Questions on pistons

[Kirkamus]

Ok well I have made a few post about everything I have dealt with in my Gsx adventure but it has not ended yet. Engine is being tore down once again due to faulty machine work so this rebuild is being done under warranty. Well Im wondering about which pistons to go with in the long run. Im gonna be switching to a holset in the future but currently using my e16g to do the break in. Would love input on this.

Bolt-on Modifications:
big evo 16g
3inch full srs exhaust with cat welded in
fmic short route

Engine Management:
ecm link woot woot

Engine Internals:
2.0L bored
1mm osized valves ported head 272 bc cams
Manly H connecting rods

Drivetrain Modifications:
stage 3 John sheppard Transmission
act 2600

Suspension Modifications:
lowered 1 1/4th inch front lowered 1 1/2 inch in rear ebach with kyb-gr2

 

[BogusSVO]

Well what is your goal? HP?

What CR do you want?

What was the last set of pistons? Brand? part number?

What was the piston to deck clearance?

What HG will you run?

What was the failure of the last engine?

 

[cyhm]

Wiseco seems to be the dsm standard as far as I'm concerned. It's all up to you the bore and compression you decide to run, depending on your own personal goals.

 

[Kirkamus]

The failure was due to piston slap on previous rebuild which I told him didn't sound right. Port 3 and 4 of the exhaust manifold were flooded with oil and making it look like the turbo was blown. The last pistons were Manley .020 over but as far as part I'm unsure. As far as hp Long term I'm wanting 450-500ish to the wheels its going to be daily driver so not to extreme.
The cr is actually what I was looking for on input.
As far as clearance I'm unsure what it was but he suggest before the error that we knurl the pistons to remove any chance of an issue so we did. And now He is paying for the rebuild minus cost of new pistons which I Graciously offered to purchase.


Now I do have some fic 850's sitting aside for when I make my switch to holset which may hafta be upgraded down the road as well.



Engine failed after 1502 miles into it. Right before I went to get it tuned so go figure

 

[cyhm]

Oil in the exhaust manifold sounds like bad valve seals, which may be irrelevant.

Headgasket choice and clearances are a big deciding factor in the compression pistons you choose as well.

 

[BogusSVO]

Knurl the pistons... damn talk about old school machining!!

Do you even know what that will do to the pistons? The machinist wants to knurl the new pistons????

Wow!!

I, personally, would ask the machinist for a 2 spec sheets before you even go any further.

One on the piston diameter.

The 2nd should be on the block bores, Top, Mid and bottom, on both the X and Y axis of the block for a total of 6 points per cylinder

Then do the math and see what the PTW was, or if a piston collapsed and caused the slap.

Also, if you are going to foot the bill on new pistons, have him machine the block .040/1mm or have him get a new block to go .020/.50mm

But, and this is just me, I would not want to knurl a new set of $500+ pistons to fit a sloppy block.

 

[Kirkamus]

Sorry to confuse. He knurled the old pistons and it still had far to much clearance to me. He told me they would clap between shifting gears but that is all I should hear of it. That was not the case. He said alot of race cars have it loose. I told him I dont own a race car . Then this all happened.

Head was completely redone at the same time as the block. New Seals and guides due to the 1mm osized valves.

Apon the first rebuild we did get a used block that was good and that was where this has happened from.
Im waiting to get specs of the engine block before personally ordering the new pistons.



ps glad you are posting bogus ALWAYS wise to what you say

 

[BogusSVO]

How much clearance did you have on the knurled pistons?

Same guy do the valve job too? Did he throat cut and bowl blend for the +1mm valves?

If he did not, then you flow the same as a STD valve, or maybe worse if he left the shroud....

 

[Kirkamus]

I will hafta find out from him tomorrow