3.0 to turbo

[khyden]

I have a 3.0 engine in pieces. My plan is to complete it and put a turbo or twin turbo on it. But could somebody give advices on this job. Something around 350-400 hp would be the goal on power output.

Kris

[Natchamp]

do this....

[khyden]

Huh, thatīs one great looking engine and car! Iīll read about your project during the weekend. However I bought a set of used 3.0 turbo cylinder sets. One is slightly damaged, so I must check.

Kris

[cstreit]

...assume you are talking about a 3.0L SC engine right?

There are plenty of low-boost type designs that you can look at... At 350-400HP you should also think about transmissions. That would really be pushing the limits of a 915 gearbox. The 4 speed turbo would handle it though...

[khyden]

Yes, a 3.0 SC engine. Bought it without a gearbox, so Iīm thinking either G50 or six-speed from 993, if possible. However four-speed could also be interesting. My masterplan is to do the engine during this winter and during next summer get a rolling car. I have also started buying parts (brake and suspension).

Kris

[philippeF]

ask "beepbeep not far from you : sweden, his a master for turbocharging...
Philippe

[iamchappy]

I am rebuilding my 79sc 3.0 engine for turbocharging. I have looked at some of the options, I think I would like to use 935 pistons. Are these a fairly straight install, what compression ratio should i expect from them. Are there any drawbacks in using them.

[Bryan Beaumont]

Henry at SUPERTEC built my motor with 935 pistons. So far, so good. The only draw back is that at cold start up there is a little bit of piston slap because of the design. Once it heats up a bit, about 2 mins., you can't detect it at all. Compresion ratio is 7.5 to 1. My car runs incredible. Pulls like an SC down low, and like no 3 liter I have ever felt up high. Too much fun in a light weight car.

Bryan

[paulweir]

Actually the 915 gearbox is plenty strong. I have a 1977 turbo look targa street car with a 375 hp 3.5 RSR engine (factory slide throttles and twinplug distributor, 935 crank and titanium rods, all titanium valves, 9200rpm redline, etc etc etc). I have a stock magnesium case 915 trans (pretty light compared to a G-50) with LSD and have driven it for over 10 years with never a problem. Actually the 930 4 speed trans is not very interesting at all, in the past I have taken them out of 76 and 77 930's and installed aluminum case 915 transmissions which worked much better. I also have some 935 pistons and many other 935 and 962 engine parts.

Paul Weir "Porsche Engine Expert"

1411 172nd ST NE
Arlington, WA 98223

Tel & Fax 360-652-5962

[iamchappy]

Is the 935 piston slap the cause of the stroke angle being different because of the pin location or piston skirt.
I may need to start looking for some other options for pistons again. The 3.0 turbo pistons maybe the best alternative for me or go back to using the stock SC pistons and settle with low boost.

[Bryan Beaumont]

The very minor slap is simply because of the slightly greater tolerances that Porsche designed these to. For heat reasons, I believe. Very minor...and only when cold. NO NEED to look elsewhere, this setup is bullet proof. Think about it....1.1 to 1.4 bar for 24 hours running at a consistent 7500-8000 rpms in the 935's. If you can get your hands on a good set--use them. How about some trick 935 Titanium rod bolts, while your at it.

Bryan

[Henry Schmidt]

The piston slap in a junction of short piston skirts and racing tolerances.
The 935 was never meant to last must more than 24 hr. and loose tolerances represent less friction and more horse power.

[iamchappy]

I have a line on a set of NOS 935 pistons complete with rings and pins and it looks like Paul has some. I will stay the course then and go with the 935s as planned.
I wish I had sometime to visit with you Henry last Thursday I had more to do to get ready for our art show in Rancho Santa Fee on Friday than I had planned for.

[iamchappy]

Are these the real deal. And what are they worth, sale is pending.
Full set of NOS Porsche racing pistons for late 935, 956, 962. Complete with rings and pins etc.
3.0 ltr 24 valve racing pistons , Number on top reads - E_ 62/4_ 0 and part No hand written 935 103 31403

[Henry Schmidt]

These are 4 valve pistons and if they are 95 mm I believe you'll find that installed on a 70.4 (911SC) that comp. ratio will be entirely too low.
I would look for a two valve set of pistons from a hi comp. 935.
They had a slight dome and valve pockets so valve to piston clearance is not a problem.

I probably have some 935 pistons and cylinders that I would part with.

I also have some (2 sets) 962 Ps & Cs that are 92.3 mm (2.8 on a 3.0 crank) these have a 22 mm wrist pin and on a 66 mm crank made 7.5 to 1 comp. On a 3.0 (70.4 stroke) they should make just over 8.0 to 1 . These cylinder walls are so thick that they could easily handle 1.4 bar of boost without distortion.

[paulweir]

Those are real but for a 4 valve 4 cam 956 or 962C racing engine not a 2 valve 2 cam engine. I have many of those pistons (and cylinders) and all are 95mm

[iamchappy]

Henry and Paul, could you please check for me if you have any of the correct 2 valve 935 pistons in good condition available.

[Henry Schmidt]

I have them you just need to figure out which way you want to go.
Cheers.
High comp 2.8 Turbo in a 914/6 sounds pretty cool and very rare.

[fintstone]

Originally posted by Henry Schmidt
I have them you just need to figure out which way you want to go.
Cheers.
High comp 2.8 Turbo in a 914/6 sounds pretty cool and very rare.

Henry
What exactly is a High Comp 2.8 turbo? What is the compression and what engine do you use as the base?
Stoney

[fintstone]

Sorry, I found the other thread!