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-   -   Fuel economy transmission swap (https://forums.tbforums.com/showthread.php?t=342568)

Lando 06-07-2018 08:48 PM

Fuel economy transmission swap
 
I have a pedal cluster, clutch cable and cross member from a manual 240 for a manual swap on my 86 245, but I don’t know what trans I want to swap to. I have a bone stock B230F, that I don’t plan on modifying, I just want a manual transmission to improve my highway fuel economy because I know the AW70 is the main contributor to my 24mpg at best. I commute in freeways where the traffic is going 80+ mph.

What is the latest and greatest swap that people are using considering that I don’t need it to tolerate a whole lot of horsepower? I do not want an M46/47. I’d prefer a hydraulic clutch, but I’m not set on that. The T5 isn’t really calling my name either, but the WC variant does have some nice ratios for decent MPG at 80+ mph. I remember readying about some crazies entertaining the idea of a 6 speed Nissan tranny, but had trouble finding the thread.

JohnLane 06-07-2018 09:08 PM

Convert to 10 year old Corolla for 35mpg, less noise, better reliability, more likely hood of survival in a big accident ect.

For those of us with a thing for Volvos.... M-46 if it is healthy will do just fine at stock power level.

Seriously... If fuel economy is changing your lifestyle.... Work harder or smarter!

John V, outside agitator 06-07-2018 09:18 PM

Quote:

Originally Posted by Lando (Post 5808795)
I have a pedal cluster, clutch cable and cross member from a manual 240 for a manual swap on my 86 245, but I donít know what trans I want to swap to. I have a bone stock B230F, that I donít plan on modifying, I just want a manual transmission to improve my highway fuel economy because I know the AW70 is the main contributor to my 24mpg at best. I commute in freeways where the traffic is going 80+ mph.

What is the latest and greatest swap that people are using considering that I donít need it to tolerate a whole lot of horsepower? I do not want an M46/47. Iíd prefer a hydraulic clutch, but Iím not set on that. The T5 isnít really calling my name either, but the WC variant does have some nice ratios for decent MPG at 80+ mph. I remember readying about some crazies entertaining the idea of a 6 speed Nissan tranny, but had trouble finding the thread.


Careful...I heart all to fawk the T5--the one with the tallest 1st but I also reccomend much shorter axle ratios...
See its an interplay...1st thru 4th fun, and then when you have the insane overdrive of .63 or .72 AND a 4.3/4.37 or even a 4.88--then 5th is allright--on the flat and level>

4.88 back x .63 is 3.07 overall and that's pretty tall..Fine for a turbo car.

But that 5th and a 3.7 is 2.33 and that is nutso tall..So tall you'd be fighting wind resistance at 80+ and being below reasonable torque...so that would probably cost you Em Pea Gees.

As crazy as it sounds increasing the POP per pop --efficiency---all other things being equal--is the key to happiness.

My daily has a M47 and here everybody hates them --just like in the Mare_koooor world everybody "hates" the stock Type 9...Me? I say ""Hmmmmm not too bad for a daily/road car.."
Only problem with both is a) getting a good one or b) getting the parts to run thru the box spiffing it up before install..and getting them for reasonable cost... c) getting good info in the climate of "they're sh!t" which is the reflexive response..

Make manual trans grate again!

Lando 06-07-2018 09:26 PM

Quote:

Originally Posted by JohnLane (Post 5808806)
Convert to 10 year old Corolla for 35mpg, less noise, better reliability, more likely hood of survival in a big accident ect.

For those of us with a thing for Volvos.... M-46 if it is healthy will do just fine at stock power level.

Seriously... If fuel economy is changing your lifestyle.... Work harder or smarter!

Itís not changing my life style. My AW70 is shifting hard and I want a third pedal. I would also like to maximize my fuel economy. Thanks!

Lando 06-07-2018 09:28 PM

Quote:

Originally Posted by John V, outside agitator (Post 5808810)
Careful...I heart all to fawk the T5--the one with the tallest 1st but I also reccomend much shorter axle ratios...
See its an interplay...1st thru 4th fun, and then when you have the insane overdrive of .63 or .72 AND a 4.3/4.37 or even a 4.88--then 5th is allright--on the flat and level>

4.88 back x .63 is 3.07 overall and that's pretty tall..Fine for a turbo car.

But that 5th and a 3.7 is 2.33 and that is nutso tall..So tall you'd be fighting wind resistance at 80+ and being below reasonable torque...so that would probably cost you Em Pea Gees.

As crazy as it sounds increasing the POP per pop --efficiency---all other things being equal--is the key to happiness.

My daily has a M47 and here everybody hates them --just like in the Mare_koooor world everybody "hates" the stock Type 9...Me? I say ""Hmmmmm not too bad for a daily/road car.."
Only problem with both is a) getting a good one or b) getting the parts to run thru the box spiffing it up before install..and getting them for reasonable cost... c) getting good info in the climate of "they're sh!t" which is the reflexive response..

Make manual trans grate again!

Those are my concerns with the M46/47. I don’t want to go to a ton of trouble to put a worn out transmission that I can't find parts for in my car. I also hate the electric overdrive.

Cwazywazy 06-07-2018 09:38 PM

Will an M46 OD unit bolt to an M47?

JohnLane 06-07-2018 09:40 PM

Quote:

Originally Posted by Cwazywazy (Post 5808818)
Will an M46 OD unit bolt to an M47?

Nope

Cwazywazy 06-07-2018 09:42 PM

Quote:

Originally Posted by JohnLane (Post 5808819)
Nope

What if you use a lot of glue?

Lando 06-07-2018 09:44 PM

Quote:

Originally Posted by Cwazywazy (Post 5808820)
What if you use a lot of glue?

It'll glue on, it just won't bolt on.

John V, outside agitator 06-08-2018 01:10 AM

Quote:

Originally Posted by Lando (Post 5808816)
Those are my concerns with the M46/47. I donít want to go to a ton of trouble to put a worn out transmission that I can't find parts for in my car. I also hate the electric overdrive.


Yeah those Lay Cock things are a horrible joke...dry humor, harumph!

The M47 in my wagon isn't bad...there very well may be parts..Truth is I haven'rt looked too hard..I did ask whassis their names down in Socal---the guys that are real sharp on old stuff..
Hiperauto?? He said as far as he knows things are available..
Like the main 4 bearings, and synchro rings..

That said I have found the best MPG improvement via more torque..
If one POP! moves you this much X distance...and a stronger POP!!! moves you 1.15X distance then to move X on the torque-ier it takes less open throttle..

Only have dozens of V4s and 900s I've built where I'm doing n.a. comp at 10.8 to 11.2....they got better mpg on cross country trips..

Of course that means head off and making chips, but it is the best thing I've seen

(and is a good portion why modern engines get better milage is so many are much higher compression---they get even better if they weren't hauling an average of 1000-1100lbs more than a comparable niche car was 30 years ago..)
The bummer of the problem of high speed cruise is that wind resistance goes up like cube-function

A real example..This car Opel Kadett GSI 1988..Opel XE motor (2,0 with 86 x 86mm bore and stroke) 16v head (from the same place all the Germans go since they can't make a good head--England..) stock 150 hp with cat... pretty good numbers for a 2,0 car in 88
Good clean aero shape

http://techgeist.net/images/opel_kad..._a_rally-4.jpg

According to some fancy German test it took that car in stock for just 7.5hp to go down the road at steady 100 km/hr
But to reach top speed...(214 km/hr or about 132mph) it took all 150hp..

That's one steep curve and it has to be worse for a brick shaped car...

Redwood Chair 06-08-2018 01:34 AM

Quote:

Originally Posted by Lando (Post 5808795)
I have a pedal cluster, clutch cable and cross member from a manual 240 for a manual swap on my 86 245, but I don’t know what trans I want to swap to. I have a bone stock B230F, that I don’t plan on modifying, I just want a manual transmission to improve my highway fuel economy because I know the AW70 is the main contributor to my 24mpg at best. I commute in freeways where the traffic is going 80+ mph.

What is the latest and greatest swap that people are using considering that I don’t need it to tolerate a whole lot of horsepower? I do not want an M46/47. I’d prefer a hydraulic clutch, but I’m not set on that. The T5 isn’t really calling my name either, but the WC variant does have some nice ratios for decent MPG at 80+ mph. I remember readying about some crazies entertaining the idea of a 6 speed Nissan tranny, but had trouble finding the thread.

^ That's not bad at all.

With 3:54's running at 6 or 7 pounds of vacuum I cross the 24mpg line at 67mph @ 2500 rpm.

JohnMc 06-08-2018 08:25 AM

Our beater backpacking road trip back up whatever '03 Jetta TDi got 48 mpg on a road trip through west Texas once, going 80 mph all day long, with the A/C blasting. The worst tankful MPG we've ever gotten from it was 38. In the winter, doing lots of city driving, short trips where sometimes it wouldn't even fully warm up before shutting down again.

Avoid the automatics in those, they don't last forever like the engine does. And apparently, we lucked into finding a somewhat rare car - the 2003 (last year of the older, simpler injection pump ALH engine) in 5 spd wagon form. Does it make a difference that the TDi wagons were made in Germany and not in Mexico? Who knows.

Very useful amount of space in the car, even if it isn't as big as a 4Runner or a 245. And while the car is not fast, it also isn't horribly slow. It's a... very relaxing and competent car to drive. It's just so good at what it does. Admirable in its German efficiency.

vwblue1967 06-08-2018 02:00 PM

My 93 can get 23-24 MPG pretty often with the AW70 and my 85 with the M46 usually get 25-26...now that I replaced my coolant temp sensor, my last tank was 27.2mpg.

I was thinking about swapping in a lockup tans and an L cam just to see what the 93 could do being that it gets a lot of highway miles. Also looking at the time and cost of parts I wonder how many tanks of gas I'd have to run for it to make it financially worth it.

VB242 06-08-2018 02:15 PM

There's 6spd adapters in group buy, but not sure if enough torques to utilize it, you'd have to see how the ratios work with your 3rd member.

283SD 06-08-2018 03:16 PM

Wagons with a standard trans came with a 3.31, rear this should help with your final drive ratio,but you need to change the whole axle housing

lummert 06-08-2018 04:02 PM

AW71L? Lock-up converter will lower the rpm's.

Redwood Chair 06-08-2018 04:36 PM

Quote:

Originally Posted by 283SD (Post 5809190)
Wagons with a standard trans *83+* came with a 3.31, rear this should help with your final drive ratio,but you need to change the whole axle housing

The engineers usually combined the parts bin for maximum efficiency, that in combination with an AT would suck to drive and get worse MPGees.

Kjets On a Plane 06-09-2018 06:02 PM

<s>

Redwood Chair 06-09-2018 10:11 PM

^ :nod:

A Saab will do OK @ 80mph, fuel wise a 240 not so much so.

sbabbs 06-09-2018 10:34 PM

My best was 28mpg at 70 cruise control to seattle in 90 745 with turbo and m46 and 3.54 ratio T cam. Switched to A cam and now it's 25mpg.

DET17 06-10-2018 07:46 AM

Quote:

Originally Posted by Redwood Chair (Post 5809787)
^ :nod:

A Saab will do OK @ 80mph, fuel wise a 240 not so much so.

My first SAAB 900S, NA with 5 speed would hit 32~33 at 70mph.... a little sleeker and better CD than the RWD bricks. My Turbo C900s would never touch that mileage even with the 5 speeds.

Sounds like the low $ solution for the OP is search for a lower mile M47, with the desert gear in back.... skinny tires "well inflated" to reduce rolling resistance.

This thread makes me wonder if anyone with MS conversions to these 4 bangers that upgraded to sequential fuel ever saw better MPG numbers? I can't believe batch fuel is ideal for economy.

MY GOD, we can't be having an efficiency thread in PERFORMANCE, can we? :wtf:

VB242 06-10-2018 10:51 AM

Why does everyone think batch fire is so bad? I think it gives the fuel a little more time to vaporize, but I'm no expert.

John V, outside agitator 06-10-2018 04:08 PM

Quote:

Originally Posted by DET17 (Post 5809908)

MY GOD, we can't be having an efficiency thread in PERFORMANCE, can we? :wtf:

They are 2 sides of the same coin...more efficiency = moar powrz= less fuel consumed per unit of distance..

freevolvos 06-14-2018 08:09 AM

i often thought about the m.p.g. thing myself.. i was wondering if there was a cam that made peak power at say roughly 4k after i put the tach on mine i was shocked to see how little i get above 3 k... In actually started doing it on purpose to get the m.a.f. to self clean.. so what would work advancing the stock cam a few degrees, getting a low rpm cam, shave the head to bring up the c.r. and maybe a tlao chip? i have a 89 engine I'm about to put in and maybe i should get there head done now? a little bowl work maybe?

Dadssleeper 06-14-2018 08:41 AM

One of the main reasons I strayed away from V8's is road trips. I put a 240 together with a B230ft and mated that to an M47 with 3:31 gears. I am running a stock turbo at the moment at max psi of 12. I pulled 28-30 MPG's , I was expecting a little less, but still way better then the 12 mpg's I am use to.


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