2.2L VS. 2.5L Please! Help Me Decide On My Rebuild

[The Barron]

Enter the sub 14psi gang in fat cars with autos. The 2.5L is sweet for us.

[turbovanman]

Quote:

Originally Posted by Turbo Charger Personally.. I don't see any point in using a 2.5 engine unless A. You drag race and can use slicks. B. You can afford Street Legal slicks every year or 2. (however long they last) The 2.2 Already makes GOBS of torque and the only thing a 2.5 is going to do for you imo is make you spin more than the 2.2 already does. All in all the 2.2 is the better choice for most people. We all know its better in the top end and what good is more torque that you can't use?

I agree to disagree. How many people actually drag race there car at the track? 5% maybe. On the street, torque gets you off the line. If you can run lower boost, its easier on the engine and gets you going easier.
My .02 cents.

[capev86]

carrol shelby put it best: "horsepower sells cars, torque wins races!"

2.5 and manual tranny are the best choices, except for drag racing where 2.5 and "built" auto are king! gary donovan has proved this!

the lebaron is a reasonably load, so a 2.5 will have more umph to get you down the road. on n/a cars, the difference is night and day, especially with an automatic. id gather it is the same with turbo cars. the bigger engine gets you more for your dollar and gas mileage stays the same. i have NO problem winding up a 2.5 w/ an 8 valve head. a lot of revvs means nothing if you aren't producing power too. the 2.5 will exceed the 2.2 in hp and torque output, all else being equal (car, equipment, etc)!

for racing, id say drop the balance shafts. for a smooth street perfomer, keep 'em as they add up to about 10-15 hp at most at WOT, which translates to about 3 hp about cruising rpm. better to do the oil system mods (thedodgegarage.com) and run Mobil 1 synthetic to make up the difference.

i personally prefer the 2.5 in any mopar fwd - light or heavy. you just plain get more for the same amount of work! and its sooo much fun having a big 2.5 to differentiate yourself from all those little short-stroke rice burners running around!

[glhsken]

2.2's and 2.5's have the same stroke. All said and done. Aa 2.2 and a 2.5 with the same mods, the 2.2 will make more whp. The 2.5 more torque. Both have too much grunt for street tires.

[turbovanman]

Quote:

Originally Posted by glhsken 2.2's and 2.5's have the same stroke.

Sorry Ken, have to disagree! The 2.2's stroke is 3.62", the 2.5's is 4.09" Thats why the pistons and crank are different and the 2.5 makes more torque,

[glhsken]

DUH... You are right... Early when I typed. I was thinking bore.

The rest was correct though..

[turbovanman]

Quote:

Originally Posted by glhsken DUH... You are right... Early when I typed. I was thinking bore. The rest was correct though..

Heheheehehe, no problem Ken, have to keep you on your toes, as you are the 3 blocker,

[DirectConnection]

Quote:

Originally Posted by The Barron Thats something for old/deaf people to do.. or socker moms..or wives or incoherent people. I have NEVER sat in a 2.2/2.5 chrysler..and a lot of 4cyl domestics and couldnt tell it was running. And us with the EXHAUSTS we run.. man you'd have to have a MAJOR buzz on to not know it was running. MY car with 3" billet, 4" tail pipe and light sound proofing.. well... you figure it out.

I admit I did this once in the staging lanes at the strip. I was next in line to do my burnout, but we had to wait for a few mintutes due to a track condition. There were drag only rwd cars with open headers surrounding me and when they started the lines back up, everyone was starting their cars.. ooops...mine was running all the time.

[DirectConnection]

Quote:

Originally Posted by Tim_K All these responses, and NOT ONE person has brought up the issue of "What if a 2.5 had some top end work?". An 8 valve 2.2 may have more top end than a 2.5, but we seem to be comparing engines with stock heads and exhaust manifolds. In other words, the same air flow capacity with increased displacement. In that case, it doesn't take a genius to see that a 2.5 will drop off earlier, because its flow requirements aren't being met.

If all mods being equal, the 2.5 will still not make as much peak HP as the 2.2, yet make much more peak torque. The displacement has increased, but the valve area is the same for a 2.2 and 2.5, so the 2.2 gets the advantage again.

Quote:

I say that with a fairly well ported head and exhaust manifold, and perhaps a .63 turbine housing, a 2.5 can pull as hard or harder than any similarly built 2.2. A 2.5 has 13.3% more cubic inches to feed than a 2.2, so to have a fair comparison, the head on the 2.5 must flow 13.3% more than the 2.2 head.

Just because engine "A" has more displacement than engine "B" doesn't necessarily mean it will create more HP with the same hardware... ie cylinder head, intake, exhaust manifold, etc... It's not like comparing a 440 to 383. In the case of the 2.2/2.5, they have pretty poor reciprocating geometries. The 2.5 is a stroker and the poor rod ratio gives the piston unreal piston velocities that inhibit HP no matter what kind of cylinder head you put on it.
A 2.5 could easily kick the 2.2's arse in peak HP, but that would be with an entirely different shortblock combo. Mckissick was on the right track years ago. 2.5 tall block and a clean sheet of paper for the stroke, rods, and pistons. This is *MY* ideal combo.... someday (16v) but that will cost some $$.

The original post of this thread was which is better? I have a completely built 2.5 waiting (for sale btw;-) for my Shadow this summer. I wish I went 2.2 as 1/4mph et is my #1 concern as HP wins *drag* races. But from what I've been told, the 2.5 can't be beat with it's off boost response, boat loads of torque, quicker spool time,etc. For road racing, autocross, or street terrorizing, I would say the 2.5 is better suited. But, Pat makes a good point about too much torque.

Quote:

Stroker cranks have become popular in both big and small block Mopar V-8's in the last few years. Why? Because they produce a lot more low and mid range power, and they drop the hp peak rpm. You don't have to kill the engine by winding it to over 6000 rpm to get decent hp numbers.

Actually, it can be just as hard on an engine due to that huge "lever arm" of a stroke, and the possible sacraficing of decent rod ratio. My stepfather had a 426 Hemi Challenger. He used to wing that thing up to 7k quite often. (mild mods). After he got the 472 Hemi, he was told to keep it under 6,500 due to the increased mass, etc...

[rodjake]

hmmm

[turbolaser316]

I have a quistion on this. what kind power would the 2.2l t1 if it was bored out to the 2.5L. if that is posible? or would it be better to just run the 2.5L, plus i have heard that the 2.5L block can handle more boost than the 2.2L by way far.

[turbovanman]

Quote:

Originally Posted by turbolaser316 I have a quistion on this. what kind power would the 2.2l t1 if it was bored out to the 2.5L. if that is posible? or would it be better to just run the 2.5L, plus i have heard that the 2.5L block can handle more boost than the 2.2L by way far.

Bore and blocks are the same. The difference between 2.2 and 2.5 is stroke, this is done by the crank and pistons.

[juxsa]

I am building a 2.5 for my CSXT. Main reasons are that the 2.5 makes lots more torque then the 2.2 so as far as a street car it should be a bit more responsive. I am putting a Turbonetics Super 60 with the .63 housing on it. On a 2.2 there would be so much lag with that size turbo, but a 2.5 will be able to spool that sucker quick. I think for a Drag car, then a 2.2 would be the way to go but as far as a daily driver then the 2.5 all the way.

Sure, the 2.2 can make way more HP, but not with our heads. My buddy and I are doing a 16v hybrid on a 2.2 for his car. Our plan is to have that thing rev up to 10k-11k rpms. With those kind of revs he should be making alot more hp then I ever could with my 2.5.

[johnl]

I love long stroke engines. I like their power characteristics. In the end, however, if you want to go faster, you need a short stroke and a big bore. It all boils down to piston speed. A long time ago, I learned that automotive engineers, considering the metallurgy of stock materials, steel crank/rods and aluminum pistons, limit maximum piston speed to about 4500 feet per minute - even in race engines. Yes, you can go higher but not for long, or, unless you go with exotic materials.

Turbovanman reminds us that the 2.2's stroke is 3.62", the 2.5's is 4.09" and DirectConnection notes that "In the case of the 2.2/2.5, they have pretty poor reciprocating geometries. The 2.5 is a stroker and the poor rod ratio gives the piston unreal piston velocities that inhibit HP no matter what kind of cylinder head you put on it."

So -
At 7000 RPM, a 2.2's piston is going 4223 feet per minute.
[3.62" x 2 = 7.24"/R, 7.24" x 7000 RPM = 50,600"/M, 56,000"/12" = 4,223 FPM]

At 7000 RPM, a 2.5's piston is going about 4,771 feet per minute.
[4.09" x 2 = 8.18/R, 8.18 x 7000 RPM = 57,260"/M, 57,260/12" = 4,771 FPM]

So, even if your head can breathe at 7000 RPM, you are up against the limits of metallurgy and your next step will be super duper reciprocating parts. Not coincidentally, that's about the same engine speed that your valve train loses control of the valves - for the same reason - stock metallurgy.

That's where the short stroke engines ultimately win. Darn it. They lower piston speeds with shorter strokes while they are increasing RPM to pump more air per minute. To deal with a valve train that is now moving even faster, they reduce the mass they have to control with exotic metals - titanium, and by shrinking the parts - 4 & 5 valve heads and pneumatics or as with Ducati, desmodromic valves.