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building frankenmotor

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I don't know about these motors, but on many cars with interference engines- you don't bend the valves with timing belt being off until it is more than 3 teeth off or so..

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  • Author

I went with fel-pro head gaskets. Now i know i should have gone with OEM ones. This being my first subaru engine i had a bit of a learning curve with it. Im hoping just like my fiero i can learn this car like the back of my hand

were they the fel pro metal 3-4 layer or were they the composite shiny paper junk? if they are the metal ones, i have heard talk that they are made by fuji... I could be wrong. If they are the composite, I wouldn't drive the car for fear of trashing my new engine/$700 heads...:banghead:

  • Author

They are the multi layer metal gaskets. I luckily knew atleast that much from reading on here to only go with the layered metal headgaskets.

I was reading a discussion a while back where someone said that the fel pro MLS gaskets had a fuji "boomerang" stamp on the corner tab next to a rivet. It's been a while though

  • Author

ill have to keep an eye out for that if i see another set of there headgaskets

Since I'm going to be building a craptastic motor for my car, maybe I'll grab a set of the mls felpro ones... They're a lot cheaper.

Do you have a link or part number to it?

There are several superseded part numbers for 25D head gaskets. It's anyone's guess as to which iteration the Fel-Pro ones are, if any, or if it matters at all.

 

I'm sort of a believer that Subaru wouldn't go through the trouble of new part numbers unless they were changing something, and that they don't change something unless there's a reason.

 

Just because it has a Fuji boomerang doesn't mean it's the best:horse:

 

Jacob

Hmm, not that much cheaper than OEM, IIRC. I'm sure there's something more craptastic out there, if that's the goal:grin:

 

Jacob

 

I thought oem was a lot more than that. I get 15% off though from the dealer, so it might not be that bad.

hello, jack:

 

is a 96 - 98 ej25 short block with 90 - 95 ej22 heads an interference engine????????????

 

i have heard that it is the pistons that cause the interference, not the heads, but i have also heard that the DOHC engines were valve to valve interference, not valve to piston.

 

does any one know??

 

EDIT: i'll start a new thread if you think i should.

hello, jack:

 

is a 96 - 98 ej25 short block with 90 - 95 ej22 heads an interference engine????????????

 

i have heard that it is the pistons that cause the interference, not the heads, but i have also heard that the DOHC engines were valve to valve interference, not valve to piston.

 

does any one know??

 

EDIT: i'll start a new thread if you think i should.

 

From what I've read and the way I understand it is, the pistons 97 and up made the engine interference. Regardless of the head. So a 96 2.5 DOHC would be valve to valve, but clear the pistons.

the whole point of the franken motor is to bring the comp ratio up, ej22's come with less dish in the pistons. I would assume that the piston will interfere with the valves just because of the "taller" piston

Well, since I'm building a craptastic frankenmotor it'll probably end up with rod knock sooner than later so then I can see if it's interferance or not... :P

  • Author

Another question i had is after i get headers and exhaust is there anyway i can tune this setup with the stock ECU to take advantage of the high compression even more or would i need a stand alone ECU to do any tuning

the whole point of the franken motor is to bring the comp ratio up, ej22's come with less dish in the pistons. I would assume that the piston will interfere with the valves just because of the "taller" piston

 

Actually, it's to increase the displacement. The increased compression ratio doesn't count for that much of the increase in power. Read the original thread if you want more info.

 

Another question i had is after i get headers and exhaust is there anyway i can tune this setup with the stock ECU to take advantage of the high compression even more or would i need a stand alone ECU to do any tuning

 

If you're using your 91 ECU, then I'm not aware of any tuning you can do unless you're a computer engineer or something with a lot of time on his hands. This is where the point of the Frankenmotor is lost on a lot of people. It's a cheap increase in power. The gains from tuning this setup are minimal, at best, from what I've seen.

 

Jacob

 

P.S. Not to say that I'm not going to run Megasquirt someday:-p

Stock ECU, with a *SAFC II or other piggiback and a wideband 02 sensor... would allow you to tune just slightly better..

I just heard from a sub guy that a *Super AFC works well on these early 90's EJ22 motors that love boost

 

but the frankenmotor will run pretty good and mostly as it should using the

STOCK AIRFLOW SENSOR

STOCK INJECTORS

STOCK ECU

(which were all designed for each other)

 

similar to putting a larger turbo on a stock turbocharged car that is still running the same boost level as it was before... still has all the same fuel parameters

Edited by TajMan

Actually, it's to increase the displacement. The increased compression ratio doesn't count for that much of the increase in power. Read the original thread if you want more info.

 

 

 

If you're using your 91 ECU, then I'm not aware of any tuning you can do unless you're a computer engineer or something with a lot of time on his hands. This is where the point of the Frankenmotor is lost on a lot of people. It's a cheap increase in power. The gains from tuning this setup are minimal, at best, from what I've seen.

 

Jacob

 

P.S. Not to say that I'm not going to run Megasquirt someday:-p

 

Then why swap the heads on the 2.5? the 2.2 heads don't flow as well... but make up for it with a smaller combustion chamber than the 2.5 heads thus increasing the compression ratio.

Then why swap the heads on the 2.5? the 2.2 heads don't flow as well... but make up for it with a smaller combustion chamber than the 2.5 heads thus increasing the compression ratio.

 

Well, when you start with, say, a '91 Legacy, you start with a 2.2. The Frankenmotor keeps everything except for the block. Buy block and head gaskets, and you have more power. The bump in compression is icing on the cake, but not as cool as more displacement.

 

On my Brat, I would have swapped the whole 2.5 so I could get the better-flowing heads, but 2.5 heads won't fit.

 

Seriously. Read the Frankenmotor thread, or at least every post by Matt Monson in that thread. You'll learn everything you need to know, including times when you're retarded if you opt for a Frankenmotor:)

 

Jacob

But people report power increase when they have a 2.5 DOHC in their car and then swap on 2.2 heads. Therefor it must increase power. Unless their butt dyno is broken...

But people report power increase when they have a 2.5 DOHC in their car and then swap on 2.2 heads. Therefor it must increase power. Unless their butt dyno is broken...

 

Power gains can be questionable on a real dyno. Butt dynos are notoriously unreliable. There are thousands of shiny things on eBay that prove that.

 

Jacob

Seriously. Read the Frankenmotor thread, or at least every post by Matt Monson in that thread. You'll learn everything you need to know, including times when you're retarded if you opt for a Frankenmotor. Jacob

 

there are 145 threads with frankenmotor in them, can you give me a hint on which one to read? was his user name matt monson?

there are 145 threads with frankenmotor in them, can you give me a hint on which one to read? was his user name matt monson?

 

It's on NABISCO, and it's called "High Compression Frankenstein". Yes, that's his username.

 

Jacob

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