i wana go on the all carb diet, which one do u recommend? ;)

[turn69up]

some interesting quotes from that link

''Coming injected and dual over head cam (or twin cam) from the factory, many of the Japanese tuners at the time didn’t really know how to get much more power out of this mysterious box of resistors and wires.So what did they do? They turned to what they new best by taking off the injection manifold and strapping on a set of carbs!!''

''Even today in japan its a almost a 50-50 split between carbs and injection for a 4A-GE engine. Mostly due to workshops having limited access to a dyno’s to correctly tune an injection engine, so using a set of bike carbs and tuning on the road is the best thing they’ve got.
Even in the top level N2 races almost half the field use multiple carb setups and tune the cars by ear. Most of these are privateers but there is still a number of large well known work shops using multiple carbs''

[Deeken]

Hmm was considering setting up carbys on my 16v bigport.. but if it's shit expensive/difficult to do I don't really wanna deal with the headache, especially with what I'm going to have to do cutting apart the tail gate to fix rust..

[OniKyan]

I would suggest the 40mm Mikuni CV off a 98-01 Yamaha R1. They won't make quite as much power as the FCR carbs, however, their power delivery will be much smoother. They're also about $200-$300 for a set of four off eBay.

[LittleRedSpirit]

If you ask me the Kehin FCR is the rolls royce of carbs when it comes to response. I'm really impressed with how the FCR works on my moto, and I've been thinking for a while this would be nice.

I've been looking around for info for a while.

AFAIK the mysterious Jay from Buddyparts had some in his AE86 and it seemed to go as good as any 4age in his drift vids.
There is a manifold for AE86 4age available from RS Chita but its pricey just like all their parts.
I heard there is tuning info for them in the TRD bible but I dont have the document to confirm this.

Id be looking at 41s for a 1600. It should do it fine with the right jetting. My moto is 450cc and runs off a single FCR 41mm up to 11500 rpm, so in general volumetric terms it should be tuneable with a revvy 1600 no problem at all.

The sets of 4x41mm carbs you see on superbikes are usually aftermarket kits. New kits are around 1200US and will be jetted to suit a moto and need correcting.

So as far as costs go, the manifold is $500 or so.
The 4 carbs could be $600 to $1200 US depending whether you use new or used.
They will have a TPS available so you can run a programmable ignition computer. I think MSD makes a good one. Maybe another $500 to sort this out.
Some coils, perhaps another $50-$300 depending on what you choose.
Then you will need fuel line, a low pressure pump, another $100 worth of jets and carby accessories.
$200+ for some velocity stacks of a decent length.

Obviously the smart money is finding an AE86 specific FCR setup on a running motor. Its about as expensive as EFI to get going, if not more so, but I think it would make a different noise, make good if not great power and deliver it well compared to an efi system. Its the best way to get slide style openings into your inlet without making some custom slide throttles I think. There are a lot of veocity stacks for them, but most are small in length, wonder if anyone makes variable length stacks for them...

[OniKyan]

Indeed. Keihin FCR or Mikuni RS would be the best, however, Keihin CVK and Mikuni CV(OEM for sport bikes) would provide almost the same flow at WOT, with a much more friendly low end and power delivery, (much better for street). The carbs themselves are about 1/4 the cost, which for the average Corolla owner, could be seen as a huge benefit.

Cheap, huge improvement over single throttle injection and they both, look and sound porn.

[LittleRedSpirit]

Its not just about how much air they flow but the turbulence of the air too.

Is there a particular reason why the CV carbs would idle better, and perform better at low revs? Im struggling to see why they would be superior at any point in the rpm band. I thought that was a matter of tuning and adjusment, no matter which one you use?

[OniKyan]

I don't have any real-world experience with the FCR/RS type carb's but after countless hours of research into multi carburetor set-ups, the consensus seems to be that due to FCR/RS only having a slide, their throttle actuation is quick to the point where they can seem almost either on, or off. Therefore, a much more precise control of the throttle is required.

They also have an accelerator pump, so, If you open an FCR too fast, the engine can bog down as it allows too much flow/fuel for the given RPM. However with the CV, the throttle opens a butterfly, the suction of the open butterfly actuates the slide as necessary. Theoretically this doesn't allow the same kind of over fueling that you can get from the Flat Slide carbs.

Hope that makes sense, I'm not really an expert on the matter.

[jfallen]

CV cabies are more like a multiple SU setup and the carburetors operate on much the same principle. CV standing for Constant Velocity. Thus across the Dashpot (SU) or Slide (CV) the air speed remains the same at all times (unless the carbie is too small or at WOT.) In both cases the engine air is regulated by a butterfly type throttle body located between the engine head and the dashpot/slide.

While CV's don't have a "Choke" or "Venturi" in the traditional sense the air pressure between the throttle plate and the dashpot/slide like air speed remains constant, except in some cases of WOT. What I've said thus far is all true for steady state "cruise" motoring. What happens when you snap the throttle open??

Well, DCOE's and FCR's have an accelerator pump to make the mixture richer. CV's and SU's don't as mentioned prior. Now I'm working this out from memory on my Datsun 180B with twin SU's to here goes:

1: Snap Throttle Open.
2: As pressure drops between the throttle plate and the Dashpot the "wants’" to rise, this is resisted by a tuned spring and dashpot oil acting in a damping circuit.
3: The rising dashpot allows more air into the engine, and as it rises exposes an ever thinner needle cross section allowing more fuel into the engine.
4: As the Dashpot is resisted form rising by the spring and the damping circuit, the air speed across the venturi increases and the pressure drops thus increasing the Draw on fuel.
4.1: This resistance isn't much but it's enough. If you don't have oil in the dashpot or a too light a spring then it'll back fire as the mixture is too lean.
5: As the engine reaches steady state the dashpot begins to fall leaning out the mixture to an appropriate amount

6: For this reason SU's and CV's never feel as sharp (no matter how good a setup.) on throttle response as DCOE's or FCR's, as on initial acceleration a slight restriction is placed on the inlet in order to draw in more fuel to prevent backfires. That's not to say they feel "Doey," my old 180b was much, much sharper with Twin SU's than the previous 32/36 DVGA, but I wish I'd put the Twin 40mm Solex PPH setup on. Unfortunately it was not to be.
6.1: However this ever constant adjustment is why SU's tend to return excellent fuel economy, often on par with EFI when set up well with that in mind. Obviously if you set them up for performance like the MG crowd then well, they're like any performance Carb setup; Crappy on fuel.

Hope this was useful
Jordan

P.S: As a shameless plug: I've currently got a Twin 40mm PPH Solex setup for a 4AGE, it includes:

-Matched pair of 2 40mm PPH Solex Carburetors (Twin dual throat side drafts)
-These are tuned for a mild 2TG that was buzzing 8000RPM
-4AGE big port DCOE manifold
-Throttle linkage (NEW)
-Velocity Stacks (trumpets) (NEW)
-Air Filter Socks (NEW)

If anyone in interested give me a holler: or PM.

[OniKyan]

Keihin 36 or 38mm CVK's.

All relevant information to the tune/set up is posted in the YouTube information, however, Justin said he has now changed the main jets from 150's to 210's.

[turn69up]

Thanks guys lots of great info there i bought some dellorto dhla carbies with a jap manifold (the brand eludes me at this hour) but they are the "emission" type, hope fully can just change 1 part to get them to be the "performance" type + need some linkages etc so putting that aside for now (plan to have a few carbie 4age equiped cars) and go with the r1's carbies as i can get some for an ok price and manifold would be really easy to make. Jut one more question i have desided to go the hyperpak route but they want to know if i a 3 or 4 wire dizzy i know what that means but i dont have a dizzy yet and was about to buy just the 3 wire type as its for a big port and would just buy a bp dizzy but was thinking would that exta wire be usefull? As in i wana run a rev limeter an know u need a carbie spesific one but would that extra wire let me run a normal one ie Bee*R