Congratulations to vtecmec for winning May/June's Lude Of The Month, with his DIY Turbo BB1 build.
>>> Click Here For Profile <<<
>>> Click Here For Profile <<<
ram air geekery
ram air geekery
So,
The geek in me escaped this evening and I did some maths on the 'ram air' effect
Obviously to get the numbers there is a link between engine speed and car speed, it also takes no account of drag in the air intake path or losses from the air filter but I've got the following;
If you have an M2B4 box with 215/45/17's you'd have a 5th gear of circa 20mph / 1000rpm
for every 1000 rpm a H22 needs 2.157 m^3 / min of air.
a cold air intake of 72mm ID can provide 2.39 m^3 / min of air in 5th gear which gives approx +13% more airflow than the motor needs so essentially it's adding a little extra pressure to the air intake so it's doing what it's supposed to eventually. This bore only offers benefit in 5th gear, it cannot provide sufficient flow in the lower gears.
Continuing with the above 'car' (215/45/17's, M2B4 box) and changing the air feed bore you get the following numbers
80mm ID
1st gear 33% of air required
2nd gear 56% of air required
3rd gear 80% of air required
4th gear 106% of air required
5th gear 139% of air required
90mm ID
1st gear 42% of air required
2nd gear 71% of air required
3rd gear 102% of air required
4th gear 134% of air required
5th gear 176% of air required
100mm ID
1st gear 52% of air required
2nd gear 90% of air required
3rd gear 126% of air required
4th gear 166% of air required
5th gear 218% of air required
110mm ID
1st gear 63% of air required
2nd gear 109% of air required
3rd gear 152% of air required
4th gear 200% of air required
5th gear 264% of air required
Think of these numbers what you will, to me for a car used as a road car to get any benefit from the ram air effect the intake needs to be 100mm ID or greater to see some benefit at the top end of 3rd gear.
The geek in me escaped this evening and I did some maths on the 'ram air' effect
Obviously to get the numbers there is a link between engine speed and car speed, it also takes no account of drag in the air intake path or losses from the air filter but I've got the following;
If you have an M2B4 box with 215/45/17's you'd have a 5th gear of circa 20mph / 1000rpm
for every 1000 rpm a H22 needs 2.157 m^3 / min of air.
a cold air intake of 72mm ID can provide 2.39 m^3 / min of air in 5th gear which gives approx +13% more airflow than the motor needs so essentially it's adding a little extra pressure to the air intake so it's doing what it's supposed to eventually. This bore only offers benefit in 5th gear, it cannot provide sufficient flow in the lower gears.
Continuing with the above 'car' (215/45/17's, M2B4 box) and changing the air feed bore you get the following numbers
80mm ID
1st gear 33% of air required
2nd gear 56% of air required
3rd gear 80% of air required
4th gear 106% of air required
5th gear 139% of air required
90mm ID
1st gear 42% of air required
2nd gear 71% of air required
3rd gear 102% of air required
4th gear 134% of air required
5th gear 176% of air required
100mm ID
1st gear 52% of air required
2nd gear 90% of air required
3rd gear 126% of air required
4th gear 166% of air required
5th gear 218% of air required
110mm ID
1st gear 63% of air required
2nd gear 109% of air required
3rd gear 152% of air required
4th gear 200% of air required
5th gear 264% of air required
Think of these numbers what you will, to me for a car used as a road car to get any benefit from the ram air effect the intake needs to be 100mm ID or greater to see some benefit at the top end of 3rd gear.
PAW rebuilt 98 prelude 228bhp & 171lb/ft R.I.P.
PAW rebuilt 01 ATR 238bhp & 164lb/ft sold
Monte Carlo Blue 02 S2K
PAW rebuilt 01 ATR 238bhp & 164lb/ft sold
Monte Carlo Blue 02 S2K
- mercutio
- LotM Winner
- Posts: 14958
- Joined: Sun Aug 08, 2010 8:45 pm
- My Generation: 5G
- Location: Sunny Manchester
- Has thanked: 1 time
- Been thanked: 3 times
- Contact:
well there is no ram effect for the standard intake as its taken from behind a cover in the front wheel well
bristol_bb4 wrote:ahhh a 5th gen, i love 5th gens
Dino wrote:I loves the 5th gen really.... just dont quote me on it...
4thgenphil wrote:Mines 4 1/4 unches mate, sorry
http://www.ludegeneration.co.uk/profile ... -t618.html
- NafemanNathan
- LotM Winner
- Posts: 20144
- Joined: Sun Aug 08, 2010 9:37 pm
- My Generation: 0G
- Location: Yeovil, Somerset
- Has thanked: 8 times
- Been thanked: 122 times
- NafemanNathan
- LotM Winner
- Posts: 20144
- Joined: Sun Aug 08, 2010 9:37 pm
- My Generation: 0G
- Location: Yeovil, Somerset
- Has thanked: 8 times
- Been thanked: 122 times
- NafemanNathan
- LotM Winner
- Posts: 20144
- Joined: Sun Aug 08, 2010 9:37 pm
- My Generation: 0G
- Location: Yeovil, Somerset
- Has thanked: 8 times
- Been thanked: 122 times