3.2 Turbo conversion - OEM or aftermarket?

[Bergo]

Hello,

I recently acquired a stock 930 turbo setup, minus intercooler (turbo, wastegate, heat exchangers, muffler).

since my car will never be numbers matching anyway ('74 turbo widebody look, planning to swap in a 3.2 and turbo it) , am I better off selling my stock 930 parts, and just using aftermarket parts for my car? cost being the main concern.

[Matt Monson]

Aftermarket turbo parts are WAY more expensive than OEM components. However, aftermarket parts offer a much larger range of tunability. A lot of it depends on how far you want to go with the power. If we are talking about a nice moderate 300hp build, then doing it with stock parts is pretty straight forward and simple. If you want 500-600hp, aftermarket has huge advantages.

[Bergo]

Thanks Matt, goal is to shoot for 300-325 with a rebuilt 3.2.

I've noticed 930 parts prices (OEM) skyrocketing lately, as people return their cars to stock, wondering if used aftermarket prices will be surpassed by used OEM prices?

[spuggy]

Originally Posted by Bergo

planning to swap in a 3.2 and turbo it

Originally Posted by Bergo

cost being the main concern.

My $0.02? LOL. Back away from the car. Stop now before it's too late...

Sell the 930 parts; none of them are very useful for a 3.2 conversion.

3.3 turbos are a low compression/high boost, 300HP installation - and almost everything you list are the very first items ditched when going the 930 upgrade route - bolt-on a more efficient turbo, better headers and intercooler for better spool (more tractable/linear power) and 30% increase (~400FWHP). Many change to SC or 964 cams at the same time - but lots don't.

The stock turbo is awful anyway, primary reason for both the appalling turbo lag and running out of breath at the top (other reasons for that are the soft cams and puny 34mm intake ports). Folklore says the 3DLZ is an off-the-shelf part for a diesel truck; there are certainly far better alternatives available now.

The factory wastegate works great. But the stock spring is .8 bar (much too high for your purposes without lowering your C/R) and rebuild kits hard to come by. You can't just cut a spring in half to halve the rate... Many folks just replace the factory WG with easily tunable/rebuildable aftermarket items like the Tial F40 - which is a direct replacement.

You can't use the H/E's from the 930 (exhaust ports smaller than the 3.2 exhaust port). You could probably use the J-pipe to mate up to the 3.2 exhaust system - but would certainly be better served with an equal length primary system.

Unless you're prepared to replace the pistons with low(er) compression ones, what you're probably looking for is a low boost kit as bolt-on as possible, perhaps with a rising-rate fuel regulator and a map or piggyback unit for the Motronic. (Or, preferably, in my view, ditching Motronic and going with a management unit that "understands" boost - like anything designed in the last 10 years or so)

Promotive used to do several kits. Think their Stage 1 ran around 5-6 PSI (yields somewhere around 350 HP, from memory) for $5-6000 or so. Non-intercooled, IIRC - and pretty much bolt-on, no need to open the motor. Although I'm personally a huge fan of ARP rod bolts for the 3.2/3.3...

There's a detailed write up of fitting/running Promotive's kits on this very board. I must have that saved.... Here you go, from 2004 http://forums.pelicanparts.com/porsche-911-technical-forum/176597-protomotive-stage-install-part-1-a.html



A low-boost 3.2 should be a hoot; exactly the same as an N/A car, just add a fast-spooling, low-boost turbo like a small-frame BW or Garrett - you would be in boost anytime you hit the accelerator with some load..

And 3.2 & 964 motors are arguably a better starting platform for a high-output EFI forced induction car than the 930 itself, as you end up throwing less away.

But if cost is a factor, that's kind of a red flag. Step away from the edge. Nothing about this is cheap to do it right...

Once you go significantly over 300 ft/lbs, it's thin ice for the 915. Clutch selection & transmission longevity/build becomes an issue. Even at 300 ft/lbs, you really want some WEVO bits (side cover/bearing retainer) and an LSD - and my Power clutches didn't last very long... With sticky wide rubber at the back, you could kill it with a bad launch regardless of how much you spent. And with money a factor, you don't want to know how much 930 or G50 conversions cost.

You'd also probably want to look at suspension/brakes...

[Bergo]

I'll be rebuilding the 3.2 with lower compression pistons and 964 cams, and putting an LSD into the transmission.

Goals are modest, ~300HP, I'll be doing EFI w/ MS3. budget is around $10k, which based on my reading should be ballpark, but it's not a hard limit. Car currently has a 2.2T in it, plan is to put it on the shelf when I'm done building a turbo 3.2, so there's no rush.