idiots TB question

[lofty]

right,

16vs/williams run off one large TB,

base injected models run off small ones,

how about (if you could form the manifolds) running four or a pair off TBs off a a base model car, the TBs could be cheaply sourced it would just be tricky getting the manifolds made but im sure somthing similar could be modified to fit, and of coure setting it all up with the ECU?

is this a stupid idea?

 

[Pysco]

I dont know what size the TBs off the smaller cars engined cars are, but assuming you could get the manifold made-up I expect they would be too big. ie too big a change in airflow for small changes in throttle angle, particualy if you had 4. It may be possible, you would almost certainly need a mapple ECU like the Emerald M3D though.

Capt. and BenR may be able to help more.

 

[Captain Slarty]

the idea has been done before..

if you can get 4 tbs at a bout 30-44 mm and make a manifodl, then yes, it could be done, you would still need to fit the injectors.. and as Si says, a moddable ecu..

J.

 

[lofty]

lots of money then? Ben was talking about having 4 (i think) 30mm TBs,

re-mappable ECUs are big money arent they? £1k+?

the manifolds im thinking using something else, and getting an engineer mate to fiddle (bodge) it

still stipid idea?

 

[BRUN]

lofty remappable ECUs are about £400, Lumenition make em, Nick Hill uses em an he can map em too

 

[Pysco]

The ones Ben was talking about are 30mm thick, 45mm chokes made by Jenvey Dynamics. Mappable ECUs are about £400-500+, the Emerald M3D EMS is very good, designed by Dave Walker the CCC guru.

You need to find out what size chokes the TBs your thinking of using have, if there much bigger than 45mm itll be a b**ch to map, youll loose low down torque and make driving it difficult. Also itll make finding a smooth idle very hard.

Although it sounds realtivly cheap to get all the bits, mapping it will cost a fair bit, to get it done correctly and to get the best from your engine takes a long time on the rollers.

 

[BenR]

you wont really be able to use any base clio tbs as theya re awful in their own right....but if persistent, you could use twin 1.4 items.....as they have the injector and TB all as one with potentiometer and idle valve etc etc.....BUT they are crap.....constant injector running, not even group or sequential firering.

anyway, i was talking about the jenveys as a mate in HK is the distributor for them and the thin 30mm TBs with 40mm chokes are ony 400 quid or so.....but fitting, manifolds, mapping etc etc will cost a small fortune.

BUT, running on 40s will be too small for a high revving 2ltr, 45s will be right, but you need to consider what you want the motor to do, which cam your gonna run, what rpm band youw ant to stay in etc etc.....you can have a smooth idle with TBs as mapping it is one of the benifits over a carb, but idle might be 1500rpm with a really silly cam.

i think the 30mm items from jenvey are perfect of the space lacking clio.......

and from memeory (if it serves me right) the clio RT TBs are 36mm......i think, its in me garage but i just cant be arsed...lol

 

[lofty]

im still convinced i know enough testers to get my car through on carbs anyway, its pre-sept 92 on the V5 (wheh i re-regidtered it!) a mate just got a 205 with an Mi16 on twin 45s through legaly, it must be easy enough, and i know a few friendly testers, but i have heard that soon there will be a live link to the DVLA or somthing, but i still reckon i could send a mates cars in a my plates (dodgey but would work)

carbs are so much more easy and cheap than TBs

after seeing a dirty great pair of twin 48s on that BDA escort im sold on them (if there is space for them)

 

[BenR]

ello mate, yes carbs are cheaper initially.....but body, do you have to twiddle with them often......they often go out of tune, then dependine on ambient temps etc you have to might have to twiddle a bit.

TBs you will spend a while getting it to run perfectly, but once it is, you wont need to touch it again, no matter what the temp is as it will all have correction tables in it which you worked out.

Btw, my twin 40s should be on in about a month of 2......so ill see you with your willy engine then!! LOL

 

[Ben P]

So what kind of performance do you reckon you could get from a standard 1.4 with throttle bodies?

And what about if you had head work/cam/matched manifolds?

It would be expensive but very interesting. Never been done to that extent before that I know of?

Definately something different?

Ben do you have any further info on those throttle bodies that you think might be suitable?

Oh yeah and dont forget to contact me when you are set for sorting me out some manifolds.

Cheers mate

 

[Nick Read]

Lofty - Ive been thinking more seriously about TBs as a project this winter. Only thing is I wanna spend a grand or less, sounds like the same kind of thing youre after!

I know you can get a Weber Alpha kit to do the job, but Ive never really learnt a lot about carbs or TBs cos Ive never used them. LMK if you find a way to do it. All this talk of different numbers doesnt mean a lot to me. The only carb I know of is the one on my wifes 66 Beetle and what I know from that is that its unreliable, blocks up and floods easily and goes out of tune every month!

Anyone got an FAQ on carbs/tbs?

 

[Pysco]

I doubt very mch you could do it for under a grand Nick, a set of TBs would be about 400 quid, then you need a manifold, injectors, feul rail, EMS, new wiring loom, plus it takes a long time on the rollers to get it running correctly.

 

[Captain Slarty]

all you need to know Nick is that a throttle body is NOT a carb or even similar.

it is simply a tube with a butterfly valve in it.

you would need programmable ecu with it too.

as Simon says, not for a grand , no way. The ecu would cost you that with sensors, harness and mapping, possibly far more.

 

[Captain Slarty]

Brun, the 400 you quote is misleading m8, sorry.. the base unit is just over 400 plus vat. Then you need a full harness, appropriate sensors, and mapping.. look for nearer 1-1.5 k.

Joe.

 

[2 live]

whereas carbs could be done for a lot less mmmmmmmmmmmmm twin 45s lol

 

[Pysco]

twin 45s will work, but you wont pass an MOT with them, and they need adjusting often and need tinkering with when the weather changes, TBs you just fit, map and away you go.

 

[Captain Slarty]

I bet I could get a pair of 45s through an MOT lol !!!.

they used to be my bread n butter !... they are seriously kewl, but cannot offer the flexibility of modern computer controlled systems... but the idle, yes, I have no probs with that aspect Simon lol !! - it CAN be done.... especially WITH vvt on the later units...

Most of the problems with dcoes are simply people using too big a choke size leading to poor venturi effect hence gas flow at low rpm in the mistaken belief that top end power is the name of the game.. it isnt...

Some of this misguided belief has passed to tbs also... if you choke them too large, you will have a peaky top end and crap mid / bottom end...

I offer a challenge...

Compared to a std or chipped ecu I will guarantee more power and flexibility from a pair of correctly jetted and choked 45s on any valver or even 172 than the std setup.. (Providing either or genuinely experienced carb bod or I set them up lol !!)

the only way this will be bettered is with an aftermarket ecu... (as far as raw power and outright flexibility is concerned) the cold start, idle and fuel economy will also suffer with DCs..

Dont write off the good ol DCOE just yet m8 lol

Joe..



"I love the smell of R40 in the morning"

 

[Captain Slarty]

and another thing LOL! !!

Sorry my m8 Ben.. but..

CARBS do NOT go out of tune often as you say.. it is simpy the lack of compensation for atmospheric and wear that is not allowed for (Some allowance for atmospheric,, but none really for wear...

Joe..

 

[Pysco]

LOL, I wasnt questioning the use of DCOEs as a performance enhancing mod. I would put huge sums of money on them beating any standard renault induction system. But like I said theyre not really practical for day to day use unless you like tinkering with them.

True what your saying about choke size, too big and you loose low end torque, also if there too big you get big changes in airflow for a small throttle change, which makes driving hard and mapping a b**ch.

 

[Captain Slarty]

I must (oooops sorry, dont want the wrath of Nick lol) disagree.. they can and are perfectly usable on the road if set up properly.. the old MG Maestro was a hoot.. it used 40 DCNF carbs (2) - a DCOE but in downdraft not sidedraft.. the Lotus Sunbeam, My hs Chevette, the RS1800 etc etc.. all perfectly drivable but maybe not up to modern standards...

Yo dont need to Tinker Simon, just be prepared for a slight variation related to prevailing conditions and its fine...

a good analogy is listening to a great track on the cd.. you might lose a wee bit of bass or mid range in the car compared to your home £5k system.. but it;s still offer the goodies and give ya a buzz lol.. and at the end of the day, the buzz is what its all about.. a sharper trebel response maybe considered naff in the hifi arena, but it gets yer attention in the car over all the added noises and ambients, and adds to the overall brain fart experience ..

Joe..

 

[Pysco]

So if I wanted to fit a pair of 45 DCOEs I need to sort out manifolds, throttle cable, feul pressure would need dropping a lot, would the ECU be able to re chipped and just leave the injector conectors hanging free?

What about the MOT how would you get through? What sorta gains are we talking about? 20bhp? What about feul economy, any estimates?

What actual benefits do TBs have over carbs except consistant performance and better feul economy?

 

[Nick Read]

Simon - you can be assured that Slarty wont provoke my wrath on this one because quite simply I dont claim to be an expert about stuff I dont know about and havent actually experimented on myself. But Id be interested to see how it works out on your 16v if you do go for it.

 

[Pysco]

Nick, I was very close to do doing the conversion before, but didnt on the grounds of MOT and realiability, but if Capt. reckons he knows these things inside out id be willing to give a try., guess iy depends on how much variation and bad feul economy youre prepaired to live iwth, Ive also been talking to BenR about doing an ultimate spec head, trying to find out what the biggest inlet valves thatll fit are, no point just going to carbs or TB really, gotta improve the flow aswel to see the best gains, but then you alreadt knew that

Im not taking sides on the ram air thing, just trying to take a balnced point of view taking into account facts avliable, theory and the laws of physics, I hear what your saying with Occums Razor and I Joe has a bit of a big ego, once you have eliminated the impossible, whatever reamins, however improbable, mst be the truth.

Ive asked by brother to speak to some of his lectures, Im sure then well have the defifniative answer, well youve already got it, I mean the definitive theory, not many people on earth no more about car design and engines than the guys at Loughborough.