Triple Blowthrough Turbo

[Dat73z]

Weekend update: 

 

Motor is done going to see if I can pick it up next week after the holiday. 

 

I went through and powdercoated all the suspension maybe 5 or 6 years ago? Decided to finally degrease the engine bay and tidy things up. So far as I can tell it's mostly original paint given the completed faded paint code tag on the radiator support. Might consider doing a quick body color respray or at least scuffing and shooting any areas of exposed metal. 

 

 

 

[Dat73z]

Just about wrapped up with the engine bay prep and starting to unpack the other parts for the build. 

 

I'm planning to have my 240mm chromoly flywheel resurfaced + balanced and need to order a new clutch. I have brand new and lightly used exedy oe replacements in my parts bin but I'm pretty sure they won't hold 450+ hp/trq. I see OS Giken has a few options but they're pretty pricy and I'm not sure how streetable they'll be. 

 

Any suggestions on cost effective options? 

 

Edited May 31, 2021 by Dat73z

[Dat73z]

Pre-weekend Update:

 

Sold all my old clutch stuff and ended up ordering a OS Giken twin plate. Will need to modify my trans a bit but I'll get on that next weekend. 

 

Also managed to pick up the motor from Rebello today. Dyno sheet attached for reference. It's a 3.2 stroker @ 8.5:1. The f54 block, p90 head, and knife edged diesel stroker crank were spares I had in my garage that I didn't want to move when selling the house. Turbo parts from earlier in this thread. The other parts in the build like forged rods, pistons, bearings were all specified by Rebello. 

 

Edit: Realize the img is fuzzy. 10psi it made 359.1 Ft-lbs @ 4900 RPM, 370.2 HP @ 6100 RPM. ~11.5 AFR's, need to check the timing data, I think intercooler was heat soaking as well. 

 

Since the Mikuni short runner is ported out for my OER 47 carbs maybe I'll go OER 47 ITBs down the line.

Edited June 9, 2021 by Dat73z

[Dat73z]

Finished modifying my transmission input cover and flywheel bolts.

 

For the OS Giken dampened twin plate 4mm needs to be removed from the input shaft area of the cover, and bolts ~8-8.5mm head thickness. The bolts are actually around the same head thickness now as the 240mm turbo/2+2 flywheel bolts but I gave those to the buyer of my old clutch setup so they could bolt the setup right in. 

 

Next step is to finish prepping the turbo manifold and send the assembly off to ATP for their inconel heatshield treatment. 

[Dat73z]

Last post on the driveline prep before going back into turbo stuff although I guess technically this is prepping the driveline for the turbo. 

 

Didn't find much info on the OSG damped twin or triple plate setups online so hopefully this is helpful to someone looking into it and the modifications required. The OSG throwout bearing collar is extremely short, and the stack height of the clutch assembly relatively tall. 

[Dat73z]

Quick weekend update. Welding up some brackets with the tig. Pulled the manifold off for some other prep and checked the porting. The transitions look pretty good, they're ported out to 47mm at the carbs, reducing to the Nissan gasket size at the head.

 

Still waiting for some misc. parts to come in. This next couple of evenings I want to clean up some porting I did on the exhaust manifold before sending it out. 

[Dat73z]

Had a few mins this evening to keep welding things. I had a couple of mild steel an6 bungs that I boxed up before moving but I'm still unpacking and couldn't find them but I did find a stainless an6 bung and some 309L filler wire so I started on the turbo coolant feed. The plan is to keep the heater and feed the turbo from where the SUs used to and return back at the thermostat housing. I used to cap these off with a rubber plug but the rubber never held up for more than a year of commuting before cracking and leaking coolant. Hopefully this holds better. 

 

Edited June 14, 2021 by Dat73z

[Dat73z]

Started on finishing the porting job I started years ago. Will probably spend the next few evenings gasket matching and smoothing all the transitions. I'm gasket matching to the OEM Nissan gaskets. 

[Dat73z]

Wrapped up the porting. I didn't go crazy with it, but much better than when it ran on the dyno. The aftermarket t3 gaskets are much larger than the OE Nissan. Most of the time was spent on the manifold transition. Also opened the waste gate some more as it looked like there was some creep on the dyno graphs. Rebello noted they had to port the wastegate as boost was spiking to 14/15psi on the dyno towards redline and it made somewhere around 450hp on that run. 

[Dat73z]

Dropped off the turbo manifold to have it resurfaced about a week and a half ago and took a break to work on some house projects. Just got the manifold back over the weekend so I threw it together and torqued everything. The machinist noted it was banana'd out on the head side and somehow the turbo side was warped as well so good thing he skimmed it all on the mill. 

 

Putting it together was really time consuming but I hope it'll be worth it and the hardware won't come loose with some heat cycles. I used nickel anti-seize, grade 8.8 studs, oem nissan plate locks, nordlock washers, and copper coated deformed head nuts. 

 

Sending it out tomorrow for inconel heat shielding. 

[Dat73z]

Waiting on parts to get back to wrap up the turbo motor so I started back on random bracket and parts fabrication. I couldn't find a crank vent tube so I made one with a 10AN fitting. It seems like ~25mm OD tube is a good interference fit for the block breather. I went with 40mm length on the tube portion but I don't think the length is a critical parameter. 

[Dat73z]

Had a day off from work and still waiting on parts so I decided to reshoot the block. 

 

When I got the motor back the paint was flaking in places, some areas which didn't get enough paint and a bunch of overspray everywhere. 

 

I cleaned up the overspray with acetone then fully degreased the block and hit it with some red sanding pad. Blew it off, degreased, taped and used a tack cloth. I used the MSA Datsun blue paint and really liked the way it laid down. Not sure how it'll hold up but at least the flaking areas won't bother me anymore. 

[Dat73z]

Got the manifold back from heat shielding and test fit. Mostly looks good but I'll need to trim one small area to clearance for a yoke washer. Waiting for a couple of parts to come back in so more chassis prep for this next week. I'm trying to set a goal for myself to have the motor back in the car by August so I can start fabricating the exhaust. 

Edited July 10, 2021 by Dat73z

[rossman]

Lookin' good!  If you haven't already, you should consider porting the wastegate hole.  Make the ID of the hole about 2mm smaller than OD of the flapper.  Also round off any sharp edges where it transitions to the turbine. What is that material you are using for heat shielding around your manifold and turbine?

[Dat73z]

Thanks rossman. Yeah I noticed the boost was creeping on the dyno graphs so I ported out and smoothed the wg housing a bit more before heat shielding.

 

The shield material is some inconel alloy. I'm planning to use the same material to shield the carbs, downpipe, and turbo cold side. Hopefully it'll all help with heat managment. 

[Dat73z]

Got some parts back from powdercoat including some engine parts so started mocking things back up. For the vacuum log I'm going to try welding on a flat piece of AL on the bottom and slot some holes to bolt into the intake manifold. Maybe reserve the valve cover holes for a fuel rail. Still not 100% sure but got word on more parts delays this week so I've got some time to think about it. 

Edited July 15, 2021 by Dat73z

[DuffyMahoney]

Amazing work

[Dat73z]

Thanks DuffyMahoney 👍. It's been a long but rewarding project. I took a look at your itb build and it's given me a lot of inspiration. Lots of great attention to detail. 

[Dat73z]

Quick update, been busy with the chassis for this build but for the blowthrough turbo motor mounted the BOV. Feedback from Rebello was this setup needs to vent immediately transitioning off boost when the butterflies close or fuel throws up through the front of the carbs. I guess they experienced some of that on the dyno so maybe the upgraded BOV will help.

 

The last piece I'm waiting for before buttoning up the motor and dropping it in is the BHJ damper. Apparently they were backordered for a long time but mine came in so Rebello will be sending over. 

[Dat73z]

After some delays finally got the BHJ damper in from Rebello and so I mounted it up. I used a Volvo washer turned down to the same OD as the stock 240z crank washer and a Nissan KA bolt. After chasing the crank snout with a bottoming tap my measurements show I have maybe 2-3mm of threads left when using the thicker volvo washer so I won't need to turn the longer KA bolt down. 

 

This next couple of weeks the plan is to mount the rest of the accesories and get the full driveline back in the car to start fabricating the exhaust and charge piping.