carb'd 308 to fuel injection; interest?

For the Carb'd 308 GT4, GTB and GTS owners;

IF a fuel injection system was available which allowed you to fully tune (including ignition timing) the ECM using a PC, came with DIS (controlled and operated by the same ECM), used parts which were available from any major parts house (in stock) including the DIS, allowed for an off the shelf NO2 kit (for those who want NO2) to be installed without any mods, and could be tuned for forced induction (and was set up to accept standard type inlet duct so as to ease the addition of forced air induction)...

1. would you be interested?

2. what would you consider as a reasonable cost?

 

my time to get on here and respond is limited due to other restraints (work and family specifically) so my replies will be periodic.

I too wanted the carb'd 308. I liked the sound and knew that all in all the rebuild kits were cheeper than fuel distributors for the CSI units.

As time has went, and after reading several things about power increases due to forced air I wanted to increase the power output of my car. I also realized the limits when it came to forced induction and carbs. especially multi carbs.

that coupled with my trip to the mountains (I live at sea level). the carbs were horrible high in the mouintains due to their in ability to self adjust to changing altitudes.

The design criterias were simple,

completely programable with a laptop (ECM = Electronic Control Module, or the computer)
full fuel and ignition timing control via the ECM so as to control boost knock,
Completely reversable so that as time went, and value went up, I could if I wanted put the carb's back on without having gaping holes, etc.
the last design criteria was that it could be installed easily, buy a novist in their yard without major tools.

the Carb's 308's have a very short intake which the carb's bolt to. the carb's act as the rest of the intake runner. this intake setup is not the same as the 2V and 4V FI models. From the way that I have designed the intake manifold assembly I believe that most if not all of the sound will stay. that is atleast the desired effect. I will keep you posted on that. also, I have eliminated the sencronizing issues of multiple throttles.

There have been lots of talk about forced air induction on here lately and all of it revolves around the CSI units. the carb'd units are out in the cold unless they want to invest in EFI first. I do not know of a straite forward EFI conversion available that is not excessively expensive. then, you facture in the cost of the Supercharger kits, etc, and it leaves the carb'd guys out. I want to change that. I have been engineering this unit with Supercharging it as a final stage design. Also, I am using GM parts which will allow for easy and inexpensive repairs and upgrades.

The only non-reversable thing that I see will be the required hole for the wiring harness. this will be out of sight, and I will try and make it as small as possible.

I am at the final fabrication of the manifolds. some milling is all that is left. once I have worked out the gasket issue, I will have the fuel system to run and the wiring. from there it's programming time.

I have been discussing with the fab shop about producing these as units and not one off items, and I believe it is possible with reasonable cost.

I expect to have the FI done within the next three months. again, time restraints. Once this is done, I will begin incorporating the supercharger into the mix.

I would not expect someone who has bought a low milage concourse car in which they will drive periodically and want it to be show stock to want this. But, I am sure there are several of you (including me) that have been drooling over the power increases with the foced air induction systems only to comment about how great ours sound. I want power baby! I also figure that there are some of you who are racing your cars and want this option. you go to the carbs to get away from the limits of the CSI, but you have to deal with the limits of the carbs. EFI is the best of both worlds.

If this goes well, I would look at doing the same for the 2V models. the only issue here is that the intakes are way different and I would have to design from the head up. doable, yes, but not for a hobby. I don't even have a 2V CSI 308 to try it on...

again, let me know what you would consider a resonable price for such a kit. (not including the supercharger)

Thanks,
Dan

 

with Carb's there are two ways to add forced air induction. draw through or push through.

with the push through design (the turbo or SC before the carb) you are limited to the amount of boost you can provide without having to box the whole carb. as the throttle bushings wear, you will end up with leaks etc as the air pressure will simply blow by these points. Carbs meter the air fuel based on the ventury effect. Carbs are also jetted and metered to operate within one atmosphere. when you get into boosting you can see a pressure difference upwards of 1.5 to 2 atmospheres. this gets tricky in tuning the carbs to work within this range and maintain drivability and gas mileage. A boxed carb (meaning, to completely box the carb in so that the complete carb is inside of the compressed area) is ideal but takes up space and makes tuning more difficult as access is limited. Remember, you still have to get the throttle cable etc, to the carbs.

the draw through design (the carbs before the turbo or SC) is what you generally find on production cars (the 4.9L Turbo Trans Ams for example). This allows the carbs to still work within a one atmosphere range, and keeps you from having to box them in, or worry about high pressure leaks. the con is that this is a hard package to get under the hood and still has tuning limitations and compromises. One major compromise is that you now have a wet air system which you are compressing and forcing to make turns which both cause the fuel to "fall out" of the air stream.

when you add in multi-carb engines like the 308, AND the limited space, you end up with a multiplied problem. FI eliminates all of this.

CAN you put forced air on a carb'd 308? I think so, but is it worth the hassle, cost and drivability issues, I think not.

 

a 4.9L turbo Trans am engine
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