A14 B210 better mpg than L16 510: Quench?

[Cardinal Grammeter]

I had a 72 510 and a 74 or 76 (I can't remember) but I do remember it was an A14, not an A13 so what, maybe a 1976?

 

Anyhow, the A14 OHV got 44 mpg on the Interstate while I don't think the L16 SOHC could get 30 mpg rolling down hill.

 

One would think that the newer SOHC would get better mpg.

 

Does anyone know what the quench is on those motors?  If not, perhaps the deck height and gasket thickness?

 

If the quench is nice and tight (.035), there will be better HP and mpg due to ability to run higher CR and/or more timing.

 

Thanks

Tom

[ggzilla]

The A-engine came out 1966

L-engine came out ... 1965

 

The major reasons for better fuel economy are 1) smaller aerodynamic frontal profile and 2) reduced friction.

[datzenmike]

B-210 is lighter too. Every hill the engine has to lift the weight of the car vertically and every time the car is accelerated to speed... that takes gas energy. I had a new '76 and only twice got it below 30MPG. On a trip across Canada I got a couple of tank fulls well into the 40s.or 50s it was so high I thought it a mistake. Canadian Imperial gallon though.

[izzo]

Man I miss my B210. That thing got crazy gas mileage. 

 

I drove a little over 1400 miles in my 510 wagon with L16, weber, dogleg, matchbox dizzy and spent about 150 bucks in gas back in 2010.

[ggzilla]

1976 B210 4-speed was EPA rated for 41 MPG highway. Since Datsun speedometers have +5/-10% tolerance, it explains why you observed 7% better economy back in the day.

[Cardinal Grammeter]

Yes, a B210 was light but a 510 was light too.  I don't think any of them are under 2000 lbs.

 

One would think the OHC would be the superior technology.

[datzenmike]

1976 B210 4-speed was EPA rated for 41 MPG highway. Since Datsun speedometers have +5/-10% tolerance, it explains why you observed 7% better economy back in the day.

 

And there is over half a liter more in the Canadian gallon. This translates to 49 MPG. So it was over 50MPG!

[ggzilla]

Light? Weight has no appreciable bearing on highway fuel economy. Aerodynamics and friction do. Lightweight engine parts do. Smaller engines win out over larger due to less pumping losses (ie the throttle is open more at the same hp).

 

Now when talking about city fuel economy its almost the opposite.

[datzenmike]

On a level highway at constant speed not much. Bicycle up an incline with a passenger and tell me it doesn't appreciably take more effort than by yourself. Hell, any incline by yourself for that matter. Of course it does. You are lifting weight through a vertical distance every time you drive up an incline. True, some speed can be recycled on a down hill to run up the next, but this isn't always the case. All things equal, the lighter car will always give better mileage.

[ggzilla]

Not on the old EPA highway ratings. Or for the 300 miles between Portland and Vancouver. Its nearly flat and nonstop. Car wight has negligible effect.

 

Riding a bicycle on the same road makes me tired too.

[datzenmike]

My point is the in the REAL world it's different. Way different. We don't drive in the EPA world. Portland to Vancouver BC is certainly not flat... like prairie flat. There are always ramps and inclines no matter how short or high, you still have to climb them over a vertical distance and that takes energy.  Lighter car gets better mileage.

[ggzilla]

You are right. The b210 gets 41 MPG on that stretch, but with an extra 200 lbs only gets 40.8 MPG.

 

1976 B210 weighs 2000 lbs. What does the 510 weigh?

[datzenmike]

About 2,000 lb, wagons almost 2,200 ish

[datzenmike]

B-210 is lighter too.

 

Ah I see. The B-210 is not appreciably lighter then. Then better mileage is in this case the motor design, aerodynamics, less friction. (probably radial tires too?) I thought the B-210 was much lighter. 

 

I still maintain all things equal the lighter car get better mileage. I guess neither has a weight advantage in this case.