Valve lift vs. port flow and cam selection

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Re: Valve lift vs. port flow and cam selection

Post by PRH »

PRH wrote: ↑ My responses were centered around the idea that you can’t come up with a race winning cam selection without flow data.
That's a strawman argument. No one said that.
The comment below is the only reason I responded to this thread in the first place.
It sure sounds like he’s saying you’d have no idea where to begin on cam selection without flow data.
If you dont have any numbers how in the world to you even know what to grind?
Somewhat handy with a die grinder.
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Re: Valve lift vs. port flow and cam selection

Post by Steve.k »

Without flow numbers your guessing. In the above combos for the street version not going matter much if your slightly off. In a all out setup you can never have enough info i figure. Have helped alot of guys take their engine data including flow numbers and just added a custom cam other then the one they guessed from book and gained a ton. Without flow data i doubt we would’ve seen much improvement.
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Re: Valve lift vs. port flow and cam selection

Post by PRH »

I wonder if the top tier racing teams ever try more than one cam.

I mean....... surely they have all the pertinent data....... so, one and done?
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Re: Valve lift vs. port flow and cam selection

Post by cjperformance »

PRH wrote: Tue Jan 28, 2020 5:55 pm
If you dont have any numbers how in the world to you even know what to grind?
Thats an odd question, Its pretty rare/unlikely that in a high effort build you would have no numbers at all. I cant see anyone building anything competitive not having any numbers at all. As has been said time again, numbers are not everything, but are even if just looking at a max number a good guide to port efficiency and anyone building anything decent is going to have a look at this aspect, so forgetting wringing every last drop out of a combo , choosing cam specs with no head numbers at all to work from is not that difficult. With some experience most guys have an idea of what general spec gives what result. If you only have gearing, CR and intended use to work from its pretty easy to grind something that works pretty well or infact really well.
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Re: Valve lift vs. port flow and cam selection

Post by PRH »

so forgetting wringing every last drop out of a combo , choosing cam specs with no head numbers at all to work from is not that difficult. With some experience most guys have an idea of what general spec gives what result. If you only have gearing, CR and intended use to work from its pretty easy to grind something that works pretty well or infact really well.
That’s all I’ve been saying.
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Re: Valve lift vs. port flow and cam selection

Post by Steve.k »

PRH wrote: Tue Jan 28, 2020 6:05 pm I wonder if the top tier racing teams ever try more than one cam.

I mean....... surely they have all the pertinent data....... so, one and done?
Oh im sure they try a ton of cams. But their budget is a little heftier than most. I dont think anyone saying thats all you need! We are saying it’s important piece of puzzle.
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Re: Valve lift vs. port flow and cam selection

Post by CamKing »

Steve.k wrote: Tue Jan 28, 2020 8:23 pm
PRH wrote: Tue Jan 28, 2020 6:05 pm I wonder if the top tier racing teams ever try more than one cam.

I mean....... surely they have all the pertinent data....... so, one and done?
Oh im sure they try a ton of cams. But their budget is a little heftier than most. I dont think anyone saying thats all you need! We are saying it’s important piece of puzzle.
Not as many as you think.
When IndyCar went to NA engines, my cams were in over 80% of the field from 1997-2002, and powered 3 Indy 500 champions. Over those 6 years, I think we only made 6 or 7 different cam designs, and 2 or 3 of them, were because of rule changes to the RPM limit, and engine size. When Montoya won the 500, the cams in his car were not the latest designs, but they were close enough in power to still be successful.
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Re: Valve lift vs. port flow and cam selection

Post by Steve.k »

Oh yes and there’s been a hell of a change in head flow from 1984 till now thats for sure.
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Re: Valve lift vs. port flow and cam selection

Post by SpeierRacingHeads »

Does CFD tell you what it flows?
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Re: Valve lift vs. port flow and cam selection

Post by Walter R. Malik »

CamKing wrote: Tue Jan 28, 2020 2:42 pm
PRH wrote: Tue Jan 28, 2020 2:21 pm Great response!!

But...... does that mean when someone calls without flow data...... you don’t sell them a cam?
I fill in the picture as best I can.
If they don't have port flow data, I have a data base with flow data for a bunch of different heads, ported by different companies.
If he tells me they're a 10X head ported by Chapman, I have the data.
If he tells me, they were hand ported by some guy in his garage, I have to take an educated guess, but it's still a guess.
It is good to hear someone "tell it as it is", in the world of actualities and a million people who only build 2 or 3 engines in their lifetime.
Even with having flow numbers, you're guessing but, you can give a more educated guess.
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Re: Valve lift vs. port flow and cam selection

Post by BlitzA64 »

It is good to hear someone "tell it as it is", in the world of actualities and a million people who only build 2 or 3 engines in their lifetime.
Even with having flow numbers, you're guessing but, you can give a more educated guess.
Yep, pretty much any engine builder is dealing with a list of compromises not to mention vehicle set up, driver and flawed data that may be received. The latest and greatest can often be slower that the outdated when factored in with the above and driving style is a big one. Before the data logger days I've been guilty of believing flawed data that has hindered my program. The more CORRECT data the better, but flawed data can shoot you in the foot real quick.
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Re: Valve lift vs. port flow and cam selection

Post by bob460 »

Not as many as you think.
When IndyCar went to NA engines, my cams were in over 80% of the field from 1997-2002, and powered 3 Indy 500 champions. Over those 6 years, I think we only made 6 or 7 different cam designs, and 2 or 3 of them, were because of rule changes to the RPM limit, and engine size. When Montoya won the 500, the cams in his car were not the latest designs, but they were close enough in power to still be successful.

How many builders do you do cams for the EMC?
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