"Warmed up" NA motor MPG estimates?

[HiSPL]

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?

[Dan]

I would expect mpg to go down with a hotter cam..what rear gear would it have?

[culberro]

My NA DD picked up MPGs with 1mm off the head and a B cam.

[Swedbrick]

Mine is around 26-28 with k-cam and 10.3 comp, I'm running wasted spark, which helped a bit as well

[quillc]

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.

[shoestring]

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.

[esmth]

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

[bobxyz]

FWIW you can find the original EPA ratings here: https://www.fueleconomy.gov/feg/bymo...emodelnf.shtml

[shoestring]

And you can peep my Fuelly account here:

http://https://www.fuelly.com/car/vo...samodai/934616

Every fuel up since July 2019 with notes

[dl242gt]

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.

[HiSPL]

Originally Posted by dl242gt

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.

[mikep]

Originally Posted by culberro

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.

[Fred Gwynne]

Originally Posted by bobxyz

FWIW you can find the original EPA ratings here: https://www.fueleconomy.gov/feg/bymo...emodelnf.shtml

My automatic with .040" off the head and a KG Trimning K004 gets about 22 mpg with approximately 80% highway and 20% backroad. Pretty darn close to the number shown in your link.

[HiSPL]

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!

[Harlard]

Donde

[chronicrhythm]

Originally Posted by dl242gt

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?

[HiSPL]

Originally Posted by Harlard

Donde

https://ctbids.com/#!/description/share/732947

Theres 429 dollars worth of buyer’s premium on top of the bid. Total price is 3289.

[GeneralBurrito]

Seeing all these great mileages and here I am happy with ~20 pure city driving :(

[Harlard]

Originally Posted by HiSPL

https://ctbids.com/#!/description/share/732947

Theres 429 dollars worth of buyer’s premium on top of the bid. Total price is 3289.

Daaaang. Good scrore!

Originally Posted by GeneralBurrito

Seeing all these great mileages and here I am happy with ~20 pure city driving :(

Lol try 12-14 city

[GeneralBurrito]

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.

[redblockpowered]

Well bought!

[culberro]

Originally Posted by Harlard

Lol try 12-14 city

Drives 300hp turbo 16v, complains about in-town fuel mileage

[Harlard]

Originally Posted by culberro

Drives 300hp turbo 16v, complains about in-town fuel mileage

Not complaining, just providing some perspective. Don't forget it's a low compression sorta big cam 16v

[shoestring]

Race car gets about 11.5

[dl242gt]

Originally Posted by chronicrhythm

Happen to have a link to that thread?

Sorry, it was a thread on the now defunct brickspeed. The guy was a tuner by trade located in the LA area. He built the 245 so he could tow his time attack Eclipse to the track. He eventually turboed the engine and when that wasn't good enough he 2jz swapped the wagon.