newbie civic owner
 

hello everyone.

i have a 92 civic Si. a little heavier than the CX/VX gas miser counterparts, and much shorter gears.... but a little more daily driver friendly. i'm working on my inital fill up which looks to be around a 45mpg tank. shifting at 3k rpms and cruising at 60mph. we'll see when i fill up next.

my Si has a JDM d15b engine with stock Si tranny and d16z6 ECU. i am going to have the ECU socketed soon, and i will be DIY/wideband tuning with CROME for max efficiency using a combination of JDM d15b and USDM d15b7 fuel/timing maps.

i previously averaged 47.7mpg in my old d16z6 powered CX hatch @ 65mph.

here's my honda-tech garage of past civics:
https://honda-tech.com/garage?cmd=vie...e&id=999307685

see if my signature shows up now

Your signature is up! Good to have you here, doing pretty well with such a little peppy car, :p

Ever considered an HF 5th?

i might consider a DX 5th. that's about as long as i'd go. i'll probably just swap in a DX trans altogether, though

this car is FAR from peppy, in fact... i'd say it's completely gutless. i recently sold an H22 powered EK civic that ran a high 13sec 1/4mile. that was peppy.

Haha, what's wrong with the HF fifth?

Yes, that seems slightly peppy, you could always just get a full-fledged HF, :p

Will EF gears even fit into a EG transmission? What about a VX 5th?

yes, but i believe it depends on the case size. Si/Ex trannies are "big" bearing, VX/Std/DX/CX/HF/etc are all small bearing.

HF/CX/VX 5th are too long for my liking. at highway speeds FE likely goes down because it takes so much extra pedal pressure to overcome aero resistance. that's why i think DX is best. for low speed (under 60mph) they're fine.

It only takes like 10HP To maintain highway speeds. You could always install a 5th gear as a cruising speed (you'd probably cruise around 1500RPM at 70MPH, compared to the 2500 you're probably doing now). if you need to accelerate, that's what 4th gear is for.

Or just do a DX swap. It's still loads better than the SI tranny.

Dang, 47.7mpg while going 65?

I never really go over 60 or so and am in the 36-38 range (90 STD hatch w/ d16z6).

I must suck at FE driving or something.

The EG is MUCH more aerodynamic than the EF, so I'm certain that has something to do with it. I'm certain that other small differences (tire size, LRR-ness of the tires, etc.) account for the rest of the difference.

That seems a bit on the low side, perhaps there is something wrong? o2 sensor maybe?

::EDIT:: just checked it out, that's not bad gas mileage at all.

Welcome. I used to have a 91 STD hatch with a first gen JDM b16, which spun at 4400 @ 80 mph :eek: And I still got 37 mpg in the one highway trip I made, which included two 100mph onramp merges :p Theres a guy on HT who CLAIMS to hit 40 mpg in an h22 hatch, which is "running more rich than Oprah on a treadmill" :confused:

Good luck getting the most FE out of your Honda, but it looks like youve already been doing very well :thumbup:

I also have a B16, and have been getting an average of 35 mpg mixed! Usually keeping the rpm's over 3000

man.... i want to get over 45mpg from my d16z6 swap (without changing driving habits)... how did you do it?

i'm not really sure how. nothing special.

cruise60-65mph on 2 lane back roads
CX chassis
stock z6 ECU
short/warm air intake, OEM z6 header, no cat, stock CX exhaust

47.7mpg is possible. My car got 44mpg at 70mph.
The dx tranny is just right. I would want a taller 1st. My 1st is too short, I don't know how the ex and si guys are handling it.

that was my setup for a year but the best i could get back then was 36mpg. then again i was never going even 65..... i did notice a .5mpg drop after putting a cat on...

You have different cars, and you don't have a vtec engine like 90CivicStandard has.

A DX engine is built for Fuel Economy much more so that a d16z6 engine is.

i handle it all the way to 35mph daily. i dont know what youve driven in the past but civics do not have a short 1st gear.

For me it feels short. My altima's 1st gear went up to 44mph with it's misely 6100rpm redline.

The civic has 6800rpm redline and 39mph max for 1st. It's short.

we have different cars but I do get that 47mpg at 65mph.
Get 52mpg at 55mph
60mpg at 32mph
65mpg at 35mph.

its not short, its short relative to your old slow off the line altima. but not relative to any other honda. they dont even make any b series 5spd trannies that are that long.