Triple Blowthrough Turbo

[240Z Turbo]

FYI, VR38 downpipe studs are M8x1.25 on nut side and torque spec is 25.5ft-lbs so don't over think it.  If you're having issues sealing then it is likely due to the mating surfaces not being completely flat and that gasket, which appears to be just a flat piece of metal with no raised sealing area.  VR38 gaskets are thicker with a raised edge around the sealing surface to create the seal.  If you have future issues you might consider the remflex carbon gasket (18-005) as they conform the surface due to their ability to be compressed. 

[Dat73z]

@240zturbo in the video I posted earlier, I'm fairly certain all of the studs had stretched. I think the root cause was spiking egts when I was throwing fire out the exhaust with retarded timing when the crank pulley was walking off, but also I am running inconel shielding all around which traps the heat into the hot side. 

 

The gasket is actually a stamped SS piece with a raised lip, but it's only good for one use (attached a pic of the new gasket I have).

 

I agree simpler is better, but I also didn't want to order the same hardware to slam it together and have the same issues down the line which is why I'm now at resbond, inconel studs, and stage 8 hardware. 

 

Edit: also for reference after going through all this and doing the research, the next iteration of this build with the next turbo will be all vbands and no gaskets including the manifold. No gaskets, studs, or hardware to fail. 

Edited January 26 by Dat73z

[240Z Turbo]

That gasket looks good so you should be fine assuming the down pipe flange is flat.  You can always run it on a belt sander and you will quickly discover if the surface has high spots.  Now that you have the inconel hardware just get some good prevailing torque nuts and tighten to 25.5 ft-lbs and you're golden.  If your threads on the nut side are M8x1.25 then the prevailing torque nuts from Nissan for the GTR downpipes are an option.

 

If you're going to do a manifold from scratch then I would highly recommend that you go twinscroll as opposed to open scroll and vband.  Also, I never have issues with the 4 bolt flange leaking on any of the iterations of turbo's I've run on the EVO.  TwinScroll will give you significantly better spool and allow you to run a larger turbine, which reduces drive pressure.  The lower driver pressure makes the car way less knock prone on 93 pump allowing you to run more timing or more boost or both.  You'll want to keep the runners small using 1.25" schedule 10 pipe, which is good for applications up to about ~1100hp.  The smaller runners will keep the port velocity higher and allow for quicker response and will not affect hp vs a 1.5" schedule 10 pipe.

 

I'm a big fan of the S362 SXE (6268) and based on my testing in comparison to the Gen1 GTX3582r (6262), I lost no spool and picked up 50hp@wheels (~600whp vs ~550whp) on 93 pump.

 

 

[240Z Turbo]

My sincerest apologies as it looks like I gave you inaccurate information.  I pulled one of my old downpipe studs from a box to measure the turbine side threads and they were M10x1.5 so I struggled to understand how I thought the studs were M8.  Turns out the tap I used to measure the nut side threads was an M8x1.25 tap, but I didn't see that is was one of my heli-coil taps.  To make it worse, I was reading the Nm column instead of ft-lbs for the torque spec, but luckily that was the correct spec in ft-lbs for M8 assuming you have the highest grade stud.

 

The correct information is as follows for M10 GTR down pipe studs

Turbine side is M10x1.5 torqued to 19ft-lbs

Nut side is M10x1.25 torqued to 36ft-lbs

 

Attached is Nissan's torque table for various size bolts depending on Grade.

 

 

[Dat73z]

Thanks @240zturbo. Lots of great information, just haven't had time to process it this week. It seems the dry trq spec for m8x1.25 in your table is 21ftlbs which is what I expected. I posted the torque values I intend to use but wet with Resbond in a prior post, which are close enough to your table I think. 

 

Anyways now that it's Friday I'm starting back in on the build. Fortunately my resbond showed up so tonight I'll start back in on this turbine work. 

 

Unfortunately a supplier who was supposed to ship me an OE Nissan part sent me one of those aftermarket deals in a ziplock bag. So more parts delays again and changing of suppliers. Every time this happens, I feel like a week is lost in waiting, return shipping, etc. 

[Dat73z]

Tonight I test fit the rest of the stage 8 and modified hardware to the inconel shielding. 

 

Things don't fit as well as they used to, mostly due to the hardware on the stage 8 being larger. Since the inconel shielding is just two layers of inconel with a ceramic layer sandwiched inbetween, I'll just bend the shielding a bit to hug nicer before the final safety wiring. 

 

Debatably, Ive read online that inconel shielding and turbo blankets trap heat in allowing turbo hardware to heat higher and longer than they would exposed to free air resulting in high temp creep for the hardware. But since I drive this car on the street I'm hoping to find a compromise since I've found through this build that carbs and ethanol fuel in bowls above the turbo really benefit from the shielding. If it was a pure track machine I'd lean towards no shielding around the hardware at all for reliability since the carb radiant heat issues start coming up in stop and go traffic only. 

 

Edit: Just to document this and perhaps only those that have run these setups know (which is the point of documenting this build thread since I've never seen this info out there...) but one thing I've found is when you're boosting, the atomization of the fuel and charge air cause the carbs to get ice cold to the touch. So even when you've parked and heat soaked to where the carbs have boiled over/fuel had completely evaporated and you will literally burn skin touching the carbs...after the first mile or so of boosting the carbs get ice cold and can have condensation building outside of them depending on ambient weather conditions. These are details I wanted to document here I've never found researching these setups. 

 

 

 

Edited January 28 by Dat73z

[Dat73z]

@240zturbo just to keep it simple and in one post, in my research there are ultimately 5 things seem to solve all turbo hardware failure issues: 

 

1. Upsizing hardware to M10

2. Inconel or high temp alloys

3. Some form of mechanical locking hardware

4. Do not overtorque materials to yield

5. Don't trap heat in

 

Edit: added 5 but again since this is a carb setup everything is conpromise

Edited January 28 by Dat73z

[240Z Turbo]

I've never experienced the issues you stated and other than my GTR, I simply tighten by feel and don't use torque specs on the downpipe or turbo inlet.  BTW, the M8x1.25 can torque to 26ft-lbs per the table  assuming the highest grade of "9T."  I have 160K+ miles on the EVO and more than 100K of those miles was an aftermarket turbo and never had hardware failure just using out of the bin bolts from Lowes.

 

I've also used the inconel shields on various projects (TT ZR1 & EVO) over the years and again, didn't have hardware issues.  I hope you problem is solved!

 

 

[Dat73z]

@240zturbo nice projects. Are the downpipe hardware exposed on all of them? I've seen people mention on roadracing forums to not run a turbo blanket or shielding over the hardware, I've been wondering if that could be an issue. 

 

It was a nice weekend and since I'm still waiting on parts for reassembly I decided to pick up some tools for next week. A set of 3d printed L seal install tools from my buddy and a flywheel holding tool so I can stop asking my wife/neighbors/buddies for help at random hours. 

 

 

Edited January 29 by Dat73z

[Dat73z]

It's a long weekend for me, and all of my parts are now finally in. So I kicked it off by installing my new OE Nissan RMS with the tool my buddy designed and printed for me. It's a really great tool to aid in the perfect install. 

 

I'm going to see if I can get the car completely reassembled this weekend, a few things per day should do it. Tonight I'll see about finishing up the turbo hot side. 

[Zetsaz]

On 1/29/2023 at 12:13 PM, Dat73z said:

@240zturbo nice projects. Are the downpipe hardware exposed on all of them? I've seen people mention on roadracing forums to not run a turbo blanket or shielding over the hardware, I've been wondering if that could be an issue. 

 

It was a nice weekend and since I'm still waiting on parts for reassembly I decided to pick up some tools for next week. A set of 3d printed L seal install tools from my buddy and a flywheel holding tool so I can stop asking my wife/neighbors/buddies for help at random hours. 

 

 

 

 

 

Where did you get the flywheel tool? And any chance you can share the file for that seal tool? 

I've had a notorious leak that I'm almost positive is the rear main seal so I may be doing this next time I'm home. My brother wants the leak fixed so he doesn't have to have cardboard under the car when it gets stored at his new house haha. 

 

Debating going with a lightweight flywheel while I'm there, but since I'm making less money now (though saving as much with fewer expenses) I'm avoiding too many "mid cost" sort of items so I can save for a major brake upgrade down the road. 

[Dat73z]

@Zetsazthe flywheel tool is a lisle 23800, I got it new on Amazon for like $30 delivered. 

 

The seal tool my buddy designed (this is actually v3, I have all 3 of his prototypes lol). I could give you his contact info if you're on IG not sure if he's selling them but I can vouch his stuff is really quality/high resolution. 

 

I posted some pics earlier in the build but it was pretty apparent by the way the oil was being flung out from the flywheel when I took it off that the RMS was for sure leaking so i replaced it. Check the side seals too. But it's kind of annoying cause you don't know for sure if it's all fixed until it's all back together and running lol

 

 

[Dat73z]

Today ran away from me somehow but I'm starting back in on the build now. My wheel faces arrived in from Japan so I started measuring for the barrels. I'll need to get with my builder on Monday to figure out some particulars on the hardware dimensions as everything is tight with the big brakes. I had already swapped in shorter springs earlier in the build thread and camber hats to run 245s with no flares. 

 

Since I need more data to proceed I'm getting back into the turbo assembly tonight. I'm really hoping I can get through that soon as it's literally just bolting things together after that. 

[Dat73z]

And one more shot of the turbofans on the turbo build. The front brake clearance with spacers will be the limiting factor here. If I was running smaller or stock brakes then there would be a lot more options. Otherwise 16x8.5-9 will fit easily on the rears or 245 or wider tires with the suspension modifications. I want to run everything square so I can rotate tires

[Dat73z]

This weekend ran away from me but I'm starting back in on the build now. Where I left off I had reassembled the turbo with all new hardware and safety wired all of the inconel shielding back into place, replaced the RMS, and reassembled the clutch pack also with all new hardware. 

 

I think the objective this morning will be to shove the trans and driveshaft back in. If I have time this PM I'd like to rehang the exhaust. 

[DuffyMahoney]

Love this build.  

[Dat73z]

Thanks @DuffyMahoney. It's been a journey for sure. 

 

This afternoon I fully reassembled the driveline and filled the trans with some Amsoil 75w-90. I was going to mount the exhaust but it started raining so I decided to put the car back down and torque down all the suspension again. 

 

No sense in rushing at this point as the car's been down for 2 months and basically had the suspension, driveline, brakes and turbo fully serviced along with some upgrades. The plan is to hit everything with a wrench one last time and shake down the car over this week if the rain lets up. 

[Dat73z]

Today I started by writing down what I did over the last few months to rebaseline what needs to be done next and also for tuning. I realize I need to go through and write down all my jet settings again as my memory is foggy at this point: 

 

1. 40 -> 45 pump jets
2. 1.8 -> 2.5 needles and seats
3. Cut and reweld hot side charge pipe
4. 170 -> 160 tstat, modify tstat housing
5. New BHJ dual row damper + 10.9 bolt
6. Uprated inconel wastegate hardware
7. New valve cover gasket
8. New front and rear main seals
9. Uprate all boost control lines 4mm -> 6mm
10. Poly trans mount
11. Bead roll cold side charge pipe
12. 275 short rear swift springs + helpers
13. T3 camber top hats

14. New flywheel and PP hardware, new pilot bushing

15. New rear DS wheel bearing, repack and retorqure both rear stubs with new ZX nuts

16. Engine filter, oil, trans fluid, coolant

 

Still left to do: 

 

1. Brace midpipe

2. Finish barreling wheels for 245s

3. Meth injection

4. AC

5. Accusump

Edited February 6 by Dat73z

[Dat73z]

So after going through the suspension I found a few fasteners loose that I know for sure I had torqued multiple times in the past. Nothing safety related but just random things like the fuel filler plate and others. 

 

One thing I've been struggling with this build is random fasteners seems to be vibrating loose over a few thousand miles. I never had these problems for years of hard driving before building around the turbo stroker. I think I need to start drilling and safety wiring everything, along with checking torque on everything every few k miles. 

Edited February 6 by Dat73z

[calZ]

What type of suspension bushings do you have?