TheSamba.com :: View topic

Sat Jul 06, 2013 8:45 pm

I'm considering building a 2000cc plus engine and I would like to know what kind of mileage you guys are getting if you keep your foot out of it. I want to build one for a daily driver beetle. Thanks.

Sat Jul 06, 2013 9:10 pm

Get the trans gearing high enough there is no reason it would not get great MPG's Highway!

Sat Jul 06, 2013 9:31 pm

30~35.but there are a lot of variables.

Sat Jul 06, 2013 9:36 pm

There are SO MANY variables besides engine size that determine what kind of mileage you will get; too many to go into here.

BTW, simply gearing your car higher to lower rpm on the freeway is no guarantee that you'll get better mileage. The key is to get the rpm at freeway speed to match where the engine runs most efficiently. VW geared their trannys in 4th gear purposefully. The stock engines made their peak torque/power at a certain rpm. If you LOWER that rpm the engine has gotten out of is power curve, and what happens is you need more pedal to keep the same speed - like going up a slight grade - which causes the engine to work harder, run hotter, and burn more gas. The whole "freeway flyer" trans thing is really not true. Think about it... In 1970 Beetles came from the factory with a 4.12 R&P and a 4th gear ratio of .89. In '73 they started using a 3.88 R&P, but switched their 4th gear ratio to .93. Why did they do this? IMHO gearing a tranny in a Beetle w/ a 3.88 R&P with a .82 4th gear is a bad idea.

Sat Jul 06, 2013 11:07 pm

My roommate had a 2276cc engine with FK-8, 44 x 37.5 ,street eliminators, 1 3/4" exhaust and 48 IDAs was able to achieve 24 mpg without a lot of effort.

Sat Jul 06, 2013 11:17 pm

I understand that there are many variables. I've read a lot in this forum about big street engines running 44 and 48mm carbs. I was wondering if you can get good mileage on such a big engine with huge carbs? I would like to build a 2110 (76mm x 94mm) for my 63 but it will be used as a daily and would like to have my mileage in the mid to high 20's at least.

Sun Jul 07, 2013 5:30 am

Fuel injection will get you there....

Sun Jul 07, 2013 5:31 am

miniman82 wrote: Fuel injection will get you there....
Agreed.

I have a 2180 FK8 dual IDAs and get 28mpg, but i have a 5 speed.

Sun Jul 07, 2013 7:17 am

76X94 = 2109
82X90.5 = 2110 and is actually .4cc larger.

A well tuned 2110 you should be able to get 30 MPG. It will last longer and run cooler then the 2109.

MPG is mostly based on your driving habits. I feel it is a huge mistake to change to taller gearing. The VW factory got the gearing correct. Your '63 came with a 1200cc engine and a 4.37 R&P gear. You need to upgrade to a '67 & later transaxle with the 4.12 R&P gear.

You can get just as good MPG with correctly jetted & tuned dual carbs as you can with EFI. You will get better MPG with a vacuum advance dist then you will with a mechanical only dist.

For the best MPG you need to drive 60 MPH or slower. MPG drops horribly the faster you drive above 65 MPH. Keep all your junk out of your trunk. A lighter car will get better MPG then a heavier car. Properly inflated tires are also very important.

Believe it or not a roof rack will kill 2-3 MPG. Adding a Herrad Helper can get you an extra 2-3 MPG.

Sun Jul 07, 2013 8:52 am

vwracerdave wrote: You can get just as good MPG with correctly jetted & tuned dual carbs as you can with EFI. You will get better MPG with a vacuum advance dist then you will with a mechanical only dist.

Caveat: you must tune with a wideband oxygen sensor for best results.

Sun Jul 07, 2013 9:03 am

I would think VW went to the taller tran gearing because of the gas shortage in the 70's then and then went back to closer to unity gearing for passing on the freeways and to keep up on the hills.

Taller gearing will help save fuel, especially if your increase the displacement, I have heard of 1835 cc engines getting 42 mpg just running really big back wheels.

Sun Jul 07, 2013 9:25 am

Edited.

Never mind.

I got 40mpg @ 70mpg out of a 12.0 second bug. 31.1 out of a bus doing 4000rpms.

But feel free to tell me i'm doing it wrong. lol

Sun Jul 07, 2013 9:32 am

hmm peek torque??? and that is at about where? and why do you need that?? in a buss posibly but not a bug unless it is pulling somethen or draging somethen.but if your motor is under powered your mg will suffer, if it makes good power ittell be just fine, the farther you push that peddell the more fuel it will use if tuned properly,and I dont think it takes a lot of torque to push a bug down the road,atleast not mine.

Sun Jul 07, 2013 9:34 am

I often wonder why gas millage even comes up in the same subject of big "cc' performance motors....

Dale

Sun Jul 07, 2013 9:41 am

Dale M. wrote: I often wonder why gas millage even comes up in the same subject of big "cc' performance motors....

Dale

I like the challenge of it. No other practical purpose.

Mid 20's is easy to get with a half-decent tune on a stroker motor.

Sun Jul 07, 2013 9:49 am

You guys arguing for taller gears; think about it from an engineering perspective. If you've gotten the engine out of it's best power range by lowering the rpm you have not helped yourself at all, bug, bus, or long haul 18 wheeler. The vehicle is irrelevant.

Sun Jul 07, 2013 2:25 pm

[quote="vwracerdave"]76X94 = 2109
82X90.5 = 2110 and is actually .4cc larger. Quote:

I guess it depends on how you do the math (pi symbol vs. .0031416), but I only got a .2cc difference (2109.7 vs 2109.9)

Sun Jul 07, 2013 2:35 pm

Eaallred wrote: Edited.

Never mind.

I got 40mpg @ 70mpg out of a 12.0 second bug. 31.1 out of a bus doing 4000rpms.

But feel free to tell me i'm doing it wrong. lol

31 MPG's out of a Bus? that's hard to believe, Sounds like a Dream. What kind of engine was that?

Sun Jul 07, 2013 3:40 pm

Danwvw wrote:

31 MPG's out of a Bus? that's hard to believe, Sounds like a Dream. What kind of engine was that?

1600 single port. Stock gearing and 1.36 reduction boxes. 65mph at 4000rpm.
Was still 6 volt and ran the stock oil bath air filter. Stock single tip exhaust too.

I got 28mpg doing 65mph out of my 64 Deluxe geared for 4000rpm @70mph
26mpg doing 65mph out of my old 79 Westy with stock 091 trans (4000rpm @75)

Was a handful of years ago, so maybe it was a dream.

My next project is to see what a 10 second turbo car gets for gas mileage after i'm done tuning it. And it will run 91 octane too, lol

Sun Jul 07, 2013 5:15 pm

Dale M. wrote: I often wonder why gas millage even comes up in the same subject of big "cc' performance motors....

Dale

Because what is the point in driving a tiny car with a huge engine that get as good mileage as a big car with a big engine?
I was just asking before I go that route. I've built many high performance engines. Mostly chevys and 36hp based.