Want to Build Ultimate MPG Motor

Guest · Post by **Guest** » Tue Oct 19, 2004 11:45 am

Jake, can you give us your secrets on that 1600 T1 with good gas mileage?

72_square · Post by **72_square** » Tue Oct 19, 2004 12:40 pm

He's staying quiet so far

I guess I would to, if I'd put so many hours into testing and proving such engines. Wouldn't want to give away all the trade secrets.

I was hoping for a few clues though...

brianwheelies · Post by **brianwheelies** » Tue Oct 19, 2004 1:16 pm

so guys, what about building a bigger motor and carb it down and small heads and cam? should not require much revs and hopefully not consume too much fuel.

Post by **Marc** » Tue Oct 19, 2004 1:25 pm

That's one of the many projects I have ahead - have a nice set of late Beetle FI heads (33x30) that I want to try with some small dual carbs on a 1641 or 1775. It seems to me that a near-stock cam would work well with slightly wider lobecenters to reduce overlap but I'm not sure that the difference would be enough to justify the expense of a custom-ground cam.

72_square · Post by **72_square** » Mon Oct 25, 2004 12:53 pm

How about breaking this down into engine parts then....

Getting the fuel into the engine, which is best (for economy):

Rigging up some kind of D-Jet or similar fuel injection
Single, central carb (stock or a webber)
Dual carbs

In my limited experience, the stock single carbs are ok, but not fantastic on mileage. I have used a single 32/36 webber progressive and gotten very good mileage (30mpg on average) with a light foot, certainly better than stock.

I've run dual FRD34 dellortos on a bug 1641cc engine before and got quite poor mileage (23-25mpg in UK gallons). It was set up right.

I'm installing, but not yet run D-Jet on my type three square. Everyone says that I'll get better mileage than carbs full stop.

I'd like to go for a type three D-Jet on a bug, but it will take some fiddling. it is worth the hassle? Anyone like to add some input on the fuel economy characteristics of any of the above? Keep those ideas coming...

CHAZAVW · Post by **CHAZAVW** » Mon Oct 25, 2004 1:05 pm

i have 71 super with a 1914 that is built mildly with weber 44idfs with 145 mains. and i get 28 mpg on the highway, the key is the light foot......

i have an engle 110 cam. with 1.25 rockers. cb 044 heads with 40 X 35.5 valves. 8.72 to 1 c/r i run 93 octane only..... just a force of habit.

caxambas · Post by **caxambas** » Tue Oct 26, 2004 6:56 am

My brother put a type 3 D-jet on his beetle a few years back. Stock motor except 1647 cc. Runners were modified with plenum up in the middle. The car did 32 miles a gallon very consistently. The power was nothing better than a 1600 with 34 PICT Solex. I would say that a set of stock dual type 3 carburettors on a beetle would be more worth your time.
Jos

72_square · Post by **72_square** » Sun Oct 31, 2004 6:20 am

Found a bit more info on that Jon Karcey engine from the early '80's, need to order some Hot VW's back issue to get the full report though (unless any kind soul can scan copies in for me

)

Karcey used a 'square' engine, one with bore approx the same as stroke. He used a 76mm counterweighted crank with 77mm bore 1300cc pistons. Rimco case with a web cam (don't know what grind). Stock 1300cc heads (don't know if single or dual port). Heads were fly cut for 9.0:1 compression (scarey!). Kadron dual carbs with 25mm home made venturis and 100 main jets, 009 dizzi. Standard tyres. He also added a heavier custom front pully. Weight of pully, flywheel, crank = 50pound +. Also used Amsoil products for less friction. Ported & polished heads and used total seal rings. Also used a spearco water injection system

This is all good info. I'm suprised he used a 009. Thought a stock dizzi with vacuum advance would be much better. Seems that the 'square' engine and a nice heavy rotating mass helps a lot.

My thoughts are to follow in a similar vain but 'modernize' it with:
Fuel injection
Stock vac dizzi
Decent CDI ignition
Anti-knock sensor (if I can afford it!)

Not sure on the 9.0:1 compression, guess that's why he ran the water injection, damn hot. Maybe something just over 8.0:1

Murdock · Post by **Murdock** » Sun Oct 31, 2004 10:14 am

If you are talking about the Karcey 50+mpg '68 Ghia, alot of information from the 1982 article is different than you described.

Centerline light-weight rims were used on all four corners
Tires were 145x15 and 155x15 (ads says 146x15- typo I'm sure)
Airdam for improved aerodynamics
Weber ICT carbs with 24mm vents & elec. idle cutoff jets
Heads are stock 1300cc with "minor" porting only on exhaust side
cam has "less duration than stock, with a little more lift than stock, rate of opening a little quicker than stock and lobe center has been altered"
Distributor is a Bosch 205 vac-retard, total advance at 2400rpm
Pulley is from a Jaguar XK-E (extra weight + overdrives fan)
Compression is listed as 7.9:1 running leaded premium
1st and 2nd gear are higher ratio, 3rd is stock, 4th is .82, r&p is 3.88 (article says 3.81 r&p but that can't be right, they also list gear sizes as .082 and .073- all misprints I'm sure.)
At the time of writing Karcey was working on a .73 4th gear to achieve 58mpg
MSD 5-C.D. ignition and blaster coil
no mention of water injection

I wasn't trying to be an a$$ but where did you get the info you posted? Could it be a previous combo before the one published in the magazine? Does anyone know what happened to the plans he sold to Southern Volks in Grand Prairie, TX? I don't think the shop is there anymore because I would live 5 miles from it!

72_square · Post by **72_square** » Sun Oct 31, 2004 12:57 pm

Murdock

Thanks for the extra info. I got my info from trawling The Samba.com, it pointed me here:

http://www.southernvolksfolks.com/tech/46mpg.html

I guess this was his early days try out and he refined it later to your spec. Was he still running a 76mm crank?

Until now, I've only heard rumours and bits and bobs about the Karcey engine. Hot VW's is special mail order in the UK, so not much chance of finding those early 80's articles. I think I've managed to track someone down in the USA who will copy the pages for me.

Anyone got any clues as to why a shorter duration/higher lift camshaft would be better?

Murdock · Post by **Murdock** » Sun Oct 31, 2004 8:30 pm

Ah I see, thanks for the link, I didn't have that one! My article came from a 1982 VW & Porsche July/August issue I believe- so that must have been his earlier attempt.
I do believe the crank is still 76mm, I know the pistons were 77mm but the article said something along the lines of 77mm pistons from a 1800cc engine, but since he used 1300cc heads, the pistons and cylinders would be the best bet in my book, the 1800cc thing might be another typo!

mschilling · Post by **mschilling** » Tue Nov 02, 2004 7:44 am

When I bought my wife's 65 it came with a 36hp engine. I was surprised at how it moved the light car around with ease and could maintain a decent cruising speed on the hwy. With that tiny 28 stock carb, the fuel economy was excellent. What would be probably a better choice would be the stock 40hp engine. That's the one that made the bug so famous for economy and million mile records, trips to the north pole, etc. It's in the combo, and VW got it right with the 40hp. Why re-invent the wheel? By comparison the dual ports suck mucho gas.

caxambas · Post by **caxambas** » Tue Nov 02, 2004 10:13 am

You are absolutely right.The 40 hp 1200 was so good that this motor was available in europe on all beetles up to the end of production in 77. It was even available on the late model super beetle convertibles in Italy because of taxation issues. These motors were peppy and reliable and good on gas.
Jos

72_square · Post by **72_square** » Tue Nov 02, 2004 12:32 pm

Yeah, the 1200cc is a good engine, but fuel economy was still only around the 30-35mpg mark at best. My goal is to get slightly better than that by mixing and matching components and tightening up the tolerances. It may end up based around a 1200cc engine, or something slightly bigger perhaps. The idea of this thread was for people to chip in with what they thought brought out the best MPG in a motor. I agree that single ports work better for fuel economy; I'm tying with the idea of trying to make a fuel injection system work either with single or dual port heads.

Guest · Post by **Guest** » Tue Nov 02, 2004 3:55 pm

You want a high velosity engine. small to medium stroke, probably smallish bore to get a complete burn. If you go with a small stroke you can go with more compression because you can take better advantage of squish in the head. Always go with the lightest wheels you can. Vacuum advance is a must too. Small dual carbs of EFI. cool air induction. Dont go too high on compression so you dont need super unleaded (defeats the purpose ,right?) You need lots of bottom end grunt.