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"Warmed up" NA motor MPG estimates?

HiSPL

Fanking Champion 1993
Joined
Jan 8, 2015
Location
College Station, TX
I'm jonesing hard for an 88 M47 car. Auction ends tomorrow.

I would leave this car mostly as-is and daily it. If I skimmed the head and added a K or an H cam, adjustable cam gear, and hotter ignition, what do you think the MPG would be?

This would be a 90 mile a day car for me. Not interested in tons of power, but would like it to cruise at 80+ and not feel like a slug. Just wondering if you think mpg would go up or down?
 
83 B23 high compression motor (shy of 11:1) running an H cam, Nuke gear, Stahl header, 2.5" exhaust, 24# injectors, MSD 6A. M46 trans. 24 MPG consistently.
 
I'm cut 1mm for 9.8:1 with a V cam, M47. 20 mile one way commute to work, 10 highway and 10 suburban. MPG just over 23 in the winter, about 26 summer. Winter highway economy is never great, maybe 25-26, but summer is 28+, best of 30.7. I'm on LH2.4. Highway speeds about 75.
 
B cam straight up on an otherwise untouched long block and 3.73 rear got me 23.8 winter mpg over the last 1200 miles. Mostly 35-55mph backroad 1 lane highways. Hoping for more once it warms up and new skimmed head goes on ;-)
 
My friend used to consistently get 30mpg with his 88 244 m47 car. My old 86 used to get 30mpg with an m46. Those are highway miles. My present wagon gets about 25-26 in mixed driving.

With regard to making mileage. From what I remember on an old thread on another board. The car maker leaves some mileage tuning on the table and with a stand alone you can run the engine a bit leaner than the manufacturer does. The guy in that old thread claimed he got 36mpg and 110whp with a stock engine. It was running sequential injection which probably helped a bit.
 
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My friend used to consistently get 30mpg with his 88 244 m47 car. My old 86 used to get 30mpg with an m46. Those are highway miles. My present wagon gets about 25-26 in mixed driving.

With regard to making mileage. From what I remember on an old thread on another board. The car maker leaves some mileage tuning on the table and with a stand alone you can run the engine a bit leaner than the manufacturer does. The guy in that old thread claimed he got 36mpg and 110whp with a stock engine. It was running sequential injection which probably helped a bit.

A standalone with a "lean tune" is the biggest thing you can do for efficiency concerns. My Honda Insight (RIP) ran about 25:1 afr's when off the throttle or just maintaining speed. That does crazy good things for MPG. It would drop down to 14:1 as soon as you put any load on the motor.
 
My NA DD picked up MPGs with 1mm off the head and a B cam.
When I went from an 88 B230 with M cam to a B23 (flat tops), it got better mileage. A cam was maybe a little better than B, but it was not a scientific test. Woodenpudden might remember better. I think 28mpg was normal.
 
I

Won

The

Auction



I am so pumped right now! Its more money than I’ve ever spent on a Volvo but I think it will be worth it. This car is cherry!
 
My friend used to consistently get 30mpg with his 88 244 m47 car. My old 86 used to get 30mpg with an m46. Those are highway miles. My present wagon gets about 25-26 in mixed driving.

With regard to making mileage. From what I remember on an old thread on another board. The car maker leaves some mileage tuning on the table and with a stand alone you can run the engine a bit leaner than the manufacturer does. The guy in that old thread claimed he got 36mpg and 110whp with a stock engine. It was running sequential injection which probably helped a bit.

Happen to have a link to that thread?
 
I get like 18-20 depending on temperature. Only things I've done were cut springs, swapped to B cam, and swapped to bigger exhaust piping from a turbo model.
 
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