Fuel consumption with Webers

[Eriks]

I'm upgrading my L18, but I'm warned against high fuel consumption.

 

What fuel consumption should I expect when normal use of the 510 when using:

 

a ) Weber 32/36

b ) Weber 38/38

c ) Twin 40 dcoe

[datzenmike]

That's like asking how long is a piece of string.... it's subjective. The 32/36 can be carefully tuned to be close to the original Hitachi carb for mileage. If your Hitachi was flooding or worn out and giving crappy mileage then the weber will give better.

 

The 38/38 is a 6 cylinder carb and too big for an L18 unless heavily modified. Always go with a smaller carb than one that is too big.

[Zeusimo]

I Get 10 MPG With My Lead Foot :)

[kelowg]

Dgv 32/36 on  LZ21, 18-20 mpg. Driving like a mad man at 75-80mph up to yosemite.

[datzenmike]

I Get 10 MPG With My Lead Foot :)

 

 

Dgv 32/36 on  LZ21, 18-20 mpg. Driving like a mad man at 75-80mph up to yosemite.

 

 

Proof that there is no real answer to this. What ever you dot with your Hitachi you can get close to with a 32/36

[Eriks]

I appreciate your replies, thanks. Yet I have to specify "normal use".

Virtually all car manufacturers and reviewers estimate fuel consumption from a given car with a given engine with a given fuel delivery system under normal use of the vehicle.

Is that less possible when the car is a Datsun 510 with a L18 with a Weber ?

[Mikeystoy]

I never really drove my Courier with the Hitatchi; but others report 28mpg consistently. I get 18-21 driving normally (out of the secondaries) My Cricket (A14/A60 5 speed 3.90 gears) got 30-32 with the stock carb (but GUTLESS) and 28-31 with the 32/36.

My Pinto (2.3/auto) gets 20 with a 32/36 driving EASY

[datzenmike]

.

I appreciate your replies, thanks. Yet I have to specify "normal use".

Virtually all car manufacturers and reviewers estimate fuel consumption from a given car with a given engine with a given fuel delivery system under normal use of the vehicle.

Is that less possible when the car is a Datsun 510 with a L18 with a Weber ?

There were no estimates for a 510 with an L18 because they were never made or tested.

 

Tests would be based on the stock Hitachi carb and webers were never used on them.

 

L18s were used on the early 710 and the '74 620 truck .What ever the L18 was rated at, the weber will be no better and almost without exception, less.

 

 

You can ask people that have a stock L18 in their 510 and a 32/36 weber what their mileage is. This would be much better than an... estimate.

[EricJB]

If you are the least bit concerned with mileage, go with the 32/36.  I'm willing to put up with a small amount of loss with a Weber DGEV. I think Hitachi's are poo. JMO.

[Eriks]

I'm sure many of the members here have experience with Webers and fuel consumption on L-engines. I'd like to hear from them.

[Stoffregen Motorsports]

I just saw this thread and haven't read any of the replies, but I noticed the tag line and couldn't resist.

 

Fuel consumption with Webers?

 

YES.

[EricJB]

My 521 ( 48 DCOE's) eats 3/8 of a gallon per 1/4 mile. does that count? 

[Eriks]

My 521 ( 48 DCOE's) eats 3/8 of a gallon per 1/4 mile. does that count? 

 

It sure does :) Thanks.

[datzenmike]

My 521 ( 48 DCOE's) eats 3/8 of a gallon per 1/4 mile. does that count? 

 

What engine though?

[EricJB]

Ya, sorry, I'm no help here. I haven't had an L18 in anything in 20yr's. And I never checked the mileage. I would guess 22 to 24. DGEV.

 

Not sure how you drive a car with DCOE's "normal" . I ran some 40 DCOE's on an L20, and would guess 16 to18mpg. 

[Stoffregen Motorsports]

Not sure how you drive a car with DCOE's "normal" .

I couldn't have said it better myself. If you buy an AR15 for hunting, you're lying to yourself. You like the gun and you found a way to justify it.

 

Same with dual carbs. If you run dual carbs on a well tuned engine, you can't tell me you aren't floored at least 30% of the time.

 

So the mileage question is just a way to justify the expenditure to our wives.

[Eriks]

Ya, sorry, I'm no help here. I haven't had an L18 in anything in 20yr's. And I never checked the mileage. I would guess 22 to 24. DGEV.

 

Not sure how you drive a car with DCOE's "normal" . I ran some 40 DCOE's on an L20, and would guess 16 to18mpg. 

 

Eric, you may say that you're no help. But you tried, and thats awesome :)  Thanks !!

[datsunaholic]

I got close to 30 MPG, sometimes exceeded,  with a L18 in a '76 620 King Cab with a ZX 5-speed.  That was by being a featherfoot, and the truck had no acceleration, but ran great on the freeway.

 

The exact same carb- not just another 32/36, but the SAME piece of hardware,  on a different '76 KC with an L20B and the stock 4-speed gets around 24MPG.  I get the same mileage with a 38DGAS on a '74 shortbed with a 5-speed, but that one also can get into the teens if I accelerate hard.   Long trips sometimes get better, but being my commute alone is 45 miles, a "long trip" is usually going through a whole tank between stops.  And those usually get done at 70+ MPH which is past the optimal MPG for these things. 

 

Compared to Hitachis, I've gotten anywhere from 16 (my Mom's bone stock '73 620 with ear-splitter 4.88 rear gears)  to 35 (my '78 510 hatchback, also stock).

[Ranman72]

stock L16 no matter how I drove it with a 32/36 weber 24 MPG

My built L20 big valves big cam duel DCOE 40 webers 17 average 

driven like I stole it around 14 to 15 

[slowlearner]

Zombie thread! ☠️

 

Been trying to sort out the best milage tune for my L18, with stock internals and EFI. Checked it today and it's done 223miles for 9.19gallons. 

 

That's 24.26mpg if my maths is right. 

 

Apparently that's 9.69L/100km. 

 

Ok, so there was some WOT action, but I didn't think that much. Of course just after filling up, I discovered 3 of 4 tyres had under 20psi in them. So that wouldn't help. I was hoping for something like 30-35mpg. Am I kidding myself?

Edited March 11, 2023 by slowlearner

[datzenmike]

It's pretty much too hard to determine an average MPG of city and highway driving. I just go with highway driving and accept that this is the maximum best and therefore less than this on average. I assume this is like Canada and uses Imperial measure? Well we used to.

 

 

I've driven long trips with multiple tank fills of US gallons and my L20B gave 36.018 MPG converted to Imperial (that was a best and most were around 33) or just a hair under 30 MPG US.  So if that is in US gallons you are at about 33 MPG Imperial.

 

If 24.26 IS in Imperial gallons MPG then about 20 MPG US. That's possible with city and spirited driving mixed in. For highway driving that's simply put... low.