Ok starting out, i picked up this motor a few months ago and picked up a DX shell, doing 200+miles a day i need a good high mpg commuter, my b16 with the realy short S1 finaly drive is killing me on gas, so now you know what my application is for and i need help regarding and pertaining to my MPG factor, i need replacement for some of these parts and i need help but i do NOT need it in the speed/faster performance aspect, instead i need to milk out as many mpg as i can. Thank you.

so starting out, Is the MPFI-HF swap equivalent to the MPFI-Si swap? i couldn't find any specific DX->HF swap's, i was told the Si's is the closest and i should follow that path.

The exhaust maniold!, the catalytic converter is this BIG piece of metal , do i NEED this SPECIFIC type of catalytic converter for my high MPG request? or any ebay 4-2-1 header would suffice and do the job? i can't seem to find any pictures so here's the what i'm talking about:

the cat is cut out in this, but you can kinda see how BIG that thing is (marked in red)? why is it like this? and do i need it for my optimal-high-mpg performance?


This i can't seem to match up in the service manual either, apparently the coolant-water runs through this, and its got this plug sticking out of it, this wasn't on my Si or the DX, once again do i NEED this for my high MPG performance? and if so WHERE how do i wire it up , there's no mention of it in the MPFI swap
here's the picture:


Tranny question :
I got the flywheel with this HF motor, but NO clutch, i read somewhere that the clutch+flywheel should be more or less from the same year and prefereably from the same model(dx,si..and all) and i have 2 Si flywheels and 1 good clutch, does the HF flywheel weight Less then the Si flywheel? and is that for the MPG factor again? if not can i use my Si flywheel with my Si clutch on an HF motor?

one LAST question, when i was replacing the timing belt my buddy happen to play with the cam gear and he moved it just with his hand like a mere few degrees, and now i don't know EXACTLY where the cam gear was when i took the timing belt off! would just moving it by one hand just a little mess up the timing between the cam's and the pistons? like he ONLY moved it JUST a few degress till it hits the valves i guess and there's just that few degrees of play without the timing belt, would that mess up my timing?


thanks for taking time in this thread and any help is greatly appreciated!


Modified by pr3d at 6:20 PM 7/7/2006

 

last picture looks like the egr? i dont know...might be called something els. i think some cars had that ugly cat right there but im sure you can get a different manifold and put the cat right after the down tube.

 

Last one is egr, you want it,

I'd just leave the cat the way it is, the exhaust system was designed in such a way as to aid the car in heating up quickly and efficiently.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SVOboy &raquo;</TD></TR><TR><TD CLASS="quote">Last one is egr, you want it,

I'd just leave the cat the way it is, the exhaust system was designed in such a way as to aid the car in heating up quickly and efficiently. </TD></TR></TABLE>

ok so the EGR is needed, how would i wire that to the DX chassis? or is it any different then the Si swap?

so i can just use some shitty ebay header, if i'm not entirely worried about car heating up quickly, but would it be indirectly used as a source of hotter air, since hotter air doesn't combust as aggresively and less energy is needed or exerted, in turn helping the gas mileage just that little bi?

edit: i got the manifold but i didn't get the CAT converter, so i need to either place the whole exaust manifold to a new cat, OR try to find the OEM HF cat. i feel that replacing the stock exhaust would be easier then finding that OEM cat.

 

the engine wiring for the HF is the same as the Si, except for the EGR Valve, which is the thing in the second picture - it is mainly for emissions and shouldn't affect mileage much if you leave it disconnected, however, if you are running the HF ECU, you will get a code for EGR - the close coupled cat is mainly for weight savings and shouldn't affect mileage if you ran one from DX or Si - you probably won't get quite the mileage as you would in the actual HF since you have a heavier car and the HF has other sensors that the ECU reads to change the amount of fuel being supplied - things like switch on the clutch pedal to tell ECU when clutch is depressed, switch on back-up lights to tell ECU when it is in reverse, etc.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jlicrx &raquo;</TD></TR><TR><TD CLASS="quote">the engine wiring for the HF is the same as the Si, except for the EGR Valve, which is the thing in the second picture - it is mainly for emissions and shouldn't affect mileage much if you leave it disconnected, however, if you are running the HF ECU, you will get a code for EGR - the close coupled cat is mainly for weight savings and shouldn't affect mileage if you ran one from DX or Si - you probably won't get quite the mileage as you would in the actual HF since you have a heavier car and the HF has other sensors that the ECU reads to change the amount of fuel being supplied - things like switch on the clutch pedal to tell ECU when clutch is depressed, switch on back-up lights to tell ECU when it is in reverse, etc.</TD></TR></TABLE>

woah thats crazy..didn't know HF was that high-tech ahha, but wow i'm guessing these are all leads into the HF ecu and could i add them if i had an HF chassis to go rummaging through?

 

If you want to hook up egr you'll need an egr control box, Iono of the newer ones will work though, so it's prolly better to just get an hf one. Anyway, how does a clutch pedal switch affect fuel trim? I believe all crxs/civics came with that. My pedals are from a civic and it has a spot for it (Which I don't have hooked up). All it is is a killswitch so you can't start the car in gear.

 

this car will be going through inspection so, the EGR is def. needed in that case rite?

edit:added a tranny question too..

 

here are HF vacuum connections:

 

The HF flywheel might weigh less, weigh it an see. The cx/vx does. I have a cx flywheel on mine for MPG purposes. Anyway, all 90-00 clutches are the same and 89 is compatible though the disc is smaller.

 

thanks, jlicrx, that vaccum diagram will def. come in use...

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SVOboy &raquo;</TD></TR><TR><TD CLASS="quote">The HF flywheel might weigh less, weigh it an see. The cx/vx does. I have a cx flywheel on mine for MPG purposes. Anyway, all 90-00 clutches are the same and 89 is compatible though the disc is smaller. </TD></TR></TABLE>

so ANY d-series clutch will mate rite up? cuz i have too many d-series clutches just laying around in my garage heh.

arite i gotta head out to school for a bit, i'll be back in a lil' bit thanks for the help so far guys..and any suggestions on the last part, about the cam gear play with the timing belt off effecting the timing?

 

Your clutch goes with whatever transmission you have. If its an 88 transmission, it'll have 21 splines on the input shaft, 89+ is 20. The 88-89 used a smaller flywheel as well.

Basically, use a matching clutch\flywheel combo. If you have a 89+ transmission, you can use any 89+ flywheel and clutch. If you transmission is 89+ and the Si flywheel\good clutch is 89+, you should be good. I dont believe I've heard of the clutch being any different between trims, but I could be wrong. And if anything, I would think the Si flywheel would be lighter so the engine would spool quicker.


EDIT: Google CRX Workshop Manual. Download it and it'll tell you how to do your timing belt. On SOHC's its pretty easy.

And any header will work (I actually have a DC Sports one for sale...). The HF manifold was designed like that to save weight (less cast manifold, more cheap tubing)

 

Si flywheel is 18 pounds, to my knowledge all d series flywheels are besides cx and vx, dunno about hf though.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SVOboy &raquo;</TD></TR><TR><TD CLASS="quote">Anyway, how does a clutch pedal switch affect fuel trim? I believe all crxs/civics came with that. My pedals are from a civic and it has a spot for it (Which I don't have hooked up). All it is is a killswitch so you can't start the car in gear.</TD></TR></TABLE>
well, it must affect it since the ECU gets that input

 

I can get that control box for you at the junkyard if you want. PM me.

 

hmm ok, well i'll get home and measure the difference between the HF and the Si flywheel(s) and what do you think the HF ECU does with the knowledge of the clutch enaging/dis-engaging or even the reverse light? and i see how it feeds into the ECU so, it must be doing something!

 

I just think the ecu controls whether or not the car turns on based on the switch. Just like with the A/C the button goes to the ecu and then the ecu runs the a/c clutch whatever.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by pr3d &raquo;</TD></TR><TR><TD CLASS="quote">hmm ok, well i'll get home and measure the difference between the HF and the Si flywheel(s) and what do you think the HF ECU does with the knowledge of the clutch enaging/dis-engaging or even the reverse light? and i see how it feeds into the ECU so, it must be doing something!</TD></TR></TABLE>
the HF flywheel weighs 15 lbs. - the main reason that the clutch switch is run thru the ECU on the HF is that the HF has a shift light controlled by the ECU thru the VSS that tells you when to shift for fuel economy - the ECU turns the light off and resets it when the clutch is depressed - on the Si and DX the clutch switch does not go thru the ECU, just to the starter relay - as for the back-up lights (also has input from brake lights) i don't have a clue - my guess is that Honda figured you didn't go that fast in reverse, so cut out some of the fuel - probably the same for the brake lights - on the brakes, you don't need fuel - i own an 88 HF and out of curiousity as to whether these inputs also controlled fuel, we unplugged the wires from the ECU at pins B7, B9 and B11 and drove it for a while and the mileage did go down close to 5mpg - plugged them back in and the mileage went back up

 

Ah, shift light, forgot about that.

Brakes do not influence ecu control of fuel economy related things. What does is throttle opening and RPM, 0% throttle and 1100+ rpm = engine braking = no fuel used.

This is in the honda obd training manuals as well as observed by me, the owner of a fuel economy display that does instant, trip, lap, tank, and other neat things like monitor engine on percentage per distance and fuel injector pulse width.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SVOboy &raquo;</TD></TR><TR><TD CLASS="quote">Ah, shift light, forgot about that.

Brakes do not influence ecu control of fuel economy related things. What does is throttle opening and RPM, 0% throttle and 1100+ rpm = engine braking = no fuel used.

This is in the honda obd training manuals as well as observed by me, the owner of a fuel economy display that does instant, trip, lap, tank, and other neat things like monitor engine on percentage per distance and fuel injector pulse width. </TD></TR></TABLE>and you have a CRX HF?

 

DX with hf tranny.

The point is, however, that if you're engine braking with the brakes on or engine braking without brakes you're using no gas in any case, and if you're out of gear you're out of gear. The HF was not built with lean burn capability such as the vx was.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jlicrx &raquo;</TD></TR><TR><TD CLASS="quote">the HF flywheel weighs 15 lbs. - the main reason that the clutch switch is run thru the ECU on the HF is that the HF has a shift light controlled by the ECU thru the VSS that tells you when to shift for fuel economy - the ECU turns the light off and resets it when the clutch is depressed - on the Si and DX the clutch switch does not go thru the ECU, just to the starter relay - as for the back-up lights (also has input from brake lights) i don't have a clue - my guess is that Honda figured you didn't go that fast in reverse, so cut out some of the fuel - probably the same for the brake lights - on the brakes, you don't need fuel - i own an 88 HF and out of curiousity as to whether these inputs also controlled fuel, we unplugged the wires from the ECU at pins B7, B9 and B11 and drove it for a while and the mileage did go down close to 5mpg - plugged them back in and the mileage went back up</TD></TR></TABLE>

wow, i need thoat extra edge of those 5mpg, so i'm gonna have to find a junked HF to rape these things off of. are those pages out of the generic 88-91 EF DF manual found everywhere on the internet?

 

ok i think someone already mentioned this but i can throw on my Si clutch on this HF flywheel rite? i shoudn't have any problems with it working?

 

LOL Bump For the Guy Who bought my Old HF Drivetrain!!! yeah man you can use any '90-91 d clutch on that hf flywheel there, all the bolt patters on the Pressure Plate are the same. Follow that diagram posted for wiring up the EGR, i had the whole control box and vaccum lines months ago but unfortunately i've since thrown it all out. Good luck with the swap man lemme know how it turns out.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by godruler &raquo;</TD></TR><TR><TD CLASS="quote">LOL Bump For the Guy Who bought my Old HF Drivetrain!!! yeah man you can use any '90-91 d clutch on that hf flywheel there, all the bolt patters on the Pressure Plate are the same. Follow that diagram posted for wiring up the EGR, i had the whole control box and vaccum lines months ago but unfortunately i've since thrown it all out. Good luck with the swap man lemme know how it turns out. </TD></TR></TABLE>

whatsup, yea i've finally threw the motor on a stand and started taking it apart and stuff, but yea thanks for the motor and all and thanks for the d-series info, i just wanted to be sure, the EGR wiring doesn't look too bad either but the vaccum i'll have to find off of an HF i guess, i'll look around in our local yards here for an HF to rape parts off of! but yea its coming along AWFULLY slowly haha, i've just been too lazy all summer, but before iknow it summer will end and school will start again and life's gonna suck! haha but thanks again man..