A few points on the above... You cant use an inlet manifold from an engine used in an inline/upright application in a Golf as (obviously) the engine tilts backwards, so the carbs would face downwards and would never run. If a long manifold is shortened then the port runners wont line up due to the difference in the spacing of Webers and the standard inlet ports. I doubt a manifold designed to fit a single DCOE/DHLA onto an 8v head would ever flow correctly, let alone enable an 8v to produce anything near 200hp (no disrespects meant at all), more like 130/140hp tops. A crossover style manifold was available years ago to fit a single side draught carb to Ford Pinto engines (made by Lynx manifolds), they were total ****e. For those wanting to run twin carbs on a MK2 (or a MK1 for that matter) the servo is easy to sort.. take it off (you girls! ) and push harder ! I think the clearance is tighter against the bulkhead on a MK2, so that is obviously an issue.. for competition use just cut a hole in the bulkhead and build a nice big airbox (i.e like on a Mini), but check any regulations first. No Chris, in standard form the 8v Mangoletsi's are total cack. They can however be internally modified (i.e ported) to work very well, even for 200hp engines. Even when fitting twin side draughts to a standard engine, both with the standard small ports of the manifold & head, the angle of turn as the manifold joins the head is very poor. it can be straightened up a fair bit by opening out the ports (as you would/should be doing on a decent engine anyway) and blending in the roof of the manifold & port. You end up with an egg shape to the top of the port but that's fine.. I have some pics of this if anyone wants to see it. When opening up the ports to the correct size to suit a big valve head you break into the bolt holes. This is'nt a problem as long as the head of the fixing bolts are sealed off with sealer and the shoulder of the bolt holes in the manifold are squared off so the bolt head/washer sits square... never had a problem yet using this method. On Mk1, 40mm trumpets fit fine, as do 60mm (which work better on competition spec engines). The main clearance issue is the clutch cable touching the trumpets on a Mk1, tho this is easy to fix. Not sure what trumpets will clear on a Mk2, I "think" 20-25mm will be ok, 40mm will be fine on 3 cylinders but will touch the servo on the end, I've seen this on carbs that came off a MK2. A custom manifold that tilts towards/into the raintray cant be used with carbs for the same reason as a manifold designed for an upright mounted engine wont work.. carbs will flood at such a steep angle... throttle bodies are obviously fine at that angle. I started looking at a custom manifold with longer runners to be used with carbs (metal in my fabricators eye put that on the back burner!), but to be honest, as good an induction length as most engines will need (even high power ones) can be achieved with (modified) mangolcrapsi's and 60mm trumpets. And breathe...
......oh poo....you mean I needn't of got my money back on that VWM I got hold of [:^(] that was exactly the problem with that, but hadn't even thought of doing that to be honest Wonder if he still has it......
top info there cheers what about running the manifold runners over the top of the engine a-la-16V and putting carbs at the front ? I saw one of those lynx manifolds last night - still available is Aus - useful that you say its crap as I was about to buy one for a single 45 So for 180-200hp, do you need carb area of 2x40, 2x45, 1x50, 1x55 or what ? whilst having in mind tractability Cheers Rob
When I was talking to a mate of my dads who is a mechanic and has built rallied various cars, he said if I were to take my engine any further (1.8 gu with ported and polished head with standard size valves which are smaller than GTI ones) then it would need a pair twin 45s. So I would have said if you were going for a 2.0 bottom end and are aiming for 180 -200 bhp then a pair of twin 45s would be the minimum. It was only a pipe dream at the time so I didn't go into any more detail regarding choke sizes, etc.
crossflow manifold looks canny for a downdraft lash up [mg montego carbs?] some good pics here or may run over the top in a backwards valver type arrangement. is this for carbs or t-bodies as i have some gixxer ones cluttering up my desk at the mo
Yep... You also cant use a gasket as it would be so thin around the top it would squeeze out when tightened up. I just use a thin bead of sealer (Vauxhall stuff in a blue & white tube) and wipe off the excess in the port runner with a long thin screwdriver with a small piece of rag wrapped around it (and stuck to the screwdriver so it doesnt dissapear down into the head !).
I have thought of that before, but I'd imagine the weight of the carbs is likely to cause the joints around the head flange to crack quite regularly. I know it could be braced between the flange and the pipe as it starts to bend up around, and the carbs could be supported with little legs up off the cam cover flange, but it seams like a lot of work when good power can be had with a more conventional set up. There are other options if yr looking for a lot more over 200hp... like more valves. The other thing is, bends in tubes dont flow as well as straight(er) runs, so what you may gain with the induction away from the heat of the exhaust you may loose with the air having to turn a fairly long corner. A 2ltr Pinto can produce more power on the standard manifold & DGAV than it can on a 45 with all the twists and turns of a Lynx type manifold. They were mainly used by the rally boys when restricted to use only 2 chokes, the thinking is 2 big chokes in a sidedraught has to be better than 2 small chokes in a downdraught, but then strangle it with a crap manifold! That sort of power is achievable with 38mm chokes, so 45's will be needed. Mine is on 39mm chokes but in 48's (they were cheap and available) and produces 190+hp, though will pull from 1,800rpm on a light throttle. My customer hillclimb engine is on 38mm chokes in 45's and that is touching 180hp with more to come (camshafts are the key but not the topic here), that will accept a little more throttle but has a much tammer cam, tho does'nt pull anything like as strong, and both are 1800's. Horses for courses.
this is a toy but I want to keep it simple as can be, I have a complicated animal race car already - hence avoiding a crossflow head. 2L bottom end, ace BV head, rally cams, looking like twin 45's (although I would like to be more original on the inateke front.....like the idea of trying to make a 4 barrel downdraft work actually), about 10.5:1, 180hp hopefully. Still to be decided is exhaust manifold as these seem in short supply for aba-tyle tall blocks and rigth hand drive....
yes like a holley.......could be cool and a big ass chrome air cleaner out the bonnet - 4 pipes brought together into a bunch, (wont be equal length runners without too much work but so what....), holley on top......no bulkhead clearance issues
Ah, I didn't realise it was for this. Suprised on engine choice tbh Don't hold back from a Member's motors thread, however brief...
wonder if you could get one of the guys who makes exhaust manifolds to do it. something like toyotecs wolfR exhaust manifold, with a plenam above the collector transitioning to the 4 barrel. there would be some nasty wetting on the way to the valves tho. Any reason it cant be EFI? as the bottom half of a crossflow manifold, gixxer bodies [easy to space] on top and injectors in the stock location would be pretty effective. and 4 ram pipes poking 6" out of the bonnet would be tough
I believe Lynx do manifolds to run single 40's/45's on a mk2 8v, I've definitely seen one used on a driver lump
