Dual Carb vs. FI

[Leesfer]

I am new to engines, so could someone help me out with how these two work and which is better (aka more powerful)?

And if the carbs are better then is it possible to convert an engine from FI to dual carb?

[So Cal Mark]

sure it's possible, but not legal in Calif for your car

[Leesfer]

Does having it carbed make enough of a difference for me to be sad that I have an fi rather than a carbed spider?

[mdrburchette]

I would think the only reason you'd want dual carbs is if you were planning to build a performance engine. The stock FI would restrict any performance tuning. If you were leaving the engine stock, I'd probably lean toward the FI since it's more user friendly and you've already got more hp than most of us with carbs.

[Leesfer]

I am building a performance engine... 9.1.1 pistons goinging, one of marks snake headers, free flow exhaust and free flow cold air intake, race cams, valve springs

Is there anyway I can have the FI be less restrictive?

[bandit]

Sure you can make anything better it is just a matter of your ability through custom work
to make the needed changes . On the Stock FI Manifold the throttle body is to small the
flow is restricted just enough to feed a stock 2L Fiat . If you were to change the ECU
to a Mega Squirt or after market system like Haltech, Tec3 from Electromotive or some
other brand you can custom tune your FI but the next thing needed is more Air Flow so you have
2 Main options either goto dual carb after market manifold and IDF or Side Draft throttle Bodys
or the other option would be to turn the top half of the manifold around cut off the Throttle
Body and weld on a larger TB . I have look into this and the manifold does almost bolt up in
the 180 position perfectly except for a few spots that have gaps that would need to be welded
and filled in . The ideal i had was to use tubing with a bend at maybe 45 or 70 angle on it to
face toward the front of the car . You would pretty much be replacing everything on the FI Fiat
but the fuel pump .

If you went with Duel Carbs you would save some money up front but find buying jets and the need to
re tune the carbs down the road from time to time a hassle . Mega Squirt seems to be a reasonable
route to go . The throttle bodys run about the same price as carbs Weber has a Kit with injectors
for about $600.00 .

[Danno]

Temporary hijack---
Bandit,
do you own a suzuki aerio? just a coincidence I'm sure, but on the aerio forum I hang out on there is a Dan with the screen name Bandit.....

Now, back to your regularly scheduled Carb vs FI discussion....

[bandit]

Hi Danno

No i don't go to any other import site other then Italian in nature Bandit wasn't a nic i really wanted i
just got tired of trying to find something i liked lol everyone beat me to the names i wanted .

When will you finish your tail lights i am interested in the your project ?

[Danno]

Hi Danno
When will you finish your tail lights i am interested in the your project ?

Lol, I wish I knew. I'd like to have the bodywork done (including lights) by the MOFLO meetup in early June. We'll see about that....

[racydave]

Maybee Ill see you at MOFLO? Im tryin to talk some locals into goin with me, but, Im goin! Intreuption over...

[pope]

Leesfer,
I want to know what YOU think performance is?
The standard F.I. Spider is stock at 102 hp. If I told you I could get you to 135hp would that be enough? Also, the throttle body of the spider is 55mm and can produce about 320cfm. The spider as is only needs 170 cfm, so it is not dying of air starvation as alot of people think. In fact its not even close.
I wouldnt go higher than 8.5:1 or 8.9:1 pistons. Forget about the cams, not worth it and can cause EFI problems. Also, the exhaust on the FI spider is not restrictive anyways, ( if state restrictions allow,the cat convertor could be tossed) it will do just fine. I would put on a rising-rate fuel pressure regulator and boost the pressure only about 4 PSI, thats it! Also you'll have to have the head flowed and ported with the manifolds.
You now have what the turbo spider gave you without the turbo or lag.

[mbouse]

sure it's possible, but not legal in Calif for your car

not being a resident of the smog-law capital State...i'd like to ask a question please.

is it illegal to place a perfectly good mechanical replacement 1800 engine into a blown '82 FI engine bay? Can only the '82 engine replace a worn out '82 engine, and therefore meet '82 smog laws?

if that is so, yeash!! Michigan winter just became more tolerable. BTW-in case you are wondering, it was +7 F here this a.m.

[STP]

"I want to know what YOU think performance is? The standard F.I. Spider is stock at 102 hp. If I told you I could get you to 135hp would that be enough? I wouldnt go higher than 8.5:1 or 8.9:1 pistons. Forget about the cams, not worth it and can cause EFI problems. Also, the exhaust on the FI spider is not restrictive anyways, ( if state restrictions allow,the cat convertor could be tossed) it will do just fine. I would put on a rising-rate fuel pressure regulator and boost the pressure only about 4 PSI, thats it! Also you'll have to have the head flowed and ported with the manifolds. You now have what the turbo spider gave you without the turbo or lag."


Hey Pope,

Are you saying that you can increase the output to 135 HP by putting in 8.9:1 HC pistons, increasing the fuel pressure slightly and doing some work on the head? I have been considering having my engine rebuilt and putting in HC pistons but I did not know what kind of HP improvement that I would see.

Also, does anyone have recomendations on what brand of pistons to use or stay away from? I read somewhere that Kolberschmidt is a good brand.

Thanks,

Steve

[bandit]

mbouse

If your using the FI i don't see any issues .

[pope]

I glad that you did not say "Thats all I have to do?" Because that is a lot of work. Do not put high compression pistons in a FI Spider. No more than 8.9:1 (they are slightly higher compression but not High Compression Pistons). See if you can t find some one who has then laying around and will sell them, no need to buy them new. Cast are perfect and Forged is complete nonsense for your use. Lots of work is needed for smoothing the ports and combustion chambers and getting the flow matched.
Stock injectors are fine for that HP.
Also, not just raising the fuel pressure slightly, but a rising-rate fuel pressure regulator, like a BEGi model, for instance.