I've seen that an aftermarket EFI system or carb can make quite a bit more power on an otherwise stock 6 port engine than a stock EFI system can. I can't really afford to do a proper EFI system, and I actually like the idea of simplifying my engine bay with a carbed intake.

The three options that seem to be the best are:

Weber 48 IDA-style
Weber 45 DCOE-style
Holley style

I know that generally the IDA is more of a race carb and makes most of it's power up top and lacks a choke, so I'm not really considering it, because this is still a street car in the end. So that leaves the DCOE and the Holley. Anyone care to recount any personal experience with these two setups?

It seems like the Holley would make more power overall, but it is more expensive (950ish from racing beat for the whole set) and I don't really like the way they look. The DCOE can be found for as little as $450 and the intake is only $150, but it would not be pre-tuned for rotary applications. I don't mind playing around with the tuning (in fact it sounds actually kind of fun, tuning with a screwdriver and jets rather than fuel maps and a lap top)

Basic questions:
Which would be more streetable?

Which would have better throttle response? (big thing for me)

Which would deliver poorer fuel mileage?

Which would give the most exciting powerband? (not necessarily the most power)

Which would be the easiest to get up and running?

Is it worth it to switch from the stock EFI system to a carb? I just don't like the complicated nature of the EFI system. I don't care that much about fuel mileage because it's not my daily driver. So many bugs to work through just to solve simple problems. I also feel like it strangles the engine. That dumb air meter and the compromised geometry of the manifold. I feel like it's limiting the engine. I simply want the car to be more fun.

edit:
http://cgi.ebay.com/ebaymotors/Weber...ht_3818wt_1165

Is there a reason that carb is so cheap?

 

I have to recommend sticking with EFI unless you're just really allergic to electronics. Trust me when I say that carbs have just as many headache-inducing issues as EFI, they're just different. Especially if you aren't getting one that's pre-tuned; expect to spend at least the cost of a basic MegaSquirt in jets.

Personally, my choice would be an S5 NA intake manifold with a MegaSquirt. It'd be much cheaper than a carb anyway, and you get to toss the restrictive MAF. That's precisely what I'm planning for my REPU. Lots of flow, EFI driveability, and cheap.

That said...

Don't bother with a 45 DCOE; if you want a DCO, get at least a 48. The DCO also lacks a (useful) choke, but you don't really need one anyway. Honestly, if I were to do another carb setup, even on a street car, it would be an IDA. The powerband and driveability will be fine as long as you choose your venturis correctly and tune it well. My only experience with Holleys was on a supercharger, and it honestly really sucked. The fuel slosh problems were extremely irritating, way worse than my Weber setup or even a Nikki. Changing jets in a Weber is much more pleasant than a Holley, as well.

 

My brother has a holley carb on his small block ford, and it has been pretty problematic. Always leaking and such.

 

streetable is all in the tuning, if you tuned all 3 carbs properly, they should all be really really close. if you go racing, or try turning the holley stinks. the lack of choke on an IDA isn't a problem, or its only a problem for like 30 seconds when you start it cold.

mileage; the holley has some potential here, as it has the progressive primary/secondaries, like a stock nikki, although in practice i'm not sure that careful tuning of the other two would net much difference.

the powerband depends on the selection of parts; manifolds, exhaust, ports, etc. the carb really only supplies the fuel. the IDA however uses a shorter manifold than the DCOE, so in theory it should be more top end, vs the DCOE being strong in the midrange

the easiest would be the RB kit, just because its a kit. my car has an IDA, and i've been thru it a few times, so for me the IDA/DCOE would be really quick to do.

and it IS fun to go thru the carb, it took some time, but i have a system, you start with idle, and work your way up, and once you've done it a few times, you can tune the carb in like half an hour? EFI is the same, but it takes 10x as long

 

I like to turn, so the holly doesn't sound appealing.

I think an IDA would be wasted on a stockport engine to be honest. I don't want to turn more than 7500rpm. Does the DCOE sound like the best fit then?

 

on a weber, the 48 is the throttle plate size in MM, so a 48IDA and a 48DCOE have the same 48mm throttle plate diameter.

the IDA and DCOE other than that actually share venturis and jets, so except that one is orizontal and the other isn't they are almost the same.

part of the tuning is that you can change the venturi size on both carbs, so you can set it up for basically any engine.

 

Well I was more speaking general about runner length of the DCOE vs IDA manifold.

 

Well, I will say that I rode in snivley whiplash's car, which has as far as I know a stock GSL-SE block with a Dellorto 48 DHLA (essentially the same thing as a 48 DCOE), and it felt pretty quick and had a nice powerband. Excellent driving manners, too; he's really got that thing tuned well. If you go that route, I'd recommend asking him how he's got his set up.

 

Will do.

 

I love how the efi works on my gslse.

A buddy did the rb intake swap with and edelbrock 650 on his, really no difference in power, and the efi maintains better torque and throttle response due to the functioning aux ports.

If your heart is set on it, do the 48 dcoe and keep the stock lower intake with functioning aux ports and add atkins sleeves.

 

I would definitely keep the six port system functional. Or in my case, make it functional

 

well to start off with. my car was just assembled with a used 6 port a side draft dellarto and racing beat upper intake mated to a stock lower with block off plates. to finish off the set up is a r/b header(single pipe) a pre silencer and a magna flow stainless muffler.

When I got the car to ran very poorly and needed a lot of tuning to make it run ok. Still not correct but was drivable. engine lost an apex seal short time later due to worn seal grooves in the rotors. so a rebuilt engine went in. Broke it in with the old set up and then started tuning..........man what a chore.

tuning a dell is tough, had a hard time figuring it out. got some help from racing beat tech department on there jetting and mods for the 4 port and just added some jet to it...omg what a nite and day difference. started really easy with no choke, idled low at 800 rpm had a great transition and would red line easly.

the real trick to carbing a six port is enough air and fuel to make good power. a wide band is a must for tuning. I estimate I am making around 165 hp, and it drives as good as any efi engine. smooth and responsive, I drive it everyday. mine is running wide open no axl. port actuators and pulls as good as a ported engine, breaks the tires loose accelerating in the dry in 1st and 2nd at full throttle, what more could I ask for

 

You made my day. Weber 48 DCOE here I come I'm just going to pull my aux-port sleeves, I'm tired of dealing with it. I can feel no difference (or very little) in low end response or power with them wired straight open, and the complication just isn't worth it to me. Feel free to post some videos snivley!

Edit: After looking at your mod list, our cars would be almost identical in terms of upgrades. The only difference is the type of muffler and brand of wheels! I've got identical suspension, wheel size, and exhaust.

Edit2: And for the GSL-SE lovers, I'll keep all of the EFI stuff so that I could put it back to original in the future if I want. Anyone know if I can keep cruise control? The module doesn't seem to be too intricately tied in with the EFI system, but I could be mistaken.

 

Double check the wiring schematic. IIRC the cruise is a separate circuit. Just need to adapt the throttle. But DOUBLE CHECK THE SCHEMATIC.

I'm about ready to ditch the GSL-SE swap into my 12A in favor of a MS setup. I just wanted something I didn't have to tune!

 

glad I could give you some input, my set up is great runs very well and makes great power for a daily, there is a lot of info in the archives of what i have done to make it correct just do a search