Throttle Bodies Over Carbs - What Are Peoples Views?

[Andy M1tchell 0]

Ok every body laugh cos I'm a complete numpty on the subject as I have never fitted carbs or throttle bodies to any of my 205's in the past but what are peoples views on running carbs and running throttle bodies.

I have always planned to go down the throttle body route as they are more economical and give out less emissions or is that not true?.

I thought throttle bodies would work better with mapped engine management and fuel injection for a turbo 205 gti but I keep coming across cheap carb set ups for sale and they seem to be more widely available than throttle body set ups and much cheaper so now this is changing my mind!

Will running a turbo with carbs become to expensive with every day use?

 

Help please it would be appreciated

 

thanks

[dazEmad 0]

Not so sure about the emmisions being better with throttle bodies i really struggled to get mine threw the mot. Had to be taken back to the mappers to adjust the fuel to get it threw the mot.

I cant compare to carbs because i have never had them but the throttle bodies do seem to be quite economical and suppose to have lesser issues with having to be adjusted / tuned.

Edited July 8, 2008 by dazEmad

[welshpug 1,621]

Once you get the Management mapped that's it, no more messing about no faffing with cold starts hot starts Bad fuel economy etc (if you get it mapped correctly of course)

 

IMO there is no argument, T/B's and mapped management every time

 

However if you plan on running a turbo you don't need throttle bodies, just a suitable inlet and the Aforementioned Mappable management.

 

carbs AND a turbo?? that's even worse than a 5th injector setup

[Andy M1tchell 0]

carbs AND a turbo?? that's even worse than a 5th injector setup

 

 

Yeh I know lol just a thought as i keep coming across loads of carbs for sale also the renault 5 gt turbo run on carbs!

[pee vee 1]

you can run Throttle bodies and a turbo.. but the mapping needs to be a bit special!

[Andy M1tchell 0]

you can run Throttle bodies and a turbo.. but the mapping needs to be a bit special!

 

 

cheers - yep i know dis!

[monty69 6]

Bodies should be better mpg, carbs need servicing(clean up, float height setting, new needle valves)and then just a case of tweaking the balance occasionally(one screw). The trick to getting ok mpg with carbs is mapd ignition and carbs set up correctly

[Miles 331 1 Cars]

Carb's are cheap for a reason, cr*p and need money spending on them as most need a rebuild and need tuning from time to time, If you have a pressure regulator fail then the engine get's covered in Fuel which is well, not very safe,

I have done a back to back going from Carb's to bodies and gained a extra 13 bhp without anything else, the owner got feb up with the carb;s as it would do something different everyday even after spending allot of money on them, now the bodies are on he's done 3500 miles without any problems, The last engine only managed 2000 miles.

[engine killer 5]

I am currently running a mildly modded Mi205 with tbs and a management. The turner mapped the half throttle a bit lean and the car actually runs less fuel than a stock 8V205 when doing city driving. But of course, for full throttle combat it sprint much faster, fuel also

Edited July 9, 2008 by engine killer

[base-1 17]

Throttle bodies will make your project much easier TBH but I hate when people post threads like this and get bulls*it rumours and poor experience from "the internet" about carbs. Carbs are good, and work really well when they are in good working order and are correctly setup. In this aspect they are exactly the same as bodies - bodies that are falling apart or running a s*it map will not perform properly. Pretty obvious really.

 

Once you get the Management mapped that's it, no more messing about no faffing with cold starts hot starts Bad fuel economy etc (if you get it mapped correctly of course)

 

IMO there is no argument, T/B's and mapped management every time

 

However if you plan on running a turbo you don't need throttle bodies, just a suitable inlet and the Aforementioned Mappable management.

 

carbs AND a turbo?? that's even worse than a 5th injector setup

 

What exactly is wrong with carbs and boost, care to explain? Does boosted air flow through a carburettor different to normal air? No, it doesn't. Also, carbs DO NOT need setting up regularly, or any faffing around when on cold starts if they are setup properly. Do you think everyone who bought Nova Sports or 60s Elans or early 911s etc etc had to take their car in to get serviced every 6 months, including an engine tune? Of course not!

 

The trick to getting ok mpg with carbs is mapd ignition and carbs set up correctly

 

Oh yes! Trouble is people don't, and then tell their friends on the internet that carbs are rubbish

 

Carb's are cheap for a reason, cr*p and need money spending on them as most need a rebuild and need tuning from time to time, If you have a pressure regulator fail then the engine get's covered in Fuel which is well, not very safe,

I have done a back to back going from Carb's to bodies and gained a extra 13 bhp without anything else, the owner got feb up with the carb;s as it would do something different everyday even after spending allot of money on them, now the bodies are on he's done 3500 miles without any problems, The last engine only managed 2000 miles.

They're cheap because they're old and knackered maybe, new carbs aren't cheap! They DO NOT need tuning unless something changes that requires an adjustment, unless by time to time you mean a couple of years? If you have a low pressure pump you don't need a regulator at all, you do need one always on injection and that's just as likely to fail so that turns that argument 180

 

If that engine only lasted 2k miles on carbs and whatever failure was attributed to them, that says alot about the setup, or that there was a problem somewhere. Whichever, not a fair comparison at all!

 

One 911 I worked with was on carbs, running a dizzy too with 12 plugs. I can't remember figures it made, but after the switch to bodies it gained a whole 3bhp and about 10lb.ft - wow, really worth the effort there. Only driveability change was you could now floor it from maybe 2000rpm instead of 3000rpm without it bogging down - worth it? Not really. Shouldn't have got his car setup when it was running carbs I guess, then he would have seen a better gain!

 

Rant over!

[petert 549]

The trick to getting ok mpg with carbs is mapd ignition and carbs set up correctly

 

This applies to both carbs and bodies. Most tuners can't be bothered to map the ignition fully, usually just running with a known 2D dizzy curve, entered into the maps. Unlike AFR tuning, ignition mapping takes time. Time equals dollars. And if you're going to spend the money on mapped ignition, you may as well add the fuel.

Edited July 9, 2008 by petert

[Sandy 189]

I'm largely with Rich really^^^^

 

I set up quite alot of Peugeots with carbs/dizzy, carbs/mapped ignition, TBs/full management.

As had been said, poor set ups are often to blame for the reputation of carbs, but this is also often true of TBs. Obviously everything should be in tip top condition to work properly and well set up by someone that knows what they are doing. The results are usually proportional to the time and knowledge that are applied to the set up.

Anyhow, I prefer TBs/full management because of the fine tuning it allows, but I have been simply astonished by how well some carb set ups work, (John Goodhand's 1.5 8v is brilliant from cold on dizzy/DCOEs! Matt Holley's mapped ignition/DCOE GTi6 runs far better than many TB set ups I've seen too).

But these are the important issues I pay attention to to get good results:

Carbs- Mounted correctly (+/- 7 degrees from horizontal) with good inlet seal, correct fuel delivery/pressure, moderate choice of chokes/pump enrichment. Anything more than a moderate spec engine should get 3D mapped ignition, you can work wonders with it, iron out almost all the vices, good inlet manifold design.

 

TBs- Correctly sized bore TBs, good inlet manifold design (most cast ones are, hmmm, compromised!), sufficient tract length are careful attention to tuning of the tract length and trumpet shape, correctly sized injectors (as close as possible to the smallest you can get away with), injector position (ideally one set in the head, second set further up the tract, switching in on duty and higher loads/speeds). The last point is a far bigger issue to smooth running, easy mapping, good economy and responsiveness than many people credit IMO. On the twin injector set ups I've done, the tracts have remained clean and un-stained, where as injectors mounted in the TBs only will completely colour and even coat the floor of the manifold/port from unmixed puddling fuel, after only a few hours of running, that's enough to convince me; but it shows too in how much compensation is required for throttle transient and cold start. This is one area I think where dyno testing and road use results diverge strongly!

[Matt Holley 11]

As said its all down to the initial set up, I have seen some rough tb set ups at track days that spent most of the day with a lap top on it while I was having fun in my carb powered 205 and that was my old one with a dizzy bolted on, back when I started doing track days they didnt seem like the reliable option at all, these days they are being fitted and set up properly and my view on them has improved.

 

I went for carbs again on the latest 205 as a set came up that had been refurbed and I still see them as being reliable, with the mapped ignition they are fantastic, It starts from cold first time, just give the throttle a few pumps turn it over and its fires up, one blip of the throttle and it ticks over perfectly, the proof is in the pudding so to speak, I have given this car alot of abuse and countless track days and its still running well.

 

If you can afford to go for tbs then go for it, if not dont let people talk you out of carbs, a good set, set up well will give plenty of smiles

Edited July 12, 2008 by matt holley

[Andy M1tchell 0]

Thanx 4 all the input guys it really is well appreciated - yeh I am thinking along the same lines as all you guys just cant make up my mind what is a better option.

The use of throttle bodies will be a lot easier but more expensive to buy but the more economical with fuel than carbs.

But with the use of carbs I was thinking I could get rid of the standard fuel injection and the stupid cold start problems I have encountered numerouse times in the past with my previouse 205 gti's.

Even with my last 205 gti turbo which had a freshly rebuilt engine and all ignition components where changed for new and all breather pipes where cleaned and both the S.A.D and collant temp sensor where changed for new as well as everthing else i had to do cant remeber exactly now as it was 3 yrs ago!

Still it used to start turn over and then stall you had to rev it or giver it some with accelarator as you started it!

Anyway with the use of carbs and mapped ignition I was thinking i could over come the cold start problems ?????

[DanteICE 72]

A friend of mine ran, his old escort 1.3 everyday to work, no matter how long he left the car standing for it would cold start, even in summer. It was old yes, .....and a little knackered. I rigged up an electric water pump and fed it through a sort of swirl pot I suppose you could call it, then he took a diesel glow plug and screwed it in the swirl pot. Before starting he would flick a switch, the eletric water and glow plug would start humming away for about a minute and the engine was nice and warm...instant start. Rather practical and ingenius really. Just a thought for all the cold start suffers.

 

But on the Carbs vs TB's, if your on a budget then carbs, otherwise Throttle bodies, but make sure if your boosting the engine, that the butterfly setup can take the pressure, they make special throttle bodies for turbo engines so that they can take the pressure. I suggest a blow off valve (into the exhaust please) to stop pressure build up, should see better life of turbo at least.

 

Make sure whatever you go with, get it setup right and you'll be happy as larry! I think thats the lesson we've learnt today.

[bales 1]

But on the Carbs vs TB's, if your on a budget then carbs, otherwise Throttle bodies, but make sure if your boosting the engine, that the butterfly setup can take the pressure, they make special throttle bodies for turbo engines so that they can take the pressure. I suggest a blow off valve (into the exhaust please) to stop pressure build up, should see better life of turbo at least.

 

Make sure whatever you go with, get it setup right and you'll be happy as larry! I think thats the lesson we've learnt today.

 

How do you put a blow off valve into the exhaust! and why!

 

I think that the original question is a bit misleading as he is talking about a turbo'd engine not a n/a so it is very different, carbs suck, turbo's blow, standard carbs won't work with a turbo set-up. They are very tricky to get running properly and why would you want to really as you wont hear as much as you will need an enclosed plenum around it.

 

Same with t/b's, theres nothing wrong with having individual inlet trumpets in a plenum but you wouldn't have each one throttled, you would have one large t/b. I'm not saying it can't be done, but FI engines just generally arent desgned in that way as there is no real advantage.

[Sam 4]

I had carbs for ages and going to Throttle Bodies was like a fresh pair of pants after a weeks walking in the brecon beacons. The difference was night and day. Like has already been said, the setup was the key and unfortunately the decent tuners are rarer than hens teeth these days, alot of them talk the talk but do not walk the walk.

[DanteICE 72]

How do you put a blow off valve into the exhaust! and why!

 

I think that the original question is a bit misleading as he is talking about a turbo'd engine not a n/a so it is very different, carbs suck, turbo's blow, standard carbs won't work with a turbo set-up. They are very tricky to get running properly and why would you want to really as you wont hear as much as you will need an enclosed plenum around it.

 

Same with t/b's, theres nothing wrong with having individual inlet trumpets in a plenum but you wouldn't have each one throttled, you would have one large t/b. I'm not saying it can't be done, but FI engines just generally arent desgned in that way as there is no real advantage.

 

 

To start with a blow-off valve releases pressure, which is forced upon the throttle body/bodies by the turbo, which is still spinning madly, when the driver pulls off the throttle. This pressure between the throttle body and turbo builds up and is not good for either TB or Turbo, and that squealing chicken you hear from turbo cars is actually this pressure forcing the turbines of the turbo to spin down rapidly and even change direction. So a blow-off valve opens up when pressure is built up between the turbo and throttle body and releases this pressure, mainly to reduce turbo lag, but it help to extend the life of the turbo and even the TB. Thats the stupid boy racer hissing sound you get when the drivers pulls off the throttle for a gear change for instance. So instead of releasing the gases out of the blow-off valve into the atmosphere, you can divert it either back into the intake or into the exhaust. By doing this you don't get the stupid hiss and people don't know you've got a great big turbo under the bonnet!

 

AND

 

Many old turbo cars used carbs, its not hard at all! Probably easier!

 

Sometimes getting an indication of what works and what doesn't by what the F1 people do, isn't always perfect, as they are majorly restricted by the rules of the FIA. Like turbos (BANNED) and DSC (BANNED). I would also be very surprised if they didn't use multiple throttlebodies ie, 1 per cylinder, as it closes the gap from fresh air to intake so fast throttle response, same reason Reylands Escort Cosworth (Turbo) has throttle bodies in the inlet plenum and not just one great big one, throttle response. Maybe I missed the point of what you were saying though, I can do that sometimes!

[bales 1]

To start with a blow-off valve releases pressure, which is forced upon the throttle body/bodies by the turbo, which is still spinning madly, when the driver pulls off the throttle. This pressure between the throttle body and turbo builds up and is not good for either TB or Turbo, and that squealing chicken you hear from turbo cars is actually this pressure forcing the turbines of the turbo to spin down rapidly and even change direction. So a blow-off valve opens up when pressure is built up between the turbo and throttle body and releases this pressure, mainly to reduce turbo lag, but it help to extend the life of the turbo and even the TB. Thats the stupid boy racer hissing sound you get when the drivers pulls off the throttle for a gear change for instance. So instead of releasing the gases out of the blow-off valve into the atmosphere, you can divert it either back into the intake or into the exhaust. By doing this you don't get the stupid hiss and people don't know you've got a great big turbo under the bonnet!

 

AND

 

Many old turbo cars used carbs, its not hard at all! Probably easier!

 

Sometimes getting an indication of what works and what doesn't by what the F1 people do, isn't always perfect, as they are majorly restricted by the rules of the FIA. Like turbos (BANNED) and DSC (BANNED). I would also be very surprised if they didn't use multiple throttlebodies ie, 1 per cylinder, as it closes the gap from fresh air to intake so fast throttle response, same reason Reylands Escort Cosworth (Turbo) has throttle bodies in the inlet plenum and not just one great big one, throttle response. Maybe I missed the point of what you were saying though, I can do that sometimes!

 

Why would you vent presssure into the exhaust? its always either back into the intake or to atmosphere, i run my car without a dump valve as i prefer the chatter and tbh for how often it is used i'm not worried about any extra strain on the compressor wheel.

 

I am genuinely intrigued to the venting of inlet pressure into the exhaust though, how do you set up an arrangement like that, surely the fact that the exhaust is always in positive pressure must make it awkward to do that, you sure you arent getting confused with a wastegate??

 

My point was really that itb's and turbo's generally aren't used, not saying it cant be done, but juts generally isnt.

[jackherer 543]

My point was really that itb's and turbo's generally aren't used, not saying it cant be done, but juts generally isnt.

 

Only due to cost IMO, Nissan Skylines and Pulsars have six/four throttles I believe.

[welshpug 1,621]

Pulsars do Skylines don't, Skylines actually only have a single throttle the same size as a gti6

 

Always down to cost and packaging at the end of the day.

[jackherer 543]

Pulsars do Skylines don't, Skylines actually only have a single throttle the same size as a gti6

 

Well, a mates R32 GTR has factory looking ITBs but it has been tweaked to 550bhp so I checked and you're wrong, all GTR's (R32,33 and 34) have six individual TBs.

[GLPoomobile 958]

Well I never! All these years I assumed the RB26DETT used a single throttle body and that is was only the Pulsar that used ITBs. But you are indeed right, as a quick google seems to prove that certainly most of them did seem to use ITBs.

[welshpug 1,621]

cool didn't realise the GTR was that much different!

[base-1 17]

I think that the original question is a bit misleading as he is talking about a turbo'd engine not a n/a so it is very different, carbs suck, turbo's blow, standard carbs won't work with a turbo set-up.

 

Not true, carbs don't do anything, same as throttle bodies. The engine sucks through the carbs/bodies, airflow result is similar to a charger blowing through.

 

Kieran's right, GTR engines do have individual throttles. Go Nissan!