D15b Dual carb upgrade options?

[GIVIT8]

hey there, new to NZHONDAS. Keen to try a carby turbo setup, but i would like to know if anybody knows what other carbs will fit and provide more air/fuel?. Is it possible to make these stock carbs flow more or am i better off going for another brand???

[DURTYEF3]

SEARCH!!


And welcome

[Horny_Devil]

ur probably better off doing an eninge swap

[VTAKYO]

Don't even bother. Honda carbs are shit. I had an EG with dual-carbs and nobody would touch them. To tune, or to modify; they are just a hassle and too complicated with all their emissions crap. Working the engines causes fuel consumption to turn to shit, and you don't really have the performance to justify it. Tuning the carbs to actually make the turbo setup remotely efficient would be extremely expensive, if anybody could even be bothered doing it. Different jet-setups will be required to fine tune; in which case you will be hard pressed to find aftermarket jets for Honda carbs. So, that means a custom plenum, and aftermarket carbs. Something like side-draft Delloroto's. The problem also arises that carb's don't really like being pressurised, which makes a whole world of problems regarding balancing the carbs; including matching the pressure of the fuel and the pressure of the boost etc. In the end you would need a deep pocket to make it work; in which case you would have spent enough to do a B-series swap (which would be a whole world more reliable, and more than likely make more power).

There is a reason it hasn't been done. One guy on here suggested it once, and was actually going to go through with it. He got wheel sponsorship and everything (inside joke )... his thread ended in 8 pages of humiliation. Don't fall victim to the same treatment, give up now!! The easiest thing to do would be a D15B VTEC Turbo. Could be done for less than 4 or 5g I'd say.

[Plague]

Originally Posted by VTAKYO

The easiest thing to do would be a D15B VTEC Turbo. Could be done for less than 4 or 5g I'd say.

And even then I've been told by mechanic mates that your be better off with an engine swap. Can always turbo the new engine later it you want to pull the chicks with your sick boost

[VTAKYO]

Exactly. The only point of it really is for ease of swapability. Other than that... it's just really useful if you have a desperate need for easy boost.

End of the day, B-series leaves you plenty more options and expansion.

[GIVIT8]

na im sure the keihin dualcarb setup on a d15b will handle a few pounds. Just got to boost refence the carbs, so basically the pressure on the outside (atmosphere) is the same as the boost pressure, im sure you can just plumb a fitting into the intake runner after the carb to correct the pressure. ive been looking all over the net but havnt had much luck on this particular mod. i understand what it all means but i dont know how far to go as far as stripping the carbs of emissions vac lines etc to properly construct a plenum.

[GIVIT8]

So yeah. i dont think that an engine swap is the way to go. why swap to a b-series? ive got a B20b vtec in my DA so i see no point in having two cars with the same engine series.

I dont want a powerhouse just a mild turbo setup with a different taste.

If nobody can help with the carby question, then what is the easiest way to EFI? replace head, intake man. and engine loom? or just use sohc intake manifold and ecu from which model?

so, as you can see there are pros and cons either side of this debate but i was hoping somebody has found something i can relate to in regard to information about boosting thru these keihin dualcarbs.

I keep reading replies like, swap your engine... waste of time...
i believe the dualcarb D15b to be quite a performer for what they are, smoking 2.2 sohc vtec accords (not hard), 1600 sohc inj zxi's, anything with a 4(gay)age in it even 20v with vvti, SR20 p11 primera, stock starlet GT.
so with a bit of boost =

[Ped Rac3r]

If you really want to turbo it, it will be easier to swap to EFI and run a low boost setup and make 120-150kw at the wheels.

You'll need the ECU, loom, intake mani (and all other parts to go with it, injectors, TB etc) and a fuel tank and pump from a D16 or D15 that is already EFI.

I have a SOHC ZC with the dual carbs, and like you said it goes alright for what it is (and for 220k on the clock lol). But the Keihins arent that great, a couple people have made some power from them. One made 122hp at the wheels on a D16, Level 2 Bisi cam, P29 pistons etc. You could head down that route and throw on some side draft Webers or Dellortos and make 130-140hp atw.

But best bang for buck would be engine swap (doesnt have to be a B-Series, H or K would be just fine ), or run a low boost setup on your D15B.

[SierraShack]

A single Webber DCOE could be ok twins would use just to much fuel. but if you really want to go turbo go efi. or try and find a mg maestro or metro turbo carb, A Webber 32/36 or SU carbs with a blow though set up works not great though(from experence).

[Trivium]

Originally Posted by GIVIT8

ive been looking all over the net but havnt had much luck on this particular mod.

Because nobody in their right mind would try it, when its easier, cheeper, more tuneable, more reliable ... hell its just better. I see that you might want to be mechanically different here which is fine but WHY?

Yes you think your engines a bit of a preformer but adding a snail isnt the way to go for more power/fail on that one sorry

The cost of turboing the carbied engine, then finding someone to tune it are just stupid...when you could chuck a d15b in there and turbo that - you'd get more power for less fuel and it'd be a heck of alot easier. Factor in the billions of dollars that car companies spend on research, how many carbie turbo cars make it to the consumer? Doesn't take a bright spark to work out why....

[GIVIT8]

nice, nice, way to go with the diss.
anyway rather than argue, i was just feeling around on this subject. Keen to see what people have in the way of information about modding them or boosting thru them. Yes i was striving for something a little mechanically different, and at this stage dont really see any downfall when using a carb turbo setup. Just seem to get the same answer - change the carbs. Also, weighing up my options at this stage it does seem easier to go efi swap, rather than fabricate a manifold to fit some aftermarket carbs. Then im not sure what that little black box will make of being disconnected. thanks for your time anyway chaps.

[Ped Rac3r]

Originally Posted by GIVIT8

dont really see any downfall when using a carb turbo setup

There is, like stated above, tuning the carbs for a turbo setup will be a bit more complicated rather than adjusting tables on a fuel/ignition map, and getting someone to do that for you will be just as complicated (although if you do your homework and buy a bunch of different jets to try along with a a/f meter you could do it yourself).


Which black box are you talking about? the one with a bunch of vacuum lines coming out?

[VTAKYO]

Yep, I took my old dual-carby EG to Christchurch's top carb specialist and they wouldn't even touch them. So, as much of a pain as they may be to tune, finding someone to do it is even more of a pain.

[GIVIT8]

yeah the black box im referring to has all the vac lines goin to it with allsorts or check valves, solenoids etc for the carbies secondary control and to lean off while cruising etc,.... sounds complicated i think ill definately go injection after all or this.

so any thorts on an appropriate head swap for efi?

im not going to spend heaps i just want to leave at least the block intact and fit another head and injection manifold, engine loom.

been looking at stock piston specs and head chamber volumes etc..
wouldnt mind finding a ZC DOHC head for the D15b and fit that, then the compression is nice and low. well at least what ive read so far. no doubt ill know if im wrong. could be an interesting frankenstein 1500 dohc turbo???

[Tompen]

Dont think itll work, im pretty sure you cant fit DOHC heads on SOHC blocks. You could pick up a whole injected D series motor for pretty cheap though. Plus youll need the whole fuel lines and loom so its not as simple as swapping the head.

[doo0T!doo0T!]

Well you can actually, i did, my crx has a sohc block, it just required a bit of fiddling around.

I'd love to see you go away and make it successful and come back on here and tell everyone to pucker up for your ass......but......if I were you I'd either ditch the carbs and convert to efi before you start your turbo mission or go see rogercordia (another iside joke) and get a mitsi cordia turbo carb and turbo and use that. At least then the carb will be set up for boost already.

[Tompen]

Much fiddling around? More than LSVTEC?

[doo0T!doo0T!]

Had to re-drill the holes for the head bolts out to 14mm as the sohc only uses 10mm studs and I wanted to go out to 12mm.
One of the holes does not align by a few mm but when you re-drill out to 14mm it's ok because there is enough play to get the new stud through.

[Trivium]

Originally Posted by GIVIT8

nice, nice, way to go with the diss.

We're not dissing you here, just offering advice. Theres already been one guy come on here, blowing on about making a carbie turbo and fail when he experienced all the problems that we said he'd have and in the process make himself look like a tool

[doo0T!doo0T!]

But at the same time it's great do do something and make it successful when everyone tells you you're dreaming.
Everyone laughed at me when I said I was putting the dohc head on the sohc block (not here though, mostly on US based sites), these NZ boys are cute and cuddly in comparison to the way the yanks like to cut people down, damn internet guerillas

Don't be disheartened by everyones seemingly negative attitude on here towards your idea(s), remember the majority of people on car forums are bolt on queens and think if it's not on a shelf it's obviously not possible, economical or worthwhile.

prove them wrong, go on I dare you.

[Horny_Devil]

ive proved a few people wrong but i dont think id do it again, it just costs to much time and $$$ to do and at the end of the day it just isnt worth it

[GIVIT8]

ooooh thats what im after i think ive read another of your posts in regard to this head swap!!!! are there different versions of ZC head? which one is best to use? and why?

im keen to leave the block intact because it has only low mileage it may as well stay there. beats only getn $50 for a dual carb d15b engine. and then of course the engine number hasnt changed either, for the sake of a few late nights and cold coffees stacked up that you forgot about lol, id rather swap the head and try something different. hey if it dont work ive only wasted a $50 motor.

sounds like i need a donor eg with efi?
and a head and intake manifold from eg zc dohc? so i can fit h-series throttle body?

[doo0T!doo0T!]

^ go EF not EG unless you want to do an obd1 efi conversion while your at it.
Hang on a minute, is your car an EF or EG?

If you want to use the H series TB just get the EG intake manifold and fuel rail.
EF dohc zc bits are heaps easier to find than EG.
EF3 and EF7 ar ethe chassis codes to look for for all the bits you need.
But if I'm going to give advice I'd say flag the 1500cc block and all the farting around to swap it and if your getting all those donor parts anyway you might as well get the whole engine while your at it. And gain another 100cc in the process.
Keep your gearbox though it will have a 4.25 final drive while the ZC has a 3.8:1

If I were in your shoes and I really wanted to be different I'd flag EFI and flag turbo as well, adapt a dohc head and distributer and put a proper set of carbs on it like dellortos, mikuni solex or even webers, failing that a set of 4 big bike carbs.

That way you wont need to change the fuel system and all the wiring for EFi and ecu etc etc. It would be heaps easier and still be totally unique, because I get the feeling thats what you're actually after.
Would be a super clean engine bay too.

[GIVIT8]

EG Civic ferio MX