View Full Version : lookin for Twin 40's info
Twin 40's on a 1600 8v GSi engine.
1) Which is better, Dellorto or weber (have been told each are better
on a vaux engine by different people!!)
2) Any other engine mods that should/need to be done to run them to
their full advantage?
3) What power should i be able to receive from using them.
Anything else that i need to know?. and its for competion use so i dont want to hear about fuel consumption!!! :D
If your going to run twin 40's you might aswell have a modded head (ported and flowed) a longer duration camshaft a good exhaust.
If you try to put twin 40's on the standard lump is will just over fuel as you wont be getting any extra air in.
The above mods all together and set up correctly should net you about 15 bhp or there abouts, maybe more depending on spec of mods.
mikeoxford
15-08-03, 10:20 PM
If your going to run twin 40's you might aswell have a modded head (ported and flowed) a longer duration camshaft a good exhaust.
If you try to put twin 40's on the standard lump is will just over fuel as you wont be getting any extra air in.
The above mods all together and set up correctly should net you about 15 bhp or there abouts, maybe more depending on spec of mods.
as techie says RE modded head. i tried running on standard 1.4 with 1.2 head - and for dear love of god know matter what jetting i used it always overfuelled at one stage of the progression circuits (theres three circuits in webers.
as for my dealings with 40s. people i have always come across have SOLD there dellortos to by webers? dont know why? webers have parts more readily available from my exprerience, and also more places tune them easier (local to me anyhow) wont go near dellortos.
ideally get yourself a high modded head. if not go for a 1.2 or 1.3 head. and you need either a 1.4SR cam shaft, OR a sporty one. ast2 always seems to go well with 40s.
mikeoxford
15-08-03, 10:21 PM
on nova-land.com under engine in the how to section, i have compiled all of the research i found regarding weber 40s. although not all the infromation you are asking for above, u may find it an intresting read? let me know anyway
As soon as Ive got my new exhaust on im going to be rolling roading my car to see what sort of increase my modded head has made. (D.I.Y job)
At the moment in my garage i've got a 1.2 head, a 1.3 head, and my old 1.6 head. Interesting to see the difference in ports etc. The 1.6 valves are a fair bit larger so its worth I think modding the 1.6 head to similar flow as the 1.2 which has excellent ports, just tiny valves..lol.
so is it just the flow of the 1.2 or 1.3 head thats better?
Ill have a look at that Mike. I remember now seeing it before thinking it would be handy some day but never thought of it today!
When my rally car started it's competition life, it was decided to mod suspension and brakes first and engine later, so as things went the car competed in 6 events as a COMPLETLY standard 1200 nova merit with a pair of twin 40 webers, they were set up by Spamspeed in Bristol and worked a treat, no overfueling or anything, so from that point of view, if set correctly It does not make a blind bit of difference in my experience what size or stage of modification the engine is. HOWEVER, if you intend to seriously compete in a 1600 class with an 8v engine then my advice is to spend whatever you can afford on modification, eg. road/rally cam, sorted head, lightening and balance, proper clutch, proper free flowing exhaust etc.
When my rally car started it's competition life, it was decided to mod suspension and brakes first and engine later
thats exactly the way i plan to do it. except with a 1600.
Dont plan to try be competative in 1600 class till i see how i get on. plus a 1600 8v nova will need a lot of money spent to be competative in the 1600 class especially on tarmac in Ireland.
Forgot to mention earlier ill be getting a new competition exhaust system including 4 branch.
Mike, there is a hell of a lot of info there!! very good.
Techie, i had presumed more than 15bhp could be achieved. maybe ill just run the mpi injection for a while.
When the T40's were put on our 1300 there was a 28 horsepower gain.
8)thats what i like to hear!
is it all in the setting up?
It's got to be, I did try a cuple of places to get the carbs worked but until Spamspeed had ago it felt like half power, the difference was astounding just to say it was a different bloke.
I had 115 BHP from my old 1.6 Nova on Weber 40's, standard (rebuilt) head, Janspeed 4 branch, Mongoose stainless system, big Pipercross 'surround' filter on alu baseplate.
Went sweet, sounded sweeter - The 40's sucking it in and the Mongoose chucking it out - How I miss those days..........!!!
:twisted:
think i might just go for 40's so along with the competition exhaust system and 4 branch. a guy i know at home who builds mini rally cars is top notch with setting up carbs etc.
Going from whats in Mike's "bundle of knowledge" on www.nova-land.com im thinking i need a 36mm choke for rallying??? am i right in saying that?
Also will be in the U.K for Trax and if anyone has what im looking for for sale pm me thanks
im thinking i need a 36mm choke for rallying??? am i right in saying that?
ermm no lol. On a standard engine depending on what jets you run chances are you will use 30mm chokes. 32mm are used more commonly with head work and higher lift cams like 270's/285's. Then you get to the next level where everything is done and go higher again with the cam size and you are looking at 34mm chokes dependant on how you want your power delivered.
lol. ok i didn't read it properly so.
i don't know whether to run webers with the standard engine including the exhaust or maybe get a cam . i dont want to go too cracked to start with but would like a little more poke!
Twin 40's on a 1600 8v GSi engine.
1) Which is better, Dellorto or weber (have been told each are better
on a vaux engine by different people!!)
I've heard dellorto are smoother but TBH I dont think there isnt much in it - they are both very similar and good enough to get you good power.
2) Any other engine mods that should/need to be done to run them to
their full advantage?
Flowed big valve head is a must. Stick with 1.6 head and get it modded at somewhere like Bill Blydenststein. The profiling of the inlet valves and valv e throats by a professional is critical.
Match the manifold to the carbs and the head by careful porting work
A suitable cam would be 285 duration or longer - the Kent AST 2 cam gives a good even torque curve but 300 plus maybe better for competition. There is only so far you can go with increases in lift. Enem have a good name with competition cams. Piper are also in the running
If you expect to rev over 7 - 7500 rpm consider getting your conrods shot peened and ARP big end bolts
Raising the CR will be a big boost to power but the valve-piston clearances need to be carefully calculated. Needs to go to a specialist auto engineering machine shop to work out what to take off where.
You will need to pay attention to avoiding oil surge and expellation of oil out of the breather as this will cause you major problems as soon as you hit the track
3) What power should i be able to receive from using them.
140 - 150 hp is pretty easy to get
Anything else that i need to know?. and its for competion use so i dont want to hear about fuel consumption!!! :D
Make sure the bottom end is in good order ( bores not worn etc) else all that will happen is you will start to burn oil big time in a few thousand miles which will knock your power down dramatically.
thanks cp. very helpfull.
mikeoxford
19-08-03, 10:49 AM
Make sure the bottom end is in good order ( bores not worn etc) else all that will happen is you will start to burn oil big time in a few thousand miles which will knock your power down dramatically.
as i have found out the hardway TWICE :lol:
rebuild the bottom end - its the only way to get maximum results for a longer time.
isnt much work involved TBH
after reading everything here i think ill stick in a standard GSi engine to get going and plod away with work on another engine. when its ready (with no presure on me or my wallet) then ill stick it in.
Thanks for all the help :wink:
Ben (lurk75)
20-08-03, 03:08 PM
Brian,
From what i have read and heard from people you are better off going full out and doing the whole lot rather than just doing 2-3 of the aspets of it.
We have got a dead bottom end you can take back with you if you want to rebuild one, probably got a few other bits and bobs that might come in adny if your going to rebuild an 8v.
Thanks Ben. I'd say thats what i will do. thats why im not going to put any time scale on it. ill work away at it in my own time.
Ben (lurk75)
20-08-03, 05:37 PM
Ah forgot it was you, no you cant have the bits! oh yeah i smashed your clear clusters as well.
you won't believe the amount of wires that ill cut in that 16v!
Ben (lurk75)
20-08-03, 05:43 PM
there aint no wiores in my 16v and the red one you can do what you like to.
there are two 16v engines in question here!! :wink:
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