Ok, this topic was requested, so I will oblige.

The quick version can be found at http://linus.highpoint.edu/~hleach/speed

First off, this method gets expensive quick, I'll try to give prices as I go along.

To go with a dual carb conversion, you need an Si engine, or at least the head:

It's a true 12 valve head, and gets rid of those pesky CVCC ports. Cost: $150 junkyard price for engine and head is what I paid, machine work and rebuilding the head via a machine shop: $450.

After that, you need the carbs and manifold!
http://www.carbs.net has the kit you're after if you want to go the weber route. Kit number K703 if I remember correctly, which comes with a TWM manifold [pierce also makes manifolds, they work with webers or mikunis]. ~$1200 new for carbs and manifold. Used carbs can be had, but jetting will likely not be close enough to see a gain and you should get a rebuild kit, trust nothing on a "new" fuel system with used components.

Now, you have the head, you have the carbs, but you can't use the mechanical fuel pump on the Si head, so now you need an electric fuel pump:

mine is a solid state pump [noisy as hell], but you only need something that will put out about 5-6 PSI, and then after that you should still get a low pressure system regulator, Purolator makes one that is adjustible from 1/2PSI to 6PSI, goes inline with your delivery line under the hood, sorry, no pic. Cost of pump ~$45, cost of regulator, ~$20. Weber carbs like about 3.5 PSI to run correctly.

Ok, got the carbs, got the manifold, got fuel to the carbs, you aren't going to make them breathe through a piddly stock exhaust manifold are you?

This header from DC is ceramic coated, I believe SS headers are available as well, I have no complaints with it. Cost ~$180 when I bought it I think.

PROBLEM: The only headers you'll find for a First Gen CRX claim they are for an Si, but the exhaust ports on the DX and Si heads are the same, so where's the problem?

The DX pan is on top, the Si pan is on the bottom. With the DX pan on the car, the header WILL hit and you won't be able get it bolted in place. Change out the oil pans, and your problem goes away.

This picture has a few things that I didn't know were wrong at the time, but found out later, I'll explain what I found.

Behind the head you can see that there is a brazed brass "U." This was needed to connect the water line from the head to the block without kinking the line, just don't touch the brass when the engine is hot. Ok, now look at the vacuum fittings on the intake manifold. The one on the right goes to the brake booster, this is not a problem, in fact, it works EXTREMELY well. The one on the left, however, is connected to the PCV valve, which eliminates all the negative pressure in the manifold, not letting the carb work. If you get the TWM manifold, don't bother to drill and tap the second vacuum fitting boss like I did.

Once you get everything running, you'll find out real fast that the car is quicker. MUCH quicker. You'll also realize that it can get away from you faster than you can stop it and that you have a LOT of money invested by this point. Protect your engine.

This isn't the most recent pic, but you can see what is currently being used for my daily driving setup. The MSD 6AL ignition is set at 6K RPM, there really isn't a reason to rev higher on the stock Si cam. Near the firewall you can see the round silver item that is setting on the intake tubing; that's the fuel pressure regulator. I also made a backing plate for the carbs out of fiberglas, which is where the fitting for the PCV tube goes now, between the carbs; and made an air box using sheet metal and a MIG welder for street filtration while keeping the air horns in place under the box [they help smooth out the air flow before it gets to the main jets]. To complete off the street air filter system, the intake tube is from an 88 Dodge Caravan [junkyard just gave it to me], and the filter is a 7" tall go-kart racing air filter [you might laugh, but it works, and is only $5 to replace]. Since that picture was taken, I replaced the shrink wrap going under the air box springs [screen door springs, $3 a piece from a hardware store] with spiral wrap from radio shack, added a Blaster SS coil, and an Accel 8.8mm custom length straight boot wire set [made for a V-8, cut to length, great if you have the crimpers to use something like this, I do]. Cost: 6AL- $200, SS coil- $35, V-8 wireset- $40, airbox/backing plate- negligible, shop supplies.

I have to warn you though, if you go through this much trouble, put in a stronger than stock clutch while you're at it. My stock replacement clutch was about a year old and strong, but it is quickly dying. LSD is highly recommended as well. This setup makes about 140 crank HP, and is still 100% CSP autocross legal

For more info, also check out the First Gen CRX list run by yours truly: http://groups.yahoo.com/group/CRXmk1

Harry Leach
owner/moderator
CRXmk1@yahoogroups.com


[Modified by 1stGenCRXer, 7:05 PM 1/22/2002]

 

Nice pics. I haven't seen too many 1st gens in my area still running a carbed setup. But from the looks of your seyup I don't see why they wouldn't. I like the setup and you have given me some ideas for a project.

 

Well... Honestly, carbs are a PITA if you don't have extensive experience with them. They take constant TLC, but they let you do whatever you want without failsafes common with EFI setups coming into play. If my car started off EFI, I would have kept it that way, I may even do an EFI conversion later on in the car's life and switch to Toda individual throttle bodies, but for now I'm satisfied. The other big deterent for people is the cost of carbs, they're down right pricey.

 

Already has a lot of "Zipp" to it Has the B16 second gen CRX guys removing weight to get even with me, time to get a clutch and break their hearts again Thanks for the compliments

 

Damn!!! well real nice setup 1gencrx, I thought it was less job than that, But i'm ready to do it, a bit a t the time. I don't want to augment the displacement of the engine this is why I want to keep the stock block in it's actuall place, Do you know a cmpagny that make a set of piston /rings for that engine?? Thanks for the info Man i'm really pleased to see that. very nice job, Impress by the power it goes out at the end!!! very cool kit. Is it actually possible to get a normal manifold machined to a double carb convertion???
thank a lot for the fast reply!!
see ya

 

Oh yeah, I forgot to add that the block has been bored .040 overbore [as per SCCA specs], and balanced/blueprinted.

To answer your questions:
yes, http://www.rivergate5speed.com/honda_performance.html near the bottom;
and probably not. The 'normal' manifold has all sorts of weird extra ports. You could probly use the gasket face flange and make the rest of the manifold yourself, but that's more work than I cared for.

 

I love it, so nice!!!!!!!!!!!!!!

 

beautiful!

-Seth

 

Well Won't cost me nothing to get a try to get the manifolr donee myself, then if it get the off, I won't cry very loud to buy another one!!
I really like your setup, Thanks a lot fot the pics!!

 

glad to see ur up and running i cant seem to find the keys for the 87 crx si me and phattwhippincrx are building soon.getting rid of the ew4 putting a d16a6 in possibly with a 14b turbo. do u plan on running it at the track soon?

 

EW4 you say? What do you plan on doing with it once you swap?

As for the track, the car is being built for CSP autocross, and some track events, suspension will be coming in the summer. I've run it at an 1/8 mile drag strip once, but the times belie the power since I was smacking redline without going anywhere immediately after the 60' mark. 60'- 2.2 sec. 1/8 mi-10.6; I made two other runs that day, but the times got worse and worse [clutch got so bad that I actually turned a 16.1 in the 1/8]. My drag racing days with that car are done, or at least until I can get a clutch willing to hold all the power.

Again, thanks for the compliments everyone.