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

[GARY C]

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.

Yes that seems to be the issue with this subject, my example creates 4 tests with one valve angle that would require 2 sets of heads and that's only comparing 2 different 45 degree cutters. You could probably do a years worth of testing on just 45* cutters and valve head shapes alone and get a variety of results.

[paulzig]

Your familiar with pseudo, that's the one I've had in the back of my mind to do a valve job test on some day. It's still the GM valve job and 2" valve, so options are open on what can be done.

Randy

Trying it on pseudo 383 sounds like a good idea just the 50 cut on IN and EX is enough to see a trend. Dont have to go spending 1000s on magic camz or flowing heads the cam is on 108LSA people should be happy with that.

It already made really good power with the stock GM valve job.

[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.

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

Although I used an outlier for an example, Warp got my main point. The insinuation was that.. people are cheap and often misinformed.. and don't always use good combinations of parts.

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.

Seems doubtful that a crappy as cast SSR on a 23° head which already has turbulence issues would be helped out in every way shape or form.. but maybe the bigger steeper throat cut helps reshape the SSR and push the apex closer to the inlet? I do know for fact that running a steep 84-88° bowl hog has that same affect but is tougher to do with oversized valves eating up more beach front real estate. Implying that just because you're experience has pointed towards a linear response to a steeper VJ working on everything is misleading and misrepresenting the experiences of thousands of others who've worked with many castings for which you may have never tested the results of a steeper seat profile. Not really saying you're wrong.. just that blanket statements usually never cover the whole picture.

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

Probably should read it so I have reference to what you're even talking about. lol I tend to go with what I KNOW WORKS based on personal testing and experience and then does what I expect it to 100%. If my experiences with 50° stuff was even remotely in the same ballpark then I'd probably never ask questions and just go with what I know about that too. Up until now I've never put a steeper valvejob on anything short of full race stuff. I bought different SBF castings specifically for a 50° seat profile.. was even thinking on going towards a 52°.. so fear is not the main holdup.. ending up with something only marginally better because some of the supporting angles or valve profile wasn't up to the task is the bigger concern. I can come up with a few really great angle combinations that look awesome on paper.. but if they don't actually fit the casting without adding other compromises into the mix.. they're never going to amount to reality.

I think some of the disconnect here between various results and testings outcomes between various porters and guys spec'ing their own VJ's, is related to the number of angles some guys may be using. I myself have always favored higher count and narrower multi-cuts with very steep cut bowl angles hand blended which generally eats up more bowl material and leaves a larger throat % than some others only using traditionally sized and width 3 or 4 or even 5 angles. I've been upwards of 7 cuts and used the lower 4 cuts only as a sizing template for hand blending right up to the bottom cut. I think my Kaase P38's came with 6 cuts?.. and the bowls were already huge as cast. Point is that I understand the merits of the steeper seats towards a more idealized and developed flow cone around the valve and seat area but there are also some guys grinding out there approaching the larger throat sizes of say.. a 4 angle 50° setup even though they are built around the shallower 45° valve/seat angles. There are just soooo many possibilities for angle transition variations and cut widths that there is a crossover effect in where some valvejobs can mimic others in certain aspects of operational performance. And what works well on 1 style casting may not be the most idealized for another when you consider the available area and what can be made to fit into it.

The test I would like to see is a "happy medium" street/strip style cam that is known and tested to produce solid and repeatable results with a 45° VJ. But do the testing on 2 same part # castings with each having an idealized valve/seat profile for that particular castings material availability and port architecture. Start removing too much material to do a really nice 45° VJ and you may not end up having material left in the exact places required to do a really nice 50° VJ on that same casting and same sized valve. You could always add a little valve size but then the test would be flawed for any type of real comparison. You'll be forced to cut what fits in the remaining material availability and it will limit shaping options. Then move the cams around for both those head tests and see what the results amount to in the 2,000 - 7,000 range. Starting the pull out at 3,000 rpm will only serve to tailor the testing towards the steeper angle head combo. The wider the rpm window in testing.. , even if less than ideal for that camshaft, the more visible the trends will become.

[PRH]

In the 35/45/50 test, the 50 seat had the best high lift flow.

Would one expect similar results if the 50* seat resulted in a reduction of flow at all lifts, like in the example I posted near the beginning of this thread?

How I would do the test is, use a pretty common basic bracket type head(like a Dart 200 or 215), do a nice 45* seat and mild blend, and then use another set of the same castings with a 50* seat based on info from the pro50 group, along with a similar blend.
Try both sets on a decent short block with a bread and butter bracket cam and see what happens.

[groberts101]

How I would do the test is, use a pretty common basic bracket type head(like a Dart 200 or 215), do a nice 45* seat and mild blend, and then use another set of the same castings with a 50* seat based on info from the pro50 group, along with a similar blend.
Try both sets on a decent short block with a bread and butter bracket cam and see what happens.

Awesome idea!.. wish I would've thought of that one. JK.. well.. mostly.

[Warp Speed]

...

[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!

Although I used an outlier for an example, Warp got my main point. The insinuation was that.. people are cheap and often misinformed.. and don't always use good combinations of parts.

That's part of the problem though. Everyone keeps throwing "outliers" to try and prove some point or something. Doubt everything initially, but after a while, with many proponents, maybe you should start considering the possibilities, instead of purely waging rebuttal?
Or not............
People that aren't using a good combination of parts, should probably get the basics figured out before trying it. The rest should be giving it more thought. The ones who have tried with mixed results, might need to look at the surrounding angles and approach.
But we are almost to the point of waisting bandwidth here! Lol

[statsystems]

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

Although I used an outlier for an example, Warp got my main point. The insinuation was that.. people are cheap and often misinformed.. and don't always use good combinations of parts.

That's part of the problem though. Everyone keeps throwing "outliers" to try and prove some point or something. Doubt everything initially, but after a while, with many proponents, maybe you should start considering the possibilities, instead of purely waging rebuttal?
Or not............
People that aren't using a good combination of parts, should probably get the basics figured out before trying it. The rest should be giving it more thought. The ones who have tried with mixed results, might need to look at the surrounding angles and approach.
But we are almost to the point of waisting bandwidth here! Lol

Haaaaaaaaaaayup. Lots of mental masturbation, what if'ing, posturing and looking for a reason to not do something.

If I was that worried I'd have never done my first steeper than 45* seat.

Like I said...when I first learned of it I got on the phone, read all I could and started testing. 50* seats on a street performance head should be moving towards the norm.

[randy331]

50* seats on a street performance head should be moving towards the norm.

WHAT ?? BUt,... I just ordered a 30* cutter.

Guess i need to re read this thread.

Randy

[groberts101]

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

Although I used an outlier for an example, Warp got my main point. The insinuation was that.. people are cheap and often misinformed.. and don't always use good combinations of parts.

That's part of the problem though. Everyone keeps throwing "outliers" to try and prove some point or something. Doubt everything initially, but after a while, with many proponents, maybe you should start considering the possibilities, instead of purely waging rebuttal?
Or not............
People that aren't using a good combination of parts, should probably get the basics figured out before trying it. The rest should be giving it more thought. The ones who have tried with mixed results, might need to look at the surrounding angles and approach.
But we are almost to the point of waisting bandwidth here! Lol

People here and everywhere are using less than optimum parts. I have no agenda and simply threw reality into a scenario where there are no specific angle recipes(even pro's can't completely agree much of the time) or unified results that have been proven across the board no matter the application. If results really were unified and easy to implement without fail.. many more would be implemented and proof would be undeniable. That's nowhere near the case though with many world famous pro's still using 45's on many applications drspite that old cat being let out of the bag long long ago. If that doesn't fit your specific criteria and makes me a critic to your cause here?.. so be it. In that same respect, I also don't agree that every 45 seat profile works across the board on every application either.. but that doesn't make me a 45 degree seat critic either.

To do well at anything you need to think objectively as well as subjectively while making preasessed compromises towards a desired result. Seems obvious but I'll state it anyways.. not everyone thinks like that or chooses to make the same exact compromises. So end results will always vary.

[groberts101]

50* seats on a street performance head should be moving towards the norm.

WHAT ?? BUt,... I just ordered a 30* cutter.

Guess i need to re read this thread.

Randy

You guys are so wishy washy. "I do them on EVERYTHING. for the last 20 years". No wait.. "I'm not saying they always work for every application". Errr.. "IF doing additional port work". But "if using less than 10 degree angle transitions".... "gotta have a 45 topcut"...

Read back some of what all the pushers have written on several threads lately. Not to mention the dozens of previous ones here and elsewhere. And many of those come from cylinder head designers and world renowned engine builders too. You guys around here can't even find common ground other than saying.. "you guys need to be over here on this side if you want better results!" You should just agree to agree and keep posting exceptional build results. Lead by example and people will ask questions and then quickly copycat the hell out of the techniques used to get those outstanding results. Just an idea.

[Rick360]

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

[Rick360]

Here is a drawing I posted back then that is probably a dead link now so I'll put it here as an attachment. Shows where the narrowest point is at different valve lifts. If you can picture what a steeper seat does to the gaps at the different lifts.

ValveSeatDwg.jpg

Rick

[statsystems]

50* seats on a street performance head should be moving towards the norm.

WHAT ?? BUt,... I just ordered a 30* cutter.

Guess i need to re read this thread.

Randy

You guys are so wishy washy. "I do them on EVERYTHING. for the last 20 years". No wait.. "I'm not saying they always work for every application". Errr.. "IF doing additional port work". But "if using less than 10 degree angle transitions".... "gotta have a 45 topcut"...

Read back some of what all the pushers have written on several threads lately. Not to mention the dozens of previous ones here and elsewhere. And many of those come from cylinder head designers and world renowned engine builders too. You guys around here can't even find common ground other than saying.. "you guys need to be over here on this side if you want better results!" You should just agree to agree and keep posting exceptional build results. Lead by example and people will ask questions and then quickly copycat the hell out of the techniques used to get those outstanding results. Just an idea.

No one is pushing anything. What you want is a single answer and there isn't one. There are several 50* seat cutters. There is no one fits all.

That is exactly what I said way back in this thread. You want someone to hand hold you through the whole process. That's rediculous.

Again, remember what Darin Morgan said...he still uses 1.88 exhaust valves because that's what people wanted. I suspect the same thing happens with valve jobs.

Stay with the 45 on everything. You'll be happier.

[statsystems]

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

Just read through that thread. Pretty interesting. It's a 13 year old thread.