so i overheated the engine on my srt so i get to rebiuld it with better internals. i found some oversized pistons on modernperformance. i was just wondering they have 2 different compression ratios 8.0:1 and 8.5:1 what on would be better for a stock turbo. i know the stock compression ratio is 8.1:1. o and i was wondering when i put in oversized pistons if i will have to change anything else. im getting a replacement head cause mines warped and im wondering if ill need new cam shafts or anything like that head or timing related. also i saw on there site they sell underdrive pullies too. i bought one of these years ago and never installed it cause i read some where that they can cause oil pump failure. i dont know but i would think if there is two different companies selling the pullies then they cant be that bad right? i dunno i just want to know for sure before i install it. i hope there are still people reading this forum too. thanks

 

Well if you have to replace the head, get a ported one. And seeing as you have the head off put in some cams. Even with a stock turbo it will help out. Ya dont do the pulley. While you are at it, get a new oil pump, and ditch the balance shaft.

 

how much more do you think a ported head would be over the stock replacement i found one for $320 shipped and where is a good place to get one. ive been on modernperformance, any other good sites? also any suggestions on cams i see there are three different stages of crowler on modern im just wondering if having the cylinders bored .020 over (the only oversized pistons i have found so far) will i need to change cams? yea i thought the pully was a bad idea thats probly why its still in my garage 3 years later. new oil pump for sure sounds like a good idea and ive heard about removing the balance shaft but i forgot all about it till you said that thanks. i knew there are still smart people on here checking this section

 

The stock ratio was 8.5:1 I thought? If you belong to the SRT forums hit up Joe Dirt, he knows where you can get stock pistons but up to .040 over bore for a good price, he can also port your head as well he did mine. Don't really need to get cams just a good idea, if your staying with stock valve train you can only go with stage 2 cams, I have BC s3 with their full valve train set up with +1mm valves on int and ext, course Im no longer have my stck turbo on anymore, but hey even s2 cams help with a power band it hold the hp better.

 

everything ive read said its 8.1:1 but i know how much i trust mag reviews so i dunno. im just wondering if i should go with 8:1 ratio or 8.5:1? ive heard with a turbo engine that you want to keep the compression ratio low but i know on a NA motor the higher the ratio the more power you get so i dunno. i like the pistons ive found cause they are forged aluminium so i can run a little higher boost. how much of a power difference do you think there would be to go .040 over instead of .020? i geuss twice as much. ok so i might go with the cams it sounds like a good idea. i wish i could port my stock head but the tech at the dealership said its warped so im gonna need a new one. where did you get your new head? +1mm valves sounds like a good idea after boring out cylinders. o and have you removed your balance shaft? i know it ads some power but ive read it makes the engine vibrations more just how much more i wonder. i have motor mount inserts and that makes the vibrations a lil more but not enough i care about.

 

Well he had a spare head there that came off his old motor and he ported it out when he was running it. Yes get rid of the balance shafts I did, espcially if you are aiming for higher 300hp, plus they add 10whp just by removeing them. you'll feel a bit more vibration, its not bad and I have AGP solids all around on mine, with .040 you get a little more power due to more surface area that can hold more air/fuel. But if you want the pistons you found cool, I was just throwing it out there, stock pistons are good for around 600hp, they are made by MAHLE or as some know the name as Clevite. Its just a personal choice, .020 over is a good way to clean up the cylinders. +1mm valves helps more flow, again it all depends on what you want. Turbo cars do need low compression due to the air being forced into the cylinders, where as NA need higher comp. cause they need to pull it in. Most aftermarket pistons are 8.5:1 but you can get 8.0:1.

 

im not on srtforums but i geuss i need to be .040 over sounds better to me ill find joe dirt. will the cost of boring be anymore for the larger size? what kind of psi can i run with these pistons do you think? what compression ratio are the pistons in your car 8.5:0? im just looking for personal experience from people on this forum if it works for you it will work for me right? i looked at the head today and it felt flat with a straight edge but i dont know. my next question is how much of a procces will it be to take the block transaxle and all of that out of the car? the tech said the engine needs to be taken out from under the car i have an engine crane is it possible to take it out from the top? ive worked on a few cars but most of them were either older v8s or bigger vehicals this is my first compact car.

 

I have taken just my engine out through the top, the thing I found is have the trans jacket up to the right angle and your clutch wont fall off, mine sat proped up for a few days and it never fell. Through the bottom is how the factory installs them as you can tell, but you dont need to, if you have done it on v8 its just as easy. The cost should be the same on the oversizeing of the pistons, I know a shop here in Mira Loma called dougans does great work, they did all my work on my hot rods engine. I have 8.5:1 CP pistons in mine, works great. If you go with stock pistons or if you have the money call JE they can make you some that are 0.040 over for a price, how much not sure, but the factory ones can handle 25-30psi I believe, they should if they can handle the 600hp mark. When you remove your balance shafts you'll have to plug the oil feed with a self tapping screw, when you join the srtforums there is a how to section and I know for a fact that the balance shaft removeal is there. Forward motion also sell 0.040 pistons for these cars, i think the price was around $4-500, maybe high $300's, they are forged, just some options to check out.

 

just an update i got elbows deep in my engine tonight in case anyone cares. i got everything off of the block and tomarrow i am going to remove the block from the tranny and pull it out. my only question (kinda) was the jackshaft it seems to be above the oil filter and i couldnt get it out of the way so i dunno i think i can get the block around it when it suspended. o and the engine mount on the passanger side i can see it from inside the wheel well and its a huge torx bit do i just unscrew that and the engine is free? after i get the block out then i need to find a shop to bore out the cylinders. im geussing any machine shop that bores out cylinders on the regular would be able to do mine? i really cant wait to get my car back bigger and better

 

you have 3 motor mounts. The one mentioned by the drivers wheel, the upper one passenger side by the valve cover, and a lower longer one under the car behind passenger wheel. Once you disconnect from tranny, that should free it up.....wiring harnesses of course.

Yes, any shop that bores can do it