Pelican Parts Forums - Old school with a twist

Pelican Parts Forums (http://forums.pelicanparts.com/)

- 911 Engine Rebuilding Forum (http://forums.pelicanparts.com/911-engine-rebuilding-forum/)

- - Old school with a twist (http://forums.pelicanparts.com/911-engine-rebuilding-forum/434823-old-school-twist.html)

Old school with a twist

Supertec has decided to build an "old school format with a modern twist". The base platform is a 2.5 liter, MFI, twin plug engine. The twist is this engine uses GT3 Gen 2 titanium rods and a new peanut shaped combustion chamber.
Why, we wanted to build an 8500 RPM high compression engine that would run on pump gas.
Twin plugging helps with low octane ratings but the new innovation is to replace the standard Porsche hemmi head with a more modern peanut shape chamber. This allows us to run a relatively flat top piston to generate high compression. This one will make a static compression of 10.25 to 1.
We start:
68 aluminum case
shuffle pins
piston squirters
boat tailed (I know, boating makes no measurable difference, but this case was boat tailed when I got it)
oil bypass modification
oil mod for cross drilled crank
Dry film Moly coating on main bearings
Distributor mount modified for late shaft
Mounts welded for MFI pump
Oil pump
Supertec flow modified Carrera pump
Crank 2.2 counter weighted
Cross drilled
Knife edged
Journals ground to 53 mm RSR with .100" fillets for strength (GT3 bearings, dry film moly coating)
GT3 Gen 2 titanium connecting rods (130mm center to center)
911 SC distributor gear (counter clockwise rotating)
Ion plasma surface hardened
Pistons and cylinders: Mahle 8.5:1, 90 mm RS
Supertec head studs
Heads:
2.4 heads with MFI injector ports
Peanut chamber (51cc)
Big valves 47 mm intake and 41 mm exhaust
38 mm Venti Port intake
37mm exhaust port
Heads have been shaved .040" and a .040" dimension shim added. This a shim placed between the head and cam tower to return a shaved head to proper thickness.
Supertec valve springs (90lb seat pressure and 220lb @ .500" lift)
Aasco titanium valve spring retainers

http://forums.pelicanparts.com/uploa...1223607617.jpg
http://forums.pelicanparts.com/uploa...1223607642.jpg
http://forums.pelicanparts.com/uploa...1223607664.jpg
http://forums.pelicanparts.com/uploa...1223607715.jpg
http://forums.pelicanparts.com/uploa...1223607734.jpg
http://forums.pelicanparts.com/uploa...1223607750.jpg
http://forums.pelicanparts.com/uploa...1223607775.jpg
http://forums.pelicanparts.com/uploa...1223607811.jpg
http://forums.pelicanparts.com/uploa...1223607839.jpg
http://forums.pelicanparts.com/uploa...1223607859.jpg

Sweet hell that thing is going to be music to your ears :D

Henry, might I ask who you have complete your ion plasma hardening process? I've been researching some places to do this task on other various engine builds here myself and just like to hear other shops personal experience or choices.

Ion plasma hardening? Titanium?...

Does it have Warp Drive or a Flux Capacitor?;)

Henry,

Impressive work, as always.
I was looking for a flywheel pulley with the degree graduations, do you sell those?

Aurel

Quote:

Originally Posted by Aurel (Post 4230179)

Henry,

Impressive work, as always.
I was looking for a flywheel pulley with the degree graduations, do you sell those?

Aurel

As always, please check with Pelican Parts (our gracious host) to see if they offer a product you can use.

Yes, we sell the power pulley in two sizes. 101mm and 107. The key to the power pulley is to synchronize fan speed and engine rpm to optimize fan efficiency.

Reducing fan ratio/speed at high engine RPMs lowers parasitic loss, operating harmonic vibrations (noise) and improves cooling.

A side note: The last time I made this statement , John unilaterally moved my post to a thread about fans speed. I hope he will avoid that transgression this time.

I recall a month or so back you showed some welded chamber heads from a 2.7. These had a similar squish profile. Did your shop weld this set of heads? I like the design. Interesting to see how it performs.

Do you offer the cam tower dimension shims in other sizes? This is a great alternative to shaving cam chain housings and the resulting chain slack.

looks great! do you think to make a more budget version using a 7r mag case, standard 2.0 rods and stock valve sizes would work? i really like that the heads allow the use of typical rs low compression pistons.

What am I seeing welded on the case?

i think its mounting brackets for the mfi pump

Did anyone make a projected Hp guess ?? maybe we should start ??

I'll guess first- 285 hp?

Is it the lack of knock sensing or the air cooling that prevents you from going higher on the compression? A GT3 would have a over a point higher c/r on pump gas, and it has larger combustion chambers and single plug, but I'm guessing 10.3 is already pushing it for air cooled.

Very nice- that will sing...

Quote:

Originally Posted by jpnovak (Post 4230267)

The heads are the same heads I posted a few months ago. We have twin plugged them and added a set of big valves and Venti Port.
They were not made by our shop. They were found in a core trade in engine.
We put them in Solid Works and had them flow tested for preliminary research for possible production.

The spacers for these heads are .040" and made of aluminum. We are producing a batch of steel spacers that measure .060" for for in our retail inventory.

Quote:

Originally Posted by gestalt1 (Post 4230719)

I can't see how the use of these heads could ever be concidered a "budget version".

Quote:

Originally Posted by mb911 (Post 4231194)

What am I seeing welded on the case?

The case has two seperate welded changes.
First is a mount for a Bosch MFI primary pump.
The other welded item is a distributor mount. This convertion allow with boring the case allows us to run a 911 SC style distributor.

Quote:

Originally Posted by petevb (Post 4232063)

Our goal in this project is two fold.
First, twisting this gem up to 8500 on street gas.
Second, product a usable power band of 4500-8000 rpm.
This is a monumental task and with these goals I would think that 285 is very optimistic.
I would think 260 might be a little more realistic.

Henry - great looking machine..... are the case mods (distributor and MFI) similar to those in Armando's gallery ?

Regards
John

Reporting a little more progress.

You might note the 906 cooling tin and the installation of later style aluminum chain boxes. The case was modified to accommodate this up date. It is difficult to see, but there are .040" dimensioning shims installed between the heads and cam tower to compensate for milling .040" off the heads. The selant used for this was ThreeBond 1104.
The chain boxes need no trimming and the chains will dimension without any modifications. using stock tensioner wheels. We will be installing turbo chain tensioners w/chain savers and our custom bushed tensioner arms. The DC 90 cams should be here tomorrow.
http://forums.pelicanparts.com/uploa...1224029074.jpg
http://forums.pelicanparts.com/uploa...1224029084.jpg
http://forums.pelicanparts.com/uploa...1224029339.jpg
http://forums.pelicanparts.com/uploa...1224029105.jpg

http://forums.pelicanparts.com/uploa...1224029872.jpg