mudbuddha

I am running a 3L 8V. The snail on this motor is a little on the small side, I guess by today's standard, for this application, however; spool up and response is great which works out for me for street use.

333pg333

Mine was on a 2.5L 8v with a bigger cam and GT3076.

Dubai944

Yes I don't think that's the case. This was two days of careful tuning looking at every part of the map and playing with different timing, the two exhaust and the variocam, not just a quick session for full throttle results. The hp and torque results were repeatable over and over again.

The only other cars that run the C2 a lot are the 350Z crowd. Those guys get 11-12psi max, then they break their cog belts, but they don't make any more power than I am. I did read one guy got 14psi on a modified 350z and made 400whp. But that's not comparing apples to apples so a bit irrelevant, more efficent engines make less boost anyway. I think a combo of the 968 head and the cams means my engine is flowing reasonably well. Would love to see what it would make with 20psi.

Here are some pictues of the engine. Like I said it's not very pretty. It's not even clean...lol.

Thom

Anyone got a map of this Procharger C2 compressor?

Dubai, did you install the intercooler upside down so that inlet/outlet are the same as on a 944T?

Dubai944

Procharger don't publish compressor maps which is very annoying. All they will tell you in the specs is that the max flow is 1100CFM, and it is capable of a maximum of 24psi and 725hp. How they arrive at that I don't know.

Upside down intercooler... no idea. It only went in one way I assume the same way as the Turbo with the angled outlet on the passenger side (on a LHD car)?

333pg333

I think the upside is that you have a very usable motor that shouldn't stress components nearly as much as some of our higher boosted turbo motors. Assuming peak cylinder pressure is also way down on ours, you should be holding headgaskets better than some of us too?

Thom

It'd be interesting to know how much it flows at 10psi, as if it flows a lot more than the K26 compressor with which the standard IC was designed to work at this same pressure of 10psi, the IC may get heat soaked quite quickly.

The inlet of the stock IC is angled to increase the speed of air as it enters the IC. If air flows through the other way around, the IC may not be as efficient as it is supposed to.

Dubai944

Good point and I have to admit I had never considered that I am running it backwards to how it was designed and that might have a negative effect. Will have to take a close look at the intercooler and intake setup in general.

Van

the intercooler only mounts one way, but on the turbo, the left side of your pic is the inlet (from the turbo) and the right side goes to the throttle body.

Dubai944

Yes I get that. It just never occured to me before Thom mentioned it that I am using it backwards to the way the turbos use it. Now I am really wondering if this would make much difference!

Thom

The first 968 TRS underwent modifications in the US, one being running the standard intercooler the way you do, the other way around.



When looking at this picture it's tempting to think it was done this way mostly to clean up the layout for the IC ducts because of the custom intake manifold, at worst without necessarily paying attention to this detail or at best thinking it wouldn't make much of a difference on this particular engine set up.

fast951

Good numbers. I noticed the BOV venting to atmosphere. Does the SC have a recirculating valve built-in?

Do you have a way to bypass the SC when under vacuum? Usually, there is a internal valve or a external recirculating BOV (same as factory 951 BOV but is connected in reverse) to direct air to the intake around/bypassing the SC till you get on boost. On boost, the BOV closes and air goes through the SC.

Dubai944

Hi John,

There is a recirculating BOV, black plastic one next to the intake manifold behind the supercharger. A bit hard to see in the picture but you can see the blue vacumn hose running to it. That also vents to atmosphere as there is no MAF. Is that what you mean?

The big silver valve on the out pipe from the supercharger is a big ball and spring valve from 928 motorsport with a screw adjustment, to allow a crude form of boost limit control. I installed it originally thinking that by gearing the supercharger to run at its maximum to make boost early it might make too much at the top end. Obviously I haven't had that problem! At the moment it is screwed up tight and theoretically shouldn't open with less than 30psi in the pipe. That's one thing I need to check and blank off because it may be still leaking a little and contributing to the loss of boost over 10psi.

fast951

Ok, now I see the black BOV. Shouldn't this BOV be connected between pipe in front of SC and pipe after SC but before TB?

In a SC application, for efficiency, under vacuum (Idle, Cruise, between shifts) a SC bypass mechanism should be in place to allow air to enter the intake without going through the SC. Under load (no or low vacuum), the bypass closes, forcing the air to go through the SC.

Think of the BOV system on a SC, the same as the 951 BOV system, with the difference in the orientation of the valve itself.

I wonder how much of a drop in IAT temps in the manifold you'll see by adding a bypass system.

Dubai944

As I understand it the design on the original SFR kit was that the BOV is just there to stop air trying to force it's way back through the compressor when the throttle is shut. The outlet to the valve is immediately after the compressor and originally went back into the intake pipe before the compressor so that it didn't screw up the MAF metering by dumping air to atmosphere. All I have done since is block off the intake pipe side and let it dump to atmosphere.

I need to study out the bypass setup more closely by the sounds of it.