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+--- Thread: Performance drop off (/showthread.php?tid=20222)
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RE: Performance drop off - Dum-Dum - 10-01-2014
(08-01-2014, 03:51 PM)zx_volcane Wrote: adding a few 10s of psi down the inlet isn't going to increase peak cylinder pressures significantly over what they are already, ie stupidly high.Doesn't work like that, 10psi boost dosen't add 10psi to the peak cylinder pressure, its 10psi multiplied by the compression ratio (23:1) ish so you actually add about 250psi to the pre combustion peak pressure.
(09-01-2014, 11:13 AM)jammapic Wrote: You tend to lose around 1.5% peak bhp and torque for every 5*c of extra inlet temp.The factor the Amerians always talk about is 10% for every 100*F. Suppose its about the same difference really.
However 10% power loss on a 170bhp DTurbo is almost 20bhp
RE: Performance drop off - padge - 10-01-2014
that is cool!
RE: Performance drop off - ste91 - 10-01-2014
I'm starting to wonder about the accuracy of some of your boost gauges, you're not using those £20 ones from halfords are you lol?
RE: Performance drop off - zx_volcane - 10-01-2014
(10-01-2014, 05:01 PM)Dum-Dum Wrote:(08-01-2014, 03:51 PM)zx_volcane Wrote: adding a few 10s of psi down the inlet isn't going to increase peak cylinder pressures significantly over what they are already, ie stupidly high.Doesn't work like that, 10psi boost dosen't add 10psi to the peak cylinder pressure, its 10psi multiplied by the compression ratio (23:1) ish so you actually add about 250psi to the pre combustion peak pressure.
I understand this, but I'd expect peak cylinder pressures during combustion to be in the 1000s of psi
compared to running too much advance which will raise them significantly
or combining that air with enough fuel to burn it all which again would increase it significantly
RE: Performance drop off - Dum-Dum - 10-01-2014
(10-01-2014, 05:28 PM)zx_volcane Wrote:(10-01-2014, 05:01 PM)Dum-Dum Wrote:(08-01-2014, 03:51 PM)zx_volcane Wrote: adding a few 10s of psi down the inlet isn't going to increase peak cylinder pressures significantly over what they are already, ie stupidly high.Doesn't work like that, 10psi boost dosen't add 10psi to the peak cylinder pressure, its 10psi multiplied by the compression ratio (23:1) ish so you actually add about 250psi to the pre combustion peak pressure.
I understand this, but I'd expect peak cylinder pressures during combustion to be in the 1000s of psi
Oh yeah, totally. That said can they really be in the 1000s of psi as otherwise the injection pumps wouldn't be able to inject as they only run at a little over 100bar or 1500psi and if the cylinder pressure was greater than the fuel then you would get no injection.
RE: Performance drop off - zx_volcane - 10-01-2014
(10-01-2014, 05:45 PM)Dum-Dum Wrote: Oh yeah, totally. That said can they really be in the 1000s of psi as otherwise the injection pumps wouldn't be able to inject as they only run at a little over 100bar or 1500psi and if the cylinder pressure was greater than the fuel then you would get no injection.
don't forget fuel is injected during the compression stroke, peak cylinder pressure will be made on the power stroke
also break pressures for our injectors are 175bar
RE: Performance drop off - Dum-Dum - 10-01-2014
175 for bosch, lower for lucas iirc
RE: Performance drop off - LewisG306 - 10-01-2014
(10-01-2014, 05:00 PM)Ruan Wrote: http://www.youtube.com/watch?v=v9Z5Hd0yqvg
I mean like this!
That's awesome , who wouldn't wanna blow some buildings up?
It's just exactly the same story though isn't it? That will be a lot bigger with it being like a 6 liter engine and they probably throwing in like a 200hp worth of gas lol , crazy yanks...