50 degree valve seats in modern hot street builds: is it finally time?

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Frankshaft
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Re: 50 degree valve seats in modern hot street builds: is it finally time?

Post by Frankshaft » Fri Jun 15, 2018 12:33 pm

JoePorting wrote:
Fri Jun 15, 2018 12:24 pm
I've found that as air speed increases in a port, the air just doesn't want to turn. It just wants to go straight. So I believe that 5 degree steeper angle on the valve head allows the air to turn 5 degrees less around the valve which is where the flow increase comes from.
I called it mechanically bending of the air early on in this thread. And your right, that is one of the reasons. It creates less turbulence as more and faster air moves thru that area. Visualize a 30 -45-60 seat blown out around the top cut in chamber to " unshroud" the valves. Then visualize the same area with a 40-45 top, 50 seat, 65 and a 75, with a more gradual area change around the top cut in chamber. What would you imagine the air would be doing? Or not doing. Back to the simple logic and common Sense.

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Re: 50 degree valve seats in modern hot street builds: is it finally time?

Post by randy331 » Sat Jun 16, 2018 10:25 am

PRH wrote:
Mon Jun 11, 2018 5:36 pm
Would one expect similar results if the 50* seat resulted in a reduction of flow at all lifts,

I've seen less flow with 50s beat more flow with 45s,

But,....It's probably best to not go in the dyno room expecting anything . :D

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Re: 50 degree valve seats in modern hot street builds: is it finally time?

Post by Headguy » Sat Jun 16, 2018 11:01 am

randy331 wrote:
Sat Jun 16, 2018 10:25 am
PRH wrote:
Mon Jun 11, 2018 5:36 pm
Would one expect similar results if the 50* seat resulted in a reduction of flow at all lifts,

I've seen less flow with 50s beat more flow with 45s,

But,....It's probably best to not go in the dyno room expecting anything . :D

Randy
I've seen picking up flow down low to up top on 50s with simply the right back cut.

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Re: 50 degree valve seats in modern hot street builds: is it finally time?

Post by Walter R. Malik » Sat Jun 16, 2018 3:42 pm

randy331 wrote:
Sat Jun 16, 2018 10:25 am

But,....It's probably best to not go in the dyno room expecting anything . :D

Randy
You bet ...
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Re: 50 degree valve seats in modern hot street builds: is it finally time?

Post by NewbVetteGuy » Tue Jun 19, 2018 12:40 pm

GARY C wrote:
Wed Jun 13, 2018 7:17 pm
Frankshaft wrote:
Wed Jun 13, 2018 4:26 pm
GARY C wrote:
Wed Jun 13, 2018 3:16 pm

If it's the same one I am thinking of and I am not mistaken It got finished, dynoed and put in a Corvette!
If you say so. 👍
Talked to DV in regards to this.

The mag went under before the final part was published, it was dynoed by Jerry Goodale (spelling) at 710 hp 618 ft lbs, it was a 441 fuel injected engine built on a stock block that was later replaced by a Dart block due to cracks in the main webs around 3000 miles. It was installed in an 86 Corvette with a 5 speed trans, it ran 139 mph on street tires on it's one pass at the newly opened Speed Max (Z Max?), ET was not that great due to traction and not sure what trans gear was used at finish line... Several years have passed.

I do know there was an article about high horse street corvettes that used a photo of the under side of the car in reference to the lack of room for ex on vettes and it did have this system on it, or someone duplicated it.
Image
I've been enamored with the idea of a wave termination box since I read DV's Max Perf SBCs book; I haven't actually seen any such products for sale. Are these "vapor ware" or do they actually exist as a for-sale product some where?


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Re: 50 degree valve seats in modern hot street builds: is it finally time?

Post by GARY C » Tue Jun 19, 2018 1:47 pm

NewbVetteGuy wrote:
Tue Jun 19, 2018 12:40 pm
GARY C wrote:
Wed Jun 13, 2018 7:17 pm
Frankshaft wrote:
Wed Jun 13, 2018 4:26 pm


If you say so. 👍
Talked to DV in regards to this.

The mag went under before the final part was published, it was dynoed by Jerry Goodale (spelling) at 710 hp 618 ft lbs, it was a 441 fuel injected engine built on a stock block that was later replaced by a Dart block due to cracks in the main webs around 3000 miles. It was installed in an 86 Corvette with a 5 speed trans, it ran 139 mph on street tires on it's one pass at the newly opened Speed Max (Z Max?), ET was not that great due to traction and not sure what trans gear was used at finish line... Several years have passed.

I do know there was an article about high horse street corvettes that used a photo of the under side of the car in reference to the lack of room for ex on vettes and it did have this system on it, or someone duplicated it.
Image
I've been enamored with the idea of a wave termination box since I read DV's Max Perf SBCs book; I haven't actually seen any such products for sale. Are these "vapor ware" or do they actually exist as a for-sale product some where?


Adam
All the ones I have seen are home made, most cars have little room for them.

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Re: 50 degree valve seats in modern hot street builds: is it finally time?

Post by MadBill » Tue Jun 19, 2018 4:21 pm

Not universally loved, but some Flowmaster mufflers and others of similar design act as such boxes if the inlet pipe is pushed a couple of inches into the chamber. The few baffles of say a 40 Series provide sidewall support to prevent "oil-canning" fatigue failures.

I once had a chamber fabricated for a BBC Dually by closing in a pair of close-spaced 3" exhaust pipes to form an hourglass-shaped volume where they ran parallel for about 4' (with angled end fillers) and cutting front and rear openings into it. The butt dyno really couldn't call it, but I put a cable-operated damper valve in the middle and open/closed had quite an effect on the sound.
Felix, qui potuit rerum cognscere causas.

Happy is he who can discover the cause of things.


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Re: 50 degree valve seats in modern hot street builds: is it finally time?

Post by GARY C » Tue Jun 19, 2018 8:00 pm

I did a semi wave thingy, 3" X pipe dumped into 4" pipe tapered down to a 3" bullet for my 79 Trans Am, mostly because I had the parts and I like the X pipe sound.
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Re: 50 degree valve seats in modern hot street builds: is it finally time?

Post by steve cowan » Wed Jun 20, 2018 3:57 am

gary,
how loud was that setup ??
steve c

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Re: 50 degree valve seats in modern hot street builds: is it finally time?

Post by GARY C » Wed Jun 20, 2018 12:41 pm

steve cowan wrote:
Wed Jun 20, 2018 3:57 am
gary,
how loud was that setup ??
I pmed you, I can't post the idle video on here, it wont allow.

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Re: 50 degree valve seats in modern hot street builds: is it finally time?

Post by NewbVetteGuy » Tue Jun 26, 2018 1:26 pm

GARY C wrote:
Tue Jun 19, 2018 8:00 pm
I did a semi wave thingy, 3" X pipe dumped into 4" pipe tapered down to a 3" bullet for my 79 Trans Am, mostly because I had the parts and I like the X pipe sound.
Thanks Gary, great to see a real one. QQ: I thought the guideline was that the air volume in the wave termination box should be roughly equal to the CID of the engine; roughly where do you think the one in the picture fell? Roughly there or far less volume?


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Re: 50 degree valve seats in modern hot street builds: is it finally time?

Post by NewbVetteGuy » Tue Jun 26, 2018 1:55 pm

Rick360 wrote:
Tue Jun 12, 2018 1:49 pm
NewbVetteGuy wrote:
Tue Jun 12, 2018 1:15 pm
Rick360 wrote:
Mon Jun 11, 2018 9:52 pm
Here's a link to an old Speedtalk thread from 2005 that might be useful for some. This post/thread was my initial inspiration as to a new reason other than flow "why" steeper seats might be better, although I already had a set of heads with 50º seats by then. This certainly got me thinking along new lines.

http://www.speedtalk.com/forum/viewtopic.php?f=1&t=1257

Rick
Rick, I really appreciate you posting a link over to that thread, making the XLS, and making and posting the pictures.

I just used the XLS to look at the minimum window area of a 2.02" valve with 50/43/35 valve angles vs. 45/35/30 valve angles at 0.100" increments up to 0.700" and then also added one more data point at 1.000". I did not see what I expected and I think I'm more confused, but possibly on the cusp of understanding something new...

2.02" Valve "typical" 50 vs 45 degree valve job min window area at various lifts:
Valve Lift 45 50
0.100" 0.459 0.413
0.200" 0.975 0.855
0.300" 1.504 1.417
0.400" 2.075 1.984
0.500" 2.661 2.568
0.600" 3.254 3.16
0.700" 3.85 3.756
1.000" 5.649 5.555


I fully expected to see the 50 degree seat start out with less window area at lower lifts and then at some point transition to having a larger window area (much like we see the CFM flow #'s cross over in the HotRod article), but we don't see that actually ever happen. The 50 degree angle starts out with less window area and stays that way at all lifts... Did I do this right?

Is this correct that the 50 degree angle valve will have less actual curtain area at all lifts but still somehow flows more? (simply because the angle of the valve and seat let the air flow FASTER?) More air flow with the same area == more velocity, but this seems to be more airflow with less area -so potentially significantly higher velocities through the valve curtain area??? (At least at the lifts where the valve curtain area is still the bottleneck /choke point.)

On a related note, unless I totally screwed up something above (WAY more than possible): When calculating at which valve lift point the choke moves from the valve curtain area to the intake port's choke / minCSA, should we actually be using this more complicated Window Area Calculation? (If so it seems like it will take more lift with a 50 degree seat to reach the point when the throat becomes the choke, right?)



Adam
Yes, I think you've got a pretty good understanding. One other thing about the area is that the steeper seats starts gaining back some area deficit to the 45 at about .100"-.150" lift depending on angles and widths. The rate of change in area per lift or "slope" of the area vs lift gets much better around that lift. Slower opening area at real low lifts where not much can happen yet then faster area opening at about the lift when the valve can really start to move out of the way. It acts like a faster lobe. Or thats how I see it.

Rick
Ok, I've done some more homework and have some more questions now.

Rick, I used your XLS to generate the "minimum window area" @ 0.100" increments with a typical 45 degree 3 valve angle and a 50 degree valve angle, I compared it to the standard "Diameter*Pi*Lift" calc and the "Diameter*0.98*Pi*Lift" calculation, for giggles, I used the Wallace Racing curtain area calculation, too and it's yet another, different #. The traditional formulas obviously have a pretty big difference with the new XLS.

I wanted to calculate the point at which my Profiler 195cc heads with a 2.15" min CSA would see the actual min CSA / choke point move from the valve to intake tract, the simple Diameter*Pi*Lift calculation estimates @ 0.339", but the new formula says you have to lift the valve 0.429" with a 45 degree valve and 0.431" with the 50 degree seat angle profile(and my 2.02" intake valves), assuming I did it right.

Question: When calculating Discharge Coefficients, shouldn't we be using the more accurate curtain area calculations as the basis?


Next, I want to use your calculator and the FLOW #'s from the HotRod 45 degree vs. 50 degree article to calculate the discharge coefficient at each 0.100" of lift between the 45 and 50 degree seats; I should just use the formula: window area * 146 = theoretical maximum flow for that area, but use the calculator's, more accurate valve curtain area calculation, right?


Adam

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Re: 50 degree valve seats in modern hot street builds: is it finally time?

Post by GARY C » Tue Jun 26, 2018 5:04 pm

NewbVetteGuy wrote:
Tue Jun 26, 2018 1:26 pm
GARY C wrote:
Tue Jun 19, 2018 8:00 pm
I did a semi wave thingy, 3" X pipe dumped into 4" pipe tapered down to a 3" bullet for my 79 Trans Am, mostly because I had the parts and I like the X pipe sound.
Thanks Gary, great to see a real one. QQ: I thought the guideline was that the air volume in the wave termination box should be roughly equal to the CID of the engine; roughly where do you think the one in the picture fell? Roughly there or far less volume?


Adam
Yes they were undersized, they were 2' long. 5 inch pipe would have been ideal but wouldn't fit.

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Re: 50 degree valve seats in modern hot street builds: is it finally time?

Post by Rick360 » Tue Jun 26, 2018 8:54 pm

NewbVetteGuy wrote:
Tue Jun 26, 2018 1:55 pm
Ok, I've done some more homework and have some more questions now.

Rick, I used your XLS to generate the "minimum window area" @ 0.100" increments with a typical 45 degree 3 valve angle and a 50 degree valve angle, I compared it to the standard "Diameter*Pi*Lift" calc and the "Diameter*0.98*Pi*Lift" calculation, for giggles, I used the Wallace Racing curtain area calculation, too and it's yet another, different #. The traditional formulas obviously have a pretty big difference with the new XLS.

I wanted to calculate the point at which my Profiler 195cc heads with a 2.15" min CSA would see the actual min CSA / choke point move from the valve to intake tract, the simple Diameter*Pi*Lift calculation estimates @ 0.339", but the new formula says you have to lift the valve 0.429" with a 45 degree valve and 0.431" with the 50 degree seat angle profile(and my 2.02" intake valves), assuming I did it right.

Question: When calculating Discharge Coefficients, shouldn't we be using the more accurate curtain area calculations as the basis?


Next, I want to use your calculator and the FLOW #'s from the HotRod 45 degree vs. 50 degree article to calculate the discharge coefficient at each 0.100" of lift between the 45 and 50 degree seats; I should just use the formula: window area * 146 = theoretical maximum flow for that area, but use the calculator's, more accurate valve curtain area calculation, right?


Adam
Without the valve back-cut angle and width, and in some cases the valve back angle, you can't calculate the real curtain area right. The Wallace calculator doesn't ask for those inputs so it is doing a simpler method that is less accurate. Looking at curtain area at low lifts with different back-cut widths and angles will tell you a lot about why the low lift flow improves with valve back-cuts.

As far as discharge coefficients, I prefer to use cfm/sqin (cfm of airflow per square inch of flow area). Making them into coefficients just complicates things because different people use different "max" flow for the DC calc, and even 146cfm/sqin is not a flow limit for airflow with 28" dp across a port. But to answer your question, yes using the most accurate area calculation will obviously give you the best information for comparisons. The curtain area is not the most important area when the valve is open fairly high in the lift curve. The valve throat cfm/sqin is a more important number i like to look at when the valve is open a lot.

Using real curtain area cfm/sqin at all lifts you flow would be useful and certainly better than the simple curtain method. Throat cfm/sqin should also be looked at and for all out power is probably more important. (make sure to subtract the valve stem area from your area)

Rick

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