Since Scott was trying to bring a few additional people into his EFI -vs- carb debate on the Ford forum I thought I would post this here since I know not everyone here reads either the ford forum and general car chat.


He wants a debate so I figured there are quite a few PA people who can add to the subject.

 

I guess the option of debate does not include any information that Scott disagrees with so he locked the thread, unfortunately in the middle of my post pointing out the errors in his last 'rebuttal' to my own.

PCVR? I guess if you used four words instead of an odd ball acronym I might actually know what the hell you are talking about.

If you don't know anything about metering rods then I would suggest you do a little internet research on the subject. I don't know where you get the idea that they are some kind of third world technology. They were used in everything from GM's rodchester quadrajet to nearly every CV carb in existance. For each paragraph of practical knowledge I post here I get arrogant ignorace from you in return.

I can honestly say I have worked on nearly every type of carb and since carbs are still used on aircraft to this day they actually bothered to teach us a bit about EFI, MFI AND carbs to make us aerospace engineers know something about how all those funky tubes, valves and orifices work. I am pretty sure your carb does not defy the laws of physics when it comes to mixing fuel and air.

And another FYI for you, if you think that some WOT on the dyno or some revs in neutral is going to reveal all of your carbs tendencies then you are fooling yourself. Its no wonder people from the shop where you work is getting done are razzing you about your project.

What you need to REALLY worry about is when you are cruising down the road at parial boost, full temp, and with hot fuel and you go from 20% throttle to 50% throttle. Thats when you will discover why carbs and turbos are not a good combination for a car that will be driven on the street.

But as I have already stated, that is your problem, not mine. You have already said that the new carb was dead on right out of the box but that you had other issues and now you are telling me that you have already changed out the jets. Pick a story and stick to it man.

And you can make fun of my mechanically fuel injected 80s turbo technology all you want, but it maintains a perfect a/f ratio right up to 300 RWHP under all conditions and I now have a nice piggyback EFI solution to squirt in another 200 HP worth of fuel on top of that. When I tune my car, it will be from the comfort of my drivers seat.

If you only end up pushing in the low 500s I won't be far behind you despite being water free and only packing 3.3 liters of displacement. Thats not a bad package for a car that weighs almost a thousand pounds less than yours.

If you really want to put your money where your mouth is perhaps we should have a friendly wager about who's system will product more HP/Liter at 14 psi of boost when our projects are complete? With a bet like that you don't even need to worry about how streetable your system is.

If you don't dare we will eventually see how we each do at the track anyways.

Well, that was all I was going to say so now that scott doesn't want to hear any more information that he disagrees with I will leave it at that.

 

scotts setup is very nice, i must admit, and it seems to be running just fine. any other time, i would by no means try to turbo a carbed car.

 

Damn, I almost forgot this thread was here but I guess Scott occasionally reads the turbo forum.

I would love to see an updated graph showing us how well scott has cleaned up that a/f and power curve.

 

this may sound dumb but alot of this stuff I am still learning.

carb engine gets its a/f from a jet in the carb itself, that adjustment is based on the amount of air flowed by the carb. i.e. if the carb flows more air ( say from increasing boost ) then a bigger jet is needed to keep the a/f the same, correct?

efi gets the a/f from the air sensor and the ecu tells the injector ( the efi equivilent to a carb jet) what they need to do, in effect changing the jet setting constantly to compensate for atmospheric changes, like altitude and temp.

If this is correct and I understand it right then the carb turbo would have to be at a fixed boost level the entire time your on the road in order to keep the a/f where it should be.

that leads me to believe that while the carb is tuned perfect today then tomorrow it could be off, and there is no way on a carb system to run low boost ( to keep fuel economy good, well as good as you can get from a carb) on a daily driver and then turn up the boost when the guy next to you wants to show off.

wait it would be possible to increase boost on the fly in a carb but wouldn't that mean you need your passenger to crawl under the hood to tinker with the carb.

in a point and shoot car I can't say that fuel economy is important and you keep the boost set, but in a daily driver carb is just throwing good money down the barrels.

 

go research blow-through carbs, FMU's. your knowledge of carbs was similar to mine, as i barely knew anything about them.