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 8604 Posts Member #: 573 Formerly Axel Podland |
15th Nov, 2006 at 01:41:22pm
Got bored with work this morning so decided to try and compare cam options.
Edited by Paul S on 15th Nov, 2006. Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
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 12307 Posts Member #: 565 Carlos Fandango Burnham-on-Crouch, Essex |
15th Nov, 2006 at 02:10:52pm
not much overlap on the SW5!! On 28th Aug, 2011 Kean said:
At the risk of being sigged... Joe, do you have a photo of your tool? http://www.turbominis.co.uk/forums/index.p...9064&lastpost=1 https://joe1977.imgbb.com/ |
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8604 Posts Member #: 573 Formerly Axel Podland |
15th Nov, 2006 at 02:19:40pm
On 15th of Nov, 2006 at 02:10pm mini13 said:
not much overlap on the SW5!! That would normally be good for a turbo, but I think the exhaust opens too late, which I think would hurt bottom end response. I like the look of the MD274, but it is probably a bit radical for my road 998 turbo. Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
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Site Admin  15300 Posts Member #: 337 Fearless Tom Fenton, Avon Park 2007 & 2008 class D winner & TM legend. |
15th Nov, 2006 at 04:19:36pm
Good stuff Axel, if you have some of the cams to hand and a DTI you could physically measure lift at all degrees, taking this into Excel will produce a "best fit curve" which I found to usually be 6th order polynomial. This then allows you to integrate the area underneath the curve to get a "total valve area" which is very interesting to look at when comparing the profiles.
On 29th Nov, 2016 madmk1 said:
On 28th Nov, 2016 Rob Gavin said:
I refuse to pay for anything else Like fuel 😂😂 |
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8604 Posts Member #: 573 Formerly Axel Podland |
15th Nov, 2006 at 04:27:00pm
On 15th of Nov, 2006 at 04:19pm Tom Fenton said:
Good stuff Axel, if you have some of the cams to hand and a DTI you could physically measure lift at all degrees, taking this into Excel will produce a "best fit curve" which I found to usually be 6th order polynomial. This then allows you to integrate the area underneath the curve to get a "total valve area" which is very interesting to look at when comparing the profiles. Good idea Tom if I had the cams to hand and the time. I've used a percentage sine curve to represent the ramps between the published points but it is probable that some cams accelerate the valve quicker than others giving more area under the curve. I think this is the best way to look at the published data. Can you integrate a 6th order polynomial then Tom? I've forgotten how! Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
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Site Admin 15300 Posts Member #: 337 Fearless Tom Fenton, Avon Park 2007 & 2008 class D winner & TM legend. |
15th Nov, 2006 at 04:32:25pm
I could integrate one about 4 years ago when I wrote my dissertation on the subject! Whether I could now I don't know, although from memory I don't think its actually that difficult.
On 29th Nov, 2016 madmk1 said:
On 28th Nov, 2016 Rob Gavin said:
I refuse to pay for anything else Like fuel 😂😂 |
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5795 Posts Member #: 80 AFRacing LTD Newbury, Berks |
15th Nov, 2006 at 05:37:30pm
Tom thats the only real way to do it...
AlexF |
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8604 Posts Member #: 573 Formerly Axel Podland |
15th Nov, 2006 at 05:45:54pm
I think that in a road going Turbo application there is more to it than the area under the curve.
Edited by Paul S on 15th Nov, 2006. Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
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 2742 Posts Member #: 637 Post Whore Hertfordshire |
15th Nov, 2006 at 06:05:33pm
how do you open the file??
My build thread..
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8604 Posts Member #: 573 Formerly Axel Podland |
15th Nov, 2006 at 06:13:49pm
It should open with Adobe PDF Viewer.
Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
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12307 Posts Member #: 565 Carlos Fandango Burnham-on-Crouch, Essex |
15th Nov, 2006 at 06:17:48pm
i'd be interested to see a 266 and 286 on there, well a 266 inlet and 286 exhaust really, On 28th Aug, 2011 Kean said:
At the risk of being sigged... Joe, do you have a photo of your tool? http://www.turbominis.co.uk/forums/index.p...9064&lastpost=1 https://joe1977.imgbb.com/ |
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8604 Posts Member #: 573 Formerly Axel Podland |
15th Nov, 2006 at 06:28:53pm
On 15th of Nov, 2006 at 06:17pm mini13 said:
i'd be interested to see a 266 and 286 on there, well a 266 inlet and 286 exhaust really, Give me the figures and I'll add them. Also tell me what you wish to compare with eg PH2, MGM etc Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
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3588 Posts Member #: 655 Post Whore Northern Ireland |
15th Nov, 2006 at 06:33:33pm
On 15th of Nov, 2006 at 02:19pm Axel said:
On 15th of Nov, 2006 at 02:10pm mini13 said:
not much overlap on the SW5!! That would normally be good for a turbo, but I think the exhaust opens too late, which I think would hurt bottom end response. I like the look of the MD274, but it is probably a bit radical for my road 998 turbo. SW5 worked very very well in mine. Incredibly torquey virtually from idle, and makes good power all the way to 7000rpm+ I'm surprised to see how much overlap the Ph2 cam has on that graph. Out of interest. Has anyone ever measured exhaust gas back pressure on their setups ? and comapred inlet/exhaust pressure ? That would be an indicator, of how big you could go, with the overlap. 9.85 @ 145mph
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 6745 Posts Member #: 828 Post Whore uranus |
16th Nov, 2006 at 07:54:52am
On 15th of Nov, 2006 at 04:27pm Axel said:
On 15th of Nov, 2006 at 04:19pm Tom Fenton said:
Good stuff Axel, if you have some of the cams to hand and a DTI you could physically measure lift at all degrees, taking this into Excel will produce a "best fit curve" which I found to usually be 6th order polynomial. This then allows you to integrate the area underneath the curve to get a "total valve area" which is very interesting to look at when comparing the profiles. Good idea Tom if I had the cams to hand and the time. I've used a percentage sine curve to represent the ramps between the published points but it is probable that some cams accelerate the valve quicker than others giving more area under the curve. I think this is the best way to look at the published data. Can you integrate a 6th order polynomial then Tom? I've forgotten how! i have graphed out a lot of cams over the years ,its definately true to say that the ramps can vary a lot from say 20 degrees seat to .050 lift up to 35 to 40 degrees for the same event ,, if you can get the seat timnig ,and the .050 lift timing axel ,that would tell you the ramp dimensions , unfortunately in the uk this isnt normally given ,hence my graphing over the years , . i graphed out 4 astra 1300 cams at one time doing some research , and found that they varied so much it was like comparing rally and fast rd , specially lsa . ive found that cams i have had made by piper to be quite good on the regularity of duration front . generally the higher the technology of the ramp design ,the greater the acceleration rate ,and so the seat to .050 time gets shorter , i think the shortest i know of was 22 degrees but im sure there must be some about now that are shorter ,but maybe a bit short lived . average is 28 degrees ish . oh also the ramp at lift is sometimes v diff to the ramp at close to keep the tappet quiet . regards robert Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM |
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12307 Posts Member #: 565 Carlos Fandango Burnham-on-Crouch, Essex |
25th Nov, 2008 at 09:26:08am
I've just measured a PH 2 cam.... On 28th Aug, 2011 Kean said:
At the risk of being sigged... Joe, do you have a photo of your tool? http://www.turbominis.co.uk/forums/index.p...9064&lastpost=1 https://joe1977.imgbb.com/ |
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8604 Posts Member #: 573 Formerly Axel Podland |
25th Nov, 2008 at 05:09:59pm
And ???? Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
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 6274 Posts Member #: 509 Post Whore Isle of Man |
25th Nov, 2008 at 05:57:35pm
On 15th Nov, 2006 stevieturbo said:
Out of interest. Has anyone ever measured exhaust gas back pressure on their setups ? and comapred inlet/exhaust pressure ? That would be an indicator, of how big you could go, with the overlap. A certain someone that is now banned from TM apparently supposedly allegedgely went down this route, but during an period he came back and deleted all the posts about it. "Turbo's make torque, and torque makes fun"
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12307 Posts Member #: 565 Carlos Fandango Burnham-on-Crouch, Essex |
25th Nov, 2008 at 07:18:32pm
I need to re check this really but here oit is anyway, I timed the cam at 109 deg atdc but in the graph it looks later than that (probably due to taking a reading every 5 degrees). also there are a couple of bumps, i may have made a typo entering the figures.
Edited by Joe C on 25th Nov, 2008. On 28th Aug, 2011 Kean said:
At the risk of being sigged... Joe, do you have a photo of your tool? http://www.turbominis.co.uk/forums/index.p...9064&lastpost=1 https://joe1977.imgbb.com/ |
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 85 Posts Member #: 2234 Advanced Member Palm Beach Gardens, Florida |
26th Nov, 2008 at 12:35:00pm
Looking at cam displacement graphs just isn't very informative. When you get more data points then you will be able to get accurate velocity, acceleration, and jerk plots. I am concerned that sinusoidal curves fit to a few data points will not be accurate enough, maybe for the three-arc cam profiles but not for a polynomial fit profile. |
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8604 Posts Member #: 573 Formerly Axel Podland |
26th Nov, 2008 at 12:45:15pm
On 26th Nov, 2008 scooperman said:
Looking at cam displacement graphs just isn't very informative. When you get more data points then you will be able to get accurate velocity, acceleration, and jerk plots. I am concerned that sinusoidal curves fit to a few data points will not be accurate enough, maybe for the three-arc cam profiles but not for a polynomial fit profile. You know that, I know that, we all know that. If all you have is the published timing figures, then this is a graphical method of interpreting them. When I posted this two years ago, it was just intended as a way of comparing cams before you bought one. Why is everyone trying to be a smart arse, that's my job. Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
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 3692 Posts Member #: 1833 Formally mini_majic Auckland, New Zealand |
26th Nov, 2008 at 07:04:10pm
On 26th Nov, 2008 scooperman said:
jerk plots. hehehe |
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12307 Posts Member #: 565 Carlos Fandango Burnham-on-Crouch, Essex |
26th Nov, 2008 at 07:28:37pm
jerk.... On 28th Aug, 2011 Kean said:
At the risk of being sigged... Joe, do you have a photo of your tool? http://www.turbominis.co.uk/forums/index.p...9064&lastpost=1 https://joe1977.imgbb.com/ |
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