L36 Mods and MPG

[Madcarpenter]

A few questions for those of you who have installed the most popular performance mods for L36:

* How do these relatively simple mods affect your fuel efficiency: Magnaflow Cat, FWI, Flowmaster Muffler?

* How about the more involved/expensive mods: PLIM, PCM tune/aftermarket PCM, Yella Terra 1.8 Rockers?

Specifically, I'm curious to know what happened to your MPG's after these mods. Would also appreciate suggestions to otherwise mod for more MPG's.

Thanks for your replies, and sorry if this has already been beaten to death, but I didn't turn up many answers with the 'Search' function.

[01bonneSC]

You will see a gain with fwi, hi flo, mufflers don't make a diff.


It's all about keeping your foot out of it, no matter what mods you have. Truly and honestly its about being easy on the gas. Anything short of a cam isn't going to make it worse.

[00Beast]

The muffler won't affect mileage or performance at all, it's merely a sound modification on these cars.

The FWI and a DP or even just a HF cat will improve mileage and efficiency, provided you don't utilize too much of the extra power you get out of them.

The same applies to the other mods, but the law of diminishing marginal gains appears here.

[95naSTA]

ZZP ER ratio rockers will out perform 1.8 and 1.9 ratio rockers on a L36. They are the optimum ratio which was found through R&D.

My GT1 cammed/Ported head & LIM/TOG header/HVII/L67 TB L36 with terrible compression (~130ish) was able to get 25 mpg highway with 2.97 gears.

[Madcarpenter]

'The Law of Diminishing Returns' ,yess! I usually invoke that when I'm trying to get that nearly perfect coat of drywall mud a LITTLE bit smoother, and then make a mess of it by running the taping knife across it just ONE more time...

Thanks.

[deano55]

LOL

[nos4blood70]

My average for basically 95% city driving went from 18.7 to 19.3-19.5 after my FWI.

[Phantom]

One of the bigest changes that you can make is tuning the PCM but a lot if it is adjusting the shift dettings and TCC locking speeds. That will make the most difference if you do more low speed driving, if you get on the highway right away it will not make much difference. For hw driving increasing the timing in cruise can help MPG.

The easiest way to increase your MPG is to adjust your driving style, keep the throttle under 15% on the highways as much as you can.