modify my 2.4E or not ? ??

Sonny · 12-14-2003, 01:59 PM

OK guys, I've been back and forth with the "engine modification or engine transplant" dilema. I have a nice 69E with a 72 2.4E/webbers + sport exhaust. Car runs great and is fairly quick. But like the rest of you I want more zip. If I spend the money to install 9.5:1 JE pistons -valve job ect, will I feel the difference in the seat of my pants or will I be thinking "you idiot! you should'a just put a 3.0 liter in the car"? Also, what are 2.5 pistons and cylinders all about?? Would that require case or cam tower machining? I would like to keep this engine and "work it" because I know the history. What can I do to this 2.4E to have more power without overspending on he car???????

Tim Walsh · Tim Walsh's Garage

If it's a 72 Then it's probably not a 7R case (perfect for a 2.7RS) rebuild but those cases are cheap.

To get some more zip you could swap camshafts to an S profile (not as streetable but lots of fun), have your MFI pump recalibrated, install 85mm JE's(total displacement 2397 from 2341). That should make a nice ~200 HP engine. Up from 165.

I'm doing something along these lines but not quite. I'm going from 140HP T engine to ~175HP E engine (2.2 E Pistons and cams. 2.4 E MFI pump)

In reality it all depends on how much Cash you want to spend. I

jgparker · jgparker's Garage

I think the HC 2.4 you described (with webers or MFI and the right cam) could be more HP than a stock CIS 3.0. What you described is close to a 2.4 911S engine which is good for 190 hp. I believe the CIS SC engine was good for 180 hp when it was introduced in '78. Do you want torque and reliability, or a peaky, high reving engine with great throttle response? If you're looking for personality, go for the early engine. Just my opinion.

JP

BK911 · BK911's Garage

I agree with Mr. Parker. I have a high compression 2.4E engine and it absolutely screams. And is very streetable.

As far as bang for the buck, you might get a decent power gain from tuning the engine. Check the compression. If good, verify/set the cam timing, ignition timing, dwell, new plugs, rotor, cap, etc... A little bit off can make a big difference. Then source an MFI system!

If the compression is off, it may be able to be restored. Then do the tuning thing. If you can't restore the compression, then rebuild.

Tim Walsh · Tim Walsh's Garage

Bk have you ever dyno'ed your car? I'd love to hear some impressions of it since I'm building one as we speak.

jim72911t · 12-15-2003, 08:05 PM

Seems like Tim and I are building similar motors to yours, BK, so I too would love more info. How does it compare to a stock 2.4T or Carrera motor (two motors I've driven recently), for example?

I know, I should just put mine together and see for myself!

Thanks,
Jim

BK911 · BK911's Garage

No, she's never been dyno'd. I would estimate she's around 175hp. I've owned 2.2's and 2.4's with T, E and S engines and a 3.2 Carrera and this is the fastest one I've had. My buddy has a chipped 3.2 Carrera with exhaust and honed intake and I pull away from him. He has more power, but weighs a lot more. I've also pulled away from SC's and early S's. Not to mention all the ricers! Plus she drives real nice around town.

It's a bone stock 2.4E with 2.4S pistons. Nothing real special, but she's been "econo" balanced and blue printed.

I also went with 205/50's to give a little more acceleration. Took a little off the top end but for street use it's no big deal.

That's in a stock 72 Targa. I am building a 2.4E with 2.2S pistons for my gutted out 73 Coupe. I can only imagine how fast she is going to be!

Sonny · 12-20-2003, 08:57 AM

Hi BK, I thought 2.2 and 2.4 ''s were the same bore 84MM?? That being said, what is the difference between the 2.4S piston you describe here and the 2.2S piston you are about to use. I have the 2.4E now. What piston should I put in it the 2.2S or 2.4S ???

Sonny

Jim Richards · 12-20-2003, 09:53 AM

Both were 84mm bore, but the 2.2S was 9.9:1 CR, I believe, and the 2.4S was 8.5:1 CR.

Bobboloo · Bobboloo's Garage

The 2.2S pistons were 9.8:1 CR and the 2.4S were 8.5:1 CR.

Installing the 2.2S pistons with the increased stroke of the 2.4 motor (70.4mm) will give you an increase in the CR of about a half of point to give you 10.3:1 CR when installed in a 2.4 motor. This is considered twin plug territory but I've heard of people doing this with no problem running single plugs. A safer alternative would be 2.2E pistons on a 2.4 motor to get a CR of 9.6:1.

Another option is a custom set of JE's. 9.8:1 is considered safe with single plugs.

Putting high compression pistons won't give you a S motor because to do that would require porting and changing the induction$. I think however that a high compression 2.4E , despite having slightly less HP, is a better street motor than a 2.4S anyway and might even be faster than a stock 2.4S in the quarter mile.