Mfi Conversion

[SSCenter]

HELP.I WANT TO TAKE A 2.2S MFI AND PUT IT ON A 2.7 WITH RS PISTONS( 8.5) WITH E CAMS .I SEE THIS DONE WITH S CAMS BUT NO ONE HAS COMMENTED ON E CAMS. HELP HELP DON

[KobaltBlau]

Should be fine. Are you worried about valve to piston clearance or MFI fuel delivery? valve to piston clearance is no problem, MFI pump can be adjusted and should be no problem either, as per henry's comments on a recent thread on S pumps on RS spec motors.

[SSCenter]

ANDY. I AM NOT WORRED ABOUT PISTON TO VALVE.I WANT A STUMP PULLER.I WANT TO STAY AWAY FROM THE S CAMS .WOULD ANOTHER CAM WORK BETTER?SOLEX????I AM ALL EARS DON

[69911e]

I just put together a 2.7 E cam motor. The engine is great at low to mid RPMs, but HP drops off fast at high RPMs (about 6K). I will find out this week is it is good for Autox. The good part is the 0 to 60 time is very fast.
I don't think this would be a good engine for the track. If you have some S cams I would put them in. It appears the E cams have to little lift for the 2.7 valves at high RPM.
I can post a HP chart if you are interested.
As for the fuel injection, it sould be fine with an adjustment in the rack (the E and S cams are very similar until they hit high RPMs). If it does not work well, I would trade my extra 2.4 E space cam (the same kind I used in my car) for the 2.2S one you have.

[KobaltBlau]

Oh I see now Don. E cams will just give it more low-down, which would be better for you. solex cams are a little more toward 'S' cams. People using MFI don't usually go much milder (torquier) than an 'E' cam on this type of motor. I don't see people using a 964 cam or 20/21 with MFI, but it's possible. I don't think you would be disappointed with the 'E' cam. If you want more of a "stump-puller" than 2.7+MFI+E you probably want more displacement. It's hard to go much bigger than 2.7 on a 2.2 base so you'd have to get a 3.0 or 3.2 and make it into a 3.2 or 3.4 or just buy a 3.6. If you already have the 2.2S and want to rebuild it then 2.7 is good.

ED, what does semi-active suspension mean? just standard 911 hydropneumatic or something different?

[SSCenter]

ED,I LET ME GIVE YOU THE WHOLE PICTURE.EARLY ALUM. CASE.RACE PREPED,CARRILO RODS,CASE CUT FOR 2.7 OR 2.8,2.7S CRANK,2.2S MFI. I WANT A STUMP PULLER CAM,THATS WHY I WAS THINKING SOLEX.E.OR CUSTOM CAM.TALK TO ME.DON?????????????????????

[KobaltBlau]

DON, people with an engine like that normally want to spin it to high RPM. the E cam is the best choice for torque I know people have used regularly on MFI engines. There are certainly other options, but I don't know what a good cam for a torquier engine with those specifications would be. Maybe 'camgrinder' can chime in.

[69911e]

SSCenter, I see little reason for special case work or rods on a low rpm engine. For your "stump puller", I think you should consider a bigger engine; a 3.0,or 3.2 can be done for similar cost to a 2.7 and will have more low end. If you really want MFI you can even put it on a 3.0 with pump modifications.
I am very far from an expert on this subject, others on this board , may chime in.
What are you building the engine for? Street, AutoX,or Track?
What parts do you already have?

KobaltBlau, something very different. I would be supprised if anyone is still running the hydropneumatic suspension anymore (unless concours).

[KobaltBlau]

Originally posted by 69911e
SSCenter, I see little reason for special case work or rods on a low rpm engine. For your "stump puller", I think you should consider a bigger engine; a 3.0,or 3.2 can be done for similar cost to a 2.7 and will have more low end.

I concur. 3.2 can be taken to a 3.4 pretty easily.

Here's a "stump puller" idea:

3.2 base
stock ports, intake manifold
SSI/early heat exchangers
cylinders bored to 98mm and replated nickasil
98mm 9.5:1 JE wedge shaped pistons
Stock or maybe elgin SC 330 cam

that's only a couple of grand more than a 3.2 stock rebuild. keep it at 95mm and all you have is a stock 3.2 with early exhaust. would really feel like a 'stump puller' in a light car.

the other option is a (relatively) small turbocharger with 8-8.5:1 compression, but that's a rarely trodden path, major project.

[emcon5]

I don't have it here, but I seem to remember a dyno sheet of a E cam 2.7 in Bruce Anderson's book, in the "Engine modifications" chapter.

I could be wrong though.....

Tom

[camgrinder]

I have an idea for a cam between the E and S.
The easiest is a solex cam ground on E lobe centers.
Taking the solex from 97 L/C to the E 102L/C flattens out the power band.
I think my "custom cam" on this list would make more power than an E or solex. With a lot of torque.
http://home.earthlink.net/~camgrinder/911/27mficc.htm

Stock valve springs would work up to 7000 rpms. After 7K I would run aftermarket springs and Ti retainers.

[KobaltBlau]

ooh, that looks neat, John!

[SSCenter]

JOHN.THANKS FOR YOUR INPUT.THIS IS THE SAME PERSON THAT CALLED YOU LAST WEEK ON SAME CAM.THANKS

[emcon5]

Originally posted by emcon5
I don't have it here, but I seem to remember a dyno sheet of a E cam 2.7 in Bruce Anderson's book, in the "Engine modifications" chapter.

I wasn't wrong. There are 2 of them on Page 140, a 2.7 with RS pistons, E cams and Webers. One is a torqe/hp graph, one is a HP comparison with a RS engine.

It is hard to read the scales in Bruce's charts, looks like a little less (5-10) HP than an RS, peak is ~500 RPM lower, with more power down low.

Tom

[jluetjen]

Camgrinder. Ed and I were discussing something similar off-line. Looking at the way the torque dramatically plummets on his engine at higher rev's we were wondering if maybe the engine was suffering some from lack of lift. Ed adjusted the mixture some and determined that it's running rich at the top of the rev range even though he's got an E-MFI pump. Theory number one is that the engine is just running out of air. The S ports should be more then adequate as well as the valve size since they are the same for the RS. Furthermore, the port flow will support lifts up to at least .5 inches.

Looking at the different cam options, I was wondering if getting a set of 964 cams ground with E lobe centers would be an improvement, or else the 993 profile for mechanical lifters on E lobe centers.

Your thoughts?

[Eagledriver]

I have a set of Solex cams that came out of my 2.7 MFI engine. It had lots of torque and pulled strong to 7000 RPM. The torque was such that you couldn't get to full throttle in first gear before breaking loose the rear and hitting the redline (Non LSD tranny). The power of the engine measured about 184 at the rear wheels according to my G-tech.

I now use "S" cams since my car is primarily a race car. It has 204 HP at the rear wheels and only slightly less torque at low RPM. The "S" cam has a noticable "cam effect" around 4500 RPM whereas the Solex just pulls strong everywhere. The MFI worked fine with both set-ups. (RS space cam).

-Andy

[camgrinder]

John, I agree. The valve is not open long enough to feed the engine at high rpms. I also agree extra lift is needed.

The 964 is a good idea to replace the E cam.

The custom cam has duration very close to the Solex cam, with more valve lift . Going from 97 or 98 lobe centers out to the 102 will flatten out the torque curve. Remember the original S and Solex cams were designed for 2.0L and 2.2L litre engines. The increased displacement of the 2.7Llikes a wider angle.
Compare the 906 (96 L/C) to the 3.0L RSR (101 L/C)

I updated the spec sheet to include the 964 profile for comparison.



http://home.earthlink.net/~camgrinder/911/27mficc.htm

[jluetjen]

Ed asked me to post this since he couldn't get the data into a .jpg.



PS: Thanks Camgrinder for the updated information.

The increased displacement of the 2.7 Llikes a wider angle.

Any idea why this is? An of the cuff theory -- the extra mass of air from the larger cylinder carries more inertia and thus doesn't need as much overlap in order to get complete cylinder filling(?). I don't know.