valve size VS. MPG

[drewzx3]

Is there much difference in mpg when you run like a 2.02 valve compated to a 1.90 valve? Like comparing the edelbrock performer heads with the 1.90 valve instead of the 2.02 is it going to make a bit of a difference?

 

[cbarr300]

I've seen several instances where putting some "go-fast" parts on an engine can actually increase the MPG.

If you can make the engine more efficient....then you will see better gas mileage so long as you don't floor it all the time.

Whether or not you see a big difference is all up to part selection.

I'd think that all things being equal...if you changed out just the valves....you wouldn't see that big of a change.

just my .02

 

[final5-0]

Lets get specific here

Mechanical First

We are talking about a Stang with .......
all the hot rod parts in place like heads, cam, intake, etc
all supporting parts in place and functioning properly
no issues such as vacuum leaks and the like

Simply Put ... Typical NA Street Combo

Driving Conditions Next

Cruise down the highway
and
Not ... driving around town

To many variables in around town driving :Word:
Mostly ... a heavy right foot

Tune Last

If you got all your hot rod parts installed perfectly and all other things
in good shape but you are still running on the unmodified pcm

Your tune is gonna be off a good bit

You just can't expect to be making around 300 rwhp without flowing
MUCH MORE air and fuel

The pcm has no way of knowing this
and
No longer is it as efficient as it once was
When things were stock at obtaining the most power
for
The least amount of fuel used

Here is the deal about a Custom Tune many don't consider

You change the values in the pcm to reflect what needs to be changed
due to the addition of all those hot rod parts.

Sure ... everybody can see you do that to make more power

BUT ALSO ...

You do the Custom Tune Thing to bring back in line the pcm's ability to
use its Closed Loop programming to make the best use of fuel at any
given moment in time when you cruise (non wot) around town.

Bottom line is ... WAY MORE ... to Tuning than just ... WOT :Word:

I've gotten over 19 mpg at a cruise of 75 mph avg on short trips
so
Its no stretch of the imagination to expect more at the speed limit

Now Summing Up

Does it make sense the valve size would have no bearing on fuel use
during a cruise as the pcm can find the optimum use of fuel

Grady

 

[Darrin]

I was just about to say that....