Right then....... Im a while talking about this - about 1.5 yrs in fact lol so yesterday evening I made a start on it. I will say that Ben'S excellent thread on manifolds spurred me on to make a go at this so thanks Ben + Ed - http://www.clubgti.com/showthread.php?243845-16V-ABF-Intake-Manifold-Development-(results) It possibly might not make any difference at all as intake manifolds are generally a compromise anyway but for the time Im going to put into it - its worth a shot. The main 'goal' is to get more torque at lower rpm without hurting power up top. I dont expect it to flow higher up top, but Id expect it not to be any worse. As mentioned, its for low down rpm mainly. Theres a few things you need to realize during the making of this - I dont have a mk2 to test it on, so Im going to have to hand it over to Ed to see if it makes any difference. I might fly over with it and be there with him, or just ship it over and let him see how it works. Im trying to pack everything I can in there to make it work with whatever system - that is kjet, or kr converted to efi. The Abf is out since the injector setup is pretty pigish. Im going to add the cold start fuel injector drilling, and the aux air drilling just to have them there. The main plan is to have twin runners feeding each cylinder, one runner deactivating at lower rpm. In time if it works - Ill make up an rpm triggered module to activate an arm to open or close the butterfly's on the 4 runners. For testing and to keep costs down they will be on a switch of some sort - into the cabin and switchable at say 3800-4000rpm. The construction is fairly simple and will comprise of 4 modular parts. 1, The bit bolted to head containing the 2-1 runner pairs as well as the butterflys, (cast aluminium, brass, steel) 2, The dual runners bend sections curving up - required to meet straight runners over rocker cover (cast aluminium) 3, The dual runners over the rocker cover (mainly carbonfiber + cast aluminium) 4, The Plenum, (cast aluminium) Obviously each modular part will be made of many smaller parts but you get the idea. The concept is not new and is on many cars already, the Toyotas being most like this one I guess but there are a lot of ways it can be done. It should be a pretty quick project - manifold stuff can be slow as drawing the head flange can take a while, but thankfully I have it draw from previous projects so the sizes are all 'new ground' so to speak. Will shoot up the ''so far'' photos once they have uploaded, Brian,
It might be best to fly over and I can request the guys of Garage Streamline to open on a Sunday. We can use JENVEE if I am not doing anything with it or I do not have a track day. JENVEE is already kitted out with electrical looms for plenum and ITBs so if anything is different with your component placement, then I can modify the loom to make the installation seamless.
Ed - you are a legend, this means so much as you probably know. What Im thinking of is bring the new manifold, and a 42mm manifold - run a 'standard map' for the 42mm and then try again with the new mani without changing anything software and see how it goes. Ill equip a 42mm mani with the same injectors as in the new manifold so it will all be the same from that respect. Do you think thats all ok? Thanks again, Brian,
Once it is reversible to my existing set up and does not require removal from the dyno ( to keep constancy) then yes very possible for a true back to back. That would be an interesting day
Looking fwd to it already Ed Right so gave the lower section a few hours and its nearly ready for pouring. Obviously, a pattern has to be made. To keep it simple this is a full pattern - not halves fixed to a parting plate(for speed of moulding) so Itll mean raking down to the parting line manually but thats fine for a once off. I want to have the main pattern spot on so I can take half patterns of it in time if needs be for batch moulding. Enter loads of bits of Iroko, sapele, mdf and 'pine', The main flange patterns were cut on the cnc for speed - drawn already, there is a pair - 1+2, and 3+4 The core prints added to the head side, on this pair - the other pair are assembled with the runners measuring the core diameter and wrapped with wire to make the wall thickness The white bit slides in as the others fit - this will be used to make the corebox before getting glued in too, The other gets make the very same, but the core patterns wrapped in wire to make up for the wall thickness as mentioned - its a good trick to get even wall thickness on runners, The wire gets smoothed over with filler like so, Back to the core, there is a little hump into runner @ injector so I chose to add this before making core box, I chose to make the corebox with one of the runner patterns to save time, Im 'borrowing it' to make said corebox, and when Im done it will go back into the main pattern - get wrapped in wire, and smoothed like the other pair. Its just faster this way, Corebox made half height of core pattern, Core pattern covered in parcel tape(nothing sticks to this) and the box filled with isopon and squished in, Trimmed just as pon starts to go off, Comes out real easy, The other(top) is done the very same and then we have two, to save putting the knife edge on the core pattern before the pon, I do it after in the coreboxes. This will mean the core pattern is unmolested and will fit back into the main pattern. .5mm aluminum ramps are added and filled in - its hard do a knife edge without the aluminium as you just end up sanding it all away, These get filled more when stable and blended, Top and bottom together - no dowel pins, just lined boxes on outside edges - near enough, Next, fine sand, and sodium silicate, mix... Boxes clamped in vice, pack in sand, vent holes down inside, add co2 gas to set, Open boxes, remove core, Repeat 3 more times lol The dimple - hard see on the core but its there, Tape removed off the core pattern and slid back into pattern on the right - this is glued in and wrapped with wire as one on left has been done, A quick eyeball at injector placement - I did NO drawings for any of this, just the basic measurements of stuff - not sure how Ill hold on rail yet but Ill add a pickup tab to the curved runner portion probably and bolt to that. Happy with the evenings work - the curved sections(x4) will all be the same for speed so they will be pretty fast too. Brian,
I sure will. Hopefully it will make some hp difference - on paper it does. If it doesn't, Ill hang it on the wall with a sign saying ''Heres one that didnt work at all'' so that Ill remember not to make the next one the same lol Brian,
Should be heading over to a good friend where I am to locate an ally rad fit for this and other purposes
Ya - approx 5-6 hours, So, been Googling Images of the 16v engine the last hr and its pretty tight between Oem intake and rocker cover, intake and bonnet, and intake runners between plug leads/tops but I think I should be able to squeeze it all in. For efficiency and referring to 'butterfly valve principles after a curve/bend' Im going to place the shafts upright, and not horizontal like most throttle bodies. At the minute Im thinking of turning the 4 shafts with toothed belts, and mini timing pulleys. This sounds a bit higgly piggly but it actually results in a robust, no backlash, lightweight system. Since Im not angling the butteryfly plates when closed, they pretty much have to turn 90 degrees to be full open. This is not a simple thing to do with cranks and levers as space is V.tight. I have to make a list of things later for Ed to check as regards what he has on the car - injector types, throttle body and so on so I can match to them but thats pretty minor. Thanks folks, Brian,
That means handing JENVEE over to my tame racing driver... You know I got an even better idea to evaluate this...hmm...
Fast & Speed in Holland used to have a variable length itb 16v setup. shame i cant find any pics of it.
