My G35 Gas Milage is ususlly about 16-17 mpg.
On a tank, 17G fill, I get 270-290 miles on highway commute.

After install 10 Wire Ground. I got 320 miles with 17 G.
That's 19 mpg. I was very happy, but not for long.

A few days later, I installed the ME 1/2" plenum Spacer.
I saw my mpg going back down to about 16mpg, about 270 miles for 17G fill.

Same commute & same route & same driving style.

WTF? I didn't really get any faster, as I have a G-timer & I do a 1/4 mile run at the same place onece in a while before & after the install. It actually lost 0.2" right after ME spacer install. With the ME spacer, I am paying $10 more for a tank of Gas with no noticable performance inprovments.

Anybody see similar happening???

I am thinking about taking the plenum spacer off. Anybody interested?


thanks

 

How much to 92626.

 

From what I have been hearing (and seeing on dynos) the '05s aren’t seeing the kind of gains from the spacer that 04 and earlier are... I have the 1/2" spacer and it is one of the top mods I done! Butt dyno, and actual dyno leave me extremely satisfied!

As for mpg... mine hasn’t gone down, even though I drive "spirited" much of the time!

I’m not saying it’s no good for ’05 (cause I don’t have one) but it apparently didn’t leave you warm and fuzzy like mine did. For '03 & '04 owners, it's a must IMO!

 

I thought it was just the '05 MT

 

^ This was my understanding as well.

 

Someone can correct me if I'm wrong (and I very well me be) - but the changes to ‘05 affecting spacer gains (or lack of them) are the same on manual and auto. They have the same motor, so I don’t know why it would be any different unless the ECM is programmed different and even then, I’m not sure how much if any that would change the spacer gains.

Like I said, I don't have an '05 so I'm not the best person to comment. My previous post was to say for '04 and previous it definitely is a must mod!

Someone else with more expertise on '05 can chime in as to whether it's worth it for those cars.

 

I saw with my own eyes the losses on the 05 with the spacer. You lose about 7-9hp to the wheels. But its all top end power gain with that mod. I have an 03.5 and I gained about 18-22hp to the rear wheels. This all being on a Dynopack. And remember your putting more air in which means you have to have more fuel so if you mod dont complain about your gas milage. Not trying to flame on you bro but come on you cant have the best of both worlds.

 

Only the 05 6MT had the redesigned plenum that precluded gains from the MD spacer.

Also, you want to go through several tanks of gas before making conclusions about a mod helping or not helping gas mileage. The one fill up where you go 19 mpg might have been a fluke?

Now if you take the spacer off and you go back up to 19 consistently, then that would be more meaningful - let us know if can...

 

Well said and good advice.

 

Let me drive a few more days. If no change, I might take if off & see
if I could go back to 19mpg. I'll G-timer it before & after as well.
I am not ready to make conclusions yet, just want to see what experences are out there.

I wouldn't mind the MPG go down if I see gain, but my G-Timer sees no gains, just burn more gas. Also, I think G-timer is better than Butt Dyno. I could not tell the difference of 0.2 second on 1/4 mile by butt dyno. I took my G-timer to the drag & get it calibrated. It's within 0.2 second of the Xmas Tree Time at drag consistantly in the same direction, not bad.

I got the spacer because Tony said the lack of Gain is only with 05 6MT,
the 05 5AT should be the same as 04.

Any other 05 5AT with spacers out there? I wonder if there still be a differnce between 5AT of 04 vs. 05, becaues one rated 260 & the other rated 280. Maybe the room for improvment by plenum spacers is gone
becaues of that?

 

Atsmospherics or slight changes in mounting could account for the g-timer differences. Any change in induction sound that might point to a small gasket leak? Did you re-use the OEM gasket or utilize a new one?

The gains I've seen on '05 non-rev up motors fall in the 6-10 hp range, which is a little bit less than the '03-'04 gains (up to 15 hp!)

 

A follow-up to this.

My last tank was 291miles with 16.84G fill-up. about 17.3 MPG.
Getting a little better.

I agree that some how it may take a while for the car to get used to the change.

 

I'm not sure about what refineries are doing these days, but isn't this about the time of year that they usually start putting out the reformulated gas? It could have an effect.

Anyone know for sure?

 

Correction: The motor for the '05 5at and 6mt are different. The 5at has the same plenum as the 03-04's... the 6mt is the "rev-up" version with a new plenum design. The 05 5at should experience the same gains as the 03/04's. For those looking for a plenum spacer for their 05 6mt's should look into motordyne's new MREV design for the rev-up motor. I will be installing a motordyne 5/16" and iso-thermal within the next month and i'll let you guys know my thoughts.

 

This is very interesting stuff because I am thinking of installing spacers on my 2005 G35x. Maybe I should just get the crawford plenum. What do you guys think?