How big can I make my 3.3 turbo motor?

[drmatera]

I am in the homework stage (pre-build) of my summer project which is a full rebuild and upgrade of my '86 930 3.3 motor.

This is what I have so far in the parts dept.
3.6 turbo crank
Stock length Carrillo rods
GT2 EVO cams
Stock 3.3 heads will be twin plugged and ported by Extreme cylinder heads
ARP head studs
GT2 oil pump

since I will most likely be replacing the P&C's with LN Engineering/J&E my question is how big can I make this engine while keeping reliability? I am shooting for 650-700hp and is a street car that sees alittle drag racing and even less road racing. I am currently looking at 100mm P&C's

Thanks for any insight you can give me.

[Flat6pac]

If youre looking at open market head studs I would look to the Supertec head studs because the fine thread on the torque adjusting end is super control of the torque.
Would be my preference.
Bruce

[nocarrier]

I would imagine that going with a large diameter cylinder ends up leaving less and less sealing surface between the heads and cylinders.

Also, If you decide to add flame rings, I would imagine the material around the grove may become weaker as well with the reduced diameter of the sealing area.

I wonder what the "safe" limit is.

[Ken911]

98mm is the largest you can go without machining the spigot holes. 100 mm will require the holes opened up or else your cylinders will be too thin. I went went 98mm. which is an easy one to do since almost all of them are made from 3.2 cores. I know you plan on running high levels of boost. So you will need to make sure they are strong. Also when you start getting up around 600 to 700 hp the case will move and so you should get it shuffle pinned. other wise it will be back apart pretty quick for new bearings. Ok since your the MS expert here what do i need in the way of temp sensors? Where do they get installed? And what should i do for injectors? I plan on keeping it a 3.4 with 7.5 to 1 twin plugged but want to run both e-85 and 93 octane. Gt2 evo cams, my heads are already ported. run my k27 hfs until i can aford to move up to a garret. I'll stay with stock rods though. still undecided about shuffle pinning the case.

[Ken911]

Oh one more thing I learned yesterday. I saved a bunch of money buying Toyota coil on plugs instead of the VW ones....I thought. but when it came time to buy the connectors not so much. they were hard to find. When every one sold the connectors for german cars. So it was 400.00 for 12 coil on plugs plus connectors. 300 for the cop's.

[Henry Schmidt]

We just finished building a 3.3 upgraded to 3.45. GT3 crank, R&R rods and 98mm Mahle pistons and cylinders.
If the question is "what's the max size?" I would talk to Charels @ LN. I think he makes a 101mm cylinder for the 3.2/3.3 case.

[drmatera]

Ken, I've got the sensors you need for IAT and CLT. I put my CLT sensor on the banjo bolt that feeds the turbo oil, the IAT is in the intercooler tubing just before the TB. As for injectors, you might as well go with 60's if you plan on playing around with E85 because once you do you will never let pump fuel near the car.

[drmatera]

Thanks for all the replys. I think the 101mm's are the path i'm taking. Now I have to consider compression ratio..

[totle]

This is going to be interesting to follow:-)
I have kind of the same setup, but not that high hp. 505/635 rwhp/Nm at 1.1 bar and 98 eur octane

Keep us updated :-)

[TurboKraft]

98mm with a 3.6L crank = 3.45L displacement, like we built for Tom's engine (2010: EFI Hot Rod Odyssey). Case machining not required.

100mm slip-fit also available -- we're building a few of these right now, makes 930 a 3.6L without case machining.

If you're open to machining the case (dowel pin and boat tail main webbing at same time?) then 100mm and 102mm bores are options.

The skirt is thinner for the 100mm slip-fit and the 102mm machine-in, but the LN Engineering cylinders are really, really strong -- we trust them completely. It's what we use in nearly all our builds and what we sell.

[drmatera]

Chris, Thanks for chiming in on this. I will be calling you for the P&C's when the time comes. I like the sound of 3.6L