Carb vs. EFI

wimpy98GT · Apr 7, 2008

I'm on the verge of doing a PI head swap on my 98 GT. I had been planning on going with the Trick Flow Track Heat intake, Comp Cams XE 278AH (the most aggressive cams they produce for the 2V as far as I know), and long-tube headers. But with Edelbrock coming out with their Victor Jr. intake I'm realizing that I can save about $1,500 by going with the Edelbrock and using a carburetor and slapping on shorty headers instead of the long-tubes (I already have a Mac off-road H-pipe and after-cat exhaust system).
Hot Rod made around 400 hp at the flywheel with a similar setup but a more mild cam, so I don't see why I couldn't make over 400 flywheel hp with my carbureted combo.

I'm just wondering if anyone has any insight on whether or not I could be losing any streetability or horsepower potential by going in this direction?

jprovence · Apr 7, 2008

When using similar combos, (head specs, cam specs, ect) a carb will almost always make more power then EFI. A carb does better fuel atomization. But much more senstive to weather conditions. Gets a little too cold on a particular day, then you have to rejet the carb. And poor fuel miliage is a false statement. The reason why cars got better milage was the switch from 3speed auto to 4 speed autos and smaller engines. Not carb to EFI. A properly tuned carb will do what an EFI does and then some.

Green&GoldGT · Apr 7, 2008

Scrap those ideas and stick with camshafts and an intake manifold that fit your powerband. You will lose alot of power from the Trick Flow intake on an N/A car. With the pistons in the NPIs, you are guaranteed to have piston to valve contact with comp 278s, as well as a loss of power down low in the rpm range. Stick with some comp 262s or 268s, pi heads and intake, and longtubes. Port and polish those heads if you want more power

Edelbrock's manifold is designed for big cams, ported heads, and high compression. So go with a combo that will suit your engine. The swap to an intake manifold with a carburetor is not a direct swap. Alot of modifications have to be done with emissions parts, throttle cables, and fuel pump just to name a few. Tuning a carburetor takes alot of time.

Winters98GT · Apr 7, 2008

nicely put, G&G GT.

Dont bother with that setup, and you dont need 278's. With stock PI heads, no need for anything more than a stage 1 cam. Ported, stage 1 or maybe a stage 2 cam.

262's are PI cams, 268's are NPI cams but work well with PI heads. More is not always better. Stock PI heads/cams/intake have been proven to go 12.40-12.60's with a good setup

Id personally go with the old VT(now under a new name, somebody will chime in) or Hitech cams, and stay far away from comp cams and their springs.

also, where are you coming up with saving $1500 from.

The NA mod motor seen has been well established as to what works, and what doesnt. I just got to work on my 3rd PI headswap, which hopefully will be done in the next week or two. Good luck

BurningRubber · Apr 7, 2008

Winters98GT said:
Id personally go with the old VT(now under a new name, somebody will chime in) or Hitech cams, and stay far away from comp cams and their springs.

Cushman Motorsports...

jstreet0204 · Apr 8, 2008

jprovence said:
When using similar combos, (head specs, cam specs, ect) a carb will almost always make more power then EFI. A carb does better fuel atomization. But much more senstive to weather conditions. Gets a little too cold on a particular day, then you have to rejet the carb. And poor fuel miliage is a false statement. The reason why cars got better milage was the switch from 3speed auto to 4 speed autos and smaller engines. Not carb to EFI. A properly tuned carb will do what an EFI does and then some.

A carb combo may make better "Peak" power, but EFI has a broader power curve. Carb combo can't make constant adjustments so how can it make better fuel economy. I grew up jetting carbs, but once you learn how to tune EFI, there is no comparison.
Here is a good article from some reputable sources on efi vs. carb.
http://www.carcraft.com/techarticles/carburetor_vs_injection/index.html

Mustang92 · Apr 8, 2008

Green&GoldGT said:
Edelbrock's manifold is designed for big cams, ported heads, and high compression. So go with a combo that will suit your engine. The swap to an intake manifold with a carburetor is not a direct swap. Alot of modifications have to be done with emissions parts, throttle cables, and fuel pump just to name a few. Tuning a carburetor takes alot of time.

Although I do agree on the first parts of the statement I don't on the carb tuning. If you are dealing with a rebuilt carb then maybe but most out of the box carbs do not require all that much tuning, mainly just jet changes and can be done pretty quickly if you know what you are doing. Just as fast as adjusting the tune in your PCM and reflashing.

Bill

wimpy98GT · Apr 8, 2008

Hey guys, thanks for all the help. FYI the PI heads I have are ported. The $1,500 I mentioned I could save comes from the fact that with a carb setup I would not need to purchase an ECU tuner, throttle body, injectors, etc., and since I already have an H-pipe that would work with shorty headers the shorty's would save me a few hundred bucks over full-lengths and an x-pipe or h-pipe.

jstreet0204 · Apr 8, 2008

wimpy98GT said:
Hey guys, thanks for all the help. FYI the PI heads I have are ported. The $1,500 I mentioned I could save comes from the fact that with a carb setup I would not need to purchase an ECU tuner, throttle body, injectors, etc., and since I already have an H-pipe that would work with shorty headers the shorty's would save me a few hundred bucks over full-lengths and an x-pipe or h-pipe.

Don't forget if you go carb, you've got to do something to handle the ignition. MSD makes a kit for 99 & up cop's that run's about $400. There is another company that makes an adapter to run a distributer off the cam gear, but I can't remember who right now. So you need to figure that into your cost. Also you aren't necissarily going to need new injectors with that setup.

wimpy98GT · Apr 9, 2008

Yeah, it's true i wouldn't necessarily need injectors, I guess I just always assumed with EFI I would eventually slap a Kenne Bell on it, so I just figured in bigger injectors

Winters98GT · Apr 9, 2008

wait, your going to slap a kenne bell on a high compression headswap car with stock internals?

wimpy98GT · Apr 10, 2008

oh god no. I just meant that if i stay with EFI it's going to be a longer, more expensive process. obviously on a 98 PI swap with 10.6:1 or so compression, forced induction isn't a good idea

98GTfromGA · Apr 11, 2008

wimpy98GT said:
I'm on the verge of doing a PI head swap on my 98 GT. I had been planning on going with the Trick Flow Track Heat intake, Comp Cams XE 278AH (the most aggressive cams they produce for the 2V as far as I know), and long-tube headers. But with Edelbrock coming out with their Victor Jr. intake I'm realizing that I can save about $1,500 by going with the Edelbrock and using a carburetor and slapping on shorty headers instead of the long-tubes (I already have a Mac off-road H-pipe and after-cat exhaust system).
Hot Rod made around 400 hp at the flywheel with a similar setup but a more mild cam, so I don't see why I couldn't make over 400 flywheel hp with my carbureted combo.

I'm just wondering if anyone has any insight on whether or not I could be losing any streetability or horsepower potential by going in this direction?

the 278 cams won't work with stock pistons....you'll need them flycut

Carb vs. EFI

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