Carb or MPI

[Roehm]

Hello all,

I am going to start an NA build for my 94' Shadow ES 2.5/5-spd. The real big question here is I need to know weather I should go MPI or Carb. This is not going to be a track only car, it will be my daily driver also. I am shooting for a 150+ hp range and I already have a good idea of what I want to do but I will get into that crap on another post.

If I do MPI I will pull the wiring harness and comp out of a 91' Sundance RS. I don't know if that will be a direct drop in or not. Or I could go with a carb set up also know nothing about what you need to do that. I like carbs a little easier to tune in my opinion but I want to hear what you all think.

Thanks

Peace,

[ZoskalonMPI]

I don't think you can easily put the 91 harness and ECU into your 94. You'd also need to change your body computer for sure for the 91. There was a data bus change in 92, so <91 speaks a different language than >92. Of course its doable, just not sure of how much work is in store. MPI I'd say is the way to go, much better flowing manifold than the carb one I believe, and making power on N/A is all about better flow. But tuning is tricky, if you went MS, then life'd be easy.

[capev86]

carb will not be street legal on a car that came with fuel injection.

mpi is the way to go. batch fire tuned properly will be marginally more efficient than tbi and the turbo/mpi intake manifold will outflow the tbi unit. or you can find a 92+ mexican donor to get the correct harness and computer out of (remember 2.2 vs 2.5 and especially auto vs. 5spd)

[Roehm]

Yeah I suppose MPI will probably have to be the way to go. But the thing is I am no where near Mexico so I be the chances of finding a Mexican donor car are pretty low. Also I don't understand why the Carb. would not be street legal, I don't have emissions to worry about in my state or is it something else that I don't know about.

[capev86]

then you are probably ok in regards to emissions....

[Roehm]

Yeah, I just don't know what to do I am still split on the deal. Which ever one would be easier it doesn't really matter.

[dodge78]

Here is a carb for you.

eBay Motors: NEW 78 79 DODGE OMNI PLYMOUTH HORIZON CARBURETOR (item 290178217962 end time Nov-11-07 19:38:39 PST)

[Wizard]

Don't recommand it either.

I suggest EFI or Weber carb (32/36 DFEV) with small work on linkage salvaged from junk holley 5220/6520. Parts for Weber are still available and jets kit can be ordered.

For obtaining weber carb 32/36 DFEV go Ebay. Average price 60-120 usually and many of them are low miles, even the metal work is still fresh and shiny! I obtained one this way.

I drive daily my 1987 caravan carbed (Holley 5220) 2.2L. Holley carb is really worn out yet still going ok thirstily since I had to rebuild that poor carb 3 times. I've ordered the weber parts and weber carb and waiting for them to arrive as I speak.

Cheers, Wizard

[Roehm]

Yeah that carb. idea does sound like fun. Does anyone know what I will all have to go through to do a carb. swap? I don't want to remove the factory electronics if I don't have to. I still want to use this car as a daily driver.

[Wizard]

This is the beauty of this weber carb swap.

Just be aware about the throttle closed contact and throttle kicker. The weber have bosses that you can use if you want.

Cheers, Wizard

[Roehm]

So do I still need to swap to the VW dissy or can you use the stock one? I would imagine you have to. Also aren't webers kind of expensive to do the swap?

[dodge78]

The ebay one is holleys copy of the weber. The best part is no screwing with linkage, its all ready there.

[Wizard]

Don't understand what I have been trying to say is that can still use the stock stuff (ignition is untouched). Use the Weber or another correct 5220 carb with throttle shafts bushings replaced or low wear. Do you want to trust their words that 5220/6520 carb is good? I got 3 5220 and 6520 carbs all are not suitable due to throttle wear from ebay. What more, that 5220 on that ebay is incorrect because of carb is different, look at the round black rubbery looking with 3 holes and 1 smaller holes near the emission vapor recovery nipple? That's how I tell. The correct ones have metal cover with 3 screws in that place (blanking) and no diaphgram.

Another reason is that weber is you can re-tune it with jet kits and throttle wear is not a problem as they are very low miles or can be had new. Rebuild kit is available.

About the shaft wear on 5220/6520 carbs is that I have tried few carb rebuilders and they will not touch these or say they only sell rebuilt units by third-party and use your as core (means grabage rebuilds) and lot of them will not have shaft bushings rebushed.
The one I got was a rebuild and throttle bushings were not repaired. Just a friendly warning. I was lucky to find a okay 5220 in 2004 from local friendly garage.

Symptoms of worn out bushings on throttle shafts is rough idle, poor MPG, missing, hard to pass emissions, high rpm idle that cannot be bought down low enough to some point affects drivabilty and hard to tune/ diffcult to set up ignition timing. Including hard starting.

Also I cannot use 6520 carbs as they were not mentioned clearly enough in ebay because this requires O2 sensor and computer to utilize this. My caravan is canadian and only use 5220 carb, no O2 sensor.

Cheers, Wizard

[Roehm]

Sorry sir I must have over look it when you said I didn't need to change my ignition system. I thought you had to because I heard other people say something about it. So I suppose I just need to get a weber carb and a carb intake manifold so I can get rid of my tbi crap. You have any recommendations for an intake manifold?

Thanks

[DaytonaTurbo87]

MPI efi will work, but it is a ton of labor to get working properly. A carb will be much easier, go with a weber like suggested.

All you have to do is leave all your stock electronics in place. Remove your efi intake and unplug the throttle body. Bolt up your carb/intake and a new fuel pressure regulator and go. The computer will still think it's efi, however without the throttle body there, all it's doing is controlling the ignition timing curve, and doing a much better job of it than any aftermarket distributor will.

If you don't have emissions checks, then don't worry, swap away and go for it. Lots of 80's mustang/camarobird guys ditch efi and go to carb.

If you're on a real tight budget and building a n/a ride, carb is better than efi, and certainly better than efi with a stock computer. If you're going to run an aftermarket engine controller, like megasquirt, fast, sds,etc then multiport injection is the way to go.

A wideband o2 wouldn't be a bad idea either, but you can do without it if you must.