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

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

Post by NewbVetteGuy » Fri Jun 01, 2018 6:47 pm

I'm a newb, it says it right in my forum name. But I can't help but see the results from a few of Randy & Rick's builds and EMC entries that are using 50-degree valve seats and seeing decent gains in average torque and power at very typical modern "street" valve lifts and RPMs and wonder: why not?!?

Most of these threads on this subject have been SUPER technical and I've tried to hang with them and absorb what I could but I'd love to see some lessons learned boiled down to some simpler and more salient points for any other Newbs/dummies like me.


My dumb newb conclusion is that it kinda looks like modern fast-ramp cams and supporting spring technology, and top-tier head designs mean that you can get a valve at higher lifts, for longer than you previously could and there ARE average power advantages that can be had EVEN at hot street valve lifts and RPMS...


Question: At what point do 50 degree valve angle's performance benefits start to make sense? I'm looking for an answer within the modern context of today's top-brand 23 degree SBC heads, & fast ramp -high lift street cams.

-I read somewhere that an old rule-of-thumb was that you don't see real gains on a 50 degree valve seat angle vs. a 45 degree valve seat angle until you get to an 0.25 lift to valve diameter L/D ratio (0.505" lift with a 2.02" valve diameter), but looking at a few real-lift examples, it seems that the benefits start FAR before that point (0.364" of valve lift with a 2.02" valve??)...

Example #1: http://www.hotrod.com/articles/1203phr- ... valve-job/ 1.94" diameter valve; Vortec head: Started showing airflow gains on the bench @ 0.350. That's gains starting at an L/D of 0.18. ->Does that mean that a typical 2.02" valve would start to see gains at that same L/D ratio? (0.364" and up?) On the dyno the engine saw the same or better torque across the whole curve from 3,500 - 6,500; an average gain of +12 ft lbs and a peak gain of 22 ft lbs @ the torque peak RPM. -Again this is with a super streetable, off-the-shelf Comp Cam (unknown #) with a max lift of 0.522 -VERY normal street stuff.

Example #2: The 2017 EM Traditional Muscle category winner from the Creason team. (Of course I'm using that example.) Ported Profiler heads, 2.02" /1.6" valve combo 238/244 @0.050 cam, 0.595" lift at the valve. (not sure on the seat-to-seat or advertised duration, but I'm betting it's pretty tight for the @ 0.050" #'s given the 1.8 / 1.85 rockers) -Yes it's an Engine Master's engine and yes the valve train is exotic but a 238/244 @ 0.050" diameter and 0.595" lift at the valve and the seat durations I bet are very reasonable for a modern, fast ramp roller cam. The hp peak @ 6,500. The whole thing (if it were on a roller cam with more reasonable 1.6 rockers) is very typical street stuff and I'm assuming it's benefiting similarly from the 50 degree seat angles or they wouldn't have gone with it in the first place. Randy talks up 50 degree seat angles in quite a few of his builds on here; most of them with bigger lifts and more RPM than this, though...


-It seems like the benefits of going with a 50 degree valve seat angle are very much applicable to modern street motor valve lifts and RPMs, no? Do the fast ramp speed cams and higher ratio rocker that help get the valve open quickly and into the "good air" (now even better air with the 50 degree seat angles) and to keep the valve in the good air for more degrees of duration, make up for the loss in low lift flow? (seems like it)


-Are there valve/seat / spring technologies that can help with longevity with a 50 degree valve seat angle? I'd think that a cam with a slower close ramp that could set the valve down nice and easy (isn't this the purpose of a "dual profile" cam-intake open agressively fast, but decelerate on the close ramp and avoid the "sewing machine" closes), and beehive or conical springs that are "just enough" pressure for the application could still go a good number of miles before you'd need to replace the valves.... -Yes / No? -Estimates on longevity?


Anyone have a before / after 45 degree / 50 degree dyno chart that goes a bit lower in RPMs? -I'm curious what the before and after torque looks like down at highway cruise RPM and a 50 degree seat would impact highway cruise MPG. A decrease in reversion during overlap from 50 degree valve angles should help MPG, right? (If torque is up and reversion is down then that should be an MPG @ cruise RPM benefit for 50 degree seat angles, too...)



Summary of my thoughts: The benefits of a 50 degree seat angle seem to be far more applicable to a modern street build than the old "only at high rpms and only beneficial over 0.550" valve lift" arguments; and if it's possible to still go 60,000 miles between top-end rebuilds with an appropriate cam and valve train, shouldn't more people go this direction?

More average torque, more peak RPM and still many, many YEARS between rebuilds for weekend-driven or summer-driven street cars sounds wonderful to me...



Adam
Last edited by NewbVetteGuy on Fri Jun 01, 2018 7:25 pm, edited 4 times in total.

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

Post by statsystems » Fri Jun 01, 2018 7:12 pm

Yes, the time for 50* seats is here. Was here years ago.

The problem is guys who live and die by flow bench numbers look at a 50* valve job say it won't work in a street car because low lift is down, and you only get it back until high lift.

I consider that an abuse of a flow bench.

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

Post by GARY C » Fri Jun 01, 2018 7:24 pm

You will get different theory's on this, Gary Theory, on the intake your reducing reversion while taking advantage of more aggressive lobe profiles or longer lobes with more area. On the ex you don't dump compression pressure on opening and your reducing reversion at overlap.
The guy that does my machine work uses 45 but he quit doing back cuts because he finds the with the parts available today they make more power then the older days when a back cut was the way to go.
He does some heads for a stock head class Mopar that makes better power with a 45 intake and a 50 or 55 exhaust.
Jon Kasse seems to relate it more to throat area then valve angle in this article. http://www.hotrod.com/articles/1203phr- ... valve-job/
Brothers Rick and Randy Ferbert, who recently competed in the 2011 AMSOIL Engine Masters Challenge with a Bow Tie Vortec-headed 383 small-block Chevy, mentioned during teardown (look for an upcoming feature article on the all-iron small-block) that they put a 50-degree valve job on their engine. That’s traditionally been reserved for high-lift, high-rpm race engines. What gives? A conversation with Pro Stock engine builder Jon Kaase seemed to indicate it might not be worth it. “We tried different valve jobs a few years ago, and really didn’t find much there so we just stick to the same one we always use [on the high lift engines].” Kaase mentioned he ran a 30-degree valve job on the potent Pontiac he entered in the Engine Masters Challenge a few years back, but was unsure whether that was a good or bad thing. “If the seat ID is the same when you got all done below the angles, I don’t know if it’s going to make a real big difference.” For the most part, Kaase recommended a common 45-degree valve job for “normal” lift engines. The fact that the Ferberts had such a steep angle on their small-block with only a .650-inch lift cam got us scratching our collective noggins and wondering how deep we could delve into the geometric world of valve jobs without an advanced engineering degree.
I have seen side by side flow numbers posted here of a 45 vs 50 and they were within a few #'s of each other so I guess it depends on your seat, top cut and blend at the bowl.
Last edited by GARY C on Fri Jun 01, 2018 7:29 pm, edited 1 time in total.
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Re: 50 degree valve seats in modern hot street builds: is it finally time?

Post by NewbVetteGuy » Fri Jun 01, 2018 7:29 pm

statsystems wrote:
Fri Jun 01, 2018 7:12 pm
Yes, the time for 50* seats is here. Was here years ago.
Even on street builds? -At what max lobe lift would you recommend someone should go with a 50* seat (where's the tipping point)?


What about the longevity concerns? Can they be addressed? How? -What's the super rough difference in mileage between rebuilds with 45 deg and 50 degree seats?


50* just on the intake or intake and exhaust?


Adam

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

Post by NewbVetteGuy » Fri Jun 01, 2018 7:55 pm

SBC 350, 10.2:1 Static CR
Profiler 195cc heads (as cast); 2.01"/1.6" valves (PAC beehive springs * 10 deg steel retainers recommended by Mike Jones)
Cam: Mike Jones HR70375 -aggressive HR but not his noisy, REALLY aggressive lobes 227/228 @0.050 272/280 @0.006" .375"/.360" lobe lift (0.600"/0.576" with my 1.6RR)


Any guess what kind of increase I'd see if at next rebuild I moved to 50 degree seats?
How would you go about estimating such a thing?

(Danger: Newb making up not only #'s but calculations based upon nothing): Just roughly estimate +10 CFM at 0.500" - 0.600" lift? 273 CFM -> 283 CFM or a 3.7% increase; then take current ft lbs between 3,500 and 6,000 and multiply by 1.037 to end up with magical space math new torque estimates?!?

All baiting of the calculation nerds aside, I REALLY like super torquey street builds (I went with the strange aftermarket TPI-style "FIRST Fuel Injection" intake, the Profiler heads, a short-ish duration, high-ish lift cam, tri-y headers based build for that reason) and the idea of another 10-15 ft lbs everywhere in the curve and a bit of anti-reversion for going with a 50 degree seat angle valve, if I can still get 50,000 miles between rebuilds, sounds like the kind of trade-off I'd be happy to make.

-I see huge conflicts between typical advice on this subject, and the results from a couple of select builds so I have to stop and ask a few questions.
(I wish * was still on here as a few of his posts (now a random deleted user acount #) seemed to indicate that he's given up on 50 degree valve angles almost entirely and I'd love to know why.)


Adam

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

Post by statsystems » Fri Jun 01, 2018 8:05 pm

NewbVetteGuy wrote:
Fri Jun 01, 2018 7:29 pm
statsystems wrote:
Fri Jun 01, 2018 7:12 pm
Yes, the time for 50* seats is here. Was here years ago.
Even on street builds? -At what max lobe lift would you recommend someone should go with a 50* seat (where's the tipping point)?


What about the longevity concerns? Can they be addressed? How? -What's the super rough difference in mileage between rebuilds with 45 deg and 50 degree seats?


50* just on the intake or intake and exhaust?


Adam

I really don't think lift is the defining factor in picking a valve job. Kinda like picking a cam using flow numbers only.

So far, I have not seen a decrease in service life between a 45* and a 50* seat. I do know you start beating on the valve train and the 50* doesn't take it as well. It's not as forgiving in that respect.

The other issue I've found is doing a 50* face on a valve originally cut with a 45* face. You remove so much from the margin just to get a seat on the valve. Those seem to have a shorter service life. With a minimum .060 margin the 50* appears as durable as a 45*.


IMO, a steeper seat is always beneficial in some cases. Number one is when the port is too damn small for valve diameter. You see this on Chrysler's. The port is already too small for the valve and the lift curve falls over at higher lifts. You can't get all that out with the valve job, but you can help it.

The other is more modern combustion chambers that are very close to the valve. IIRC Darin Morgan discussed this some here on ST, but that may have been pointed more towards a 55* seat.

At this point, where guys are building 400+ small blocks and are using conventional heads on them, I'd pick a 50* seat for all of them, flow numbers be damned.

Also, never neglect the top cut. It becomes even more important with steeper seats.

This is what I've found.

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

Post by Walter R. Malik » Fri Jun 01, 2018 8:18 pm

IF a large enough camshaft is used to take advantage of it ... certainly; Sometimes without more cam.

High in the chamber valve seats don't really like it much but, a somewhat sunken seat loves it.

Remember though ... EVERY engine combination is different.
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Re: 50 degree valve seats in modern hot street builds: is it finally time?

Post by Warp Speed » Fri Jun 01, 2018 9:42 pm

statsystems wrote:
Fri Jun 01, 2018 7:12 pm
Yes, the time for 50* seats is here. Was here years ago.

The problem is guys who live and die by flow bench numbers look at a 50* valve job say it won't work in a street car because low lift is down, and you only get it back until high lift.

I consider that an abuse of a flow bench.
It almost seems you change your point of view depending on who's giving it?!?

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

Post by statsystems » Fri Jun 01, 2018 9:58 pm

Warp Speed wrote:
Fri Jun 01, 2018 9:42 pm
statsystems wrote:
Fri Jun 01, 2018 7:12 pm
Yes, the time for 50* seats is here. Was here years ago.

The problem is guys who live and die by flow bench numbers look at a 50* valve job say it won't work in a street car because low lift is down, and you only get it back until high lift.

I consider that an abuse of a flow bench.
It almost seems you change your point of view depending on who's giving it?!?

Where did I say anything different? I've never said the flowbench was the end of everything.

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

Post by GARY C » Fri Jun 01, 2018 10:11 pm

NewbVetteGuy wrote:
Fri Jun 01, 2018 7:55 pm
SBC 350, 10.2:1 Static CR
Profiler 195cc heads (as cast); 2.01"/1.6" valves (PAC beehive springs * 10 deg steel retainers recommended by Mike Jones)
Cam: Mike Jones HR70375 -aggressive HR but not his noisy, REALLY aggressive lobes 227/228 @0.050 272/280 @0.006" .375"/.360" lobe lift (0.600"/0.576" with my 1.6RR)


Any guess what kind of increase I'd see if at next rebuild I moved to 50 degree seats?
How would you go about estimating such a thing?

(Danger: Newb making up not only #'s but calculations based upon nothing): Just roughly estimate +10 CFM at 0.500" - 0.600" lift? 273 CFM -> 283 CFM or a 3.7% increase; then take current ft lbs between 3,500 and 6,000 and multiply by 1.037 to end up with magical space math new torque estimates?!?

All baiting of the calculation nerds aside, I REALLY like super torquey street builds (I went with the strange aftermarket TPI-style "FIRST Fuel Injection" intake, the Profiler heads, a short-ish duration, high-ish lift cam, tri-y headers based build for that reason) and the idea of another 10-15 ft lbs everywhere in the curve and a bit of anti-reversion for going with a 50 degree seat angle valve, if I can still get 50,000 miles between rebuilds, sounds like the kind of trade-off I'd be happy to make.

-I see huge conflicts between typical advice on this subject, and the results from a couple of select builds so I have to stop and ask a few questions.
(I wish * was still on here as a few of his posts (now a random deleted user acount #) seemed to indicate that he's given up on 50 degree valve angles almost entirely and I'd love to know why.)


Adam
Keep in mind that if your port work and cam are optimized for a 45* seat just switching to a 50* could loose power, you always run that risk when changing something on a combo.
I would focus on the one you are going to run.
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THE ABOVE POST IN NO WAY REFLECTS THE VIEWS OF SPEED TALK OR IT'S MEMBER AND SHOULD BE VIEWED AS ENTERTAINMENT ONLY...Thanks, The Management!

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

Post by statsystems » Fri Jun 01, 2018 10:29 pm

GARY C wrote:
Fri Jun 01, 2018 10:11 pm
NewbVetteGuy wrote:
Fri Jun 01, 2018 7:55 pm
SBC 350, 10.2:1 Static CR
Profiler 195cc heads (as cast); 2.01"/1.6" valves (PAC beehive springs * 10 deg steel retainers recommended by Mike Jones)
Cam: Mike Jones HR70375 -aggressive HR but not his noisy, REALLY aggressive lobes 227/228 @0.050 272/280 @0.006" .375"/.360" lobe lift (0.600"/0.576" with my 1.6RR)


Any guess what kind of increase I'd see if at next rebuild I moved to 50 degree seats?
How would you go about estimating such a thing?

(Danger: Newb making up not only #'s but calculations based upon nothing): Just roughly estimate +10 CFM at 0.500" - 0.600" lift? 273 CFM -> 283 CFM or a 3.7% increase; then take current ft lbs between 3,500 and 6,000 and multiply by 1.037 to end up with magical space math new torque estimates?!?

All baiting of the calculation nerds aside, I REALLY like super torquey street builds (I went with the strange aftermarket TPI-style "FIRST Fuel Injection" intake, the Profiler heads, a short-ish duration, high-ish lift cam, tri-y headers based build for that reason) and the idea of another 10-15 ft lbs everywhere in the curve and a bit of anti-reversion for going with a 50 degree seat angle valve, if I can still get 50,000 miles between rebuilds, sounds like the kind of trade-off I'd be happy to make.

-I see huge conflicts between typical advice on this subject, and the results from a couple of select builds so I have to stop and ask a few questions.
(I wish * was still on here as a few of his posts (now a random deleted user acount #) seemed to indicate that he's given up on 50 degree valve angles almost entirely and I'd love to know why.)


Adam
Keep in mind that if your port work and cam are optimized for a 45* seat just switching to a 50* could loose power, you always run that risk when changing something on a combo.
I would focus on the one you are going to run.

You won't know unless you test it. How are you saying that an optimized port for 45* seats would lose power with a 50 unless you test it? The only way to test it is put in on a dyno and then take it to the track.

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

Post by swampbuggy » Fri Jun 01, 2018 10:30 pm

Adam.....This is what Brodix told me when i raised seat angle question to them, IF YOU ARE GOING TO DRIVE IT (" A LOT") stay with 45 degree seats. Mark H. :-k

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

Post by CGT » Fri Jun 01, 2018 10:39 pm

.580 to .650 lift hydraulic roller stuff with over 20k on it. There are alot of factors besides seat angle.
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Re: 50 degree valve seats in modern hot street builds: is it finally time?

Post by swampbuggy » Fri Jun 01, 2018 10:48 pm

CGT yes i agree and that thought passed through my mind as i was thinking about what all to type. Mark H. :)

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

Post by hoffman900 » Fri Jun 01, 2018 10:54 pm

To be fair, Brodix is covering their butt because most have no idea what they’re cobbling together. The other what is “a lot”? Is 20k a lot? The GM LS engine are going to go over 100k miles. That seems more like a lot to me, but it’s all relative.
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