New guy with Classic Mini
 

Hey,

I own a 1982 Austin Mini (recently rebuilt) and have always had an eye on getting good fuel economy once the car was finished. It has a Austin Metro 1275cc engine and runs premium, carbureted with a 32/36 DEGV Weber. Has electronic ignition and has gotten a usual 28 mpg.

Pics! :D (think you need five posts to share pics, tho)

So yours is a mini Mini? ;)

Welcome to the fun, I'm looking forward to seeing what yours can do!


http://www.cardotcom.com/photos/news...i-carlo-01.jpg

Welcome to the site. I'm sure we can help you bump up that 28 mpg.

Have you checked out the 100+ hypermiling tips link up top? Its the easiest and quickest way to improve fuel economy.

[QUOTE=Fat Charlie;507481]So yours is a mini Mini? ;)

Yes, not a Cooper but its one of the little ones. Pics to come, I've got to downscale the resolution.

Thanks everyone, what's a good target mpg?

Here ya go!

http://ecomodder.com/forum/attachmen...1&d=1455748206

36 for now; when you hit 36, go for 40. I believe those numbers are possible with that car.

Love those old minis. They seem to go pretty good with a honda engine swap from a 92-00 civic or 94-01 Integra!

40 would be a dream, I can't wait to get that!

yes the honda would be fun as well, i know that the mounting bracket is $2k though hahaha. But the honda engines can be very efficient from what I've heard.

But the power from the 1275 is soooo enticing. With that little flyweight car wrapped around it, the engine just begs to be pushed.

Yeah, I think 40 is doable. Your carb setup might be too much for it though.

Injection or a smaller carb? I have a SU HS4 sitting here that came with it :D

Sweet Aunt Jemima, I have no idea. Never ever turned a wrench on a Mini, or any British car for that matter.

I bet it'd be a lot of fun though.

Been researching the carbs, thisis what I got:

Weber 32/36 - 320 cfm, 3-3.5 fuel psi

Su HS4 - 133 cfm, 2-3 fuel psi

The 1275 just needs just 134 cfm at 85% VE!

The later minis could come fuel injected. Would it make sense to swap EFI on it?

Well, based on those numbers it looks pretty clear to me that you're over-carbed. You might be getting poor fuel atomization/fuel burn due to low flow rates.

Have you had it smogged? That could tell you more.

No smog yet, need to go to the next city over as we don't have it here. Is the over carb that bad for milage? I'm new to carbs still too, just picking up what I'm finding.

If you get the SU working right it will beat the Weber easily. The first 240Zs with dual SU type carbs would do close to 28 highway. They ran lean enough that they were undrivable without manifold preheating under 55 degrees.

That "told" you they were set up about perfect.

Half the carb 1 for half the displacement no toilet accelerator pump, good old variable venturi with single point fuel delivery.

regards
mech

How much gain are we looking at with a SU? That would be a dream come true to be up near or at 40 mpg.

It would make sense, but the kit for injection is $2k before getting the ecu tuned. Where I'm at now I have no ecu lol

Too much carb is pretty bad for mileage, yeah.

If you're running wide open all the time for racing it's less of an issue as the air flow through the carb gets up to useful velocities. But when you're just motoring you need a more modest setup.

With too much carb, you're wasting some of the engine's energy pulling a vacuum against the inside of the throttle butterflies when you're tooling around at lower speeds. The low velocity gives poor fuel atomization (already mentioned) so you have to run rich just to get enough fuel to burn in the cylinder to keep you going down the road. It's a cascade of problems that all stem from too much carb and result in bad fuel economy. The rich condition might not be as bad as all that if the carb is set up carefully, but I bet it's a little smoggy when it's running.

You watch. You put the SU in and your torque peak should move pretty far down the rev band where you can use it more conveniently in daily driving. If the Weber was set up correctly you're probably going to feel the loss of some top end power, but the engine should be a lot more drivable. If you've been running smoky, switching in the right carb should reduce that.

For what it's worth, the Weber 32/36 is a recommended aftermarket replacement for my truck, which has almost literally twice the displacement your engine has. If it's a good carb for an engine that size, then you have to be either revving the nuts off a smaller one all the time to make use of the Weber's capacity, or else it's just more than a daily driver can use effectively.

Ah okay, I use the mini in town, but highways are the main way to get to and from work daily.

would it matter if I was at 4500' for the swap? Or just play around with the tuning to allow for elevation?

Considering the higher altitude I have no idea exactly what to recommend. If it were me I would be inclined to swap in a modest EFI system and a turbo tuned for light boost at lower revs, enough boost to compensate for the reduced air density and maybe a couple of pounds extra for funsies :D

Thanks for this pic! It shows exactly how non-mini today's Mini is:(

Efi for sure down the road, want to get top milage I can while still having fun. Not sure how boost works yet, but bit by bit I'll learn

If you're thinking boost...

Mighty Car Mods recently built a classic Mini with a modern Mini supercharger:
https://www.youtube.com/watch?v=evBxi9EPhDc

May or may not be helpful to you, but likely worth a watch.

How hard would it be to use the ecu and wiring from an obd1 honda 1.6? Would be significantky cheaper and since its obd1 probably little to no security on the ecu.

Mighty Car Mods is always worth watching.

40 MPG should be pretty easy. The SU might get you there by itself. Some inlet heating, and a few other easy mods ought to get you beyond that. I just built a hot or cold ram air inlet for my Vibe, but it is too soon to have any results to report. I have a 1963 Austin Mini 850 Super Deluxe and used to get 45 MPG all the time with it. BMC took a Mini on a promo lower 48 tour, and got 50 MPG back when nobody cared. The Mini design was prompted by the 1956 Suez canal thing. Good Luck!

Yes! I loved that series, their sister channel is doing an awesome double unicorn build too!

I will watch that one. I enjoyed this video! https://www.youtube.com/watch?v=hpb2Him9CUo

It is not a Mini, but I hope they gave them the same treatment!

My first car was a Mk3 sprite 1098 in 1969. Got 30 mpg driving as hard as I could. Always liked the Mini's.

Gas was 20-30 cents per gallon.

My brother just restored a 1969. He yanked the anemic Mini motor and dropped in a Honda V-Tech. Lets just say according to him the car is a real handful with liberal use of the go pedal. :D

I never asked him what the gas mileage is but it has to be pretty good considering the car weighs less than 1500 lbs. :thumbup:

Cam?
 

Whoever put that carb on it was not interested in mileage. I'd check to see if it has a hot cam to go with it. You can buy that engine down to 850cc for the economy versions, and it isn't too comfy internally when over 1100.
You probably want to get rid of the fender flares. Unfortunately, the easiest solution for streamlining is an Ogle body, and they are a bit thin on the ground now. Rounding the front, reducing the intake and de-seaming the A pillars would help. Going to a 1-box shape with a more raked windshield might halve the cd.

Throw the Weber over a hedge and fit a decent single SU - a 1 and3/4 inch would do fine
don't mess about with twins!

As far as fuel efficiency is concerned the old 1275 A series is an incredibly efficient unit, I don't think any of the modern engines get anywhere near the same thermal efficiency so replacing it with a Honda will give more power but worse MPG

The biggest efficiency improvement would be a higher final drive - mini's used to have a 3.44:1 final drive but you could buy a 2.9:1 - that makes a BIG difference to mpg

Three decades ago I had a 1275 bored and stroked to 1425cc in a mini with a soft top - that was a fun car!

Sorry, you just hit one of my pet peeves: VTEC is Honda's "pick a cam on the fly" technology. V-Tech is a crappy phone.

I believe that you either have to put very wide fender flares on the Mini to fit a Honda B-series drivetrain, or you have to slide the car in half lengthwise to make the whole thing wider.

-soD

Hi ALS
I bet the Honda engine really worked good on the Sprite. Thanks for sharing. The longitudinal engine worked well. Especially replacing a 48 hp turd. I would like to find a nice sports car to mount my 1.6 diesel in.

I really don't believe that 1950's designed 4 banger was "that" efficient.

I really don't believe that 1950's designed 4 banger was "that" efficient.

The hand of God was on that design!

Very thermally efficient - very good at converting the heat into power,

modern engines are much much more efficient at producing more power - but a lot of the techniques to get more power actually reduce the thermal efficiency

Mini guy, welcome to the forum. You may not have the access today that I had back in 1969 but I found a Morris Minor intake manifold and single side draft SU carb gave me a consistant 40mpg in my Austin Healy 'bug eye' Sprite. It is probably a little more streamlined than the mini but probably about the same weight and the conversion was quick. I only stuck it on the bug eye for about a month because I got tired of the loss in performance & gas was waaaaaay cheap back then!

Just a warning from the previous comment

You can't just put another SU carb on it - not if you don't want to burn a piston or waste a lot of gas

You need to set the carb up to your engine on a rolling road
SU carbs use a superb metering system using a tapered needle in a jet - there are about a thousand different shaped needles,

On my 1430 mini I changed the intake manifold - just the intake manifold - that made enough difference to melt a hole in a piston

Any carb fitted to a non standard engine will need to be properly set up on a rolling road