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D15b4 dual carb

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D15b4 dual carb

Postby Psyfron » Mon Sep 29, 2003 10:51 am

I know that this topic has already been addressed below however i dont think an acceptable answer was given so ill ask again and be a little more specific....

I want 2 know if anyone has done up a d15b4 dual carb?
(im thinking twin 45mm side draft webbers with a more aggro cam)

everyone always says do an engine swap, but thats not what i want.... y b like everyone else... im begining to believe that if i spend the $4000(australian dollars) that it would take just to get a b16 in there, on mods to this engine then ill beat a b16 anyway... its only a 30kw difference.... if i cant find that in my engine with $4000 to spend then there is something wrong...

i know there was a vtec version of the d15 and if i could find one i could use the efi and the head from it but i dont really want to do that either...

i just wanna know WHAT can be done... has anyone done it and what are the gains? (am i really going to waste my time?)
Psyfron
 

D15b4 dual carb

Postby teal_civic_mobile » Wed Oct 01, 2003 1:53 am

i was wondering the same thing to be exact. i recieved a jdm d15b engine w/ some sorta of manifold on it. it wasn't fully there just two rubber hoses to a short manifold no carbueraters.. so yeah if u find anything out post it ok...
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Re: D15b4 dual carb

Postby dualcarby » Sun Oct 05, 2003 10:19 pm

"Psyfron" wrote:I know that this topic has already been addressed below however i dont think an acceptable answer was given so ill ask again and be a little more specific....

I want 2 know if anyone has done up a d15b4 dual carb?
(im thinking twin 45mm side draft webbers with a more aggro cam)

everyone always says do an engine swap, but thats not what i want.... y b like everyone else... im begining to believe that if i spend the $4000(australian dollars) that it would take just to get a b16 in there, on mods to this engine then ill beat a b16 anyway... its only a 30kw difference.... if i cant find that in my engine with $4000 to spend then there is something wrong...

i know there was a vtec version of the d15 and if i could find one i could use the efi and the head from it but i dont really want to do that either...

i just wanna know WHAT can be done... has anyone done it and what are the gains? (am i really going to waste my time?)


I have the ZC SOHC Dual Carb in my 4G4D, with the same carb setup as you.

I will give you some hints on modding those carbs, purely coz you drive a honda :)

First, get two motorcycle cone filters, the ones for performance bikes. Then, remove your stock airbox completely, and block off all attached piping. DO NOT block off the breather hose that goes from your valve cover to your stock airbox, get a breather filter for this one. Remove mesh guaze covers and spacers over carb throats. Take the two cone filters and push their rubber ends THROUGH the spacers. Bolt the spacers with filters attached, back onto carb throats, without the mesh covers. File them in the dustbin... you might have to bend two little copper pipes next to throats slightly inward to accommodate the cone filters. Don't worry, they are purely for athmospherics. If you are not sure about the size filter, take a spacer, drive to your bike hop-up shop and compare sizes before buying. If you can, get filters with the rubber ends slightly larger than the hole in your spacer, to ensure a snug fit. You might have to use super-glue to make them stick... do not worry about a CAI. Carbs respond much better when they are sucking in air from 360 degrees, as opposed to from one direction only, such as a CAI. The gains from two cone-filters on the throats is much bigger than what you would gain from a CAI. Cold air is great for FI, but free breathing is GREAT for carbs...

Next, you do the Keihin CV Carb mod: You will see two silver lids on your carbs, where it says KEIHIN. Carefully remove these lids by unscrewing the screws that hold them in place. Careful not to drop any screws or dirt into the carbs once you've taken the lids off. Underneath you will see two long springs. Take out the first spring, measure it, and then cut off 3-4 coils of the spring. Now, stretch it to the original length... repeat the process with the second spring. Make sure they are the same length as before they were cut. Next, look at the open carbs again. You will see two little plastic stoppers on top of the two pipes that the springs fit over. Mine were black, so yours might be too. Remove and file them.

Now, take the springs and put them back where they came out of, with the uncut ends facing DOWN. Carefully replace the carb lids.

What you've done: The springs control the rate at which the diaphragm valve opens when you push the accelerator. After the mod the valve rises much quicker, due to lessened spring density. This vastly improves throttle response. The plastic stoppers prevent the diaphragm valves from raising above a certain point, to keep fuel consumption low. The higher the diaphragm raises, the bigger the needles open, the more fuel you get into your engine. The increased air from the cone filters and the fuel from the quicker lifting and higher lifting diaphragm means a cool 10-15HP increase...

If you want to go even more, you can machine one (1) millimetre out of the carb throats (you will need bigger butterfly's), and source larger jets from Honda bikes or Harley Davidson bikes. They use the same carbs... But this is going extreme. Harleyheads get an extra 20HP from machining and rejetting their carbs. But then they are not very streetable, and your fuel consumption goes for a dive...

But then again, performance means more air-fuel is needed.

Maybe this should be a stickey, seeing as quite a few owners have dual carbs...

Whaddya say BRACER?...
1990 honda 4 door.
d15b3 (singlecarb) thrown out.
ZC SOHC dual carb motor swap
Highly modified carbs
TNT headers
Brospeed f/f exhaust
15" TSW EVO R rims
Custom spoiler kit
dualcarby
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Posts: 41
Joined: Thu Apr 17, 2003 10:50 pm
Location: South Africa

D15b4 dual carb

Postby Fred » Mon Oct 06, 2003 2:06 pm

wow guy thats crazy true mod info! great info guy! now that trick with the trottle and the spring, I didnt understand much cause I dont have dual carb but would it have something familiar on a mpfi setup, would harley davidson as something familiar as trottle bodys for it?
speed kills.. but you'll get their faster
Fred
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D15b4 dual carb

Postby dualcarby » Mon Oct 06, 2003 3:53 pm

Nahh...

Only the carb setups use the springs. But you can use any bolt-ons for FI, seeing as they are designed for your setup. FI mods do not work well for carbs, and the carb'd honda's have always been ignored by aftermarket manufacturers.

But the fun part is figuring it out for yourself... and getting power out of it yourself...
1990 honda 4 door.
d15b3 (singlecarb) thrown out.
ZC SOHC dual carb motor swap
Highly modified carbs
TNT headers
Brospeed f/f exhaust
15" TSW EVO R rims
Custom spoiler kit
dualcarby
L1 - DPFI
L1 - DPFI
 
Posts: 41
Joined: Thu Apr 17, 2003 10:50 pm
Location: South Africa

D15b4 dual carb

Postby Fred » Mon Oct 06, 2003 6:36 pm

what times are you running on your engine and how much hp?
speed kills.. but you'll get their faster
Fred
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Joined: Thu Apr 17, 2003 11:11 pm
Location: ontario

D15b4 dual carb

Postby dualcarby » Mon Oct 06, 2003 8:59 pm

Well, I do not have exact figures yet, I plan to take her for a Dyno soon, just to get everything to work together nicely.

I have read conflicting reports that the ZC SOHC Dual Carb motors push out 112HP to 120HP. So I expect something above 120HP with all the mods I've done to her...

Thing is, she is auto, but I know she is quite fast, because I have beaten several Golf GTI's, BMW 330's, Camry 3.0's, Opel GSi's and a couple of other "fast" cars... with my SOHC dual carb'd automatic...

But then, she only weighs about 930Kg now... I put her on a diet...
1990 honda 4 door.
d15b3 (singlecarb) thrown out.
ZC SOHC dual carb motor swap
Highly modified carbs
TNT headers
Brospeed f/f exhaust
15" TSW EVO R rims
Custom spoiler kit
dualcarby
L1 - DPFI
L1 - DPFI
 
Posts: 41
Joined: Thu Apr 17, 2003 10:50 pm
Location: South Africa

D15b4 dual carb

Postby Psyfron » Tue Oct 14, 2003 7:14 am

i cant wait to try this....

im a little confused but i asume all will come clear when i have the carbs apart and i have those cone filters in my hands??

if u know any othert cool lil things like that let us know....

Thanx!!!
Psyfron
 

D15b4 dual carb

Postby Psyfron » Tue Oct 14, 2003 8:26 am

its official dualcarby is a king!
mod done!!!

:!: :shock: i didnt expect that much throttle response :shock: :!:

easier than changing oil and what an improvement!!! havent noticed a huge jump in power but i havent really tested it (just round the block but i did notice how much better the throttle is now!!!
REALLY IMPRESSED!!!!!


i recomend this to everyone!!!

the other thing is how cool the carbs sound when u give it some stick!!! :twisted:
Psyfron
 

D15b4 dual carb

Postby dualcarby » Tue Oct 14, 2003 2:05 pm

"Psyfron" wrote:i cant wait to try this....

im a little confused but i asume all will come clear when i have the carbs apart and i have those cone filters in my hands??

if u know any othert cool lil things like that let us know....

Thanx!!!


Lessen the loose play on your accelerator cable where it latches onto the carbs, by tightening it. Also good for better response. :) :)

I am still looking into further mods for those carbs, because they came on the D14A1, the D15B4 and the SOHC ZC, so quite a few owners out there could benefit from this... as I get more info, I will post it... :wink: :wink:
1990 honda 4 door.
d15b3 (singlecarb) thrown out.
ZC SOHC dual carb motor swap
Highly modified carbs
TNT headers
Brospeed f/f exhaust
15" TSW EVO R rims
Custom spoiler kit
dualcarby
L1 - DPFI
L1 - DPFI
 
Posts: 41
Joined: Thu Apr 17, 2003 10:50 pm
Location: South Africa

D15b4 dual carb

Postby Fred » Tue Oct 14, 2003 2:21 pm

any chances it would work on a dohc zc engine with 4 injectors :D , [size=9px]let me guess "NO"[/size] do you know any of those tricks for dohc zc
speed kills.. but you'll get their faster
Fred
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Posts: 1752
Joined: Thu Apr 17, 2003 11:11 pm
Location: ontario

D15b4 dual carb

Postby dualcarby » Tue Oct 14, 2003 5:22 pm

"Fred" wrote:any chances it would work on a dohc zc engine with 4 injectors :D , [size=9px]let me guess "NO"[/size] do you know any of those tricks for dohc zc


If you are one of the VERY LUCKY people who got the VERY RARE engine which was a DOHC ZC with a Dual CV Carb setup, then I could help you. But this engine was rare even in Japan, and came on limited edition Integra's... I saw one once only in South Africa years ago...

If you could find a Dual Carb setup and place it on your DOHC, I think that motor would be a beast... with carbs you can get more power than FI, and you can have a much more aggressive cam. Plus you do not need an ECU to make everything work... The 3rd gen honda's also got a carbed DOHC ZC, with an olive color cover. Apparently the DOHC loves a carb setup...

Lots of people will smirk at "old tech" like carbs, but they just do not know carbs... makes me laugh sometimes...
1990 honda 4 door.
d15b3 (singlecarb) thrown out.
ZC SOHC dual carb motor swap
Highly modified carbs
TNT headers
Brospeed f/f exhaust
15" TSW EVO R rims
Custom spoiler kit
dualcarby
L1 - DPFI
L1 - DPFI
 
Posts: 41
Joined: Thu Apr 17, 2003 10:50 pm
Location: South Africa

D15b4 dual carb

Postby dualcarby » Tue Oct 14, 2003 6:14 pm

"Psyfron" wrote:its official dualcarby is a king!
mod done!!!

:!: :shock: i didnt expect that much throttle response :shock: :!:

easier than changing oil and what an improvement!!! havent noticed a huge jump in power but i havent really tested it (just round the block but i did notice how much better the throttle is now!!!
REALLY IMPRESSED!!!!!


i recomend this to everyone!!!

the other thing is how cool the carbs sound when u give it some stick!!! :twisted:


You will feel the difference in power in high revs. The 10-15HP increase was quoted from Honda Prelude 2nd Gen performance sites, but I forgot to mention that is with an aggro cam. On your stock cam you could probably expect about 5HP extra. But to really feel a difference, you need a hot cam. In my SOHC ZC, a motor that already comes with a hot cam, my car surges like a racehorse above 4000RPM.

Oh, and the sound is good, isn't it? :D :!: :lol: :lol: :!: :D
1990 honda 4 door.
d15b3 (singlecarb) thrown out.
ZC SOHC dual carb motor swap
Highly modified carbs
TNT headers
Brospeed f/f exhaust
15" TSW EVO R rims
Custom spoiler kit
dualcarby
L1 - DPFI
L1 - DPFI
 
Posts: 41
Joined: Thu Apr 17, 2003 10:50 pm
Location: South Africa

D15b4 dual carb

Postby Fred » Wed Oct 15, 2003 3:43 pm

dual carb dohc zc :shock: no Im not lucky but its funny they only made a few of them, plus if its so beneficial, why are they not on the market? and could you make a dohc zc dual carb?
speed kills.. but you'll get their faster
Fred
L6 - Race Bred
L6 - Race Bred
 
Posts: 1752
Joined: Thu Apr 17, 2003 11:11 pm
Location: ontario

D15b4 dual carb

Postby dualcarby » Wed Oct 15, 2003 5:06 pm

"Fred" wrote:dual carb dohc zc :shock: no Im not lucky but its funny they only made a few of them, plus if its so beneficial, why are they not on the market? and could you make a dohc zc dual carb?


They did make a few of them, they are just older than our models...

And it became cheaper for car manufacturers to fit all cars with FI in modern years... plus FI maintenance generates more money than carb maintenance would. They make more money fixing your FI than they would fixing carbs...

You could easily transplant a dual carb setup onto a DOHC ZC... many have done it, specifically drag racers...
1990 honda 4 door.
d15b3 (singlecarb) thrown out.
ZC SOHC dual carb motor swap
Highly modified carbs
TNT headers
Brospeed f/f exhaust
15" TSW EVO R rims
Custom spoiler kit
dualcarby
L1 - DPFI
L1 - DPFI
 
Posts: 41
Joined: Thu Apr 17, 2003 10:50 pm
Location: South Africa

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