Example(s) of 50* seat reducing flow, but increasing power?

[Stan Weiss]

There will be several who will say "you just didn't get the cam right for the increase in flow" and that will be from ones who have done no testing at all, and even some who never even build any engines at all and just spread info from forum to forum or have been to a seminar or read a book that says so, so it has to be fact that you can't have less flow but more power.

Seems my prediction is coming true.

Randy

Or it could just be a self-fulling prophecy.

Stan

[BILL-C]

Anyone give any thought to how the fuel flow pattern has been changed by the valve seat angle change? How about combustion chamber shrouding? Changing from 45 to 50* seat also needs changes in throat %, top angle, bottom angles, valve shape or at least back cut to get full benefit. 50* seat package seems to require less chamber unshrouding also, which helps to keep cr up. The more i play with 50* seats the more i like them.

[randy331]

The more i play with 50* seats the more i like them.

Those that actually test them seem to like them, those that only flow them tend to not like them.
Enter the 45* vs 50* flowz in a dyno sim program and see what the results say.
But those sims most likely won't match real results.

Randy

[makin chips]

The diminutive of low lift flow and increase in high lift flow when using a 50 degree seat in a race motor makes more power, but the shift in peak port velocity to a higher rpm also raises the rpm of peak TQ and HP.

What???

Rick

The definition of diminutive is "extremely or unusually small" so it makes no sense whatsoever.

'The "extremely small" of low lift flow...'? Yea, that's not going to work.

[Rimmo]

Therefore, I'm going to ask a straight-forward question: Can anyone provide data where...
a) the seat angles were changed from 45* to 50* (or greater?) w/ appropriate bowl mods for the difference in seat angle,
b) the before & after flow test showed losses in flow across some part (or all?) of the lift range consistent w/ the cam used,
c) yet before & after dyno tests verified the seat angle change alone resulted in more power?
Thanks - Brad

Yes, well the angle was changed from 50* back to 45* and intake valve size from 2.05" to 2.08".
The only change was intake valve diameter and seat angle. Ex stayed the same.
The cfm went up significantly. I don't have the flowz in front of me now but there was an increase in cfm at every lift.
I think the heads were flowing 290ish cfm with the 50* and 2.05 valve and they were over 300 with the 45* and larger valve. Nice cfm gain at every lift.
Back on the dyno they went backwards on power/score.

It's as back to back as I've done, but I have seen same cube/cam/comp type engines with/without steep seats with flow differences on the same dyno to certainly believe there is power potential in steeper seats on what I work on.

There will be several who will say "you just didn't get the cam right for the increase in flow" and that will be from ones who have done no testing at all, and even some who never even build any engines at all and just spread info from forum to forum or have been to a seminar or read a book that says so, so it has to be fact that you can't have less flow but more power.

From what I've seen, heads that run good just run good. They don't need a special cam to match the flowZ. You just put a cam in it and they run good. Some heads you can't make run good with any cam. If you do something to a set of heads that hurts the power over the full rpm range you pulled it , your just not gonna get it back with a cam much less a cam that will get it all back plus some.
There's more to it than what we see on a flow bench.

Randy

For discussion only....

In the example highlighted. Did you consider that the increased flow that resulted in the change to a larger valve and 45* seat also introduced turbulence somewhere upstream in the port that occurred @ the higher depressions seen in a running engine that may not have been evident on the bench @ 28"....?

[PRH]

I look at that example of where the bigger valve and 45* seat made less power in that example more or less along the lines of......it makes the cam “seem” bigger to the motor, particularly during the overlap triangle(where the C/D numbers were probably lower to boot)........ and it just wasn’t something that particular combo could benefit from.

It’s like when you increase the rocker ratio and the power goes down....... even when the heads are still showing improved flow at the higher lifts.
The increased opening rate and larger overlap triangle do more harm, than the added peak lift does good.
In a similar manor as the shallower seat angles, it makes the cam “seem” bigger....... which doesn’t always make more power.

[digger]

to play the devils advocate whats to say the valve angle had anything to do with the result at all....

[ClassAct]

to play the devils advocate whats to say the valve angle had anything to do with the result at all....

Because it's all about the SHAPE.

[CGT]

Well just my input from someone that was present for this:

You have two shortblocks prepared for EMC, roughly 40 cubic inches apart. Two set of heads from two different manufactures ported using different "ideas", two different manifolds ported by two different persons, 3 cams run through both at all positions, all this shit run through both engines. Score wise, once narrowed down to the smaller inch motor, the results of those two manifolds, 3 cams, 3 pans etc etc....remain in a very , very tight score range, Heads with a little bigger valve, 45° seat flowing more makes noticeable change to score for the bad.


Then knowing score and points have been hard to come by.....knowing the bigger valve higher flowing setup hurt it by a good amount? ...Do you go down that path, hopefully finding valve timing, shaping etc that it is capable of catching up to the deficit it started with then exceeding it? Or do you continue to refine what has already dynoed better everywhere? Is it a scientific test? no. But you can take what you want from it. Im not soliciting . Chop it apart however you feel.

[GARY C]

Some think throat size is critical and others think it doesn't matter... If it does then what should it be for this test and was it?
Some think chamber shape matters and others don't... If it does then what should be addressed here?
Conflicting info posted in regards to valve size and cams tested doesn't help... Should it be how many cams were tested or what cams were tested?
How does port shape differ from one to another if any?

Is any test considered valid or should it have a repeatable parameter like is done in science?

[Rick360]

Some think throat size is critical and others think it doesn't matter... If it does then what should it be for this test and was it?
Some think chamber shape matters and others don't... If it does then what should be addressed here?
Conflicting info posted in regards to valve size and cams tested doesn't help... Should it be how many cams were tested or what cams were tested?
How does port shape differ from one to another if any?

Is any test considered valid or should it have a repeatable parameter like is done in science?

None of our tests are scientific. Way too many parameters to isolate. Some single changes might never show a gain without also making a complimentary change. That branches out into more tests than a person has time for in their lifetime really quick. We don't have any control of inlet air conditions and only limited control of engine temps. We have to rely on correction factors to compare. You have to do the best with what you have to work with. Understanding the inaccuracies is part of forming an opinion of what is "better" when doing dyno testing. Make informed opinions about better or worse and incorporate those into your engines and they should improve.

There is no "perfect testing" in engine building. The final results is the only thing that matters.

Gary, it's obvious that our testing isn't up to your standards. You should do your own tests so you can do it right. Let us know when you get that done.

Rick

[RevTheory]

I can imagine trying to do a very specific seat angle vs valve timing test being problematic when under an EMC time crunch, especially when the dyno isn't yours to tie up forever.

[ClassAct]

Some think throat size is critical and others think it doesn't matter... If it does then what should it be for this test and was it?
Some think chamber shape matters and others don't... If it does then what should be addressed here?
Conflicting info posted in regards to valve size and cams tested doesn't help... Should it be how many cams were tested or what cams were tested?
How does port shape differ from one to another if any?

Is any test considered valid or should it have a repeatable parameter like is done in science?

None of our tests are scientific. Way too many parameters to isolate. Some single changes might never show a gain without also making a complimentary change. That branches out into more tests than a person has time for in their lifetime really quick. We don't have any control of inlet air conditions and only limited control of engine temps. We have to rely on correction factors to compare. You have to do the best with what you have to work with. Understanding the inaccuracies is part of forming an opinion of what is "better" when doing dyno testing. Make informed opinions about better or worse and incorporate those into your engines and they should improve.

There is no "perfect testing" in engine building. The final results is the only thing that matters.

Gary, it's obvious that our testing isn't up to your standards. You should do your own tests so you can do it right. Let us know when you get that done.

Rick

This^^^^^^^^^ It's a culmination of continuing development of flowbench/dyno/track time that will show trends. It's actually pretty easy to see trends develop over time when you are paying attention. Testing is testing. Time slips and lap times are the results that matter.

[BradH]

to play the devils advocate whats to say the valve angle had anything to do with the result at all....

Because it's all about the SHAPE.

Is it going off on too much of a tangent to segway into how chamber shape influences the "best" valve seat configuration?

[GARY C]

Some think throat size is critical and others think it doesn't matter... If it does then what should it be for this test and was it?
Some think chamber shape matters and others don't... If it does then what should be addressed here?
Conflicting info posted in regards to valve size and cams tested doesn't help... Should it be how many cams were tested or what cams were tested?
How does port shape differ from one to another if any?

Is any test considered valid or should it have a repeatable parameter like is done in science?

None of our tests are scientific. Way too many parameters to isolate. Some single changes might never show a gain without also making a complimentary change. That branches out into more tests than a person has time for in their lifetime really quick. We don't have any control of inlet air conditions and only limited control of engine temps. We have to rely on correction factors to compare. You have to do the best with what you have to work with. Understanding the inaccuracies is part of forming an opinion of what is "better" when doing dyno testing. Make informed opinions about better or worse and incorporate those into your engines and they should improve.

There is no "perfect testing" in engine building. The final results is the only thing that matters.

Gary, it's obvious that our testing isn't up to your standards. You should do your own tests so you can do it right. Let us know when you get that done.

Rick

I am not knocking your testing I am asking what effects what, if any one of these things has an effect on the other then it seems you would have to have at least 2 sets of heads done specifically for each and probably 3 cams per set, but what cams.

It seems engine builders have differing opinions as to valve to bore ratio and how important throat size is or isn't.

What rpm parameters would it need to be at?

Way to much time and money to be chasing a few hp and would probably just introduce more what if's.

So far I have found I can improve every part of the lift curve except for the one I am targeting so I will be happy just to figure that out but without before and after testing I may be chasing something that doesn't even matter.