I ordered 1 stock CL-S piston and it came in today. The first thing I noticed is that
it hardly has a dome! The dome is about 1mm taller than the rest of the piston surface. Secondly there is anti-friction coating on the skirt - on the two sides that actually would get close to the cylinder-wall. The other sides are where the wrist-pin goes and that is at least a 1/2" from the edge.

There are two compression rings and an oil-ring. These are cast, but the finish is very nice. There are no sharp edgs on the piston surface (prevents hot-spots). Not sure how much a flat piston would reduce compression by... maybe a 1mm dish would do the trick - anybody know the combustion chamber volume?

FYI Part #: 13101-PGE-A010
Price: $26 and includes the wrist-pin and clip(s)

I am going to gives these to JE to do some measurements and order a set of 9.5:1 compression pistons (or 9.0:1, I have not decided yet).

 

nice work Ram.

 

^^bump

Thinjim etc. anybody measure the combustion-chamber volume??

 

Never mind... 3.26 in^3

The 2003 manual says 3.27 in^3

Bore is 89.0
Stroke is 86.0
Bore-spacing is 98.0 (that means the width of two cylinder walls is 9mm - kinda small!)

 

Well the CL-P doesn't have domed pistons and it has a 9.8:1 compression ratio vs. the type-s' 10.5:1. You'd probably need a 1mm dish to get to a 9:1 compression ratio.

 

This is gonna get good. I'm just gonna sit back and watch.

 

Well, there is another spec. for minimum combustion chamber volume which says:

J32A1: 3.71in^3
J32A2: 3.44in^3

Now, they also state that the cylinder head volume is 3.26IN^3 for both heads. This means that the combustion chamber volume difference is solely attributed to the dome-size difference between the two pistons (given that the bore and stroke are identical).

So... there is a 0.37in^3 volume difference introduced by the piston. It appears that the dome is about 1mm tall, say 87mm wide (87mm because it is curved on the edges and I don't want to calculate all that)... and about a tad over 1.4" wide. So, 1.4" x (87mm / 25.4) x (1.5mm / 25.4) ~= 0.3in^3. The dome height is more like 1.5mm instead of 1mm. So, to a first order, I can estimate that a flat dome (given the J32A1 compression-ratio) is 9.8:1. Now, a 1.5mm dish given the same constraints will reduce it 0.7:1 further, yielding 9.1:1. I might just go for a 1mm dish which should put it right around 9.5:1.

I am just trying to prove to myself what Mclaren just stated.

 

I was just guesstimating based on what you said the dome height to be, but if you say so

 

I think you guestimated pretty well!

 

the calculations seem right. doing this though will mean that you have to stay boosted for quite some time! GOOD!!

 

[QUOTE=allmotor_2000]
FYI Part #: 13101-PGE-A010
Price: $26 and includes the wrist-pin and clip(s)
[QUOTE]

where did you find it for that price? www.acuraautomotiveparts.org wants 56.52 minus the rings

 

correction the part number is 13010-PGE-A01

 

yes, I have the combustion chamber volume, but it is not here at my home. I'll post the chamber volume later tonite.

 

So since you are giving the factory piston to JE, basically that leaves the door open to them to design different pistons for other internal engine modifications, i.e., 3.5L crank+rods+custom pistons, or higher compression pistons for a standard 3.2L engine, etc?

 

That would be pretty sweet....!!

 

 

Yup, they can make anything I suppose. Does anybody want a 11.0:1 set ?? If I order multiple sets it will be much cheapter - I'd say $750 or less for the set (including rings).

PM me because I am going to talk to them on Saturday.

Also, the part # does have that extra '0' at the end - at least my box says so!

 

what kind of gains would we see from 11.0:1 compression?

 

With 11.0:1 or 11.5:1, some intake-manifold work and possibly head-work + cams, you are looking at 350-380hp at the crank quite easily.

I'd venture to say with 11.0:1 or higher pistons along with a balanced and blue-printed botton-end, you could achieve 320whp NA.

 

I'll have a stock upper intake manifold available in the coming weeks once the IC is installed. I'll offer it for free, with a deposit that will be returned upon the delivery another stock upper intake. This will provide little to no down time while one is being worked on.

 

are you still looking for the cc of the 3.2 heads?

 

Why an 11.0:1 set? I thought you were going for a low compression ratio.

I don't see how it would be cheaper if the pistons are gonna be different (9.5 vs 11).

<----confused

 

On the same vein as this thread -- has anyone ever gone to Comptech to see if they're interested in doing any of the internal upgrades on the J32A2? According to their site, they supposedly will do staged engine upgrades for B, K, and J block series Honda engines with forged components, cam upgrades, porting, etc?
http://www.comptechusa.com/machine.html

 

Lower compression = more boost can be run safely.

Higher compression = more power for N/A applications.

 

I know that, but I thought he was ordering a low compression set, so why would people buying a 11.0:1 set lower the price since the pistons will be different.

 

he's trying to help out the FI, and NA guys of course

 

what can this do for for us n/a guys

 

I'd assume that since the pistons have the same dimensions regardless of the top of the piston (dish, flat top, dome, etc) it would be easier to fab something up if it was all done at the same time.

 

Increased compression = more power. How do you think Honda squeezed 240 hp from a 2 liter 4 cylinder engine in the S2K? 11.5:1 compression ratio

 

what is the j32 engine maximum bore capability?

 

dunno maybe 0.25" oversize on stock sleeves

 

so if that was a possibility what would that eqate to in engine size?

 

Dunno if I'd go that much, maybe 0.10 at the most. Just look at the spacing between cylnders.

here's something for ya. A 3.5 turbo in the making.

block sleeved by AEBS


main cap studs


stock 3.5 piston with valves from 3.2. working on cc'n the head.



stock forged steel 3.5 rod with new pauter rod

 

Looks sweet.

 

Dean has a set of pistons still for sale, and CHEAP!


https://acurazine.com/forums/car-parts-sale-361/custom-pistons-sale-155098/

 

Jonesi you have a PM

 

Can't see the pics Host them with something else.

 

Pics work fine for me.

 

$550 is a very good price - there is no way even if I order two sets from JE, they will go that deep. I have asked Dean for a picture and if they appear suitable, I'll buy one of his sets.

 

To use Dean's pistons, what else would you need other than MDX crank and rods?