I started writing this out as a reply in another thread but by the time I finished and read it back it was totally off topic and it just made more sense to start its own thread and maybe get a discussion on the go about it...

Some thing I've noticed tho is that the more results I see the less worthwhile bike carbs seems to be, on these 16v's at least. The difference between a standard afh with filter decat and system seems to be nominal when compared to standard afh with bike carbs, decat and system.

Even higher up the spec there seems to be very little gains for the outlay. Mine and Briscoes 1.6 16v's only had 16bhp between them on the same rollers on the same day. As well as the bike carbs his setup had a 4-2-1, cams and I believe head work and verniers over mine. For the cost of parts and setting up people only seem to be getting a handful of peak bhp for their coinage from the carbs, the same kind of gains that can be had for a lot less in the form of a poloace chip. Maybe its the primitive ignition set up's being used not allowing the whole package to reach its full potential? the ignition curves in the mk2 dizzy's are set for totally different engines, even played with dizzy's are still a big step back from the mapped ecu's that normally plot the ignition curve on these engines. Maybe its the carbs themselves or just a mixture of the two, but looking at lupo's with similar set up's to dans but running itb's and aftermarket management making around 180bhp it becomes pretty obvious what's holding it back.

In the past bike carbs just seemed a means to get 16v's running in early polo's but we're at a point now where people with 6n 16v's are wacking bike carbs and mk2 ignitions on but would this money not be better spent on a decent induction kit and a chip?

Thoughts? opinions?

Sorry to use your car as an example Dan but it was the best comparison I could think of, and not trying to start a "bike carbs are gay" thread, just thought that it was worth a discussion seems as its becoming such a popular route to take

Vw designed that engine as a whole package, so the cams, manifold, ignition and inlet etc are matched and work well, if you start changing only a few of those components then you need to chose them carfeully and find out exactly what works.

I think your probably right about the dizzy, its the reason i never put a saab/golf kr dizzy on my hk engine instead just converted the original to electric ignition.

Theres alot to the health of an enigne in its history though so maybe you just have a better engine to start with?

Before and after graphs of enigne mods are whats needed!

The case of running a 16v on standerd injection ..

Just cutting away the imobiliser and stuff you dont need ??

Seems alot cheaper as i can get a engine for 150 with loom and ecu and then spend the money i would of spent on carbs on a clutch, headgasket and waterpump and plugs ..

How hard is the loom to adapt guy ?

Well I struggle to wire in my amp without blowing it up and I managed it

Need to keep the immobiliser and anything else needed to run the engine on a basic loom using the 6n fusebox, fuck everything else off. I always planned to sit down with a haynes and work out how to wire it in to the early fuse box properly but now I'm going aftermarket management I have no need to do it

Before and after graphs would be a good idea although probably not a lot of people will have them, especially in earlier cars where the carbs were fitted along with the engine conversion. Probably the best to hope for are graphs from both sides of the fence so to speak

Well I struggle to wire in my amp without blowing it up and I managed it

Need to keep the immobiliser and anything else needed to run the engine on a basic loom using the 6n fusebox, fuck everything else off. I always planned to sit down with a haynes and work out how to wire it in to the early fuse box properly but now I'm going aftermarket management I have no need to do it

Before and after graphs would be a good idea although probably not a lot of people will have them, especially in earlier cars where the carbs were fitted along with the engine conversion. Probably the best to hope for are graphs from both sides of the fence so to speak

You mentioned aftermarket management, are you going tb's or megajolt with carbs?

I ask because it cant be too hard to just use the 16v ecu for the ignition only, i did it with a gt a while ago when that was running bike carbs. Someone must have done it on here?

I was going itb's with omex management but aiming for boost now instead

I agree with shaun here, its all about how well the engine is.

Typicaly 2 stock GTs on a 1/4mile usually end up with someone winning by quite far.

After taking 4 relativly standard GTs up the strip they all drove differently and they all achived different times, some by a whole second.

I personaly loved bike carbing my blue GT, It was a Super budget set up, lots of things where free or very cheap, I even ran it on the standard engine ignition, the engine orginaly was shite and slow, wacking some bike carbs on and advancing the timing made it 10times more fun, probably gained about a second at the 1/4 mile too, Oh and the noise is pure win, I dont think i would ever do a properly set up bike carb conversion, for £300 Id probably have gianed 5bhp

Edited 22 February, 201214 yr by mattpolo5491

they are worth it for the noise. scares chavs when you boot it thats what matters

they are worth it for the noise. scares chavs when you boot it thats what matters

:badgrin:

I didnt get that with my GT, I just got that wierd Finger slap thing? You know where they flick the hand.

brap.

hahah

To be honest, bike carbs are a pretty easy simple mod.

Getting them running right is another thing, but bodies is kinda the same with injectors and mapping and such.

theres getting them running right, and getting them running right anally. eh mr harris lol

I'm not even allowed to comment about engines hahahaha.

People forget the variance of engines.

When I did karting, we bought 3 brand new engines, each serial number after each other & were all totally different to use!

Imagine the tolerance of car engines, let alone ones 10+ years old with different histories

what jets are you changing today rolf? i think you should go for 146.5 and drop the needles 0.8mm. will get an afr rreading of 13.m.i.n.t

Hahaaaaa mate my car runs 0.2 AFR leaner at idle outside my house than at the traffic lights down the road

this is an interesting read,

and the whole reason i come on here.

i have just purchased my dizzy ignition system, from this very forum. and although it is only to get the car running, and usable. i fully intend to fit megajolt, or similar to map the igniton.

only by doing this can you truely unleash the potential of having the cylinders independantly fed from the carbs. in theory this should also lead to a more economical and healthy engine.

megajolt is in my eyes a cheap upgrade for a sizeable difference in the way the engine performs.

But yeah.

Carbs are a compromise.

Using a mk2 mech dizzy off a 1.3 8v in a modified like 1.4 16v isn't really gonna be perfect is it haha?

But it's like mapping, people map aggressively, people map tame and progressive or powerful low down and tail off faster etc.

hahaha. saving fuel at home like a bosss. its so your ready at the lights to race lambos yo!

Call Aldon automotive.

They are bringing out a box which is mappable ignition using the hall sender in a dizzy, including a rev limiter, immobiliser and 3d mappable ignition.

Apparantaly expected to be around £150 when i asked them last month.

Seems much easier

not having driven a bike carbed afh i cant say - but maybe it is the budget way to a 16v.

However, top end bhp numbers are rarely the whole picture. How responsive and how usable is the power is through the rev range.

a dyno of your power out put is only usable for one thing - to bench mark your current set up against your improved set up later.

I'm guessing aftermarket ecu is going to make a injection afh more than twice the conversion cost of the bike carbed set up.

A bike carbed set up also seems a lot easier to do.

I'm doing the whole car for next to nothing, so its probably the only option to me at present.

Those lupo's with 180bhp are they 1.4's or have they have conversions to 1.6 and what sort of cash for the rest of the conversion?

I've diy'd turbo and supercharger kits before on other cars and its rarely ass cheap as I planned.

To be fair, Nick's probably one of the few that's actually gone to town on properly setting up a set of bike carbs - and even then they're going to be a compromise over a full EFI system; given that it's difficult to change the fuelling at one speed/load point without influencing another.

So I reckon it's a combination of factors:

1. Bike carb conversions are rarely setup properly, if at all.

2. Ignition systems used are often far from optimal.

3. Carbs are incapable of providing perfectly ideal fuelling for all conditions when compared to an EFI setup.

With mappable ignition on a properly setup set of bike carbs I reckon you'd see more power than on stock EFI, but ITBs on EFI fully mapped might see a slight increase (a few percent) on that - with most of the real gains being in partial throttle driveability and economy without melting pistons. My old man's Jensen motor gained only 2% power by going from carb to EFI, and both were setup on an engine dyno so well optimised. However, the EFI setup netted a 50% increase in fuel economy.

I think there's plenty of evidence around now to suggest that if you're going to leave an AFH fairly stock (exhaust, 4-branch and air filter) then for a budget build the stock EFI is better than a set of bike carbs. If you throw a set of cams into the equation I suspect that bike carbs would win unless you know where to remap the stock EFI cheaply.

It cost me at least £300 in the end to bike carb mine, and it was worth every penny. The noise, throttle response, perfect. I'm not even interested in comparing it ton anything else, it just makes me happy blatting it on a country road. I just wish I had more GRIP!

It cost me at least £300 in the end to bike carb mine, and it was worth every penny. The noise, throttle response, perfect. I'm not even interested in comparing it ton anything else, it just makes me happy blatting it on a country road. I just wish I had more GRIP!

tyres boi, tyres.. you wouldnt believe the difference a set of contisports made to my mk2

It cost me at least £300 in the end to bike carb mine, and it was worth every penny. The noise, throttle response, perfect. I'm not even interested in comparing it ton anything else, it just makes me happy blatting it on a country road. I just wish I had more GRIP!

You shouldnt be having grip issues with an afh

A properly setup ignition is severly underated...