Turbo Conversions - Current Status
 

All that have done turbo conversions to your once NA cars: How are things still running?

How many years since your conversion?
Any issues:
Transmission holding up (915?)
Turbo oiling issues?
etc...

Although not very long ago, I did mine around October 2015 and all is still good. I regularly track it (detuned from .5 to .3)

I still have my 915 transmission, but I certainly baby it to some extent.

I know a lot of you did this conversion many years ago and am wondering how things are holding up.

Kyle

Mine is still going strong with no issues to report, other than a slipping clutch disk in the 915. That is probably what is keeping the 915 together at this point.

I have no leaking oil / smoke etc ... only the urge to turn up the boost which is currently set at 7psi :D I have a G50/01 on the bench and am planning to install it in the next year or so.

Cheers.

Sandeep

How old is your build and how much HP are you pushing? It looks like you have a similar build to mine.

I've had the turbo conversion going since summer 2015 ... making 300 RWHP / 300 RWTQ at 5000 rpm but the dyno chart drops from there due to the slipping clutch. I'm worried if I replace the clutch / PP with something stronger, I might damage the gearbox.

I use the car on the circuit as well as autocross at 7psi with no issues.

Cheers,

Sandeep

Mine had been converted for over a decade. No problems other than my tuning (too much timing) and engine assembling shortcomings (oil leaks).

Will be ready to finally go to the dyno here in the next couple of weeks, but for now on a very conservative timing map and rich fueling, it is running great. Did have an issue with the scavenge pump configuration but that has all since been sorted. I do only have about 200 miles on the engine since turbocharging so there is still (hopefully) a lot of miles ahead of me.

I've been kicking around the idea of turbocharging my 1980 3.0 and moving it to my '77 widebody. I have a BMW race car running a 1.8 ltr. motor that I've turbo'd and is controlled by MSII 3.57. I've already converted the 3.0 to EFI with the Bitz kit as well with MSII.

Any recommendations for spec'ing and sizing the turbo? Or any links to build threads I should research?

Thanks!

I've had mine converted since 2012 but started with a turbo engine so less of a conversion more a swap I guess however I did use the original 915 from the 76 build year car. It was a 8/31 r/p trans not the shorter one but soon as I raised boost to .8bar I started to see issues with the clutch (225 sachs sport) It did hold for a year though. Bought a centerforce which used a steel pressure plate which changed the rev nature enough I didn't quite like it as much but it held......enough to break a second gear set in the then almost 40yo transmission. I bought another trans and continued for a few more months maybe a year trying to baby it more but having a hard time with self control.....Broke another second gearset. I bought a lightly used 930 trans and tried to make it fit..couldn't make it fit (just one inch point one!) so I bought a short 930 and stock clutch set and it went together very well. Enjoyed the way I could hammer it with reckless abandon....well actually the stock clutch limited that a lot because it just couldn't hold over about 375-400hp.
Well something went wrong with my 930/51 so I traded it for a built carrera engine (3.3 cylinders and je 8.1/1 pistons sc cams ets..) with carrera manifold and new efi system and gt3582 turbo. With this new setup the stock clutch could not hold more than .5bar boost so I have removed the engine with only about 300 miles on a fresh build and 15quarts of liguid gold (mobile one vtwin) to again replace the clutch system and swap in favor of light weight 934/5 clutch and an aluminum flywheel. Should be back together tonight:)
During this time frame the car has gone through so much change that many friends or acquaintances think Iv'e had four cars. It went widebody and changed color.

I admit that I would not have had to make many of these changes if I would have not become addicted to boost..it's a sickness and I have it. If I had been able to control my urges and stay away from the pipe the original setup would more than likely help up much longer.
These cars and their 915 gearboxes are a kick to c\drive even with only .4-.5 bar!
If you can keep them down with .3bar efi or .5 bar cis then you'd more than likely get lots more life between clutch or trans issues.
Id do it all again too, Maybe a little differently I guess knowing what i know now but end result, I love.http://forums.pelicanparts.com/uploa...1534267540.JPG
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Not sure why I can't straighten it up...

Brando, I really like how the intercooler peeks out of the lid, looks cool. So I went turbo early 2012 but before that ran a Paxton supercharger for a few years. Ive been using the same rebuilt 915 the whole time but I do baby it. So far everything is holding up well but as I said, I take it easy on the gearbox and really don't drive it too much.

Thanks Rod, I did too but made the permanent change to a much bigger inter cooler and enclosed it with bigger tail. In the beginning I wanted to avoid the tail look but in the end gave in to the need for inter cooling ease.
BTW your car truly is beautiful.

These engines seem to take the conversion quite well as long as the boost is kept under control. It's the 915 that's the issue. I too, am now hooked on boost. Before my conversion, I knew nothing about turbos much less driven a car with one. :)

BTW, nice looking splitter. Did you make that?

Over a decade on mine. Just had the 915 rebuilt, but it was due to a friend missing a shift, it had 150k on it anyway, and had notchy 2nd gear. I don't baby the engine but am careful with the trans.

.5 bar Protomotive kit. Thinking about adding water injection and MAF, Todd can still supply both, and going to .7 with a more modern turbo.

Aside from quattrorunner's clutch experiences with a 915 above, what type of clutch / PP system are others on this thread running ?

I have a slipping clutch (stock + carrera 3.2 PP) that I have to deal with this winter, but not keen on blowing up my mostly stock mag 7:31 915 with upgraded diff side cover. My end goal is a G50/01 that I have but still a long way off from collecting parts.

Any thoughts on this ? Most of these builds seem to be in the 300 - 350 hp range.

Cheers,

Sandeep

I turbocharged my 2.7l last year.

Most of the miles I have on the conversion have been from tuning and sorting out issues, but so far, so good.

I'm running around 8 psi.

I haven't had it on a dyno, so all I know is that it is making a LOT more power than before.

IROC 912
I bet your car is a riot!
EFI gt3076r 3.2 carrera and close ratios make for a car that can outrun almost anything to 125mph.

KEP stage 2 in my G50

Sachs 915 "Power Kit" is a stock clutch cherry-picked off the line for top 10% of holding power. It'll seem OK with RoW power levels (930/60 == 300 HP) or slightly modified (+SC cams & open exhaust == +10%), but you'll have a service life of ~12-15,000 miles on a friction plate - e.g. you'll find to your surprise that you're down to the rivets when you drop to address something else.

I believe it actually slips at these power levels (hence the premature wear), but not so badly it's obvious and you notice.

Increase power significantly (e.g. bigger intercooler, K27/HF, headers), you'll be in the ballpark of 370 HP, 350 ft/lbs at the wheels - and a car that responds progressively to throttle - e.g. makes boost below 3000 RPM, like 6PSI @ 2400, given load.

You can't even progressively break the motor in with a (new) Power Kit at these levels - it'll very obviously break free and begin polishing the flywheel (e.g. it'll just get worse, and very quickly too) at any more than half-throttle in boost around max torque.

The good news is that a kevlar 6-puck clutch and an Sachs "Competition" RSR-style pressure plate will hold these power levels just fine.

There is, however, downside. Firstly, the increased spring/clamping pressure broke, one-by-one, break every aged part on the outside of the gearbox; actuating arm, bracket that holds the cable etc. - Save yourself the trouble and just replace them off the bat. I got pretty tired of hearing "huh, never seen one fail like that before"....

The puck clutch wants to be in or out. It'll complain/chatter loudly on hill starts or reversing up your sloped driveway, or anytime you're forced to slip it for more than 18" or so...

Stock 915 clutch, you can depress the pedal fully with one hand while lying with your head under the dash (e.g. at an awkward angle).

Competition PP? Ha. Nope.

The pressure plate will feel like a leg press after about 10 minutes in stop-go traffic, after which time you'll start to become seriously concerned as to whether you can continue to provide the finesse needed to slip the puck clutch, your leg will be shaking so much. After 20 minutes, you'll be audibly cursing.

The stock(-ish) 930/60 ate, chewed up and spat out my original '77 mag gearbox. The 5th gearset was dark blue, spun bearings, a real mess inside. Seemed no point rebuilding it - pretty clearly not up to the task.

A 7:31 C&P with a mag box and a 930 (or equivalent power/torque levels) really seems to be pushing the envelope a bit to me, as the 7:31 isn't considered advisable with a 3.0 SC...

I went with an '86 915, plate-type LSD (also a strengthening factor), WEVO bearing plate, factory cooler pump and internal oil bars, new bearings, synchros etc. And the clutch arrangement mentioned above.

It was lovely to drive, really nice... 915's will shift into 1st at 30 MPH without double-clutching if you really want to - although you'll not make a habit of it when you look at the price of the synchro's this wears..

One day, the 930 was bored and decided to eat 4 teeth off the 2nd gearset (which was both tall and kinda old); wasn't even trying at the time.

Being mindful of the transmission and it's weaknesses seriously interfered with the fun factor for me, until I went G50.


HTH.

Yes, the G50 is a tough transmission on par with a 930. The diff is weaker, but you can put a billet diff cover on for additional strength. Then you’ll never have to worry about it.

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 :confused:

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

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 :)

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: http://forums.pelicanparts.com/911-930-turbo-super-charging-forum/774956-915-turbo.html

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.

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...

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...

.5bar on an '86 3.2
 

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!!

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Woah really cool

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:rolleyes:

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.

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......

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.

sweet!

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

found another cool picture
 

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

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..

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

DSM, love the duel out exhaust.

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

I did, now I'm widebody..

Is it completely stock?

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.