02-06-2010, 07:12 PM
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Darth Slacker
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Join Date: Mar 2006
Location: Northern NY, USA
Posts: 9,667
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 Quote:
Originally Posted by PSk
I also did not realise that all these injection systems took air pressure into account
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Most of the more 'automated' systems work with pressure as one of the maps to bounce this number off that number in such-n-such combination with another bunch of numbers to spew out a solution, ie: a corrected mixture.
Now that being said, there are certain systems out there that can be programmed/reprogrammed to be specifically controlled by throttle position with no regard to manifold pressure.
They are barely streetable for the most part though, but do pull like a train and work quite well for places where a lot of WFO work is done as the main goal is to squeeze the most power up at the top end and to get there in a manner that doesn't create a flat spot all the way to the sweet spot. (I've done throttle sensing on mine as part of the comparison between it and MAP sensing. Strong puller, great WFO, not a chance of driving in traffic or around the pits in any sort of civil fashion and 'neutral throttle' stuff is pretty much just a dream. T'would be good for circle track but not much else IMO)
There's also systems that can use both throttle position and MAP with each other or in certain sections of the rev range. For example, setting idle up to 2000rpm on throttle position then letting MAP take over for the upper end of things to get more finite mixture control once on the move.
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But yes they would have the cooler air available. Maybe that is the best compromise, not forcing but supplying cooler air?, thus a simple tube to around the ITB filter area?
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Cooler air in itself would be a sort of pressure advantage as the density is better. Ram air is simply an expansion of that, so yes, if a comprimise that got cooler air but not any forced air would be more adventagious vs sucking underhood air through freeflow filters alone.
Side note: you can't say you've never felt the power difference between driving during a hot day vs a cool night. The main thing that produces that power difference? Air temperature.
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Our cars have to worry about winding around existing panel work, etc. Never going to work as well
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Very true, but if one is willing to make alterations, better routing can be had.
EG: the front snorkle rig on a early SPICA car that sucks air from directly behind the right headlight (or in the case of tweaked GTV's, right through the hole where the right inner light used to be) vs the 'over the head' tubework types that have to go all over creation to get air from the box to the throttle. But again, even with all that added on stuff, the end result is air being sucked in from outside as opposed to 'in bay'. (lotta effort just to get fresh air, implying that it is indeed worth the effort and weight)
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So my view is that it takes a very long time to build and develop a club level race car, thus there are far more effective things that I'd be working on that will result in faster lap times than a cold air box
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Certainly.
And then once a bunch of other tricks have been done, including driver improvement efforts, go for that bit more power with an airbox.
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Oh and road cars have airboxes mainly for noise pollution reasons not power
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No, it's because they can't figure out a way to get easy to mass produce flat panel filters that will fit under the hood on the single TB that usually located up high on things. 
Noise pollution? With the low decible noise intakes generally make anyway, especially when compared to any sort of free flowing exhaust?
Even dual quads on a high rise manifold aren't that loud when driven in a civil fashion. And who cares if they make noise when you're up on cut anyway? LOL (they certainly aren't going to be setting off any car alarms)
Last edited by Tifosi; 02-06-2010 at 07:21 PM.
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02-07-2010, 09:29 AM
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That wasn't GTA/GTAm but Giulietta Sprint Veloce - 'Conrero window' - the reason I believe was that this was a way to get more air as the cars were required to run the original induction system.
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Originally Posted by PSk
BTW the GTA's and GTAm's used to run with a mesh area cut out of their airboxes so the carbs, etc. could suck directly air from the engine bay area as well ... and also to ensure they did not get too much pressure build up affecting the mixture. But yes they would have the cooler air available. [/i]
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02-07-2010, 12:35 PM
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Darkside Member
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Join Date: Aug 2004
Location: Nebraska
Posts: 2,539
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Quote:
Originally Posted by Tifosi
My personal thoughts on that are its a result of those air horns coming too close to the inside of the airbox lid, or, the fluid dynamics around the stacks when the box is closed are really disruptive. Drop the horns or go to way shorter ones and it might pick back up or even gain a bit. (dunno, just guessing, and wouldn't spend the extra $$ for another dyno run to find out)
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I too have wondered about the ITB's pulling equal pressure with the box on......just seems to me that the # 1 and # 2 would be robbing air from the back two throttle body's.
So you got me up off my easy chair to check clearance between the end of the air horns and the inside of the box............
What I found was the end of the air horns have a clearance of appox. 2.75" to 3.0" to the inside of the box and since the airhorns are 50 mm tall I have that much space from the end of the air horns to the backing plate.
The air horns:
Part # 2900-4550.................45 mm ID (at base), 50 mm (height) and 88 mm (horn)
http://www.twminduction.com/AirHorn/AirHorn-FR.html
Airbox:
http://www.twminduction.com/airbox.htm
What do you think.................enough space?
Here are some pictures
Last edited by msiert; 02-07-2010 at 03:04 PM.
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02-07-2010, 12:40 PM
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More pictures from the check.
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02-07-2010, 03:22 PM
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Darth Slacker
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Join Date: Mar 2006
Location: Northern NY, USA
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Hmm.
Using the pix, I'm getting around 2.75 from bell to cover. 3+ would be better, but almost 3 is better than some of the suffocation jobs some other filters/airbox/combinations do.
Front cylinders won't starve rear cylinders as the *volume of the box is greater than what any two cylinders can pull and with air constantly coming in, a shortage is very unlikely. Well, that and each cylinder is only pulling in air for 1/4 turn every 2 turns, so it's not a constant pull from each one like a shop vac produces. It just seems that way due to idle speed.
(*another case of 'bigger would be better' with 2L+ volume inside the airbox proper being the tits, which would be relatively huge compared to that box, but if one wanted to be absolutely sure....)
Still, the stacks do create a change in the airflow inside the box, so 'lack of proper room to move and flow' would still be on the list of why-fors, especially with the bell to cover clearance being what it is.
Mabe once the snow clears you can pull them off just for giggles to see if anything radical happens.
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02-07-2010, 07:21 PM
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Darkside Member
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Join Date: Aug 2004
Location: Nebraska
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Quote:
Originally Posted by Tifosi
Still, the stacks do create a change in the airflow inside the box, so 'lack of proper room to move and flow' would still be on the list of why-fors, especially with the bell to cover clearance being what it is.
Mabe once the snow clears you can pull them off just for giggles to see if anything radical happens.
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Would be easy test "how it feels with them on amd off".
I did emailed TWM to what their recommendation would be (using the 50 mm air horns in their 4 cylinder airboxes). It does say 50 mm is the max to use on their 6 cylinder airbox's
I looked for shorter horns on their site but it looks like 50 mm is the shortest one they carry in my size.
Thanks for the help,
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02-08-2010, 04:34 PM
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TWIN Induction got back to me on using 50 mm horns or no horns at all in their airbox and they said:
It is essential to run horns. It is possible to use 50mm horns but the preferred length is 35mm.
Through they didn't say that the 50 mm horns wouldn't work, saying the 35 mm were preferred says to me they would be better. Too bad I don't see any 35 mm horns in a 45 mm ID on their web site.
I take it that going to a shorter horn will reduce my torque somewhat but were talking less then an inch difference?
Last edited by msiert; 02-08-2010 at 04:44 PM.
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02-08-2010, 04:58 PM
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Don't forget that you're only chasing 5 hp, so loosing torque for this 5 hp is probably not a good thing.
But saying that if you want to shorten your "trumpets" stick them in a lathe like I did with mine. I machined a groove around the trumpet near the base and machined the flange so that it (now 2 pieces) fitted into this groove ... fiddly but worked perfectly.
Ah the quest to make an airbox work ...  ...  ...
Pete
ps: A common modification to Ducati's is to remove the airbox or open them up ...
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ps: Remember it's all just opinions 
'71 1750 Series 2 GTV: http://www.alfabb.com/bb/forums/showthread.php?p=208078
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02-08-2010, 05:44 PM
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Darth Slacker
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Desmo drive valves are not the wave of the future
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02-08-2010, 10:58 PM
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Quote:
Originally Posted by Tifosi
Desmo drive valves are not the wave of the future |
Interestingly though their MotoGP engine is one of the better ones, if not the best engine on the grid and uses desmo valve control ...
Pete
__________________
ps: Remember it's all just opinions
'71 1750 Series 2 GTV: http://www.alfabb.com/bb/forums/showthread.php?p=208078
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02-08-2010, 11:12 PM
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I was daily driving TPS only on my 20V toyota engine with ITB's for months...it's not as bad as you think!
I only switched to speed density in a quest to get better fuel economy around town, but my lack of economy might just be the lack of deceleration enleanment on my stand alone.
How do you suppose Spics works??
anyways, what size throttles are you using on your car msiert?
__________________
1987 Milano Platinum - check for many new items. [B][COLOR="Red"][URL="http://alfabb.com/bb/forums/showthread.php?t=42980"]PARTING OUT[/URL][/COLOR][/B]
1989 Verde - Harsh shocks and SS rears, 27mm torsion bars, stainless lines, pads, 16X7.5 rims, 4.10 rebuilt platinum tranny, poly bushes, and RSR 28mm front and 25.4mm adjustable sways!
1984 GTV-6 - 80K miles
Last edited by Grant; 02-08-2010 at 11:19 PM.
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02-09-2010, 02:19 AM
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Darth Slacker
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Join Date: Mar 2006
Location: Northern NY, USA
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Quote:
Originally Posted by Grant
How do you suppose Spics works??
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By taking initiative and showing a willingness to work undesirable jobs at a lower rate of pay? *badump~tish!*
SPICA: wind up clock that has a second hand and perhaps 1/4s of the moon.
Programmable EFI: digital clock w/daily wireless remote calibration via sattelite to an atomic clock in Greenwich, with inside and outside temperatures, all phases of the moon including eclipses, day, date, humidity, alarm feature and light sensitive activation of a backlight all in one component run off a single AA battery.
It's just not an apples to apples comparison. (or mac to mac if you're one of those anal types who sniff thier own farts. You know, a Prius owner)
TPS only on my system is a nightmare to get any sort of cruising fuel values for. This gives great power but won't cruise, that gives cruise but about as much power as a moped.
After a few tries over a couple seasons I deemed it no longer worth any effort on my part forever more. Unless I was building a circle track or drag car. (as in I gave it more than a fair enough shake and ain't gonna go though changing many, many map values to ever bother trying again only to have to change them all back again)
Last edited by Tifosi; 02-09-2010 at 03:09 AM.
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02-09-2010, 02:41 AM
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Darth Slacker
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Join Date: Mar 2006
Location: Northern NY, USA
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Quote:
Originally Posted by PSk
Interestingly though their MotoGP engine is one of the better ones, if not the best engine on the grid and uses desmo valve control ...
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And here all these years I thought the advantage was from the extra few 100 cc's given because they were a 4 stroke racing against feilds of 2 strokes. ('Say Mick, that 900cc bike is really showing the 500cc boys the way around the track today isn't it')
'Course that has changed a bit in the last couple three seasons or so hasn't it? (I stopped following a long while back due to spotty airing times)
I know the dirtbike guys, at least in arena and that whatever-cross where they use asphalt and dirt are seeing more and more 4 strokes all the time with 2 stroke now being the little guy on the grid. But that change was brought about by Yamaha whupping off on everyone with their 500cc 4 stroke ridden by Doug Henry (competing in the 250 2 stroke class IIRC) then that was followed by Honda and since the rules made allowances for bigger displacement for 4 strokes, and they finally were at least on par and mabe even beginning to excell in the torque wars, lotta folks have made the jump over.
And why not?
More everything AND almost double the displacement of whatever 2 stroke class, and very little weight gain in the process.
2 stroke F'd up when they went liquid cooled IMO. Yes you can build them tighter, but you're adding up to 30 or more pounds onto a bike gettign the system on. Goofy. (I remember when you could carry a 2 stroke 750 with gearbox around the shop cradled in your arms like it was a sack of groceries. Now you need a pallet jack)
Wow, tangents.....
Um, Murray?
Yeah, you can have your thread back now. I'll stop letting my mind wander so aimlessly on your time now.
Last edited by Tifosi; 02-09-2010 at 03:10 AM.
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02-09-2010, 07:50 AM
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Senior Member
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Tifosi:
1. The master atomic clock is at the National Bureau of Standards Lab in Denver CO. The second US slave is at the US Naval Observatory in Bethesda MD (the same place the VP residence is). Both broadcast digital, analog, and voice time sync signals on several frequencies. The Brits actually slave of the Denver clock.
2. Four cycle is fading away because the EPA has effectively banned all two cycle engines because of emissions. They can get really high rpms, but have no chance at the carbon emissions due to residual unburned fuel. Manufacturers don't invest R & D in a non-commercial product. Even lawn mowers with valves......
Robert
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02-09-2010, 07:59 AM
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Darth Slacker
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Join Date: Mar 2006
Location: Northern NY, USA
Posts: 9,667
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That's OK, I and some freinds have been R&D'ing 4 stroke lawnmower engines for many, many years now.
Some finer examples are the Briggs 5hp engines massaged, tinkered, then wound to get closer to 25hp at around 7000 rpm within the confines of stock parts, and the 3hp jobs, which only need to be 'stock appearing', pushing more than that when spooled up into the 16,000 rpm range
Makes yardwork a breeze LOL
Ah, dammit, there's another hijack.
Penalty bong!
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