The RX took a dook

[calebz]

Originally posted by WJM

Yeah, I know. my 1986 owners manual states that as 9.0:1.

So when I was searching for engines, I was at a local subaru place, and I asked for carbed shortblocks, and not SPFI, they asked why, and I told them about the lower compression for turbo, which is why i want the carbed SB. But they said BS, its all the same part numbers. the only thing different is the fuel system. After looking at pistons for the SPFI, carb and MPFI, and seeing that they are all the same.......so, all non turbo EA82s are 9.5:1...unless the heads are different.

 

So, until i see partnumbers and actual USDM engines what are otherwise...i firmly believe that all are 9.5:1.

 

Some one please feel free to disprove me! I do not mind.

 

I spoke to the head tech at the local soob dealership today. He didn't have the answers for me, so he called the subaru 'dealer tech support hotline'.. He was told by SOA that there is a difference in compression between the spfi and carbbed models, and that it is a function of the pistons. carbbed models are flat, spfi are slightly convex.

 

Part numbers are as follows, I used model year 1987 for reference.

 

Carbbed pistons- PN- 480057110

SPFI pistons - PN - 12006AA030

[MilesFox]

the short block we used was from an 87 carb 4wd 5spd wagon.

 

well, we got it running today. the rotor was right on, we switched some wires, and gave it a shot of starting fluid. it started to fire, i turned the distributor and it lit up.

 

we started out at like 10deg btdc, but found that it would not pull much past 4000 rpm, so a little tweak more, better. still no complaining from the engine. so now the timing is just a HAIR ABOVE the stock timing, motor pulls all day. we started on 87 octane, so we topped off with 87. i dont think we will have to worry about knocking the timing back till we get into boost mods.

 

in first gear, rolling, mash the gas and the turbo comes on at 1700 rom, vs the 2500 it did before. you can get a god pull before the boost lite comes on, as the higher compression helps out in the torque department. i think if we can eliminate the exhaust, use fat pipes and acherry bomb, it will let the heads breathe better. cherry bomb right after the down pipe will be the idea to use.

 

we also cut the bottom of the air box out, you can hear nice turbo noises between shifts.

 

the throwout bearing was creaking a bit, but it goes away after the car is driven around. we will have to keep an eye on that....

 

so now we stuffed 13.32 gallons of gas, and reset the trip meter. the car has about 10 miles before the trip reset, so the trip will measure the fuel economy, and the miles on the motor since it was put back together.

 

I would rate this build as a success, now we have a good platform to build further on

[WJM]

calebz:

 

ok, i stand corrected.

 

Miles: your engine will certinly not detonate as much as mine will, as I have the true 9.5:1 SPFI shortblock.

 

Great to hear that its all running great! Keep us posted!

[calebz]

Way to go Fox! Sounds like you're on your way to a winner

[MilesFox]

4wd donuting wit the diff lock on dry blacktop with 205/55 16 inch tures was no effort for the RX!

 

i'm sure we picked up at least 15 hp

[myossfeece]

Well I have about 200 miles on the motor so far and it is running good. Deffinately more torque to go around and the turbo light seldom comes on and when it does it is barely on before going off again. The car pulls great and barely uses the turbo anymore. When I am getting on it tho, thats a whole nuther story, the light comes on and the pulls to no end.

[WJM]

Yeah, you'll have that sometimes.

 

Its a great setup for the low end. With my higher compression, i really have to use race fuel to utilize the high end.