Driftomagnifico

Do you have more info on that engine. That is a ****load of RnD to make that 8v head support that sort of power N/A.

evil 944t

Not really a ****load, just the right amount. Everything inside of it is custom. There are no "off the shelf" parts. The cam is custom too.

That turbo head flows about 247/192cfm@ 550 lift. The n/a heads are flowing a bit more due to the larger exhaust valves. The 16v heads are off the charts!

Luke

315whp (~400hp) out of a 2.5liter 8valve?

Post some charts.

333pg333

Hey Dave leave my numbers out of this... So if the stock turbo head flows approx 188, a modded one approx 250, what does the corresponding 16v's flow? Do the 16v's suffer tq loss at any point compared to a decent 8v? If so on a shorter, twisty track would there be any advantage of the 16v over the 8v?
Also to digress guys, this is just a theoretical discussion. No real need for criticism. For example Fishey you seem to be alluding to Nitrous I assume? So say so, don't just laugh at us from the sidelines. I value most of the input I get from these discussions and from people that know more than I do. That's why the kid started this thread, and a good one it can be.
It would seem that we all agree that the VE can be improved markedly on our cars. The days of just putting on a bigger turbo to get a whopping 380hp* are over. As Travis, Dave, Drifto and others are saying it's time we tried to catch up to what is just standard in other makes. It's highly unlikely that we'll see 1000hp from one of our cars so this is all just a friendly theoretical. However if they got 1500hp out of 1.5L F1 cars all those years ago then surely we can get a safe 700hp out of 3.0L ? Seems fair to me.
*figure plucked out of air.

Driftomagnifico

Off the charts by what amount. Considering they were for a 2.5L engine they'd have to be pretty high.

Ported K20 / SR20VE cylinder heads flow 340+ on stock valves at 0.500" - 0.550" at 28in. H2O. Those are supporting 2.0L engines. To give you perspective I've seen a K20 engine put down 314whp on pump gas naturally aspirated. The Nissan engines don't make nearly as much mainly because they have a much smaller market support.

Driftomagnifico

Built correctly with some work I don't see a problem in making a 2.5L make 600 - 700whp with a full T4 framed turbo. However economics is not on your side of the fence as Porsche parts carry such high market value and like I said before, getting the engine to rev out isn't very cost effective since you don't have any OEM-similar parts to upgrade to.

333pg333

Ok any guesses what Corleone will make from his car with these mods?

Here is some short spec:
3 liters Darton sleeved
JE coated pistons
Milledge cam with solid lifter´s and titanium retainers
All bearings coated
SFR 4-1 exhaust manifold
Tial 46 with its own 2½" exhaustall way back
Head with Ferrea 48 mm intake valves and 42 mm sodium exhaust valves with beryllium seats
14.5 mm head studs with modified block, torqued with 175 nm
Special made intake with shorter runners and "real" velocity stacks, 6 liters volume. 65 mm trottle house
1600 cc injectors
Special made IC with flowed test tanks, 4½" x 24" x 16"
Garret GTBB
Link G2
MSD DIS 4 Race

Looks like he has most bases covered here. It will be interesting what he gets, provided his car survives? Amongst other things his break in procedure reads:
'Drive it like you stole it'.

evil 944t

Drifto, since not many here have flowed these 968 heads, I can tell you that in stock form, they 450lift, they flow as much as that ported K20! Thats Stock!! I of course, flowed the head to 550lift and saw even bigger gains. A ported head and bigger valves really moves air.

Patrick, You would need to change the gearing in your car to keep these monster heads spooled up. If you keep it stock but change the cams, you can have yourself a nice track motor. The top end will be enough to make you forget you have no power under 4k rpm.

RKD in OKC

Not to change the direction of the topic but....

I understood from when I was younger that one of the big things about the Porsche 3.0 Liter six cylinder was that the piston mass was optimal for power output vs displacement. Now since even Porsche is running much larger piston sizes I would assume that max ouput is at least cheaper by increasing displacement. This is similar to Porsche stating for years that air cooling was the most efficent cooling, but later moved to water cooling because they "could not make any more power with air cooling."

Luke

Oh, they made more power... it just isn't reliable power. When the heat soak really takes over the #'s drop on the air cooled engines. That's about when they started using the watercooled heads like the 956 IIRC.

All piston combustion engines are pretty much 30% power and 70%heat. So, if you make more power, you'll obviously be making heat as well. They just got to a point where the air/oil cooling couldn't pull the heat away from the cylinder head fast enough.

Fishey

Emissions killed the Aircooled car and first person who can tell me why gets a cookie!

SamGrant951

Im guessing they were way more expensive to build (to meet standards) than a watercooled motor?

Fishey

They are more expensive to build without a doubt (new carrera engine is garbage as is the gearbox) anywho. It has to do with emissions

Driftomagnifico

As it should since it is supporting an engine with 25% - 50% more displacement.

Driftomagnifico

Without turbo specs you really can't narrow it down.

Why is he running a 65mm throttle body? That is way too small.