2.2S cams and MFI on '80 3.0??

BK911 · BK911's Garage

I was parting out a 2.2S engine but still have a lot of parts that didnt sell, so I am thinking of using them in a 73.5T 3.0 Coupe DE car.

If I bought a new set of P/Cs for an '80 3.0, could I use the 2.2S cams and MFI? What if I went 3.2? Is the 3.0 a 3 or 4 bearing cam tower? If 4, will the 3 bearing bolt on from the 2.2S?

The car is mainly used for DEs and mountain runs.

Thanks!

jpnovak · 05-10-2010, 10:46 AM

Brian, you will need to use the early 3-bearing camtower with the early S cams. They will have a 47mm journal compared to the 49mm journal of the later cam tower. Functionally the tower will bolt to the 3.0 heads with no problems. You would need the early cam tower to clear the MFI pump drive unless you want to pop out the rear cam seal on the DS tower and install the appropriate parts to run MFI.

Yes, you would need new pistons to clear the cams.

Halm · 05-10-2010, 12:39 PM

And then get the MFI pump rebuilt for 3.0 displacement, get the stacks bored out, and valve relief machined into the pistons.

Rick Cabell over on the Early S board has a real deal factory 3.0 MFI motor. You might ping him for more advice.

911st · 02:37 PM

You can get your cams reground to S specs and a pump drive added if needed.

However, your MFI pump is going to be the issue. If it was a 2.4 you could use a 2.7 RS space cam and copy the 3.0 RS motor specs.

I have wanted to make a stock SC block and cam MFI motor. The stock SC cams are really a very good cam that matches a stock ratio Porsche transmission pretty well. If set up right as a carb motor they often make around 230-240hp in race trim with carbs and have seen one up to 270chp with a very custom EFI and a top notch long block blueprinted to euro specs with the cam timing played with a bit.

The late SC heads would be a better starting point as you could open the ports up to 36mm to match the S injection stacks and that is a near perfect fit with the stock cams. Thus you save on opening up the stacks and buying custom pistons.

MFI pumps are not correlated to HP. They are more tied to TQ.

Your S pump will support around 150# of TQ and a 3.0 build is going to be about 205# as a 3.0 or about 220 as a 3.2. This means even if you get the pumps advance mechanism to come close to matching the TQ curve, you are going to have to run to rich at idle or to lean at RPM.

I would start by contacting a good MFI pump builder and see if they think they can help you to adapt something to your custom build.

For DE's and weekend bombing the SC cams will probably be just as fast and more flexable than S cams. The good news is your S space cam has value and the 2.2 pumps are actually more flexable when trying to do a custom cam and displacement build.

kenikh · 02:49 PM

911st is technically correct, but search for the opus threads by Jeff Higgins on the subject. The smaller parts can work just fine in your configuration. Jeff converted his SC motor into a twin plug, hot cammed MFI monster using a 2.4T pump and small port heads. I've driven it, it works and is every kind of fast you can imagine. The 2.2S pump has more than enough tunability to work fine, as do the 36mm stacks and TBs. They leave a little on the table, but you won't miss it.

Ideally, you'd send the small port heads to Steve Weiner for his spedial sauce and the stacks and TBs to Rennwerks for 41mm taper bore, but with 'S' cams, it isn't really necessary. With DC62, DC80 or custom big overlap cams, it would be worth doing for 8000 RPM potential, but in that case you'd need some R&R/Carillo/Pauter rods, too.

Do it!

Good luck.

BTW, Jeff's car is also used exclusively for DEs at Pacific Raceway in Seatlle, as well as mountain runs. I have yet to catch him.

kenikh · 05-10-2010, 03:01 PM

Linkitude:

MFI Pump - Open Heart Surgery

MFI Open Heart Surgery II - The Fuel Pump

Jeff Higgins · 05-10-2010, 06:21 PM

I would agree with what 911st and Kenik have to say. Stick with the SC cams. That way, you can run the P's & C's you have with no clearance issues.

SC cams are far better on a 3.0 than S cams. The SC cams have a good deal more lift and substantially shorter duration than S cams. The lift will feed the larger displacement better, and the shorter duration will drive the power band down into a more "streetable" rpm range. So, just get an MFI drive to bolt to the left cam, and use 'em. All you need is a larger diameter MFI drive seal than the three bearing towers use, but Henry has them at Supertec. Piece of cake.

As far as port sizes, I started with the later small port heads. I left the exhausts stock (they are the same on either small or large port heads anyway) and opened the intakes to 38mm. Yes, 38mm, for use with 36mm S throttle bodies. This provides a 1mm reversion ledge between the port and the throttle bodies in an effort to minimize or eliminate any popping through the stacks at low rpm. Works like a charm. I would think the 39mm ports on the large port heads could be left alone and would perform much the same way. Granted, SC cams, with no overlap (CIS MAF sensor friendly) wouldn't have this problem anyway. What I'm getting at is that there would be no reason to enlarge the throttle bodies or stacks to match the heads. They should work fine as-is.

911st is right about the pump as well. It will run the motor, but it will be either lean on top or rich down low. There isn't a big enough delta available in its fuel delivery for the larger motor. I settled for rich down low so as not to run dangerously lean on top. As Kenik will attest, however, that first wide open throttle burst can be a sight - and smell - to behold. Once running up high it clears right up, but it does have to "clear its throat" a bit if it's been in slow traffic or something for awhile. But I'm working on that...

BK911 · BK911's Garage

Wow, thanks guys. I was hoping for a bolt on and richen it up a little bit.

Reading Jeff's thread is making me rethink the idea. I dont want to modify original S stuff. I may try to sell again and go with some sort of EFI.

kenikh · 05-11-2010, 12:49 PM

Quote:

Originally Posted by BK911

Wow, thanks guys. I was hoping for a bolt on and richen it up a little bit.

Reading Jeff's thread is making me rethink the idea. I dont want to modify original S stuff. I may try to sell again and go with some sort of EFI.

Jeff's point is that you really don't need to modify it. He is at the bleeding edge using a 'T' pump, but the 'S' pump can handle a much wider fuel curve.

All you have to do is adjust the internals to dial in the fuel curve - even stock 'S' motors have this done. With SC cams, the 'S' pump will have more than enough tunability to get you where you need to go.

'S' stacks and TBs: stock
'S' pump: stock

Machine you heads for MFI injectors and you are good to go.

911st · 05-12-2010, 09:39 AM

The range of hight to low fuel deliver is controled by the differance in the high and low on the space cam.

You can adjust the pump to control how fast the delivery is made with the springs (delivery curve) and you can control the gross amount of fuel the pump can deliver by adjusting the position of the 'rack'.

However, you can not increase the 'range' of idle TQ to peak TQ.

A 2.2S pump's range is about 30+% shorter than needed for a tuned 3.o SC. (apx 50 to 150# v 50 to 200#)

EFI is much more adaptable plus you get full control over the igntion side for even more potental.

Still, I love making CIS and MFI work.

kenikh · 05-12-2010, 09:45 AM

Quote:

Originally Posted by 911st

The range of hight to low fuel deliver is controled by the differance in the high and low on the space cam.

You can adjust the pump to control how fast the delivery is made with the springs (delivery curve) and you can control the gross amount of fuel the pump can deliver by adjusting the position of the 'rack'.

However, you can not increase the 'range' of idle TQ to peak TQ.

A 2.2S pump's range is about 30+% shorter than needed for a tuned 3.o SC. (apx 50 to 150# v 50 to 200#)

EFI is much more adaptable plus you get full control over the igntion side for even more potental.

Still, I love making CIS and MFI work.

One last wrinkle - you can extend the range of any MFI pump pretty dramatically by machining the flyweights to make them lighter. They subsequently open completely at higher RPM, which allows you more latitude in "screw tuning" the rack.

Mark Jung was able to get a 2.0S pump w/ 2.4 plungers and lightened flyweights flow identically to an RSR pump. Admittedly this is more work, but is nontheless pretty simple to do.

911st · 05-12-2010, 10:35 AM

Lightening the flyweights I belive just slows the fuel curve advancement.

To fit a cam with RSR specs where the power curve is much later in the rpm range you would have to increase the spring rates and or lighten the weights. This dose not add anything to gross flow potental. Just delays fuel delivery till latter in the rpm curve.

Changing plungers is a whole different story that few have explored. Put a 30% larger plunger in and you increase the low to high range potental 30%.

I do not know the differance between the 2.o and 2.4 plungers. It is not easy to just find larger plungers and barrels. If some one could CNC them to spec we could have some real fun.

Of cource I can be wrong but this is what I understand to date and it has been ovder 10 years sense I took one apart and tryed to carve my own space cam.

kenikh · 05-12-2010, 10:43 AM

Quote:

Originally Posted by 911st

Lightening the flyweights I belive just slows the fuel curve advancement.

To fit a cam with RSR specs where the power curve is much later in the rpm range you would have to increase the spring rates and or lighten the weights. This dose not add anything to gross flow potental. Just delays fuel delivery till latter in the rpm curve.

Changing plungers is a whole different story that few have explored. Put a 30% larger plunger in and you increase the low to high range potental 30%.

I do not know the differance between the 2.o and 2.4 plungers. It is not easy to just find larger plungers and barrels. If some one could CNC them to spec we could have some real fun.

Of cource I can be wrong but this is what I understand to date and it has been ovder 10 years sense I took one apart and tryed to carve my own space cam.

I am of course simply suggesting ways to "back into" a solution that works. Without a doubt, the right way is to use the right space cam in conjunction with matched flyweights.

Given the limited availability of space cams for big bore motors, I wanted to offer an alternate way to get where you can make the solution work...well.