webbers on my gti ?

20th February 2013, 16:31

i have got a gti what has newman cams - port and polish -remaped and unlocked - full pug sport exhaust i have been offered some twin webber 40 carbs just wondering what the gains will be and how it will sound also how hard are they to fit and could they just run on my current map for now ?

thanks josh

20th February 2013, 16:34

You will have to say goodbye to mpg, a mate had some on his capri and all it did was throw fuel in and didn't make much difference.

Save up and get some itb's and a standalone ecu.

And I highly doubt you will just be able to put webers on and expect it to run

20th February 2013, 16:38

to be fair mate my mpg is shit what did they sound like ? and i have looked in to it but im only 18 and dont have that kind of money the lad who offerd me said that it would run but im not sure

20th February 2013, 16:45

Haha I'm ony 19 and have a turbo'd saxo, just have to save

Yeah you could make them to run but you will need a manifold making to mount the webbers on, a standalone ecu, somehow make the sensors fit and work with the webbers, differnt throttle cables, low pressure fuel pump, regulator for fuel, different filters.

A lot of work for what you will gain but the do sound pretty good, and the mpg you will be getting now will be a whole lot better than what you will see with twin 40's

20th February 2013, 16:46

With enough fiddling a carb setup could be made to work on any petrol engine. Why you would want to I don't know. Carb's are always a compromise in setup. A top end optimised setup will be horrid to drive at the low end. A low/mid range optimised setup will be restricted at the top end. Setting a carbed engine up properly is a bit of a dying art form, as itb's + an ecu can be made to work much better across the whole engine power band.

Also, you would have to remove and blank off all of the injection setup as it would no longer be required.

20th February 2013, 16:53

its got the manifold on it does it deffinetly need standalone ? to be fair as long as i dont loose power im not too fussed just i heard a gti on throttle bodies and it sounded good

and i have my vtr what im scraping this week then my other vtr which im turboing i nearly have all the kit just waiting for my manifold but have time going to sell it anyway and bought a 106 van with gti engine i will upload a pic later

so probably better waiting till i sell the vtr then get throttle bodies what power do you rekon i will get ?

20th February 2013, 16:58

No it does not need stand alone ECU.

The original ECU can still operate the Ignition if you rig up the original TPS.

20th February 2013, 17:03

ok thanks mate i will have a word with the lad and see what he knows about them

what site do i use to upload a picture by the way ?

21st February 2013, 14:29

Search for the threads on this.

Can you do it? Yes... Is it a backwards step in performance turnings. Yes....

Save your cash.

21st February 2013, 15:28

I wouldn't say it's a backwards step, it's just that Webers are notorious for going out of tune really quickly.

Performance tends to be better when you feed an engine large fuel droplets, rather than a fine mist as the fuel takes longer to burn so you've still got burning fuel pushing the piston down for longer.

21st February 2013, 16:35

What? What happens when the drops are so large that it doesn't all burn before the piston reachs bdc and starts coming back up? It pushes the still burning fuel mix down the exhaust, meaning wasted power. A fuel in a fine mist will burn much quicker and consequently a bigger bang will be produced each time with no burning fuel going down the exhaust. Whether the con rods and piston tops can take the increased forces is a different question.

21st February 2013, 16:42

Quote:

Originally Posted by mechsman

What? What happens when the drops are so large that it doesn't all burn before the piston reachs bdc and starts coming back up? It pushes the still burning fuel mix down the exhaust, meaning wasted power. A fuel in a fine mist will burn much quicker and consequently a bigger bang will be produced each time with no burning fuel going down the exhaust. Whether the con rods and piston tops can take the increased forces is a different question.

you're not going to bend conrods unless you're revving the tits off it or fitting forced induction. the gains are never going to be that much.

If the drops are that large, you've got a shit carb or you don't know how to set a carb up

Fuel injected 1275 minis have way less HP than ones fitted with webers or reece fish carb down to fuel droplet size.

21st February 2013, 17:01

Quote:

Originally Posted by MartinObviously

I wouldn't say it's a backwards step, it's just that Webers are notorious for going out of tune really quickly.

Performance tends to be better when you feed an engine large fuel droplets, rather than a fine mist as the fuel takes longer to burn so you've still got burning fuel pushing the piston down for longer.

er!

Webers are about four steps back compared to an injection and ecu controlled setup. Save up for throttle bodies or dont bother.

atomised fuel is better than big droplets too! Its why injectors were invented

21st February 2013, 17:07

Quote:

Originally Posted by KamRacing

er!

Webers are about four steps back compared to an injection and ecu controlled setup. Save up for throttle bodies or dont bother.

atomised fuel is better than big droplets too! Its why injectors were invented

you can't say that!

emissions are the main reason behind EFI, plus they are more reliable and controllable.

After catalytic converters became a requirement, nearly all cars switched to EFI because carbs are so unreliable.

with correctly matched carbs (not necessarily over-rated webers) you can get the same performance as ITB's as long as you have plenty of time to invest setting them up all the time.

ITB and ECU is the easy way out because it requires the least work for a good gain.

21st February 2013, 17:20

Quote:

Originally Posted by MartinObviously

you can't say that!

emissions are the main reason behind EFI, plus they are more reliable and controllable.

After catalytic converters became a requirement, nearly all cars switched to EFI because carbs are so unreliable.

with correctly matched carbs (not necessarily over-rated webers) you can get the same performance as ITB's as long as you have plenty of time to invest setting them up all the time.

ITB and ECU is the easy way out because it requires the least work for a good gain.

Don't need to give my opinion, yours says it all...

Read back through what you have said about carbs,
Why on earth you'd choose them over a decent fuel injected setup is beyond me..

Surely reliability is a large part of "performance"?? As you can't have performance without reliability...

21st February 2013, 17:20

I'm being a little generalistic

Seriously with throttlebodies you get better power throughout the rev range. I've never seen a tb'ed car trumped by carbs even if peak figures are the same, the fuel injected car will be faster and easier to drive.

21st February 2013, 17:27

Quote:

Originally Posted by dannygti

Don't need to give my opinion, yours says it all...

Read back through what you have said about carbs,
Why on earth you'd choose them over a decent fuel injected setup is beyond me..

Surely reliability is a large part of "performance"?? As you can't have performance without reliability...

you can if you're on a budget!

Perfomance
reliability
cheap

chose two!

Quote:

Originally Posted by KamRacing

I'm being a little generalistic

Seriously with throttlebodies you get better power throughout the rev range. I've never seen a tb'ed car trumped by carbs even if peak figures are the same, the fuel injected car will be faster and easier to drive.

I know cos ITB's can be set up for the whole range. like you can run a WOT map and an economy map

Optimal fuelling for the whole range, can't do that with carbs.

21st February 2013, 17:41

Quote:

Originally Posted by MartinObviously

you're not going to bend conrods unless you're revving the tits off it or fitting forced induction. the gains are never going to be that much.

If the drops are that large, you've got a shit carb or you don't know how to set a carb up

Fuel injected 1275 minis have way less HP than ones fitted with webers or reece fish carb down to fuel droplet size.

Erm, a much bigger bang (due to faster fuel burn) in the combustion chamber, even in a slow revving engine can still bend the con rods chap. Anyway, my point about shoving the still burning fuel mix down the exhaust still stands.

EFi was fitted to cars with catalytic convertors because cats can't cope with an over rich fuel mixture (that might still be burning when it gets there). Rich fuel mixtures kill cats in short order. Most carbed setups were set up slightly rich for engine safety purposes, as trying to squeeze out that last bit of power by leaning out the mixture to stoichiometric gives a much smaller safety margin for the carb to work in before the mixture goes over lean and starts burning the valves etc.

You can't really compare the fuel injected mini's to the carbed ones as the early EFI setups hadn't had nearly as much development as carb setups at that point, nor were the old engines designed with EFI setups in mind. To see what x number of years of development can do for a technology, you only have to look at the amount of power a small engine on EFI can produce today e.g. ford 1.0l ecoboost engine.

Like i said earlier, carbed cars setup to be driven at full chat will be compromised low down. Setups for optimimum low down/mid range will be compromised at the top end.

21st February 2013, 19:30

Quote:

Originally Posted by mechsman

Erm, a much bigger bang (due to faster fuel burn) in the combustion chamber, even in a slow revving engine can still bend the con rods chap. Anyway, my point about shoving the still burning fuel mix down the exhaust still stands.

EFi was fitted to cars with catalytic convertors because cats can't cope with an over rich fuel mixture (that might still be burning when it gets there). Rich fuel mixtures kill cats in short order. Most carbed setups were set up slightly rich for engine safety purposes, as trying to squeeze out that last bit of power by leaning out the mixture to stoichiometric gives a much smaller safety margin for the carb to work in before the mixture goes over lean and starts burning the valves etc.

You can't really compare the fuel injected mini's to the carbed ones as the early EFI setups hadn't had nearly as much development as carb setups at that point, nor were the old engines designed with EFI setups in mind. To see what x number of years of development can do for a technology, you only have to look at the amount of power a small engine on EFI can produce today e.g. ford 1.0l ecoboost engine.

Like i said earlier, carbed cars setup to be driven at full chat will be compromised low down. Setups for optimimum low down/mid range will be compromised at the top end.

Bro, ever heard of an air pump? it pumps fresh air into the exhaust to burn off excess fuel from a rich mixture to heat the cat up and not destroy it

106 GTI has one

anyways, common on older US carbureted (US spelling for effect) cars

just so you know.

You might find this interesting:

The hillman imp, in racing spec (some good old machining and tweaking) has a 1.0 engine. it's 110HP +

It can hold 10,000rpm for 15 minutes with no damage - this was in the 1960's!

Ecoboost engine is what, 100-125hp? WITH a turbo on top and it would probably explode at 10,000rpm

15HP doesn't sound like progress to me in over 50 years. I'm not having a go, but I'm telling you car manufacturers are having us on! Deliberately not making progress I think.

21st February 2013, 19:49

You talk some shite lol.. You obviously force fed this miss-information from an early age..

For the OP, yes it can be done, yes it will sound great, yes it will give you some gains, is it worth it for the money? Only you can decide that.. Would I do it? No as I believe it will give you problems when it comes to MOT time and once you have finished faffing about you might aswell have bought a second hand ITB setup.

21st February 2013, 19:49

You talk some shite lol.. You obviously force fed this miss-information from an early age..

For the OP, yes it can be done, yes it will sound great, yes it will give you some gains, is it worth it for the money? Only you can decide that.. Would I do it? No as I believe it will give you problems when it comes to MOT time and once you have finished faffing about you might aswell have bought a second hand ITB setup.

21st February 2013, 19:53

The developments now are more about efficiency relating to power instead of outright max BHP and torque figures.

Hence why people are switching to smaller CC turbo engines as economy is becoming ever more apparent in what sells a car (along with all the tax bollocks)

You can get much more power out of many modern day engines with a simple ecu tweak (thats right they are set up for the everyday road goer as opposed to a race engine)

21st February 2013, 20:04

Quote:

Originally Posted by Ryan

The developments now are more about efficiency relating to power instead of outright max BHP and torque figures.

Hence why people are switching to smaller CC turbo engines as economy is becoming ever more apparent in what sells a car (along with all the tax bollocks)

You can get much more power out of many modern day engines with a simple ecu tweak (thats right they are set up for the everyday road goer as opposed to a race engine)

they are deliberately de-tuned. it actually reduces mpg as well.

remaps often see increases in mpg

They're de-tuned to last longer against n00bs who don't maintain their cars.

21st February 2013, 20:08

In the modern era everything is about protecting ones assets.

If a few cars blow engines it can damage a car instantly thus costing a company millions instantly.

Lets also not get into the current 'claim' culture.

But anyway back on topic... When you can get a set of throttle bodies either modified bike bodies or used Jenveys for example i see no reason to go for a backwards step and fit carbs.

21st February 2013, 20:10

Quote:

Originally Posted by Ryan

In the modern era everything is about protecting ones assets.

If a few cars blow engines it can damage a car instantly thus costing a company millions instantly.

Lets also not get into the current 'claim' culture.

But anyway back on topic... When you can get a set of throttle bodies either modified bike bodies or used Jenveys for example i see no reason to go for a backwards step and fit carbs.

I can, it's cheap.