Turbo Conversions - Current Status - Page 2

IROC 912 · 08-25-2018, 05:20 PM

Thank you for the detailed reply Spuggy ! My driving enjoyment is always hampered by the "What If" I launch it hard this time, will the gearbox hold together

I keep hoping the 915 will last but now realize it's definitely the slipping clutch that's keeping it together at the moment.

Need to search the want ads for some g50 bits now and also approach a local custom machining company for some quotes.

Cheers for the data.

Sandeep

spuggy · 08-26-2018, 10:53 AM

Quote:

Originally Posted by IROC 912

Thank you for the detailed reply Spuggy !

You're welcome! If I can save anyone 1 or more clutch jobs by sharing, just buy me a cup of tea or an adult beverage should we ever meet

Quote:

Originally Posted by IROC 912

My driving enjoyment is always hampered by the "What If" I launch it hard this time, will the gearbox hold together

Hahahaha. I can laugh about it now, but it was a big worry for years...

When you've been through 5-6 clutches and a couple of gearboxes in quick succession, "launching hard" on your eye-wateringly expensive 915 will actually be right at the top of your list of things to avoid at all costs...

Not a new problem; this old thread discusses some of the issues/limits: 915 and a turbo

You should actually be pretty much fine at your power level with a well-fettled 915. Ideally one somewhat stronger than a 7:31 mag 915 without the "standard" strengthening mods (LSD, stiffer cover, bearing retainer).

Which would be more-or-less OK for 300HP. Except if you want to "launch hard", or add significantly more power later. Either/both will still kill a 915 - and SBH G50 or 930 is the only real answer, I think...

It's also worth noting that Jack Olsen runs a mag 915 behind a tuned 3.6 - for years now - in BBII, and doesn't exactly treat it gently. But if you watch his videos, you'll note he has a cooler pump (in addition to the standard goodies), which he switches on when the transmission oil gets close to breakdown temperatures.

I've pondered if uncontrolled oil temps - and subsequent breakdown of the protective film - was what actually did the damage to the original mag 915 - the one with the dark blue 5th gearset & spun bearings - as the PO loved to go to the track and didn't run a cooler.

Quote:

Originally Posted by IROC 912

I keep hoping the 915 will last but now realize it's definitely the slipping clutch that's keeping it together at the moment.

Sounds likely...

Another thing to bear in mind; Matt (Monson) points out that all the 915 gearsets are very old now, and should be magnafluxed - or just replaced. Especially the ones that break (e.g. 2nd certainly, ideally 3rd). Modern metallurgy is vastly improved over the 70's...

Quote:

Originally Posted by IROC 912

Need to search the want ads for some g50 bits now and also approach a local custom machining company for some quotes.

Cheers for the data.

Sandeep

Converted G50s do come up used from time-to-time, just never seem to when you're poised to buy... Or, alternately, about 2 weeks after you start to convert one yourself at ~3x the cost...

Oh, and re-gearing really adds up - but N/A ratios are just stupid low...

chrisf · 08-27-2018, 08:54 AM

I did the conversion in april 2016. Garret T60 turbo running .5bar thru a small intercooler using a chip by Todd at protomotive. I am using VR1 20w50 full synth. It did begin to leak a lot when I first got it running, but I have been able to address the issues and it is now completely leak free....knock on wood.

The car is phenomenal to drive. An absolute blast and it just seems to run better every time I drive it. I find that I rarely use more than a fraction of the gas pedal travel. I can reach positive pressure by 2800rpm and full boost at 3200. It's a beautiful thing!

There have been a few occasions when I did use full throttle (only in 3rd & 4th gear) I noticed some clutch slipping. I am running a mag 915, original to the car ('76), which was fully rebuilt in 2008.

Couldn't be happier with the car!!

quattrorunner · quattrorunner's Garage

Woah really cool

patkeefe · 08-27-2018, 09:15 AM

My SC is progressing. I sent the trans out to get rebuilt and have an LSD put in. I got the car put back together and running again, and to my chagrin the transaxle leaks like a sieve when running in gear on jackstands in the garage.

I am spitting out oil through the top port on the SC oil tank. I thought maybe it is excessive crankcase pressure, but my leakdown numbers from Saturday are like 4%, and I don't think the rings are 100% seated yet. From what I can tell, these tend to spit oil from the top port (the one that used to go to the air filter housing).

I got the new EFI almost dialed in to run it in the garage, but I am going to need to get it in the hands of a tuner with a dyno to get it properly set up.

Along the way, I have had issues with the AFR gauge (it went bad, and I started to get crazy voltage readings in my oil temp gauge). Rewiring everything has been a nightmare, but I have it all figured out now, and labeled.

I think I need to relocate the return oil pump from the turbo, although this iteration of oil pump seems to work OK. The turbo sits too low to drain back to the sump on the stock 930 exhaust system (I scrapped the headers so I could have heat).

I really want to get this finished soon

quattrorunner · quattrorunner's Garage

Patrick you should get a catch can for that hose. My car is also spewing little bits of oil which it didn’t before the fresh engine.
Other than that you’re having similar issues we all do and working through them.

patkeefe · 08-27-2018, 11:26 AM

Yeah, I am trying to find a good catch can setup.

quattrorunner · quattrorunner's Garage

Quote:

Originally Posted by patkeefe

Yeah, I am trying to find a good catch can setup.

hard to find with 1" nipple......I'm talking about the catch can ronnie......

'76 911S 3.0 · '76 911S 3.0's Garage

Quote:

Originally Posted by quattrorunner

hard to find with 1" nipple......I'm talking about the catch can ronnie......

I actually found one with 1" barbs:

https://store.034motorsport.com/catch-can-vortex-breather-universal.html

$90 ain't bad either. It could fair to be about an inch shorter but it fits...barely.

quattrorunner · quattrorunner's Garage

sweet!

Uncle · 08-27-2018, 06:30 PM

My old blue 911 is still kicking about in another state. I think I finished it aroud 2012ish.

chrisf · 08-28-2018, 06:32 AM

quattrorunner · quattrorunner's Garage

That’s nice. It reminds me to ask if anyone has a 1bar or 1.2 bar waste gate spring?

DSM · DSM's Garage

Ran it last year a bit with 915. The tec3r performed great on the dyno and street. Running the auto VE feature really made it run better after every drive. 930 transaxle in now along with wevo shifter. Only drove it in my yard this year. Really close to completing the entire car. Has been a long journey..

Time zone · Time zone's Garage

New to the forum and would like to turbo my SC. What should a person be thinking about for cost? Doing this myself. Lee

cmcfaul · cmcfaul's Garage

DSM, love the duel out exhaust.

JH282 · 09-08-2018, 11:50 AM

Are any of you narrow body turbo guys having issues with traction? If so, how are dealing with it?Just curious.

quattrorunner · quattrorunner's Garage

I did, now I'm widebody..

flat6pilot · flat6pilot's Garage

Quote:

Originally Posted by Time zone

New to the forum and would like to turbo my SC. What should a person be thinking about for cost? Doing this myself. Lee

Is it completely stock?

gavinc69 · gavinc69's Garage

3.0, k27-7200, intercooler, 3.2 intake, efi, 0.5bar, 320hp. stock clutch and no slipping even with 315 section tyres. Gearbox has been ok but is very tired and is just coming out for a rebuild.