Builds 1985 FJ60 Gets a Holley Sniper EFI Setup (5 Viewers)

[FirstFJ60]

The Sniper replaces the carburetor

No mileage improvements

Im just curious why wasnt there any mpg improvements when EFI should be more efficient than a carb?

 

[wngrog]

Im just curious why wasnt there any mpg improvements when EFI should be more efficient than a carb?

Not necessarily. It’s a one size fits all system.

 

[cps432]

Im just curious why wasnt there any mpg improvements when EFI should be more efficient than a carb?

It’s not the same as direct injection where each cylinder gets its own squirt of fuel. It functions as a carburetor but is controlled by a computer rather than vacuum. The intake is designed for a carb which requires a pulse to keep things flowing. This may effect the sniper’s efficiency to some degree but I don’t know enough about those fluid dynamics. Cleaning up a rough casting would probably do more for fuel efficiency than anything else. Also, running the correct oil will improve MGP.

 

[FirstFJ60]

It’s not the same as direct injection where each cylinder gets its own squirt of fuel. It functions as a carburetor but is controlled by a computer rather than vacuum. The intake is designed for a carb which requires a pulse to keep things flowing. This may effect the sniper’s efficiency to some degree but I don’t know enough about those fluid dynamics. Cleaning up a rough casting would probably do more for fuel efficiency than anything else. Also, running the correct oil will improve MGP.

Thanks for the break down...makes sense. Im just trying to justify the Holley Sniper when my carb works great w/o being desmogged.

 

[zipper]

Thanks for the break down...makes sense. Im just trying to justify the Holley Sniper when my carb works great w/o being desmogged.

starting and running sideways are definite advantages. in really cold weather you are on the go much quicker when finally tuned. think of it this way, if merely adding FI added MPG, they wouldn't have had to redesign entire engines.

that having been said, the engine will generally run smoother with a more consistent mixture. MPG may go up a tad if your carb was just dumping in fuel, or... it may actually go down if you were running leaner than you thought you were.

then there's the problem of pre existing conditions, that you were just driving along with a carb, and didnt know. that stumble you felt previously, may be a leaky valve or something that the sniper spends all its effort trying to correct and driving you bananas as to why it wont tune up easily. you SHOULD fix those things, sure, but sometimes, what you don't know won't hurt ya for 80,000 miles on a 40yo engine.

overall I'm neutral on the recommendation if you don't wheel.

 

[Anthony Miller]

My O2 sensor is in the "test pipe" cat' area at 1:30 position. View attachment 3182228View attachment 3182229
What's whis fuel prime multiplier?
To me 5 minutes to swap in another Bosch unit. The wires are the perfect length to avoid the exhaust and throttle stuff. The poor girl might be suffer from "short distance driving syndrome". I've been averaging 6.1 miles per day.

That idle AFR is pretty rich. I think mine is 14.0-14.2.

 

[LimuEmu]

Im just curious why wasnt there any mpg improvements when EFI should be more efficient than a carb?

We are also talking about a glorified tractor motor in all reality! I'm just happy I don't have to pull the choke any more

 

[MoaByte]

That idle AFR is pretty rich. I think mine is 14.0-14.2.

Yes, way more rich than I thought it should be. This was recommended by Holly tech because of stalling issues after engine braking before a stop. I have yet to get it tuned by the laptop method. I'm getting some smoke from worn valve seals now that I suspect is playing hell with the O2 sensor. Sniper can't get to set AF levels, varies from too lean to too rich daily. I got a spare head to get prepped, that had better fix it.

 

[MoaByte]

Im just curious why wasnt there any mpg improvements when EFI should be more efficient than a carb?

It's more efficient at turning bad gas mileage to more power. If you are used to driving a smogged 2f, you will appreciate the difference. If your engine doesn't have even and good compression, EFI is not a good idea. The carb is more forgiving and EMP resistant. Plus you have a cool lighted choke cable to scare the kids.

 

[zipper]

That idle AFR is pretty rich. I think mine is 14.0-14.2.

naa.. thats fine. its just idle, and that fuel will keep the o2 from hunting around and going lean with the s***ball uneven airflow on the 1930's manifold design when you come off a long slow deceleration. keep in mind if you put a modern oem engine management system on this engine, the airflow is so uneven cylinder to cylinder at any given cycle, it would likely go "robbie the robot" and self destruct. A good engine may be .5 higher, but these aren't good engines when new.

 

[zipper]

Here's what I've wondered... with a carb the fuel is a constant flow with the venturi effect, and with a FI you're pulsing. What effect does that have at what RPM when combined with the manifold?

I think at high RPM it doesn't mean s*** with the volume and turbulence, and thats why even when out of tune these run decent under load/cruise, BUT when idling, the lower you go the more it matters, and trying to run a lean fuel mixture with a 600-650 rpm, things start to get a bit wobbly with the crappy airlow of the manifold causing inconsistent burns cylinder to cylinder and the O2 trying to make corrections. The well tuned JinC carb on the other hand? There's no O2 to get befuddled, and by constantly metering in fuel, there's always fuel available to each cylinder as it wants it, and youre able to tune a super low rpm. (This constant fuel flow would also make it harder to stall, as theres no "catch up" after a long grade decelerating in gear, when the computer kicks back in and sees a super lean AF.)

The end result being, the engine idle runs better with a tad rich AF and 750-800 rpm idle. I would think this would be exacerbated by an aftermarket performance cam ****ing up the vacuum.

The intake isn't designed for FI. notice how Big T went from carb straight to port on the 3fe, and skipped the TB tech altogether? having taken this route, I now bet theres a reason for that.

 

[b56tc]

That is a really logical analysis. And helpful with creating expectations.

I've been digesting this thread over the last several weeks as I am really at a point of considering re-carb'ing. Your comments help understand why I'm not realizing a "EFI transformation experience" with this engine. It has been anything but - you want simple and so far all that is simple is not pulling the choke knob and 4 less turns of the engine at crank. After that, for me, it has been Mr. Toad's Wild Ride with the infinite tuning possibilities and domino effect of changing one parameter waaaay beyond this junior mechanic and tuner's grasp.

Getting a bald spot from head scratching. I've got a fresh bored balanced beautiful desmogged headered 2F(I) (official 60 race engine) which has to be putting out at least 6 more hp than stock but rather than burning up rubber at the strip I'm constantly dealing with cold engine stumbling, near stall then recover when returning to idle, and milking the throttle to accelerate.

Just frustrated this am. And logging information and suggestions for a strategy when i pull it out of storage after the salt is off the roads and tackle it again.

I would haul it to a tuner or expert at this point as it would be nice to just have it to drive this season

 

[Zjohnsonua]

Carbs and throttle body injection systems are both wet plate designs - making them both susceptible to the same problems of poorly atomized fuel, especially while cold.

Fuel atomization doesn't see real gains until you get to port or direct injection.

 

[zipper]

A couple additional things i'll note that were fighting here, is the amount of RPM band were dealing with, and volume of air required for the power produced.

first, the sniper (at least my "2bbl" model) comes set up, and is expected to be utilized, on an engine that has 40% more usable rpm. I tried making a map that would mirror the expected basic V8, but with an RPM band much stumpier, and that level of detail wasnt appreciated by this engine, it would hunt like crazy.. What is running great, is a map barely more complicated than the "idle, cruise, wot" it comes with just to get the damn thing to turn over. i actually suspect many people just leave it at that factory setting, and the blind squirrel may have found a nut with that approach.

WOT on this is for a 300hp v8, not a 120hp 6, of similar volume. tip in is way to fast, so i made a lever arm i attached to the linage with a 5 different positions so i could limit the air more. i think if i recall i settled on about 70% actuation of the valves. it also provides a control advantage when you have the gears i have. I was going to tear apart a gm tbi for the cable cam, but i didnt want to risk breaking the holley as there's some press fit s*** on it.

 

[wngrog]

All my Snipers are run on the stock settings.

 

[brian az]

All my Snipers are run on the stock settings.

Me too. I mean, I only have one, but still, it’s all stock settings.

I sometimes get the stalling when I stop with a cold engine. But I’ve found that if I just don’t push in the clutch until I absolutely have to to, I can avoid the stalling.

 

[Zjohnsonua]

I sometimes get the stalling when I stop with a cold engine.

This. So annoying. I've seen it on multiple engines with similar workarounds.

 

[MoaByte]

A couple additional things i'll note that were fighting here, is the amount of RPM band were dealing with, and volume of air required for the power produced.

first, the sniper (at least my "2bbl" model) comes set up, and is expected to be utilized, on an engine that has 40% more usable rpm. I tried making a map that would mirror the expected basic V8, but with an RPM band much stumpier, and that level of detail wasnt appreciated by this engine, it would hunt like crazy.. What is running great, is a map barely more complicated than the "idle, cruise, wot" it comes with just to get the damn thing to turn over. i actually suspect many people just leave it at that factory setting, and the blind squirrel may have found a nut with that approach.

WOT on this is for a 300hp v8, not a 120hp 6, of similar volume. tip in is way to fast, so i made a lever arm i attached to the linage with a 5 different positions so i could limit the air more. i think if i recall i settled on about 70% actuation of the valves. it also provides a control advantage when you have the gears i have. I was going to tear apart a gm tbi for the cable cam, but i didnt want to risk breaking the holley as there's some press fit s*** on it.

I modified the stock linkage arm for direct linkage and have great tip in and 70% WOT. I did add a return spring. It works very well both crawling and on the road. I can feel the engine twist in the mounts corresponding to pedal induced torque.
I am not completely happy with the sniper but I'm not throwing in the towel. If I knew then what I know now, I'd have just sent the carb to Jim.
Considering V8 swap and moving the sniper over to the 20R truck.

 

[wngrog]

Me too. I mean, I only have one, but still, it’s all stock settings.

I sometimes get the stalling when I stop with a cold engine. But I’ve found that if I just don’t push in the clutch until I absolutely have to to, I can avoid the stalling.

I have one that does it pre-160. The second it hits 160 it won’t do it.

That one is at 680 rpm though. Looking above at the guys with the big brains maybe I’ll bump it to 750.

 

[MoaByte]

I have one that does it pre-160. The second it hits 160 it won’t do it.

That one is at 680 rpm though. Looking above at the guys with the big brains maybe I’ll bump it to 750.

That's what Holley tech asked me to do.