best swap for fuel economy?

[highly responsive]

lets imagine that money isnt an issue.

i currently have the SOHC, and i am looking at swap options. one thing that bothers me about the SR swap, is that i will be getting worse fuel economy than what i get now (from what i have googled), and i will need to run premium gas. which swap should i do if i am most concerned with gas mileage? rb, vq, vg, even CA if its a viable option..... even if its one that i didnt mention, please share it!

[1slowS13]

i'd say what you have right now would get good gas mileage if you drive it good, and would cost less, for obvious reasons.

to tell you the truth, the 240sx isnt really the econobox type.

[MADE]

I just dropped 75.00 for 14 gallons and everyone at the gas station was shocked and pissed. "It took you 10 mins to put $75 in the little ass car!" Oh it was great and will last me about a week.


IMO If you worried about fuel economy don't do they swap yet.


350Z's use VQ3.5 300ZX use VG30's I think.

I have a VQ35 powered maxima as a daily and the gas mileage is good.

[downshift_sideways]

hmmmmmmmmmmmmm

[highly responsive]

Originally Posted by downshift_sideways

vq30 38.3 mpg U.S.

thanks, useful info. im sure thats highway mpg, right?
also, do i swap one of those out of a 350z?

[downshift_sideways]

chyeeaaaa boii

[blackrms13]

Originally Posted by highly responsive

thanks, useful info. im sure thats highway mpg, right?
also, do i swap one of those out of a 350z?

Z33 had VQ35...
VQ30 is out of a I30 IIRC

[The ROMAN]

What about an N/A SR? I looked around for mpg figures but couldn't find anything, short of comparing to an SR Sentra. I would assume it'd beat out a KA by quite a bit and they're not too expensive.

BTW fueleconomy.gov lists SOHC KA as 18/24 and DOHC KA as 19/26. SR Sentra is 21/29.

[Z33dori]

just keep the ka...

or buy a honda

[tangch]

One guy that have a vq35 has average of 32mpg. I think their website is nissandoctor.com

[Flybert]

SR's get awesome gas mileage. Stay out of boost and you'll be fine. I remember getting 26-27mpg with a lot of highway. My gas mileage when I had a KA24DE was pretty much the exact same.

[Dutchmalmiss]

I get 26-28mpg(city/highway combined) with my SR and light mods. Owns any other KA mpg from my experience.

[BlckBeautyVTEC]

i get 28 mpg on my KA, but seriously if you want good gas mileage get a civic or corolla

[Camo]

stock ls1 18 city/28 hwy with 345 ponys!!!

[GSXRJJordan]

Yeah I was gonna say LSx also.

The z06, even with a blower/etc (560rwhp) still gets 25mpg+ on the freeway, and around 20mph putzin around town. Keep your foot outta the throttle and away from the high revs.

[Z33dori]

yea most ppl don't realize the less like and idiot you drive the longer you gas will stay in the tank...


really easy concept...

[highly responsive]

thanks for the info on the SR. stay out of boost, makes sense. going into boost would just force more air in, and at the same time increase the fuel being consumed, right?

i already drive like an old man to begin with, and my DD habits wont change with the SR (well maybe not at first :P).

[twistedsymphony]

Originally Posted by Camo

stock ls1 18 city/28 hwy with 345 ponys!!!

LS1s actually get BETTER milage than that in an S chassis because it weighs about 800lbs less.

the people I've talked to that have one average 32-34MPG on a factory spec motor

and yes 340+hp

oh yeah and it weights pretty much the same as a KA...
... and doesn't cost much more than an SR swap

... it really baffles me why more people don't go LS1

[jrocslider]

a friend of mine had a 600hp C5 Z06. after a tune he was averaging about 31mpg @ 70mph hwy

[The ROMAN]

I would still be interested on opinions on an N/A SR and average mpg of people who have them. I'd pick one up for cheap and have a nice DD/small cone-lot drifter. LS6 is what I'm interested in for the next race car build, though.

[twistedsymphony]

don't bother with LS6

LS6 is just an LS1 with bigger cooling lines in the head, different cams and different tuning. Buying a late model LS1 (2000 or newer) will actually have the same heads at the LS6... the LS1 is about half the price of an LS6 and you have to retune the computer to use in the S chassis anyway.

not to mention the LS6 uses a drive by wire on the throttle which is an enormous headache to adapt to a cable system.

As for the NA SR... IIRC it has LESS power than the KA... honestly if you're all about mileage look into changing your rear end gears you'll get more mileage for your $$ there then with an engine swap. the reason the LSx motors get such great mileage has little to do with their design and everything to do with the fact that they make good torque and they're geared well 6th gear on the T-56 transmission is pretty much just for fuel economy and you can bog around at 1200RPMs all the time. I wouldn't be surprised if an NA SR got worse economy than the KA.

[The ROMAN]

Cool, sounds like good advice on the LS6 (haven't done that much research yet). I'm surprised on the N/A SR though. I figured a newer, more advanced and smaller displacement motor would get up in towards the 30s, especially without the emissions bs. Even my turbo SR does pretty well.

[McCoy]

Originally Posted by The ROMAN

I would still be interested on opinions on an N/A SR and average mpg of people who have them. I'd pick one up for cheap and have a nice DD/small cone-lot drifter. LS6 is what I'm interested in for the next race car build, though.

I had the SR20DE, then added a T28 to it after about 6 months.

NA I got about 25/31 mpg (town/hwy). With the T28 added I get about 22/33 mpg (town/hwy).

When I was NA I was using the stock KA exhaust and had no other mods. With the T28 I have added cams, exhaust, and a host of other parts that could play into the gas milage differences. I still get better gas milage with the turbo, except on track, than I did NA.

[gripster]

Thanks to those with NA SRs who shared their experiences.

I'm getting around 27 mpg in my stock SOHC, being easy on the throttle, but I'm still looking into the N/A SR swap as well.

I've also looked at changing the rear end.

With stock open diff (4.xx), I get 3400 rpms at between 70-75 mph.

What kind of rpms should i be at with the J30 LSD diff (3.xx right)? Should be lower, right?

[projectRDM]

Originally Posted by gripster

Thanks to those with NA SRs who shared their experiences.

I'm getting around 27 mpg in my stock SOHC, being easy on the throttle, but I'm still looking into the N/A SR swap as well.

I've also looked at changing the rear end.

With stock open diff (4.xx), I get 3400 rpms at between 70-75 mph.

What kind of rpms should i be at with the J30 LSD diff (3.xx right)? Should be lower, right?

Only the J30t has a different ratio, and IIRC it's 3.92:1, so it's not much of a change from 4.08:1. You could do a 3.55:1 from a Q45 but your car would be a turd in traffic.

[Syncade]

Wouldnt a DE KAT be pretty efficient? Maybe not, but id imagine so.

[KansaiDrifter]

i was gonna mention the LS1 series, but it's been gone over nicely, but the other thing that would boost the crap out of millage would be changing the rear end gears more towards a 3.0 series, the stock 4's are kinda low, plus with the torque/power curve of the ls1 you could easily daily it with something like 3.23:1 or so....

oh and the top speed is yet to be had with one of these setups! 5th gear at rev. limit was 155 mph, with a 6th gear to go, and the 4.0:1 gears, imagine what the 3.0:1 would do haha

[g6civcx]

Originally Posted by twistedsymphony

... and doesn't cost much more than an SR swap

... it really baffles me why more people don't go LS1

I respectfully disagree.

With a complete SR front clip, and assuming the shell is manual, I can do the swap in 1 day. Figure a shop would charge you about 8-10 hours of labour.

With an LSx/T56 front clip, it would take me about 1 month to put together off-the-shelf parts and fabricate everything else. I'm not saying it's not possible. I'm saying the swap kits aren't available yet to where it's plug-and-play. A shop would probably charge you 80-100 hours.


If you add up the cost, the LSx cost much much more. I would estimate 2-3 times more than a regular SR swap, both using stock components when possible.

I've done pretty much the same swap but using an older GenI and T5 to save cost. Everything else is virtually identical to an LSx/T56 swap.


If you disagree, please say why.

[highly responsive]

Originally Posted by twistedsymphony

LS1s actually get BETTER milage than that in an S chassis because it weighs about 800lbs less.

the people I've talked to that have one average 32-34MPG on a factory spec motor

and yes 340+hp

oh yeah and it weights pretty much the same as a KA...
... and doesn't cost much more than an SR swap

... it really baffles me why more people don't go LS1

It might not cost much more than SR swap, but wouldnt you still have to do a bunch of other things to do it properly? Like frame reinforcement, driveshaft, etc?

[Mr.James]

id go SR. the gas mileage is awesome, like previously stated...wonder how the CA is tho? not that i ever cared about gas mileage! and CA would be the least expensive swap as far as i know. or you could get a pack a pitbulls as your reindeer and have a s chassis as your sleigh..