Hybrid_From_Hell Posted September 7, 2010 Share Posted September 7, 2010 Right those who know I have a small issue with whats left of the original air box - 1 - Its beaten to death 2 - It was a replacement for the one Eales built, and isn't big enough 3 - I need one for the engine The Plenum is a la piccie - 3 Butterflys, these are mounted on a 10mm ali plate, which I can mount to but need to have on the engine in the normal place, with a 90mm entry hole for the V8 90 air box at the back. JE Has confirmed the V8 90 air box is fine, and no he oes make air boxes any more So, on the engine it will look like this : And no, I have cleaned the inlet and trumpet base, not the plenum yet, whated to do this before it comes apart into bits So, I have enclosed a CAD (Crayon Aided Design) of the best idea I have had yet. The 3 holes ali plate would have some means made where I can bolt on a curved plate, welded up radiator end, and the bulkhead end, except on the bulkhead end this would have a 90mm exit to the V8 90 air box. So, question are Would the curved bit be better / worse than say a square shape ? The square shape would give greater internal area for air to enter do I need to have a 3> 2> 1 type arrngement or is the 3>1 OK ? I am hoping the above would be ok, I think maybe the square rather than rounded may be better or would it ? would maybe a sqaure but just rounded off top and bottom rather than dead sqaure be better etyc - not my knowledge are here, so rather than build one wrong,asking now to get it right what do those that know think ? Ta Nige Quote Link to comment Share on other sites More sharing options...
scube Posted September 7, 2010 Share Posted September 7, 2010 Not had any experience in tuning V8’s however with that said I have had experience with tuning motorcycles.. and the bigger the air box the better for instant response, snap throttle. Really don’t know if one shape is better than the other but bigger is better.. Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted September 7, 2010 Author Share Posted September 7, 2010 Airbox is sorted and is erm "Huge" Its the connection from this to the plenum I need sorted Nige Quote Link to comment Share on other sites More sharing options...
RedLineMike Posted September 7, 2010 Share Posted September 7, 2010 Nige.... Summit like this? http://www.pipercross.net/competition/products_600_airbox.asp Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted September 7, 2010 Author Share Posted September 7, 2010 Oooo ta for that linky I'll have a god look, but sort of seems i'm on the right track Nige Quote Link to comment Share on other sites More sharing options...
LandyManLuke Posted September 7, 2010 Share Posted September 7, 2010 This thread might be worth a read Just for the welding porn if nothing else. Quote Link to comment Share on other sites More sharing options...
jonost24 Posted September 7, 2010 Share Posted September 7, 2010 Hi Nige, On a previous post, some guy's trying to use a twin plenum, but suggestions came back that this was a pig to set up and to maintain. Isn't this going to be just as tricky +1? Or different idea? Your airbox is a bit BIG. Is your house missing a Dyson now Looking good tho' Jon Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted September 7, 2010 Author Share Posted September 7, 2010 Ah The BL Twin plenums had all sorts of probs, they were made by BL quickly and on a tight budget (now theres a suprise ) IIRC they were for a race series, and built for that, they weren't expected to make it to a road motor, the splindles and shafts suffer from massive wear and the entire set up is BLs finest from the "Heath Robinson nice but Oh dear" Dept I can't remember the engines they were used on, but by todays standards althought tuned up to the eyeballs the cubic capacity was nothing special, and they had a horrendous EFI Setup even with money thrown at them Eales set up is hugely different, and the entire unit(s) are rebuildable but uses quality parts etc, and design has less forces on the units as the sizes are smaller but there are more of them. Also bear in mind mine is 2004 vintage, the twin plenums (If genuine) are equally 20+ years old Nige Quote Link to comment Share on other sites More sharing options...
Lara Posted September 8, 2010 Share Posted September 8, 2010 Hi Nige, Your air box design looks fine, although a few comments worth a thought. Looks like you have 3 x 75mm throttle bodies, and one 90mm outlet! If so then your 90mm outlet and hose are going to be your restricting feature. I know from experience that you can get well over 600bhp from just two 75mm throttle bodies. And know that a short length of 90mm dia piping will flow more than enough air for any HP your engine is likely to develop so no real worries there, just seems a lot of trouble using 3 throttle bodies and then an outlet with less than half of the flow potential of the throttle bodies! However, If you make a cover as your drawing but with an enlarging area as you go toward the inlet pipe, it will be perfect. As someone said, (within reason) bigger is better, but your scale also looks fine! And as you have done with the throttle bodies, Bell mouths with big radii work miracles!!! even in the air pipe entries! I know I am not the closest location to you but if you would like to play on a flow bench you are welcome to use mine any time you like! Lara Quote Link to comment Share on other sites More sharing options...
mad_pete Posted September 8, 2010 Share Posted September 8, 2010 not having much to go on (my fluid dynamics course was along time ago) but I would expect bigger is better and the extra size of square would be better than reducing the size for a smoother shape. Circles are better as you get maximum volume per surface area but I think the air box is slightly different deal. I'd go for big. I wondered if my snorkel/air filter was restrictive on mine so I'm going to do a test with snorkel on and one with it off at full revs and see if the MAP value is different. If the pressure is the same I'm assuming it's getting enough air. Quote Link to comment Share on other sites More sharing options...
Lara Posted September 8, 2010 Share Posted September 8, 2010 Small addition to my last post as follows. Air flow is massively important at the sides of a bell mouth / trumpet and you need to keep as far away from restricting this area as possible, (at least 1.5" on your size openings) Air flow directly above the Bell mouth / trumpet is not or hardly affected to as close as 1" from the opening on a trumpet with a well designed "bell" and a 2" throat, You can in fact have an injector right inside the trumpet opening and up to 1/2" above the bottom of the trumpet taper without affecting flow at all on a well designed trumpet with a 2" throat! Lara Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted September 8, 2010 Author Share Posted September 8, 2010 Lara Hugely useful chap Thankyou I am going to make some measurements and bung up for comment please Nige Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted September 8, 2010 Author Share Posted September 8, 2010 OkeyDokey Measurement of the throttle body unit is as follows Length 246mm X Height 65mm x 15mm thick ali with raduis ports to 3 x 50mm Throttle Bodies These are held on with 4 x resessed allen bolts 4 x to a body A La : So, Hows about I add a Ali plate behind this, so that with 3 x holes in it to line up with the plate and the 12 x screw holes this plate could be sandwiched btween the throotle bodies and the Plate but be a bigger size all around, says adding 30mm to the top and the bottom and the sides ? This plate would then be 125mm Height x 300mm Length, but then o add 90 degrees bends on all 4 corners so as to give a Lip" for a curved shaped unit to side over to bottom and sides and screwed up with sealant, the far end (engine end) would be blanked off, the Gearbox End would have a plate and a 90mm inlet tube, excuse the roughness but something like : A LA : Would the extra dims top bottom each end be enough ? Reading you post should this have maybe more space underneath less on top or equal like my scrawly sketch ? Thoughts please Nige Quote Link to comment Share on other sites More sharing options...
Aragorn Posted September 8, 2010 Share Posted September 8, 2010 One thing to consider, is in effect you're going to end up with two plenum chambers? The main one sat ontop of the inlet manifold as usual, then the second one bolted to the throttle bodies? Not sure how this is going to effect the pulse tuning effects that you get when using any plenum... Personally, if i was going to start fabricating anything, i'd fabricate a new plenum box with a single large throttle body on it. Quote Link to comment Share on other sites More sharing options...
Daan Posted September 8, 2010 Share Posted September 8, 2010 I would taper it down, as you go further away from the 90 dia entry. The pipercross one is a pretty bad design in this respect. The fact that the intake length will be different for the 3 throttle bodies doesnt really matter I dont think, since the intake air comes back together in the plenum. Daan Quote Link to comment Share on other sites More sharing options...
steve b Posted September 8, 2010 Share Posted September 8, 2010 That was my thought on it , a truncated cone 50mm dia at narrow end 90mm at other , it 'feels' like it would balance the volume per butterfly cheers Steveb Quote Link to comment Share on other sites More sharing options...
Henry Webster Posted September 8, 2010 Share Posted September 8, 2010 Don't worry about the design too much, you're not going to be short of power which ever way! ;-) Just jealous btw! Although at least with only 220BHP I am hoping to hold the transmission together for longer! Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted September 8, 2010 Author Share Posted September 8, 2010 That was my thought on it , a truncated cone 50mm dia at narrow end 90mm at other , it 'feels' like it would balance the volume per butterfly cheers Steveb Would you maybe draw me a idea or 3 so I can be sure what T F I am making Pretty please (with trumpets ) ? Nige Quote Link to comment Share on other sites More sharing options...
steve b Posted September 9, 2010 Share Posted September 9, 2010 Here you go Nige does that make a bit more sense now ? You would need to think about how its fixed to the throttle bodies, bolts all the way through with tubes to stop crushing/distortion is one way, stubs and short rubber pipes - motorbike stylee could be another. cheers Steveb Quote Link to comment Share on other sites More sharing options...
Lara Posted September 9, 2010 Share Posted September 9, 2010 To be honest I think Nige's drawing is probably the best so far on an "overall" assessment! This last one looks nice but I am fairly sure that if made to the sort of scale in the drawing, there would be a disruption in flow on the end inlet (small dia end) caused by the proximity of the bell-mouth to the walls. This would need to be at least 100mm wide at it's minimum, otherwise it looks nice, but may be a problem to fix to the throttle bodies. With the box that Nige has designed, it is big enough not to be effected by flow lengths etc as Daan has stated, and it is simple to make which is always a good thing! The air will be going in to those throttle bodies straight enough not to make any difference. Tapering down is fine but try not to make it narrower on the width any more than 100mm Your attachment method sounds good, or you could make a full box and have a simple screw on (with captives etc) flat "lid" covering a simple oblong access hole on the opposite side to the throttle bodies, to get to your 12 fixing screws for the sandwich plate. a fancy converging 3 tube design would look great but would be one hell of a job to design well enough to tune the best out of it and overly complicated for what is more than likely overkill anyway! A bugger to fabricate too! But sexy Lara Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted September 9, 2010 Author Share Posted September 9, 2010 Would it be better this way : Rather than all 3 drawing air from the end ? If so how much between the end holes and the "Front edge, would it be better made sloped (as the pic) or unsloped and having an equal air gap from the holes on each ? Whilst I may be overworrying I can bild this anyway I want to best seems the right idea and preferably just the once so importnat I consider before making Nige Quote Link to comment Share on other sites More sharing options...
Turbocharger Posted September 9, 2010 Share Posted September 9, 2010 Nige - just tack something together. By the time you've finished it'll be a tow point from 12mm plate anyway, and the weight gain will absorb your 800bhp and I'll be able to chug round you in my little diesel Ninety... I expect the packaging context will dominate the argument anyway - no point having a perfect plenum and then six miles of trunking to get to the snorkel. Don't make it impossible to fabricate either... Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted September 9, 2010 Author Share Posted September 9, 2010 ^^ Twill be Ali Anyway, either is similar to make, just waiting for Lara and others views which would be best Nige Quote Link to comment Share on other sites More sharing options...
Lara Posted September 9, 2010 Share Posted September 9, 2010 Nige, If you were talking fast flowing "wet" air then yes it would be better, However the aim of your air box is to run at "Zero" under pressure and to run fairly slow air speeds, your airbox will flow only air and no atomised fuel, therefore your first design will work admirably! Extra trunking and bends in the air pipe will cause much more problems than any pitfalls in your design. Stick with your basic design, it looks fine and will work well! AND you can finish it this weekend rather than taking days of work to make a fancy box for no actual gain! Good luck, Lara Quote Link to comment Share on other sites More sharing options...
Lara Posted September 9, 2010 Share Posted September 9, 2010 More pages for inspiration. I like this one!! Seen at this link! http://www.wolfdirectracing.nl/joomla/index.php?option=com_content&view=section&layout=blog&id=6&Itemid=6 Find out the cost, then chat to me, perhaps we can knock something up! on a one off basis Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.