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Old 03-27-2013, 11:59 AM
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Mechanical Fuel Injection

Hi,
I am thinking of using mechanical injection on the street. I'm thinking a
6-71 with a birdcatcher hat, it would be on a mopar 440. What I'm conserned with is cylinder wash and oil getting dilluted. Does anyone know a few things about this style of injection? Oh, I also want to run E85.

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Old 03-27-2013, 12:45 PM
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This is from Hilborn:

A Hilborn mechanical injector is classified as a constant flow system and was designed to operate at WOT under load. As a constant flow system, pressure and volume are controlled by the main jet, or pill, along with pump speed (engine rpm) and nozzle size. The barrel valve, which controls idle fuel and transitional fuel from idle to WOT, can be compared to a ball valve much like the one that turns off the water in your house. The basic design and lack of fuel control of a barrel valve does not allow us to control the fuel at part throttle especially no load part throttle. If you consider the fact that an engine's fuel requirements are based directly on load, and that we can have many different loads at different rpms all at the same throttle angle, the lack of fuel control for street applications becomes apparent. A mechanical system does not employ enough fuel control in the operating range where you drive your street car and, therefore, is not recommended for street use.
Of course we have all heard the stories of mechanical system working on the street but few if any actually worked correctly. The use of a dial-a-jet, additional bypass valves, and home center ball valves have all been used to provide fuel control for adequate street use, but fall far short of the fuel control required as part throttle load is constantly changing. The constant manual adjustments needed, as one guesses the current fuel requirements of the engine, leaves very little time to actually drive the car and, at best, is incredibly inaccurate. Blown applications appear not to be as affected by the lack of fuel control of mechanical injection, possibly due to the load placed on the engine to drive the blower, but is still not recommended for those looking for the best all around drivability.
The use of alcohol helps because of it's large tune-up window, but fails to provide drivability due to loading up, mileage (in gallons to the mile) and severe oil dilution. Claims from those that run injected engines on stands or dyno's stating they can make mechanical injection streetable, are unable to simulate a fraction of the different part throttle load scenarios your engine will see, nor provide the required fuel control. Interestingly enough, engineers have devised a way to electrically control these valves and bypasses...it's called electronic fuel injection.
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Old 03-27-2013, 01:29 PM
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Quote:
Originally Posted by 46studebaker View Post
Hi,
I am thinking of using mechanical injection on the street. I'm thinking a
6-71 with a birdcatcher hat, it would be on a mopar 440. What I'm conserned with is cylinder wash and oil getting dilluted. Does anyone know a few things about this style of injection? Oh, I also want to run E85.
While it may not be as "cool" to you EFI is cheaper, MUCH more controllable and will lead to better power and DURABILITY.

Of course seeing how your entire plan consists of obsolete and outdated parts I'm guessing this is for show only, and you won't be able to brag about using mechanical injection.

You can make it work good enough to get to the local burger joint for a show, if that's all you want I wouldn't worry about it.
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Old 03-27-2013, 11:01 PM
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Mechanical Fuel Injection

Thanks for the info. I still have a little to think about. And Yes, it would be for show more than anything
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Old 03-28-2013, 12:06 AM
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As 33 explained the success rate of this working is very close to winning the lottery. There have been a very few that have made these sorta work but even so they have an astounding fuel consumption. You can lower the fuel pressure but you then give up atomization. The blower helps here a little but it can only do so much. These mechanical systems were made for racing at full throttle and to idle for a few seconds before WOT.

Using an EFI is much easier and cleaner. Even these still have problems keeping an accurate fuel mixture. It takes a lot of messing around to get it right.

It's very easy to get a 6-71 to run with carbs. Even these take a little special effort to get right to reliably run on the street. When they are right they are lots of fun.

Mine runs great even on 87 pump gas and I get pretty good mpg. It's right on the edge however and it take constant monitoring.

If you want a show car, I think you will find the attitude that if it doesn't run half way decent at the show it is not very popular.
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Old 03-28-2013, 03:41 AM
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Mechanical Fuel Injection

Thankz for the great informations....
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Old 03-28-2013, 05:42 AM
How fast is fast enough?
 
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Quote:
Originally Posted by bentwings View Post
As 33 explained the success rate of this working is very close to winning the lottery. There have been a very few that have made these sorta work but even so they have an astounding fuel consumption. You can lower the fuel pressure but you then give up atomization. The blower helps here a little but it can only do so much. These mechanical systems were made for racing at full throttle and to idle for a few seconds before WOT.

Using an EFI is much easier and cleaner. Even these still have problems keeping an accurate fuel mixture. It takes a lot of messing around to get it right.

It's very easy to get a 6-71 to run with carbs. Even these take a little special effort to get right to reliably run on the street. When they are right they are lots of fun.

Mine runs great even on 87 pump gas and I get pretty good mpg. It's right on the edge however and it take constant monitoring.

If you want a show car, I think you will find the attitude that if it doesn't run half way decent at the show it is not very popular.
I think you accidentally swapped efi and carbs. A carb doesn't come close to the ease of use nor the reliability of efi. But a carb can work decent enough with enough fiddling.
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Old 03-28-2013, 07:49 AM
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Agreed, mechanical injection is not suited to street use. it makes more horsepower than any other method of induction, though. This is why it's the only kind of injection used at the highest levels (T/F, N/F, TA/D. TA/FC. etc.). Most use Waterman or Enderle today. but Hilborne is still "out there".

EFI is much "cleaner" and drivability can't be beat. As long as you keep power requirements reasonable, EFI can "keep up", too. We've seen bigger engines "dry up" some of the more popular EFi systems.

Jim
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Old 03-28-2013, 12:18 PM
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Quote:
Originally Posted by Mr. P-Body View Post
Agreed, mechanical injection is not suited to street use.
To clarify, CONSTANT FLOW mechanical injection is not suited to street use. There were a whole bunch of Corvettes and European cars built in the 1950s and 60s with mechanical fuel injection that ran on the street.

Quote:
Originally Posted by 46studebaker View Post
And Yes, it would be for show more than anything
If you're only looking to be a poseur, just get one of these:

STREETINDUCTION - Dummy Hilborn-Crower 8 Stack Fuel Injector Style Cover, Mounts over 4bbl Carburetor,

Seriously, you can get one of the Hilborn-style manifolds converted to EFI with the injectors towards the inside of the stacks, so they don't really show that much. Runs MUCH better than mechanical and still looks very cool. Just be prepared to bring dumptrucks full of cash to get one made.
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Old 03-28-2013, 12:46 PM
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Joe's right. GM's mechanical system (Chevy called it "Ram Jet", I forget what Pontiac called it) is so old, I didn't figure we were "talking" about that. We learned in the '60s, a 650 Holley on a "high rise" would easily out-power it on a 327... Sorry...

Jim
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Old 03-28-2013, 01:57 PM
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Quote:
Originally Posted by Mr. P-Body View Post
Joe's right. GM's mechanical system (Chevy called it "Ram Jet", I forget what Pontiac called it) is so old, I didn't figure we were "talking" about that.
I knew what you meant, but one thing I've learned is that if it's at all possible for someone to misinterpret a post on an internet forum, they will.
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Old 03-28-2013, 08:11 PM
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Quote:
Originally Posted by Mr. P-Body View Post
Agreed, mechanical injection is not suited to street use. it makes more horsepower than any other method of induction, though. This is why it's the only kind of injection used at the highest levels (T/F, N/F, TA/D. TA/FC. etc.). Most use Waterman or Enderle today. but Hilborne is still "out there".

EFI is much "cleaner" and drivability can't be beat. As long as you keep power requirements reasonable, EFI can "keep up", too. We've seen bigger engines "dry up" some of the more popular EFi systems.

Jim
Mechanical fuel injection doesn't even cut it for top fuel any more. Nowdays a slide valve is used in conjuction with all the other parts of a mechanical injection. The slide valve is a variable fuel return which is controlled by a computor.
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Old 09-02-2013, 09:48 AM
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mechanical fuel injection

Hello,
Back again.
I have chosen to go a different rout for now, I didn't have the money to get the supercharger done and purchase a birdcatcher and everything that goes along with getting it to work.

I did find a "Rons Flying Toilet" that is complete and ready to run, Which is another form of mechanical injection.

I have been running a holley 850 double pumper with NOS, and now that I installed the toilet and tuned it, it feels like I'm running the NOS all the time with the previous set up. It seems to have pretty good street manners as well.

Very happy so far, thanks for the info again
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