Why convert EFI to Carbs!?

[SkiFree]

Because Nascar.

Nope --- http://www.autoblog.com/2011/02/11/n...-supply-contr/

[u3b3rg33k]

Carbs will make more peak power at WOT than a FI setup, And you can get away with way more than 850 cfm in a "850 cfm" carb. They're all generic so to speak. You're not winning if you're not cheating on the racetrack. Oh and their easy to jet up or down for weather conditions to correct the horsepower vs a FI setup. Get your self a flow bench and dyno and you will see.

They both have pros and cons, the FI setup will be more street friendly and have less maintenance for a daily driver or street car. And before anyone calls BS, I have credits in courses of specific training, have talking to the old goats who know their shit in nascar, as well as had many hours on the flow benches with heads with carbs, etc.

Since when is that true? F1 must be missing out bigtime on power.

Because Nascar.

Nope --- http://www.autoblog.com/2011/02/11/n...-supply-contr/

Fuel efficiency ought to go up, as will horsepower.

Carbs will generally have much better throttle response then a single throttle body style EFI setup. But if you go individual throttle bodies, it becomes null.

My 2002 has a mechanical secondary. If you go WOT at too low of an engine speed, it doesn't do much. if you open the throttle at just the wrong pace, the accelerator pump doesn't have enough pressure to spray out the fuel properly, and it dribbles down the side, causing a brief power hole. Put your foot down fast enough (or slowly enough), and it does what you want. EFI doesn't have that problem. also, if you open the secondary at too low an RPM, there isn't enough velocity for both, and it bogs. again, EFI win.

I'm going to call BS on some of that. Perhaps if you have an aftermarket, tuneable EFI system, where you can tweak things, but OEM off the shelf, not a chance. I know for a fact that I can't tune EFI. I also know that I can set up a set of carbs pretty well (as long as they aren't some 4 barrel for a V8, I don't have the slightest clue how to work on those.) I will say that my 43 year old Datsun will start faster cold than my M3 any day of the week, and that's with no choke hooked up. Heck, hot it will out start the M3 as well. Is a wide band o2 sensor a useful too to set carbs up? Yes, you bet. It saves lots of time.


More modern EFI setups are likely better than Bosch D-Jet or things like that, but they still are a preset item. Unless you happen to have something like Megasquirt or the Miller WAR chip, odds are that your car isn't totally right. Every car is different and any broad based chip isn't going to be 100% right. I've read that quite a few of the chips out there for the S14 are a death sentence for it if you happen to be in California where 91 octane fuel is the best you can widely get. The aftermarket chips are designed for 93 or higher and have too much spark advance causing them to ping and have other problems. Eventually the motor is a boat anchor. Granted, you can very easily do this with carbs, but its a simple jet change to fix as well.

My M20 starts the first try, every try, and the colder it gets, the better it starts. if it's 20F or colder out, it starts on the first pulse (or whatever you call M20 starter noises). I don't see how there's room for improvement there (cold start enrichment FTW! emissions be damned!). Now that i've had my injectors cleaned and replaced the one that leaks down, it doesn't care what the temps are - it seems to just do what I want, namely start and run.

I grew up on carbed cars. I remember starting stuff with thermo-chokes, carbs with single wire O2 adjustment (why god, why?), and ceramic heater equipped VW carbs, and other "features". I also remember all the tweaking we had to do to them to get them to do what they were supposed to do but didn't (like start in the cold). Don't tell me all that add on nonsense beats EFI.

If you want real proof that EFI is better, pull a bike out of the garage, fire it up, and go WOT in gear at 1500RPM cold. Even a well tuned carb will have trouble with that. Hell, my KZ1000 doesn't like doing WOT below 4000rpm with its ITBs. Not enough velocity to make it work. maybe with those fancy velocity compensating carbs they have on newer stuff, but a maf or map setup just works better.

Anyone running a souped up S14 on 91 octane doesn't deserve an S14. If you're running a chip on cheap gas, you deserve what you get. Keep the spare OEM ecu around for that kind of stuff or suffer the consequences.

As for the miller MAF & WAR chip, I love mine. I was chasing down quirks for ages, ditched the AFM, and BAM, problem solved. Peak torque is back, throttle response is amazing, it sounds better, and there's probably other measurable benefits I don't care enough about to measure (like fuel economy and emissions).

[SkiFree]

My 2002 has a mechanical secondary. If you go WOT at too low of an engine speed, it doesn't do much. if you open the throttle at just the wrong pace, the accelerator pump doesn't have enough pressure to spray out the fuel properly, and it dribbles down the side, causing a brief power hole. Put your foot down fast enough (or slowly enough), and it does what you want. EFI doesn't have that problem. also, if you open the secondary at too low an RPM, there isn't enough velocity for both, and it bogs. again, EFI win.

A properly tuned/functioning carb won't have that issue either. What you're describing sounds like the diaphragm on the accelerator pump is due for replacement.

Obviously triple carbs on an M20 is going to give you a quicker throttle response when compared to a single throttle body. Not sure how your reasoning refutes that?

[Tree18is]

just because its old doesnt mean it sucks

Its a preference thing, Someone who knows there carbs *not many* can make some serious power just like someone who knows their Fuel injection. Plus it gives a unique sound and throttle response when done up all right.

[Jhonno]

Carbs vs. Like for like EFI (Individual TB's) EFI wins everywhere, excepting maybe noise, ish, which is a subjective.

[SkiFree]

Carbs vs. Like for like EFI (Individual TB's) EFI wins everywhere, excepting maybe noise, ish, which is a subjective.

[Jhonno]

and yet the debate continues..

[SkiFree]

^ True... like Tree above said.. it's a preference thing.

[u3b3rg33k]

Obviously triple carbs on an M20 is going to give you a quicker throttle response when compared to a single throttle body. Not sure how your reasoning refutes that?

Port injection gets the fuel closer to the valve than carbs do. If you have a MAF, all you're waiting for is the column of air to start moving. the AFM itself adds monstrous delay in comparison (most notable when going from closed to WOT).

Carbs vs. Like for like EFI (Individual TB's) EFI wins everywhere, excepting maybe noise, ish, which is a subjective.

[xwill112x]

Since when is that true? F1 must be missing out bigtime on power.

Since i've helped dyno tune several DEI cars to make over 850 horsepower. Let me know when you do this with 358 CUI N/A. I've done the flow benching, I've set the carbs up, i've flow benched the heads with the carb vs throttlebody. Let me know when you replace your cam and lifters with electronicly controlled soleniods then bring up f1. Do the dyno time, and real world work on the actual cars and come back talk. Theres a reason nascar ditched the fuel injected idea. yea they go around in circles like fags on a track, but the engine building and R&D is top notch, which I have participated in.

[LJ851]

Its a preference thing, Someone who knows there carbs *not many* can make some serious power just like someone who knows their Fuel injection. Plus it gives a unique sound and throttle response when done up all right.

Fuel injection will always win.

Especially comparing the single throat per cylinder setups (apples to apples). A perfect example of this are PMO carbs for 911 Porsches. They are basically a a triple throat weber IDA with all the bugs/ compromises worked out of it. It is widely considered the the finest carb to put on a 911 engine. They are functional works of art.

A few years ago Richard (PMO) made a throttle body version of his carb. Its the same as the carb except it has injector bungs and no float bowls (basically).

Guess which one makes more and broader power? The ITB's !

I would love to have either setup, but if you put a paid for pair of both kits in front of me, i would probably be leaving with a set of carbs in my hands and a skip in my step.

[nando]

there's no possible way you can make more HP just because it has a carb. Only if you don't know how to tune the EFI system. It's only a fuel metering device. if you made more power with a carb, then your EFI throttle body was simply too small.

There is one benefit to carbs, and that's throttle response. Because of the way the carb works, it automatically does the "accel enrichment" for you. With an EFI system, it has to essentially "guess" how much to enrich on throttle tip in. However on a modern EFI system this really isn't a factor, there's enough computing power to build a pretty close model of the engine that allows accurate AE.

Besides, people get really focused on fueling when thinking about power. Who cares? as long as you can reach your targeted AFR, the fuel metering device doesn't make any difference in power. Even a small change in AFR makes only a small difference in power.

The big benefit to EFI is electronic spark control. . Usually carb's run a distributor, which sucks for a # of reasons. I won't get into all the details, but there's no way in hell a distributor system is as good as an electronically controled coil and 3D timing maps. You could of course run a carb with an electronic spark control. There's just no point - if you can reach your intended AFR curve with a carb, you can do it with EFI. You can then also use that EFI system to match your AFR target at every other load site. you can't do that with a Carb, no way. The problems with carbs is they are basically linear in operation. Optimum engine VE and timing maps aren't neccesarily (and are usually not) linear.

Lets see a carb with this amount of control:



That's just 2 of like 25+ different maps and curves that control everything from spark, fuel, startup and idle, cam positon, injector timing, individual coil and injector trim, EGT corrections, etc etc etc. and this isn't even a "high end" EFI system. a carb basically lets you linearly fuel the engine at WOT. big fucking deal..

[xwill112x]

Fuel injection will always win.

Especially comparing the single throat per cylinder setups (apples to apples). A perfect example of this are PMO carbs for 911 Porsches. They are basically a a triple throat weber IDA with all the bugs/ compromises worked out of it. It is widely considered the the finest carb to put on a 911 engine. They are functional works of art.

A few years ago Richard (PMO) made a throttle body version of his carb. Its the same as the carb except it has injector bungs and no float bowls (basically).

Guess which one makes more and broader power? The ITB's !

I would love to have either setup, but if you put a paid for pair of both kits in front of me, i would probably be leaving with a set of carbs in my hands and a skip in my step.

Correct it will make more broader power, but in a racecar, you're at WOT high rpm's anyway. The carbs will make more peak Horsepower, and Lets see someone change out there injectors in a couple mins to correct their horsepower for different weather conditions. I am a FI guy myself, but to say FI will always win isn't something I will agree with.

And that doesnt seem correct, ITB's are best when tuned to a narrow specific powerband, The make the trumppets at different lengths to try and smooth this out.

The benifit is PEAK POWER and ease of tunablity. Theres a reason most drag cars aren't fuel injected either. Lots of ignorance in this thread.

Until people have seen or put a racecar making 800+ horsepower on the dyno and tuned to make 850+ within 15mins, with their hands, stop posting things you've read on wikipedia.

[nando]

Correct it will make more broader power, but in a racecar, you're at WOT high rpm's anyway. The carbs will make more peak Horsepower, and Lets see someone change out there injectors in a couple mins to correct their horsepower for different weather conditions. I am a FI guy myself, but to say FI will always win isn't something I will agree with.

The benifit is PEAK POWER and ease of tunablity. Theres a reason most drag cars aren't fuel injected either. Lots of ignorance in this thread.

HOW can the carb make more PEAK POWER? All it is doing is sending the fuel to the engine, and not even in a good way - why do you think EFI uses port injection and not throttle body injection?

how is it easier to tune that plugging in a fucking laptop and letting the computer do the work? taking apart the carb to rebuild it, setting jets and floats and mechanical bullshit? I can tune my entire WOT range with 3 full throttle pulls (MAYBE 15 minutes, and I don't even need a dyno). How long does it take you to do that with a carb? how many hours? I'd rather spend that time on my spark curves. Ambient conditions changed? oh fuck, there goes your tune..

please god, I want to bitch slap you so bad...

[xwill112x]

HOW can the carb make more PEAK POWER? All it is doing is sending the fuel to the engine, and not even in a good way - why do you think EFI uses port injection and not throttle body injection?

how is it easier to tune that plugging in a fucking laptop and letting the computer do the work? taking apart the carb to rebuild it, setting jets and floats and mechanical bullshit? I can tune my entire WOT range with 3 full throttle pulls (MAYBE 15 minutes, and I don't even need a dyno). How long does it take you to do that with a carb? how many hours? I'd rather spend that time on my spark curves. Ambient conditions changed? oh fuck, there goes your tune..

please god, I want to bitch slap you so bad...

I've told you how long it took me to do all that 15mins, and your fuel maps and spark maps aren't making 850 horsepower are they? You dont need a dyno, because you dont have a real racecar making 850+ rwhp. 1 full throttle pull , jet up, another pull see if it responds well, etc. It makes more power thru FLOWING MORE AIR / FUEL at PEAK RPM's within they class of 850 cfm because they are not all "850 cfm" per say. A flowbench will tell you that. gah mods can't stand to be wrong can they.

If fuel injection ALWAYS WINS, I want to see a FI setup making 5000+ horsepwer and drink the rate of fuel as the top fuel dragsters do. Please show me so I can enlighten the rest of the racing world.

And again, I'm a FI guy, but not for a racecar. Simple as that. Theres a reason all the big boys in Drag racing and Nascar use CARBS. Funny huh?