OST and JE Piston collaborate - New piston!
08-15-2014, 05:47 PM
Post: #11
OST and JE Piston collaborate - New piston!
One last bit.... the crown can be machined as much as .030" (.76mm). This will remove .9cc from the crown, dropping total crown volume down to 1.6cc. This will lower static compression by about 1/4 of a point.

So in an undecked block, under a 36cc chamber running a stock head gasket... these pistons can offer a static CR as low as 10.6 to 1. At the other extreme, with a decked block, small - 33cc -chambers, a stock gasket, and full crown(2.5cc) these pistons will deliver a static compression of 11.8 to 1.

Dan -

You can |Sad .... OR you can ask for help!!!

OST Porting service - http://hachiroku.net/forums/showthread.php?t=19991
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08-26-2014, 06:01 PM
Post: #12
OST and JE Piston collaborate - New piston!
UPDATE.......

I recently showed this thread to a racer friend of mine and he wasn't kind... asking me if I wanted my friends engines to perform less then perfectly(blow up)... I felt a little shocked, and pretty embarrassed (a bit angry too) and so I asked him what he meant....

oldeskewltoy Wrote:[Image: AEU86 AE86 - OST and JE Piston collabora...ew piston!]


this set of OST/JE pistons is ready for fitment


He then handed me a STOCK 4AGE piston and asked me to find it on my own..... (ignore the black, look for red)

[Image: AEU86 AE86 - OST and JE Piston collabora...ew piston!]


Not just MY pistons... but ALL aftermarket 4AG pistons suffer from this. Heat LOVES a sharp edge... a simple radius around the valve reliefs will not allow the heat to focus on a flaw and burn the piston.

So... for ALL aftermarket piston users... have your machine shop add a 1/4 round around the valve reliefs and your pistons will survive far longer under SEVERE loads.

Dan -

You can |Sad .... OR you can ask for help!!!

OST Porting service - http://hachiroku.net/forums/showthread.php?t=19991
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08-26-2014, 10:46 PM
Post: #13
OST and JE Piston collaborate - New piston!
from another forum Wrote:Confused. I dont see how the red area having an extremely large 1/4inch round is going to make or break here... Sure, it's good and nice to have everything be unsharp...

I was debating with myself if it was necessary to include an amount. My apologies... the 1/4 round he was speaking of was somewhere between .030" and .040" (.75mm to 1mm). The stock piston is closer to .065" to .070" (1.6mm to 1.8mm). Much less than .030" isn't much of a 1/4 round. The photo was a bit of an exaggeration, but it was to offer a visual description.



from the same forum Wrote:His friend was probably exaggerating a little to get his point across


The point being almost all custom pistons need a little work for best results

we as customers are thinking hey for that much money they better be ready to go but for a lot of items it just don't work that way

My friend knows that I've been hanging back (part development) in the 4AG world for a long time... he knows I want as perfect a part as I can possibly deliver... so he was digging at me for saying the piston above was ready.... when in his mind (and mine) it should have gotten more of a radius...

My embarrassment is everyone else's "free" lesson.


His was one of a few observation on the FSR skirts that caused me to have these built with full skirts.

Dan -

You can |Sad .... OR you can ask for help!!!

OST Porting service - http://hachiroku.net/forums/showthread.php?t=19991
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01-13-2015, 11:33 PM
Post: #14
OST and JE Piston collaborate - New piston!
Good news... Bad news.....

Good news, these pistons are basically fully customize-able now. Custom bore, custom compression height, any wrist pin you want....

Now the bad news... I can no longer sustain the price... cost now is $750.00 per set, PLUS freight

Dan -

You can |Sad .... OR you can ask for help!!!

OST Porting service - http://hachiroku.net/forums/showthread.php?t=19991
Find all posts by this user


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