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Twin 40 webers
- Thread starter p carr
- Start date
Hmm I considered it for a short time but there are a few things to consider.
Firstly you would need a custom inlet moanifold made up. Asuming you managed this you would also have to deal with the fact that carbs need a lot of attention to keep them running sweet. Also could be a problem come MOT time. Yes power gains are possible but it would be a lot of work.
Also its not jsut a case of sticking some twin 40s on. You need to get the right choke size etc. Someone on here (one of the other Bens I think) was saying they thought a Jenvey 38mm might work.
Personally gave up with the idea, but if you get further than I did let me know.
You could do it. You need a pair of carbs (weber or dellorto 40s), choked and jetted to suit (not really my area).
Inlet manifolds are available, try demon tweeks or rally web sites. You will need a low pressure fuel pump, (facet etc) and a fuel regulator (filter king etc) to get the correct pressure.
Then you disable the injection f/pumps and remove the standard filter.
Get a throttle linkage and connect the cables back to the pedal. I think the carbs hit the rad so need to tilt it forward or shorten the manifold.
Get some air filters and the whole lot set up on a rolling road.
Be prepared for large fuel bills and awesome noise!
Would be different wouldnt it? Plus carbs are a lot cheaper these days.
The main issues I see are:
- Getting rid of injection system for older technology = less efficient, less reliable etc
- Getting a custom inlet manifold made up. Anyone know of a company that would do this?
- Increase in fuel consumption. How drastic would the difference be?
I remember speaking to Nick Hill a while back and he said he used to have a van which into which he stuck a 1.4 energy and then converted it to twin carbs. Ill give him a call tomorrow and get back to you
Ben
Why do you need a specially made manifold? I should think someone made a batch of them at some point.
It drastically increases fuel consumption. Why would you want to put them on your car if you didnt already drive it flat out everywhere? Therefore you will drive your car at high revs and at full throttle and you will use a lot of fuel!
It is old(ish) technology and they will need setting up regularly depending on mileage. Cold starting in winter will be problematic and you will have to add a manual choke if you use it everyday and mornings etc
twin 40s are abundant s/h and new and are cheap, you can get a set of brand spanking new one for not much mroe than 400 quid.
Jetting and main venturi sizeing to suit would need to be sorted, but would also depend on what other types of mods you have or have planned. No point restricting it to a 32mm choke and then port the head so you have to up to a 36mm and rejet for another 150 quid on the rollers.
Keeping tehm in tune is a bit annoying, but only raelly becomes a prob in seasonal changes when temps drop or increase drasticly. But then you can keep a set of jets for winter and for summer.
Fuel consumpetion will rise, but not so much youll die for starvation, but ti will be highly noticeable.
emissions will worsen depending on jetting.
Basically, the hardest part is getting the manifold. Best idea i can think of is making a cardboard template of your existing mounting holes and port faces, then getting a plate cut to teh template, then mating an existing manifold to it. The the fuel system as cliocup says need to be tamed down to about 4-5 psi and the lines changed.
Oh, and the noise!!!! JESUS!
JESUS as in good noise or JESUS as in too much noise for a daily use car?
Heres the deal. I am keeping my clio for quite some time yet. I wont sell it until I can afford a nice new car. mmmmmmmmmm clio cup
So: Modifying is the only route I am interested in. Now Ben I think you said you would be able to sort me out port-matched manifolds and possibly head work too.
I could get a laguna throttle body fairly cheap I would have thought, biggest problem is finding somebody to reprofile the cam for a sensible price. Add a Hill power chip and 50bhp of NOS and Im in business.
So twin carbs would be a lovely addition to the afore mentioned mods but as I have no experience with them, maybe they would be trouble to maintain etc. 2 sets of jets is a good idea though.
What I want to know is this: with twin carbs, what happens to the ecu? Obviously you nolonger have injection so does anything need to be done to this? Would a remapable system be necessary or is this just for race engines?
Sorry for the essay, I am getting excited again!
Hmmm any idea how much they would charge?
I think the only way of doing it would be to give them an inlet manifold gasket from our car (or a second hand inlet manifold from a scrappy)
They would also need a twin carb manifold to see how to mate them together.
The first problem though is finding out what size carb to use.
I spoke to Nick at Hill Power today and he basically said not to bother. he said he wouldnt advise scrapping injection for older technology carbs. He also said injection provided more efficient and more reliable power.
So not much good there then.
Do you know exactly what components would be necessary for a conversion? Obviously inlet manifold, 2 x carb inc linkages etc, and a low pressure fuel pump.
What else? - I am still interested in this idea
well, a new ignition system as you would be scrapping the ECU.
basically, yes, swapping injection for carbs on modern cars is crazy, but on the SPi we have....anything is better!!!!!
but if you cant afford TBs then DCOEs are teh way.....or DCNFs if you have little space.
Twon 40s and depending on the cam profile you decide on, the rpm range your expecting to run will affect teh choke sizing, but i would go with 32-34mm and if you running high rpm abouve 6800rpm with a lumpy cam and low end smooth runign aint a prob about 36mm.......but it does all depend.
The you have to get the thing jetted, rolling road setups cost about 150 quid to get sweet running. Which aint to bad considering the fiddling.
Thanks Ben R. what about the ingition system from a old 19 or do they run injection too ???
And Ben P yeah im still interested too im going to have a chat with Mc donald racing up here there my local rolling road and they do alot of work with carb cars and they set my brothers up for him ill see what they have to say about it.
If you are looking at puting on an aftermarket ignition system and having the advance curve mapped to run with a twin carb set up , you will still have to buy or have made the inlet manifold. SO WHY NOT spend only a little bit more on the engine management system and put throttle bodies on to the engine in reality it will only cost slightly more than the route you are looking at with the carbs.
eheh.. this post is becoming really nice!
Throw away your ecu. Get a new engine management. No doubts.
change std SPI for the laguna 1.8lts one? No more SPI and do the work to fit the megane 1.6lts MPI? 4 TBs with 4 new inj making a new MPI?
hum... is this the thing to surprise the VTS owners? just got a bunch of them on the local cafe... if only I had a 9mm...
Hmm interesting point about the multi-point conversion. I wonder if there is a way of putting the 1.6 megane engines inlet manifold onto the clio? Its an energy engine afterall so maybe there are some similarities?
If the manifold fitted then the fuel rail should go in okay but I dont know how you would go about getting your ECU to cooperate.
On a side issue Ive seen a couple of ads for second hand carbs. A couple of pairs of mint twin 40s for around £150-£170 - Now you can see why its tempting.
Yeah there are a set of 40s in the back of max power for £120. with a manifold ( off a different car that is ) but thats the 40s side of the manifold need to think about getting the other side made.
The 1600 energy engine is the same as the 1400 i hade a look at one before as i was thinking about a transplant the differance in the two is the top of the engine the top mount is different and the coil and thats on the rocker cover as its a muilty point but other than that the engines look just the same
its like this ...
.. and I have a VAST amount of experience with weber carbs (especially the DCOE and DCNF variety).Carb can be EXTREMELY economical AND deliver great power, and indeed, low emissions.. they are great on the right application and setup correctly.
the thing is, the right application is critical.
A PROPERLY designed and flowed head, inlet, and exhaust are critical along with the cam profile. (as gas speed is the key to carb usage - you need the speed - at all points in the rev/load range - to atomise fuel as it HAS to be drawn from the jet by a pressure differential - as opposed to FI)
If you get it right.. the carb will be pretty efficient, get it wrong.. and it will cause fuel atomisation problems, richness at unpredictable times, idling problems, emission problems etc.
On a 1.4 clio without good quality head work and exhaust, accurately timed - ans suitable - cam etc, they will probably be a nightmare.. especially in the winter months as the temeprature compensation is minimal.
So, I dont consider it a good route to go down.
get the head work done, a mild cam and free flow exhaust manifold and system, kewl.
as for carbs needing constant retuning as some have said in previous threads, completely disagree, I have never found this a problem is the units are balanced and set correctly with locking compound on the balance bars.
Captn S.
I aint read all the replies as i cant be bothered, but i had 40s on my last car and i loved the noise, they sound MINT! Did use a lot of petrol though but i had a very wuick car wiv em on. I had them set up about 2 times a year and never really had any problems with them.
If you want a set i am selling some. 120 and there yours, with a set of K&N filters, but you will need to get the base plates for em as i let em go with another set by mistake. lol
I used to run twin 40s on a nova 1.3, just had to get them re jetted and set up to run. Also ran twin 45s on my rally car was a ford xflow that was making around 160-170 bhp from a 1.7L engine. Setting up is the most important thing, you need to get the corect size. Acording to my chart for a 1.4 you wiould need a choke dia between 31 and 37 mm if it were fitting twin 40 setup and your reving to around 6 - 8000 rpm. But you would need to take it to a RR that deals with setting up carbs and has the spare parts to enable them to set it up for optimum performance. As for instalation they are realy simple you only have to decid on a single or duel cable setup and remember to get the linkage that joins the 2 carbs together. As for the sealing plates between the carb and the manifold i used to find the ones that looked like a metle plate with one big o ring (misab i think) worked the best. If you carnt find a manifold form any place you should be able to get one made up at a local engineering firm from some alloy pipe and some plates matched to the carbs and the head. As said above use a facid fuel pump and an ajustable fuel regulator. You will need the trumpets for the tops of the carbs aswell along with air filters.KN do good filters for them.
Go buy a copy of motering news as this has loads of parts for sale at the back and may have some ppl you can ring about a manifold.
They will make some loud induction noise aswell.
just a point guys..
a 36mm choke - even a 34 in a 40 carb is TOO BIG !!!.
you will have problems.. on a 1.4, 32 will be fine.
if you need bigger than 34.. go to a 45 dcoe body.
ben m8.. get them ol thackery washers out !.
Joe..
