The idea of throwing some carbs on a D16Y8 is appealing to me. And I am just wanting to brainstorm with others the needs to actually put carbs on a former fuel injected engine.

The idea is simple at first. Replace Intake manifold with carbs and fuel pressure regulator with a 5 psi. Bing your done right? Well, on a Non-VTEC engine you would be. You would have to stare at a stupid Check engine light forever and a day but, you would be done. Unless you went with a custom spark setup like MSD. Okay, now you still have to get the guages working.

Let alone with a fat check engine light from missing injectors you know for sure that your ECU will not allow the VTEC x-over. So, the soultion to that is a simple check switch set to whatever RPM you want. (Hint: 5300)

But, there still is the issue with the irritating Check engine light. How do we get rid of that? If we remove the ECU we loose the cluster. So, what individual guages, speedo and tach? Man, this simple carb conversion is starting to look like a 1200 dollar project instead of 400.

Anyone else have any thoughts?

 

 

spade you are actually doing this??

 

Now, I have only played with carbs on dirt bikes and snowmobiles, but I think you will have some issues trying to calibrate those bastards to be effective both on and off VTEC. I'm sure it can be done. As for the timing on and off VTEC - not sure. The whole scenario would be a lot easier if you were non-VTEC.
Check engine light - unplug the bulb.

 

Thinkin' about it. Why not?
It's not that hard to find a used Carb out there.

That is a good point. Probably pretty damn hard to do. Hrm. I wonder.....I guess you could just swap the head then.




[Modified by Spade, 10:16 AM 12/11/2002]

 

besides, do you know how hard is to calibrate 4 carbs? i remember hearing everyone bitching about the old Range Rovers carbs (they use to use 2 carbs) cuz they where really hard to calibrate

 

Well, I am not looking at those carbs. I am looking at VW webers.

 

just because u see 4 horns does not mean 4 carbs.


TWIN dcoe 45 webers on a 4ag-e engine.

talking to bisi..a high performance "built" 1.6 and up engine could use the mikuni 44's and weber 45s. he told me the webers are much more precise, while the mikuni not as precise but easier to tune.

u still use the ecu for spark/starting. the ecu can run ignition without working fuel. you will have every code being thrown for all the FI and intake manifold sensors though..lol. u dont remove the ecu on a car that had one.

the ecu will keep speed sensor/ignition etc going. its doing everything it did besides fuel injection. im sure you will have some timing issues. bisi spoke about fixed timing on the d series board. search for that

a lot of people will bash carbs but talking to people who actually KNOW dual carb 4 banger set ups spoke highly of them, even about gas mileage, as i was told you can tune them for street mileage, if you know how to tune.


[Modified by JaeOne3345, 11:44 AM 12/11/2002]

 

I think you will need a switch for VTEC.

I say drop the VTEC head, go non vtec. Get a cam for it, add compression and tune those webber 45s...that would be mega-sick!

 

heyfugg it..if u run dohc vtec..just get the big bad toda D vtec killers..lol..remember..u can idle the biggest damn cam like stock on carbs.

 

Holley 4 Bbl and have the secondarys open when VTEC engages.

 

Good idea, but how are you going to engage VTEC? No ECU when carbed. Unless you go with that funny **** that GM did in the late 80s...kinda half carb half fuel injected.

 

I've heard of people engaging VTEC with those tachs that have an output for auxiliary light. Send that voltage to the VTEC solenoid to activate it.

 

Jay Yuson from Allmotorsports and Gude back in the day did that with a z6 in that damned chopped top CRX, car ran high 11's; Why don't you just go ITB's? If you are looking for cheap conversoin to carbs, you will negate any gains from them by neglecting the most costly, yet important power-producng aspect of such a conversion; engine management to go with the carbs. Reverse engineering is hard and can be beneficial, but in this case, you need to weigh the variables...cost, performance, etc. Trying to take a diamond and turn it into coal is silly...the diamond has already advanced past that point thousands of years ago.

 

ya ITB's on a SOHC d16. cool i hope to see one run one day.

 

heh, been done already.
FF Erik had a carb'd D16Z6 longblock in his CRX in '96-mid97 before he went RHD in late 97. Ran like a champ, minus the gassy odors. VTEC was on a switch, although I think Dylan could have used an RPM activator switch. His car was also converted to OBD1 using a whole OBD1 engine and cabin harness + P28 ecu.

That CRX's been through a number of transformations, come to think of it..


also had a few friends back in the dizzay go carbs on a B-series engine, forgot how those ran though. Vtec was on an RPM switch I believe too.


[Modified by Katman, 3:33 PM 12/11/2002]

 

my buddy is doing a carb setup on a stroked b16.
its gonna be killer when its finished.

 

my only question is why, with the ULTIMATE tuning you can achieve with some of the standalone ecu's what would be the benefits of switching over to carbs... they are a bitch to tune and havent been known to give proven gains in power. but maybe im just all wrong because i did read that last sentence in one of my dads muscle car mags...

 

I found this interesting article on club 4AG, and I just thought I'd share. It may or may not be useful to you, but it was interesting nonetheless. Here goes:


Using Carburetors on 4A-G

Moto-P and sections by Richard White


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The Basics

Popular Carburetor Setups

Richard White's studies on Carbs and 4A-GE


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The Basics

The usual tuning last for the 4A-GE includes for the most part, headers, muffler, exhaust, hi-profile cams, high comp pistons... But have you considered carburetors? Here's a look at the classic but effective form of 4A-GE induction.

When one thinks of high performance carburetion applications, we tend to imagine funneled intake making that nice classic induction noise... A Solex carburetor, more recently better known as Mikuni-Solex has it's origins in France, and later licensed for Mikuni Japan. It's merit however, isn't just in that orchestrated growl that we've all come to known.

One of the major advantages in using the carburetors is in it's throttle response. This is more apparent in the racing field where no filters or collectors are used in the intake. Also, compared to the single throttle injection, the Mikuni and Weber style side-draft uses dual, 2 barrel throttles for a total of 4 individual throttle mechanisms to mix the fuel and air with more control and immediacy, resulting in a positive production of gasoline/air mixture, and in turn making potentially more torque than single throttle. As you may know, there are 4 throttle, fuel injection mechanism too. And the resulting principle is similar. The two systems do have very similar, and distinct advantage over the single throttle setup. The later model OEM 20 valve 4A-GE engines utilize the latter, 4 individual throttle, which we'll cover elsewhere in this website.

So, what's so hot about using carburetors?

Well, here are some characteristics you may find attractive:

First of all, carburetors need no intervention of ECU's which can be both expensive and in most cases limited in adjustability, unless expensive alternatives like those programmable variety is in your budget. Although it takes some practice, setting a carburetor can be as simple as changing the jets and monitoring air/ fuel ratios. The goal is to match the jets within the carburetors to the required spray pattern and volume to desired mixture at a given rpm and vacuum. There are usually main jets and sub jets for various compensation, both of which have to be manually setup.

Second, the carburetors can be adjusted for much wider variety of engine setups using the same unit for the most part. Since the carburetor's adjustment is in the jets alone, it can accommodate almost anything you can imagine...as long as it's normally aspirated. (Well, some forced induction setups exited in the past but all of them are running fuel injection now)

Third and my favorite reason for the carburetors is the esthetics... The setup simply looks really nice!!!! and it sounds mean! Once an addict, you'll never go back.

So why don't you install them right away?

Well, there are some stuff you should be aware before you jump in.

Since carburetors work with very narrow, optimized range, the more you set it for peak performance in one area, the more you will run into substandard operation in other areas. For example, the carburetors cannot compensate for difference in gasoline or effects of climatic temperatures and pressures on it's own. This adjustment is left to the owner to re-adjust each time. Though Mikuni's and other carburetors do operate very well in most conditions, the fuel delivery under many different conditions is usually much more accurate with modern electronic fuel injection. And usually much more efficient.

For those who likes to tinker or wants optimum mixtures for a narrowly focused field, this can be much fun. Certainly, you will get attention from those not so inclined when you fiddle with carburetors on the spot and get good results. Race mechanics are often admired for such talent and gets gratification from that alone.

But at the same time, it's certainly a chore for those who likes to me free of maintenance tasks or depend on it to commute every day. You must be frequently prepared to re-jet them or make adjustments when weather changes dramatically. For sure, those who live in areas with drastic seasonal climate changes will have to make adjustments all throughout the year, to keep it in top shape, and sometimes even just to start the engine.

Keeping the above precautions in mind, the carburetors are seriously rewarding piece of equipment, and once it is running correctly, it's hard to smote with even the best fuel injection in terms of response and torque output...


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Some carburetor setups:

Mikuni-Solex Side-Draft

Ceased production in 1998, Mikuni is still widely available. One of the best all around units for it's drivability and performance. It may be the best all-around carburetors for use on daily driven vehicles. Kits are still available for the 4A-GE's and one of the easiest to setup. Definitely recommended for the first-timer.


--------------------------------------------------------------------------------

Weber Side Draft

Increasing in popularity as Mikuni's becoming harder to obtain, the Weber is an excellent carburetor with very accurate fuel delivery at higher rpm. Mechanically, it is easy to set and parts are widely accessible. Manifolds for the 4A-GE are widely available also. The Weber is also referenced by host of guidebooks so it's another recommendation for first-time users. The Weber's other advantage, especially over the Mikuni-Solex is it's design of the float, making the carburetors less prone to mixture changes in cornering and braking loads. It's a little bit more nervous and unstable than the Mikuni-Solex over wide rpm ranges. The jets are available in smaller increments than Mikuni.


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Dellorto Side Draft

Used by TRD for AE86 racing in the 80's, the Dellorto is an excellent alternative to Webers for racing use. It's a bit finicky for street use but what else do you expect from anything that comes from Italy... It's fun and full of character.


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Keihin FCR Carburetors

A current trend in Japan for 4A-GE use, Keihin's Flat Slide FCR 41mm carburetor was developed utilizing advanced Keihin Slide Valve technology achieved from 25 years of racing involvement. The FCR features include a progressive dual link throttle linkage for improved valve control enabling stable low- throttle operation.

The short venturi length offers quick response. These carburetors are producing very high horsepower rating on the 4A-GE and still has a nice ability to stabilize the mid range even with the use of highly aggressive cam profiles.

The intake charge has less turbulence compared with butterfly-type venturi and is the carburetor of choice today in Japanese hobbyists. The FCR's ability to resist miscalibration during cornering G's is unequalled, making use of it's motocycle heritage.


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The following section was submitted by Richard White, an expert data reference collected by a serious local 4A-GE enthusiast... enjoy!

I know you have stated that you are in the process of putting together an article about side draft carbs for the 4A-G. For Christmas I got this book, How to build & power tune Weber & Dellorto DCOE & DHLA Carburetors, by Des Hammill, 1999. If you do not already have it, it appears to be a good reference source for those interested in this subject.

At any rate, I would like to pass on what looks to be some key information on this subject. I have tried to summarize some of the key points and the many combinations of components that would most pertain to the 4A-G. I hope it can be of use to your article.

Even in this day of high technology electronic fuel injections, simple carburetors that give high performance while basically being a bolt-on item are on a cost-for-cost basis that can give “unrivaled value” for the money (especially if good second-hand carbs. are purchased).

In carbs, bigger is not necessary better. Most engines that do not run well have chokes, main jets, accelerator pump discharge jets and/or fuel pressure that are too large for the engine, and running conditions.

It is not possible to tune an engine that has some mechanical problem. Well built engines respond perfectly to correctly tuned side drafts.

Electronic Injection vs. Carbs: Overall, the performance of these injection systems (if correctly set up) is unmatched by any carburetor but the differences between fuel injection and a well tuned side draft can be very small.

It is possible that changing to carbs will mean that your car will no longer comply with exhaust emission control or other regulations in your state or country.

An increase in engine power and therefore, performance, will mean that your car’s braking and suspension systems will need to be kept in perfect conditions and up rated as appropriated.

Engines last a lot longer if the air admitted into the engine is as clean as possible. Always fit the very best filtration system that you can afford to buy. Wire mesh filters over ram stack offer virtually no protection (except from stones) and can actually upset airflow.

Ram tubes, trumpets or air horns (stacks) should always be fitted to a modified engine. As a general rule:

1. Short ram tubes are usually used for high rpm applications.

2. Longer rams are usually used to maximize mid-range response.

Webers/Dellortos require high fuel volume not high fuel pressure, i.e., 1.5 to 2.5 pounds per square inch.

When tuning your engine the cost of buying parts has to be balanced against the actual cost of getting a specialist firm to carry out this work. It is possible to spend a considerable amount of money on jets, chokes, etc.(new or second-hand) that you will end up not using.

Very small choke sizes in large bodies is not a good idea. Overall recommendation: Fit the smallest choke that will give full power.

When a slight choke size reduction is necessary to achieve better low end performance (eg: out of a corner pulling power) then fit a choke size that proves best for the overall application.

Once the carburetors have been set-up to give optimum performance, you’ll still need to check them occasionally to keep them working at their best.

Check throttle spindle synchronization, float level, idle mixture and change fuel filter at regular intervals.

Choke size:

28mm ~ 34mm

34mm ~ 41mm
Carb. Size:

40mm (40 DCOE - 40 DHLA)

45mm (45 DCOE - 45 DHLA)
There is some overlap with the other sizes. 34mm chokes recommended for 400cc/cy. With effective power between 3000 ~ 8000rpm. (40 DCOE, 34mm*)

Idle jet: 45


Air bleed components:

F6, F9, F11, F2 (rich to lean, Weber)

7850.1, 7850.6, 7850.7, 7850.8 (rich to lean, Dellorto)
The air bleed sizes are approximations and optimum sizes can only be found by testing the combinations. (50, F11*)



Main jet: 135
Main jet recommendations with ideal choke size: 135: 400cc per cylinder. Note, over rich mixtures washes the oil film off the cylinder bores and causes high cylinder wear.
The recommendations represent the rich side for the given applications so jetting down may be necessary for optimum results - but only after testing. (140*)

Emulsion tube:

F15 (Weber) / 7772.7 (Dellorto)
F7, F8, F2, F11, F16, F15 (rich to lean, Weber)

7772.3, 7772.4, 7772.5, 7772.6, 7772.7 (rich to lean, Dellorto)
Emulsion tubes are graded according to their diameters, number of holes, size of the holes and the position of these holes. (F16*)



Air corrector: 150 ~ 230 (higher numbers are leaner)


If the air corrector is too lean (large dia.) the engine will miss as it nears max rpm, and if too rich (small dia.) the engine will not produce optimum power.
The air corrector is used to tune top end performance in a very narrow range. (175*)

Auxiliary venturi:

4.0 (Weber) / .3 (Dellorto)
Note: Weber uses a totally different shape of auxiliary venturi for the 40 DCOE as compared to the 45. Beware of this fact when ordering auxiliary venturis.
If the auxiliary venturi is not large enough the engine will falter at a certain point in the rpm range. (4.5*)

Accelerator pump Jet: 40s on the high side, 35s on the low.
Find by trial and error the smallest pump jet that gives the best performance. Even with long duration camshafts it is possible to have smooth acceleration from quite low rpm in high gear (full load) without any ‘spitting back’ or engine hesitation.
The accelerator pump jets have to be large enough to remove any trace of hesitation or stumbling when the accelerator pedal is depressed but not more than this. (35*)

Accelerator pump intake/discharge valve:

no hole (intake valve)

holes in the side (intake/discharge valve)

The sizing of the discharge hole is a tuning device used to set precisely the amount of fuel injected into the engine during accelerator pump action. (no hole*)



Needle valve: 1.75
Up to 400cc/cy. Use a 1.75
The needle valve has to be large enough to keep up with the fuel demand of the engine, however , it should not be larger than is necessary.




* Standard 4A-G, distributor equipped, with 15° of idle speed advance BTDC and 32° of total advance, BTDC, and no vacuum advance. 7.5mm fuel shut off height and 15mm full droop float setting.

Back to Tech

 

u can ask here: http://www.rcrewracing.com i know u are doing single cam but, b18c with fcr flat carbs in eg, vtec works with fields vtec controller. i dont know much about the specifics, sorry

 

a friend and i were thinking about trying this as well except we were thinking of using bike carbs. we figure since most bike carbs are held to the intake manifold by rubber boots we could kinda fab something up to work on a car fairly easily. cut the intake manifold close to the head and leave enough of the runners to get a rubber boot on to clamp the bike carbs down, port the runners to have a taper so the air fuel mix won't be so turbulent. i know it sounds easy but will prolly be a total nightmare to figure out. for ignition we figured we could convert the distributor to work with an msd box to give us spark kinda like an old v8 dist just gotta get the pick up right and u should be good to go. we figured we could run vtec off of an rpm switch. didn't give any thought to gauges. also fuel system has to be changed since carbs require far less pressure than fuel injection. plus if i remember correctly there was that neon running lectron bike carbs not too long ago.

 

Why not try finding a 92-95 Civic motor with a carb setup? I've seen a few that came over from Japan with a carb on it.. So.. Just pull that whole setup off of it and pop it back onto the Y8 and you'll be good to go.. Not sure about the vtec part..

There's a shop up here that's trying to do that setup on a bored D16z6.. I'd like to see what that will run... They are expecting 11s. Who knows.

 

the factory honda carbs are usually not very performance oriented. im sure theyd be a bottle neck on a high perf build up. good idea tho. could work

 

I this thread.








[Modified by WAFFLES, 10:30 AM 12/12/2002]

 

Why dont you just buy some used ITBs off of a 929RR and convert them to fit? You'd get better performance and it would be much easier.