Rebuild of 3.3T to 3.5NA
 

It's time to rebuild my trusty 3.3 Turbo 930/60 and I want to do the work myself. But here's the catch. I never liked the feel of the turbo motors. I want something that feels more like my previous 71 2.2S. I love high lift cams and lots of overlap. I loved the throttle response of the webers on that 'S' motor. Lumpy idles and webers don't scare me. I have both of Wayne's books and Bruce Anderson's as well. I do all the work on my car but never rebuilt any motor before unless you count my Sears lawnmower :-) Based on many posts I'm leaning towards a single plug 3.4. But I don't know if this is possible with my current motor and I don't know what the pitfalls with this conversion will be. All help and advice is appreciated.

Most people recommend twin plug when using 98mm or larger pistons (3.4). Since it's a turbo motor, I think the 3.5 liter would be better suited, so you're getting as much power as possible.

The ports on the turbo heads are too small for a NA engine so you'd also need to look at getting Carrera heads or opening up your 930 heads.

Sure - should be easy, but not cheap:

- 'mod-S' cams
- PMOs or Webers, or TEC-3
- JE pistons
- SSI exhaust

-Wayne

I believe it's much simpler/cheaper/smarter to sell your 3.3T engine and buy 3.6L naturally aspirated one.

That being said, I bet you are going to be dissapointed in the end, when you find out that even EFI/twin plug/3.6L engine has less poke than turbocharged one.

You can build a turbocharged engine with good responce too. It just takes some know-how.

Thanks for the info. I have some research to do and I'll probably come back with questions over the next few months .

I agree with Goran.

A normally asperated motor has great throttle response, but in no way has the potential or rush of a turbo, especially a built turbo.

Tinker

Hi Tinker. I agree with you and Goran but max hp wasn't my goal. I was hoping I could match the 320hp I have now ('92' C2Turbo). While getting far better throttle response, feedback, and save a bit of weight while I'm at it.

I was going to suggest trying a 5 speed but I guess you already have that. I thought about doing this on my 930, but I decided I wouldn't be happy without the turbo.

You could change to 98mm 8:1 pistons and cylinders. This would help some.

If you decide to go NA, I would suggest swapping for a 3.6 since your engine is relatively new. You might even find a 3.8 RS motor or build one from a 3.6.

higher C/R pistons (8:1 for example), well-maped EFI (slightly less advance at low revs for quick spoolup, accelleration enrichment), two smaller turbos and throttle bodies will give you very responsive engine with 100-150 more HP than any N/A one will make. It's quite expensive though, but not much more than tuning high-strung N/A engine.

Thanks for the feedback and info. My gut reaction is that I'll keep my turbo seutp and just go to 8:1 pistons, and a 964 cam profile. I appreciate the advice and help.

I just finished rebuilding my 3.3 turbo to a 3.4 turbo with 7.5 to 1 RUF pistons (98 mm). I keep the stock cams and CIS. The engine is more responsive at low rpms (seems to have more torque). When I had the heads redone CE cut them to accept a C2 turbo head gasket. This was a trick used by Randy Greff in New Orleans on his high compression race engine. With 300 miles on the engine, I'm getting ready to adjust the valves and take it to the track in a couple of weeks. I'm sure a cam and turbo change could do even more.

what turbo did you use victor?

I just stayed with the stock turbo. But, the stock turbo is old technology. There are better turbos out there.

I just did a valve adjustment on my car this weekend. It's the first one I've tried to do with the motor still in the car. I almost think it's easier to take the motor out to do it :-)

I finished the valve adjustment yesterday. With all of the turbo hardware it is very tricky to get to some the rockers. I removed the intercooler, the air intake, the large hose from the intake to the recycle valve, and moved the AC compressor out of the way. Even on the bottom (exhaust) valves I had to remove the wastegate to get the left side valve cover off. Wayne stated in his book it would be more difficult in the car, and with the turbos, that is an understatement.

Congrats! I'm tall with big hands and for me the best way to do it is to also remove the engine sheet metal on both sides and do the uppers from underneath the car. The good news is that while I had the wastegate off I replaced it with a new Tial unit I've had sitting in my garage for a few months. I haven't driven the car yet but maybe today. The other up side of this tough proceedure is that I've gotten pretty good at dropping the motor :-)