2.4 from 2.2

[steveW]

I've just had an idea!!!!

If I was to put a long stroke crank from a 2.4 into a 2.2T, would I get a 2.4 that delivers more oomph than a std 2.4T?

cheers

[724doorE]

Ahhh, yes, but you will need the rods for the second crank as they are different as well.

[steveW]

Thanks Dennis.

If I look at the 2.2 T with an 8.6 cr, and a long stroke crank and rods what would I end up with? Surely it wouldn't ne like a 2.4 S otherwise everybody would be doing it.

It seems like a very simple upgrade, so why have I never heard of anyone doing it?

[724doorE]

No, not an S but, I think you can assume about half a point increase in your compression ratio when increasing the stroke in this manner. A similar trick has been to use 2.2 T,E,orS pistons (all 84mm) in place of lower comp 2.4 T,E,orS pistons. A 2.2 S was 9.8:1 and a 2.4 S was 8.5:1 (factory comp decrease due to emmisions andcrivability) So you put those 2.2S pistons in a 2.4 engine and you have a nice comp increase. Of course to realize the complete benifit you would need to use bigger cams and have your heads and intake ported. Food for thought none the less.

[steveW]

According to Bruce Anderson's book the 2.4 E and 2.2 T both had 32mm port.

My maths isn't very good, but what would the comp ratio work out to and will 'E' cams clear std 2.2 T pistons in something like this. The reason I'm asking is because I believe 'T' cams can be reground to 'E' profiles.

[steveW]

Why is it that nobody, apart from Dennis, seems interested in this line of thought?

Surely it isn't so ridiculous!!

[724doorE]

If they have 10K they only want to talk about 3.6's

I'm poor, so i'm intrested in the early mag engines.Off the top of my head, I don't know, but you have Briuce's book, so find the mods part where he talks about the 2.2's and 2.4's. He mentions in that section about the use of 2.2 pistons in 2.4 engines for improved performance due to comp increase.

Also check to see if there is a difference in head gasket style, JW would know for sure.

What i would do: long 70.4 crank/rods. find some 2.2 E or S pistons good used would be ok for me, Get those cams reground to at least E spec, I'd like more although a good solid 2.4 E will run hard. Then I would have the heads ported to S spec 36mm. (I'm contemplating going 38mm on my 27RS bastard engine) I assume you have carbs, so have those manifolds ported too. figure out the right jet sizes and have a blast. Should give you a 2.4 witharound 10:1 comp and factory 2.4S was 190 hp at 9.0:1 (Iwas wrong earlier), sooo should be fun and relatively inexpensive. Yes T&E had the 32mm ports

[steveW]

Dennis, what is your 'bastard' 2.7?

My thinking is that seeing as though I need to attend to case studs and strip the motor, I might as well give it some more oomph. I can get a crank and rods (will have to check why it is available though?).

'E' or 'S' pistons might be difficult to find over here, so i was thinking of keeping mine (compression seems okay) and figured the simplest way was fitting a long crank and rods. BA waffles about it without saying anything that makes sense. I've got Zeniths and a Marelli dizzy which might be a bit limiting though.

My ideal motor would be a wicked 2.5 or something - a little screamer.

[BK911]

You can put a 2.4 crank and rods in a 2.2. The MFI will have to be richened up a little, or the carb jets reamed a little. You can also put 2.2 pistons in a 2.4 without changing anything. Check all clearances though.

A 2.2T piston has a little more displaced volume as a 2.4S piston, but is much heavier and doesn’t have the deep relief pockets. So a 2.4 with 2.2T pistons will have a slightly higher CR as a stock 2.4S. But as Dennis said, you won’t have the same power without some head work, cams and injection. A 2.4 with 2.2E or S pistons? Wow!

MY OPINION: The best early street engine is a high compression 2.4E engine. This can easily be built with any 2.2 or 2.4, T or E core. I’m getting excited just thinking about it!

BK

[racea911]

I am planning something along these lines with my 2.2T engine with Webers. I will decide what to do once I get inside my motor and see how my pistons and cylinders look. If my pistons and cylinders look great, I plan on re-using them with a 2.4 crank and rods. I will leave my port sizes the same and go with either E grind or Solex grind cams. My compression should be about 9:1 which is a full point higher than a 2.4E. With the Solex (between an E and an S cam) grind cams and the higher compression, I think I will be pushing about 10-15 more hp than a stock 2.4 E. The cams should make it a little more revvy than a 2.4E and a little better around town than an S motor.

[724doorE]

Was a 2.4E, now has 2.7euro RS pistons and cylinders Ecams 34mm ports and stock E mfi. Looking to finish the deal with S cams and 38mm ports and mfi work.

I kept my 2.4E pistons, now I wonder if they would go well with a spare 66mm crank I have for a low comp. 2.2 twin turbo.....hmmmmm projects and ideas just abound with little headway made

[Zeke]

I asked this same question over on the 911 engine rebuilding BBS. Here are some more answers: 2.4 crank for a 2.2