Winter Project -- 3.8L(4.0L?) Track engine build
 

My 911 RSR came with a 3.8 in rubbermaid boxes several years ago.

I put a 3.6L street engine in with the go fast parts (ITBs, headers, exhaust, Motec ECu) that came with the race car.

It was a good starter engine, and I won't say I'm that competent a driver, but I'm ready for an upgrade. COTA is the main track this car sees -- and topping out at 125 in the straights -- well I could use a little more HP.

I could hand this off to an engine builder -- but that would take a lot of enjoyment of the project out of it for me. I have access to a knowledgable 911 mechanic and I did the top end on the 3.6L myself. She's held together for 2 seasons of tracking as I've learned to drive the beast.

So I won't call myself qualified or competent engine assembler, but if I get the right parts -- I think I have a good chance of getting it all working.

This is where I'm asking the experts here for some guidance.....

This will be a budget build -- well at least a reasonable budget. Do the right things, but make reasonable decisions on components.
The case is already set for 3.8L jugs.

Already have Carrillo rods and the heads (from a 93) are good to go save valve springs (stole those for the 3.6), and will want racing springs to gain some RPMs.

I'm looking to rebuild the 3.8 might even push it to a 4.0. (I don't have a race class I am trying to fit in - and if I did -- the 3.8 and 4.0 fall into the same category.)
My concern with the 4.0 is that why jugs would have a taper as the case is machined for a 3.8

Plan to go with LN Nickies (they have drop ins for both for my block)

My goal is to have a ~8000 rpm redline.
Today she turns at 7200 with the 3.6K using 953 valve springs without floating.

Looking for recommendations on what main and rod bearings to use.
Head Studs, rod bolts, and valve springs.

I'm looking for strong and reliable -- I won't tune the piss out of it, but
she needs to be able to handle an occasional heal/toe over rev -- being realistic
with my driving skills.

thank you for you help and guidance,

thanks,

Mike

Stroke
 

Dear Mike,

if I would be in your shoes I would stroke it up to 80,4 mm.

On this way you have 3942 ccm and it is a very elastic engine which still revs sky high on demand.

Automatically you gain static compression so it opens the door for a modern cam set up.

We did this before and see 100 hp / l as easy as reliable.

The Crank and oil pump as well as the cam we have available ex stock - the existing 102 mm cylinders we hone at Mahle. Pistons need to be 2 mm shorter if you keep the conrods and we do them from Mahle 124.

This is from our experience the best package in HP / torque / investment ratio keeping your engine housing as it is.

Because of the crispy cgaracteristic it is unbeatable fast on the track.

Best reg.

Dirk

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