Frankshaft wrote: ↑Wed Jun 13, 2018 2:18 pm
I remember that article. It was in Drag Racing illistrated. It was multiple parts. It never got finished, dynoed, or whatever. I remember them responding in the question and answer section. Might have been a slug, and they said, can't publish this, who knows. With that seat profile, I could see it being a slug.
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.
Please Note!
THE ABOVE POST IN NO WAY REFLECTS THE VIEWS OF SPEED TALK OR IT'S MEMBERS AND SHOULD BE VIEWED AS ENTERTAINMENT ONLY...Thanks, The Management!
Please Note!
THE ABOVE POST IN NO WAY REFLECTS THE VIEWS OF SPEED TALK OR IT'S MEMBERS AND SHOULD BE VIEWED AS ENTERTAINMENT ONLY...Thanks, The Management!
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.
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.
Who cares
Tom
I guess the person that brought it up on the last page.
Please Note!
THE ABOVE POST IN NO WAY REFLECTS THE VIEWS OF SPEED TALK OR IT'S MEMBERS AND SHOULD BE VIEWED AS ENTERTAINMENT ONLY...Thanks, The Management!
Rick360 wrote: ↑Mon Jun 11, 2018 10:06 pm
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
when you define an area the flow needs to be normal to the area in question for it to be relevant. the flow will not necessarily follow a path that is normal to the blue line
Last edited by digger on Thu Jun 14, 2018 7:59 am, edited 1 time in total.
You would think that he would of supplied the original (first time on the dyno) carb dyno sheet, but I guess a picture of some mufflers will have to do.
DrillDawg wrote: ↑Thu Jun 14, 2018 7:50 am
You would think that he would of supplied the original (first time on the dyno) carb dyno sheet, but I guess a picture of some mufflers will have to do.
I didn't ask him about that, that pic is one I pulled from his ex article. If the final part was already submitted to the mag company then they would have control of that. I doubt he would still have it 20 years later and is probably no longer running a floppy drive to access it if he did.
Please Note!
THE ABOVE POST IN NO WAY REFLECTS THE VIEWS OF SPEED TALK OR IT'S MEMBERS AND SHOULD BE VIEWED AS ENTERTAINMENT ONLY...Thanks, The Management!
Rick360 wrote: ↑Mon Jun 11, 2018 10:06 pm
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.
Rick
when you define an area the flow needs to be normal to the area in question for it to be relevant. the flow will not necessarily follow a path that is normal to the blue line
Not sure I know what you are saying. When the valve is at the point where the blue line is creating the minimum curtain area is probably when the valve curtain area is bigger than the size of the throat area.
The flow should be generally perpendicular to the blue line.
High speed air flows at line of sight for lack of better description. I'll post some things to show what I mean when I get a chance. This empasises more strongly why 50 is better at higher lifts and how the chamber matters a lot.
I have seen several reports that more ideal chamber shapes can make more power when tested on the engine, yet flowbench may same the same or worse.
How can that be? well,
maybe the flow IN the cylinder, is different on the real engine then can be seen with a flowbench.
In fact, you KNOW it must be so.
digger wrote: ↑Thu Jun 14, 2018 9:35 pm
High speed air flows at line of sight for lack of better description. I'll post some things to show what I mean when I get a chance. This empasises more strongly why 50 is better at higher lifts and how the chamber matters a lot.
Sure. Shape is king but it go's far deeper than that. Aside from the curtain to csa convergence point mentioned earlier there is also a transition point within the lift range where seat shape has less impact and valve shape contributes a greater portion to the shape and length of the flow cone as well.
digger wrote: ↑Thu Jun 14, 2018 9:35 pm
High speed air flows at line of sight for lack of better description. I'll post some things to show what I mean when I get a chance. This empasises more strongly why 50 is better at higher lifts and how the chamber matters a lot.
Sure. Shape is king but it go's far deeper than that. Aside from the curtain to csa convergence point mentioned earlier there is also a transition point within the lift range where seat shape has less impact and valve shape contributes a greater portion to the shape and length of the flow cone as well.
Huuuuuuuyup.^^^^^^^^^^^^^^
So it's more than just the seat angles themselves. It's part of the package of the entire valve job.
Seems to me (no math to back this up so I wing it) if you start the air flow around the valve with a better shape you will continue that as the valve moves away from the seat.
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.
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
When I have pitot tested intake valves the flow from the seat towards the chamber always lets go at some lift on the port side.
Just like the air cannot make that turn at high velocity.
Maybe the better high lift flow from steeper seats comes from the flow not separating as easy from the seat with steeper angles?
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.
