[terrible_buddhist]

the point of fuel injection is to get the fuel as close to the combustion chamber as possible...right? I mean, I know there are other reasons...but that is one of the main ones. right?

So in blown set up, why bother running EFI above the blower?

my follow up question is...in a draw thru Turbo set up, can you run a wet nitrous system into the manifold, or will it not be able to inject say 7 pounds pressure of fuel into a 10 pound pressure of boost and cause a lean out?

 

[IMPATIENT 1]

fuel distribution in the boost ain't great with injectors at the runners. its better to swirl em around in the blower so it breaks up well. i hear alot of efi guys having issues because once they get to a certain point , the injector is basically just a open/close valve and squirts in raw unbroken fuel. more or less its not misting as it should. fuel distribution and air fuel ratio, that's what its all bout.

 

[terrible_buddhist]

fuel distribution in the boost ain't great with injectors at the runners. its better to swirl em around in the blower so it breaks up well. i hear alot of efi guys having issues because once they get to a certain point , the injector is basically just a open/close valve and squirts in raw unbroken fuel. more or less its not misting as it should. fuel distribution and air fuel ratio, that's what its all bout.

so, wouldn't it be a hell of a lot cheaper to get a good carb and some dyno time?

I am just trying to get my head wrapped around the point. And if the point is...it really looks cool...I am good with that

 

[IMPATIENT 1]

so, wouldn't it be a hell of a lot cheaper to get a good carb and some dyno time?

I am just trying to get my head wrapped around the point. And if the point is...it really looks cool...I am good with that

why do you think i built a blow thru carb deal?

 

[bajadad]

You can make your draw thur a blow thur (EFI), then put a NOS plate on it. Tuning capabilities are almost endless...especially with a Stand-Alone fuel management system.

 

[s2k1]

You are thinking of EFI as a fuel system. Most "EFI" systems are really engine management systems. They control a lot more than fuel, things like ignition timing, boost control (on a turbo setup), dry NOS, data logging, etc. You could even set it up to measure water pressure in a jet, and log the data. On modern engines, they control things like constantly variable valve timing, drive by wire throttle, etc.
With more control over the ignition, you can really maximize the torque available from the engine by using a timing table that references RPM versus boost, and tune for MBT. Minimum (spark advance for) best torque.
An EFI system won't make more power than a carb, (unless one of them is tuned improperly) but will often make the engine more driveable.

 

[ap67et10]

in most aftermarket engine management systems you have a batch or bank fire setup. if it doesn't have a cam position sensor its not fully sequential. however even with a batch or bank fire you will in all cases have better fuel mileage and control of fuel deliver than any carb (givin someone that knows how to tune). in the really high dollar setups i guarantee you can find some lost power as you would have a cam sensor and crank sensor that will allow fully sequential fuel and spark delivery. so now you just created (in a v8) 8 individual engines that can be completely tuned to maximize its efficiency from that specific cylinder. its is crazy the kinds of things they are doing today with engines. but to say that a carb and efi are equal is rediculous. if we did not have computer contolled engines how would we ever have factory production engines that are getting crazy fuel mileage along with 500-600 hp...untouched?...not to mention in far less cubes then all of us do here.

our new jaguar XFR comes with a supercharged 5.0L...thats right 305 ci. and with 11.6pounds of boost puts down 510 hp and 460lbs tq. oh and it gets 15 mpg in town and 22 on freeway

efi is such a generic term, but just as said above a computer controlled engine has so much more to offer...if you know what you are doing. i have seen computer controlled setups becoming really popular in the last few years in the aftermarket...however there for a little while all i heard was neg feedback, and all of it was because the engine builder, tuner, or customer had no idea what they were doing and caused tons of dollars to be waisted. carbs are pretty simple and very effective, but given the right resources computer controlled is most definately my vote.

AP

 

[s2k1]

in most aftermarket engine management systems you have a batch or bank fire setup. if it doesn't have a cam position sensor its not fully sequential. however even with a batch or bank fire you will in all cases have better fuel mileage and control of fuel deliver than any carb (givin someone that knows how to tune). in the really high dollar setups i guarantee you can find some lost power as you would have a cam sensor and crank sensor that will allow fully sequential fuel and spark delivery. so now you just created (in a v8) 8 individual engines that can be completely tuned to maximize its efficiency from that specific cylinder. its is crazy the kinds of things they are doing today with engines. but to say that a carb and efi are equal is rediculous. if we did not have computer contolled engines how would we ever have factory production engines that are getting crazy fuel mileage along with 500-600 hp...untouched?...not to mention in far less cubes then all of us do here.

our new jaguar XFR comes with a supercharged 5.0L...thats right 305 ci. and with 11.6pounds of boost puts down 510 hp and 460lbs tq. oh and it gets 15 mpg in town and 22 on freeway

efi is such a generic term, but just as said above a computer controlled engine has so much more to offer...if you know what you are doing. i have seen computer controlled setups becoming really popular in the last few years in the aftermarket...however there for a little while all i heard was neg feedback, and all of it was because the engine builder, tuner, or customer had no idea what they were doing and caused tons of dollars to be waisted. carbs are pretty simple and very effective, but given the right resources computer controlled is most definately my vote.

AP

If you are referring to my post, I said power, not driveability, emissions, or anything else. And, I was only referring to peak power.
Trust me, I am an EMS advocate through and through. Just finished wiring up a BITD 7200 race truck with a MoTeC M600 system yesterday.
Also, there are other ways to do sequential than with a cam position sensor.

 

[Outlaw]

another benefit would be tune up, weather changes during the day
how many peeps change their jets during a day at the lake or during a race day for that matter. if you boat at different places or at different temps, a good EFI system will be on tune every time.

how many carb guys can get a perfect tune throughout the entire
rpm range?

strictly power, not much difference
overall power, fuel consumption ,drive ability EFI wins every time.

IMO

 

[ap67et10]

If you are referring to my post, I said power, not driveability, emissions, or anything else. And, I was only referring to peak power.
Trust me, I am an EMS advocate through and through. Just finished wiring up a BITD 7200 race truck with a MoTeC M600 system yesterday.
Also, there are other ways to do sequential than with a cam position sensor.

yes you are correct, sorry for the misquote, in peak power they can be very comparable. but it is my experience that ultimately the biggest number on the dyno sheet is for bragging rights more than functionality, because in reality it is what happens throughout the rpm range that matter most, which is exactly where ems come in very handy.

you are also correct about the cam sensor. there are other ways to do it, but typically in a bbc, bbf or any of these 60-70's era engines a cam sensor is the more effective ways.

another thing i'd like to say (just to clarify...if there was any confusion) is that throttle body injection has only slight benefits from a carb...and those will only be seen in a low power commuter for cold start, emissions, and mpg. to gain any real ground on a carb in a high hp deal you have to go to mpi.

i am a big advocate for ems because of the great results i have had, carbs work great, and i will have pletty more carb deals in the future, but there is definately something to be said for ems, especially when setup by somebody that knows something...which tends to be few and far between.

AP

 

[terrible_buddhist]

Don't get me wrong...I like EFI as well...I did it on my truck and had some great gains especially in drivability. My main question was MPI on a blower when after the blower there is no MP to I it in...its just getting sucked or forced in like a carb

How about the NOS question on the manifold for a draw through?

 

[IMPATIENT 1]

Don't get me wrong...I like EFI as well...I did it on my truck and had some great gains especially in drivability. My main question was MPI on a blower when after the blower there is no MP to I it in...its just getting sucked or forced in like a carb

How about the NOS question on the manifold for a draw through?

hass runs nitrous on a draw thru right now. plate ontop of the intake with fuel pressure regulated 1 to 1 with boost, ya gotta increase the pressure at the plate to overcome the boost.

 

[terrible_buddhist]

hass runs nitrous on a draw thru right now. plate ontop of the intake with fuel pressure regulated 1 to 1 with boost, ya gotta increase the pressure at the plate to overcome the boost.

interesting.

I figure doing a plate under the carb = no problem...but some interesting stuff needs to happen to do it at the manifold

 

[IMPATIENT 1]

interesting.

I figure doing a plate under the carb = no problem...but some interesting stuff needs to happen to do it at the manifold

we're just gonna give my uncle's plate methanol only, no nitrous, and just have it turn on at 15lbs of boost at 45-50psi of pressure all the time

 

[terrible_buddhist]

we're just gonna give my uncle's plate methanol only, no nitrous, and just have it turn on at 15lbs of boost at 45-50psi of pressure all the time

That sounds pretty interesting...how are you hooking that up?

 

[ap67et10]

Don't get me wrong...I like EFI as well...I did it on my truck and had some great gains especially in drivability. My main question was MPI on a blower when after the blower there is no MP to I it in...its just getting sucked or forced in like a carb

How about the NOS question on the manifold for a draw through?

with most mpi engines the fuel pressure runs up around 45-65psi which is still plenty more than most any boosted engine. i don't know nearly enough about what these big guys are running, but it sure seems that most guys running 1500+ hp on boost (especially centrifugal blowers) tend to run efi. there are plenty still going carb, but there must be a reason so many are quickly changing over to efi in huge hp deals. I know mine will be efi on a procharged bbc. to each his own i guess, but clearly it works and is penty programmable even under boost.

if it wasn't effective and as efficient, then manufacutres whouldn't still be doing it on all the production s/c vehicles. its clearly more efficient and completely controlable (emissions) even under boost.

and once again i think the main thing is that this debate really only pertains to anything that is NOT wot, because ultimately efi or carb, you are just dumping fuel in, typically there is no o2 readings or closed loop operation under wot, and in both cases a dyno day would be used to either program the ems at wot or setup the carb for wot. the primary advantages are the endless touch of a key adjustments, and part throttle and idle effiency and tunability.

not too sure about the draw through and nitrous, but it would seem to be just as effective in either setup, but i think it would have to be a wet system in both cases. like i said...not too sure on that.

AP

 

[ap67et10]

like IMPATIENT 1 said, it does seem that most boosted guys either run methanol or alcohol injection or they may run nitrous directly on the surface of the intercooler for intercooler cooling. most don't tend to run nitrous into the engine, however they are out there....typically with the roots stuff

AP

 

[Skeeter Fogger]

So in blown set up, why bother running EFI above the blower?

The people at Sterling Engines answered the very same question when I asked it. It's because with out running the blower wet, they ran into problems with the seals frying almost instantly.

I believe they run injectors in both the port and on top of the blower now.

 

[Hass828]

hass runs nitrous on a draw thru right now. plate ontop of the intake with fuel pressure regulated 1 to 1 with boost, ya gotta increase the pressure at the plate to overcome the boost.

When I raised it 1 to 1 it went pig fat! Believe it or not the , the way the nos plates from NOS are set up the nos blows right across the holes in the fuel bar and draws the fuel out even in a boosted enviroment. I wound up right back at 5 1/2 psi flowing.
Scarry the first time or two that you do it because common logic says that it wouldnt get "any" fuel with 5 1/2 on the plate and 17psi in the manifold . I started out 1 to 1 and slowly backed it back down till I arrived at this conclusion. Been running it this way for years with no problems.

 

[Hass828]

my follow up question is...in a draw thru Turbo set up, can you run a wet nitrous system into the manifold, or will it not be able to inject say 7 pounds pressure of fuel into a 10 pound pressure of boost and cause a lean out?

If you are going to do this, you better have a stout bottom end and a good driveline cause it turns that little draw through turbo deal into a hammer


Oh yea, and an MSD 7AL3 wont light it off on the nos, needs to be a mag, good luck, Hass