurized the cooling system on the dyno ?

If you ran too much timing, or too lean, it's definitely going to pop the head gasket, pressurize the system, and leak externally. Now normally I've seen when this happens coolant comes spewing our the reservoir, but I guess it's possible to leak out of some other seal BEFORE the radiator.

And of course, you now have a spun bearing. I just find it hard to believe that a lot of other guys are boosted on stock internals, making a bit more power than you, and so far so good on their stock motors.

husam2012 · 10-04-2017, 03:21 PM

Quote:

Originally Posted by ihiryu

Hmm. I don't want to throw any shade around, but you had a coolant leak, and then spun a bearing. Any possibility the tune issue? Sounds like you pressurized the cooling system on the dyno ?

If you ran too much timing, or too lean, it's definitely going to pop the head gasket, pressurize the system, and leak externally. Now normally I've seen when this happens coolant comes spewing our the reservoir, but I guess it's possible to leak out of some other seal BEFORE the radiator.

And of course, you now have a spun bearing. I just find it hard to believe that a lot of other guys are boosted on stock internals, making a bit more power than you, and so far so good on their stock motors.

You must of missed the post where I mentioned that the car was idled with no oil pressure up to operating temp while I checked for leaks. Totally my fault that I didn't see the low oil pressure symbol on the dash.

The tuner isn't the best either but I'm almost certain it's just the oil issue and nothing else.

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adam4g63 · 10-04-2017, 03:22 PM

Wasn't the motor starved of oil, at one point?

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ihiryu · 10-04-2017, 03:42 PM

Gotcha, I did totally miss that. Like I said, I didn't want to say it to spread any type of animosity, but just another line of thinking on the possibility of what could have happen.

husam2012 · 10-04-2017, 09:56 PM

Thanks phunk for the help, but i don't really wanna mess with trying to change bearings only for it to possibly fail on me again in the future. I do have access to a lift now thankfully (at my new job) and can probably swap a used engine in over a weekend.

Now the funny thing I just discovered as I was searching for a used engine on eBay...
All of them list compression as 280-290 on all cylinders.

I did a compression test on my engine while it was warm just before the dyno and got 170-180 consistently across all 6 cylinders which I thought was normal since it was consistent.

I guess that's why the car only made 460~ whp on 93 octane.

ihiryu · 10-04-2017, 10:06 PM

I have the spec sheet, the compression psi test varies a bit. I don't recall it, but is a huge variance

SG4247 · 10-04-2017, 10:16 PM

175 psi is typical for many 11:1 engines I have tested, that are in good running order.

110-120 psi would be concerning.

rovert · 10-04-2017, 10:32 PM

From the FSM

husam2012 · 10-04-2017, 10:39 PM

So yeah, it looks like my engine was way low on compress based on the FSM.

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Jayhovah · 10-05-2017, 01:33 PM

Quote:

Originally Posted by husam2012

So yeah, it looks like my engine was way low on compress based on the FSM.

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Hope you are able to source a used motor. I've got my fingers crossed for you!

husam2012 · 10-05-2017, 02:34 PM

Quote:

Originally Posted by Jayhovah

Hope you are able to source a used motor. I've got my fingers crossed for you!

Thank you i was just looking at options since my engine still runs perfectly fine.

I thought about trading it in (putting it back to stock first) and getting a '14 nismo but i'd be losing a lot more than i would by just fixing it. If my savings looks good by december then it's time for a used engine since they are under 2k for a very low mileage motor.

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Hotrodz · 10-05-2017, 03:46 PM

Quote:

Originally Posted by husam2012

Thank you i was just looking at options since my engine still runs perfectly fine.

I thought about trading it in (putting it back to stock first) and getting a '14 nismo but i'd be losing a lot more than i would by just fixing it. If my savings looks good by december then it's time for a used engine since they are under 2k for a very low mileage motor.

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When you start looking for a motor search for a g37 motor as the price is much less than a 370z motor. I know it doesn't make since as they are the same engine however one it in a sportscar lol!

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jwick · 10-05-2017, 10:48 PM

Quote:

Originally Posted by Hotrodz

When you start looking for a motor search for a g37 motor as the price is much less than a 370z motor. I know it doesn't make since as they are the same engine however one it in a sportscar lol!

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More likely due to quantity. There are a ton more G’s out there.

10-04-2017, 03:18 PM	#408 (permalink)
ihiryu Base Member Join Date: Oct 2016 Location: TX Posts: 141 Drives: 2013 Nismo 370z 6MT Rep Power: 34	Hmm. I don't want to throw any shade around, but you had a coolant leak, and then spun a bearing. Any possibility the tune issue? Sounds like you pressurized the cooling system on the dyno ? If you ran too much timing, or too lean, it's definitely going to pop the head gasket, pressurize the system, and leak externally. Now normally I've seen when this happens coolant comes spewing our the reservoir, but I guess it's possible to leak out of some other seal BEFORE the radiator. And of course, you now have a spun bearing. I just find it hard to believe that a lot of other guys are boosted on stock internals, making a bit more power than you, and so far so good on their stock motors. husam2012 likes this.

10-04-2017, 03:42 PM	#411 (permalink)
ihiryu Base Member Join Date: Oct 2016 Location: TX Posts: 141 Drives: 2013 Nismo 370z 6MT Rep Power: 34	Gotcha, I did totally miss that. Like I said, I didn't want to say it to spread any type of animosity, but just another line of thinking on the possibility of what could have happen. adam4g63 likes this.

10-04-2017, 09:56 PM	#412 (permalink)
husam2012 Track Member Join Date: Mar 2015 Location: Michigan Posts: 549 Drives: 370Z Nismo Rep Power: 9469	Thanks phunk for the help, but i don't really wanna mess with trying to change bearings only for it to possibly fail on me again in the future. I do have access to a lift now thankfully (at my new job) and can probably swap a used engine in over a weekend. Now the funny thing I just discovered as I was searching for a used engine on eBay... All of them list compression as 280-290 on all cylinders. I did a compression test on my engine while it was warm just before the dyno and got 170-180 consistently across all 6 cylinders which I thought was normal since it was consistent. I guess that's why the car only made 460~ whp on 93 octane. Kzonts likes this.

10-04-2017, 10:16 PM	#414 (permalink)
SG4247 Track Member Join Date: Oct 2016 Location: OKC Posts: 786 Drives: 2010 touring Rep Power: 7842	175 psi is typical for many 11:1 engines I have tested, that are in good running order. 110-120 psi would be concerning. Last edited by SG4247; 10-04-2017 at 10:19 PM.

10-04-2017, 10:32 PM	#415 (permalink)
rovert Base Member Join Date: Nov 2015 Location: Australia Posts: 64 Drives: 08 Skyline 370GT Rep Power: 10	From the FSM husam2012 likes this. __________________ 08 Skyline 370GT SP Coupe 5AT: Diy TT

10-04-2017, 03:22 PM	#410 (permalink)
adam4g63 Base Member Join Date: Sep 2016 Location: Knoxville, TN Posts: 3 Drives: 2012 370z sport Rep Power: 9	Wasn't the motor starved of oil, at one point? Sent from my SAMSUNG-SM-N910A using Tapatalk

10-04-2017, 10:06 PM	#413 (permalink)
ihiryu Base Member Join Date: Oct 2016 Location: TX Posts: 141 Drives: 2013 Nismo 370z 6MT Rep Power: 34	I have the spec sheet, the compression psi test varies a bit. I don't recall it, but is a huge variance

10-04-2017, 10:39 PM	#416 (permalink)
husam2012 Track Member Join Date: Mar 2015 Location: Michigan Posts: 549 Drives: 370Z Nismo Rep Power: 9469	So yeah, it looks like my engine was way low on compress based on the FSM. 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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