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Dusty1
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PostPosted: Mon Aug 04, 2025 10:09 am    Post subject: Re: Engine build plan questions. Reply with quote

Zgecko wrote:
-It will be for a VW Trike so vehicle weight might be a factor.


You may want to pay attention here 'cuz this is life and death. No, I'm not bein' dramatic.

I've built dozens of motorcycles, may have turned wrenches on thousands by now. Who's counting?

More a stain on my resume than a feather in my cap, I'm an automotive engineer formerly employed by Chrysler.


Fuel economy isn't important when you're busted up or dead.


TRIKES COMBINE SOME OF THE WORST CHARACTERISTICS OF CARS AND THE WORST CHARACTERISTICS OF MOTORCYCLES.

To be specific something like 70% of your braking is accomplished by your front wheel or wheels whether you're on two, three or four wheels.

You're giving away most of that 70% by relying on one front wheel to stop a thousand pound vehicle. Yeah, some Harleys weigh damn near half a ton. That's why Harleys and Harley shaped objects aren't my first choice for chasing sport bikes on back roads or for dodging Grandma out on Main Street.

Your rear wheels only provide 30% of your braking no matter how well your rear brakes work. That may de- mystify the chopper crowd, the guys who would rather look cool than be safe. Those are the guys who run ten foot long springer forks (cool!)(I'm bein' facetious) and no front brake.

Don't worry about maintaining 70mph on a VW trike. The faster you go, the quicker you'll get hurt.


I was going to comment on aircooled VW fuel economy.

Ride safe.


oprn wrote:
It would be pretty hard to convince anyone that the street Buggy is farm use...


I think it's the other way around. An old VW can be more useful on the farm than a spendy side by side.

My old man used to strap ramps to the roof racks of the '79 Dasher I got for him. That way the walking tractor can walk its own fat ass into the back of the Dasher.

You would be surprised how many bales of hay fit into a Dasher.

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oprn
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PostPosted: Sat Aug 02, 2025 6:03 am    Post subject: Re: Engine build plan questions. Reply with quote

BFB wrote:
hey Oprn, not sure how Canada works as far as this goes, but from how it seems your buggy could be classified as farm use or farm equipment and the gas used in it an operating expense. in which case you'd have to be less concerned about the fuel mileage and those extra dollars counting.

I would have to be making money off my land to use it as a deduction against income. Also here farm fuel is without road tax if the vehicle is used for farm business which could be claimed to be the case for the sand rail. However there is a land size minimum and an income % minimum that leaves me out of that game. I only have 4.5 acres.

It would be pretty hard to convince anyone that the street Buggy is farm use...
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PostPosted: Sat Aug 02, 2025 3:59 am    Post subject: Re: Engine build plan questions. Reply with quote

Anyway, getting off topic. It would be nice to hear from the OP about progress on his trike project.
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PostPosted: Sat Aug 02, 2025 3:47 am    Post subject: Re: Engine build plan questions. Reply with quote

I do understand to a degree why builders don't tune them. In my experience the tuning can take as much time or more than the building to get right. I am also convinced that you will never get it right until it is in the car and on the road.

I have been tuning a street Buggy for a local fellow, we found out who originally built it (2 owners and 6 years back) and I have since become friends with him. This fellow's hobby is finding the parts and building them to sell. He is presently working on #69. He gets them to the point that they run ok-ish around town. He told me he has become very fussy about who he sells to. They must have a clue about mechanical things and old VWs in particular before they buy. "The warranty stops at the end of the driveway because I have no idea how it is going to be driven and maintained."

I totally get that considering the way this one was (not) running when I looked at it for my Buddy and the aftermarket parts that had been slapped on. I have been sharing my struggles with him and comparing notes on what was done to it since he last saw it. It just confirms his conviction that there are a lot of people out there that should not own one.

I went through the same struggle with my own Buggy when I first bought it. It was advertised as ready to drive. Ya right! It didn't stall (much) and all the gears, lights (sometimes) and brakes (one grabbed) worked...
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PostPosted: Fri Aug 01, 2025 11:07 am    Post subject: Re: Engine build plan questions. Reply with quote

Over here, a lot of people will take it to a rolling road to get it "set up", but all they get is a main jet change and the knowledge that it won't burn a piston at WOT. Costs about the same as an AFR install.

To be fair, they're all camper owners who just want to be back on the road and go camping without breaking down (again) - that to them is success. They think breaking down is normal for an old vehicle, along with wobbly steering, poor brakes and a strong smell of petrol.

Not everyone buys an old vehicle because they like tinkering. I asked one of my customers once to point at the carb, he had no idea though his wife knew. They'd owned it for about 10 years and were on their 3rd engine. Smile
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Brian_e Premium Member
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PostPosted: Fri Aug 01, 2025 10:47 am    Post subject: Re: Engine build plan questions. Reply with quote

oprn wrote:
I cannot understand the thought process that justifies spending $6K to $8K on all the best and biggest engine parts, all the chrome bling and yet baulks at another $120 for a wide band to get it all running right. All that outlay of cash, a 009 is fine and 15 to 18 mpg constitutes a good tune!


It happens WAY more than you think....and it doesn't make sense. Its even worse when builders charge 10k-12k for a fancy engine, but then they only break in on a stand with no load, or further testing. Leave it all up to the new owner to figure out.

That's why I mentioned it long ago in this thread. If MOST guys just bought a wideband, and learned the tuning on their CURRENT engine, they would be WAY further ahead than trying to build some new MPG specific boring engine.

The VW crowd is about the worst at getting it going, and thinking its awesome, but it barely starts, it stinks, hardly idles, and it gets 10mpg.

A little bit of correct tuning goes a really long ways. This is what John C. kept trying to drill into peoples heads for years.

Brian
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PostPosted: Fri Aug 01, 2025 10:24 am    Post subject: Re: Engine build plan questions. Reply with quote

I cannot understand the thought process that justifies spending $6K to $8K on all the best and biggest engine parts, all the chrome bling and yet baulks at another $120 for a wide band to get it all running right. All that outlay of cash, a 009 is fine and 15 to 18 mpg constitutes a good tune!
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PostPosted: Fri Aug 01, 2025 4:55 am    Post subject: Re: Engine build plan questions. Reply with quote

If we're talking about short-stroke, big bore engines running 009s and Kadrons through an EMPI Monza or similar -- then better mileage is 100% possible.

Use better carbs and a better ignition. Get a better header that's sized appropriately. Save your pennies and buy a wideband 02 sensor. Tune the engine.
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PostPosted: Fri Aug 01, 2025 3:45 am    Post subject: Re: Engine build plan questions. Reply with quote

A stock one doesn't keep up with the traffic, more oomph is required to stay safe. That's my start point, so getting more mpg is never going to be possible.
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PostPosted: Fri Aug 01, 2025 2:35 am    Post subject: Re: Engine build plan questions. Reply with quote

As far as what Brian_e builds and for whom I can't answer that but I do know that he does present some of the most practical advice on this site. Has he ever built an engine where the top priority is fuel economy? I will let him answer that one. That is the OP's top priority.

We all want more power. If anyone doesn't it's because they have never driven an air cooled VW in stock form. Can we have a sizable increase in power and still retain stock fuel economy in these 50 year old engines? That has been my goal and I am the first to admit that I have yet to achieve that. With Webers, crank trigger, wideband, gear ratio changes and lots of tuning and tinkering my mild street engine has gone from 18 mpg to the 28/29 region. That is still somewhat short of the 34 mpg my stock Beetle got back in the mid '70's.

I think there are two things standing in the way of achieving an engine with the best of both worlds. The first is the valve train. Any valve train that will give us a good kick in the butt at 6K RPM will have far too much friction and not be anywhere near efficient at a 2800 to 3000 RPM cruise. That is why I do not believe that a performance engine and a mileage engine are one and the same thing.

The second is what you stated 58 Plastic Tub, these old cars are just not aerodynamic enough.

The aerodynamics of a trike at 75 mph? I have no idea...
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PostPosted: Thu Jul 31, 2025 7:46 pm    Post subject: Re: Engine build plan questions. Reply with quote

Brian is not building dragsters, he's building street engines and doing the hobby a great service by posting honest, real-world information. He's also 100% correct. The payback for building a milage motor is "never", because you're spending dollars to chase dimes.

Regardless, the best mileage I ever got with a T1 was a twin-plug, dry-sumped 2276 with 45 Dellortos -- it would do 30 mpg if the planets were all lined up.

But (and there's always a "but"), it was in the Speedster replica with a .93/3.44 final drive, top down, on an Interstate highway through the Midwest in the summer. I think having enough power to start with, keeping the engine in a good state of tune, and pushing something light and sleek down the road is where you gain the efficiency -- and I've stayed at a Holiday Inn Express so I know what I'm talking about.

Most guys building "milage motors" go through a lot of gyrations to build an underpowered lump with a weird cam, then throw a 009 and Kadrons on the result. Kads are a glorified pump sprayer for gasoline -- they have no real tunability in transition, no way to dial in anything more than, "yep, runs great as long as we spray enough fuel". If you get real carbs (Weber or Dellorto) and learn to tune them -- you'll pick up 5 mpg, almost guaranteed. A real ignition will make every bit as much difference as the carbs. The result will be power AND milage.

Regardless -- even with good parts, if you don't have a wide-band O2 sensor, you're just guessing

My contention remains -- if you want mileage, build a powerful and efficient STREET combination. Efficiency is power -- the idea is to burn all of the fuel (or as much as possible) and convert the heat into motion. Guys looking for mileage want a complete burn. Guys looking for power want the same thing. It's not either/or, it's both/and.

Most VWs have the aerodynamics of a brick. The only "free" place to pick up mileage is to make the car as aerodynamic as possible. Nobody thinks about that, but there's more to be gained there than anywhere else.
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PostPosted: Thu Jul 31, 2025 3:57 pm    Post subject: Re: Engine build plan questions. Reply with quote

Now that I am retired we are down from about 75,000 to 80,000 km a year to about 45,000 km. About 6 to 8,000 of that is in our street Buggy in the summer. The rest is in our Jetta TDI or the wife's 2.0 L Golf. The Buggy has the worst fuel economy at 28 to 29 mpg, the Golf next at 34 to 36 mpg followed by the Jetta at 54 to 56 mpg. This is all Imperial gallons so take 20% off that for US gallons.

Gas is hovering around $1.50 per liter at the moment so $6.83 a gallon. You can at least double the savings that Brian_e quoted. Realistically it will be about $2000 next year just for next summer at a 3 mpg gain.

My wife retires next spring and the plan is to spend our summers touring around western Canadian points of interest and between the our 4 children so the miles put on it will at last double, possibly triple. Mileage is not the only consideration, range is too. At the moment we are limited to 3.5 hours between fills. About the same as a Tesla! There are many places we travel that you are hard pressed to find fuel on that regular of a basis.

I deeply regret not putting a TDI in this Buggy when I switched engines. I did not because it would have turned it into a rolling junkyard from behind. I do have a line on an MG TD replica for sale. If I buy it I will sell the Buggy and the MG's 1500 SP and drop a TDI in the front out of sight.

We live in a different world than you guys do as far as expenses and distances travelled. So for those of us that drive these things there is a lot more to "performance" than knocking 0.3 seconds of a few 1/4 mile runs.
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PostPosted: Thu Jul 31, 2025 2:49 pm    Post subject: Re: Engine build plan questions. Reply with quote

oprn wrote:
You are right. For the most part the VW crowd are a bunch of hobbyists that don't give two farts about throwing money at the pumps for the reasons you stated. There are a few of us of more limited means that have to make each dollar count but still want and enjoy these old relics.

We unfortunately are a pain to those with deep pockets because we keep asking questions that the usual crowd have no answers for aside from "It's all in how you drive it." which in reality is code for "I don't know and don't really care".

I find it interesting that no expense/effort is too much to find 2 or 3 HP but 2 or 3 mpg... not worth it.

Fair enough. We don't all have the same interests and priorities. No offence meant, just an observation.



Ok, so be honest, and tell people how many miles your driving in the average month. Whats your monthly savings if you gain 2 or 3 miles per gallon?
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PostPosted: Thu Jul 31, 2025 1:50 pm    Post subject: Re: Engine build plan questions. Reply with quote

oprn wrote:
I find it interesting that no expense/effort is too much to find 2 or 3 HP but 2 or 3 mpg... not worth it.


Like you said, its a hobby. Hobbies are supposed to be fun. Spending forever tuning an old car to get another 2-3MPG isn't much fun, but 2-3 more HP IS fun. Very Happy

I did the quick math's, driving 10,000 miles per year, which is a BUNCH for most people here, and using $3/gallon fuel cost.

At 25mpg you would use 400 gallons, and spend $1200.

At 30mpg, which is a BIG increase in fuel economy, you would use 333.3 gallons, and spend $1000 for the year.

That's ONLY $200/year difference, or $3.85/week. Most people spend twice that on a cup of coffee in a day. I don't have "deep pockets", but would much rather build a more fun engine, or drive my engine harder for the $3.85/week.

I just don't see the point of going out of the way to build a MPG specific engine for a toy, when the $$$ savings are really minimal at the end of the year. I CAN see buying a wideband, learning tuning theory and trying to super tune your current engine.

If someone is looking to get a bunch of MPG out of an old VW, skip the '40's tech aircooled, and go get an '85 diesel rabbit.

Brian
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PostPosted: Thu Jul 31, 2025 1:45 pm    Post subject: Re: Engine build plan questions. Reply with quote

hey Oprn, not sure how Canada works as far as this goes, but from how it seems your buggy could be classified as farm use or farm equipment and the gas used in it an operating expense. in which case you'd have to be less concerned about the fuel mileage and those extra dollars counting.
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PostPosted: Thu Jul 31, 2025 1:20 pm    Post subject: Re: Engine build plan questions. Reply with quote

I don't think the OP has said what MPG they are looking to realistically get?
15 to 20 years ago Hot VW's had a mileage motor series (advert for CB) where they got mid to high 30's with a 1745 in a bug.
I would guess that to get much more than that with a bug would require a newer engine design than one that was conceived 90 years ago.

If mileage is the ultimate goal, a 1L Suzuki 3 cyl from a Geo Metro in a trike should net 60+ MPG with 50-60HP and that is with 30+ yr old tech.

Personally, I don't give two farts about mileage.
But I am one of those that haven't ever since my Dad & Uncles street raced and they sold (gave) me my first car for $50 which was a retired SC police interceptor with a 427 and helped me rebuild it.
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PostPosted: Thu Jul 31, 2025 12:13 pm    Post subject: Re: Engine build plan questions. Reply with quote

You are right. For the most part the VW crowd are a bunch of hobbyists that don't give two farts about throwing money at the pumps for the reasons you stated. There are a few of us of more limited means that have to make each dollar count but still want and enjoy these old relics.

We unfortunately are a pain to those with deep pockets because we keep asking questions that the usual crowd have no answers for aside from "It's all in how you drive it." which in reality is code for "I don't know and don't really care".

I find it interesting that no expense/effort is too much to find 2 or 3 HP but 2 or 3 mpg... not worth it.

Fair enough. We don't all have the same interests and priorities. No offence meant, just an observation.
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PostPosted: Thu Jul 31, 2025 11:07 am    Post subject: Re: Engine build plan questions. Reply with quote

oprn wrote:
Brian_e wrote:
Most every time someone goes and tries to build a MPG specific engine, they make a bunch of sacrifices, and end up with a boring engine that might get 2-3mpg more than something way more fun. Brian

True enough but does it have to be that way or are we just inexperienced at that game?


It doesn't need to be, but from my experience, people either refuse to accept modern tech, such as a 123dist., they refuse to learn how to tune it within a gnats ass, or they just plain give up.

There is a crazy amount of learning and engine theory that needs to be done to squeak that last 3-4mpg out. Even if a guy does build an engine that will get a real 34+mpg, carefully driving, and never exceeding 55mph, how many miles is he actually going to drive the thing? I think there are very few people around the aircooled world that put on a real 800-1000miles per month year round. At 3000 miles per year.... why even bother? Bragging rights just so you can compare your car to a prius??

I drive my aircooled cars 1000+ miles per month almost year round. I could car less if it gets good MPG. They are toys, I drive them like a 16 year old, and I am not unhappy about the extra $5 per month it costs me at the pump. I just want them to put a smile on my face on the way to work each morning.

Brian
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PostPosted: Thu Jul 31, 2025 10:34 am    Post subject: Re: Engine build plan questions. Reply with quote

Isn’t about 80% of fuel economy found under your right foot? (Or in this case, twisting of the right wrist?)

If mpg is what you’re after, you can always get a Prius, head straight for the #1 lane, and drive 15 under the limit. Works great for some people…
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PostPosted: Thu Jul 31, 2025 4:17 am    Post subject: Re: Engine build plan questions. Reply with quote

Brian_e wrote:
Most every time someone goes and tries to build a MPG specific engine, they make a bunch of sacrifices, and end up with a boring engine that might get 2-3mpg more than something way more fun. Brian

True enough but does it have to be that way or are we just inexperienced at that game?
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