Need help understanding Spec sheet for pistons

[Ajax]

Guys I am having a brain fart and need help deciphering the sheet. I bought a howell new 2.2 stroker kit from a guy on here and assumed he would get the .040 over pistons that are required for this kit. But getting the parts I looked at the sheet and I believe he only got the .020 over. Also he did not know what compression, how can I tell what compression it is?
Info:
Piston Part # 219445
Piston Type: DISH-Flat Bot
Bore: 3.464

Dish Depth: .020
Comp Dist: 1.100
Int: .120
Exh:.120

 

[DSM_PWR]

Why is .040 required? Does your block need that big of a bore?

Also who makes the pistons?

 

[rstare]

Stock bore is 87.5mm or 3.44"

 

[Ajax]

JE makes the pistons. This is the kit 2.2 Stroker Performance Bottom end Kit - btmendkitstr and it states in the description to achieve the 2.2 displacement it needs to be bored 0.040. And my block already is bored .040. So I have 2 choices get a fresh block bore it .002 but dont achieve the displacement or see if I can find some 0.04 pistons. Anything on the compression yet?

 

[DSM_PWR]

If this was true.. why would they have the option for .020 pistons that just doesnt make sense...

Either way, you cant just get your block bored .040 and put in any off the shelf .040 pistons, what you need to do is give the pistons to your machine shop and have them bore the block specific per piston...

Not all pistons are equal and your not always going to get the same clearance.. which is why most people wonder why they're getting pisotn slap

 

[talon20g]

If this was true.. why would they have the option for .020 pistons that just doesnt make sense...

Either way, you cant just get your block bored .040 and put in any off the shelf .040 pistons, what you need to do is give the pistons to your machine shop and have them bore the block specific per piston...

Not all pistons are equal and your not always going to get the same clearance.. which is why most people wonder why they're getting pisotn slap

I'd hate to think I'd spent $500 to $600 for a set of pistons that were different sizes. If I find a company that just can't seem to get there tolerances right, I might not be buying from them.

If I was you I'd get another block and have it bored .020 over, magnafluxed, cleaned and call it a day. The small bit of difference in the .040 over pistons wouldn't make a noticeable difference.

 

[Ajax]

Yeah I think getting a bare block is prob the best or cheapest option at least. Talked to a shop and he said he might be able to work something out with JE or another customer, but otherwise the used block is prob the way to go. Thanks for the input guys, but how can I figure out what compression they are. Yes and I wrote to Howell asking why the hell they have have stock and 0.02 bore for options!? Ridiculous

 

[Ajax]

Ok got about 2000miles on her and did a compression check. And I am not sure what to think here any input would be great. Did it on a decently warm car. Water temp 185 Oil 160. All 4 plugs removed and throttle wide open. Cranked it over 7 times for each one cylinder.
1-240
2-240
3-239
4-240
Now I know that is really high! What pistons would this be? What issues can I run into with these numbers? Thanks in advance

 

[420aNEWB]

do you have pictures of the pistons so we can see them...?

 

[Ajax]

This is the only picture.

 

[Drifter27_04]

As the pistons originally produced for N/A motors your numbers will be high, as for which pistons you have I can't answer sorry. The only issue I see would be the amount of boost you will be able to run on high compression pistons. If anyone see different please correct me.

I imagine it spools up that PTE 50 pretty quick say?

 

[Ajax]

Havent really turned up the boost yet having issues with my Megasquirt. Keeps cutting/breaking up on higher boost. Diff. question wondering what I should gap my plugs at. From reading the 4g guys do it 0.28 and the 420a guys around 0.44. Did mine at 0.28 but thinking I should open them up a little bit. And on the pistons I will call JE and see if the have some insight on them. THanks

 

[Ajax]

Ok howellautomotive says they are 8:6 but seems pretty low for the compression numbers I got??

 

[rstare]

I would say they're 10.5:1. Stock ratio is 9.6:1, and those compression numbers are supposed to be around 210, IIRC. So, the next step up would be 10.5:1.
However, there's so many variables in a compression test it's hard to say for sure, but that would be my guess.

 

[bullettdsm]

Ryan, while your reasoning is sound, those are not 10.5's. They do look a lot like a set of 8.6's I got out of a Howell engine. If Howell says that they are 8.6's I guess I would believe them. They gave you that number off the part number correct?

Do you have the head shaved any? I agree that those would be mighty righteous numbers for 8.6 comp. What did you do for ring gap?

MB

 

[bluegs03]

wow thats some compression, i can almost guarentee that the reason you are having trouble with megasquirt is ### of that high compression test result. If its indeed 10.5.1 your gonna have to tune that thing completely differently it wont like alot of timing up top. maybe thats why its breaking up?

 

[Ajax]

Another thing that might changed the compression completely is that the kid I bought it from was supposed to buy the .04 over pistons to get the 2.2lt displacement, but instead got the .02. But I still have the 2.2 stroker crank installed. The high compression could also be the reason my MS is breaking up the top since the previous tune was for much lower compression. But this compression is also causing me to loose alot of oil. Changed my oil at 750 miles and then at 2000miles I checked and was almost 3 quarts low. Yes I know I was suppose to check it more often, but I did rack up those miles in about a week. But did not think about checking my dipstick untill I saw some blueish smoke (very little) when I realized I was the 3 qt short! I did check my radiator nothing in there and its not on the floor. So after checking the compression. There are 2 places left to figure out. #1 being my turbo is leaking( no shaft play) or valve seals are leaking(brand new) My oil pressure does seem a little high but its a new motor (+-80psi cold idle) at 1200rpms. Any input. Could also see it being blowby but with that compression numbers I think the rings are seated pretty good.

 

[bullettdsm]

I bought a howell new 2.2 stroker kit from a guy on here

How in the HECKLE AND JECKLE did I miss that?! Damn, reading is FUN-da-mental

Ok, because this is a Howell kit and because you got this off someone else, I'm wondering if those pistons aren't stroker pistons? I'm not sure how Howell sets up their kits but I would presume that they would have to use a stroker piston with the rod and crank combo. The stroker piston generally has a higher position for the wrist pin. So with that being said, I wonder if these pistons are the "standard" 2.0 pistons. That would certainly add on compression (because basically the piston goes up further toward the head with the longer stroke. Thus generating more compression).

Now I haven't looked at their set-up etc. Nor have I done any math with this, BUT it would certainly explain the higher comp.

Also, what I was alluding to on the rings was the thought that the ring gap may have been too small. That could generate NO blow by which would be a problem.

With all that being said, you have what you have for compression (which is above normal 9.6 compression for our engines) and need to work with it. There is a good chance that you need to back off timing. With my 10.5 comp engine, I'm running 13 degrees (now that's on a BW366 @30lbs) and I'm having a problem with blowing out spark (my spark plug gap is .016 and I am using the Screamin Demon coil). So you may want to back off your timing a bit.

MB

 

[Ajax]

Thanks bullet for the insight. I will def back some timing off but I am running on E85. You have you spark gapped that small? Mine was .28 but people suggested it should be .44 so I opened it up a little. But didnt make any difference I guess it will not hurt going the other way. But I have to figure the oil thing out first. But busy working on the house before the snow flys. But will keep you guys updated.

 

[bullettdsm]

You have you spark gapped that small? Mine was .28 but people suggested it should be .44 so I opened it up a little.

The .044 number is for NA. I gap my 12.5 comp NA to .041-.038 depending on certain conditions.

Yeah, you should start at .028 and work your way down for turbo. With the higher comp numbers you have, you may want to start lower. At one time, with the stock coil, I had her down to .014.

MB