Problems? -2.2T/E Pistons in a 2.4
 

I am doing a rebuild & considering 2.2T/E pistons to put into my 2.4T looking for a compression bump along the lines (but less, obviously) of one of Wayne's "favorite motor" setups. I am also upgrading to 'E' cams for a what I hope will be a nice street setup. About what compression ratio will this yield?

Looking at the big difference in compression height (2.2 being taller but with a very similar dome profile), will I have to shim the cylinders more to avoid these 2.2T pistons hitting the 2.4T heads? With the taller compression height of the 2.2's what about valve / piston interference? Timing chain length issues?

How much will I have to shim them if I do? Just stack shims?

Wayne mentions 2.2S pistons in a 2.4 as one of his "favorite motors" but doesn't provide any details that I have been able to find.

If anyone has done this please send a little advice.

I am trying to figure out if it will be worth the hassle. http://forums.pelicanparts.com/uploa...1105711088.jpg http://forums.pelicanparts.com/uploa...1105711100.jpg

The compression height does not take the dome into consideration. So all the 2.2 and 2.4 pistons all have the same compression height. So none of the 2.2 or 2.4 pistons should hit the head. The valves are a different story though. Definitely check all clearances.

A 2.2T piston has about the same displaced volume as a 2.4S piston. So a 2.2T piston in a 2.4 will give a CR about 8.5, maybe just a little higher. That combo with an E cam will rock!

I replaced my 2.4L T pistons with 2.2L T pistons. No other changes. Look at the piston dome: yes, it is taller, but the valve reliefs are also deeper.

If you upgrade to E cams, you cannot use T pistons (without mods). There is not enough valve relief in a T pistons for E cams. Cams and pistons should match (T, E, or S) to have proper clearances between the piston and the valve.

That is good advice to follow, but you can sometimes get away with mixing and matching. For example, E pistons with 'S' cams will be an extremely close fit...

-Wayne

What Jay says makes perfect sense and is the safest route. What Wayne said is what I was wondering.

I guess I will have to set it up and check it out. Perhaps I can check cam lifts etc in Anderson's book. I may try to initially measure with the head off using the top of the cylinder as a measurement datum. On second thought that won't work, it is all about timing.

What kind of valve to piston clearance is required? I was going to use the clay method unless someone has a better alternative. I am a bit hesitant to try even that with a good valve for fear of bending it.

Does anyone have a couple of worn out valves they could spare for me to use for valve / piston clearance checking?

Thanks,

Bill

You won't be able to just look it up in a book. Remember. you likely will be machining other parts too like the head, so clearances might get tighter than an engine which has never been rebuilt. The clay method is probably the best you have to go with, but some experts might have other tricks up their sleeve. I would try it a couple of times to make sure your investigation is sound, and your measurements repeat. I believe Tyson Schmidt used E pistons with S cams, and machined the valve reliefs in the piston further. Search for 'Tyson Schmidt' and 'scruffy'. The required clearances should be found in Wayne's book.

I am running 2.2E pistons in a 2.4E and this engine rocks!

esses,

Can you quantify that in any way?

It seems 2.2T pistons are not going to work without major pocket milling. I haven't been searching for 2.2E pistons. Got an extra set? ;-)

Anyone have a worn out intake & exhaust valve to spare?

How about the angles at which the valves are set into the heads?

I do not have data as fat as clearances, etc. but from experience my mechanic said that we would have no valve clearance problem. He was right.

I have a real 2.4E with 2.2E pistons. We compared the original 2.4E pistons to 2.2T pistons and 2.2E pistons. The 2.2T pistons would also yield a higher compression than my 2.4E pistons, but lower than the 2.2E. I could not find any 2.2S pistons. With the 2.2E pistons I am supposed to be in the 9.1:1 compression ratio.

I had never driven the 2.4E in stock configuration, but with the 2.2E pistons and Webers (MFI will go on in future), this engine comes on real strong from low rpms all the way upto redline. It has mucho, mucho torque. Unbelievable for a "small" displacement engine.

My guess is that I should be in the area of a 2.4S in terms of power output. The 2.4S has 190hp with 8.5:1 compression. The S cams have more top end power, but I make up for that in torque. My guess is 180-185 ish hp, maybe 190? Any 2.4S cars out there that want to do a side by side test?

2.2E pistons are highly sought after for this mod. You may consider 2.2T pistons. Check them out! Push a piston pin in them and stick your 2.4T pistons on the other end. You won't believe the gain in piston height.

MN

camgrinder from this board has assured me that a reground e cam has .08 mm greater lobe height than a t cam. Thats less than 1/10th of a mm. Whats that a human hair, sliver of paper? He further suggests that many people have put the e cam in the 2.2T engine with good results. Can someone else confirm or deny that this will work before I make a HUGE mistake?

michael

Oh yeah I forgot to mention that the 2.2 T engine will have a 2.4/2.7 std/std crank in it !
michael

Page 189 of Anderson's book says Exhaust lift of a T cam is .345", for an E cam .393, that is 1.2 mm difference so I dont know.

I just compared the valve pocket depths ad follows as measured on the valve angle at the outer edge of the pistons. It bears mentioing that all 6 of my 2.2T pistons showed evidence of valve contact at the outer edge of the exhaust valve pocket:

Intake Exhaust
2.2T 3.3 2.1
2.4T 2.99 2.16
2.4E 4.67 4.88

I don't know about Porsches but most motors that have pistons hit valves because of insufficient clearance when the cams are timed correctly hit the exhaust valves.

=( I just went out the garage and put a dial guage on the e , then the t cam. Looks like about 1.2 mm difference. =( So can I machine the T pistons' valve reliefe pockets? Or just get used E pistons? uuuggghhh.

Michael

Here is a quoted reply from Wayne concerning my e cam t piston dilemma...
So I will press on with the hope that all I will need to do is mill extra exhaust pockets.

michael

Me too. Now all I need to know is the angle at which the valves are set in the heads. I can probably do it myself, er, I mean at my buddies machines shop with him looking over my shoulder.

have a gander... dyno at the bottom.

http://forums.pelicanparts.com/porsche-911-technical-forum/178647-2-2-e-stroker-hp-output.html

matt