76.4 crank in 3.0 case

[nikke911]

Need some opinion from the Experts on this forum regarding my next motor. Bought a 997RS crank new which i plan to drop into a 3.0 SC block.So instead of the usual SS i´m going LS-bigblock! The piston/liner combo will most likely be 102mm LN liners and Wössner specially made pistons.The oilpump is also 997RS and heads will be CMW-billet twinplugged heads.The cranksnout needs to be shortened by 9mm,otherwise it drops right into the 3.0 case.The cams are still a mystery,but i would like to make this engine rev too..The rods are original 3.0SC rods with ARP rodbolts.The heads will get forged rockers with titanium retainers(FLM design,UK).On top of this whole mess i´m going to use PMO carbs in either 46 or 50mm.Exhaust needs to be custom made,but i´ll probably continue on my open Megaphones with RSR headers in 1 7/8inch.This will be a street engine with occasional racing abuse. Opinions..

[Raceboy]

If mostly street engine, I would definitely go with EFI+ITB setup, not carbs.

[VFR750]

Are you sure you want to keep the stock 3.0 rods? Big 102mm pistons and high (how high?) rpm might require stronger rods.

BTW, I'm not an expert. On my journey I read that 3.0 rods are good for mid-7000s with lighter J&E pistons verses the KS CIS pistons. Jumping from 95 to 102 seems to counter to this.

[nikke911]

Been considering Pauter or Carillo rods but some people trust the original 3.0 rods with stronger bolts.But if someone out there needs to get rid of a set of Pauters or Carillo i might be interrested..

[lvporschepilot]

A PMO EFI set up would be optimal for what you're doing. DC40 of DC43 ish cams would probably do the trick as well. This will be a great build. Are you shooting for a streetable 350bhp ish range?

[Raceboy]

I could offer complete EFI ITB kit that would include programmable VEMS ecu, ITB's, Pipercross filters, wiring harness, necessary sensor, already usable calibration (you can start driving right away) etc for a bit less than PMO asks for ITB's only.

[Edelweiss]

Good concept !

To be historically correct we have done several engines with the Mahle 100 mm bore and the 74,4 mm crank.

It is a classic 3,5 L combination and can be used here in Europe for groupe 5 racing since Porsche Motorsport was using it together with some well known teams in the late 70s early 80s.

It makes a wonderful elastic and drivable engine pulling approx 360 HP with a RSR butterfly / Bosch mfi pump setup.

We shift these engines between 7500 and 8500 rpm.

If you use the 76,4 mm crank it will even be more elastic and you can reduce the dome hight which will promote the flow in TDC.

I have developed several cams for this engines with modern and very effective lobes, by the way.

We are currently building an engine where we use our 82 mm longstroke crank also together with our 100 mm pistons ( 20 mm pin ) and 130 mm conrods, based on the same housing.

So if you're going with the 76,4 mm crank there are 53 mm bearings and you should use some Pankl TI conrod out of the GT 3 range which are available in 132 mm length.

On this way you reduce the lateral forces but even more important there are positive effects on the gas exchange process. The piston will stay longer in TDC and this will make some more power and torque by the effects often discussed and explained.

Best reg.

Dirk

[nikke911]

Thank you guys for your input!I´m aiming at steetable 360-380 hp on this one since my current 3.2 SS puts out nearly 300 hp and is much milder than this will be(read much less expensive..).Dirk,i´ve been looking at the Pankl rods aswell but (correct me if i´m wrong) these need special bearings also which are VERY expensive.

[Edelweiss]

Hi,

no need for special bearings !

If you want GT3 cranks 76,4 / 80,4 / 82 /84 mm, conrods, bearings and suitable air cooled pistons for your build just let me know.

Most of it is available ex stock at Edelweiss Motorsport.

Best reg.

Dirk

https://de-de.facebook.com/edelweissmotorsport

[JakobM]

Originally Posted by Raceboy

I could offer complete EFI ITB kit that would include programmable VEMS ecu, ITB's, Pipercross filters, wiring harness, necessary sensor, already usable calibration (you can start driving right away) etc for a bit less than PMO asks for ITB's only.

VEMS is great!
What ITB's are you using?

[JV911SYDNEY]

Nice build!

Rothsport ITBs, pauter/carillo rods and a custom grind Elgin cams would be on my shopping list

[Raceboy]

Originally Posted by JakobM

VEMS is great!
What ITB's are you using?

I have used GSXR1000 and Hayabusa ITB's.

[JakobM]

Originally Posted by Raceboy

I have used GSXR1000 and Hayabusa ITB's.

That is interesting, so you make both your own linkage and cyl-to-Itb manifolds?

[Raceboy]

Yes.

[totle]

Just received my order of ITB kit from Raceboy.

Great parts, great workmanship :-)

VEMS next :-)

[Raceboy]

Thanks Trond! Not to hijack the thread, but when installing, please test fit the intake flanges regarding port matching!