3.2 Piston Options, High Compression?

[JackMan]

I tore down my engine yesterday, 116,000 well cared for and thoroughly documented -- all receipts back to mile 1 - car and engine. I'm the third owner. I have KS Alusil pistons and cylinders, 95mm, with stock compression of 9.3:1?. We measured the pistons and cylinders and I could use them again if I choose. The tranny shifts just fine and I'm gonna leave it alone. I do not have a limited slip. I'm not opting for gear work as the car is a daily driver, otherwise I'd regear the gearbox or the final drive unit.

I am having cam reprofiling and head port/polish work done to the engine along with a host of other refreshing service items: refresh the rockers, rebuild clutch, you name it.

I have an autothority chip in the car.

The car is my daily driver in good weather. Last year I upgraded the suspension and brakes and did a thorough service of all suspension and drivetrain components. I also back dated the exhaust to pre 1974.

I would like to recoat the cylinders and install JE 10.5 95mm pistons. I am told I will have issues with detonation if I do this as the ROW car I have has a different ECU that the Euro version that came with the 10.3:1 Mahle pistons.

Please provide me with your feedback/recommendations on the following

1. Using the current KS pistons and cylinders. Just rering them and be done with it.
2. Recoating the cylinders and installing new 95mm JE 9.5:1 pistons.
3. Recoating the cylinders and installing new 98mm -- taking displacemnt to 3.4 lts -- JE 9.5:1 pistons.
4. Recoating the cylinders and installing new 95mm JE 10.5:1 pistons.
5. Recoating the cylinders and installing new 98mm-- taking displacemnt to 3.4 lts -- JE10.5:1 pistons.

Or

6. Just fork out the bucks and get a set of Mahle 3.2 liter 95mm 10.3:1 Euro Specs pistons/cylinders.

The cost to do the recoat and the 95mm JE 9.5 or 10.5 pistons is $2,000.

The cost to do the recoat and the 98mm JE 9.5 or 10.5 pistons is about $2,800. (Have to rebore the cylinders to 98mm pistons size before the coating.)

The cost to buy the Mahles 3.2 10.3:1 is about $3,500.

The cost to reuse the existing pistons and cylinders is cheap. Just rings.

Any ideas on power, wear, etc.

Please help.

Thanks

Wellborn

[Jeff Alton]

Lets see how I do here....

1. You can reuse them but it may be difficult to get the new rings to seat. I have had luck getting the KS stuff honed with the Sunnen 3 step process recommended by KS

2,3,4,5 If you are going to get new pistons and have the cylinders "worked" may as well get 98's and have a 3.4. 10.5 will require twin plugs. Don't be fooled by Mahles inability to state accurate CR numbers. They have a rep for being way overstated....

6+ Mahle makes a great product and many will say that is what you should use. That said, lots of folks have used JE with good results. I have a set 10.5 98's on my shelf now that I will be using this winter. I think you can get the 98's and the cylinders bored/plated for closer to 2k from EBS in Nevada.

Used pistons are already worn to some degree, so I would expect that any new p/c set will outlast what you have now. For ultimate longevity, go with the Mahles....

There is a great thread here on honing, it starts out about nikasil but there is plenty of info about the KS stuff as well on it. Search my user name or "do I need to hone this" and you should find it pretty quickly.


Hope this helps a little

[ChrisBennet]

Originally posted by JackMan
I am having cam reprofiling and head port/polish work done to the engine along with a host of other refreshing service items: refresh the rockers, rebuild clutch, you name it.

I would question the advisability of "porting and polishing" the heads. According to one source I read (Greg Brown) the stock 3.2 head will flow enough for 300 hp - something you're never going to get near with that restrictive backdated exhaust.

I'm all for building up a motor because it's fun (and life it too short not to have fun) but if you are looking for at HP/$, upgrading to a 3.6 is more cost effective.
-Chris

[JackMan]

Thanks for the advice.

I've decided to go with the stock compression JE's at 98mm. EBS says they will bore and recoat my cylinders.

wj

[ChrisBennet]

Originally posted by JackMan
Thanks for the advice.

I've decided to go with the stock compression JE's at 98mm. EBS says they will bore and recoat my cylinders.

wj

Just a heads up: Make sure you measure the compression. The last 2 sets of "9.5:1" JE's I got CC'd out to 10.5:1. EBS is great but you must still measure everything.
-Chris