hey i am building up a spare block.. and i want to get it bored and all the machine work and shit.. then im ganna put it in my car.. will the car run fine with 8.6:1 compression until i get a turbo? will i loose any power? or even gain any? let me know.. also the motor will get broken in well until turbo if i do that too and i can put stage 2 on and boost 15 psi right away with afc and injectors
tia

1997 Mitsubishi Eclipse GS
My other ride is your girlfriend.

yes it will run good, and no, will will actually loose power with lower compression.

if you are going to run n/a for a while before a turbo, may i suggest running 10.5:1 compression, and when you turbo just run 10-12 lbs instead of 15. that way you can actually gain hp while n/a and still have a strong bottom end when you are ready to turbo.

mark

stage 2 turbo and all that crap

yeah what he said^^

1998 dodge avenger 4 cyl AT
Mods are:
Not enough

the thing is though.. i want to run about 15psi daily.. and like 20-25 at the track.. what if i want to use nitrous also? i think i need 8.6:1 compression pistons because i know i want to make a blown out beast... so i think the best thing for me is the 8.6:1.. i doubt iill loose that much power if i do that until turbo.. if anything ill gain some torque cause of the bore.. also how much does the rebuild kit cost?
tia

1997 Mitsubishi Eclipse GS
My other ride is your girlfriend.

you should read the post by gary at howell about compression and turbos. going to the 8.6 you will lose approx 4% HP the .020 extra bore isn't gonna do much if any. all the real drag racers are finding that they can do much better running high compression and a little lower boost. The phatridez neon is running 11 compression with 30 lbs of boost. but its all up to you, but some guys here on the board are running 10.5 with no problems and are running 15-20 lbs of boost. check out kiku's post about his carlisle dyno session he will be hitting 300hp very soon and would have been without some leaks and he is running 10.5 with no problems and he claims that car just screams now.

1998 dodge avenger 4 cyl AT
Mods are:
Not enough

Well the compression choice is yours, 8.6 will give you more room for error on your part in tuning, where 10.5 and higher will not. Personally i would rather go higher compression and skip the boring out, cause you'll save some cash. since the the price of the rebuild kit will be the same weather you go hi or low comp.
If you go lower comp and do lose the 4% its only like 5hp at the crank since your basically stock. And you'll only gain about 5hp if you go higher (since you n/a) now that 4% will increase as you add more power i.e. turbo. so somthing to consider.
I plan to run around 18 daily with my 10.5 compression. and eventually run some nos, but how well i'll have to keep it tuned is somthing i'll find out as i go.
Dino and a few others are having great success with lower compression, so you can get an idea of how your car will be.

I'd say save the $ that is costs to bore and get a step up on the compression. you could even get 9.5:1 from howell and be almost stock in comp.

Almost all of the houston crew are running the low comp set up. This is a big theory on how you set your block up in regards to the turbo exhaust and all. I ran the low comp all motor till i added my turbo. The car ran slow as shit and when i put the turbo on Its changed drastically. I however am running around 9psi of boost at over 300hp. So it doesnt all depend on the block. Consider this your bolck is just a big air pump. The better the flow , the more the flow, the more forced induction and bla bla bla. So to answer the original question will my car run good yes bottom line about a half second faster. late mike

stage BIG custom mj racing turbo set up, built block.worked head,all tial components, hks evcez,spearco 992,oh yeah and a huge bottle in the trunk last run all turbo 13.8@108 no nos dyno'd at AEBS in Cali with 300+ hp to the wheels

all in all the car with the 12.5 running 10lbs will be much faster than a car running 8.6 and 10lbs of boost. but its harded to tune a higher comp car but the results are worth it.

1998 dodge avenger 4 cyl AT
Mods are:
Not enough

When I blow a silicone connector off or somethring, my car would be spanked by a geo metro.... so i dont know what your thinking.. It runs fine, its just so god damn slow... but yeah, i'd reather have lower comp pistons cause I am not a master tuner, i need some margain for error.

if you blowing silicone hoses off? the pipes arent beaded? or are you running those elbos? I havent blown my pipes off yet. Took it up to 20 and all is intact. late mike

stage BIG custom mj racing turbo set up, built block.worked head,all tial components, hks evcez,spearco 992,oh yeah and a huge bottle in the trunk last run all turbo 13.8@108 no nos dyno'd at AEBS in Cali with 300+ hp to the wheels

What you have to remember about running boost with compression that high is that you'll always have to be running the highest octane available from the pump and to turn the boost past 10 psi you'd need race gas. I think that would be a pain in the butt. You would get faster spool-up definitely but with the ceramic ball-bearing turbos and what not out right now that can be ignored. One thing that you'd also worry about is just how good you think you are with tuning. With 10.5:1 compression and 10-12 psi, knock and detonation would be a constant threat. And I don't know about everybody else, but here in Houston money doesn't grow on trees and I don't think anyone would want to rebuild... again... after blowing another motor because their gas wasn't good enough. That's just my thoughts, I'd stick to 8.6 or maybe 9.

Luke

1998 Mustang GT 5-speed
2002 Lone Star Shelby Cobra Replica

While i was breaking in the motor, for the first 3500 miles, i wasn't turbo. I thought it had more power than stock (i also built up the head)
I would like to put a vote in for the lower compression, higher boost. What kind of racing do you plan on doing? Drag.. AutoX ??

Drag.. i'ld think that lower compression would give u much more power, look at GT cars, they are running 6.0:1 compression and
75 psi of boost, and what 1000 hp out of a 2.0 liter? If you go 8.6:1 you can run up to 35 psi with the right mods.

Auto X.. higher compression would be better, you want low turbo lag, so you want higher compression which builds the exuast gasses
faster, therefore spools the turbo faster.



97' Eclipse RS (kinda)

Present mods:
HRC stage III turbo kit (12 psi street, 25 psi track) / HKS 2 1/2" cat back exhaust w/burnt cat / 16" wheels w/Yokohomo tires (215/40) / 420A engine w/ tooled crank, billet crower rods, and 8.5:1 JE pistons / Head ported and polished, 3 angled valve job
Power-stop brakes w/axis pads / Ebachi Pro lowering kit (1.8") / MSD DIS-2 ignition system w/turbo retard

Near Future:
Stand-alone fuel system / 550cc injectors, and fuel rail / TEC III fuel/ecu system / 17” Hart racing wheels / KYB AGX struts, w/ upgraded anti sway bars / Rear brake conversion (front to rear, Brembo in front)

Jay-
wakbrd99@aol.com

97' Eclipse RS (kinda)

Present mods:
HRC stage III turbo kit (12 psi street, 25 psi track) / HKS 2 1/2" cat back exhaust w/burnt cat / 16" wheels w/Yokohomo tires (215/40) / 420A engine w/ tool

i plan on makeing an all out drag car... 25 psi and maybe some nitrous

1997 Mitsubishi Eclipse GS
My other ride is your girlfriend.