2.4 T Most Effective Modifications?
 

The thread on 2.4 T power has gotten me to thinking. Comparing Josh's dyno chart to my own results on the dyno surprised me a bit. To recap from that thread, I have a dead stock "T" spec motor with a sport muffler; Josh's motor has the oft recommended 2.2 "S" pistons and cylinders (raising compression significantly) but otherwise sounds exactly like mine. What I found surprising was the relatively modest power gain shown with that modification. Granted, different cars on different dynos under different conditions, but I would have thought it was good for a lot more.

My motor only has about 40,000 miles on it and runs like a champ. I was planning on tearing into the top end only, to swap to the 2.2 "S" piston/cylinder set and install some Elgin "Mod S" cams, plus the required space cam swap and throttle body boring. But now it seems as though the compression increase may not provide that great of a "bang for the buck", especially with new Mahle sets going for darn near $3,000, and good used ones being pretty hard to find.

So the question of the day is how much would I be giving up by sticking with my "T" piston/cylinders? Also, is there enough valve clearance when running "S" or "Mod S" cams with stock "T" pistons? Would I have to have valve clearance pockets deepened in the pistons?

I'm also kind of wondering if just changing the cams would be worth it. In other words, do these two mods compliment each other, kind of like the whole being greater than the sum of the parts? Maybe that is where Josh's motor is at; some cams would have helped it see some much bigger gains. I just don't want to wind up in relatively the same boat, with all the work going into changing cams for a relatively modest gain. Thoughts?

There's not enough valve relief in the T pistons for the S cams. They would need to be machined. This will of course lower the compression even more than it currently is.

Another thing to keep in mind is the overlap of the S cam will rob some of your compression as well.

I rebuilt a 2.4T motor before and thought it to be a great motor without much room to be improved upon for street use. The only thing that I felt you could do to improve it for that purpose was the compression increase, that you've mentioned, to improve the low end torque a little. Aside from that the next best improvement would be to replace it with a bigger motor.


Let's backup for a moment though. What's your intended use for the car? Street, occasional DE, autoX, or full race car?

In my opinion for anything but a full on race motor I would leave it just the way it is. I'd even put the stock exhaust back on it.



P.S. Ruling the world is highly overrated....Drinking Irish whiskey on the other hand isn't. :)

From what I know about my car and motor, it was purpose built to autoX and I'm guessing that the motor was a cheater. The T cam was kept to make it appear as a T, yet it had as much power as the Es (that I believe were in a higher autoX class). The compression bump would be tough for anyone to figure out.

Intended use should be the driving force behind your mods. As you said, Ps and Cs are getting expensive and if you're talking about cams, MFI changes, etc...you might consider building up a 2.7RS spec. I'm going a step further than that and planning on a 2.8L (need to stay within race classes). For less than the cost of any of the rebuilds, you could buy a nice 3.0 or 3.2 that someone is ditching for a 3.6. And of course, there's always the 3.6 conversion.

2.4 T Most Effective Modifications?

3.6...

+1

2.4T motor is a great motor that will run forever.

Josh, what class do you plan the run the 2.8L?

If for the street, I'd think at $3k for 2.2's why not slide in some 2.7 cylinders with 9.5 JE pistons, E cams and appropriate MFI mod's. It will have more bottom end and still breath OK to pull 7grand. Then again, this is what I have in her with stock RS (8.8) pistons and I have a 3.0 sitting behind her on a jack :(

bkreigsr,

can you list what mods you have done to bring your
2.4 to 200hp?

i will be working on mine soon once its out of the
paint shop in early feb.

I've pretty well established how I use the car over the last few years. It is primarily a street car; a semi-daily driver at that. It sees at least one or two track days per month. It is a very "drivable" car in traffic and what not and is quick enough to be a lot of fun at the track days. I drive it somewhere between 10,000-15,000 miles per year.

My plan has always been to go with the 2.2 "S" P and C's, along with the Elgin "Mod S" cams. I'm hoping for 180-190 horsepower. Another option I'm considering is the 85mm JE pistons in my iron "T" barrels. The key here for me is to do the mods without splitting the cases, so the 2.7 P and C's are out. Wouldn't a high compression (9.5-9.8:1) 2.4 or 2.5 br pretty darn close to a low compression RS spec 2.7?

I have considered the 3.0 or 3.2 swap. A very high priority for me is to retain the MFI. Another thought has been a 3.0 with JE pistons and the Mod S cams running on MFI, but the 3.0 is out of my budget range for now. Warming over my 2.4 is within reach, and I can do all the work myself. It would basically be parts swapping with no machining if I go the high compression hot cam 2.4 route, and that appeals to me. What do you all think of the JE's in the iron "T" barrels as a cost saving measure over the Mahle 2.2 "S" P and C's?

This 2.7 approach is easily a $10k project.

I did 86.5 pistons from weisco and bored the cast cylinders. This makes a nice high compression 2.5. I'm also running elgin mod s cams and 2.7 rs stacks ported heads and a 2.8 rsr injection pump runs great on pump gas.

At least. Why not transplant a 3.2 into your car?

If its an entire build, sure. Why would the cost of new P & C's be so much more than pistons in existing C's? He's already pulling the heads and cam towers, changing the MFI, boring the TB's and willing to change exhaust. Where is this "extra" cost you are all talking about over what he suggested? Sure you can argue that changing P&C's could lead to a full blown case cracking full on rebuild. But, why?

What am I missing?

By the way, I'm talking bored tb's also and not some high butterfly tb's or anything special. Bore the thing out to S spec, drop in some E cams and the larger P&C's. I'm not suggesting its inexpensive, but just can't see why its so more than what he proposed.

Luke, the additional cost in going with the 2.7 or 2.8 P and C's is in boring out the case to accept them. Then I would be looking at a full tear-down and the machine work on the cases. My motor is pretty fresh, and the bottom end is rock solid. I'm looking for "bolt-on", which I can achieve with either the 2.2 "S" P and C's, or the 84 or 85mm JE's.

I think my original questions were answered above. Bobby states what I suspected - my 2.4 "T" pistons won't clear the valves with "S" cams. That pretty well settles it; I need new pistons at least anyway. Even if Josh's "cheater" motor doesn't show a huge increase over a stock "T", since I need new pistons to support my cam change, that's not a cost it looks like Ican avoid.

So the new question is, Mahle P and C set ($3,000) or JE pistons in my iron cylinders ($900)? Are the Mahles worthwhile enough to justify that big of a price difference? Remember, street driven for the most part, but part-time weekend DE's as often as possible.

i say either leave it as is and enjoy it or swap it. it's surprisingly fast the way it is now.

maybe you want a hot rod 2.7 or 2.8, in which case be prepared to pay. otherwise, put in a 3.0 or 3.2 depending on your tastes. (these run in the $4k-$7k range all day long, depending on whether it's been rebuilt or not.)

I have a stupid question. Will E cams work with T pistons? Is there any point?

I have been thinking about doing a top end rebuild (incluidng the pump and throttle bodies) on my car to repair ever so slightly worn valve guides and to clean up a couple of oil leaks. I figure if I have it apart I might as well do some kind of upgrade.

Don