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Dual Carb?


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19 replies to this topic

#1 [HTi]Johnson

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Posted 02 February 2005 - 11:00 PM

What's stopping me from running two carbs...one on each intake port? I know there is coolant lines running through those? ANy tips/shoot downs/incouragement?
[HTi]Johnson

#2 85Sub4WD

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Posted 02 February 2005 - 11:23 PM

Umm ......
Why don't you cut your carbs and go with FI?

It's quick, easy, and reliable.

Some of the Austrailian / New Zealand cars have twin carbs - get an intake manifold from them and save yourself the trouble.

#3 BobBrumby

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Posted 02 February 2005 - 11:31 PM

heh short of fabin up a manifold including theremostat stat and water cross over i dont like your chances. I think you need a connection bettween the two ports as this is what i have seen in stock and ram performance configuration. On the pic I saw they used some rubber tube between the ports and was approx. the same size at the pcv hose but a little bigger. There are stokc dual carb manifold but they are rare. As 85sub said go efi as its gots more power economy drivability n such. I believe you have an ea81 and a spfi fron an ea82 car will bolt on wiht minor mods. Theres a writeup in the USRM - Repair and Mod section, the button is at the top of each page ;). Even easier is a 32/36 webber and gives you almost the power of spfi but a little less economy.

#4 Ross

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Posted 02 February 2005 - 11:43 PM

Hey, I say go for it. It is something that i have often thought about. There would be some fabrication involved, but nothing too extreme.
You would need to make a water cross over (I think) and set up a thermostat. The thermostat could be easily made using a gm one that comes with the housing. You'd just need to make a backing plate for it.
Those intakes are just screaming to have a carb each!

#5 [HTi]Johnson

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Posted 03 February 2005 - 12:24 AM

Hey I looked into the SPFI conversion...on the USRM and the link is dead.
What carbs should I use? What is the simplest? Two Webers 32/36s or the equivelant to half (since it is splitting the intake by half)
[HTi]Johnson

#6 Craven

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Posted 03 February 2005 - 02:13 AM

These guy's sell a dual carb kit. http://www.ramengines.com/index.html

Not cheap, but they are getting 100hp using it with other mods.

A guy could build one of his own for a lot less money.

#7 Roobaflu

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Posted 03 February 2005 - 03:03 AM

These guy's sell a dual carb kit. http://www.ramengines.com/index.html

Not cheap, but they are getting 100hp using it with other mods.

A guy could build one of his own for a lot less money.


saw the kit listed for a grand, too bad no picture of it though

#8 MilesFox

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Posted 03 February 2005 - 03:12 AM

what about a dual spfi using 2 maf, 2 tb and one distributor? with teh maf separate each side will have poper mix proportionate to airflow, 2cyl instead of 4

#9 85Sub4WD

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Posted 03 February 2005 - 08:24 AM

That is an interesting idea, I would be interested to see how it worked.
A MPFI intake manifold/heads would work better for this kind of project because there already is a coolant bridge on the manifold, and there is a better intake setup. (larger diameter)

These guy's sell a dual carb kit. http://www.ramengines.com/index.html

Not cheap, but they are getting 100hp using it with other mods.

A guy could build one of his own for a lot less money.


Did anyone else notice the Fram oil filters on the engines :eek:

#10 [HTi]Johnson

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Posted 03 February 2005 - 08:40 PM

Where can I find the conversion info? to SPFI
[HTi]Johnson

#11 85Sub4WD

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Posted 03 February 2005 - 08:52 PM

I saved a copy to my computer, which I can email you.
I tried the link myself and it worked, so I think you may have an issue with your web browser.
PM me and I can email you the manual (it is over 3Mb, so make sure you can handle it).

#12 NoahDL88

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Posted 03 February 2005 - 08:56 PM

2 mafs and 2 tbs will run way, way too rich, the car would be running so far out of its stock parameters that the computer would not be able to compensate, maybe running half fuel pressure could make up for this, but i just don't think it would work

#13 85Sub4WD

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Posted 03 February 2005 - 09:02 PM

2 mafs and 2 tbs will run way, way too rich, the car would be running so far out of its stock parameters that the computer would not be able to compensate, maybe running half fuel pressure could make up for this, but i just don't think it would work

ditto on that
The SPFI system is simply not that flexable.
I bet that if anyone hacks the ECU, we could get a LOT of power out of it just by piddling with the programming.

#14 Ross

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Posted 03 February 2005 - 09:08 PM

2 mafs and 2 tbs will run way, way too rich, the car would be running so far out of its stock parameters that the computer would not be able to compensate, maybe running half fuel pressure could make up for this, but i just don't think it would work


What kind of signal does the injector recieve fron the computer?
maybe a better idea would be to build a circuit that will 'split' the signal to two injectors, ie if it is a DC pulse signal, one injector could recieve every second pulse, the other receives the next???

#15 85Sub4WD

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Posted 03 February 2005 - 11:01 PM

It would probably be easier to build/buy a different fuel control unit and slap that on.
I am at present (somewhat) trying to crack the TBI computer but with no luck.
All programming is done in C and that is a pain to mess with, and I still have not figured out how to read the PROM on the circuit board.
If anyone has info I would appreciate it.

BTW - for those with 87+ turbos, if your computer was hacked, it would be possible to totally eliminate the fuel cut system, and maintain otherwise normal performance without messing with anything else.
Just a thought ...

Are all of you forgetting about MPFI N/A?
Just put bigger injectors in and use a spider manifold with an XT6 TB
Better airflow and better performance - just have to swap the cylinder heads.

#16 sheppie62

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Posted 03 February 2005 - 11:27 PM

How about VW carbs, Dual 40mm Kadrons, IDFWebers, Porsche 356 Zeniths 32NDIX's

#17 Ross

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Posted 03 February 2005 - 11:52 PM

Or you could put a horizontally opposed porsche engine in!!:brow:

#18 85Sub4WD

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Posted 03 February 2005 - 11:53 PM

The first real upgrade you could do is to swap the heads with MPFI heads.
The stock SPFI/Carb heads do not allow as much airflow in/out as the MPFI heads; therefore you would be limited as to the amount of upgrading you could do by the amout of airflow available.

How about VW carbs, Dual 40mm Kadrons, IDFWebers, Porsche 356 Zeniths 32NDIX's

These carbs may all work, and would be upgrades, but carbueration is inherently inferior to fuel injection because carbs put resistance on the incoming air to allow for the venturi to dispense/mix gas in it.
Fuel injection systems cram as much air into the engine as they can and meter the fuel to match, based on sensor input.
Therefore, because it allows for more air to enter the combustion chamber, and because it can match that additional air with additional fuel, fuel injection is superior.

Tho still a flat four, a Porsche engine would be cheating :-p

#19 ballitch

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Posted 04 February 2005 - 12:40 AM

are you telling me that when i wanted to rebuild my EA82 motor all i had to do was email ramengines.com and get my rebuild kit, without going through all this trouble of a ej22 conversion, i would have made a BIG mistake by doing that, cant deny 60 extra horsepower. just too darn tempting.




~Josh~

#20 85Sub4WD

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Posted 04 February 2005 - 01:02 AM

are you telling me that when i wanted to rebuild my EA82 motor all i had to do was email ramengines.com and get my rebuild kit, without going through all this trouble of a ej22 conversion, i would have made a BIG mistake by doing that, cant deny 60 extra horsepower. just too darn tempting.

Pretty much, but ramengines.com is mainly geared toward aircraft which operate for long periods at a particular rpm, so I don't know how well some of their kit would work on cars, but much of it would be very useable.




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