Turbo or not?

Matysiak · 10-04-2011, 05:24 AM

I have a ROW 1982 targa (9.8 compression ratio). The car has had an EFI conversion using a 3.2 inlet manifold, branched exhaust and runs an aftermarket fully programable ECU. On the Dyno it recently made 207 HP.

The problem is my daily drive is an E60 M5 and although this targa is fast, it's just not fast enough. Now before everyone says sell it and buy a 930, that's really not an option here in South Africa ( Johannesburg - 4500 ft altitude) as right hand drive 911's are few and far between.

So, to my question, is it possible to put a new set of headers on (Seen on Flea bay for 400 USD), a small turbo (400 USD) to keep the boost levels acceptable and possibly an intercooler, only looking for around 300 hp. I know i would need to fabricate an oil feed for the turbo, but have seen it done from the pressure switch on the forum.

What am i missing? Seems like i could turbocharge the car for +- 1500 usd.....

pkracer21j · 10-04-2011, 06:39 AM

my guess would be that your pistons have too much static compression to run boost, even low boost. maybe they would work with twin plugged heads, but more then likely you'll need low compression pistons, 7.5:1 or so.

Tippy · 10-04-2011, 07:03 AM

Ask or do a search in the 930/Supercharging forum. There are quite a few 3.0 turbo'd cars there.

Rodsrsr · Rodsrsr's Garage

I just did this conversion on my 84 3.2. Although the US version has slightly lower comp, I still think you could do it, just keep the boost lower. Your costs are way off though. You need a wastegate that will take a lighter spring than the factory one, you need return lines and scavage pump. (some use drain method, but it doesnt always work) a turbo muffler and you also need to address ign retard in relation to boost and additional fuel. Lots of fabricating too. By the time your all done it will be at least $4,000.

Matysiak · 10-04-2011, 10:22 AM

The ecu I am running is fully programable via either the map sensor, tps sensor or lambda. I can vary the Timing, fuel etc according the the vacuum.

I have seen t3 turbos with integral waste gates rated to 350 hp for 250 usd (wastegate is set at 8 psi) and the exhaust manifold for 369 usd, yes it doesn't have a heating portion, but it isn't needed in sunny South Africa.

Good point about an oil return, where did you feed it back into the engine?

Tippy · 10-04-2011, 10:25 AM

You can gravity back to the chain housing or drain to the oil drain plug using AN fittings and braided hose.

nkotselas · nkotselas's Garage

Rodsrsr is right, the cost will usually be multiple times what you are hoping for. All the small stuff adds up. It'll be hard to run too much boost, and even if you manage it, say goodbye to your transmission. 915 is quoted to handle 350 horsepower but with all the torque from a turbo you will be pushing the limits very fast.

You will then need to get a g50 or another stronger transmission for about $4,000 alone. I would just say lighten it and give it a good suspension.

Someday you should buy a real turbo (I know you said not to bring it up) but you can pretty much have endless power. The 3.0 will be limited and I would expect shorter engine life. I say save your money!

masraum · 10-04-2011, 05:09 PM

At 9.8:1 comp, I would think that even 8psi would be too much, but then I'm no turbo expert.

I agree, my experience has been what I've heard in the past when speaking of auto projects. Take whatever budget you think the project will cost and multiply by 3. Of course, you're talking about a Porsche, so the multiplier will probably be larger.