LS1/LS6 Fuel Mileage

[kce]

For those of you with an LS1/LS6 swap into your Datsun I'm curious to hear what kind of fuel mileage you are getting. Obviously, if you have an V8 swap fuel mileage probably isn't your top priority (it isn't mine either) but I imagine it's nice to have a daily driver that doesn't need a fuel tanker as a support truck (particularly in this economy).

 

I've heard some pretty crazy claims come down from 4th-gen Camaro owners about getting anywhere between 27mpg to 32mpg (*cough BS!) in sixth gear with mostly light-foot highway driving. The S30 is probably significantly lighter... I wonder if they're getting similar or better numbers.

 

If you can, please post relevant information about your induction system, exhaust and any other internal modifications you've made to the engine. I'm particularly interested in comparing the numbers between fuel injection and carburetion. Also your transmission and differential gearing if you know it.

 

Thanks!

[Cable]

 

I've heard some pretty crazy claims come down from 4th-gen Camaro owners about getting anywhere between 27mpg to 32mpg (*cough BS!) in sixth gear with mostly light-foot highway driving.

 

Its possible with the cars that have DoD (displacement on demand). I owned a 2007 HEMI Charger (with DoD) that would get 27 mpg on my way to and from Vegas. Of course I had the cruise set, good gas in the tank, and behaved like a good boy and did the speed limit (mostly 55mph).

 

But to answer your question, my Z usually gets 20+ in the city and usually gets 28 mph on the freeway doing 80+ mph, but if I stay in the 65-70 mph range I've got as good as 32 mph.

 

I'm particularly interested in comparing the numbers between fuel injection and carburetion.

 

Thanks!

 

In short, there is none. Hands down EFI is better for mpg.

 

Example: If you have two identically built LS motors, one with the factory EFI (and tuned correctly) and the other with a carb setup (also tuned correctly), the EFI will make the same power (if not more), have better street manners, get better mpg, and the EFI motor overall will live longer.

[kj280z]

I am getting close to finishing my ls1 conversion and would love to get 30+ mpg as some have stated they are getting. I will certainly share my findings as things progress further

[kce]

Example: If you have two identically built LS motors, one with the factory EFI (and tuned correctly) and the other with a carb setup (also tuned correctly), the EFI will make the same power (if not more), have better street manners, get better mpg, and the EFI motor overall will live longer.

 

Sure, that makes sense. My big objection to fuel injection is 1) the cost of the retrofit and 2) difficulty in tuning. Now I realize the second objection is relative but I'm pretty much a carburettor guy and most of my experience is there. But 30mpg is music to my ears. I'll have to reconsider my induction prejudices.

[janaka]

I'm probably in the teens for milage 13-19 mixed.

That said I have 3500miles on the swap in the two yrs its been on the road. So for me either the clutch is in or the right foot is down. I'm sure on the hwy I can get mid-high 20's if cruising in 6th gear if I tried...big if there because 4th gear on the hwy is just a TON of fun.

 

mods

224/224 cam

FAST 90mm intake and TB

1 3/4" headers

3" sinbgle exhuast

Edited June 14, 2010 by janaka

[Cable]

Sure, that makes sense. My big objection to fuel injection is 1) the cost of the retrofit and 2) difficulty in tuning. Now I realize the second objection is relative but I'm pretty much a carburettor guy and most of my experience is there. But 30mpg is music to my ears. I'll have to reconsider my induction prejudices.

 

This is most peoples objection(s) to running the LSx w/EFI.

 

However if you bought a turn-key motor with the harness, PCM, etc its actually cheaper than going with a carb setup on a LSx. How you ask? Well the Edelbrock LS1 manifold kits sell for $650+. They include the manifold, ignition box, and the harness needed. Although you still have to run a MAP sensor, factory crank sensor, and factory cam sensor for everything to work. Not to mention buy a carb if you don't already own one (more $$$).

 

Wait 4 Me Performance does all my harness/PCM work on all my personal and customer LSx swaps. Its $360.00 to convert a truck harness and PCM for stand-alone operation, plus free re-tunes and adjustments for LIFE.

 

Unlike a carb that needs adjustments here and there, plus carb rebuilds from time to time, a LSx PCM is tuned it once and forget it (unless other changes are made) and is generally maintenance free.

[Guest NESS89]

I get around 27mpg freeway doing 80 in sixth gear with my swap. All stock tuned LS3, t56 and 3.70 gears in my rear end. I think its pretty good since my 99 civic used to get 30 on the highway.

[kce]

Currently I'm reading through Chris Werner's How to Rebuild GM LS-Series Engines and I'm finding it useful. I really like the idea of a 400hp engine that can get close to 30mpg if I drive nice and have overdrive. You just can't get close to that kind of "have your cake and eat it too" situation with a carbed small block chevy.

 

Anyone with a Gen IV retaining the Active Fuel Management (displacement on demand) stuff? If so, how difficult was adapting it to the S30?

 

Thanks for all the great info.

[SSflyer]

I'm one of those crazy Camaro guys who claim 30+mpg on the freeway. My 99 SS with LS6 heads & cam got over 35mpg one time between Phoenix and Yuma. An elevation drop from 1800ft to sea level over 135 miles going about 60 miles an hour. My Z with a 2002 LS1 with a HotCam and longtubes gets 15-17 in town and 26 on the freeway. I had hoped for over 30, but 26 ain't bad.

[SUNNY Z]

Yep, another 4th gen crazy here. My stock 01 SS ROUTINELY got 27, with a best of 32 mpg. 6 speed, naturally.

[kce]

That's nuts. My Toyota 4x4 has a 3.0L and gets like 18mpg. I am officially jealous. Needless to say, I do alot of walking.

[ColtGT4g63]

When I had the 6 spd in my 240Z, best I ever did with freeway only driving was about 30mpg. Now with the TH350, high stall converter, turbo, and biggie injectors I get about 9mpg. Maybe 12 on the freeway..