doubt it m8... you just need to be a good driver!
be my guest and try and beat me though!
Can I use my Westfield?
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Can I use my Westfield?
now now girlies, play nice
Only joking, wouldn,t be a very fair race. You would probrally need 500+hp in a leon to keep up down the strip.
I'm confused having done some sums here - can someone help? Sorry to quote my example again but I hope you'll see where I'm coming from.
At 193.08 g/s MAF reading, my car was showing 6320 rpm and 1940 mb boost.
At 6320 rpm, a 1781 cc engine (without any boost) would shift 6320 x 1781 = 11,255,920cc of air per minute. That's 11.25592 m3 of air /min. Divide by 60 and you get 0.187598667 m3 of air per sec.
Let's assume the air temperature was 5 degrees. At that temperature, a cubic metre of air weighs 1.269kg. So (0.187598667 x 1.269) it's got 0.238062708 kg of air going through per sec = 238.06 g/s.
Now if I take boost into the equation 238.06 g/s x 1940/1013 gives 455.91 g/s of air going through the MAF tube. So what relationship has this got with 193.08 g/s
I was going to dig out the relevant chapter in the book and make myself look clever, but I don't think that would help
One thing I spotted though was that the air in the cylinder isn't at 5'C
TRY and get ur LCR into the 13s first!
I got my old S3 down to 14 dead, may put some Toyo R888 on the leon then. Hope to get the westfield into the high 11's with the new engine.
iv got yoko prada spec 2s on the front.
wen i was last at pod there was an IHI s3 and he could only managed a 13.9
hes a member on here too, think he had a bad day, his pb was 13.6 i think
anyways back to the topic...
I was going to dig out the relevant chapter in the book and make myself look clever, but I don't think that would help
One thing I spotted though was that the air in the cylinder isn't at 5'C
Which book please Phil?
Temperature of the air going through the MAF was about 5degrees,
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Which book please Phil?
Temperature of the air going through the MAF was about 5degrees,
Yes, the temperature of the air through the MAF was 5'C, but you started your calculation by working out the volume of air the engine will consume at 6320rpm, then converting this to the mass of that volume at 5'C - but the volume of air in the cylinder won't be at 5'C, it'll be considerably higher than that...
hmmmm (red nose and big shoe mode honk,honk) :thinks: I would have thought the measured boost pressure would have taken into account the increased air temperature by the time it was taken into the cylinder......
Ok, great thanks to Phil for taking the time to look up Corky Bell for me and having a stab at the calculation. I had two things missing from my calculation.
The first,
I can't believe I overlooked it. x0.5.
Yes, 4 stroke engine. Cams rotate at half the speed of crank. Inlet valves open every other revolution. Only half the air going through the engine. 
Secondly, Volumetric Efficiency. In a perfect engine, the inlet valves would disappear at the moment the induction stroke started and reappear closed a moment before the compression stroke started. In reality the valves prevent the cylinder from drawing the volume of air it is capable of (or really it's at a lower pressure than the air in the inlet manifold) Corky Bell assumed VE at 85%.
If we take my erroneous 455.91 g/s x 0.5 x 0.85 you get 193.76 g/s - bloody close to the 193.08 the maf was reading. Wow, at least I've learned something. No idea how this really relates to Bhp though.
Edit: I suppose this could be useful in calculating the accuracy of mafs? I'll do some calcs against readings at other rpm. If anyone wants to pm me their own range of rpm/actual boost/external temp/maf reading I'll give it a go. I suppose I could build a calculator on excel. (All when I've time).
The first,
I can't believe I overlooked it. x0.5.Yes, 4 stroke engine. Cams rotate at half the speed of crank. Inlet valves open every other revolution.
Only half the air going through the engine. Secondly, Volumetric Efficiency. In a perfect engine, the inlet valves would disappear at the moment the induction stroke started and reappear closed a moment before the compression stroke started. In reality the valves prevent the cylinder from drawing the volume of air it is capable of (or really it's at a lower pressure than the air in the inlet manifold) Corky Bell assumed VE at 85%.
If we take my erroneous 455.91 g/s x 0.5 x 0.85 you get 193.76 g/s - bloody close to the 193.08 the maf was reading. Wow, at least I've learned something. No idea how this really relates to Bhp though.
Edit: I suppose this could be useful in calculating the accuracy of mafs? I'll do some calcs against readings at other rpm. If anyone wants to pm me their own range of rpm/actual boost/external temp/maf reading I'll give it a go. I suppose I could build a calculator on excel. (All when I've time).
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Really?
I think I'd rather go Christmas shopping with the missus or have all my finger nails extracted with pliers instead of calculating that
Am I helping on this thread????
Of course you are Steve. Every court needs a couple of clowns and a fool. As Feel and I have reserved the clown roles............................
Ok, great thanks to Phil for taking the time to look up Corky Bell for me and having a stab at the calculation. I had two things missing from my calculation.
The first,
Yes, 4 stroke engine. Cams rotate at half the speed of crank. Inlet valves open every other revolution.
Secondly, Volumetric Efficiency. In a perfect engine, the inlet valves would disappear at the moment the induction stroke started and reappear closed a moment before the compression stroke started. In reality the valves prevent the cylinder from drawing the volume of air it is capable of (or really it's at a lower pressure than the air in the inlet manifold) Corky Bell assumed VE at 85%.
If we take my erroneous 455.91 g/s x 0.5 x 0.85 you get 193.76 g/s - bloody close to the 193.08 the maf was reading. Wow, at least I've learned something. No idea how this really relates to Bhp though.
Edit: I suppose this could be useful in calculating the accuracy of mafs? I'll do some calcs against readings at other rpm. If anyone wants to pm me their own range of rpm/actual boost/external temp/maf reading I'll give it a go. I suppose I could build a calculator on excel. (All when I've time).
Who the feck is Corky Bell.
Is the factor of 0.85 an industry standard or was it conveniently choosen to reach the desired figs. And yes i am a facts and figures nerd just like you guys.
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