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Carb 4 Port VS FI 6 Port

Old 07-08-04, 10:35 PM
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Carb 4 Port VS FI 6 Port

Im currently racing an NA FC In Rally 2wd Open class. Engine modifications are unlimited but my budget is severly limited.

I have an engine rebuilder that is willing to build me either a 4 port carb motor or a 6 port FI. He admits he doesnt have much experience with FI motors but insists he can get more power with a 4 port than a 6 and that carburetors are the way to go.

What would you do, and why?
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Old 07-10-04, 07:08 AM
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Either way, FI or carb, the four port mortor is the better choice.
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Old 07-10-04, 03:55 PM
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Take the four port .
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Old 07-13-04, 03:52 AM
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I really am liking the ports on my new EP motor.. However..... Unlimited potential...... Hmm

Have to agree.. with one caviat..

4 Port Motor ported silly.. and FI. It is out there for the right budget.....

As you have a limited one.. Yep.. 4-Port.. Carb. Simple.. Much power. AND If your Tuner is real good with Carb/4-Port setups.. you will be fine in mid range/partial throttle areas I am sure you need when drifting around bends etc.. where throttle response is critical.

A Poorly tuned FI will kill you in rally type events where you (SHOULD) be at the edge of control I would imagine..
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Old 07-13-04, 09:25 AM
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Originally posted by SPiN Racing
A Poorly tuned FI will kill you in rally type events where you (SHOULD) be at the edge of control I would imagine..
The same could be said about carbs. But FI will compensate for altering conditions better (altitude, temp, etc.)
I still vote for a SP with an AFC on top of the stock FI system to keep it simple, cheap, and reliable.
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Old 07-13-04, 03:22 PM
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That may be true.. but you need to see where his builder is not familiar with FI... sooo The tuning issues may be issues.
Also I think having a lot of timing control as in stand alone gives you a lot of performance in addition to just adding fuel.
But I digress.... My personal thought is kinda clear.. go all out FI.. But in his case his tuner is a carb guy who I gather is good at it.. Sooo Go with a Carb setup.

Having a Motec would rock... if you had a Motec tuner, or knew how to get the most out of it yourself.... If you dont.. or cant.. Go with what you can get the most performance out of yourself.. or your tuner optimally can get the most performance out of... and call it a day.
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Old 07-14-04, 12:03 PM
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now when you all say 4 port is better, your talking about the 4 port out of a first gen right?
i mean i know there is a 4 port in the TII, and a 4 port in the 3rd gen, but since he is running no turbo, then those engines would do no good since they have such low compression right?
no of course most first gens came with a 4 port 12A right?
so the engine of choice in thise case would be the rare 13B 4 port (obvioulsy non turbo) engine out of a first gen?
is all of this a true statment?
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Old 07-14-04, 12:04 PM
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now when you all say 4 port is better, your talking about the 4 port out of a first gen right?
i mean i know there is a 4 port in the TII, and a 4 port in the 3rd gen, but since he is running no turbo, then those engines would do no good since they have such low compression right?
no of course most first gens came with a 4 port 12A right?
so the engine of choice in thise case would be the rare 13B 4 port (obvioulsy non turbo) engine out of a first gen?
is all of this a true statment?
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Old 07-14-04, 03:46 PM
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No not really..

Basically since his mechanic says he will build him a 4-port.. that would indicate using the 4-port housings from a 12A that can be used on a 13B.. and basically you take the 13B eccentric and rotors and install it in a motor made with 12A steel housings.
Then you have a 13B 4-port.
Why use the steel housings off a 4-port motor?? Cause you can make much safer uniform ports that are of the size you would want.
When porting the 6-port you may have soemwhat more radical timing on the 5/6 port area, but the primaries are fairly small.
You cant use the 12A intermediate housing because there is no provision for the Injectors.
Therefore you use the 12A style 4-ports with the 13B recip assy.. and voila 13B 4-port.
Simple and effective..

You can get exotic by using different housings etc.. there are a LOT of options through the years of housings that I wont get into.. but you get the gist...
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Old 07-19-04, 05:36 AM
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I would think that maybe a full bridged 6 port would be pretty kewl. Ito has had pretty good luck running those on the stock computer.
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Old 07-20-04, 08:26 PM
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And if you need a good throttle response, SU carbs are much easier to setup, as all you need is ONE needle, and you're done (spring and oil are the same on virtually all setups)
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