I'm thinking about installing an aftermarket fuel injection on my 427 BB. Both Holley and Edelbrock seem to make interesting looking systems.

Throttle body systems seem to be a lot cheaper than multi port systems. My question is, are multi port systems worth almost double of price of throttle bodies (in the case of Holley). My engine makes about 450 hp, but it is only street driven and not raced.

Thanks,

Jari

I prefer the multi port units over the throttle body units. They both use throttle bodies, but the injectors are in the throttle body on the TBI systems, versus in the manifold next to the port on the multi port systems. For the money the Holley 950 Commander MPI is the best bang for the buck in my opinion.

The multi-port units allow more growth if you decide to further modify your engine later. Virtually all the manufacturers have gone away from the TBI setups to the MPI ones. I feel they're smoother, more efficient, better mileage, and more adjustable to changes.

Jody

from what I hear a tbi cant support over 400 hp smoothly

TBI is pretty restrictive when you start talking much over 400hp. I would lean towards the MPI myself.

-Joe

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79' Z28 4-spd- built 355, TRW 10:1 forged flat tops, WP SportsmanII heads, Crane Energizer 230/230 duration .480"/.480" lift, Edelbrock Victor Jr., Holley 750cfm, Dynomax headers, dual 3" flowmasters :) 3.73 Posi 10-bolt

what about the Big block ramjet from accel? i bet that would be sweet.

I think that the multi-port systems are actually dry systems b/c they inject the fuel very close to the valves. Whereas the TBI units are really just electronically controlled pressurized carbs.IMHO.

TBI's have all the wet air flow air/fuel distribution problems that plain old carb's have but at more cost. But I haven't checked prices between a SOTA carb. and intake system vs a new TBI. unit. I might be supprised?? pdq67

pdq is right. The TBI isn't much of a change over the carb setup. The MPI is the way to go. You're only dealing with dry flow until just before you get to the intake valve. This provides you with a well atomized charge just at the inlet of the cylinder. The MPI is very easy to work on also.

Thanks for replies,

This helped me to make the decision towards the MPI, although it is a lot more expensive. But anyway it looks a lot better too.

Jari

I hate TPI. If you ever have the misfortune of flooding an engine equipped with this disasterous piece of technology, you are basically hooped for several hours, especially in cold weather. If it floods, the stupid TPI just keeps on pumping in the fuel as you continue to turn the engine, flooding it even further. It is realistically just a poor shot at a glorified carb anyway. Go with MPI, you will be much happier.

you can pull the electronics this lets you clear it out http://www.camaros.net/forum/wink.gif

BreathWeapon,

Ya might not know this but, most any "good" fuel injection system (TBI or MPI) has a "clear flood mode".

If you hold you foot to the floor while cranking the engine, the ECU should stop pulsing the injectors for a while to clear the flood condition. http://www.camaros.net/forum/smile.gif

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Paul D.

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68RS, 331, 10.5:1, 4spd, 3.90 9", lowered, 245-45-16's all 'round

One would think so, but it doesn't seem as though GM thought of this as early as 1985 on their TBI units. Sure you can pull off the electronics, which is what we did, only to recieve terrible frost bite on our ungloved hands (you can't work with massive gloves on too well). Before this, even with or without the pedal depressed, we could see the injectors keep pumping the fuel into an already flooded engine http://www.camaros.net/forum/frown.gif . Since it was 35 below, the fuel would not evaporate either, so we had no choice but to "operate", so to speak, and disengage the injectors. A far cry from the simplicity of using a pen to keep a carb choke open.

[This message has been edited by BreathWeapon (edited 11-27-2001).]

He, He!!!

Love the pen. No, you are supposed ta get your simple minded buddy ta stick his head over the carb, while holding the choke open and crank until she backfires up through the carb. Thus singeing (sp??) his hair!!

Been there, done that!!! He, He!!!, boy does that bring back memories!

Cheap 89 cents a six-pak beer, 25 cent gas and $250 cars!!! pdq67

Heh, yup, done that too, right outside a bar at night. The flash and the noise was enough to make all the patio crowd "ooh and ahh", but I was not so amused http://www.camaros.net/forum/biggrin.gif

LOL's, LOL's!!! pdq67

weird, i did it and it didnt keep spraying weird but mine is a 88 350

[This message has been edited by c4boom (edited 11-28-2001).]

I suppose there also may have been something stuck/plugged with minute ice crystals from the cold weather, and this may have been why the injectors would not shut off. Either way, we were not happy to say the least, and would have killed for a carb right about then, hehe. http://www.camaros.net/forum/biggrin.gif