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throttle bodies or carburetors?!!?!?!?
jimbona2 - 27/3/08 at 10:09 AM

okay, this feels like the biggest question of my life, which way do I go, carbs or throttle bodies?

I know throttle bodies are more expensive but offer better maintenance and ease of installation?

carbs being the opposite, cheaper, harder to install.

whats the general opinion as its keeping me up at night!

cheers!

[Edited on 27/3/08 by jimbona2]

Mr Whippy - 27/3/08 at 10:12 AM

How good are you with computers?

I like carbs as their familiar and I can fix them but admit they're no match for an injection system.

jimbona2 - 27/3/08 at 10:15 AM

im a web developer so not bad

Paul TigerB6 - 27/3/08 at 10:17 AM

I'd go for a set of bike throttle bodies myself on the Zetec with a Megasquirt. Weber / Dellorto carbs were a pain to keep in tune so if going carbs it would be the bike carbs route for me, but why not go the whole hog and have the even better TB's

jimbona2 - 27/3/08 at 10:20 AM

whats TB? !! thanks!

Paul TigerB6 - 27/3/08 at 10:23 AM

quote:
Originally posted by jimbona2
whats TB? !! thanks!


Throttle Boddies

02GF74 - 27/3/08 at 10:23 AM

depends on age of engine for SVA emissions test. if post 1995 yoiu need TB and cat.

pre will pass on carbs.

if ^^^ does not apply, then carbs are much cheaper and simpler.

whitestu - 27/3/08 at 10:38 AM

I've gone for carbs due to ease and cost.

No need to plumb in a fuel return etc. Carbs and pump cost £40. Manifold [if it works properly] cost another £20.

Stu

jimbona2 - 27/3/08 at 10:40 AM

do TBs give better performance?

Mr Whippy - 27/3/08 at 10:50 AM

quote:
Originally posted by jimbona2
do TBs give better performance?


Simply…yes, plus the mega squirt thing can be programmed to match that individual engine exactly, something which is not possible to do with carbs. Even be best duel choke Webber setup is inferior for many reasons.

Not that it's stopping me putting duel carbs on my Falcon, why? cos they look awesome



[Edited on 27/3/08 by Mr Whippy]

Schrodinger - 27/3/08 at 10:58 AM

Define better performance?
If you mean more hp or torque then probably not but if you mean useable across the rev range and possibly better fuel ecconomy then you most likely will get that if they are set up correctly for your engine.

jimbona2 - 27/3/08 at 11:46 AM

good question, i was initially thinking about the acceleration to 60mph but thats probably a silly thing to think off...?

Paul TigerB6 - 27/3/08 at 12:14 PM

As mentioned above you will find the driveability improved over carbs. Having driven zetecs with both Dellorto's (my own old Tiger S6), Webers, and bike carbs, I found the bike carbs gave improved driveability over the Webers / Dellorto's. Bike TB's should be a big step up again in terms of driveability.

Peak power figures look great on paper, but in the real world you drive on the torque. The ability to really have full control over the fuel mapping should see you gain much improved torque curves and maybe a little extra power right through the rev range. For this reason alone you should end up with a slightly quicker car which is smoother to drive.

On the downside, start-up costs are higher as mentioned with the extra fuel return, possibly a swirl pot, dearer megasquirt system etc. Also a full rolling road session is likely to be dearer but you will benefit from lower ongoing costs. Do the sums i'd say and see what your preference is. I'd still have to say you should be able to get running on bike TB's considerably cheaper than paying WebCON for a weber carbs / ignition system for which Tiger are about the cheapest.

BenB - 27/3/08 at 01:40 PM

It's simple really

There's nothing wrong with a well set-up pair (or more!) of carbs. However, setting it up can be tricky and often gains in one rpm area will be at the loss of power in other parts of the rev range.

With throttle bodies everything is adjustable and you can iron out any flat areas. It's also easier to adjust and therefore you'll be more inclined to squeeze out the last few Bhp...

At the end of the day badly set-up TBs will be just as bad as badly set-up carbs!! With carbs you have to muck around with jets, needles and choke sizes (and you're always going to run into compromises). With TBs you just adjust the laptop

Nothing wrong with carbs- but I'm still converting to TBs...

jimbona2 - 27/3/08 at 02:14 PM

how much work is involved in bolting the throttle body option together?
any photos of this additional fuel return thingy?

thanks,

Paul TigerB6 - 27/3/08 at 02:22 PM

Have you got the Tiger injection tank or the standard one at all Jim?? Depending on which will depend on how much work is involved. Standard tank could be used to feed a seperate swirl pot in the engine bay via low pressure pump and then having a high pressure pump in the engine bay to feed the TB's. Injection tank will involve fitting a second pipe to the rear and then using a suitable pump to feed the whole system.

jimbona2 - 27/3/08 at 02:28 PM

the fuel tank is from tiger.

Paul TigerB6 - 27/3/08 at 02:45 PM

They do both an injection tank and one designed for carbs. The injection one has a second outlet on the end for the fuel return plus some internal mods i believe. I would assume therefore that you have the single outlet one for carbs.

I think the best option in this case would be to fit a low pressure pump at the rear and run this to a swirl pot (like this) or similar. The 3 outlets on the side are for low pressure feed, high pressure outlet and high pressure return. There's then a breather on top.

From this swirl pot you feed the throttle bodies via a high pressure pump to the fuel rail and then believe you will need a pressure regulator after the rail before returning to the swirl pot. You will probably want a filter in both low pressure and high pressure lines before the fuel pump also.

coozer - 27/3/08 at 04:10 PM

Depends how old the donor engine is, pre 95 will be fine with carbs, but the newer you go the tighter the emissions are the more easier it will get with bodies.

Saying that if I was doing it again I would use throttle bodies with megajolt. Just for the techno factor

Paul TigerB6 - 27/3/08 at 04:37 PM

quote:
Originally posted by coozer
Saying that if I was doing it again I would use throttle bodies with megajolt. Just for the techno factor



Errr you mean MegaSquirt, just for the fueling factor

mark chandler - 27/3/08 at 04:45 PM

No need for a return if you run a swirl pot up front, then the efi is closed circuit but you do need two fuel pumps.

Jenko - 27/3/08 at 04:59 PM

quote:
Originally posted by mark chandler
No need for a return if you run a swirl pot up front, then the efi is closed circuit but you do need two fuel pumps.


My swirl pot has an overflow outlet on the top which has to be routed back to the fuel tank.........So, even if the swirl pot is at the front does it not still need some return back to the fuel tank?......The only time I could see this not being an issue is if you have a one way fuel rail set up and the pump regulates the pressure........

big_wasa - 27/3/08 at 05:23 PM

So what happened to the mondeo efi ?

coozer - 27/3/08 at 05:31 PM

quote:
Originally posted by Paul TigerB6
quote:
Originally posted by coozer
Saying that if I was doing it again I would use throttle bodies with megajolt. Just for the techno factor



Errr you mean MegaSquirt, just for the fueling factor


Sorry my mistake I did indeed mean Megasquirt. It's good for fuelling and spark and believe can determine the boost as well for a turbo engine I'm building

Steve

Paul TigerB6 - 27/3/08 at 05:39 PM

quote:
Originally posted by Jenko

My swirl pot has an overflow outlet on the top which has to be routed back to the fuel tank.........So, even if the swirl pot is at the front does it not still need some return back to the fuel tank?......The only time I could see this not being an issue is if you have a one way fuel rail set up and the pump regulates the pressure........


I have wondered about the top outlet myself as they seem to be marked as either a return or breather (as per here) depending on how you run the system i guess??

Is what Jenko says above the reason it can be used as either???

jimbona2 - 28/3/08 at 04:00 PM

how tricky is this fuel return to setup and is this the only difference? unfortunately i just bolted the fuel pump in, i assume the wrong one for TBs as I got the fuel pump from the original bloke that sold me the build.

stevebubs - 28/3/08 at 05:37 PM

quote:
Originally posted by big_wasa
So what happened to the mondeo efi ?


Ditto - if you're looking for cheapest option, then the standard mondeo system will get you up and running and through SVA...

Paul TigerB6 - 28/3/08 at 05:46 PM

quote:
Originally posted by jimbona2
how tricky is this fuel return to setup and is this the only difference? unfortunately i just bolted the fuel pump in, i assume the wrong one for TBs as I got the fuel pump from the original bloke that sold me the build.


If you run a swirl pot in the engine bay you need the standard pump to feed it so you are fine with it.

Just not 100% sure whether you need to run the top outlet as a return to the main tank in which case its just a second copper fuel line running down the tunnel and then figuring out a way to return the fuel into the tank, or as a breather. It seems to depend on the injection fuel pump you are going to use.

jimbona2 - 30/3/08 at 05:52 PM

hi guys,
i always hear this Megasquirt brand being mentioned, can I ask why? is it the best performer, easiest to install, cheapest??
cheers

Schrodinger - 30/3/08 at 08:20 PM

quote:
Originally posted by jimbona2
hi guys,
i always hear this Megasquirt brand being mentioned, can I ask why? is it the best performer, easiest to install, cheapest??
cheers


Cheapest after market as you buy the bits and solder it together yourself.

As regards the swirl pot the top outlet could be used as a breather on a low presure carb system but not with f.i. high pressure as the pressure from the hp pump will just spew fuel everywhere at low engine speeds surely

[Edited on 30/3/08 by Schrodinger]

mark chandler - 4/4/08 at 08:31 PM

"As regards the swirl pot the top outlet could be used as a breather on a low presure carb system but not with f.i. high pressure as the pressure from the hp pump will just spew fuel everywhere at low engine speeds surely"

Not so, the EFI pump sources and returns its fuel to the swirl pot, as the volumn of fuel is a constant , the swirl pot just becomes a very small fuel tank.

A carb type pressure pump keeps this tank topped up, no return required.

There is no high pressure in the swirl pot, this just exists between the pump and the injection rail, as you drive fuel is consumed by the engine, if you had a perfectly sealed system you would not even need the low pressure pump, its purpose is really to prime the system.

Regards Mark

MikeRJ - 4/4/08 at 10:26 PM

quote:
Originally posted by mark chandler
There is no high pressure in the swirl pot, this just exists between the pump and the injection rail, as you drive fuel is consumed by the engine, if you had a perfectly sealed system you would not even need the low pressure pump, its purpose is really to prime the system.


Right, and this is one reason a return from the swirl pot to the tank is a good idea. without this return, if the swirl pot is empty the low pressure pump won't be able to fill the swirl pot as there is nowhere for the air to go (it will very slowly come out of the injectors when the engine is spun over but it could take a very long time to bleed it all out this way).

The other is that by cycling the fuel between tank and swirl pot it doesn't get a chance to heat up like it would if it's just being pumped between the fuel rail and the swirl pot mounted in a hot engine bay.

jimbona2 - 7/4/08 at 09:41 AM

ok, got a better idea what it all means now, carbs are cheaper but need more maintenance, whereas bike carbs are more expensive but easy to live with, and they can provide more performance by changing the settings through a computer. so in effect, the answer to can bike carbs offer more performance is YES they can.

my only remaining question is what do I need to get a throttle body setup?

i know, that you get/ need the following parts for the carb root but I have no idea what I need for the TBs.

Carb root
==============
2 x twin 45 carbs,
Inlet manifold,
TPS,
Throttle linkage,
ECU,
Wiring Loom,
Trumpets,
Air filters


Throttle Bodies
==============
Throttle bodies (Yamaha R1 or Kawasaki)
ecu
high pressure pump


dont know what else ?

anyone know what you need for TBs?

[Edited on 7/4/08 by jimbona2]

MikeRJ - 7/4/08 at 10:47 AM

quote:
Originally posted by jimbona2
ok, got a better idea what it all means now, carbs are cheaper but need more maintenance, whereas bike carbs are more expensive but easy to live with, and they can provide more performance by changing the settings through a computer.


Not quite, bike carbs are basically the same as any other carbs, but you get one per cylinder and they have quite high flow capabilities. Tuning them is by changing/modifying jets as it is on most other carbs.

For an ECU controlled fuel injection you need throttle bodies which is just a throttle in a housing with space of a fuel injection. Much, much simpler than a carb, and fueling can be adjusted by hooking your computer up to the ECU. However installing and getting started with the set-up is rasther more complex than using carbs.

jimbona2 - 7/4/08 at 03:17 PM

hi,
just had a word with Chester sport cars and they only supply the TB kit with the webcon alpha setting which does not come with any software so it cannot be changed??

so part a) of my question is where can I buy the package I want and b) if you cannot configure the settings yourself to squeeze every last bhp out then can TBs really offer much more performance?

thanks again

[Edited on 7/4/08 by jimbona2]

Paul TigerB6 - 7/4/08 at 04:15 PM

Chester Sportscars dont have a supplier for the MegaSquirt as they do for the MegaJolt so have no choice there.

Not sure who the best supplier is for this but plenty of people on here have one so i'm sure you will soon have a recommended supplier and be able to get a map from someone. These guys do them assembled anyway

jimbona2 - 7/4/08 at 04:25 PM

thanks for this. scholar engines do the pack for £2k ouuchhh.. but i still want it!

MikeRJ - 7/4/08 at 04:49 PM

quote:
Originally posted by jimbona2
b) if you cannot configure the settings yourself to squeeze every last bhp out then can TBs really offer much more performance?


The problem with this is that unless you happen to own a rolling road then you won't be able to squeeze out every last bit of performance. However, I personally wouldn't buy any aftermarket ECU that didn't come with the appropriate software.

If you want a reasonably priced commerical system with some of the best support in the business then get an Emerald ECU.

Paul TigerB6 - 7/4/08 at 06:44 PM

Cheapest way to do it Jim is to buy a MegaSquirt kit and solder it up yourself (i built a simpler megajolt easy enough)

Do a search on here for suppliers (here's one to start with right here )

You will then need a set of throttle bodies from a suitable bike such as the GSXR1000 or similar - i'm sure others more knowledgable will advise suitable sizes but maybe these??)