carbie 4age

[mike-sj4age]

what is the down side of converting my 20v 4age from injection to carburetored

[iOnic]

http://www.tuning.wanadoo.co.uk/carbure ... ection.htm

Why are you thinking of doing it?

[shihad]

the cost for little gain or possibly a step backwards

[Dell'Orto]

Yep, will set you back easily $1k for the carbs alone.

[NZ_AE86]

what is the down side of converting my 20v 4age from injection to carburetored

Maybe you should be asking what would be the advantage?

Fuel injection is far more precise then a couple of carbs.

Many people may tell you that you'll get more power with carbs - how?
This is a very old idea that dates back to times when aftermarket ecus were too expensive; so if you did serious modifications to your engine carbs were the cheapest way of getting around this.

Why are you thinking of doing this?

[mike-sj4age]

I have been told that for a newbie setting up an injection system is much harder than carbed and also its easyer to add a turbo with carbs..... ?

[Alex B]

I'd disagree with both of those points. EFI on a 4A-GE is not exactly complex stuffs.

Hell of alot easier/ more tuneable to work with a turbo with EFI too.

[NZ_AE86]

A carb'd 4age is much more complex to turbocharge.

You should do whatever you like as it is your car but I would not put carbs on a 4age.
The EFI is already fitted to your car, injectors, fuel system, sensors etc so by changing the ecu to a wire in LINK or similar you will be able to do what ever you like to your engine!

[iOnic]

I asked why he's thinking of it because he may not necessarily have a choice (race class regs?). Tthere are advantages to using carbs if you have the money and know what you're doing.

For the average street 4AGE it's probably a big step backward but for a race prepped version it wouldn't be the worst idea out there...

[matt dunn]

I asked why he's thinking of it because he may not necessarily have a choice (race class regs?). Tthere are advantages to using carbs if you have the money and know what you're doing.

For the average street 4AGE it's probably a big step backward but for a race prepped version it wouldn't be the worst idea out there...

What would those advantages be? As I cant think of one reason why a Carb'd 4AGE would be any better than an EFI 4AGE, Especially a race motor.

Maybe in the old days when 2TGE's has air flow meter's with bore sizes so small you can hardly fit a golf ball in them,
But the rest of the time there's no advantage on carbs,

On a Good day with the right jest to suit the day,
Side draughts can make as much power as injection,
the other 99% of the time they are no where near as good.

[iOnic]

What would those advantages be? As I cant think of one reason why a Carb'd 4AGE would be any better than an EFI 4AGE, Especially a race motor

The main advantage is the simplicity of the setup and that brings several more advantages with it.

Better throttle response, less weight, less points of failure, more reliability (no huge wiring networks to potentially fail, no high pressure fuel), hundreds of sensors each with varying limits and restrictions are instantly removed, easy to tune, easy to work on etc etc etc

Maybe in the old days when 2TGE's has air flow meter's with bore sizes so small you can hardly fit a golf ball in them,
But the rest of the time there's no advantage on carbs,

On a Good day with the right jest to suit the day,
Side draughts can make as much power as injection,
the other 99% of the time they are no where near as good.

Carb technology has come a long way since the old days. Modern carb technology (eg Keihin FCR Carbs) rivals even the best EFI setups in most aspects.

On the NZV8 race engines we remove the EFI gear and install Carby gear (regulations) and when unrestricted they make just as much power as the Aussie touring cars (~475kw) with better throttle response and far better reliability - it's not uncommon to use a single unopened engine for an entire season here. Sadly because of NZ regs they're limited to 6400rpm and 240km/h instead of the Aussie 7500rpm and 300+. And no, we don't have to tune them for each day It's quite rare for them to be re-jetted. The car always starts first pop everytime and runs strong. Unless you looked under the bonnet you wouldn't even know it was Carby.

But as I said before, for a street car it's a big step backward (even more-so if you plan on going turbo). In a race motor "it wouldn't be the worst idea out there..."

[sergei]

Carb technology? Are you on drugs?
It is the same as it has been 50 years ago.

Ultimately carbs work off venturi effect. Venturi effect requires restriction.
Carbs are restrictions.
Accelerator pumps? Extremely inaccurate.
Can't really have precision with carburettor. There is no temperature or pressure compensation. Carbs are nice fuel heaters (another uncontrollable variable). Part of fuel is evaporated and part of it dripping off the walls, just going through combustion and spat out of exhaust.

You are saying carb is simple? A lot simpler than EFI? I say opposite.
very "simple" indeed:



Try pulling one apart, and count how many individual parts you have. With EFI all you need is 2 temp sensor, crank position sensor, pressure and or flow meter, injectors, etc, all discrete and easy replaceable items. EFI is a lot more reliable. There are cars with 500k and EFI (apart from fuel filter, and perhaps fuel pump) has never been touched. I can say this about carbs, I have seen carbed cars with really low kms that needed carb adjustment, and what about shit gunking up all the time and stop functioning properly?

Try running a carb in boosted situation. Total nightmare.

[iOnic]

Not here for an argument at all. I've simply posted what I've found with my real world experience with them - whether you like/believe it or not is your business and doesn't bother me in the least. I also don't need you to tell me how Carb's work. It's my job to know how they work and fix them when they don't and it's what I'm trained to do.....You can refute common knowledge all you want but sadly the only person that cares is you - it's common knowledge for a reason. Just out of curiosity, are you a mechanic or have any formal training in the field?

[Mr Revhead]

On the NZV8 race engines we remove the EFI gear and install Carby gear (regulations) and when unrestricted they make just as much power as the Aussie touring cars (~475kw) with better throttle response and far better reliability

Are you sure about that? Figures I have heard for NZV8s are around 400sh hp. A lot less than the 6-650 for an aussie V8.

And reliability.... well, not really applicable to having carbs or EFI....

[iOnic]

Yep I'm certain. When the engine was first built it was run up on the dyno with no rpm restriction. Real world figures are different because of the imposed low rev limit and to a lesser extent the gearing from the 4 speed gearbox. PM me if you'd like to know more about them. Not too keen to post up too much info on them out in the open for obvious reasons.

[Mr Revhead]

What do you think the power/torque curves would look like laid over a V8SC one then?
Or even the same engine with a well setup EFI system?

In a race car when you don't need to worry so much about low rev performance and various other things carb's won't be a disadvantage, but the best they can do, is be just as good as a EFI set up in certain applications.

If race regs are not applicable, then there is not really a lot of pro's to a carb set up once you get past the "cool" factor

Anyway, as Matt asked, what are the advantages?

[iOnic]

In a race car when you don't need to worry so much about low rev performance and various other things carb's won't be a disadvantage, but the best they can do, is be just as good as a EFI set up in certain applications

This is exactly what I'm getting at. If you're building a race car then there's no reason a carb setup can't be just as good as an EFI set up.

I never said carbs better and I never will nor am I saying that EFI is better - I'm not stupid There are pro's and cons to both setups and they've all been listed already. Application is the main deciding factor - which is why I was asking the guy why he was thinking of doing it...

[Mr Revhead]

Actually to be more accurate I should have said:
In a race car when you don't need to worry so much about low rev performance and various other things carb's won't nessicarily be a disadvantage

[iOnic]

I like that

[matt dunn]

On the NZV8 we don't have to tune them for each day It's quite rare for them to be re-jetted. The car always starts first pop everytime and runs strong. Unless you looked under the bonnet you wouldn't even know it was Carby.

Sorry but that is 100% crap, guaranteed.
Who are you taliking about, one of the good teams,
or one of those who struggle at the back cause they dont kame the necessary changes.

I too do a bit with one of the NZV8 guys,

and dad worked on Kayne Scott's team for the last two seasons,

And I have sat in the pit lane and seen them,

It's not uncommon for them to change the jets a few times in the first practise sessions and during qualifying, and again if the weather changes.

That's why they run dual wideband sensors and Motec data logging.