Someone running 3.0 (SC) with MFI ?

[RS-GT]

Hi,
My plans are a 3.0 SC motor with JE pistons and MFI (in a narrow 72) ; Any comments on performance, concerns, comments ??

Which cams/MFI space cams are you using? and give me more details about yours !!

Thanks,
JD

[Jeff Higgins]

This should keep you busy for awhile. It's sure kept me busy...

Another Successful Pelican Engine Build - My 3.0 Liter MFI Project

MFI Pump - Open Heart Surgery

Expensive Lesson in MFI Tuning

Putting My 3.0 MFI Motor Back Together

[RS-GT]

THANKS !! I will need to review my search procedure !!

JD

[911st]

I am not an expert but a copy of the factorys 3.0RS motor is a solid proven combination.

S cams, S injector stacks, w RS space cam set up by Guss and Pacific Fuel Injection in SF.

Good luck.

[Jeff Higgins]

Yes, a 3.0 RSR motor (I don't think there was a 3.0 RS motor) is a solid, proven combination. As a race motor. One would be very difficult to live with as a street motor, however. And a bit expensive to put together.

A 3.0 RSR motor has many parts that fall into the "unobtanium" class. Not that they are truly unobtainable, but their scarcity is reflected in their price. High butterfly throttle bodies (or slide valve) lead the list. Eurometrix currently lists the high butterflies at over $10k a set. Yes, that is ten thousand dollars.

A true 3.0 RSR motor has very large ports and matching throttle bodies (I believe 44mm). S throttle bodies are 36mm. S throttle bodies can be opened up, along with S stacks. I believe Supertec can do this. It ain't cheap... Early, large port SC heads can be ported to match (for that matter, the later small ports heads can as well). It's probably not what you want, though. This is high rpm racing stuff, sacrificing low and mid range power. Not what you want in a street motor.

The cams used in RSR motors are not early S cams. They (RSR Sprint cams) are readily available, but are designed for very high rpm race motors. Entirely unsuitable for a street car that sees occasional track use. Think 8,000 rpm's...

RSR pumps, or even their space cams, are very much towards the "unobtainium" end of the spectrum. The sealed "red top" pumps are pretty much all spoken for, and their owners do not readily part with them.

In light of all of this, I essentially built that "3.0 RS" motor. 36mm S thottle bodies and stacks, small port SC heads ported to match, a set of custom Dougherty cams, JE 10.5:1 pistons, and Electromotive twin plug. I love it as a street/track motor. I had some hicups along the way towards sorting it out (details are in the threads linked above), but I'm extremely pleased at this point. I ran it yesterday at a PCA track day (and last Wednesday at an Alfa club day) at Pacific Raceways, and it ran like a top all day long. I had no trouble pulling 964's, 993's, and 996's down our long front straight or out of any of the corners. 245 hp in a sub 2200 pound car is a lot of fun...

[javadog]

Originally Posted by Jeff Higgins

Yes, a 3.0 RSR motor (I don't think there was a 3.0 RS motor) is a solid, proven combination. As a race motor. One would be very difficult to live with as a street motor, however. And a bit expensive to put together.

Actually, Porsche built a 3.0RS motor for a series of street cars in 1974. 230 DIN hp. The later 1984 SC/RS was even better, as it made 255-270 DIN hp. depending upon the exhaust that was fitted.

I've seen a few road tests of an RSR (ususally the 2.8) that indicated they pulled well from low revs, in spite of their cam timing. Maybe the low curb weight helps...

JR

[911st]

Again a 3.0 RS motor (not a RSR). This is just a 2.7 spec motor on a 3.0 case w readjustment for the displacement is my understanding.

It used the proven and has a well matched (and existing) space cam.

Add a sport muffler and a bit of compression as they were 8.5/1 and you should have a good 250hp motor that has no drivability issues.

You could open up the stacks from 36mm to 38 for some more top end.

[Jeff Higgins]

Oops - you guys are right. I completely discounted that one, as only a handfull were ever made, and most were turned into race cars. I think they had a lot of trouble with them, having finally pushed the limits of the spigot holes in the mag case.

[javadog]

Actually, they used an aluminum case. Porsche figured out during the 1973 racing season that the magnesium cases used on the RSR were prone to problems, as they went from 2.8 liters to 3 liters. Thus, they went back to an aluminum case for the RS 3.0 and RSR 3.0.

JR

[Henry Schmidt]

We build them all the time. This one made 310 DIN hp @ 7200 and had a flat torque from 3600-5800.

[911st]

Henry,

Oh that is sexy!

Looks just like a 2.8 TP/MFI I once owned.

[RS-GT]

I'm starting collecting parts tp built a nice 3.0 (I will call you soon Henry to discuss about it !!)

The original "S" MFI stuff is quite difficult to find so what is the best package to strat with. I already have a 2.4T system but someone is offering me a 2.0E package : pump 004 and early throttle body in aluminium (or magnesium?)

Which one is better ; pump components (brg,...) and possibilities to open the ports ?

Thanks
JD

[911st]

If you do not mind comments from the gallery.

Depends on your goals.

The 2.7RS was known as the best running of the MFI motors. There are factory specs for the same basic motor but as a 3.0RS.

If you want a nice running street / sport motor. Use the 2.4 pump and have it converted to 3.0 RS specs. Run S cams or modified S cams with it and have the injector stacks opened up to S specs 36mm. You might be able to go a little past this but if you do let the pump builder know so he can compensate. Also let him know you are going to run a sport muffler.

MFI is sensitive to variations and it is going to deliver a specific among of fuel so if you have changed something, it may create a problem.

This is a proven combination and a great driver.

Want a bit more and really crisp motor, bump the compression and run twin plug.

Out side of that you are forging new ground and may or may not end up with a motor that is well behaved.

[Jeff Higgins]

I used all 2.4 T components on my 3.0. The plastic stacks are easily opened up to 36 mm S configuration, as are the throttle bodies. The pump (015) is easily reworked to run on the 3.0.

[jm993rs]

Hi !!! I have the same idea

Is Ok the pump 014 ???

Is possible anybody please explain the upgrade need make in the pump ? Any DIY ? Any vídeos ? Thanks !!!

I'm subscribed to this thread

[Reiver]

Damn Henry you're killin me....

[RarlyL8]

I've got a complete system set up for a 2.8L high output engine if anyone is interested. All fresh, the project died and I ended up with the MFI system.