BHP limit of........
Phil, where the f**k did you get the 8 greys idea from??
02-02-2005, 04:09 PM
#7
Jeebus
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Steve, does doubling the power output of an engine specifically require double the amount of fuel? 
At a guess the curve of fuel input to power produced isn't linear!
At a guess the curve of fuel input to power produced isn't linear!
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02-02-2005, 04:10 PM
#8
Mike, is there some reason then why on the cossie 8 injector setup you have to run massively less duration on the extra 4 injectors, as i fail to see why they are only going to supply half as much fuel as the existing 4????
Your AFR going from 400bhp to 700bhp is only going to shift by 20% absolute max i should think? (ie from 12.5 to perhaps 10.5, but even that seems a little rich to me)
Your AFR going from 400bhp to 700bhp is only going to shift by 20% absolute max i should think? (ie from 12.5 to perhaps 10.5, but even that seems a little rich to me)
02-02-2005, 04:13 PM
#9
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Chip...you have proved you dont know everything 
It certainly aint good for double!!!!I am hoping that 8 greys which ='s around 1000cc x 4 is good enuff for my build........700bhp is the max i am going for but if the limit is 675bhp then that will be ok as the injectors wont be working on max hardly at all
It certainly aint good for double!!!!I am hoping that 8 greys which ='s around 1000cc x 4 is good enuff for my build........700bhp is the max i am going for but if the limit is 675bhp then that will be ok as the injectors wont be working on max hardly at all
02-02-2005, 04:16 PM
#11
DEYTUKURJERBS
Jim/Phil- You say that, but give me the technical reason why an engine would use more than double the fuel to create double the power?
Its about keeping the AFR safe, and like chip said, thats a big change mike talks about there, its not like 400bhp cars can run super lean is it.
Im not feeling dead clever today, but looks like some people think they are, so go for it with the explanation
Its about keeping the AFR safe, and like chip said, thats a big change mike talks about there, its not like 400bhp cars can run super lean is it.
Im not feeling dead clever today, but looks like some people think they are, so go for it with the explanation
02-02-2005, 04:16 PM
#12
Mike, actually ignore that, ive answered my own question.
If you need 20% richer AFR, then that means that 40% of the extra fuel is accounted for straight away, so that makes sense.
The thing is though of course, that it depends on what engine spec it is, as if its a big CC motor on a very efficient turbo you wont need a different AFR, so my original comment about it being near double would be correct, but its you are battling massively high intake temps and trying to Det surpress with extra fuel then you would get a far smaller yield.
If you need 20% richer AFR, then that means that 40% of the extra fuel is accounted for straight away, so that makes sense.
The thing is though of course, that it depends on what engine spec it is, as if its a big CC motor on a very efficient turbo you wont need a different AFR, so my original comment about it being near double would be correct, but its you are battling massively high intake temps and trying to Det surpress with extra fuel then you would get a far smaller yield.
02-02-2005, 04:22 PM
#14
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Steve, the engine becomes less efficient the more power you squeeze out of it.
Also, you are inevitably fighting against a bigger turbo whilst decreasing the AFR (i.e. run a richer fuel mixture) to keep the EGTs lower and the whole lot at a safe temperature.
Thats how I see it anyway!
(Edited as it read the wrong way round with regards to the AFR)
Also, you are inevitably fighting against a bigger turbo whilst decreasing the AFR (i.e. run a richer fuel mixture) to keep the EGTs lower and the whole lot at a safe temperature.
Thats how I see it anyway!
(Edited as it read the wrong way round with regards to the AFR)
02-02-2005, 04:22 PM
#15
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I don't know either Steve but I guess it's comparible to a 300 bhp car that weighs 750kg is not twice as quick as a 1500 kg car with 300bhp, and a 600bhp car weighing the same as a 300bhp car is not exactly twice as fast 
02-02-2005, 04:26 PM
#16
No it really is like me and Phil have been saying, the reason for less power is people are assuming (with a lot of justification) that you need to be running richer.
If you were using 8 greys on a custom 4 cylinder block with 3 litres, and a GT42 turbo you would be able to get 800+ out of them as you could stick to 12:1 AFR
If you were using 8 greys on a custom 4 cylinder block with 3 litres, and a GT42 turbo you would be able to get 800+ out of them as you could stick to 12:1 AFR
02-02-2005, 04:44 PM
#17
Its actually impossible to calculate. Is that a better answer? 
If the engine in questions VE and BSFC remained the same and thus teh engine required exactly double the airflow to make double the power, then you could get around double the power from double the fuel and air, presuming the afr remained the same.
However, since they will likely not be exactly as before due to laregr heads, turbos etc, we are likely to require more than twice the air to make twice the power, and also likely to run richer etc etc.. all using more fuel.
The law of diminishing returns applies quite strongly when dealing with almost all aspects of horsepower..lol
"How fast can you afford to go sir?"
Thats the only question of any relevance
If the engine in questions VE and BSFC remained the same and thus teh engine required exactly double the airflow to make double the power, then you could get around double the power from double the fuel and air, presuming the afr remained the same.
However, since they will likely not be exactly as before due to laregr heads, turbos etc, we are likely to require more than twice the air to make twice the power, and also likely to run richer etc etc.. all using more fuel.
The law of diminishing returns applies quite strongly when dealing with almost all aspects of horsepower..lol
"How fast can you afford to go sir?"
Thats the only question of any relevance
02-02-2005, 09:58 PM
#23
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No Stu i think 8 greys will go in and lets see if they can handle the assault..i know for a fact they would be not enuff for 700bhp but 650-680bhp we nearly there IMO...Only time will tell....i may have to go 4 x 1200cc.
?
03-02-2005, 08:46 AM
#27
I really am positive that on a low compression bottom end with a decent sized intercooler running a GT42R or something else very unstressed that you could quite happily run well over 700bhp on a set of 8 greys as you wouldnt need a mega low AFR in order to keep it in one piece.
03-02-2005, 04:39 PM
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Mike i wondered if anyone actually had tested them on a proper BHP build 
I know they are no good for 700bhp but 680bhp possibly...wanted confirmation thats all
I know they are no good for 700bhp but 680bhp possibly...wanted confirmation thats all
03-02-2005, 04:46 PM
#30
Norris Motorsport
LOL at this post!!! Made me smile anyway!!
800bhp is more than possible on 8 greys. Thats a fact!!!
Where on earth this 675bhp figure comes from is beyond me?
800bhp is more than possible on 8 greys. Thats a fact!!!
Where on earth this 675bhp figure comes from is beyond me?
03-02-2005, 04:54 PM
#31
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Karl did you ever own the game "Simon says"?...I feel you still use it to come out with your quotes.
On a YB at std fuel pressure you are at best gonna get 680bhp....on a single 044 pump about 600bhp aswell pushing it hard.
On a YB at std fuel pressure you are at best gonna get 680bhp....on a single 044 pump about 600bhp aswell pushing it hard.
03-02-2005, 04:59 PM
#33
Phil, 680bhp on what spec engine?
Perfectly possible to go WELL past that on a correctly specced YB on 8 greys, nice low temp induction from a gt42r and big intercooler, and very low CR, no problem at all going past 680.
In order for it to only make 680 at standard fuel pressure you would be down into single figure AFR i should think (i havent bothered to do the calcs)
700bhp is only (lol @ only) about 65-70 lbs per min of air.
Perfectly possible to go WELL past that on a correctly specced YB on 8 greys, nice low temp induction from a gt42r and big intercooler, and very low CR, no problem at all going past 680.
In order for it to only make 680 at standard fuel pressure you would be down into single figure AFR i should think (i havent bothered to do the calcs)
700bhp is only (lol @ only) about 65-70 lbs per min of air.
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