MeanRex

Anyone have any good pictures of seperated cylinders and crankcase.
And what size cylinders can fit on a 2.4l case.
And whats the diff between 3R case and 7R, was 3R 2.0-2.4? and 7R 2.7?

Jim Florance

I just finished a new track motor for my '70 911T. I took a 2.4 motor up to 2.9liters. Mahle has had this piston /barrel upgrade available for the past year or so. To my knowledge, this is the biggest you can go with a 2.4 The engine screams!!!

MeanRex

Does Mahle have a website?

Steve Weiner-Rennsport Systems

[quote]Originally posted by MeanRex:
<strong>Anyone have any good pictures of seperated cylinders and crankcase.
And what size cylinders can fit on a 2.4l case.
And whats the diff between 3R case and 7R, was 3R 2.0-2.4? and 7R 2.7?</strong><hr></blockquote>

Hi:

You may install 2.7 (90mm), 2.8 (92mm), 2.9 (93mm) P/C's into your 2.4 case, but the case spigot holes must be machined larger to fit. All of these use the same bottom diameter (97mm).

The differences between the 3R, 4R/5R and 7R cases are in the internal webbing. the 7R cases are much stiffer due to more webbing and bracing inside them. These are much preferable when building a large displacement mag-cased engine as they do not flex as much and are much more stable.

One may use the 4R/5R 2.4 cases when RPM's are not going to see much 7000 RPM use.

2R/3R's were used on 2.0-2.2, 4R/5R's were used on 2.4, and 7R's were used on 2.4 & 2.7 engines.

MeanRex

Thanks a lot Steve.
Your site has a lot of helpful info on it too.

And can you use any different conrods/porsche con rods to stroke or destroke it?

Steve Weiner-Rennsport Systems

[quote]Originally posted by MeanRex:
<strong>Thanks a lot Steve.
Your site has a lot of helpful info on it too.

And can you use any different conrods/porsche con rods to stroke or destroke it?</strong><hr></blockquote>

You cannot alter the stroke of any engine by changing rod lengths,......one must change the crankshaft stroke to increase/decrease displacement. Longer rods are used in some racing engines to change the torque curve and peak power, depending upon the port flow velocities, camshafts, and some other things,...

MeanRex

D'oh. Mustve been one of my rotarian slips.
I'm a rotary guy, but I try to learn about all cars that strike an interest in me. Helps keep me sharp, and clue me in when the time calls.

What about swapping around different crankshafts? Will they fit.

I saw that the stock 2.4 (I'm not sure if the 2.0 and 2.2 shared its crankshaft also) was pretty strong (one piece i think), but didn't like to rev too much past 7kRPM

Thanks <img src="graemlins/bigok.gif" border="0" alt="[thumbsup]" />

Steve Weiner-Rennsport Systems

[quote]Originally posted by MeanRex:
<strong>D'oh. Mustve been one of my rotarian slips.
I'm a rotary guy, but I try to learn about all cars that strike an interest in me. Helps keep me sharp, and clue me in when the time calls.

What about swapping around different crankshafts? Will they fit.

I saw that the stock 2.4 (I'm not sure if the 2.0 and 2.2 shared its crankshaft also) was pretty strong (one piece i think), but didn't like to rev too much past 7kRPM

Thanks <img src="graemlins/bigok.gif" border="0" alt="[thumbsup]" /> </strong><hr></blockquote>

Quite all right,... I too, have my moments,...

You can use either the 66mm stroke crank or the later 70.4mm one. They are both damned strong and each has its advantages.

The 66mm one (2.0 & 2.2) is the most bulletproof and is safe to beyond 8500 RPM if its prepared properly. The 70.4mm ones (2.4 & 2.7) make better power but the 6-bolt version tends to shake its flywheel loose precisely at 8000 RPM and this must be considered. These are also bulletproof to 8500 if the flywheel can be kept secured and the crank's oil passages modifed to suit.

Given the RPM range of street cams that people use; "E", Solex and "S", any of these crankshafts will never give you any grief or cause for concern.

MeanRex

Thanks again

I started making a list of the different engine sizes throughout the years, so far I found all but 3 ('73 2.8l RSR, 3.4l and 3.6l) on Pelican Parts 911 spec sheet.
I went to supercars.net to get the RSR (which I couldve just looked at your post about piston sizes to figure out), and I got the 3.6l (2k2 targa) from supercars.net while I was there
But noticed that a 96 turbo had 100mm bore, 76.4mm stroke and 3600cc displacement.
Is this right? or is supercars.net just off on their facts (which I've noticed on other cars before).
I also found the 959 info on supercars.net

I included some stuff you said in this thread and stuff that I found around the internet also, but I'll only put up the bore and stroke chart for now.


Engine Size Bore Stroke
2.0l (1991cc) 80mm 66.0mm
2.2l (2195cc) 84mm 66.0mm
2.4l (2341cc) 84mm 70.4mm
2.7l (2687cc) 90mm 70.4mm
2.8l (2806cc) 92mm 70.4mm '73RSR
2.8l (2849cc) 95mm 67.0mm 959
3.0l (2994cc) 95mm 70.4mm
3.2l (3164cc) 95mm 74.4mm
3.3l (3299cc) 97mm 74.4mm
3.4l
3.6l (3596cc) 96mm 82.8mm

I've also been searching for '73 RSR stuff and havent found too much yet.