2.4L increased to ????

[tocobill]

I have a 2.4L out of a 73 911 T. I was looking at LN Engineering site. What the largest size piston and sleeve that can be run with this size engine/case? Thanks.

[Henry Schmidt]

We run 86mm Biral barrels in most of our 2.4 (4R) builds because they are reasonably priced and slip right in.
That said, with Nickies you have a much greater range of choice. What it ultimately comes down to is budget and expectations. What do you want out of your engine. If you simply want it larger I believe Charles makes a 92mm cylinder that can fit a machined 4R case.
That would be excessive (spigot bore gets very thin) but if you're running at low RPM and low compression you can get away with it.
For longevity, we try to leave the spigot bore standard and work around that number (91.5mm from memory). With a 91.5 mm spigot I would think that something less than 88.5mm (assuming a minimum .060" cylinder thickness) might be the maximum even for Nickie.
There were quite a few 73 2.4 engine built with a 7R case and in that situation you may want to bore the case for larger cylinders.

[tocobill]

Originally Posted by Henry Schmidt

We run 86mm Biral barrels in most of our 2.4 (4R) builds because they are reasonably priced and slip right in.
That said, with Nickies you have a much greater range of choice. What it ultimately comes down to is budget and expectations. What do you want out of your engine. If you simply want it larger I believe Charles makes a 92mm cylinder that can fit a machined 4R case.
That would be excessive (spigot bore gets very thin) but if you're running at low RPM and low compression you can get away with it.
For longevity, we try to leave the spigot bore standard and work around that number (91.5mm from memory). With a 91.5 mm spigot I would think that something less than 88.5mm (assuming a minimum .060" cylinder thickness) might be the maximum even for Nickie.
There were quite a few 73 2.4 engine built with a 7R case and in that situation you may want to bore the case for larger cylinders.

Thanks for the info. Im debating on a 3.6 re-power or to rebuild the 2.4 engine I have and throw it in my RSR build. Will the casing stamp tell me whether its a 4R or 7R. The thought of staying with the 2.4 and increasing the bore is because I have everything for the engine including the MFI system. Im sure it wont put out the same power as the 3.6 but how close could i get it? Thanks.

[tocobill]

Its a 7R case. Took a look at the pics I had taken of the case.

[tocobill]

So Henry .... I done some research about the 7R casing machining. I cant find anything on the max limits of what it could be bored out to? I found 2.8 and 2.9 but nothing higher then that ... any thoughts or advice? Would it be better to just do the 3.6 or put the money into the block and parts I have? Thanks.

[Henry Schmidt]

I think I would build a 3.2 short stroke MFI engine if I were considering an RSR build.
Use a converted version of your MFI and sell off your 2.4 long block to purchase a 3.0 core.
Here is the last RSR engine project we built.
It is a SS 3.2 MFI twin plug.

[tocobill]

Thanks Henry. Ill have to do some more research. This looks like a better route then the 3.6. I appreciate the advice.

[Lukesportsman]

The good thing about buying an engine from Henry: even if it didn't run, you'd have a nice piece to put in the living room.

[Cotton175]

I appreciate the advice.