Do you REALLY have Torque, or you have been told you do?
#32
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Originally Posted by Jean
..The air measurement and its relation to torque has been discussed before, it is the BSAC that I sometimes refer to, for our engines, about 8.5 hp/lb/min of air..
So if somebody's 993TT engine is from the worst end of this scale, lets say only 9.5 hp / lb/min and
your OBD MAF measurement gives max. reading 424 g/s which is 1526 kg/h and 56.1 lb/min that makes the very familiar horsepower reading : 533 hp!
That is also the reading what RS Tuning has been said they have on their tuned 993TTs.
This is also the same value what I have got from my tuned 993TT (with the stock MAF).
And it is also the max value of the stock 993TT MAF which it can be measured.
So as speaking in Jean's words with all respect : "Do you really have horsepower, or you have been told you do"
![Smilie](https://rennlist.com/forums/images/smilies/smile.gif)
So if you have the tuned 993TT with MAF based Motronic and "over 550hp", do that simple and cheap powertest with OBD scanner and tell us results.
![Cheers](https://rennlist.com/forums/images/smilies/beerchug.gif)
#33
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Originally Posted by js-911
That 8.5 hp / lb/min is quite low reading. I have heard this value is normally between 9.5 and 10.5.
So if somebody's 993TT engine is from the worst end of this scale, lets say only 9.5 hp / lb/min and
your OBD MAF measurement gives max. reading 424 g/s which is 1526 kg/h and 56.1 lb/min that makes the very familiar horsepower reading : 533 hp!
That is also the reading what RS Tuning has been said they have on their tuned 993TTs.
This is also the same value what I have got from my tuned 993TT (with the stock MAF).
And it is also the max value of the stock 993TT MAF which it can be measured.
So as speaking in Jean's words with all respect : "Do you really have horsepower, or you have been told you do"![Smilie](https://rennlist.com/forums/images/smilies/smile.gif)
So if you have the tuned 993TT with MAF based Motronic and "over 550hp", do that simple and cheap powertest with OBD scanner and tell us results.
![Cheers](https://rennlist.com/forums/images/smilies/beerchug.gif)
So if somebody's 993TT engine is from the worst end of this scale, lets say only 9.5 hp / lb/min and
your OBD MAF measurement gives max. reading 424 g/s which is 1526 kg/h and 56.1 lb/min that makes the very familiar horsepower reading : 533 hp!
That is also the reading what RS Tuning has been said they have on their tuned 993TTs.
This is also the same value what I have got from my tuned 993TT (with the stock MAF).
And it is also the max value of the stock 993TT MAF which it can be measured.
So as speaking in Jean's words with all respect : "Do you really have horsepower, or you have been told you do"
![Smilie](https://rennlist.com/forums/images/smilies/smile.gif)
So if you have the tuned 993TT with MAF based Motronic and "over 550hp", do that simple and cheap powertest with OBD scanner and tell us results.
![Cheers](https://rennlist.com/forums/images/smilies/beerchug.gif)
K16's I recall push 24 lb/min and K24's push 28 lb/min.
But to be honest - that's in "perfect mode". Real world I have my doubts the K24's are up for the job in the long run.
Anyone got figures for K16/24 hybrids?
#34
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Originally Posted by Rassel
Don't want to open a can of Perkele here, but can dual K24's really produce 56.1 lb/min consistently?..
![Smilie](https://rennlist.com/forums/images/smilies/smile.gif)
![rockon](https://rennlist.com/forums/graemlins/rockon.gif)
Maybe MOD or TB or somebody else can tell more about K24s capability to produce air(=>Torque/Horsepower) by doing this OBD MAF test..
#35
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Originally Posted by js-911
Perkele!
I don't know if dual K24 can produce that amount.. but I promise, dual GT2871R can ![rockon](https://rennlist.com/forums/graemlins/rockon.gif)
![Smilie](https://rennlist.com/forums/images/smilies/smile.gif)
![rockon](https://rennlist.com/forums/graemlins/rockon.gif)
![EEK!](https://rennlist.com/forums/images/smilies/eek.gif)
Don't want to go OT - but your internal mods I guess are quite extensive..
#36
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js
A stock 993TT will give you about 8.5 hp/lb, a 996TT will get you to 9.3 according to engine dyno datalogs, it is not hearsay.
As far as the MAF, stock MAF will take a 996TT to 490HP, after that you need to "kludge" the calibration, or change to a bigger one.
The K24 turbos that TB and others are using are not K24 compressors, they are much larger hybrids. The 533PS upgrade they have is a bit more than an ECU remap on stock MAF.
A stock 993TT will give you about 8.5 hp/lb, a 996TT will get you to 9.3 according to engine dyno datalogs, it is not hearsay.
As far as the MAF, stock MAF will take a 996TT to 490HP, after that you need to "kludge" the calibration, or change to a bigger one.
The K24 turbos that TB and others are using are not K24 compressors, they are much larger hybrids. The 533PS upgrade they have is a bit more than an ECU remap on stock MAF.
![Smilie](https://rennlist.com/forums/images/smilies/smile.gif)
#37
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Ok, don't want to go too much OT with engine mods..
My point is that everyone can estimate their true horsepower with cheap OBD datalogger.
With your max air flow result (in lb/min), you just multiply that value by 8.5
(or 9 or 9.5 if you have internal mods like head work, cams, twinspark etc)
I like to see others result vs horsepower you have been told you do - there must be correlation in those values or otherwise you have been told BS![Smilie](https://rennlist.com/forums/images/smilies/smile.gif)
This Air Flow measurement comparision should be interesting thing - almost like that popular "times from 60 to 130" -thread..![ducking](https://rennlist.com/forums/graemlins/icon107.gif)
Edited: if your OBD reader gives values in g/s like mine, then use following factors :
1.257 (for 9.5, with very good flow improvement mods)
1.19 (for 9.0, with some improvement)
1.124 (for 8.5, stock engine)
My point is that everyone can estimate their true horsepower with cheap OBD datalogger.
With your max air flow result (in lb/min), you just multiply that value by 8.5
(or 9 or 9.5 if you have internal mods like head work, cams, twinspark etc)
I like to see others result vs horsepower you have been told you do - there must be correlation in those values or otherwise you have been told BS
![Smilie](https://rennlist.com/forums/images/smilies/smile.gif)
This Air Flow measurement comparision should be interesting thing - almost like that popular "times from 60 to 130" -thread..
![ducking](https://rennlist.com/forums/graemlins/icon107.gif)
Edited: if your OBD reader gives values in g/s like mine, then use following factors :
1.257 (for 9.5, with very good flow improvement mods)
1.19 (for 9.0, with some improvement)
1.124 (for 8.5, stock engine)
Last edited by Jussi; 06-12-2007 at 04:59 AM.
#38
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Originally Posted by js-911
Ok, don't want to go too much OT with engine mods..
My point is that everyone can estimate their true horsepower with cheap OBD datalogger.
With your max air flow result (in lb/min), you just multiply that value by 8.5
(or 9 or 9.5 if you have internal mods like head work, cams, twinspark etc)
I like to see others result vs horsepower you have been told you do - there must be correlation in those values or otherwise you have been told BS![Smilie](https://rennlist.com/forums/images/smilies/smile.gif)
This Air Flow measurement comparision should be interesting thing - almost like that popular "times from 60 to 130" -thread..![ducking](https://rennlist.com/forums/graemlins/icon107.gif)
Edited: if your OBD reader gives values in g/s like mine, then use following factors :
1.257 (for 9.5, with very good flow improvement mods)
1.19 (for 9.0, with some improvement)
1.124 (for 8.5, stock engine)
My point is that everyone can estimate their true horsepower with cheap OBD datalogger.
With your max air flow result (in lb/min), you just multiply that value by 8.5
(or 9 or 9.5 if you have internal mods like head work, cams, twinspark etc)
I like to see others result vs horsepower you have been told you do - there must be correlation in those values or otherwise you have been told BS
![Smilie](https://rennlist.com/forums/images/smilies/smile.gif)
This Air Flow measurement comparision should be interesting thing - almost like that popular "times from 60 to 130" -thread..
![ducking](https://rennlist.com/forums/graemlins/icon107.gif)
Edited: if your OBD reader gives values in g/s like mine, then use following factors :
1.257 (for 9.5, with very good flow improvement mods)
1.19 (for 9.0, with some improvement)
1.124 (for 8.5, stock engine)
#39
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Just got this from a Superflow engine dyno site !
Brake specific air consumption (BSAC) is a measure of how many pounds of air it takes to make 1 hp for 1 hour (lb/hp-hr). The lower the number, the better: It should be in the 6s or lower if the carb is set up right; a 5.55 BSAC number is really good. However, because BSAC varies per engine displacement and power level, there isn't any hard and fast "correct" value
If this is right then we are looking at the BSAC from the wrong direction. It is the BSAC number which determines how much power your engine can make out of the mass of air delivered - so it is pretty pointless comparing kg/hr readings as for example my engine may have a BSAC of 6 and only need 1550kg/hr of air to produce say 560hp and another engine may need 1600kg/hr to make the same power due to its inferior set up......
Brake specific air consumption (BSAC) is a measure of how many pounds of air it takes to make 1 hp for 1 hour (lb/hp-hr). The lower the number, the better: It should be in the 6s or lower if the carb is set up right; a 5.55 BSAC number is really good. However, because BSAC varies per engine displacement and power level, there isn't any hard and fast "correct" value
If this is right then we are looking at the BSAC from the wrong direction. It is the BSAC number which determines how much power your engine can make out of the mass of air delivered - so it is pretty pointless comparing kg/hr readings as for example my engine may have a BSAC of 6 and only need 1550kg/hr of air to produce say 560hp and another engine may need 1600kg/hr to make the same power due to its inferior set up......
#40
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TB: don't let these different numbers disturb you - they are the same thing.
I show you a little math:
when I and Jean speak about 9.5hp / 1lb/1min this comes to form
9.5hp/(1lb*60hr) which means that 1/1lb*9.5hp/60hr and invert that and you'll get final form 1lb * 60hr/9.5hp which is 6.3 in that BSAC number.
So, trust me and you can estimate your car's horsepower with measuring MAF value. Factor 8.5 which is for stock 993TT (tested in engine dyno) gives very poor value 7.06 and factor 9.5 gives reasonable value 6.3 which is from my car and tested also in engine dyno.
I have better value because I have headworks, RS cams, TS, custom made large and freeflow exhaust system and also bigger inlet for turbos - only IC is still stock but it is still stock only because of you. You have kept me off from crappy FVD/Cargraphic/etc ICs![bigbye](https://rennlist.com/forums/graemlins/xyxwave.gif)
Addition: you can't measure that 1600kg/h with stock MAF and either that 1550kg/h - these numbers are beyond its limits.
So, only way you can get much bigger horsepower reading from max 1546kg/h value is just because your engine flows better, it has better X hp / 1lb/min value!
If you have super hyper free flow system and it gives you 10.5 hp / 1lb/min then it makes real 596 hp..
..but Jean doesn't like that 10.5 number
I show you a little math:
when I and Jean speak about 9.5hp / 1lb/1min this comes to form
9.5hp/(1lb*60hr) which means that 1/1lb*9.5hp/60hr and invert that and you'll get final form 1lb * 60hr/9.5hp which is 6.3 in that BSAC number.
So, trust me and you can estimate your car's horsepower with measuring MAF value. Factor 8.5 which is for stock 993TT (tested in engine dyno) gives very poor value 7.06 and factor 9.5 gives reasonable value 6.3 which is from my car and tested also in engine dyno.
I have better value because I have headworks, RS cams, TS, custom made large and freeflow exhaust system and also bigger inlet for turbos - only IC is still stock but it is still stock only because of you. You have kept me off from crappy FVD/Cargraphic/etc ICs
![bigbye](https://rennlist.com/forums/graemlins/xyxwave.gif)
Addition: you can't measure that 1600kg/h with stock MAF and either that 1550kg/h - these numbers are beyond its limits.
So, only way you can get much bigger horsepower reading from max 1546kg/h value is just because your engine flows better, it has better X hp / 1lb/min value!
If you have super hyper free flow system and it gives you 10.5 hp / 1lb/min then it makes real 596 hp..
..but Jean doesn't like that 10.5 number
![Smilie](https://rennlist.com/forums/images/smilies/smile.gif)
#41
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The maximum my pressure sensing/low air restriction/No MAF engine could hold at peak HP level is 8.5, dropping from 9.1 at 6K RPMS, so anywhere between 8.5 and 9.1 is reasonable for a modified engine at close to max HP. These are numbers based on engine dyno datalogs. The measurement is quite straightforward.
Todd K. has seen a maximum of 9.3-9.5 on modified 996TTs at peak HP.
This is not relevant to torque calculations on this thread however, as it is HP related.
Todd K. has seen a maximum of 9.3-9.5 on modified 996TTs at peak HP.
This is not relevant to torque calculations on this thread however, as it is HP related.
#42
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Originally Posted by js-911
TB: don't let these different numbers disturb you - they are the same thing.
I show you a little math:
when I and Jean speak about 9.5hp / 1lb/1min this comes to form
9.5hp/(1lb*60hr) which means that 1/1lb*9.5hp/60hr and invert that and you'll get final form 1lb * 60hr/9.5hp which is 6.3 in that BSAC number.
So, trust me and you can estimate your car's horsepower with measuring MAF value. Factor 8.5 which is for stock 993TT (tested in engine dyno) gives very poor value 7.06 and factor 9.5 gives reasonable value 6.3 which is from my car and tested also in engine dyno.
I have better value because I have headworks, RS cams, TS, custom made large and freeflow exhaust system and also bigger inlet for turbos - only IC is still stock but it is still stock only because of you. You have kept me off from crappy FVD/Cargraphic/etc ICs![bigbye](https://rennlist.com/forums/graemlins/xyxwave.gif)
Addition: you can't measure that 1600kg/h with stock MAF and either that 1550kg/h - these numbers are beyond its limits.
So, only way you can get much bigger horsepower reading from max 1546kg/h value is just because your engine flows better, it has better X hp / 1lb/min value!
If you have super hyper free flow system and it gives you 10.5 hp / 1lb/min then it makes real 596 hp..
..but Jean doesn't like that 10.5 number![Smilie](https://rennlist.com/forums/images/smilies/smile.gif)
I show you a little math:
when I and Jean speak about 9.5hp / 1lb/1min this comes to form
9.5hp/(1lb*60hr) which means that 1/1lb*9.5hp/60hr and invert that and you'll get final form 1lb * 60hr/9.5hp which is 6.3 in that BSAC number.
So, trust me and you can estimate your car's horsepower with measuring MAF value. Factor 8.5 which is for stock 993TT (tested in engine dyno) gives very poor value 7.06 and factor 9.5 gives reasonable value 6.3 which is from my car and tested also in engine dyno.
I have better value because I have headworks, RS cams, TS, custom made large and freeflow exhaust system and also bigger inlet for turbos - only IC is still stock but it is still stock only because of you. You have kept me off from crappy FVD/Cargraphic/etc ICs
![bigbye](https://rennlist.com/forums/graemlins/xyxwave.gif)
Addition: you can't measure that 1600kg/h with stock MAF and either that 1550kg/h - these numbers are beyond its limits.
So, only way you can get much bigger horsepower reading from max 1546kg/h value is just because your engine flows better, it has better X hp / 1lb/min value!
If you have super hyper free flow system and it gives you 10.5 hp / 1lb/min then it makes real 596 hp..
..but Jean doesn't like that 10.5 number
![Smilie](https://rennlist.com/forums/images/smilies/smile.gif)
If the max possible (if this is proven due to physical restrictions) flow number is 1546kg/hr then the hp number surely depends on the BSAC number which could be anywhere between 8.5 (giving 483hp) or say 10.5 (giving 596hp)......One only knows the true BSAC number if the true Porsche equivalent power output is known and we all know what a grey area that is
![Roll Eyes (Sarcastic)](https://rennlist.com/forums/images/smilies/rolleyes.gif)
BTW if my maximum flow IS 1546kg/hr then my engine's BSAC is 10.1hp/lb/min so I would expect higher flow numbers than the 1546 unless RS really has worked some magic
![Smilie](https://rennlist.com/forums/images/smilies/smile.gif)
#43
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Originally Posted by TB993tt
I still don't get how you can estimate the hp from a given MAF engine ?
I've been always said you can _estimate_, so it is not exact or absolute true value because everybody's engine, tuned or not, are different (=> X hp / lb/min value is different).
BUT, then we can at least compare these values against each others. Like I have measured that 424g/s and I have about 533hp.
My opinion is that this is very interesting - car physics.
Originally Posted by TB993tt
If the max possible (if this is proven due to physical restrictions) flow number is 1546kg/hr
Originally Posted by TB993tt
BTW if my maximum flow IS 1546kg/hr then my engine's BSAC is 10.1hp/lb/min so I would expect higher flow numbers than the 1546 unless RS really has worked some magic ![Smilie](https://rennlist.com/forums/images/smilies/smile.gif)
![Smilie](https://rennlist.com/forums/images/smilies/smile.gif)
![Smilie](https://rennlist.com/forums/images/smilies/smile.gif)
so first you measure that MAF value and then you have reliable horsepower measurement from (RS) dyno. Now you can estimate this BSAC number or better said, "X hp / lb/min" -value.
For example you have measured that 429g/s value and RS Tuning has dynoed your car and got 562hp. You can now estimate that your engine's flow capacity(also efficiency) is 9.9 hp / lb/min which is very good value !
#44
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Originally Posted by js-911
Lets make this thing right or my way
so first you measure that MAF value and then you have reliable horsepower measurement from (RS) dyno. Now you can estimate this BSAC number or better said, "X hp / lb/min" -value.
For example you have measured that 429g/s value and RS Tuning has dynoed your car and got 562hp. You can now estimate that your engine's flow capacity(also efficiency) is 9.9 hp / lb/min which is very good value !
![Smilie](https://rennlist.com/forums/images/smilies/smile.gif)
so first you measure that MAF value and then you have reliable horsepower measurement from (RS) dyno. Now you can estimate this BSAC number or better said, "X hp / lb/min" -value.
For example you have measured that 429g/s value and RS Tuning has dynoed your car and got 562hp. You can now estimate that your engine's flow capacity(also efficiency) is 9.9 hp / lb/min which is very good value !
What I am saying is doing this is a little pointless. For example if one asked one of the Andial boys who thinks they have 58Xhp to measure theirs then they would doubtlessly come up with a 10.5 or whatever which is a pretty pointless number so the flow rate proves ziltch in this context......
It would be interesting and worthy of discussion however if my car (or others) manage to flow more than the 1546kg/hr number
![Smilie](https://rennlist.com/forums/images/smilies/smile.gif)
#45
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Originally Posted by TB993tt
Yes, of course I understand that I will be able to work out my BSAC after getting the max kg/hr reading from the hammer, but I KNOW mine will be correct.
What I am saying is doing this is a little pointless. For example if one asked one of the Andial boys who thinks they have 58Xhp to measure theirs then they would doubtlessly come up with a 10.5 or whatever which is a pretty pointless number so the flow rate proves ziltch in this context......
It would be interesting and worthy of discussion however if my car (or others) manage to flow more than the 1546kg/hr number![Smilie](https://rennlist.com/forums/images/smilies/smile.gif)
What I am saying is doing this is a little pointless. For example if one asked one of the Andial boys who thinks they have 58Xhp to measure theirs then they would doubtlessly come up with a 10.5 or whatever which is a pretty pointless number so the flow rate proves ziltch in this context......
It would be interesting and worthy of discussion however if my car (or others) manage to flow more than the 1546kg/hr number
![Smilie](https://rennlist.com/forums/images/smilies/smile.gif)
And if you also publish dyno hp reading, then we can make a list from best X hp / lb/min values..
Another point is that if you don't have that dyno proved hp value, you just have previous owner's promise: "it has at least 600hp" then you can test that value with MAF value * 9.5 or whatever would be average values from our dyno proved cars.. That is my original point : "do you really that hp values, or you have just been told you do"