View Full Version : Cold Air Induction Part III
Bought some more pipe, now my car is shit hot :D
Works well once above 40mph then pulls well - close to rev limit in 5th - downside is it's liking it's fuel a lot if I drive it like that :D
http://www.seatcupra.net/~mark/coldair/1.jpg
http://www.seatcupra.net/~mark/coldair/2.jpg
http://www.seatcupra.net/~mark/coldair/3.jpg
http://www.seatcupra.net/~mark/coldair/4.jpg
max_torque
29-12-2002, 13:18
When are you getting the "Sponsored by B&Q" graphics for the side?:D
Only joking!
(you can't beat a bit of home spun DIY tuning on the bhp per £ scale)
aye - that big pipe was £13.18 from there & the right angle was £6.38
bargain & better than samco as it'll not be sucked too hard
Mark
Dormouse
29-12-2002, 17:40
as it'll not be sucked too hard
Anyone? you can't get a better invitation for an innuendo than that?
Dor.
Got a soundfile to go with those pictures? Bet it sounds fantastic :)
as long as you're not accelerating it's not even noticable, BUT
if you blip the throttle it sounds the tits, then when you put your foot down full throttle it makes people from as far as you can see turn.
muhahahah
will have to see if any of my phones output to wav's or mp3's
Mark
Dormouse
29-12-2002, 21:27
Feck we should have though of that. I had my video camera all charged as well.
DOH!
Dor.
hopkinsgm
29-12-2002, 22:21
Mark - what sort of diameter is that length of flexy pipe onto the sh1t pipe? I feel a plan coming on... If only i'd robbed that chunk of alu duct out of the skip the other week... :(
it looks like a broken leg plaster cast,but it works,my ideas do work sometimes:D
Oh dear, I am tempted to do the same thing:idea: :help: :yikes:
Was thinking of a more Proffessional approach (if thats possible:p )
using not too expensive Samco angled pipes and a Stainless induction pipe (http://www.bansheemotorsport.co.uk/Induction.html) from Banshee motorsport or som other bit of mild steel/ally tubing from the scrap bin @ work.
Now, as my airfilter neck is 50mm as apposed to 100mm on spi engines
do I :
A)Make the new induction system 50mm diameter all the way through utilising the existing cone filter
B)Increase the pipe diameter as much as possible (this would require a new Cone filter) but later reducing it to fit the AFM neck
the other thing is would this restrict the engines breathing (like sucking thru a long thin straw) at all and make it worse:confused:
it's only going to move air past as fast as the narrowest part if that makes sense.
In other words it will only have a negative effect if the pipeing is of a smaller bore than the neck of the AFM.
but will pipeing larger than 50mm up until the AFM as apposed to 50mm throughout will be better?
max_torque
04-01-2003, 22:56
A normally aspirated 2.0 litre engine at wide open throttle, and making 100% vol eff at peak power, with a plenum temp of 25 degc will be pulling 0.136 Kg/s of air.
In a 50mm pipe the dymanic component of pressure (the bit that is lost through wall friction and incomplete pressure recovery after compression) will be 1.35 kpa.
Typically when designing an intake system a good target is to aim for around 1 kpa maximum dynamic component. IN this case this will be created by a diameter of 54mm.
Ideally i would aim to have an intake pipe diameter of say 60mm, until 50mm infront of throttle body, where i would have a diameter of say 100mm, with a nice 7degree cone leading from the 60mm to the 100mm, and a nice radiused bellmouth down from the 100mm part that exactly matches up to the 50mm diameter.
This system will then have a low wall loss in the main part, then use the increased diameter of 100mm to decelerate the air, increasing it's pressure by recovering the dynamic componnent (which we know is less than 1 kpa, but worth having as it's 1% of atmospheric) in the nice 7 degree cone, then use the bellmouth to smoothly accelerate the air in a non turbulent fashion into the 50mm throttle body.
Dormouse
05-01-2003, 04:50
Max,
Stu's is 1.4 is the vacuum developed in the same ratio as bore volume? i.e will a 2.0 NA pull 2/1.4 more gas volume than the 1.4?
Neat trick on the expansion. It's very simelar to how we develop required thrust from rcoket motors nozzles (but at far higher dynamic pressures!)
1% of atmos? as in 1% of 14.7 psi? or am i getting confused here? Isn't that only work about 1/2 a bhp at max revs in a 2.0L?
Cheers
Dor.
Originally posted by max_torque
A normally aspirated 2.0 litre engine at wide open throttle, and making 100% vol eff at peak power, with a plenum temp of 25 degc will be pulling 0.136 Kg/s of air.
In a 50mm pipe the dymanic component of pressure (the bit that is lost through wall friction and incomplete pressure recovery after compression) will be 1.35 kpa.
Typically when designing an intake system a good target is to aim for around 1 kpa maximum dynamic component. IN this case this will be created by a diameter of 54mm.
Ideally i would aim to have an intake pipe diameter of say 60mm, until 50mm infront of throttle body, where i would have a diameter of say 100mm, with a nice 7degree cone leading from the 60mm to the 100mm, and a nice radiused bellmouth down from the 100mm part that exactly matches up to the 50mm diameter.
This system will then have a low wall loss in the main part, then use the increased diameter of 100mm to decelerate the air, increasing it's pressure by recovering the dynamic componnent (which we know is less than 1 kpa, but worth having as it's 1% of atmospheric) in the nice 7 degree cone, then use the bellmouth to smoothly accelerate the air in a non turbulent fashion into the 50mm throttle body.
Blimey, I understood all that and the principles of manipulating the air pressures thru different pipe bores. fascinating:)
I reckon using off the shelf bits(and trying to keep costs down) I can have a 70mm intake from the filter all the way until where a 90D elbow with a ID of 51 or 48 mm throughout is needed to attach to the throttle body.
max_torque
05-01-2003, 17:45
Theroretically if the manifold volumetric efficency was the same for a 1.4 and a 2.0, then yes it would pull the same ratio of air to it's CC. However i have allowed in my previous calc for the 2.0 16v to pull 100% vol eff at 7000rpm. (which would be good enough for say 75bhp per litre, or 150 net at the flywheel) However a smaller capacity 1.4 8v will not have the same breathing abillity, will make peak power down round about 5000 to 5500rpm and may only make say 95% manifold volumetric efficiency (making say 50 odd bhp per litre). This will lead to a reduced airflow requirement, which in turn requires a smaller bore diameter to produce the same dynamic pressure.
1 kpa dynamic is roughly 1% of atmospheric pressure which is nominally 101.4kPa absolute. Maybe worth only 0.5 bhp, but it's free, and if you get a half here and there they add up eventually!.
Of course for rocket engines your up into the relms of convergent - divergent full expanded suspersonic nozzle theory! tricky enough to nizzle your nozzle!