Any turn down a 1.09" 30 degree intake valve to grind it 45 degree ??

[winr1]

Also, any experiment with a 35* or 40* intake valve as to flow ??


And, intake valve, how far to edge can one take the contact point  ??



Ricky.

[Barry_R]

yes

within .010

[winr1]

Thanks much Barry !



Ricky,

[plovett]

Here are 30 degree intake seats vs. 45 in the same head with the same valves, same flow bench.

Lift-----30-degree---45 degree
0.050----36.0---------26.9
0.100----72.1---------61.7
0.200---141.9-------129.3
0.300---193.0-------190.4
0.400---222.7-------236.1
0.500---259.6-------267.3
0.550----------------281.3
0.600---278.6-------293.4
0.650---279.8-------302.8

These were ported Edelbrocks with 2.09" Ferrea valves.

paulie

[winr1]

Thanks much Paulie, I saw you post those before but did not remember

Wonder what the same valve and 30 versus 45 in a cast iron small port head with bowl work would flow ??



Ricky.

[plovett]

Thanks much Paulie, I saw you post those before but did not remember

Wonder what the same valve and 30 versus 45 in a cast iron small port head with bowl work would flow ??

Ricky.

I would think the trends would be the same, but the flow would about 240-250 cfm at higher lifts.  Maybe one of the head porter or engine builder guys knows? 

Bottom line, in my opinion, is what you choose depends mostly on your cam.  If you have factory CJ cam with .481" lift, then a 30 degree seat is likely better.  If you have an aftermarket cam with .600" lift then a 45 degree seat is better.

The 35 or 40 degree seat is an interesting idea. 

paulie

[CaptCobrajet]

There is more to it than just the seat angle.  The angles above and below the seat, and the width of those angles, can really make a huge difference.  Custom made 5, 6, even 7 angle cutters with 30 and 40-ish seat angles can be better than 45 stuff.  Especially with a lower lift camshaft up to around .600 lift.

[gt350hr]

 I would thing the bottom line is how it performs on the track. I've seen flow bench improvements that don't relate to ET reduction OR mph increases.
    Randy

[Rory428]

I would thing the bottom line is how it performs on the track. I've seen flow bench improvements that don't relate to ET reduction OR mph increases.
    Randy

Absolutely agree. I have also seen guys "find" 15-20 HP on the dyno, but once they put the engine back in the car, there is no improvement, and in some cases, they actually run slower, with more supposed HP. A combination has to all work together. Adding power up high, at the expense of lower RPM is often a path to disappointment. We have all seen guys who have spent a bunch of $$$$ on the latest and greatest "Whiz Bang" trick of the week parts, that get their butts kicked by a milder, but well sorted out combination.

[plovett]

Yeah, you could say the track is the ultimate flowbench.  The more air the engine can actually process while in the car and accelerating down the track, the faster it will go.

That said, flow benches are very useful in my opinion.  And I don't think a 45 degree seat angle is anything trick.

JMO,

paulie

[Joe-JDC]

Say what you may about flow benches, but after using them for the last 28 years, I have found a lot of things that look good, that didn't work, and things that looked wonky worked like gang busters.  Also found that by using the bench to test back to back, you could find 10-20-30 cfm by changing a simple angle of the port floor, or short turn.  If I had not had the flow bench, I would have never known the 30 extra cfm was there to be had.  Also, with proper adapters, I have been able to flow intake manifolds, plenums, and exhaust manifolds, carbs, etc. to find what was an actual improvement over what simply looked good.  I have flowed Wilson mainfolds that cost over $2500.00 that had variances of 80 cfm from runner to runner, and Hogan sheetmetal tunnel rams with one dead runner.  Without the flow bench, those problems would not have been found and repaired.  A flow bench, dyno, or chassis dyno is only as good as the techniques used with experience to be repeatable.  Joe-JDC

[Barry_R]

Have to agree with Joe here.  While anybody that has been involved in this stuff long enough can cite individual cases where a dyno or flow bench gain was not backed up by on track performance, there are way more instances where the gains were verified.  Its probably that old 80-20 rule deal again.  If you see a statistically significant AVERAGE improvement IN THE RANGE WHERE THE ENGINE OPERATES, there is a darn good chance you will see that translated to ET and MPH.  This means that if you trade a loss in most of the range for the Hollywood number at the very peak you might slow down or show nothing.  It also means that if your combination was highly refined to get the most out of a given combination, you may have to do some development to the rest of the car to see any gain materialize if it came from a higher RPM band etc.

The 45 degree reference angle for a valve job is hardly new or trick in any way.  Its been the defect industry standard for pretty much everything built for the past 45 years or so - including Ford.  This in no way means that you cannot get very good results from a highly developed 30 degree package.  But everybody who was using that angler in the 60s and 70s (Ford, Pontiac, Olds) went the other way a long time ago, as has every racer that was not limited by a specific rulebook.  As Blair alluded to, your results may have more to do with the angles above and below the seat than with the sealing surface itself.

[plovett]

Just rambling here…..but I think high lift flow is more important on the intake side and low lift is more important on the exhaust side, because of the pressure differentials in relation to valve events and lifts (not really considering overlap)  I am sure that is a gross oversimplification, but...….

JMO,

paulie

[gt350hr]

 Paulie
     It's important to look at the whole picture . There are trade offs for changes. In recent years Nascar engine ( and high rpm drag race engine) builders migrated toward a 55* seat angle as it improved high lift/rpm air flow.  To do that on a 6,000 rpm engine with .500 lift "might " not be the best choice but at 9,000 and .700 or more lift , it works.


 Joe and Barry,
      I agree a flow bench has great value , Unfortunately the testing is not done as if the engine was operating. Look at the changes in porting techniques when "wet flowing" was created. We test air flow with a static valve at a specific lift with a depression that "in the real world" changes as the rpm fluctuates , and mostly with "dry" air often without regard to the manifold and carburetion being used. In reality you have MANY variables in the "air pump" below the head that have major impact on it's performance. Exhaust ports aren't flowed under true operating conditions either. If they were , we would have hot , still burning air exiting and "some" vacuum pull (simulating header scavenging) on the port which could have  serious affect on flow numbers. A perfect example is the 351C head. When "pushing" unheated air out of the port it shows poor bench numbers. Adding vacuum on the flange side does wonders for picking up the flow numbers. I didn't find this on my own , it came from a retired Ford Engine dept engineer I was talking to many years ago. He called the flow bench a "relative tuning aid" and offered that a Spintron style device could be used to turn an engine over and get more realistic information.
  I'm not a flow bench hater by any means , I just know they don't have slicks attached to them LOL.
       Randy

[winr1]

Thanks for the replys guys !!



Ricky.