2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

carb Q for 2nd gen

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Old Nov 7, 2006 | 09:14 PM
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carb Q for 2nd gen

Can i use any double pumper / four barrel holley carb on a rotary? Are they easy to rebuild. is there site on the net which describes rebuild process?
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Old Nov 7, 2006 | 09:36 PM
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Why are you wanting to run a carb anyway? They are inferior to EFI in basically every way.
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Old Nov 7, 2006 | 10:09 PM
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why is that? with holley you can make same hp as tuned efi
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Old Nov 7, 2006 | 10:11 PM
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i dont trust my 20 year old fuel injection
carbs are still being used on street and race track on 13bs and 12a. i think it it m ore reliable and dont need no laptops to tune.
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Old Nov 7, 2006 | 10:20 PM
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First off, what are your goals? If its for a street car, then there is no reason to go carb. You will lose power at some point over the rev range, whether it is low end or top end (probably low end) and probably wont really gain any power unless it has a major port job. Sure you don't need a laptop to tune it, but that means you will never have as good of a tune. It also has no control over spark like EFI system do. There is a reason that no cars use carb setups anymore - because they just aren't as good. Basically the only reason to use a carb is if you're too cheap or too lazy to mess with fuel injection, and the too cheap only applies to extreme porting.
As for your "20 year old fuel injection" there is likely nothing wrong with it. Get the injectors cleaned and replace any cracking lines and your good to go.
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Old Nov 7, 2006 | 10:30 PM
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why do you think fuel injection was developed? low emissions and fuel economy. auto companies were pushed by rules a regulations.
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Old Nov 8, 2006 | 12:25 AM
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Originally Posted by rx7vadim
why do you think fuel injection was developed? low emissions and fuel economy. auto companies were pushed by rules a regulations.
You are dreaming.

As a hint... on a non turbo rotory... better fuel economy (leaning out of the engine) results in more power.

If carbs are so great why do they make retrofit FI kits for old GM, Ford, and Dodge V8 motors, that typically give you an extra 15% increase in power as well as simular gains for fuel economy???

A carb is inferior to any fuel injection system on a street driven vehicle.

and why did you feel the need to start a 2nd thread on this???
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Old Nov 8, 2006 | 12:37 AM
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Originally Posted by rx7vadim
why do you think fuel injection was developed? low emissions and fuel economy. auto companies were pushed by rules a regulations.
And why do you think that every single racing car that isn't bound by either money or regulations uses fuel injection?
Hint: it gives more power
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Old Nov 8, 2006 | 12:41 AM
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Originally Posted by rx7vadim
why do you think fuel injection was developed? low emissions and fuel economy. auto companies were pushed by rules a regulations.
AHAHAHAHAHAHAHA....
that made me laugh so hard.
all the F1 cars are running carbs... *rolls eyes*
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Old Nov 8, 2006 | 01:09 AM
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So If I Install A Holley Carb On S5 I Will Loose 15% In Hp, The Engine Would Make 135hp, I That What Ur Saying Ice Man
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Old Nov 8, 2006 | 01:10 AM
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i love my 650 doule pumper and will never go back
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Old Nov 8, 2006 | 11:57 AM
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So If I Install A Holley Carb On S5 I Will Loose 15% In Hp, The Engine Would Make 135hp,?????????????????i dont think so
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Old Nov 8, 2006 | 12:19 PM
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Originally Posted by rx7vadim
So If I Install A Holley Carb On S5 I Will Loose 15% In Hp, The Engine Would Make 135hp,?????????????????i dont think so
Don't think you read my post. Go back and read it again.
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Old Nov 8, 2006 | 12:26 PM
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also a double pumper is only suited for a large ported motor, it would drown a stock motor. the CFM of a carb needs to be taken into effect whenever tossing a carb onto an engine so you have to meet the airflow/fuel needs of the engine.

so yes, Mark is right that if you toss that carb on there i would expect you would be losing power, might make it back up top but i can almost guarantee it won't be the same car out of the hole.
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Old Nov 8, 2006 | 01:01 PM
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If it's an S5, removing the EFI also kills the VDI... I'd wager that's a pretty big loss even if the carb manifold has much shorter runners...

And it would run like poop.

Megasquirt = $200
Carb = >$200

It's a no brainer.
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Old Nov 8, 2006 | 01:49 PM
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Like I said in my post, you might be able to get the same peak power with the right carb manifold and the right jet, but you would not have the same power on the low end, which is bad for a street car.
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Old Nov 8, 2006 | 06:17 PM
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what about extra stuff for magasquirt. add $150
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Old Nov 8, 2006 | 06:21 PM
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What extra stuff?

A little bit of wire, but most people should have that already. If you want to do things nicely you would make a new wiring harness with it's own fuse box, but that's only about $25 worth of extra stuff...

Keep in mind that the carb requires a new fuel pump, regulator, ignition system, etc.
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Old Nov 8, 2006 | 06:47 PM
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do u need relay box, usb cable, intake temp sensor
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Old Nov 8, 2006 | 06:53 PM
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2 relays (one for the 'Squirt and one for the fuel pump), and the intake sensor is already on the car.

You only need a USB cable if the laptop doesn't have a serial port.
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Old Nov 8, 2006 | 07:40 PM
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Originally Posted by Aaron Cake
You only need a USB cable if the laptop doesn't have a serial port.
These days most of them don't though. But a usb cable is super cheap.
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Old Nov 8, 2006 | 09:27 PM
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anything that costs less than a tank of gas really cant be taken seriously as an expense.
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