EFI benefits with Carb appearance?

[68rustang]

I saw that "carb style" throttle body and thought, "that would be cool for my setup too. Then I realized that it probably won't work for me because there would be no where to put the MAF.

Check out: http://www.mass-floefi.com/ they use a modified GM MAF sensor that sits between the air cleaner and the 4 barrel throttle body.

 

[ForceFed70]

Yes, the MAF does create another restriction in your intake, but do you really think that wire generates enough heat to make an appreciable difference in intake temps? I have to disagree there.

AW

Thanks for your insight.

I think it's more of a restriction because of the size of the MAF and not the actual wire. For a MAF to be accurate, you want the air moving across it quickly. Which means using a small port diameter. The tradeoff for accuracy is a small restriction to airflow. Not too bad when in stock trim but when you start modifying your engine, it can become a major bottleneck quite quickly. Generally one of the 1st performance modifications done to a mass air engine is to upgrade to a larger MAF. A non-issue with speed density.

You may be right about the heat not making a big difference. I've never played with it enough to see exactly how much heat is generated. I have been told that the wire is heated to over 300* tho.

 

[ADub64]

To clarify, we have brought up 2 different EFI setups. The throttle body injection (see the holley link above) and multi port inject. multi port (see the mass flo link) can run speed density or MAF. Throttle body injection (TBI) only runs speed density. Multi port injection (MPI) has a throttle body, but its really only an air valve. TBI has the injectors (2 or 4 injectors) sitting above the throttle blade and shoots fuel/air through the throttle body. MPI has 1 injector per cylinder which shoots fuel into the air stream just before it enters the cylinder head. MPI is much more accurate and for anyone with performance in mind, MPI has more to offer than TBI. If all you are concerned with is keeping it looking like a 69 mustang engine, why spend the money on TBI, it really gains you nothing. If you want to work on performance and play with EFI, MPI is the way to go. Then you still have to choose speed density or MAF. As far as keeping the look goes, speed density makes that easier. I believe mass-flo are the only guys offering the MAF setup in a carb style package as opposed to an induction system similar to the 5.0 HO engines. Any of the EFI retrofit packages will need tuning out of the box to work properly, there are just too many engine differences for a generic tune to be optimal. So to do it right, plan on doing some tuning.

 

[jikelly]

It's pricey but a better overall system than the ones already mentioned which are speed density systems.

http://www.mass-floefi.com/

It is a mass air system just like the 89 and up 5.0s

It looks pretty, but whoowee it's 3000 bucks!

 

[ForceFed70]

To clarify, we have brought up 2 different EFI setups. The throttle body injection (see the holley link above) and multi port inject. multi port (see the mass flo link) can run speed density or MAF. Throttle body injection (TBI) only runs speed density. Multi port injection (MPI) has a throttle body, but its really only an air valve. TBI has the injectors (2 or 4 injectors) sitting above the throttle blade and shoots fuel/air through the throttle body. MPI has 1 injector per cylinder which shoots fuel into the air stream just before it enters the cylinder head. MPI is much more accurate and for anyone with performance in mind, MPI has more to offer than TBI. If all you are concerned with is keeping it looking like a 69 mustang engine, why spend the money on TBI, it really gains you nothing. If you want to work on performance and play with EFI, MPI is the way to go. Then you still have to choose speed density or MAF. As far as keeping the look goes, speed density makes that easier. I believe mass-flo are the only guys offering the MAF setup in a carb style package as opposed to an induction system similar to the 5.0 HO engines. Any of the EFI retrofit packages will need tuning out of the box to work properly, there are just too many engine differences for a generic tune to be optimal. So to do it right, plan on doing some tuning.

You can run either system with either multiport or throttle body injection...just depens on your ECU.

Why do you say that TBI gives you nothing? TBI is a huge improvement over carb and darn near as good as multiport.

 

[ForceFed70]

Hey, this is a little off topic, but I think you guys are off topic anyway so what the hay.

I saw that "carb style" throttle body and thought, "that would be cool for my setup too. Then I realized that it probably won't work for me because there would be no where to put the MAF. I really don't want to get into an MAF/SD argument.

For right now I'm using the MAF, but anyway...Lets say you had my setup (see sig) w/SD and instead of the Trick Flow intake you used one of those "carb looking" throttle bodies and a spider intake like someone metioned, is there any way to tell which intake would work better without trying it?

Sorry, so what's the question? Which Multiport EFI intake would work better?

I guess that would really depend on exactly which intakes you are comparing. I think you'd have to get flow numbers for an idea. Thinks like port velocity also come into play.

 

[ADub64]

From a driveability standpoint, TBI is better than carb. If you want to build a strong engine, TBI really doesn't offer much more than a carb and can even be a limitation. I built an TBI engine that should have easily made 350hp, but the tuneability of the GM computer and the nature of the injector system just didn't work that well. No way I made the 350 HP, pulled it off and threw on a carb, made a world of difference. I know the Holley system is based off of GM's architecture, but it may not have as many issues. I could easily be off here, but not once have I seen a TBI engine in a high performance car, be it in a show, on tv, or in a magazine.

 

[ForceFed70]

From a driveability standpoint, TBI is better than carb. If you want to build a strong engine, TBI really doesn't offer much more than a carb and can even be a limitation. I built an TBI engine that should have easily made 350hp, but the tuneability of the GM computer and the nature of the injector system just didn't work that well. No way I made the 350 HP, pulled it off and threw on a carb, made a world of difference. I know the Holley system is based off of GM's architecture, but it may not have as many issues. I could easily be off here, but not once have I seen a TBI engine in a high performance car, be it in a show, on tv, or in a magazine.

Hold on.. TBI doesn't mean GM.

TBI can be done with all sorts of different hardware and ECU's.
I agree, GM TBI sucks and the ECU is not very programmable.

Holley does have some systems that use the GM style TBI. But they also have 4bbl (GM stuff is all 2bbl) TBI's that are good for up to 500HP. The holley ECU's come in all sorts of flavors...

And aftermarket ECU's can use all sorts of different Throttle bodies.

A factory GM TBI system is not a good choice for a conversion. But again, TBI is not just a GM thing. Using a programmable ECU and a TBI from a big block chevy should perform very well. The small block GM TBI's are only good to 260HP or so..and the ECU is not programmable. They flow a grand total of 470cfm. The performance problems you came across are strictly due to poor hardware choice for the application. Not because of a design flaw.

TBI systems can be very flexible and make as much horsepower as a MPI setup.

 

[Bullitt]

For right now I'm using the MAF, but anyway...Lets say you had my setup (see sig) w/SD and instead of the Trick Flow intake you used one of those "carb looking" throttle bodies and a spider intake like someone metioned, is there any way to tell which intake would work better without trying it?

if you know runner length, flow efficiencies and so forth you can model both intakes in a desktop dyno program and see what you get.

my bet is you're going to get better torque with the trickflow intake and more HP with the spyder/accel pro-ram/victor jr style intake. the mentioned intakes will also move your powerband higher.

 

[rhyno9]

Hold on.. TBI doesn't mean GM.

TBI can be done with all sorts of different hardware and ECU's.
I agree, GM TBI sucks and the ECU is not very programmable.


And aftermarket ECU's can use all sorts of different Throttle bodies.

The problem with the Mass air is better or Speed density is better in this thread stems from certain assumptions that people are making. So in summary


FACTORY Speed density = Bad
AFTERMARKET Speed density = Good
FACTORY Mass Air = Good (limited on the upper end of performance without tuning)

If you compare factory Speed Density to Mass Air then it's really no comparison. Mass Air is superior.

When you start to talk aftermarket (lots of modifications) then the mass air system starts to lose some luster unless you reprogram the ECU. So then the argument that Mass air is better because it is adaptable to engine modification is no longer valid.

If you spend some time and look at guys running power adders many just junk the stock eec IV for Fast,AEM,SDS,Big Stuff the list goes on and on.

The key to the argument is context.

 

[cougar_68]

The problem with the Mass air is better or Speed density is better in this thread stems from certain assumptions that people are making. So in summary


FACTORY Speed density = Bad
AFTERMARKET Speed density = Good
FACTORY Mass Air = Good (limited on the upper end of performance without tuning)

If you compare factory Speed Density to Mass Air then it's really no comparison. Mass Air is superior.

When you start to talk aftermarket (lots of modifications) then the mass air system starts to lose some luster unless you reprogram the ECU. So then the argument that Mass air is better because it is adaptable to engine modification is no longer valid.

If you spend some time and look at guys running power adders many just junk the stock eec IV for Fast,AEM,SDS,Big Stuff the list goes on and on.

The key to the argument is context.

WORD.

 

[jbuening]

Does anyone know how hard it would be to add injectors to a carb manifold? I have a polished aluminum manifold that has bosses for injectors but wasn't sure how hard it would be to add the injectors. Down the road i too plan on going with a Megasquirt on my motor. Sure it's fairly easy to do a stock 5.0 EFI conversions on the 302 and smaller motors, but hood clearances become an issue when you have a 351W. TBI, MAF, SD, MPI, hell it's all better than a carb anyways. Either way you look at it you'll be custom tuning your EEC with any major modification to the motor. Besides, there's something trick about hooking up a laptop to your car to actually see what it's doing and it takes alot of guesswork out of troubleshooting.

How much support is there for the Megasquirt? I too am from the computer age (23 yrs old) and have had computer programming but i don't remember too much from that class. I wouldn't be a fish out of the water but i wouldn't know too much about programming either.

 

[rhyno9]

Does anyone know how hard it would be to add injectors to a carb manifold?

MSD use to make injector bungs that can be screwed into the manifold. More than likely the bosses you speack of are for nitrous jets. Generally the bosses are not large enough to fit injectors. So you will probably need to have bosses welded on to your aluminum intake (tig welded would be my recomendation). Personally I would spend the 350 and buy a super victor efi intake summit racing # EDL-29245 and then get the fuel rails summit # EDL-3620. Less then 450 for both and then sell what you have on ebay. Unless you have access to a mill and can tig aluminum it will probabaly cost at least 200 in machining costs plus the bungs.

How much support is there for the Megasquirt? I too am from the computer age (23 yrs old) and have had computer programming but i don't remember too much from that class. I wouldn't be a fish out of the water but i wouldn't know too much about programming either.

You don't need to "program" anything. Basically if you can solder (easy to learn anyways) you can put the thing together. Then you fire up the laptop and set the parameters using a software app called megatune.

There is lots of support at www.msefi.com

I would recommend purchasing from www.diyautotune.com as jerry is very helpful and each component is packaged in individual baggies which makes assembly a snap.

 

[Bullitt]

Does anyone know how hard it would be to add injectors to a carb manifold?

i also doubt you have injector bungs, just nitrous bosses.

there are 2 ways to modify your manifold for injectors, the right way and the cheap way. you can get your buddy at the machine shop to mill pockets for the injectors, fashion a fuel rail and mounts and have the same setup as you can get from Accel or Edelbrock (new, out of the box, for between $380 and $450 it looks like).

or you can buy a set of bungs from MSD/Kinsler Fuel Injection/etc, get a set of injector retainer clips and fittings, a bunch of braided hose and run a braided line to each individual injector. of course you also have to make a fuel distribution block that has 8 outlet ports, 1 inlet port, and depending on how you do your fuel pressure regulator a provision for that as well. you'll end up with a rather ghetto looking system that really probably isn't any cheaper than something off the shelf.

you can also send your manifold to a company like Force-EFI or Kinsler for conversion, but this runs minimum $200+.

it's a lot better to buy one off the shelf.

 

[88 Fox GT]

Speed Density is a pain in the ass! You must install a factory spec cam with SD, or else the vacuum changes and confuses the SD, not allowing the car to run correctly. Unless you want to spend the money on the software to tune it.

TBI sucks! This is why they used it for a limited time only. It's worse than a carb. As for driveability it's better, but for power it's worse.

What you want is multi port EFI with MAF. You can get systems that use a carburetor type of intake which have the injectors installed in it. Then, there is a throttle body that LOOKS like a carburetor that sits on top of that intake. It's not TBI, because there are 8 individual injectors mounted to the intake.

 

[ddonaca351]

No offense, but I'm wondering if you really know how both fuel injection systems work? Speed Density also measures the air coming into the system, it just does it a different way.

Speed density uses a MAP (manifold absolute pressure) sensor. It measures vacum in your intake manifold and calculates the fuel requirement based on the volumetric efficiency of your engine, RPM, and a default fuel map. It then uses the other sensor inputs to adjust the fuel injected (ie O2 sensor, coolant temp sensor, intake air temp sensor, throttle position sensor, etc). This is where you run into problems with large engine mods, as you end up changing the volumetric efficiency of your engine. However, the other sensors will still offer feedback and thus small changes do not effect performance.

Mass air does have some advantages. Mostly in the fact that it's a more direct way of measuring air, and thus adapts to engine changes better. It's also a little simpler to understand...

Speed density has advantages in that because there is no device measuring airflow, there is less restriction to airflow (more power). Also, mass air measures airflow by using a heated wire.. which in turn heats the air entering the engine(less power). Also this heated wire is prone to failure, and is a costly device. Mass air meters usually go for around $200 and need to be calibrated. MAP sensors cost $30 and do not need to be calibrated.

In some examples, speed density can be the more robust system. For example.. in a mass air vehicle, a vacum leak causes major greif. Simply because unmetered air is entering the manifold. With speed density all that happens is your engine idles too high.

It depends on the application and owner... but speed density does have some real advantages, and a blanket statement like "mass air is better" is not applicable. No more than saying "trucks are better than cars".

SD doesn't actually measure the air, it makes an educated guess based on the look up tables, but thats splitting hairs...

Either one has good and bad points.. (imho) SD is more forgiving of radical cams, major mods, etc...

Accel DFI, Gen 7, etc... are good examples of high quality systems

The MAF (again imho) is more adaptable to daily changes in conditions, but speaking as one who has a fair amount of time programming an EEC4 to run with cam, heads, intake, exhaust, etc... I can say that it is , ...um, ... "quirky", trying to get things like stable idle, etc... WITH good performance fuel and timing curves, lotts of cam, etc.

However if you had a good aftermarket MAF system, it would probably have these problems bread out of it, due to the nature of an aftermarket system.

Debating between SD and MAF is like debating one brand over the other (ford / chev / mop), neither is truly "better" it just depends on your personal prefference.

Dave- (ex SAE cert for emissions and fuel injection)

 

[Edbert]

Screw injection, put a carb on there, it's a '69 Mach1, they don't need no sewing machine motors! EFI motors just don't sound right on a classic to me, MFI maybe but not electronic.

Now back to your regualrly scheduled flame-fest

 

[ddonaca351]

Screw injection, put a carb on there, it's a '69 Mach1, they don't need no sewing machine motors! EFI motors just don't sound right on a classic to me, MFI maybe but not electronic.

Now back to your regualrly scheduled flame-fest

Yeah he's right, who needs great throtle response AND great power AND good emissions AND easy starting either ice cold or boiling hot.... screw all that modern technology! Put a carb on it and some bias ply tires like 6" wide and a 3 speed trans and youll have all the performance you can handle.


DD

 

[bnickel]

Yeah he's right, who needs great throtle response AND great power AND good emissions AND easy starting either ice cold or boiling hot.... screw all that modern technology! Put a carb on it and some bias ply tires like 6" wide and a 3 speed trans and youll have all the performance you can handle.


DD

if you really want all of the above and don't want to spend a ton of money put a 470 cfm autolite 4100 on it and install an electric choke an electric fuel pump and a fuel pressure regulator and forget it. you'll have all of the above for less than 300 bucks

 

[ddonaca351]

if you really want all of the above and don't want to spend a ton of money put a 470 cfm autolite 4100 on it and install an electric choke an electric fuel pump and a fuel pressure regulator and forget it. you'll have all of the above for less than 300 bucks

You must have missed the part about great power....
470 cfm = not near enough. (maybe dual 470's)

DD