Jump to content


Welcome to Ultimate Subaru Message Board, my lurker friend!

Welcome to Ultimate Subaru Message Board, an unparalleled Subaru community full of the greatest Subaru gurus and modders on the planet! We offer technical information and discussion about all things Subaru, the best and most popular all wheel drive vehicles ever created.

We offer all this information for free to everyone, even lurkers like you! All we ask in return is that you sign up and give back some of what you get out - without our awesome registered users none of this would be possible! Plus, you get way more great stuff as a member! Lurk to lose, participate to WIN*!
  • Say hello and join the conversation
  • Subscribe to topics and forums to get automatic updates
  • Get your own profile and make new friends
  • Classifieds with all sorts of Subaru goodies
  • Photo hosting in our gallery
  • Meet other cool people with cool cars
Seriously, what are you waiting for? Make your life more fulfilling and join today! You and your Subaru won't regret it, we guarantee** it.

* The joy of participation and being generally awesome constitutes winning
** Not an actual guarantee, but seriously, you probably won't regret it!

Serving the Subaru Community since May 18th, 1998!

Guest Message by DevFuse
 

Photo
- - - - -

Ideal carburettor for EJ25?


  • Please log in to reply
47 replies to this topic

#26 Phizinza

Phizinza

    Yip yip

  • Members
  • 3,872 posts
  • South Australia

Posted 23 September 2013 - 06:39 PM

I have a little bit of Subaru background.

 

8 years ago I bought a Brumby (BRAT) as my first car. It had a true dual carb EA81 in it, some lift etc. I bought 27" tyres for it, bullbar rollbar etc etc. Still not content I installed a EJ22 with EFI. The task was not over my head and it would be pretty easy for me to do again.

http://www.ultimates...hl=+ej22 +ft4wd

 

I had trouble with the EFI a lot though and it costed me a fair bit of money for all those little things you don't think about when installing an engine. First up was the fuel lines, they need to be upgraded to EFI ready. And a fuel pump.. Then there is the old sensors on the engine, that need replacing because they throw codes. And you have to hook up custom VSS and blah blah.. Oh and don't get me started on the never ending IAC issues!

 

I've also had much experience with the model of car the EJ25 I have comes out of. The EFI has run me up the wall with issues so much so I am getting rid of the car because it pisses me off with drivability all the time. Half of these issues are to do with EFI programing. I can't see why it runs the way it does, but that is how Subaru programmed it and due to its age it is not re-programmable. And a aftermarket computer is $$$.

The symptoms I am having include touchy throttle (because of the IAC opens by itself as soon as the ECU detects TPS change) This means I cannot cruise at 50 to 60kph without going on and off the throttle. The engine is also plagued by a knock code which for the life of me I can't stop popping up. I've tried changing the plugs/coils/leads/fuel/knock sensor/MAP/IAC/etc. I've also logged the ECU readouts while it has done it which show no reason why it is doing it either. When this code pops up (normally when I need to accelerate to change lanes or what ever) the car loses power and pisses me off even more.

 

So. Now my experience with carbs.

 

I can, and have, stripped down and cleaned carburettors on the side of the road and been back on my way within 20 minutes. They have caused less issues than EFI has in my driving experience.

They are much easier and cheaper to setup with LPG.

They have been proven to be able to supply good power.

They can be diagnosed with eyes, fingers and ears (not computers).

When they go wrong (in my experience) they still limp you home. 

 

Now just to let you know, I study and teach IT at VET level. Not automotive IT, but I do have a understanding of programming and how to use computers.

 

This all leads me to the point where I want a carburettored car again. And as much as I love the EA81 engine, it just doesn't have the potential (with the dollars I have) for the power I require. However, another Brumby with a 2.5l carb'ed engine should do it just fine.

 

 

Thank you people for your help and suggestions so far. And no the the SU, not a fan of those carbs.



#27 Uberoo

Uberoo

    Subaru Wheeler

  • Members
  • 3,436 posts
  • lewiston,ID

Posted 24 September 2013 - 01:16 AM

Your fuel injection problem list almost reads like my carb problem list.I never really had to deal with those issues.My swaps have always performed flawlessly.In fact it almost seems like a wiring problem of some sort,maybe even a bad ground or something similar.In fact I have never even hooked up a clutch switch or VSS .There might have been a CEL from no VSS but it never affected drive ability. My engines and sensors were not new,many times they were lifted straight from the junkyard with no work to them. Well, I am sorry to see you had so many problems.



#28 Phizinza

Phizinza

    Yip yip

  • Members
  • 3,872 posts
  • South Australia

Posted 24 September 2013 - 01:41 AM

Trust me when I say I checked, double checked and triple checked grounds on both cars mentioned. Hell, the outback has about 6 grounds to the engine, all freshly cleaned, still all the issues. I'm not saying EFI is bad, I'm saying I want a carb. I don't care what others want, if they are happy with the EFI then good for them. I've done it, and made up my mind that I want to try a carb. Thank you

#29 NorthWet

NorthWet

    Eeyore Incarnate

  • Members
  • 5,039 posts
  • Bremerton, WA

Posted 24 September 2013 - 04:13 PM

 I'm not saying EFI is bad, I'm saying I want a carb. I don't care what others want, if they are happy with the EFI then good for them. I've done it, and made up my mind that I want to try a carb. Thank you

Op has had to say this far too many times.

 

The topic is carburetors.  No more talk about EFI, either pro or con.



#30 ivans imports

ivans imports

    1000+ Super USER!

  • Members
  • 2,950 posts
  • lumby bc canada

Posted 25 September 2013 - 09:25 AM

I love the SU stupid simple and one jet to change the thiner the oil the faster the response i ran su into a turbo for years worked realy good for pull thru setup. Was very easy to make work and tune but needed carb heat to keep from freezing



#31 Quidam

Quidam

    1000+ Super USER!

  • Members
  • 1,522 posts
  • USA

Posted 25 September 2013 - 12:05 PM

Phinzina wrote:

"I think it's going to have to be custom manifold to get what I want. That's ok, shouldn't be to hard to make.


The Holley website suggests a 390cfm carb for the 2.5l..."

 

 

I had the Holley 390CFM on my 1971 Datsun 510 ("Bluebird") with an L20B engine.  I had previously had a pair of Weber 40DCOEs (which gave me nothing but trouble), and the 390CFM was far superior for street use.  MUCH better fuel mileage, great driveability, and good power.  It was also MUCH more expensive than the average Holley 4-barrel.  Engine vibration ultimately destroyed an auxiliary venturi.  Sigh. 

 

Well, I don't know much about the LPG ring or conversion part and I would think some form of Webber would work out for you. On the Holleys, here's that 390 cfm. I agree, it's a good street carb. 6 cylinder Ford with an Offy intake comes to mind.

T2eC16VHJHwFG1Kcgw4BSOQOks8hQ60_1_zps94d

 

But what I'm wondering about is hood clearance. These drop bases will help there, even on a 2 bbl Holley.

T2eC16VygE9s7HI7KkBRuG2LK9g60_1_zps97c88

 

This 2300 series comes in 300, 325, 350, and 390. Probably more as there are several specialty carbs.

large0-7448_zpsf968077d.jpg?218

 

large0-80787-1ThrottlePlate_zpscf3b5d03.

 

Really, there is tons of mods you can do to these. Parts galore, boggles the mind really. That industry is fully mature and they're still making them. As far as cost, carb I would want for E85 would cost about $500.00.

 

Sealed throttle shaft.

large0-80787-1Seal_zps519e0e85.jpg?t=138



#32 Quidam

Quidam

    1000+ Super USER!

  • Members
  • 1,522 posts
  • USA

Posted 27 September 2013 - 11:08 AM

Ran across this, but those are 1 9/16" bores, dual line, double acc pump, mechanical secondary, base. Dude modifys them to fit, sells as remanufactured.

KGrHqFHJC8E85Do20BPZTz2u1gQ60_35_zps82b0

KGrHqMOKi8E1KOv3fBNZJ7Zuskg_12_zpse3e351



#33 Phizinza

Phizinza

    Yip yip

  • Members
  • 3,872 posts
  • South Australia

Posted 27 September 2013 - 04:31 PM

Have seen these, except I need to have petrol as well as LPG because not all service stations have LPG, especially in the Outback when 4WDing.

#34 Gloyale

Gloyale

    It's a sickness

  • Members
  • 9,469 posts
  • Corvallis, OR PNW

Posted 26 October 2013 - 05:46 PM

Figuring an average VE (volumetric efficiency) of 80% and RPMs up to 6500 I'm only getting a CFM of 228.  And that's a high VE, more like 70% on a stock engine.

 

Go crazy and assume 100% VE and 8000 rpms and you still barely get 350 CFM needed.

 

So a 390 CFM 4 barrel (style 4160, model 8007) would be WAAAY too much carb.........not enough vacuum to make the venturis work right.  My buddy has that carb on his jeep and it's too much for the stock 4.2 six cylinder.  (calculates needed CFM of 325)

 

I'd stick with a progressive 2 barrel like the weber.


Edited by Gloyale, 26 October 2013 - 06:17 PM.


#35 Quidam

Quidam

    1000+ Super USER!

  • Members
  • 1,522 posts
  • USA

Posted 29 October 2013 - 11:45 AM

Ivan said:" have seen a ea82 na with 4 barrel rx7 carb worked well reved to 8500 was neat trick"

 

Hitachi4BoreBustedTop_zps0afe2266.jpg

 

34_zps7dd49347.jpg

Hitachi 4 Bore, 28/32. Hell, I didn't even know anyone who knew about these befor now. Only things stopping me from using this is that it's so heavy, and I need a new top for it. Carb is good, got busted up in shipping or something. I have about $60.00 and time in it.

Hitachi4BoreSpreadBoreMazda_zps1030ff10.


Edited by Quidam, 29 October 2013 - 11:56 AM.


#36 ivans imports

ivans imports

    1000+ Super USER!

  • Members
  • 2,950 posts
  • lumby bc canada

Posted 01 November 2013 - 09:46 AM

why not use gm tbi unit from some kinda v8 or v6 give it signal from ej s injector pulse and try that out



#37 Phizinza

Phizinza

    Yip yip

  • Members
  • 3,872 posts
  • South Australia

Posted 01 November 2013 - 05:16 PM

Because i don't want an ecu at all and we didn't get anything like what that GM had here in Australia. I just and a simple carb..

#38 ivans imports

ivans imports

    1000+ Super USER!

  • Members
  • 2,950 posts
  • lumby bc canada

Posted 05 November 2013 - 10:14 AM

simple and carb Did you say that ! lol darn carbs no o2 to tune them. CFM wise a 350 -450 cfm carb about right a square bore carb. They make tbi units now that ecu injectors sensers all part of the tbi unit thats made to look like stock carb



#39 Gloyale

Gloyale

    It's a sickness

  • Members
  • 9,469 posts
  • Corvallis, OR PNW

Posted 05 November 2013 - 12:23 PM

simple and carb Did you say that ! lol darn carbs no o2 to tune them. CFM wise a 350 -450 cfm carb about right a square bore carb. They make tbi units now that ecu injectors sensers all part of the tbi unit thats made to look like stock carb

 

350 to 400 CFM for a 2.5 ltr  4 cyl?.

 

Like my math showed.....you'd need to achieve nearly %100 volumetric efficiency to need that much. 

 

 

(Cubic inches/2) x (Max RPMs/1728) x Efficeincy% = ideal CFM.

 

So 2.5 ~ 153 CU

 

 

(153/2) X (7000/1728) x 85% (generous...more like 75%  or less in stock form)

 

76.5 x 4.0509 X .85 = 263.409 ideal CFM.  Anything more than 300 will probably not run well at lower RPMs and may not idle/respond to throttle well.



#40 NorthWet

NorthWet

    Eeyore Incarnate

  • Members
  • 5,039 posts
  • Bremerton, WA

Posted 05 November 2013 - 02:13 PM

Sorry in advance for straying a little OT...

 

The 390 CFM Holley that I used on my 2.0L Datsun, although obviously having an excess CFM rating, had nearly flawless driveability.  Smooth and low idle, seamless transitions from idle to part throttle to full throttle. Definitely no stumble going to WOT (that stumble/jerk that so many people mistake as a sign of power as the engine recovers from the stumble), just a roar from the vacuum secondaries as they open and the smooth increase in power.  Mileage was in the mid 30MPG (US).  Carb had small primaries, vacuum secondaries, and was mounted to a dual-plane  mianifold (primaries/secondaries had separated runners to the head ports).  The only drawbacks were cost (carb was pricey) and durability (the carb shook apart after 2 years).



#41 el_freddo

el_freddo

    Eat, Live, Breath Subaru

  • Members
  • 517 posts
  • Lancefield, Vic, Aust.

Posted 15 February 2014 - 08:22 PM

Phiz have you looked into the stock carb from the ford 6 cylinders?  They look like they'd fit well, they're dime a dozen.  Apart from that I don't really know much more on them (as  you know I'm pro EFI - but understand what you're trying to achieve!).

 

It'll be great once you get it up and running - then the real fun beings!

Cheers

Bennie



#42 Phizinza

Phizinza

    Yip yip

  • Members
  • 3,872 posts
  • South Australia

Posted 16 February 2014 - 05:27 AM

That's the 34ADM Weber. What I'm considering using.

#43 monstaru

monstaru

    wow, relevance....

  • Members
  • 4,422 posts
  • OlyWa

Posted 16 February 2014 - 07:58 PM

Like I said, the fiat carb is the closest to what you'll want . :)

I did not write down my research, but i looked at all of these things years ago.

And just FYI, downdrafts have been done, not sidedrafts. Dean Loros was the guy who did them. Like 10-12 yrs ago now.
It was for his track car.
anyways.

34/34 dual barrel would lite right up proper!
cheers

#44 TOONGA

TOONGA

    I divided by zero

  • Members
  • PipPipPip
  • 120 posts
  • Australind

Posted 08 March 2014 - 08:21 PM

How about a 38/38 ?

 

http://www.ebay.com....=item1c313b4a60

 

TOONGA



#45 Phizinza

Phizinza

    Yip yip

  • Members
  • 3,872 posts
  • South Australia

Posted 08 March 2014 - 08:33 PM

I've heard Chinese rip off Webers are difficult to tune and act randomly. I've got a 34 now, and a rebuild kit, plus 8 or 9 jets which cost all up so far $80 or so.

#46 TOONGA

TOONGA

    I divided by zero

  • Members
  • PipPipPip
  • 120 posts
  • Australind

Posted 09 March 2014 - 01:51 AM

Cool I didn't look at the brand Just that it came up in the 38/38 weber search on Ebay.

 

Where did you get your rebuild kit? as the last one I bought cost 70 +dollars from Ebay and they wanted over 120 dollars in the shop.

 

TOONGA



#47 Phizinza

Phizinza

    Yip yip

  • Members
  • 3,872 posts
  • South Australia

Posted 09 March 2014 - 02:59 AM

Weber Performance in Melbourne. I picked it up while I was down there a couple of weeks back. $65

#48 el_freddo

el_freddo

    Eat, Live, Breath Subaru

  • Members
  • 517 posts
  • Lancefield, Vic, Aust.

Posted 14 March 2014 - 07:45 AM

I'm sure dad's got an RX7 carb from a rotarty 12B in the shed somewhere if you want to play with it - of course I'd have to talk with him about it first ;)

It seems that weber performance in Melbs has seen a bit of business recently - Tweety has just made a purchase there for his EA81 too...

Cheers

Bennie






0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users