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Old 11-14-2008, 08:09 PM   #1
jaed_43725
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Lightbulb Carbureted 2.5

I was wondering if there is a kit out there to turn an EJ253 into a carbed engine. Specifically is there a manifold or kit out there to use a Holley carb? Any info about carbing this engine would be great. Thank you.
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Old 11-14-2008, 08:30 PM   #2
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WHY? If you want ****ty MPG, less power, crappy performance and 1950's emissions levels, then drive a 1976 Camaro.

But seriously, there is no info I've ever seen and no ready-made intake.
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Old 11-14-2008, 08:49 PM   #3
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i always thought a carb'd suby would be sick
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Old 11-14-2008, 09:30 PM   #4
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I think that getting a N/A manifold modded for a carb would be pretty easy. People are always making sheet metal manifolds for V-8's. And using a 13 psi fuel pump with a return line is no biggie. But what about the ignition. Since there is no distributor could you run the ECU to just do spark, or would you need a stand alone? A crank trigger would be too expensive. Any ideas anyone?
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Old 11-14-2008, 09:37 PM   #5
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There is a guy local to me with an older 911 powered by a carb'd EJ25.

http://www.projectaerosol.com/porubi/
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Old 11-14-2008, 10:15 PM   #6
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Look at the changes from the 85 and earlier EA81 and the 86 and later EA82. They basically converted a Carb engine to a single port fuel injection engine.

I say forget about the Carb and instead use one large injector on the throttle body if you want to be unique. A single port megasquirt could run it just fine i bet.

edit: http://home.comcast.net/~trilinear/EA81_SPFI.html This should give you some ideas!

Last edited by ciper; 11-14-2008 at 10:21 PM.
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Old 11-14-2008, 11:13 PM   #7
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The carb'd 2.5 in the Porshe is cool. I am not a big fan of Hilborn injection though. If you could ask him how he gets the thing to spark and post it that would be awesome.

As for one big injector I am trying to cut out as much electronics as possible. I am pretty sure that a small Holley 4150 would be unique enough. However any N/A build will be high compression think 12.3:1 and running 93 octane. It will also run E85 without a problem.

So if I can get the ignition figured out for cheap all I have left is the cams. Does anyone know where I can get a good deal on some radical N/A cams? If so post or PM me. I believe that I can make 250 chp with this thing easy enough. And as for that magical 300 N/A, its just a spray plate and a fogger away.
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Old 11-14-2008, 11:23 PM   #8
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Quote:
Originally Posted by jaed_43725 View Post
The carb'd 2.5 in the Porshe is cool. I am not a big fan of Hilborn injection though. If you could ask him how he gets the thing to spark and post it that would be awesome.
I think he's the NASIOC member named porubi.
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Old 11-15-2008, 01:00 AM   #9
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Quote:
Originally Posted by jaed_43725 View Post
As for one big injector I am trying to cut out as much electronics as possible. I am pretty sure that a small Holley 4150 would be unique enough.
If you are trying to cut things out and make it simple a single injector and driver would be far simpler than a carb. The number of individual parts is probably 10 fold for the carb.
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Old 11-15-2008, 01:23 PM   #10
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The carb will have more parts as far as just parts go. But a carb is mechanical, which is my biggest goal. Also a small 4160 would be real cheap as compared to a single 1,600 cc injector that I will need. Not to mention the injector timing, which would be real problematic considering that at about 4,000 rpm it will be close to 100% duty cycle. Since a carb can fuel my 408c.i. Ford without a hitch then it will work great on a 2.5. I still need to figure a low buck solution to do just spark though. After that I wont need any of the computer stuff for any sensors or anything. It will be one clean engine bay for sure. And I dont care about any emissions stuff, since my state doesnt test for anything except VIN.
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Old 11-15-2008, 11:47 PM   #11
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Can someone instruct a newb how carburetors work compared to injectors and how they are used for performance?
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Old 11-15-2008, 11:52 PM   #12
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Quote:
Originally Posted by Da-Risin-Smoke View Post
Can someone instruct a newb how carburetors work compared to injectors and how they are used for performance?
I can instruct you how google works: You type "how does carburetor vs fuel injection work" and you get over 2.5 million answers to your question.
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Old 11-16-2008, 12:42 AM   #13
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Quote:
Originally Posted by semaj View Post
I think he's the NASIOC member named porubi.

Nope. The car is the Porubi. Wayne's screen name is Poruki.

But that's twin Webers like used on a 912 or 914. As for a Holley that would require some sort of custom manifold beyond the little adapter plates that Wayne made for his Porsche.
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Old 11-16-2008, 11:39 AM   #14
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Quote:
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Nope. The car is the Porubi. Wayne's screen name is Poruki.
Ah yes, that's his name!
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Old 11-16-2008, 02:53 PM   #15
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I know plenty well how a carb works, seeing as how I have an 87' Mustang with a 408 stroker, with a 750cfm 4160. Built to the hilt running high 10's.

I could get a 4150/4160 adapter flange put on a EJ253 intake. I think it wouldnt be that hard really. I know some pretty good shops, and I would just use a Ford throttle bracket that is held down by the carb studs and a Mustang throttle cable maybe modded to fit the pedal.

But the real question here is getting the thing to spark right. If anyone has any ideas on how to do that please let me know. I am going to go for this build if I can make this work. And of course there will be a full write up with pics.
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Old 11-16-2008, 03:30 PM   #16
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To run a single Holley carb on a Subaru engine, get a centermount intake adapter for a four-carb Corvair engine and modify it as necessary.

http://www.corvair.com/user-cgi/cata...n=MAIN&page=63
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Old 11-16-2008, 03:51 PM   #17
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4URABUS thats a neat piece. Either way I go the intake is decided and it will work.

I may have found the answer to my ignition problem by using an MSD DIS-2. I downloaded the manual for it, but didnt get a real clear answer. I can only assume I will need something to read the cams and crank sensors. So I will have to wait until I get back to the states to call them, unless someone else wants to which would be mighty nice.
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Old 11-16-2008, 04:16 PM   #18
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One of the MSD boxes with a properly mounted crank sensor/wheel will do the trick...but whats the point? You have to do extensive intake and fuel system mods for a net gain of 0...probably even a loss. Can you explain the those of us who are confused what your getting at by doing this?
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Old 11-16-2008, 06:47 PM   #19
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Quote:
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One of the MSD boxes with a properly mounted crank sensor/wheel will do the trick...but whats the point? You have to do extensive intake and fuel system mods for a net gain of 0...probably even a loss. Can you explain the those of us who are confused what your getting at by doing this?
You should search our archives for the dyno sheets from Poruki's carbed Ej25 before you make those kind of assumptions. I would hazard to guess that Wayne's car picked up at least 10% more power with the carbs and no other mods (he's using a slightly modified set of Ej205 WRX headers for an exhaust manifold).

The reason for this is that the Ej25 SOHC intake manifold is very restrictive. It doesn't flow very well, and by going over to the carbs, Wayne was able to remove that restriction and give his engine more air.

And to draw from another engine in the Boxer family, when you take a 2.7l or 3.0 H6 from a mid to late 70's 911 you see a dyno prooven gain of 20-25whp on those cars.

Making blanket statements about carbs being going backwards isn't really fair.
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Old 11-16-2008, 07:15 PM   #20
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Quote:
Originally Posted by Matt Monson View Post
You should search our archives for the dyno sheets from Poruki's carbed Ej25 before you make those kind of assumptions. I would hazard to guess that Wayne's car picked up at least 10% more power with the carbs and no other mods (he's using a slightly modified set of Ej205 WRX headers for an exhaust manifold).

The reason for this is that the Ej25 SOHC intake manifold is very restrictive. It doesn't flow very well, and by going over to the carbs, Wayne was able to remove that restriction and give his engine more air.

And to draw from another engine in the Boxer family, when you take a 2.7l or 3.0 H6 from a mid to late 70's 911 you see a dyno prooven gain of 20-25whp on those cars.

Making blanket statements about carbs being going backwards isn't really fair.
Well as the OP stated he will be using a 1 to 4 intake manifold with one central carb which negates the benefits a pricey individual throttle body setup gives. Who knows if it would have made even more power with standard injectors s carbs using an individual throttle body setup. Personally I see it as a dollar to hp gain ratio and this just isn't very good even if it were to gain 50hp. Hence my questioning why the OP wants to do this. Plus who wants the terrible mileage and cold weather driveability of a carb, unless its race only. With that said that built motor is very awesome and had alot of care put into it.
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Old 11-16-2008, 07:51 PM   #21
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A 4 point intake plenum is nothing. Just like at a big block Ford Edelbrock Victor intake, then you will see crazy runners. I already have the intake and the carb is like $50.00, plus machine work will be like $100.00 at the very most. And being that the carb will be very central on the long runners, its about perfect for atomization. The ITB is super expensive. Now to the next part, I plan on getting 300whp out of this thing with nitrous, and as such I can use a carb plate easy enough.

rdodger I can honestly say that a carb doesn't get any worse mileage than EFI. You just have to tune it right is all, and that means dyno tune. Thing is, is that dyno tuning a carb takes a whole lot longer due to jet changes. Cold weather driveability is not impacted at all, trust me I have a lot of experience with high performance carb'd cars. Not to mention I live in N.C.

Now to the ignition. I shouldn't have to use a separate crank trigger and pickup. That's what the cam and crank sensors from the factory are for, and they will work just fine. I will probably only spin the engine to about 7,000 at the very most. All in all it should be pretty wild. I believe that it will be able to keep up with turbo guys easy. If I really need to beat them, then its only a jet change away. And if all else fails then I will put in a carb'd 3.0.
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Old 11-16-2008, 10:21 PM   #22
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You might wanna talk to this guy...and he has a unique all mechanical solution to the ignition issue...

http://www.youtube.com/watch?v=WScRB...eature=related
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Old 11-16-2008, 10:32 PM   #23
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I wish I could watch youtube here. But we have real low bandwidth in Iraq.
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Old 11-17-2008, 04:42 PM   #24
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this is not anything new running an EJ engine with a carb. personally i've only seen it done on the phase 1 ej22 but i believe the concept could be transfered over to an ej25.

the hard part is the ignition. bolting a carb on is the easy part. what you need is a distributor from a ford escort (2.4lt 82-84 i thinks...)

this will go on the back of the passenger side head in the end of the camshaft. the people who have done it can describe it far better than i can.

USMB is the source for carbing. this is just one of the threads covering the topic.

http://ultimatesubaru.org/forum/show...ight=ej22+carb
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Old 11-17-2008, 05:29 PM   #25
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The ford escort distributor solution is something that is specific to the EJ22E because of the way that the cams are installed and being able to access it through the service hole in the back.

There is definitely an MSD unit that will work with the factory ignition system buy the problem there is that the factory ECU won't give you the advance that you need. I really do think that a crank fired trigger wheel is the way to go for the spark.
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