EFI or carb for turbo ford200??


Well-known member
I posted this over at the drawthru turbo group and i wanted to get your opinions too.

on the one hand i agree that the 32/36( progressive, 320cfm) vs the holley2300 (500cfm). If i go progressive, you can easily attain off boost low rpm manners and economy, and up top whilst it's not huge in total airflow, it would probably still flow more than the inlet arrangement would allow.

I have another question though. i went to a local turbo shop here in
denver. and the owner recommended that i use an SDS fuel injection
system. he brings a valid points about a carb only having 4 or 5
circuits to control air/fuel mixture. whereas EFI can do it all thru
the whole rpm range. i have read some other posts and done other
research(mchinnes and corky bell) i get the feeling that with a carb,
i will be running lean at WOT and that could be a problem.

with this true i WOULD want EFI. however there is a $900-1300.00 cost.

here is the decision point: will i be ok with just a carb?? if i
have a carb custom built for my application. will i spend more or
less than an EFI? will a custom carb have as much performance as

i didnt get the feel that he was trying to sell me a efi system. but
i do think that his job(of satisfying his customers - Me) is made
easier if i go to the EFI

this is going on a ford 200 cu inch(3.3L), fuel log head, 1.75I, 1.5E
t3/t4 turbo, intercooler, 5500rpm, denver, 10psi boost,

Ben and Dan i especially wnat to know what you think. i knwo there are some out there running efi on the log head and i wanted to know waht you think!!

"we all stand ont he shoulders of the men who came before us!!"

previous replies>
> Due to the nature of your inlet arrangement - I doubt that more than
> 350cfm (even then I wouldn't make bets on it) would be able to pass
> through the inlet as it is - so there's no point going any bigger with
> the carb - the inlet manifold is a bottleneck - and the weak link that
> would need to be addressed before any extra flow could even be used.
> > With that in mind, although it's something more likely optimal for
a sub 2 litre engine, perhaps a weber 32/36 dgv would be a good option.
I don't have a turbo, but I do have the SDS on my crossflow and I have to agree that it's the easiest thing to setup for fuel and ignition curves.

At every 250 rpm breakpoint I can set a fuel value. I can also adjust it for load via the MAP sensor. Unlike a carb, I don't really ahe to compromise on a single jet to take it thru a range of rpm or load.

Same with ignition. I can set ignition values to correspond to load and speed so that I get exactly the advance curve I need. With digital mapping you can do some things that are impossible with mecanical and vacuum systems, like knock sensing. Because of that ability to very finely tune the engine in numerous conditions you can go to higher boost levels.

The other big advantage is feedback. You can fire the car up and watch the computer and engine interacting on the keypad thru the built in functions. Vacuum, ignition, fuel, rpm are all there to see. You can easily add an EGO meter to watch mixture at the exaust. You can make changes on the fly to adjust the engine to optimal performance. No jets, valves, rods, springs, or diaphragms to deal with.

Turbos can be made to run just fine with a carb. I just think that you have some inherent compromises with a carb that you don't get with EFI.

You can go with a carb and it would be cheaper but EFI would probably be very easy to setup. I am also worrieda bout trying to tune a turbo carb at your altitude. It seems to me the altitude should not be a difference.

In the book "Turbocharging" by Hugh MacInnes he gives some diagrams and a explanation of how to generally modify a carb for use with a blow through turbo setup.

In short you run a little bit richer on the primaries and use the secondaries to provide the fuel enrichment.

The part I got confused on was that you need to route boost pressure through the vacuum source so that the secondaries open with boost pressure instead of a vacuum signal. Also you need to run a boost pressure referenced fuel pressure regulator so that fuel pressure goes up with boost pressure. IIRC the idea is if your carb requires 7 lbs fuel pressure for a Holley 2300 series carb and boost is at 10lbs you need 17lbs fuel pressure.

Also according to info I have been able to find all carbs sold in the USA after 1977 are internally venting. This mean you dont have to worry about the carb building up too much pressure in one are or the other. It is equalized through internal venting.

Im not quite sure where to run the referenced boost signal to to get that result. The diagram in the turbo book showed an internal circuit to hook into.

Also on a blow through carb turbo you need to use nitrophyl floats otherwise the boost pressure can crush the floats.

With the EFI you hook it up and then set the fuel values like Mustang Six said. The EFI should already have a good fuel pressure and IIRC you just need a sensor to show boost pressure so the EFI computer knows when to add more fuel.

If you can find someone who knows how to do it and set the carb up the carb will be cheaper and easy to set up. Problem is finding that knowledgeable person.

If I go turbo on mine I will be running a carb but Im still researching the ins and outs of the setup.
Pete, if you have the money go with EFI. EFI offers higher HP readings and most likely better fuel economy.

If you go the Carb route, dont worry about running lean at WOT. You can set up an extra fuel injector somewhere that is activated by a boost sensative switch. Ive seen it some where on a twin turbo pinto or something.
Good stuff. The man's got it together. Real world experience, honesty, and takes the time to share.

;) He'll be advising you fit a Holden stroker next...
ok i just came from barnes and noble. i waa looking for the holley fine tuning books.

it said there are a couple of carbs we should know about especially for turbo applications

the 2300 is a synchronous 2bbl 350 and 500 cfm carb

the 2305 is a progressive 2bbl 350 and 500 cfm carb

the 2010 is a synchronous 2bbl in the 350 and 500 carb(designed and made in 1992 for oval track). i think it said that you could get 30cc and 50cc power nozzles for these.

all are the front half of the 4300/4305/4010 4 bbl version

man i get goosebumps just thinking about a turbo installation on my 200!!
How come nobodies talkin about superchargin a 200(the centrifrugal type not the roots)? NO LAG!!!!
I guess the horsepower it kills is the issue but I still think it is a good prospect...

I'd do but I'm only 16 and lack the funds

but thats the plan

PS what figures would a supercharged 6 produce?
A properly sized street turbo has little to no more throttle lag than the same engine with a centrifugal, a Roots blown engine has less lag than either. Lag occurs when turbos are either oversized for the application or intentionally sized to deliver maximum boost like for circle track or LSR cars. How much HP you can gain with a blower depends on how you build the engine and how much boost you are running. Super or turbocharged engines typically make something between 130% and 300% of the power output of their normally aspirated equivalents. It all depends on how much you want to spend and how often you want to put it back together.
a 200 is kinda tough to SC since there are no easy ways to mount the SC and have a short belt. a turbo is much more efficent at about 75-80%


Also in the turbo charging arena. Turbo lag shouldnt be much of a problem oin our cars. Look how long the turbo path is. From turbo, through engine back to turbo isnt but about 20". Some intake tubes are longer than that. This is one part where having both ports on same side makes turboing fairly easy. Now if we could just get a port injection system it would be easy.
Has anybody tried to mount MPI to the log on a 170-250? I mean actually drilled holes in the log and mounted one up?
Some guys up in the Newcastle area were playing with EFI on a 2V manifold. Not sure about the log head. I think the main consideration is how the injector bosses could be securely attached. Problem also is that the spray would not hit the valve stem/underside of head like a crossflow, so some of the effects are diminished.

I have heard of people modifying the Crossflow EFI intermediate manifold to fit injectors - but again on a 2V. This is getting into serious fabbing/experimentation territory...

Regards, Adam.
I started drilling into a log to mount bungs, but after thinking about it, it dawned on me that port EFI would give great fuel distirbution, but would not help with airflow. The log is not really big enough to do the job and you'd still have to slice it up somehow to add a big throttle body. The payoff wouldn't be worth the effort, in my estimation.

Then I started looking at the Tempo CFI, but wasn't sure I could get enough air or fuel out of it to go much past 150 hp. I think you ended up with a part of that project.
I am sroucing a CFI setup right now off a 3.8L to put on a E0 head. mill it flat and bore hols for the TB. I think this will be the easiest/best bang for the buck efi you can throw on the US six. not sure where it is going from there but I am at least getting the project that far.

Thanks, Addo, but as you surmise, I was thinking specifically of the log-headed US engines. :D

Jack, you are right, the Tempo CFI faces severe performance restrictions. Furthermore, my investigations convinced me that it can't be adapted to the I-6 engines anyway, since the ECU is counting the dizzy pulses and controlling the injector as if the engine had only 4 holes and a much smaller displacement. I think our Favorite Squiddy fist pointed this out... ;) So I think that Nick is on the right track - the CFI off the late 80's bent-6 stands the best chance of success, IMO.

OTOH, the later logs flowed a lot more air than the earlier ones. Perhaps not enough to threaten a stout 5-liter, but certainly enough to support a more spirited drive. And don't underestimate the benefits of better fuel distribution, either. We've all seen how the current system leans out the front and rear holes, leaving the center cylinders too rich. MPI could completely eliminate this effect, giving us not only better power, but a longer lasting engine as well.

Anyway, I was just wondering if anyone had actually tried it, and if so, how it had gone.

Happy Holidays! Stan