3.3 Turbo to 3.4 or 3.5 ? Help me Decide

Barracuda · 06:14 AM

Hello everyone, I am planning my full rebuild on my 91' 3.3T and most of my choices are already made up however I keep going back and forth on the P&C's

Option 1) Supertec 3.4 ...QSC's hand selected by Henry w/ JE's
Option 2) I go to 3.5 however Case machining required...Costs? I have no idea

Dilemna: Is it really worth it? I can tell you I am aiming towards a 550HP street monster with all the goodies including EFI but I am unsure if the 3.4 to 3.5 is really worth the trouble/costs. Any feednack would be GREATLY appreciated, including the pricing of Option 2 ...I already have a good idea of pricing for Option 1.
Thanks Everyone

PS: I want to keep the stock crank size

JeremyD · JeremyD's Garage

For a Turbo engine I would talk to Stephen Kaspar at Imagine Auto.

With a Turbo motor, it just depends on what you want to spend. I would also look at the sleeved cylinders that JB Racing has.

Lots of folks have been there done that -

Barracuda · 01-30-2008, 01:11 PM

Maybe I should add this, I am doing 90% of the work myself with the exception of a final EFI tune and the machining of the head work.

I am trying to decide if the jump to 3.5 will make a fairly considerable
difference, I realize their is more money involved and yes, I wouldn't mind knowing a ballpark price too. It's not really a matter of money versus a matter of gain...meaning if I could just take another route elsewhere in my build to achieve the same thing with less headache I may opt to go that route or if this would make a substantial difference overall I will deal with the cost involved.
Hope that came out right

JeremyD · JeremyD's Garage

In the days of the K-27 - you wanted to maximize displacement to gain low speed driveability. In the new age of bb turbos and performance pop off valves - Not sure that is as necessary.

If it were my engine - I would probably look at staying with the 3.4 slip in - figure around 800-1000 for enlarging your jugs.

The yellowbird does ok with the 3.4 - although that is a twin turbo.

AngM018 · 01-30-2008, 04:59 PM

Stick with the 3.4's. its the biggest you can go without machining the case (which you will have to do with the 3.5).

I am running 3.4 Mahle Yellowbird pistons and cylinders in mine. More expensive, but can't beat the quality.

as for low end driveability, make sure you swap out the cams. you will need a special grind since your going EFI. Talk to Steven Kaspar at IA as he is the guru when it comes to EFI

88-diamondblue · 01-30-2008, 08:36 PM

I put in QSC's 3.4/JE combo. Bought from Supertec. If you want to go to 3.5's Charles at www.lnengineering.com has slip fit 3.5 cylinders. I don't think they are listed on the web site yet but are available. Fantastic quality especially for a turbo application due to the large number of cooling fins. You would need to do a twin plug with that size of piston. Charles posts here at PP as CNavarro. Great project to do.

Barracuda · 01-31-2008, 02:19 AM

Yeah, I actually notices the 3.5 Nickies listed right here at the Pelican store as a "slip fit" and honestly...I thought it was a typo

Let's say I was to go the Nickies route to 3.5 versus 3.4...
What kind of extra power do you think is there?

cnavarro · 01-31-2008, 05:41 AM

I'll be devil's advocate - you could always take your stock cylinders too and strip them, bore, and replate to 98. Sure as safe a bet as going with a set of new mahle 98s, just with JE's of course.

And yes, I do have slip-fit 100s. :-) Our material is just that damn good!

That's how I've also gotten away with slip fit 103s for the 3.6 and even machine in 105s (and have been even toying with doing something bigger).

Barracuda · 01-31-2008, 06:37 AM

Don't be the devils advocate Charles, I've read about your cylinders and they are wonderful....Spill the beans on the 3.4 to 3.5 difference, assume I'm getting the Nickies either way

I want this car to be very quick however It's unknown to me as to what type of HP gain this will achieve

Barracuda · 02-01-2008, 01:47 PM

Oh. come on, someone answer my last post

cnavarro · 02-01-2008, 01:58 PM

I didn't get a notification email! :-)

Well, more displacement is always a good thing! How much boost are you planning on putting though the engine - maybe a twin plug 3.5, 8.0:1, new head studs, with about a bar of boost will be a very healthy engine. Single plug, then maybe 7.5:1. If you want to run more boost, it might be better to go with the 98s, since the tops are a bit thicker, and there is more room to do a flame ring. It all boils down to what your long term goals are for the engine.