High Output EA82T

[garner]

I am about to rebuild an EA82T

 

What things should I consider doing to the internals to get more H.P and Torque?

 

Anyone have experience or atleast ideas about the cost effectiveness of the following proceedures?

 

Cam regrind?

Pistons?

Shave heads?

Port/Polish?

Valves?

 

I'd like to get the HP up to about 150-170 or higher. What should I do inside while all the parts are scattered all over the shop?

 

I will be using this motor on the street primarily(to smoke hondas

) and some rally x and auto x.

[carfreak85]

get a carbd short block and rebulid that and put the turbo heads on it then throw it in your car. they have a higher CR so Id use 91-92-93-94 octane gas. makes it more efficient.

[MilesFox]

I ported the heads on my 87 gl-10. the turbo came on a lot stronger at lower rpms. Run a fatter Down-Pipe, if you can have one made, or simply run at least a 2 inch pipe out the rear, with a hi-flo muffler. a turbo is not necessarily that loud without a muffler, and if you run the pipe out tha back or side of the passenger compartment, it wont be loud inside (indiana law requires the exhaust exits past the passenger area)

 

the carb block will get you 8.5 compression vs, turbo 7.7 compression. but the pistons from a carb motor will fit in the turbo block, if you wanted to keep the rods and crank stroke of the turbo engine

 

shaving the heads wont really accomplish much, you dont want to take more than .010" (just to give a clean surface) as it would make the motor too narrow for the intake if you go much more than that.

Subaru Junkie i believed shaved his ea81 heads, so ask him abut how much he took off.

the pistons or block swap will well than make up for what shaved heads can do

 

you might be able to find lighter valves, but i dont think you can go much bigger at all. the webbing between the valve seats id pretty yhin, and has a tendency to crack between the valves.

Now it is common for the valves to crack between the valves, but thatis considered normal, as i believe there is a TSB out about it.

But if the head goes bad, it usually drops a valve seat. all the heads i have seen that were too bad to use had the valve seat drop. the crack should be nice and flush with the surrounding metal. worse cracls will "fillet" out, enough to stick a fingernail in.

the crack may go down towards the valve seat. thereis no water passage there, i had a crack that went TO the valve stem, and ran , but it dropped a valve seat later.(but this motor had 2 blown head gaskets when i got it) heads will drop a valve seat more than anything, the cracls in the exhaust port are the ones to watch out for. you may find a small 1cm crack by the spark plug hole, but that will be alright.

but if you have a known good motor, the heads are nothing to worry about

They say Gen 3 heads are the best, off later model turbos

 

if you know thew bottom end is in good shape, it can handle a good 150, good enough for a cost-effective build

 

you can also use xt mpfi spider intakes, in conjunction with impreza intercoolers, or make some kond of hi-flow intake and filter.

intake and exhaust alone will free up some hp. you can modify the wastegate or use a boost controller to get more boost, you can go a good 12-13 psi before you have to worry about an intercooler.

 

with the carb block, use a slightly higher octane, and tweak the timing.

 

wjm on the board had turbo on an spfi block 9,5:1 cr, with hi-octane gas. ask his expertise about driveability and reliability of high compression

 

somewhere on the board there is an electrical mod to the MAF to bypass the fuel cut-off

[garner]

Thanks guys,

 

Miles, where do you find the time to write such in depth posts, you must work for the state or something:D

 

Why are compression figures different on the two blocks? It seems like a turbo engine would want more compression?

 

What years/cars had the spider intakes?

 

Any advice on cam re-grinds?

 

thanks

[MilesFox]

the turbo has lower compression for knock purposes. but the turbo has the potential to cram more air in the CC than just compression alone. i guess it gives more volume to cram air into, moreso than a higher comp. motor

 

i can go in-depth with my posts, because thatis what i have done. and from what i have learned on the board. sometimes no one wants to answer the same posts all the time, but i dont mind. people recognise that i have a good wealth of knowledge exclusive to my endeavors. good luck on your projects.

 

check out my new website, it will give you more of an adea of what i am doing with soobs

http://www.warpthree.com/milesfox/enter.htm

[XSNRG]

I don't want to start a debate here but I did just read that it's better to use lower compression with more boost than higher compression with less boost. This is in the current Hot Rod Mag. It makes sense too, if there is more room in the combustion chamber you can get more air/fuel in there. They claim it's more effecient.

[MilesFox]

your power is not going to come from how much pressure is in there but how MUCH air(volume) yu can get in there.

 

the boost will act like your high compression, but the volume will allow MORE air to be compressed under BOOST

[WJM]

Hey Miles, i looked in the owners manual for the specs, and carb block have 9.0:1, and the FI blocks have 9.5:1....yet they have the same bore and stroke, and pistons. Heads seem to be the same. I dont know how they get different compression from the same engine, with a different fuel system. Hmmm.......

 

I almost would not recommend doing a 9.5:1 bottom end...you have to be very careful on tuning in the timing, and you ABSOLUTELY HAVE TO RUN the highest octane street fuel, short of competition fuels, at ALL TIMES. At this time, I have NEVER run more than 8psi of boost on this, and I wouldnt recommend it without a proper intercooler setup.

 

Under load, even on 8 deg of timing, before boost comes on, when the vac advance on the dist kicks in, it STILL detonates. The ONLY solution to this is 100 octane competition fuels. THEN, you can run 25 to 30 deg of timing, and it'll boil all 4 tires, with an otherwise stock setup.

 

Otherwise...run 4 to 5 psi, and an intercooler and 20~25 deg of timing, and it'll be fine. If you dont run an IC, and 8psi of fuel...retard the timing way back or run competition fuel.

 

But still.....this engine have mucho low end torque.

 

Oh and more MPG.

[bushbasher]

the compression makes little difference in how much air you can get in there. A change in piston size will make a very small decrease in volume when the piston is making it's way to the bottom, which is when the air comes in. However at the top the difference is larger, because the overall volume is much smaller. Small % diff at bottom big % diff at top. You will get a tad less volume, but ALOT more compression.

 

Putting a turbo on doesn't increase volume, volume is a measurement of space. It puts the volume under pressure, meaning more molecules are pushed into the same volume, so that you have more oxygen to burn with. Pressure can be looked at as a larger volume forced into a smaller volume, so in a way you are right Miles, it has to do with volume, but it is also in a way directly about pressure. However we are also talking about 2 pressures. The turbo pressure increases the amount of air molecules, allowing more fuel to burn per ignition, whereas the combustion pressure pushes the molecules closer together so they basically can react faster and more violently.

 

The problem now is that the turbo pressure affects the combustion pressure, as the volume is starting at a higher pressure. This raises the compression pressure, as the piston now has to force a larger amount of molecules into the same small space. To know just how much boost raises the compression would give a better idea as to whether high boost or high compression is better. To increase both would be ideal but we are limited by octane, head gaskets, and the botttom end.

 

whew. Some of that may be a little obvious, but I'd like to get all in one shot.

[Dennis ex24]

Originally posted by garner

I am about to rebuild an EA82T

 

What things should I consider doing to the internals to get more H.P and Torque?

 

Anyone have experience or atleast ideas about the cost effectiveness of the following proceedures?

 

Cam regrind?

Pistons?

Shave heads?

Port/Polish?

Valves?

 

I'd like to get the HP up to about 150-170 or higher. What should I do inside while all the parts are scattered all over the shop?

 

150 flywheel HP is possible with out doing pistons, shaving heads and grinding cams...but the key to more power is what you listed above. ill estimate my XTs HP being in the neighborhood of 180 (flywheel) HP as it sits now with an overbore of .050 and headwork done with the addition of a bigger turbo at 13PSI.

 

cams leave alot to be desired, and so does the turbo and exhaust. WJM on this board had cams done that were supposed to harness a 20HP increase but i havent heard anything else about it...i have a stock WRX exhaust system which may have increased the volume of air leaving the engine but im also still retaining all the cats in that system - for now...the car needs at least a downpipe to be somewhat serious though.

 

the stock turbo runs out of breath after 14PSI and i really havent seen any swaps done other than the one on my car. there is a legacy unit is on mine which seems to hold its own at 15PSI and moves plenty more air than the original. a 16G from a mitsubishi maybe a better alternative because the manic levels of air it blows and how effecient it is. it also very much resembles the legacy unit from what ive seen.

 

another thing that will need attention is the ignition system...an MSD box would perfect for this but from what ive seen and heard its a pain to get these cars to run right with them. im using an MSD coil now and this should be considered before anything else when talking in terms of performance in my opinion...every little increase in spark on our cars will help.

[garner]

thanks guys

 

I'm still digesting the compression issue and am certain I will understand soon.

 

It does seem like the carb block would cause some hassles and performance would barely justify the difficulty?

 

I read some posts on Delta cams and that seems like a promising mod. The torque grind that WJM got sounds like alot of bang for the buck. I have not found any posts from WJM about performance after the cam regrind so I don't know how true the +20h.p. hp figure is. $135 is a pretty good deal if you really get that much pep.

 

Dennis ex24, what did your "head work" consist of besides the standard valve job?

 

Alot of folks mention the "spider intake" I don't believe I've ever seen one. What vehicles might I canabalize for one of these drool worthy intake manifolds?

 

 

thanks again and keep the ideas coming

[Nug]

Forced induction. Sort of artificially raising the compression ratio.

[WJM]

I'm still digesting the compression issue and am certain I will understand soon.

 

Its really simple: lower comression=less overall power. More compression=higher overall power. *NOTE: There are different aspects of tuning to get max power out of certin setups*

 

Carb/MPFI/SPFI block: Well...depends on the fuel and other things you run. FOr regular street use, i think it would be best to have an auto behind a 9.5:1 turbo engine. YOu can use a 5spd tho, thats what i run. You will get gobs more power from it if you run the right fuel in it, say 100 octane. But with regualr pump gas...youd have to retard the timing, and the only thing you get over the stock turbo block is more low end grunt...and DONT run anything less than 91 octane!!

 

Now to the cams.....pulls like a freakin rocket. To no end too. INSTANT turbo spool...but, ive got some severe intake and exh mods as well.

 

Spyders? On any XT, 87.5 and up.

[tailgatewagon]

as is my understanding (please correct me if im wrong) that the spider intake was only on the 87 1/2 xt 4turbos. the production date starts at jan of 87 and gos to 6 or so of 87 (remeber that production years start at half years. like 87 started at june of 86) anyway.

 

i belive that in 88 the xt6 came out and so the turbo hipo xt4 died and was replaced by the xt6. so i think there is only half a year with theis intake on it.

 

as for the performace mods....

 

well if you read about wrx's supras and gtrs that have had thousands thrown into them they seam to leave the compression way down in the 7-8 range and just run more boost..

[archemitis]

but those guys are runing 20+lbs. on a car that is going to push around 10 lbs, 9:1 to 9.5:1 is doable.

[WJM]

non turbo spyders are plentiful to find. I got two for free. I got my turbo one off of an engine.

[bushbasher]

the "side effect" of turboing an engine is the increased compression, the real gain is provided by providing more air to the combustion chamber allowing for more fuel to burn. compression doesn't change the amount of air it gets, it changes the area that that amount of air gets compressed to after the intake valve has closed, and the spark plug is about to go.

[garner]

I get the compresion deal now, Thanks for all your explanations.

 

so as for the spider intake, I want a turbo one off an 87 1/2 XT?. And the label on the door will say it's an 88?

 

What is the difference between the Turbo and Non Turbo spiders?

 

thanks

[tailgatewagon]

just look under the hood of every xt that you find. and see if it has a spider intake on it. it looks like a legacy intake(if you havnt seen one go to a subaru lot and look under the hood)

 

i dont know the differnces of the spiders (non turbo vs turbo) i think one may have mpfi and one spfi. but that is only a guess...

 

as for 87 1/2 xts they are very rare (ive only seen 2) but that dosnt meen there arnt alot around just spread out very thin.

[WJM]

ALL Spyders are MPFI.

 

It is rumored that the EJ18 was offered as TBI/SPFI (throt. body/single port fuel inject. Same thing really), and MPFI.

 

The differeces, that I know of, between turbo and non turbo spyders...are as follows....

 

Injectors

Turbocharger coolant return to the t-stat housing

 

yeah, thats all I know.

 

Pleadies and i came accross something strange...I have two 87+ turbo intakes (one on my RX, and the other aquired some elsewhere), both have different wiring harnesses. I have a single turbo spyder, and two non turbo spyders. Both the non turbos have different wiring. One will plug right up to my RX, while the other one (pleadies's now), the turbo, and that other standard turbo one, wont plug up. Different connectors and harness.

 

Hm...I still have the standard turbo intake, the spyder turbo, and the N/A spyder that has the similar to 89 RX wiring harness. Experimenting will commence the first of the year me thinks.

[garner]

So I am looking for something like this?

 

http://usmb.net/albums/albuo24/spider_top_XT2.sized.jpg

 

It's from a non-turbo 88xt I'm told.

 

Is a non-turbo spider workable on a turbo engine? I understand there are wiring issues but is it just a matter of getting things connected?

 

thanks

[StormTrooper]

If you want to maximize torque, and are going the carb route, you will have a disty that can be recurved, which can account for over 10 lbs. ft. torque

[RedRX]

WJM - what were those cam specs again? particularly the timings and durations ie degrees opening/closing for exhaust and inlet.

[garner]

RedRX

 

I found them here

 

http://usmb.ultimatesubaru.org/forum/showthread.php?s=&threadid=6918&highlight=cam

[WJM]

Yeah. there they are.