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Alright guys I’m splitting hairs and bitting my nails the last few days on this rebuild. Absolutely nothing wants to go right. I assemble the short block and what do you know! My pistons are sticking out an entire millimeter! I’ve called yota1 LCE and yota shop. Have gotten different answers from all of them. I had the pistons ground down 0.020” and am going with a 0.040 head gasket leading to hopefully a zeroed out quench! Any ideas? problems? Advice? Has anyone else had this problem?
it looks like you have efi parts for a 22re, so i'm guessing that it's a 22re block, did the machine shop deck the block height?
did you measure the head cc's and calculate the compression ratio?
stock rods or aftermarket rods?
it’s a stock 22RTE no conversion. I’m doing all the math now and with the increase of compression and also accounting for the added headgasket thickness AND the overbore I’m coming out to about 7.27:1 compression instead of the 7.5:1 stock compression which isn’t bad I don’t think.
i had no idea that these engines had negative deck heights, weird... your c.r. should be fine for a turbo in particular, you did actually measure the head cc, right? don't wanna guess at it.
i had no idea that these engines had negative deck heights, weird... your c.r. should be fine for a turbo in particular, you did actually measure the head cc, right? don't wanna guess at it.
THIS IS A BIT OF A FIREHOSE SO BE PREPARED FEEL FREE TO CORRECT ME AS WELL.
they don’t usually, I’m getting a lot of different information from different sources. My machine shop says their spec sheet says 0.020-0.030 out of the block is okay because of stock headgasket thickness. Yota specific business haven’t confirmed that so I’m going with what they know sense they build thousands of these engines. I called Joe at yota1 whose a great guy and has helped me more than anyone with resolving this issue and what I’ve compiled it this:
Negative quench(piston out of block) =not great
positive quench(piston in block) = better but also not super great
*if you’re deciding between shim and thicker headgasket go headgasket*
you want it as flush as possible but this is real life and we’re putting engines together with a 500$ budget in our garages it’s not gonna be perfect.
this is what I recommend after talking to yota shops up and down the coast.
if you have the pistons sticking out of the block measure with a micrometer depth dial. If it’s 0.040” or 1mm get a 0.040+ MLS headgasket if it’s more mill the pistons if it’s less get a less thick headgasket.
I’m new to building engines and what I’ve come to realize is there’s a lot of forces you have to equalize that rely on each other and as long as you’re accounting for that and you’re landing in a specified ballpark (like think within two decimal places) you’re gonna be fine.
better safe to have a positive quench than sorry and have an overly neg quench and blow your head off.
cheers.
Last edited by Carloxaugustine; 06-26-2024 at 11:46 AM.
milling the top off of a piston decreases compression, because it effectively lowers the piston in the bore, which increases the overall space for combustion... what happens with aftermarket pistons is that you can get different pin heights, which can include the equivalent of milling the top of the piston, aka lowering the compression ratio.
you must know the total volume of the head chamber to calculate compression ratio, see the video below how to measure it, and how to calculate the compression ratio... if the head has been milled, if the top of the block is milled, etc., those things change the compression ratio, how close the valves are to the top of the piston, etc.
the question that i would ask is, what's the factory deck height and gasket thickness, for a turbo motor?
06-25-2024, 08:21 PM
