Holley Sniper EFI fuel economy

[Tohm]

So I picked up my truck with a sniper EFI already installed on a 350. Call me greedy, but I wouldn't mind getting better fuel economy out of it. I ran down all the usual suspects and it doesn't appear to be running rich or lean yet I'm averaging approximately 8-10 mpg. From what I've heard that is about par around here.

Anybody else have a sniper EFI fitted? What kind of fuel economy are you getting? Worth retraining?

-Tohm

 

[Frankenchevy]

It’ll only get so far on the self tuning. To get the best out of it, you’ll need to fine tune with the software.

Does your c10 have a th350? Which rear gear?

Keep in mind, the sniper isn’t going to be much better than a well tuned QJ for mpg.

 

[bluex]

If you haven't done it you can adjust the afr settings to help some. Making it a 2d table helps most but you'll have to do that with the software.

I can get mine to about 17.5-18 on the highway which isn't a ton better than the carb I had before. The benefits from these units are in other areas imo.

 

[Tohm]

It’ll only get so far on the self tuning. To get the best out of it, you’ll need to fine tune with the software.

Does your c10 have a th350? Which rear gear?

Keep in mind, the sniper isn’t going to be much better than a well tuned QJ for mpg.

I guess I'll have to figure out how to fine tune it. Its a 700R4 with I think a 3.08. I can run out and check it another time.

 

[Ricko1966]

What's your timing set at? Is the vacuum advance functional and hooked to manifold vacuum. People forget what a big part those 2 play in power and mpg.

 

[bluex]

Here is a decent start to a 2D table for stock or mildly modified SBC.

You must be registered for see images attach

 

[GTX63]

If you haven't done it you can adjust the afr settings to help some. Making it a 2d table helps most but you'll have to do that with the software.

I can get mine to about 17.5-18 on the highway which isn't a ton better than the carb I had before. The benefits from these units are in other areas imo.

Cold starting would be probably #1, better fuel distribution and simpler tuning with gas mileage down the list a bit. Personally, I still prefer the pump and gun contraption that was mass produced by Rochester. But mods and driving habits are always a factor, ie gearing, tires, your right foot.

 

[Ricko1966]

We had a member not too long back,crappy gas milage. All the usual go EFI, Go Qjet,blah,blah,blah. After 4 pages and I don't know how much time m,he finally fixed his timing issues,mpg more than doubled,and could have done more,if he put in more work to make it right,not just acceptable. I don't think you can expect those kind of results,but you need to look at timing especially if you know your afr is right. If you have working EGR look for a little over 50 degrees at cruise on the highway,no EGR a little under 50 degrees.

 

[SquareRoot]

Sniper....

 

[bluex]

We had a member not too long back,crappy gas milage. All the usual go EFI, Go Qjet,blah,blah,blah. After 4 pages and I don't know how much time m,he finally fixed his timing issues,mpg more than doubled,and could have done more,if he put in more work to make it right,not just acceptable. I don't think you can expect those kind of results,but you need to look at timing especially if you know your afr is right. If you have working EGR look for a little over 50 degrees at cruise on the highway,no EGR a little under 50 degrees.

If he's running timing control through the sniper then he definitely needs a 2d table an a real timing map there too.

If it's an HEI then hopefully he's got it on the correct port for manifold vacuum an the base timing set for his cam.

 

[mntman71]

If you have an HEI distributor you need to check your timing and vacuum. I would look at the hyperspark if you don’t have it already. I am running the sniper terminator max with the timing controller and transmission controller. I went from 6-8 mpg to 8-12 ( if I keep it under 65 mph and my foot out of it). Before I was messing with the Qjet and timing weekly. ( my transmission went out is also a factor why I switched, installed a 4l80E that was laying around). I have not had any issues after the initial advanced timing and set up. I’m running 4:10 gears, locker and 35” tires on a K20.

 

[Mogulmasher]

There's definitely something out of tune somewhere. A c10 with OD auto and 3.08 gears should do better than that mileage with a carb.

 

[Tohm]

We had a member not too long back,crappy gas milage. All the usual go EFI, Go Qjet,blah,blah,blah. After 4 pages and I don't know how much time m,he finally fixed his timing issues,mpg more than doubled,and could have done more,if he put in more work to make it right,not just acceptable. I don't think you can expect those kind of results,but you need to look at timing especially if you know your afr is right. If you have working EGR look for a little over 50 degrees at cruise on the highway,no EGR a little under 50 degrees.

Thanks. I don't have any experience in timing but this seems to be a consistent item that I'm told should probably be addressed. I'll add it to the list.

 

[Tohm]

If you have an HEI distributor you need to check your timing and vacuum. I would look at the hyperspark if you don’t have it already. I am running the sniper terminator max with the timing controller and transmission controller. I went from 6-8 mpg to 8-12 ( if I keep it under 65 mph and my foot out of it). Before I was messing with the Qjet and timing weekly. ( my transmission went out is also a factor why I switched, installed a 4l80E that was laying around). I have not had any issues after the initial advanced timing and set up. I’m running 4:10 gears, locker and 35” tires on a K20.

This is optimistic for me then. Hopefully I can manage at least 12 mpg.

 

[Tohm]

Here is a decent start to a 2D table for stock or mildly modified SBC.

Thank you, sir!