probably not the right area but thought id get abetter chance of a decent response in this area. does anyone have any decent info on airbox's? i have a rather large carbon airbox i plan to use on my 8v on tb's. however now i have the backing plate made up and the thing sitting on the tb's and engine i am maybe thinking it's overkill. using rough calculations the airbox is about 25 litres. i plan to feed the box with a 75mm inlet pipe. tb's are 45mm. intial engine as a fairly mild 1900 lump but im building a screamer 1800 lump with all the right bit's to hit 8k rpm. however it's going to take a bit longer than i want to get the screamer together due to a buggered rod cap. not sure whether the bulkhead surgery required to fit will be worth it...
Off the top of my head 10lts per 1000cc rings a bell. So a 25 ltr box will more than ok. When i did mine the biggest i could get in was about 15lts so i used the biggest air filter/intake pipe i could find. Didnt seem to sap any power when we ran it up on the rollers .
Good call... Bulkhead clearance IS tight !.... As yr running t/b's, how about having an inlet made thats more downdraught ? it'll largely cure yr clearance problems and the clutch & speedo cable's being in the way. Was going to do it on mine if i used t/b's, but carbs wont work at such a steep angle. If you dont want to do either, you can still get top results with an off the shelf manifold (it WILL need HEAVILY modifing internally) and long enough trumpets, though yr airbox will need to be smaller than ideal. Though as Graham proved above, it wont necessarily restrict power ! What rods you using/whats up with the cap ?
tight is an understatement. seeing that pic has given me the fear of how tight it really is. beauty is i have converted to lhd drive so i've got as much to chop out as i need. one end is in line with the cam pulley and the other end sit's about 3-4" past the end of the head. box is about 54cm wide, 23cm high and around 20cm deep. it has a flat back plate which sits against tb's and is about where carbs bolt onto the trumpets. really don't think i'll be abe to see whats what until i get the engine in the bay with the box off and backing plate on, then i can measure the clearances needed all round the box. :S i plan to heat shield the tb's and box with some high temp silver cloth stuff and i'll be heat wraping the manifold and sealing it with high temp paint. i'll try to grab a photo of it tomorrow to show the size of the thing. cheers for the info on your box GrahamV, didn't really think the size of it would be overly improtant. (no doubt mr trendy tramp would be able to prove other wise!) i reckon it should do the job pretty well. anymore thoughts?
I'll try and measure around mine in the next day or so, might give you some idea of what yr up against. I've got a stainless heat shield between the carbs & exhaust manifold which seems to work ok. I used a self adhesive cloth stuck to the manifold side of the shield which melted off after less than a hundred miles (the glue obviously not up to the job, the plate was de-greased before fitting) and i use a manifold jacket kit (which was an absolute MISSION to fit in place !) which is gradually undressing itself due to the stainless ties that keep snaping (guess they cant take the heat either). I think the only chance of any success is to wrap the manifold off the car and secure it with as much wire as possible.
Have you got the head sorted for this engine? If not, perhaps try a crossflow head. This has been my solution to the same problem, unless you are racing in series where the regs don't permit it.
yup heads are already well and truley sorted. 1900 isn't very wild other than light gasflow and bigger valves. other head on screamer is wild to say the least. had suspicions it's off one of the f3 type racers. luckily i'll be able to wrap the manifold off the car/engine. got stainless clips and also plan to use a good amount of welding wire (any other sire suggestions?) to keep the heat wrap on.
That'll prob be as good as it'll get for the manifold wrap. Do you know what valve size's are in yr f3 type head... is it based on a carb casting (i.e, no injector holes) ? What's up with yr rod cap ?
yup carb casting with no injector holes. the head has had a lot of skimming, height is well uunder recomended min in all manuals. compression ratio worked out at around 12.5:1 with the flat top pistons. :S. kent gs6 cam, lightweight buckets, schrick valve springs etc. off the top of my head the valves were literally touching, 41.5mm rings a bell. engineering guy i use said he had never seen any valve seats like the ones that were in the head. i fecked the rod cap while trying to extract the rod after an arp bolt ****ed up and rounded on me. disasterous series of events which probably got made worse by me losing the rag with it. almost put the lot up for sale after that incident. rods were very nice original ones that had been ground down then shot peened and balanced. on the look out for some scat or similar rods that can handle the rev's i want.
ok some pictures. please don't link these all over the bloody t'internet and chew my bandwidth! bandwidth well and truely chewed on the big ones editied some smaller ones. the money shots.. so how much space have i got to play with then? remember im going LHD so the only issue i have is the brake pedal box which mounts onto the bulkhead.
Stick with it.... The head sounds almost identical to mine (plugs stick out past the head face... bigger diameter steel buckets with shim adjustment between the valve and the bucket ?) though my pistons are Cosworth items with a bowl (11.6:1) and cut-out's to clear the valve's. We managed to go up a touch on valve size (41.91mm), look like a brass or bronze type material for the valve seats ? My cam's up a bit from a GS6 (couple more degree's duration and a "bit" more lift) but the difference is so small i cant imagine the performance being any different. I use Crane valve springs (the previous owner-s used to snap Iskey's with alarming regularity) and only ever had to replace one (found on the only occasion i've had to remove the head... due to a "foreign" body being consumed through the open intake). I would imagine you should have the same sort of power spread as i mine (3,600-8,000+) though with t/b's & mapped ignition yours should take full throttle below that (mine wont, but is ok at 3/4 throttle). I'm sure you'll be "happy" with the performance ! I would certainly consider steel rods, though i have heard that super-v engines use the Audi rod to 9k (not so sure i'd like to try it myself, but it maybe possible) though if you have ARP "bolts" that could be what you have. Maybe worth seeking a replacement and having it "worked" properly and fitting a new set of bolts, depends how hard/often you rev it to 8 (+?) and what its main use will be, though steel rods will obviously be better/give more peace of mind.
Thats a "BIG" air box (and VERY nice too !).... i THINK it will be a tight squeeze unless you mod the bulkhead a bit ! EXELLENT cam cover... Weber Alpha bodies by the look of em (though you no doubt know that), inlet looks a bit different to mine and an Ashely exhaust, the primarys are (in theory) too short but work well. Any idea of the quoted power ?
head sounds very similar indeed. a few more details on those cossie pistons would be nice. i can get 4/5 degrees cam swing without hitting pistons. got arp everything on the screamer. it only had normal rod bolts but i changed to the arp's for peace of mind and it went pear shaped from there. think steel rods are my best bet. however that will be next years engine. i want to get it built set up and running on the 1900 first of all. 1900 spec isn't that great but it should be solid enough for me to get used to the car and set up dialed in before i put the screamer in place. once screamer is in i'll be looking to do scottish sprint and hillclimb championship with any luck. andy at tracksport said the 1600 8v std rods can handle the 8k revs and be tickled off the limiter reguarly. what are the audi rods it could be ture they will take 9k? cash is tight on other things right now still got a lot to buy for the car(however nearly there with everything) and still got to paint it. might price up getting another couple of 144mm rods i have lying about done. i think the 500 on rods can be better spent right now and i have the 1900 to drop in as the test for a couple of 'new' things i haven't seen done before. cam cover is schroder motorsport, yup weber alpha bodies, airbox is ex-btcc item from those halfords civics of 2/3 seasons ago. exhaust is a modified ansa manifold. had to grind it back to get it to fit. inlet manifold is a bit of a **** design. had to cut off the vac connector pipe to get exhaust on! just as well i don't need a brake vac pipe! from the 1900 i think about 100bhp a flywheel. from the screamer i think about 101bhp a flywheel. said of course with tounge firmly in cheek.
cheers boys. will be down your way at somepoint(july/aug) with any luck rob. going to be at andy's for a few days to sort a couple of issues and get the thing a full bill of health before mapping. could you grab my number of andy and give me a call regarding mapping and crank trigger pickups? ta
just get Andy to give you Phil's number - he's the guy who'll hopefully be renting my RR - I don't have time to use it, only occasional weekends so it can earn me some money this way. i'll be coming down to run club days with Andy cheers, rob
http://www.autotech.com/ it appears not. the 16valve pulley is smaller but the 8v and 16v intermediate shafts have the same dia and woodruff placement. i had that pulley on a 16v shaft so it fits. assume it would just drive the oil pump at a lower speed (less revolutions than on the smaller 16v pulley)
