I have just purchased an 89 S2 from another local rennlister. The car is distressed with chain tensioner failure and fairly high miles. BUT, the interior, body, and other mechanical and electrical are flawless. A beautiful car overall. Here's my question. I want to turbo"fy" this car, what's the best route for me to take? I have a complete wrecked '86 turbo and another 'beater' '86 turbo I am trying to get up to par. Would a rebuild of the 3.0 and install of the 2.5 head and intake be doable? What mods to the lower end of the 3.0 would be necessary? Or should I just pull out all of the S2 stuff and go 2.5? Either way I need to rebuild the engine that ends up in it because both have higher miles (2.5-150K & 3.0-225K) I will be going with stand alone engine management for sure, so that part doesn't concern me.

 

Putting a turbo on the 3 liter would be a major undertaking. Not the least of which would be lowering the compression, which would require a custom set of pistons. Check with John Milledge <a href="http://www.jmengines.com." target="_blank">www.jmengines.com.</a> I'm looking for a 3 liter if you're interested in selling.

Al Pyatak
apyatak@sprynet.com

 

sorry about the double post. Computer hic-up

IMO even with very little boost you'll hand-grenade, again check with some of the builders.


Al Pyatak
apyatak@sprynet.com

 

It might be a major undertaking but it sure would be neat. Maybe you could stick with the S2 pistons and run less boost. That would make the stock k26 a really good fit, as it can deliver 8-10 psi pretty efficiently. Lots of new cars run higher compression with moderate boost (S4, etc.) and with a programmable system I'm sure you could get it hopping along nicely. <img src="graemlins/jumper.gif" border="0" alt="[jumper]" />

 

Best and most cost-effective way would be to mix & match the two '86 951 drivetrains into the S2. Staying with stock parts in a stock configuration would give you the best reliability and drivability. Then when you're done, sell me the S2 engine!

 

Actually this conversion is very do able. My mechanic (Bauer Porsche in Oakland Ca). Has done a couple of these conversions. What he does is modifly the pistons and modify the 2.5l turbo head. He advertises in excellence's, give him a call. He compare the performance of 3.0l turbo to that of a 993tt. Good Luck

ken

86 951
79 930

 

What modifications on the Turbo head are necessary to line up with the coolant passage on the block? Do they just cut it off and move it down a bit?

 

Good point, Danno, I'm going to have to do some research into that. How was it done on the 968 Turbo RS? Does anyone know, or is it just a different head?

 

The 968 Turbo RS has its own 2-valve head...

 

Badue,

You should attend the "Great Danno, SFR PIZZA RUN" on Saturday the 23. That way you could ask the guys @ Speedforce Racing, they love a challange.

Go the the Water Cooled, 924/944/951/968 board and check out Danno's post "SRF - SoCal PIZZA RUN Sat 3/23" for information

Ken,

How about you, are you up for the run? We have a lot of guys from Nor Cal caravaning.

 

Regarding modifications necessary, I have a 2.5L turbo head that has been modifed by Albert Broadfoot with an adapter for the water passage difference. It will now bolt correctly to the 3L block.

I will show digital pictures directly. This is not difficult to machine.

Contact Albert directly for another opinion. Garrity can do the mod as well if you ask him.

 

Sorry Bill, but I have other plans at this time. I hope you guy take some picture and post them on rennlist. Unfortunately being married and having a 10 month old baby has it disadvantages.

ken

86 951
79 930

 

As far as the pistons go, can't you just use the factory 968 Turbo RS pistons (about $1500 I think)?

 

Yeah, the factory Mahle pistons are very expensive. Unfortunately, they are the only way to turbocharge a 4V.

If you swap the head from the 951, what's the point? You get a 3.0L 951 motor. He already has 2 951 engines, it would be an awful lot of trouble and money when it doesn't have to be.

I have talked to John Milledge, and he told me that when he turbos a 4V, he uses a cylinder sleeve and custom piston, among other extremely time and money consuming things.

 

Yeah, what we're getting down to here is that there's no simple bolt-on solution to turbocharging an S2/968 engine. Check out some of the other threads on modifying the 2-valve head to fit the 3.0l block.

Or even better, is to use both the 3.0l block with the 3.0l head. Since you're going to be making head modifications anyway, might as well do it on the better head. The 4v head flows about twice as much air as 2v head at high-RPM; you won't get that dramatically falling torque curve you see so much with upgraded turbo cars.

Since turbocharging places so much more stress on the parts, you're looking at replacing the rods, pistons and valves anyway. Do it for the most durability the first time around.