930 Twin Turbo 3.4 Project...commencing...

[YTNUKLR]

Thought you guys would be interested in my latest project, a 3.4 Turbo engine for an '89 930 Cab. Going to be EFI, and actually will be running TWO turbos, though I'm just taking care of the longblock assembly for now.

Got started this evening cleaning up the case and installing the new (very sweet) Supertec head studs! Good tip : Glad brand "Press 'n' Seal" is a great product to seal up the motor from contaminants when you're not working on it. Basically like saran wrap but, it doesn't automatically stick to itself and end up wasting a whole roll.

The plan...
-98mm re-bored Mahles + JE pistons, about 7.5:1 compression
-GT2 Evo Cams
-Twin-plugged Carrera 3.2 heads, 40/38 ports
-of course, ARP bolts
-also got some trick Iwis 993 "Race" chains that appear a little beefier than the standard items

I will be updating this thread with progress pics throughout the week...THIS is what your case should look like after a lot of TLC! Gotta hit the sack so I can wake up and get crackin' on putting this monster together!

Cheers
Scott

[YTNUKLR]

Got the case sealed up today, and the pistons and cylinders on

sealed up the case using a thin layer of threebond 1104, loctite 574 on main saddles, threebond 1211 on the number 8 bearing..along with some DOW 55 o-ring lubricant, very good stuff to lubricate o-rings and prevent them from tearing.

Calculated compression as follows..let me know what you guys think:
-head cc 92.7mL (twin-plugging them increases the volume from ~90mL)
-piston dome cc ~16.5mL
-deck height came out around .85mm, which is a little tight, but should limit detonation even better. I am taking a risk on the fact that the Evo cams will clear the pistons amply..we'll see
-actual bore is 97.99mm

C/R came out just under 7.8:1 by my calculation





The cylinders are number 4-5-6 on the left bank...they did not correspond to engine position when I numbered them





Finished up here for the night:


PS. yes I was wearing sandals (third photo down)!

Cheers,
Scott

[hobieboy]

Scott,
Sounds like an exciting project! Please do keep us posted.
What ECU/EFI scheme will you be using? And what turbo, exhaust, ... ?

[Lukesportsman]

I'm watching with great interest. This is quite similar to the engine I'm just begining. I'm looking at a very similar longblock with same cams planned. I'm going to run 993TT HE's. I've got 3 different turbos in the garage...still trying to finalize that. Looking at dual plugs and MSII to fire and fuel. Probably 3.2 intake, what are you thinking?

I've thought of going to 8:1 with the larger cam and to lean more to street than track in my case.

Please keep us posted of your progress.

[YTNUKLR]

This motor will definitely have a 3.2 intake, I'm not sure what ECU he is going to use, but I think Motronic from a 3.2, reprogrammed by Steve Wong. It will have a 993 distributor to fire the plugs.

8.5:1 is really the safe limit with twin plugs, I imagine EFI + the Evo cams would allow this combo to work quite well. 8:1 is good, this motor is just a little lower than that but if he wants more power, turn up the boooooost!

I would imagine he'll go with GHL headers and K16s, though those choices are not finalized yet either

I'll be posting more progress pics, the next step is cam timing ~2.5mm and a piston/valve clearance check

Cheers
Scott

[Lukesportsman]

K16 is the obvious choice and I have stock K16 as one choice. I'm still contemplating the advantage of bushing GT's. I'm just a little concerned about BB GT's with no water and without oil restricters. I know this is up for debate and being mostly street and DE it may be a mute point. Still tossing ideas in my head.

I just sent up a GT exh housing to Ben to have Vband flanges made just so they're ready. I don't think there is anyway that I can make it switchable between the KKK's and GT's though that would be ideal to determine best for application. I don't think I'll outrun the KKK's with the lesser displacement, but wondering if there isn't a better/more modern choice....hmmm.

[YTNUKLR]

Luke, I've certainly contemplated a turbo motor for my own 911, and I've read a lot about turbo technology, etc., and have a basic idea of parts involved for a twin turbo motor of this type.

Yes, the K16 is an obvious, proven choice for a motor like this. The goal is 500 streetable hp, I think we'll easily accomplish that. I need to look into various other options for twins. I know when I was looking at compressor maps for a single-turbo motor, it seemed like the BB GT's would work well, like the 32, 35, etc. The KKKs are proven and "easy" but again they are 10+ year old technology, and I imagine there are better alternatives available. Not related to Porsches, but I've seen many, many other turbo cars running Garretts with no issues to speak of. Juan Ruiz's car, also ran Garretts, and I don't think I ever read of an issue with them.

For now, it's just longblock assembly while the chassis is finished. Maybe not my first choice in automobiles, but this one will certainly be a show-stopper: it's being mod'd to clone the look of a '94 964 Speedster, with a wing of course. I'll keep you posted on the rest of the motor progress

Best of luck,
Scott

[935TURBO]

Hi Scott....I'm interested in your project to....of course....

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And at present, I didn't stop my choice for EFI/Ecu......because anyway, I'll have to tune it by myself....there's no dealers/installators for that kind of system here in my country....