rebuild for forced induction.

hybrid-Srt2001 · Post by **hybrid-Srt2001** » Thu Aug 02, 2007 2:50 pm

so i'm rebuilding the acr to handle some more power. my question is... I know that i need some better rods, because i've seen alot of them break on others' cars, but do i also need forged pistons, or will stock be ok. the car has 119,000 miles on it, so should i bore it .20 over or leave it

OB · Post by OB » Thu Aug 02, 2007 3:37 pm

The more you spend on forged internals, the more reliable the engine will be with boost. Forged pistons are a good idea, especially if youre planning on swapping in upgraded rods anyway. Boring isnt necessary and might actually be more trouble than its worth in HP gains, but if you want to get into detail in squeezing every last pony out of the engine, then its something to consider.

hybrid-Srt2001 · Post by **hybrid-Srt2001** » Thu Aug 02, 2007 3:44 pm

thanks OB! i was just hoping to save a little money. do you know where i can get a good price on some JE pistons? and do you think stock c/r will be alright. i need to be able to pull the turbo every 2 years to pass smog, and dont want it to be a total slug w/o the turbo.

OB · Post by OB » Thu Aug 02, 2007 3:49 pm

It really all depends on how much boost you plan on using. Turbo size and surrounding components (intercooler, wastegate, etc) come into play a bit as well. You're 01's C/R is 9.8:1, which is a hair high for a high performance forced induction setup, but perfectly safe if you only plan on running a few lbs of boost. The never ending compression vs turbo debate will always be there, but it is a fact that a lower compression engine is safer (reliable), and some even say easier to tune. The other people claim that slightly higher compression will help spool the turbo faster at lower revs, but common sense tells us that this comes with a tradeoff of lowered reliability (due to increased chance of detonation from higher combustion temps) and requires a more precise tune.

hybrid-Srt2001 · Post by **hybrid-Srt2001** » Thu Aug 02, 2007 3:56 pm

yeah i kinda figured as much. i dont plan on running more than like 8 lbs max. i will be using an srt turbofold and the portfueler. i guess i can always get an head-shim when i decide to have the head ported...

OB · Post by OB » Thu Aug 02, 2007 4:03 pm

I wouldnt suggest the shim, that's a bit of a band aid fix IMO. If compression is an issue, do it right and swap the pistons and rods out. On 8 lbs or less, you should be ok with the stock internals for awhile, but if you constantly beat on it then that life expectancy goes down quick. It would be wise to spend some time freshening the motor up (bearings, seals, gaskets, studs) to protect your investment. However, by the time you spent the money on forged internals and all the stuff needed to make things work, you might as well have bought an srt-4 motor. Thats the main debate for me right now, srt swap or NA. Building the turbo 2.0 has been out of the question ever since I realized how silly it would be to spend all that time and money when an srt motor could be had for about an extra 500-1000 and make more reliable power with zero mods.

hybrid-Srt2001 · Post by **hybrid-Srt2001** » Thu Aug 02, 2007 4:36 pm

yeah i'm rebuilding the entire motor with bearings seals and the works. it's grambo's old acr, and it had rod knock caused by oil starved bearings. i'm going to get the crank turned 10 under since it's not too bad, and do the internals.

Jamie · Post by **Jamie** » Thu Aug 02, 2007 6:45 pm

it sounds like your on the right track. personally if your having the crank machined then i would go ahead and get the cylinders bored out to a good 0.020 over just to clean them back up and get them back round again. Plus when i was looking for pistons in 8.8 to 1 it was easier to find them in the "20 over" then it was to find them with the stock bore.

Its like OB said, the debate over compression on turbos will far surpass my lifetime im sure however in my experiance with my vehicle the tiny bit of lower end power that i lost compared to the outragous mid and top end gain that i recieved by being able to boost it up to about 14psi (spike at 16) SAFELY... is well worth the forged internals.

so IMHO get your crank polished

get a good cleanup bore on the engine and throw some JE turbo pistons with an 8.whatever you want compression ratio. some eagle H beam connecting rods, or some crower connecting rods and boost to your little hearts content!

Happy Boosting
J

esteinmaier · Post by **esteinmaier** » Thu Aug 02, 2007 7:30 pm

With that many miles, it's going to need a cleanup bore. If you are going to run pump gas, I'd recommend the lower compression, but if you are going to run race gas or e85, feel free to do stock compression.