Stock plastic upper intake manifold boost limitations?

braydo25 · 03-10-2017, 12:23 AM

Hey guys,

So long story short my Z shot a rod out of it's stock block last week. Car was running around 11psi of boost. One of the injectors started making some louder than usual noise that day. Didn't think much of it at first. First 2nd gear pull of the day I hear a lot of super loud clunking and the largest plume of white smoke out of the back of the car.. I managed to get the car towed and on my friends lift a few hours later just to find half of a rod sitting under the motor wedged into the front subframe.

Time for a built bottom end. With that, much more boost

I'm wondering though if anyone's had issues with the stock upper intake manifold dealing with boost pressure in the 15psi to 25psi range? Does the upper manifold begin to bulge, pop or split? Should I just bite the bullet and get an AAM manifold?

beemerkid · 03-10-2017, 06:18 AM

I've seen some stuff by the various 700-1k whp posters that 25psi is around where it starts to deform. No personal experience.

Jayhovah · 03-10-2017, 11:25 AM

Just curious - can you provide more details on your setup and any info you have related to what caused your failure?

hermit · 03-11-2017, 12:09 AM

Quote:

Originally Posted by Jayhovah

Just curious - can you provide more details on your setup and any info you have related to what caused your failure?

I'm not sure if he appreciates me answering for him. However, I can help supply some of this information. He has made some changes though. And, I'm unaware of the exact circumstances at the time this happened. The sale thread may be a good starting point for the information you're looking for. Though, in talking with him, he sounds like he has a plan worked out already. The link. 2013 Nismo TT 38K Miles for sale $24k

Sent from my Nexus 5X using Tapatalk

Jayhovah · 03-11-2017, 12:35 AM

Quote:

Originally Posted by hermit

I'm not sure if he appreciates me answering for him. However, I can help supply some of this information. He has made some changes though. And, I'm unaware of the exact circumstances at the time this happened. The sale thread may be a good starting point for the information you're looking for. Though, in talking with him, he sounds like he has a plan worked out already. The link. 2013 Nismo TT 38K Miles for sale $24k - Nissan 370Z Forum

Sent from my Nexus 5X using Tapatalk

Ohh I recall this car. What a deal it was... I guess I didnt read the post all the way, he mentioned he thinks an injector failed on him. Tough luck.

Glad to see it will be reborn stronger.

Rid3_FaM0uS · 03-13-2017, 01:14 PM

Quote:

Originally Posted by braydo25

Hey guys,

So long story short my Z shot a rod out of it's stock block last week. Car was running around 11psi of boost. One of the injectors started making some louder than usual noise that day. Didn't think much of it at first. First 2nd gear pull of the day I hear a lot of super loud clunking and the largest plume of white smoke out of the back of the car.. I managed to get the car towed and on my friends lift a few hours later just to find half of a rod sitting under the motor wedged into the front subframe.

Time for a built bottom end. With that, much more boost

I'm wondering though if anyone's had issues with the stock upper intake manifold dealing with boost pressure in the 15psi to 25psi range? Does the upper manifold begin to bulge, pop or split? Should I just bite the bullet and get an AAM manifold?

the injector was making noises? idk how you can hear that over the running engine. you can hardly hear an quality injector coil pulse even bench testing it in your hand. you sure it wasn't a pump failure? Aside from that, generally, rods are broken due to seized wrist pins(lack of oil pressure/viscosity).

back on topic though i daily 25psi with no issues(YET) and my high boost setting is slightly higher than thay. I will NOT however tell you this is in any way shape or form reliable of the manifold, or credible of what anyone else has done at these power levels furthermore. You must keep in mind there are only 10-15 "known" people at the most running those kinds of boost pressures on these cars, and several of which have made the RJM GT-R conversion(or some iteration of it).

Jayhovah · 03-13-2017, 01:23 PM

Has anyone considered an on-the-cheap DIY approach to stiffening up the manifold? You could grind off all the plastic reinforcement fins, then give the mani a few layers of FRP reinforcement to stengthen it up.

Spooler · 03-13-2017, 06:24 PM

If you have enough coin to get the car to a level it can produce 25psi of boost or more you no doubt don't care about going on the cheap. At that level you are spending money on reliability. Just my .02.

Jayhovah · 03-13-2017, 08:02 PM

Quote:

Originally Posted by Spooler

If you have enough coin to get the car to a level it can produce 25psi of boost or more you no doubt don't care about going on the cheap. At that level you are spending money on reliability. Just my .02.

touche.

bullitt5897 · 03-14-2017, 09:22 AM

20psi is where you start to see issues. I have seen them crack as low as 21psi. Once your over 20psi it's not of matter of if but rather when it will crack. The highest I would run a stock manifold is 25psi and even then it's playing with fire.

bullitt5897 · 03-14-2017, 10:19 AM

Quote:

Originally Posted by Jayhovah

Has anyone considered an on-the-cheap DIY approach to stiffening up the manifold? You could grind off all the plastic reinforcement fins, then give the mani a few layers of FRP reinforcement to stengthen it up.

It cracks top and bottom... this is completely unrealistic. Not to mention at the higher boost levels the thing separates at the seams...

Chuck33079 · 03-14-2017, 10:23 AM

Quote:

Originally Posted by bullitt5897

20psi is where you start to see issues. I have seen them crack as low as 21psi. Once your over 20psi it's not of matter of if but rather when it will crack. The highest I would run a stock manifold is 25psi and even then it's playing with fire.

That low, huh? I guess my definition of "low boost" is miles away from some people.

bullitt5897 · 03-14-2017, 03:35 PM

Quote:

Originally Posted by Chuck33079

That low, huh? I guess my definition of "low boost" is miles away from some people.

When your at my levels anything in the 20's is low boost hahaha

braydo25 · 03-19-2017, 02:06 PM

Quote:

Originally Posted by bullitt5897

20psi is where you start to see issues. I have seen them crack as low as 21psi. Once your over 20psi it's not of matter of if but rather when it will crack. The highest I would run a stock manifold is 25psi and even then it's playing with fire.

Ahh ok, good to know! AAM it is!

braydo25 · 03-19-2017, 02:07 PM

Quote:

Originally Posted by Rid3_FaM0uS

the injector was making noises? idk how you can hear that over the running engine. you can hardly hear an quality injector coil pulse even bench testing it in your hand. you sure it wasn't a pump failure? Aside from that, generally, rods are broken due to seized wrist pins(lack of oil pressure/viscosity).

back on topic though i daily 25psi with no issues(YET) and my high boost setting is slightly higher than thay. I will NOT however tell you this is in any way shape or form reliable of the manifold, or credible of what anyone else has done at these power levels furthermore. You must keep in mind there are only 10-15 "known" people at the most running those kinds of boost pressures on these cars, and several of which have made the RJM GT-R conversion(or some iteration of it).

I presume it was an injector. I only heard the tick on throttle. If I was in gear and downhill there was no noise at all. Basically anytime my AFR's had a reading it was ticking. When it went full lean in the event of going downhill with no throttle the tick stopped. The only think I can think that would do this is the inhectors

03-10-2017, 12:23 AM	#1 (permalink)
braydo25 Base Member Join Date: Apr 2012 Location: Tacoma Posts: 67 Drives: Nismo z34 Rep Power: 13	Stock plastic upper intake manifold boost limitations? Hey guys, So long story short my Z shot a rod out of it's stock block last week. Car was running around 11psi of boost. One of the injectors started making some louder than usual noise that day. Didn't think much of it at first. First 2nd gear pull of the day I hear a lot of super loud clunking and the largest plume of white smoke out of the back of the car.. I managed to get the car towed and on my friends lift a few hours later just to find half of a rod sitting under the motor wedged into the front subframe. Time for a built bottom end. With that, much more boost I'm wondering though if anyone's had issues with the stock upper intake manifold dealing with boost pressure in the 15psi to 25psi range? Does the upper manifold begin to bulge, pop or split? Should I just bite the bullet and get an AAM manifold? Last edited by braydo25; 03-10-2017 at 12:26 AM.

03-13-2017, 06:24 PM	#8 (permalink)
Spooler A True Z Fanatic Join Date: Jun 2014 Location: Ga Posts: 13,512 Drives: 2013 Nismo 370z Rep Power: 2684391	If you have enough coin to get the car to a level it can produce 25psi of boost or more you no doubt don't care about going on the cheap. At that level you are spending money on reliability. Just my .02. TopgunZ, hermit and wideglideleon like this.

03-14-2017, 09:22 AM	#10 (permalink)
bullitt5897 Premium Member Join Date: Jan 2009 Location: North GA Posts: 6,831 Drives: Twin Turbo Z34 Rep Power: 3682	20psi is where you start to see issues. I have seen them crack as low as 21psi. Once your over 20psi it's not of matter of if but rather when it will crack. The highest I would run a stock manifold is 25psi and even then it's playing with fire. hermit likes this. __________________ *Shop Cars: 2013 318whp Nismo VspecII 370z SOLD, 2009 1000hp+ 93oct 4.0L TT 370z Fast Intentions STAGE 4 #054*

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03-10-2017, 06:18 AM	#2 (permalink)
beemerkid Base Member Join Date: Aug 2015 Location: Santa Rosa California Posts: 67 Drives: '16 sport 6MT Rep Power: 9	I've seen some stuff by the various 700-1k whp posters that 25psi is around where it starts to deform. No personal experience.