Turbo the SC 3.0 or Source a 3.3L???

jcc911 · 01-28-2009, 08:21 AM

Guys,
I have been going back and forth on this daily and need some advice on which route to take in order to finally have a turbocharged 911.

So the question is do I TC the 3.0L with a 930 CIS, MK 993 header set-up and muffler, and K27 (plus all of the add ons like fuel pump, oil drain/scavange, etc)

OR

Source a 3.3L?

The one good thing about my current engine is I recently did all of the head studs and a top end (Thanks for the help M&K). I ported the heads for twin plug (that is not currently in use), and many of the components have been powder coated to my liking.

Obviously with the 3.3L I would have an engine already tubocharged and was set-up to do so. I may have found one of a reasonalbe price, but some assembly is required. Also I would probably have additional expense with headers, turbo, but this could be done down the road.

Thanks for the advice! Cheers.

BReyes · BReyes's Garage

Well, would get managable CR, 930 oil pump, squirters. Doing a top end to it and buttoning it up would give more power.

Regards,

patkeefe · 01-31-2009, 06:03 AM

If I had to do mine over again, I would go with the 3.3 as a starting point.

jcc911 · 01-31-2009, 06:47 AM

"If I had to do mine over again, I would go with the 3.3 as a starting point. "

Why?

patkeefe · 01-31-2009, 07:00 AM

Where shall I start?
Oil drain issues...there is no factory turbo scavenge pump for the 3.0.
The main oil pump, especially the scavenge side, is much stouter, so you can send oil out to the coolers more reasonably.
I really think there are detonation issues with the SC pistons.
Distributor has the vacumm advance and retard on a 3.3 (maybe)
Airbox on a 3.0 is flimsy, they all leak. The turbo intake system is much stouter.
SC injection system will not support full fueling at higher RPM. Yeah, you can make it work OK as a street car with additional injection, but you have a tough time emulating the factory turbo fueling setup.
You can search my username, I have a lot of documentation out there for posterity.

Also, I think a lot of my problems would never had shown up, if I had just kept it off the track. However, it's a Porsche, and they are made to go fast, so they have to be track-worthy.

jcc911 · 01-31-2009, 07:41 AM

Pat thanks for the info.
My intent is to buy a Euro 930 CIS, port it to match my SC heads, and use all all other factory 930 intake, intercooler, scavange pump. KKK TC and oil catch.

Unless I am mssing something, the only difference I now see is that I will have a slightly higher CR 8.5 to 1 with the SC P/Cs and SC oil pump. I will also have to add a fitting my oil tank for the scavange drain. It will be a low boost set up ~5-7 psi. Hopefully this will work out as I thin I am going to go this route, even though the cost is very similar both ways.

Thanks, Any additional info would certainly help as I am really far from being an expert.
Thanks again.

JohnJL · 01-31-2009, 03:26 PM

If you ever plan on selling it you will not recoup the investment, actually likely lose value.

However its a fun project but very very involved.

mb911 · mb911's Garage

with all the past history this is easily managable with 930 cis, use a factory scavange pump or an electric if need be. we need to learn from eachothers mistakes

jcc911 · 02-01-2009, 05:13 AM

Thanks for all of the info.

As far as scavange pumps go, how is the pump driven off the cam? How far do you have to tear into the engine to hook this up.
I also have considered an electric one.

jcc911 · 02-01-2009, 05:15 AM

Well I am on that bobsled down as I sourced a very nice Euro 930 CIS with only a few thousand miles on it.
It was pulled to go EFI and at the time the car was putting down almost 400 HP at the wheels.