Turbo D16

i have been playing with vtec-e's for some time now and i cant get the best mileage that they claim that it does

ph16 or philippine version of d16y5 on a 4 door ek gets roughly 25mpg(maybe its the o2 sensor that they never came with nor the egr valve). years back i put a t3/t04e turbo and ran uber on p07, then i started playing with the fuel consumption.

idle = 16.5, 15.5afr w the a/c on and 18 deg.
lean cruise = 100kmh, 2800rpm, 12inhg, 16.5:1 afr and 36 deg btdc.
full throttle = 15 afr low vtec
9psi = 12afr, 28 deg btdc on stock block

th engine lasted 2 years and eventually broke the ringlands. but i nver went pass 30 mpg.

i replaced it with d16a from japan and it is also has vtec-e vavletrain

from idle(19inhg) to 10inhg = 20:1 afr, plays around 18 deg btdc
lean cruise = 100kmh, 2800rpm, 8 inhg, 19:1 afr 18 btdc
full throttle = 17 afr, low vtec
16 psi = 12.5 afr, 12 btdc on stock block again hehehe. i get wheel spin on 2nd and torque steer on 3rd, dont know how long its going to last:)

i get 25 mpg with 20 -18 afr. i run lower timing now since i took notice that i get swirl on the combustion and lean mixture so the flame propagates faster across the chamber. i also noticed that i get better mileage if i lower my vac by 12 inhg which in turn adjusting the afr to 16.5 to 17:1 and 30 deg btdc. the highest i got was 32 mpg.
i had set the timing for cruising at 18 btdc but that only lowered the vaccum.

anybody please say what you can, im all ears

stock d15z1 (us 92-95 civic vx)
50mpg at 55mph all highway
45mpg at 65mph all highway
38mpg at 75mph all highway

i think the y5 is rated for 42-45mpg
i think you are running it too lean
the lean a/f's are strictly for certain conditions...like highway cruise...
driving style effect mpg more than anything
i'm part throttle 99% of the time and rev to 2500rpm
getting on the highway i sometimes rev out 2nd gear to cruise speed into 5th

also your transmission final drive will effect the mileage if its not the stock y5

i wonder what kind of an o2 sensor does the vx has. im using a plx wideband and leanest i can get it to is 20:1, leaner than that i get len a/f on the gauge. the 5 volt mark on the o2 calibration is at 20:1.
i hear vx or vtec-e's run super lean at 22:1, if theyre running bosch L1H1 how can they read beyond 20:1?

maybe its the egr valve thats making all the difference huh? what do you think?
the egr valve on the d16a japan has its egr on the runners on the intake manifold because most egr valves i know of is located before the throttle plate. and i dont know if the two terminals on the egr is for switch/sensor or a coil to control the vavle since it has a manual idle control vavle that looks very weird

JDM D15B

16:1 AFR cruise maps; no lower than 14.7:1 when lightly accelerating; and heavy acceleration got ~13.5:1.

I was logging a steady ~44MPG to and from San Diego from the bay area. AVG of 90MPH on 5, accelerating between 75 and 105 on the regular. I could make it all the way to compton to fill up, then go all the way to Aguanga (near diego/Temecula) and back to the top of the grapevine and still have ~2 gallons to spare. I could make it the rest of the way home no sweat on that last bit of fuel.

I honestly don;t know how I got that good of mileage doing 90+... but it was there, and I just need to dig up the receipts and mileage figures to find out.

I used to make 200+ mile 1-way stretches to Sacramento on the regular too; avg'd 38 MPG; I would always make it to Sac on less than 1/2 a tank. I had no clue what my AFR was then... sorry!

I think the VTEC-E ecu's impliment some sort of a timer and routine for controlling the lean burn mode; and I do know that the VTEC-E is active below 2,500 RPM, so this is a big part of the usefullness of it; what tranny are you running?

by the way i live in the philippines

i get to share a 2 lane road w goats and cattle on the side and crazy jeepney drivers hogging the roads.
my average speed is 20mph. it takes me about an hour to drive 30 km

they say its a 4.1:1

at 2800rpm im at 100km(62mph)

yeah its wierd when i looked at the p07 bin, the fuel values are higher compared to other map like the p30 or p28. i cant guess if the y5 is running 190cc injectors

My roomate has a beater d16a(same as a z6 i believe) in an eg coupe that we tuned for fuel economy in a similar fashion. I took it on a long trip once and got about 41mpg with me beating on it a few times for the heck of it. He has noticed up to 44mpg before as well .

Are you Crazy?

12.5 Air Fuel Ratio? at 16psi? maybe.. 10.5-11 would be a WAY better Idea.

and.. 9psi.. 12 AFR is okay.. But.. Full throttle N/A Should be low 13's High 12's for AFR. You're Nuts man.. You're going to melt valves and pistons....

and he has a short final drive
2800 rpm at 63mph is an si/ex tranny in 5th gear with 185/75/14" tires
4.25 final drive

not a good gas mileage tranny

oh and in case you are missing mine and others previous comments

YOU ARE RUNNING TOO LEAN !!!

anything leaner than 16.5:1 is detramental to mileage if not under the right conditions. cause it takes more foot to make the same sustaining power.

and adds heat

im running 2650rpm(according to vafc) @62mhp on 195/50/16 sorry

thas right! 12.5 afr 16 psi! before it was 13..hehehe doesnt mean that everybody is doing 10.5 means its the only way to go right? i know 10.5 works i just want to try different things.
i broke my first engine because i sat my valves using a drill and a piece of hose to make it faster. then 1,2,3 cyl leaked and no 4 cyl rod bearing shitted itself with the crank but thats before i broke all the ringlands since the total timing was 28btdc @ 9psi on a stock block .....sometimes 16 psi hehe. that engine ran for 2 years!

i think we break our ringlands through incorrect timing. even n/a guys break ringlands the more i ask the more it leans toward timing

before i was reading 850 deg f after the turbine with 16.5 afr. now with super lean cruise i get 780 deg f.. timing plays a lot with heat

i understand what yall r saying with what 16.5 is the best and all... but i still dont understand why they say of 20+:1 afr on vtec-e, honda fitz or jazz... is that just shit that comes out when they want to sell?

If you're monitering the EGT's... Then you should mention that... I know timing plays a HUGE roll in EGT's... You should see them skyrocket when you use an anti-lag system..

12.5 afrs in boost isn't really crazy.You will make the most power around 12.5.1 The reason more people don't really tune full boost that high besides race cars is because you might want a safety margin and thats a good thing for a street car. If something goes wrong at 12.5 or for some reason something throws your tune off your going to be screwed if you go past 13.0

10.5 is super rich.Personally I start at 12.5 till about 5 or 6 psi and work down to 11.5 on 1 bar.When I tune for 20 psi Im going to go down to about 11.0 but I could stay at 11.5.1,I just want that saftey margin.


A good read on afrs and about being too rich in boost
http://www.innovatemotorsports.com/resources/rich.php

I know nothing about vtec-e so I can't comment on anything else besides that,but 17 afr at wot and 20:1 sounds crazy lol


edit
I did find this on the ectune forums just now and someone datalogged a stock vtec-e motor
http://forum.ectune.com/viewtopic.php?t=626&start=0

22afr with vtec-e activated cruising.My wideband won't even read that high. At wot its about 12.8-13.0.Part throttle is 14.7

^^^ yes but thats with the d15z1 head...
MUCH different motor than the d16y5...
for one its 1.5L instead of 1.6L
the throttlebody alone on the z1 is 42-43mm...and the combustion chamber is 25.3cc
the d16y5 has a 56mm tb and the head chamber is 32.8cc
completely different pistons and rod/stroke ratio...

you simply cannot compare them

low profile tires drop your engine rpms at a given speed
because of this your cluster reads 62mph...but you are actually going 65...
you may have a dx tranny (4.058 final drive)
a 4.door ek stock would have 185/75/14's
and thats what i'm basing it on...
so i really need the original tire size for your car to judge this correctly

thats why i said I know nothing about vtec-e

I just thought it was intresting it actually goes that lean.

So basicly.. When cruising.. in VTEC-E, is the only time when your AFR Should be so Lean.. Otherwise.. Everything else.. Is 'Normal'... AKA.. Don't run Part Throttle, or WOT in a lean condition... Only Cruising

I think in lean burn city driving it will show up to 16:1... but haven't owned one so can't say.

yea they say its 4.1:1 tranny

ill try the 16 afr next time. yes i have egt sorry again. the antilag only heats the sensor not the combustion chamber plus theres less pressure in the manifold so its not as hot as we think it is

on the lean cruise if we go with 20:1, it lowers the vacum to 8inhg from 12inhg on 15-16 afr. now my point is theres more air to burn if the vacuum is low, hence more fuel to compensate just to stay in the powerband it needs to keep the car cruising against drag.

i know BSFC is linear only if a control is used such as 14.7:1 if we change that then itd be different set of rules.

im going to try.. say 20:1 afr again on lean cruise.. im thinking about the timing again.. ihad it 36btdc(lean cruise) before and i couldnt hear any ping but the ringlands gave up...anybody?