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Discussion Starter · #1 ·
What have you guys found that definitely affects mileage?.....beides keeping your foot out of it:D

Compression?
Timing?
Engine temperature?
Quench dimension?
Iron heads?
Alumnum heads?

What relationships have you found that make a difference?

I'm thinking (but want to know) for a mild, almost stock small block, the best mileage combination may be:
9.5/1 compression
195 degrees
040-045 quench
Aluminum heads 64 cc heads (swirl shaped chamber)
Timing curve flatter than the usual performance curve
 

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DC Crew
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Just to chime in .... don't forget about weight, gearing, rolling resistance/friction of the tires.. aerodynamics... but we'll assume that aerodynamics is something you cannot change.

I think the reason the C4 gets such excellent highway mileage is because of the 6th gear and the extremely low RPM at highway speeds.

What RPM are you at during highway driving? Just curious.
 

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Fuel Injection vs. Carb is a big one in my book.

From personal expierince...

My mileage dropped after a tranny rebuild. I assume its because everything was tighted up, and the engine had to work harder to transfer its power.

Also, the elimination of a clutch fan is a benifit to mpg, as the engine has less mass to spin.
 

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I need to say the aerodynamics plays a big part in the C3, in my 77 driving on the open high way with windows down, or T-tops off, I experience 2-3 mile per gallon drop.
 

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Discussion Starter · #5 ·
2000 rpm = 50 mph
2500 rpm = 62 mph
3000 rpm = 70 mph

I agree with all points made above.

My old oil burning engine made from 18 to 22 mpg on the highway.

Last years new crate engine is basicilly the same block and cam with these differences.

My carb and intake manifold and headers are the same.

the difference is old 18-22, new 14-16 mpg

old assembly had 015 head gaskets---new has 041(quench)
old was using 195 t-stat---new one using 180 (combustion heat)
old distributor curve was flatter (negative torque?)

So far, the change from clutch fan to alum rad and electric fans has made no mpg difference.

Not that it's a life breaker, but getting good mileage is a passion of mine. I believe that engine efficiency and performance go together. Also, I've always thought that on the highway a carbed car should get the same mpg as a FI car, gearing being factored in.

An OD tranny has been on the plan list for a long time. I just haven't decided on whether to stay automatic or install a manual 5 or 6 speed.
 

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Discussion Starter · #7 ·
Re: Gas mileage?

evilsmf said:
Miles pre gallon or gallon per mile? :partyon:
Damn:surprised
 

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DC PIT CREW BOSS
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The hell with mileage. If you want good mileage, get a Honda
 

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Discussion Starter · #9 ·
Torch Red 2K said:
The hell with mileage. If you want good mileage, get a Honda
Oh c'mon:huh: It's about efficiency. :) :cheers:
 

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biltogo said:
2000 rpm = 50 mph
2500 rpm = 62 mph
3000 rpm = 70 mph

An OD tranny has been on the plan list for a long time. I just haven't decided on whether to stay automatic or install a manual 5 or 6 speed.
Yep gearing is a big factor. My 88 at 2,000 rpm is at 74 mph. Gotta make a big difference.
 

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Re: Gas mileage?

evilsmf said:
Miles pre gallon or gallon per mile? :partyon:
evilsmf. Nice car but where is the blower belt. I see the blower pulley but no belt, no side pipes. I would love to post a picture of my car but being new don't know how?
I have a 8-71 blown big block.
 

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Re: Re: Gas mileage?

norvalwilhel said:
evilsmf. Nice car but where is the blower belt. I see the blower pulley but no belt, no side pipes. I would love to post a picture of my car but being new don't know how?
I have a 8-71 blown big block.

to post a pic first it need's to be on the web ie. http://www...
Try http://www.freepichosting.com if you dont have a web page There you can up load your picks and then get the URL and paste it between
and boom you got your pics...:thumbsup:
 

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Screw the honda..get a yugo....right pat?

:)
 

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Just joking bro...have fun! WOOT!
 

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my original/stock '82 gets 23+ MPG @ 75+ MPH, A/C on, T-tops off, often over-riding the cruise-control. Hope to make 600-mile, mostly Interstate trip this July; will update at that time!
 

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Re: Re: Re: Gas mileage?

evilsmf said:
to post a pic first it need's to be on the web ie. http://www...
Try http://www.freepichosting.com if you dont have a web page There you can up load your picks and then get the URL and paste it between
and boom you got your pics...:thumbsup:
Just testing to see if my pictures can be transferred from Corvette forum.
This is my motor in my 75 vet
 
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