Hi guys,
I'm doing some more work on fine tuning my webers and have just changed my auxiliary ventruis, but before fitting them I cleaned up the casting marks from the inside of the ventruis to avoid any disruption to the air flow. The result from doing this seems worthwhile as it now feels like the air is flowing smoother, similar to running the ram tubes with no filters.
If you look at a set of stock ventruis you'll see where the 2 halves of the moulds to cast them join there may be a rough area or ridges etc, these can't be good for air flow.
So this has got me thinking about my ram tubes again and how the mesh filters that clip onto the mouth of the tubes and reduce the effect of the tubes intended design. To stop this you'd need to either not use filters or possibly make an air box with a filter at the end and houses the ram tubes unobstructed.
There's a place in Melbourne that is making dcoe air boxes (boi performance). Has anyone out there used an air box for their webers and how'd it go for you.
It would be possible to make your own with a bit of time.
Any pics would be good.
Things to consider could be, leaving enough room around the ram tubes for proper air flow, clearance for heater hoses, clearance of inner guard and firewall at rear carb and a cold air intake is probably not possible without bodymmods.
I'd be interested in anyone's thoughts on this idea.
Cheers James
56 replies to this topic
#1
jd lj
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Posted 09 February 2015 - 03:41 PM
#2
_duggan208_
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Posted 10 February 2015 - 12:50 AM
Making an air box for a LC,J is a frOcking nightmare. if you enjoy a challenge, than an air box is right up there with the best of them. I don't have Webers but I use Weber style throttle bodies. I'm on my 3rd attempt and this one is working out OK so far. Unfortunatly, I've had to pull out the engine. The worst issue is cutting up the inner guard for clearence for the rear throttle body. I use a Duggan Head so my throttle bodies (TBs) are a little higher. The next issue is that if the air box is attached to the Webers it will hit the inner guard when the engine torques over on acceleration. So, I have a sort of 2 peice set up where a thin metal plate is attached to the TBs and the plate can move around inside an air box fixed to the inner guard, sealed by rubber seals. I've had to lower my inner guard to fit the air box, its a butchered bloody mess, now I'll tidy it all up due to the engine being removed and I can get to everything. The air box and plate is several folded and rivited metal sheets rather than trying to make up a one piece design. Getting 6 holes all perfectly lined up for 6 ram tubes is above my abilities. The sides of the air box and the plate extend up to and seal against the bonnet. So when I open the bonnet I can show of those lovely ram tubes. I have a large paper pod filter at the front of the airbox, which is fed cool air through a hole in the radiator support panel. I don't know if it gets enough air yet. I'm getting small ammounts of fine dust inside so the seals are not quiet up to scratch yet. If you can sort an air box out your engine will reward you with more power because of all that lovely cool dense air instead of all that shitty dirty hot crap that comes of your headers. Hope all that helps, I'll see what pics I have.
Regards
#3
jd lj
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Posted 10 February 2015 - 04:40 AM
I hadn't consider reduced clearance due to engine movement yet.
I won't be cutting any holes if the body, even though that would achieve better results I just couldn't bring myself to doing that. Which means that cold air intake isn't going to happen, I was more hoping to get better flow around the ram tubes so they can actually work how they're meant to. There's plenty of planning needed in this idea, hmm.
I won't be cutting any holes if the body, even though that would achieve better results I just couldn't bring myself to doing that. Which means that cold air intake isn't going to happen, I was more hoping to get better flow around the ram tubes so they can actually work how they're meant to. There's plenty of planning needed in this idea, hmm.
#4
_datpsi_
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Posted 10 February 2015 - 09:02 AM
Built my first attempt but yet to run on car. It's tricky getting it to fit in without modifying anything else. Is there enough area within the box to feed engine?? I'll soon find out. Plus there is a lot of science i have seen that can be used to help flow. . I just made biggest possible and start from there!!
#5
_Lazarus_
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Posted 10 February 2015 - 12:19 PM
Ram tubes curved upwards to be parallel to side of block, to plenum sealed against bonnet with XW GT style scoop (buy a spare bonnet to cut) ?
#6
_rich243_
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Posted 10 February 2015 - 04:37 PM
How about just making some nice ducting or pipework to direct some cool air from the front of the car up to the carbies?
#7
jd lj
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Posted 10 February 2015 - 05:58 PM
I spoke to BOI PERFORMANCE about them today, seems quite knowledgable and easy to talk to. He says that there are big improvements to be had by fitting a COLD air box and if done right you can actually get a pound or so of pressure into the box while driving.
I wonder if you would need divisions inside the box to direct air to each carby throat evenly. Would you get more air to the front carb than the rear without having these?
I wonder if you would need divisions inside the box to direct air to each carby throat evenly. Would you get more air to the front carb than the rear without having these?
#8
jd lj
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Posted 10 February 2015 - 06:00 PM
It could be good to have the same finish on the air box as what the heater box has to make it look like a factory part.
#9
_Bomber Watson_
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Posted 10 February 2015 - 06:24 PM
Dividers/distribution would be fairly inconsequential, there is no fuel in the mix to get dropped out, which is the biggest issue faced with wet manifolds.
Remember the air is being drawn into the cylinder, so long as your not totally choking one of the ram tubes, they should sort them selves out.
Have a look at some of the higher end plenums from plazman and the like for jap sixes, will give a few ideas of what is required.
Also, in my very limited knowlege, im pretty sure that air is drawn into an orifice under vacuume from mostly AROUND the ram tube, and if they have a chance even from behind it, not directly from the front. Hence we run ram tubes, to help maximize the airflow through the orifice.
A straight 1" hole say, under a smoke test, will only use about 60% of its diameter if it just has sharp edges.
This is why most proper plenum style manifolds have the ram tubes protruding into the manifold by an inch or so, look at F1 inlets for an example. Or even higher end late model jap sports bikes.
I think 1psi positive pressure is a bit far fetched, tmk pro stock cars are getting just over 2psi at the end of the strip, thats a giant big pro stock scoop with decades of development at around 300kph, I think you would be pushing shit up hill to get 1psi into a plenum on one of our little cars.
Cheers.
Edited by Bomber Watson, 10 February 2015 - 06:26 PM.
#10
RallyRed
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Posted 10 February 2015 - 09:53 PM
maybe something simple like a flat plate...?
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#11
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Posted 10 February 2015 - 10:29 PM
Thanks for that pic Col.
EH or EJ? They're are a prick of a thing to get cold air into either way.
EH or EJ? They're are a prick of a thing to get cold air into either way.
#12
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Posted 10 February 2015 - 11:15 PM
Another idea is to attach mandrel 45 or 90 degrees bent pipes to each weber, just like a ram tube, hose clamp a rubber hose onto that and then clamp the ram tubes into the hose. I've seen this done on V8 mechanical injection systems. That should give enough clearence for the airbox without cutting the inner guard and as suggested above by Lazarus, a bonnet scoop with a filter underneath. EFI Hardware in VIC supply air boxes for Weber style throttle bodies, might be able to adapt to your Webers, they have an air filter on the front. I've also thought about the distribution of air inside the airbox, the possibility of the first throttle body getting more air. Eventually I'm going to make a bonnet scoop and filter that attaches directly on top of the existing air box, evening out any chance of uneven air distribution.
I like that EH idea, might not be as good as an enclosed box but i bet that would still make a significant difference, don't have to cut the inner guard or a good bonnet up. I suppose they just use foam filters over the ram tubes. Also keeps the fuel cool.
There was an article in a magazine, more than a few years ago, where an FC Holden 202, Irving head dyno tested an alloy plate between the headers and the inlet manifolds (Dellortoes) and covered most of the complete section in the engine bay so the manifolds, carbies and ram tubes were seperate. it developed an extra 25 HP. So well worth doing.
Regards
#13
_Agent 34_
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Posted 11 February 2015 - 05:40 AM
One of the problems with the torana is that the engine bay, once the stone tray is on really has no where to get fresh air into the carby area, unless you start cutting out parts of the radiator ( vertically 3 inch x 8 inch ) and removing head lights.
I read steve vizards " how to build horsepower over the crissy break and there is one advantage to separating the intake from the general engine bay air. We all know affects the holden motor has as the exhaust is on the same side as the carby thus / lowering the temperature of the charge and keeping the heat out of the carbies is important.
Heat shields do two things 1)- deflect heat away from the carby thus reducing heat sink 2) separating the charge air to take the coolest air into the carby
You will see the cold air intake in the photo and at least this is " filling or diluting the engine bay air temp " and thus lowering the charge.
there is a few things about the old SU carby VS the webber and you will see what i'm talking about;
surface area - the SU has much less surface area and is not as wide
manifold - again this has much less surface area and not as wide
Now I'm no expert in heat sink or temperature of intake charge but balancing or reduction of the charge is important, I just think that the big bank of webbers needs more work to reduce heat sink and lower the charge so if you can do both then you will see an improvement
It's probably my next step is to get some heat shield and start working a template out on my car.
#14
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Posted 11 February 2015 - 08:41 AM
If worried about heat, i would wrap the extractor or ceramic coat it well before fitting a large heat shield. Has anyone got any real data on intake air temps under a bonnet at speed? In the same vein of thinking perhaps making sure the heat can flow out is more important , again would like to see/hear of pressure drop tests. On some landspeed racing cars they create super long cold air ducting to reduce the ram air type pressure. I think there are some double sock ( fit over both trumpets as one) that have a frame and you can secure them at different heights... so in theory you get filtration and still get the space to not impact on radii / air speed etc.... again whether they fit is the issue...
this is said , as someone who likes the look of the bare triples!!!!! , but also someone who likes to see the data rather than just rely on hearsay..... but having said that , if you are keen go for it... keep thinking outside the box(pun intended) Darryl
#15
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Posted 11 February 2015 - 08:43 AM
Hi Jonesy,
EH mate...it was on the web for $30k ??a few weeks back...nice looking thing.
as for the airboxes.....
I have noticed that a lot of the fast Nc racers do not have any form of heat shield / airbox ( not sure fully enclosed airboxes are legal anyway in Nc?)
but a couple of the guns do run that perforated looking sheet between the extractors and the carbs.
My understanding is that bodywork mods are not allowed...thus to get the air flow you do see some guys with custom radiators that actually have the 6" hose for the fresh / cool air passing thru the guts of the radiator.
Of course, if you are not racing in a controlled type class......do as you want I guess.
Would be good to see someone do this airbox thing with back to back dyno runs...as noted above....reckon if it showed good returns, then you'd be selling them by the dozens....just like they do with OTRs on VE Commodores etc.
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#16
Peter UC
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Posted 11 February 2015 - 06:12 PM
^ Correct, in Group Nc a airbox isn't allowed, they would definitely be running one if they could. I have read up about airboxes and you pretty much try and make it has big as you can, motorcycle engines tend to try and make theirs about 10:1 ratio of airbox volume to engine volume. Also one thing to note if you run one is to move the carb fuel bowl vent into the airbox (with a tube or similar) so the pressure in the airbox and carb is the same.
#17
_Bomber Watson_
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Posted 11 February 2015 - 07:23 PM
That last point is a really, really good tip.
#18
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Posted 11 February 2015 - 10:32 PM
Have a look on google to get ideas... E-type jags have been using em for years......
#19
jd lj
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Posted 12 February 2015 - 04:28 AM
Venting the fuel bowl into the air box is definitely necessary as the air within the carb must be of the same pressure as the air being drawn into the throat otherwise it'll bugger up the air /fuel mixture. I've even seen a small ram tube fitted to the float bowl vent once, I don't know what impact it would have on the internal air pressure but it looked cool.
There's quite a few dcoe air boxes on google images.
There's quite a few dcoe air boxes on google images.
#20
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Posted 12 February 2015 - 05:38 PM
What size ram tubes are you guys using? Mine are 100mm long which seems to be longer than what I'm told most people are using.
I've still got 140mm clearance to the inner guard, less for the rear carb due to the bonnet hinges.
I've still got 140mm clearance to the inner guard, less for the rear carb due to the bonnet hinges.
#21
_Agent 34_
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Posted 12 February 2015 - 07:48 PM
If worried about heat, i would wrap the extractor or ceramic coat it well before fitting a large heat shield. Has anyone got any real data on intake air temps under a bonnet at speed? In the same vein of thinking perhaps making sure the heat can flow out is more important , again
FNQ- i defiantly think that ceramic coating of the extractors is a must for a start.
to clear the motor area of hot air a bit better you can lift the back of the bonnet up.by fiddling with the hinges. the only guy i have seen cheat in NC ( ops did i say that ) or interpretation of the rules different was a bloke who put the a slot into the radiator as noted in my first post.
how much of a benefit it was i have no idea.
James I'll do some investigation at wakefield on the 21st and come back to you on some lengths of the ram tubes..
the problem with NC is that the rules are intended to keep the racing equal and low cost which means modifications are limited to era specs.
#22
_Bomber Watson_
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Posted 12 February 2015 - 08:29 PM
Ram tube lengh should probably be worked out with a program like pipemax, not just "this guy is running this so i will run that"
Cheers.
#23
_datpsi_
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Posted 12 February 2015 - 08:34 PM
Certainly debate the "low cost" comment... seen different motors work better with different length runners so believe it's testing the most accurate solution. .not the cheapest however but in the search for hp. Even lifting the bonnet is not allowed in nc.
#24
jd lj
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Posted 13 February 2015 - 04:07 AM
Ram tube lengh should probably be worked out with a program like pipemax, not just "this guy is running this so i will run that"
Cheers.
I'm just curious about what sizes other people are using, not suggesting that one size fits all, dyno testing is needed to find the most suitable size for a particular engine and what the car is used for (street or track) will make a difference too.
I'm not chasing maximum power here although that may be a by-product, my main aim to to make the most drivable it can be. It's already great, by the time I get to the end of my street I'm thinking wow,this things awesome, but I still believe there's room for improvement.
#25
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Posted 13 February 2015 - 04:19 AM
Some of the potential benefits of an air box, cold or not, I think could be better air flow due to letting the ram tubes work unobstructed, better filtration, reduced induction noise and containing reversion fumes whilst idling.
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