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

[RevTheory]

I don't think it needs to be that complicated to see a trend. As "cam based on flowz" as I am, I think it can still be a viable test with a single cam + ICL sweep. However, I can't imagine a world where Randy is allowed to do the 45* seats and the GM-cut seats vs custom 50s isn't a fair test either.

Just my opinion though and we know what those are worth.

[groberts101]

Seems like a waste of time and yet another thing to argue about. lol

IMO, the data is already out there and results most definitely show the trends for more serious race motors. While another hot street build might show trends toward usage of 50's for street strip duties.. it still will not tell the average person reading those specific results how to fit that data to another entirely different combination of parts even if having similar rpm ranges. IOW, what works for a revised port design gmpp casting will do nothing to show how a guys camel hump heads and dual plane intake will respond.

[Warp Speed]

Seems like a waste of time and yet another thing to argue about. lol

IMO, the data is already out there and results most definitely show the trends for more serious race motors. While another hot street build might show trends toward usage of 50's for street strip duties.. it still will not tell the average person reading those specific results how to fit that data to another entirely different combination of parts even if having similar rpm ranges. IOW, what works for a revised port design gmpp casting will do nothing to show how a guys camel hump heads and dual plane intake will respond.

I get your point I guess, but who still uses camel hump heads, except maybe for a restoration?!?
Serious question!

[CGT]

Seems like a waste of time and yet another thing to argue about. lol

IMO, the data is already out there and results most definitely show the trends for more serious race motors. While another hot street build might show trends toward usage of 50's for street strip duties.. it still will not tell the average person reading those specific results how to fit that data to another entirely different combination of parts even if having similar rpm ranges. IOW, what works for a revised port design gmpp casting will do nothing to show how a guys camel hump heads and dual plane intake will respond.

I disagree. The effects of the steeper seat, smaller window or the shallower larger window on the power curve will be very transferrable to other platforms. Its not going to spell it out for your given project exactly to the tee like a recipe. But a person can use the data as they see fit.

[randy331]

Seems like a waste of time and yet another thing to argue about. lol

IMO, the data is already out there and results most definitely show the trends for more serious race motors. While another hot street build might show trends toward usage of 50's for street strip duties.. it still will not tell the average person reading those specific results how to fit that data to another entirely different combination of parts even if having similar rpm ranges. IOW, what works for a revised port design gmpp casting will do nothing to show how a guys camel hump heads and dual plane intake will respond.

I disagree. There's info in the article Daryl did for about anyone. It has low lift and small valve, how many would have thought a seat set up that had less window at all lifts would add power at any rpm with such a small cam ?

Your trying too hard to convince yourself not to try a 50 on something. If it don't work for you, go back.

I guess that means your out on donating a little to help fund the test ?

edit, see Chad's post above.
Randy

[CGT]

Seems like a waste of time and yet another thing to argue about. lol

IMO, the data is already out there and results most definitely show the trends for more serious race motors. While another hot street build might show trends toward usage of 50's for street strip duties.. it still will not tell the average person reading those specific results how to fit that data to another entirely different combination of parts even if having similar rpm ranges. IOW, what works for a revised port design gmpp casting will do nothing to show how a guys camel hump heads and dual plane intake will respond.

I think your internal valve seat angle struggle should be over. Run the 45

[RevTheory]

Although I've been wrongly pigeonholed, my curiosity is way up and I'm looking for all the reasons in the world to us steeper seats. It just needs to make sense for the way I like my torque curves and that's strictly everyone's personal opinion.

[JoePorting]

I went back to the Hotrod Magazine test results to see if I can see something from the data. The flow bench results seemed to be consistent. The lower 35 degree valve angles did better in the low lift areas while the 50 degree angles did better in the high lift areas:

Flow......35.......45......50
.100......71….....63......62
.200.....138.....129.....126
.300.....182.....187.....183
.400.....218.....224.....226
.500.....229.....227.....235
.550.....229.....229.....234

[user-30563]

Why doesn't anyone mention how the valve job is blended? You can easily kill 10cfm down low with blending..

[JoePorting]

But the dyno results appear to be inconsistent with the 35 degree angle actually doing better in the 3500-3750 rpm range and then coming back and doing better in the 6250-6500 rpm range. The 45 degree angle appears to be doing the worse overall, but the 50 degree angle appears to do better overall with it winning nine of the rpm ranges while the 35 degree angle wins four of the rpm ranges:

HP...…..35...….45......50
3500....235....215....219
3750....256....253....253
4000....276....278....284
4250....292....297....312
4500....311....312....332
4750....328....330....346
5000....343....339....355
5250....353....346....365
5500....358....348....369
5750....358....347....367
6000....362....354....363
6250....363....354....358
6500....361....349....348

If we compare the 35 degree angle to the 45 degree angle, the 35 degree angle wins nine of the rpm ranges while the 45 degree angle only wins four of the rpm ranges.

So it appears there's a number of factors going on here with the net effect being the results.

One thing to mention that I would think would be a test failure is that the article says they went from a 45 degree test to the 35 degree test to then the 50 degree test. But if they did that, then the 35 degree test would not have been right because the lower angles would have been from the 45 degree angles. To do the test right they should have started with the 35, then gone to the 45, and finished up with the 50. That would have tested all the angles right. But the 45 to 50 degree test should have been done right.

[CGT]

But the dyno results appear to be inconsistent with the 35 degree angle actually doing better in the 3500-3750 rpm range and then coming back and doing better in the 6250-6500 rpm range. The 45 degree angle appears to be doing the worse overall, but the 50 degree angle appears to do better overall with it winning nine of the rpm ranges while the 35 degree angle wins four of the rpm ranges:

HP...…..35...….45......50
3500....235....215....219
3750....256....253....253
4000....276....278....284
4250....292....297....312
4500....311....312....332
4750....328....330....346
5000....343....339....355
5250....353....346....365
5500....358....348....369
5750....358....347....367
6000....362....354....363
6250....363....354....358
6500....361....349....348

I wouldn't put too much faith in the first rpm data point or two. Its easy to get some glitchyness at the beginning and sometimes the very end of a pull depending on several factors.

[JoePorting]

But the dyno results appear to be inconsistent with the 35 degree angle actually doing better in the 3500-3750 rpm range and then coming back and doing better in the 6250-6500 rpm range. The 45 degree angle appears to be doing the worse overall, but the 50 degree angle appears to do better overall with it winning nine of the rpm ranges while the 35 degree angle wins four of the rpm ranges:

HP...…..35...….45......50
3500....235....215....219
3750....256....253....253
4000....276....278....284
4250....292....297....312
4500....311....312....332
4750....328....330....346
5000....343....339....355
5250....353....346....365
5500....358....348....369
5750....358....347....367
6000....362....354....363
6250....363....354....358
6500....361....349....348

I wouldn't put too much faith in the first rpm data point or two. Its easy to get some glitchyness at the beginning and sometimes the very end of a pull depending on several factors.

But it's strange that the 50 degree seat falls on it's face in the high 6250-6500 range. I'd think that's when it would shine the best, but instead the 35 does better there. I guess the reversion quality of the 50 degree seat goes away after 6000 rpm's while the low lift flow cylinder filling capabilities of the 35 improve overall power.

[CGT]

But the dyno results appear to be inconsistent with the 35 degree angle actually doing better in the 3500-3750 rpm range and then coming back and doing better in the 6250-6500 rpm range. The 45 degree angle appears to be doing the worse overall, but the 50 degree angle appears to do better overall with it winning nine of the rpm ranges while the 35 degree angle wins four of the rpm ranges:

HP...…..35...….45......50
3500....235....215....219
3750....256....253....253
4000....276....278....284
4250....292....297....312
4500....311....312....332
4750....328....330....346
5000....343....339....355
5250....353....346....365
5500....358....348....369
5750....358....347....367
6000....362....354....363
6250....363....354....358
6500....361....349....348

I wouldn't put too much faith in the first rpm data point or two. Its easy to get some glitchyness at the beginning and sometimes the very end of a pull depending on several factors.

But it's strange that the 50 degree seat falls on it's face in the high 6250-6500 range. I'd think that's when it would shine the best, but instead the 35 does better there. I guess the reversion quality of the 50 degree seat goes away after 6000 rpm's while the low lift flow cylinder filling capabilities of the 35 improve overall power.

The 50 being better down low and making more peak power sooner is exactly what I would expect to happen. Definite VE increase there.

[GARY C]

I went back to the Hotrod Magazine test results to see if I can see something from the data. The flow bench results seemed to be consistent. The lower 35 degree valve angles did better in the low lift areas while the 50 degree angles did better in the high lift areas:

Flow......35.......45......50
.100......71….....63......62
.200.....138.....129.....126
.300.....182.....187.....183
.400.....218.....224.....226
.500.....229.....227.....235
.550.....229.....229.....234

The issue I see with quoting a valve angle and using a flow number to push a view point is that one valve angle done differently will flow and perform differently, you could do the blend, top cut and bowl different on the 35 and possibly make it out flow the other 2 or at least come close to the 50 up top.
Here is a 200 cc EQ Iron 50CC chamber 2.02 valve head I played with.
OTB port and 45 set
.050 .100 .200 .250 .300 .400 .500 .600 .700
34 70 133 163 190 232 257 273 277
OTB port with multi angle valve job 45 seat
33 66 130 162 186 223 248 264 266
Bowl blend, clean short turn same port with multi angle 45 seat
33 66 134 166 193 238 266 286 288

FYI the same bowl work and st clean did nothing to change the otb flow number until the valve job was redone and then it went to the higher flow number.

[Frankshaft]

That test can't be taken as the end all be all, and every conclusion about the subject made from it. I mentioned earlier, that it shows the trend. And how it works absolutely opposite of what most have been taught, happens. I mentioned earlier, the "Stock" 45 valve job, is likely not ideal, and definitely could be improved. I didn't like the 50 degree profile either. The engine simply needs more camshaft now, and it would carry up top and make more. There will be a convergence point where the low lift valve job will fall off hard, as the other Dynamics at play start to come into play more. Also, using the same 2 heads for the test kinda throws it off too. Depending on what order they did the valve jobs, could have a different affect on the out come.