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Carb Block VS. Turbo Block (EA82T Rebuild)


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43 replies to this topic

#1 TheSubaruJunkie

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Posted 06 December 2005 - 11:25 PM

So I've been juggling this around in my head for weeks now. Since I will need a new block for the RX, why not take the plunge and get the carbbed block with increased compression ratio? Why Not? Well, i dont know why not :) So I decided to post here about it to see what you other turbo guys out there think.

Here are some reasons I have already gathered on why not to do it:
1) Limited amounts of boost need to be ran. No more 10psi.
2) Higher emissions ratings, possibly effecting smog results (huge here in CA).
3) ... well, so far thats really all I can come up with.

With that being it, here are the advantages Ive come up with.
1) Better low end power.
2) Easier to find in a junkyard
3) Chances of being overheated or abused are much less likely than a turbo'd block.
4) Higher compression at the same cost.

I will be looking for a block in the junkyards. Lately here in town my luck has run out, as there are no EA82T's in any of the yards. Plenty of other EA82's tho. Im thinking my best luck on a used block would be to find something with very low miles, and to look for a subaru with extensive body damage. Something that looks like it suffered premature death, not by engine failure. Thats going to be hard to find in a Turbo :-\

Decisions... decisions, decision!
-Brian

#2 Jibs

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Posted 06 December 2005 - 11:32 PM

I'd go with the carbed block Brian, I *think* that runnung your turbo engine with the boost up high might've had something to do with it blowing up, but thats my opinion.:) But it is up to you and I know that the california smog guys are monsters for emissions so.... Its up to you.

#3 TheSubaruJunkie

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Posted 07 December 2005 - 12:02 AM

I guess what im really affraid is doing the Carb block with higher compression and then blowing the car up again in a couple months. Or not doing it, using a low compression block and always wondering "What if...?"

My car could use some low end power, and I guess i could stick with stock boost.

-Brian

#4 Subarian

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Posted 07 December 2005 - 12:11 AM

3) Chances of being overheated or abused are much less likely than a turbo'd block.


The turbo heads actually suffer more than the block from abuse. Your MPFI manifold won't bolt to the NA heads. Just something to consider, although I have a carbed EA82 I'm getting ready to put a turbo on.

#5 calebz

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Posted 07 December 2005 - 12:25 AM

The turbo heads actually suffer more than the block from abuse. Your MPFI manifold won't bolt to the NA heads. Just something to consider, although I have a carbed EA82 I'm getting ready to put a turbo on.


When doing what brian is suggesting, you don't have to worry about the manifold and heads.. turbo heads on a carbed block works fine.

Brian.. Wy no more 10PSI? thats right about where mine is at and its been ok so far.

Also, you say that the chances of being overheated and abused are less with the carb block. How so?

#6 TheSubaruJunkie

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Posted 07 December 2005 - 12:41 PM

Cause carburated EA82's are gutless and weak. Primarily owned by older women drivers who dont go past 70mph. I also doubt the Carbbed motors are prone to cyl #3 failure like the EA82T guys seem to have. Head gasket failure, rod bearing failure etc...

And caleb is correct. The only part of a carburated engine i'll be using is the block, I will need to use my MPFI heads and all my turbo gear (manifold, intake etc...)

Caleb, how many miles do you have on your motor? Is it your daily driver?

-Brian

#7 HooptyGL

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Posted 07 December 2005 - 02:04 PM

Cause carburated EA82's are gutless and weak. Primarily owned by older women drivers who dont go past 70mph.
-Brian


whoa man speak for yourself....my hoopty wagon seldom travels under 80 mph on the highway...unless im going up hill.

http://www.ultimates...&cat=500&page=1

the weber is a definate improvement...it would be interesting to drag a carbed ea82 against an ea82T

http://www.ultimates...&cat=500&page=1

the car has that much on the body...the previous owner blew up the original engine when the car had less than 99k on it...the jdm runs like top though.

#8 TheSubaruJunkie

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Posted 07 December 2005 - 02:37 PM

Thanks hoopty... but that helps me none.

-Brian

#9 calebz

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Posted 07 December 2005 - 02:45 PM


Caleb, how many miles do you have on your motor? Is it your daily driver?

-Brian


I now have about 6k on the motor. Its not my daily driver. 17mpg or so, plus the fact that its not unheard of for me to drive 300 miles in a day for work, means the wagon was not a good daily driver candidate (for that matter, no 20 year old car was a good candidate)

I won't say its been a flawless 6k, but none of my problems have been related to the carb block swap.

#10 TheSubaruJunkie

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Posted 07 December 2005 - 02:46 PM

Anybody else running a 9.5:1 block on their turbo? Need some more input.

-Brian

#11 Marck

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Posted 07 December 2005 - 03:52 PM

What are you going to do about the knock sensor and that PCV pipe coming out the rear of the block? I think they only came in turbo blocks. I think what you really want is a turbo block with carbed pistons.

#12 calebz

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Posted 07 December 2005 - 03:58 PM

What are you going to do about the knock sensor and that PCV pipe coming out the rear of the block? I think they only came in turbo blocks. I think what you really want is a turbo block with carbed pistons.


The bung for the knock sensor is already there on the carb block.. theres just nothing in it. The turbo knock sensor screws right in.

#13 Subi81

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Posted 07 December 2005 - 05:17 PM

There is a reason that Subaru lowered the compression on the turbo block. If you ran the car with a turboed 9.5:1 CR block. You would for sure need to run higher octain gas (92 and higher). And any ping no matter how small (audible or not) would completly destroy your engine. Most kits on the market today that turbo higher compression blocks run in the 5 psi range NOT 10 psi, and that is running newer engine managment. I have an AF gauge on my 86 when the intake goes into the positive pressure range the AF reading is still bouncing back and forth for a split second then it goes full rich. Yes I know that subaru changed the engine managment after 86 so maybe it is better. Personally I would get an auxillery injector on that thing before boosting and the obligitory intercooler with freash air cooling it. Did you ever get a scoop on that thing? Good luck

#14 TheSubaruJunkie

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Posted 07 December 2005 - 05:28 PM

Never got a scoop. I will have the intercooler on the new setup for sure with better air flow. I know all the logistics about turbo's and lower compression engines, and why they need lower compression.

HOWEVER...

There seems to be a handfull of people on the board who have done the swap successfully. None of them have reported premature engine failure, at least I dont think they have (part of the reason for this post).

As far as the PCV stuff.... i dont care about the vent in the block. The bung for the knock sensor is there and tapped already, so it will work. I was going to completly re-do the PCV stuff anyhow, try to keep blowby out of the intake at all costs. Thats a completely different post due in its own time... i just wanna get a running motor 1st.

Who else is running high comp pistons? Will... JWX?? I know theres more than just caleb out there.

-Brian

#15 calebz

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Posted 07 December 2005 - 06:46 PM


Who else is running high comp pistons? Will... JWX?? I know theres more than just caleb out there.

-Brian



Me
Will
Miles


Thats all I can think of at the moment

#16 4WDFrenzy

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Posted 07 December 2005 - 07:45 PM

Hey Brian, I think a carbed block would be okay. If I remember right, part of the EA82Ts low compression(7.7:1) is a result of shorter rods(if I'm wrong, someone please correct me) and also low compression pistons. So if this info is right, you could probably put in some aftermarket pistons to lower the compression to either 9.0:1(flat top) or even 8.0:1(dished), which would help to ease your mind as far as durability and reliability under mid level boost conditions. You may even be able to find forged rods for it to help insure that the only weak points would be the headgaskets or the crank(possibly). Honda guys usually run 9.0:1 compression pistons in their high horsepower turbo applications, so I think a subie block would be fine.

Patrick

#17 Island Roo

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Posted 07 December 2005 - 08:22 PM

im thinking of using the carbed block also just dont want to tie up my turbo car w/ no motor while its snowing, gonna have to find a pair of turbo heads and all the other paraphnalia, i have 2 running EA82 carbed cars slready for parts

#18 TheSubaruJunkie

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Posted 07 December 2005 - 08:27 PM

I came home today to find my gasket kit waiting for me on the doorstep. So now all i need is a block and im set (hopefully i dont need new heads).

Im leaning toward the carbbed block. Nothing ive read has convinced me otherwise. This weekend is the weekend to look, who wants to go to the junkyards with me? (Sacramento, then Reno NV if i cant find what I need).

-Brian

#19 4WDFrenzy

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Posted 07 December 2005 - 08:35 PM

Well, I would go with you, but, ummmmmm, well, I'm kinda in Okinawa right now. I'm sorry. LOL:lol:

Patrick

#20 TheSubaruJunkie

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Posted 07 December 2005 - 09:00 PM

Well sorry but I cant wait for you :D I gotta get this engine put together. I was thinking to myself earlier and I wondered if the EA82T heads are the same as MPFI? Would having a 9.5:1 block be like having a standard MPFI engine... meaning i wouldnt even need the turbo anyway?

-Brian

#21 Island Roo

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Posted 07 December 2005 - 09:32 PM

from what ive seen they are the same MPFI & Turbo

#22 WJM

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Posted 07 December 2005 - 09:36 PM

Cranks are all the same.
Rods are all the same.
Blocks differ with the rear crank case vent, knock sensor port is present on ALL EA82 blocks.
Pistons are ALL the same between SPFI, MPFI, and CARB. PERIOD.
Turbo pistons make the compression difference.

I get 37 MPG on the hwy with my 9.5:1 block. 26~32 around town.

TWE header
TWE VF7 Downpipe
Stock VF7
STOCK MPFI engine systems, controls...etc....
Air-Water IC
Intake

#23 TheSubaruJunkie

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Posted 07 December 2005 - 09:54 PM

You didnt mention heads Will.

-Brian

#24 WJM

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Posted 07 December 2005 - 09:56 PM

heads are all the same.

:drunk:

MPFI and TURBO heads are the same with the exception of the ports on the 1-3 head for the oil line, coolant line, and oil return. If you look on the 2-4 head...well, its the EXACT same casting...but w/out the ports tapped or they are blocked with a bolt.

SPFI and CARB heads appear nearly the same.

#25 TheSubaruJunkie

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Posted 07 December 2005 - 10:01 PM

Ok so this would be like putting a turbo on a standard MPFI engine then.

Here's another question? Can i make the VF7 produce LESS than 7psi (what the wastegate is set at). This would be for long hauls, 300 or 400 mile round trips to Reno. Also, it wouldnt be hard to drill through the block to insert a PCV port would it?

-Brian




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