cast dart 165cc test head for novice

[Carnut1]

Never use a radius on an intake seat, even if it flows more.

If you only test at 28 inches you won't learn much.

A flow bench is a tool. You can make it lie. Just because a port flows more on the bench doesn't mean it will make more power. See the first sentence.

Genuinely Interested in what you have to say STATSYS please teach. Want to understand how the radius affects differently from the flat cut 45 or where the radius comes up short. I always lap the seat on final prep this may soften the radius but not by much I am sure.

Radius under the seat is different than a radius seat.

[statsystems]

Never use a radius on an intake seat, even if it flows more.

If you only test at 28 inches you won't learn much.

A flow bench is a tool. You can make it lie. Just because a port flows more on the bench doesn't mean it will make more power. See the first sentence.

Genuinely Interested in what you have to say STATSYS please teach. Want to understand how the radius affects differently from the flat cut 45 or where the radius comes up short. I always lap the seat on final prep this may soften the radius but not by much I am sure.

That 4556 cutter will flow almost as good backwards as it does forward.

I think the OP would help himself a bunch if he just stuck to learning how to flow test a head, do it consistently and learn to develop a port before he gets into measuring air speed and using all the other bells and whistles. You will get information overload right quick.

Also, the OP needs to KNOW that flowing in one direction and at one test pressure is almost a waste of time. Before I ever measure air speed I flow at different pressures and work from that.

[GARY C]

Never use a radius on an intake seat, even if it flows more.

If you only test at 28 inches you won't learn much.

A flow bench is a tool. You can make it lie. Just because a port flows more on the bench doesn't mean it will make more power. See the first sentence.

Genuinely Interested in what you have to say STATSYS please teach. Want to understand how the radius affects differently from the flat cut 45 or where the radius comes up short. I always lap the seat on final prep this may soften the radius but not by much I am sure.

That 4556 cutter will flow almost as good backwards as it does forward.

I think the OP would help himself a bunch if he just stuck to learning how to flow test a head, do it consistently and learn to develop a port before he gets into measuring air speed and using all the other bells and whistles. You will get information overload right quick.

Also, the OP needs to KNOW that flowing in one direction and at one test pressure is almost a waste of time. Before I ever measure air speed I flow at different pressures and work from that.

True! knowing how to use the data is more important then having the data and will take years of testing flow vs dyno vs track... Rinse and Repeat.

[groberts101]

True! knowing how to use the data is more important then having the data and will take years of testing flow vs dyno vs track... Rinse and Repeat.

Exactly! But how the hell can the op be expected to do all that and get his racecar back together within the next 2 years?

C'mon guys.. there's the perfect ideal.. and then there's the reality of what a newcomer can achieve in shorter order. Maybe just help fast track the guy towards improving what he can over what he had. From his other thread the car was already decent as it was, so why not help him make the basic and elementary improvements he was originally looking for to begin with?

That will get him near 90% of the way towards an idealized port design anyways. The last 10% will take far longer due to the ever increasing learning curve that will be involved to get there.

[user-30257]

I see in the second and third picture is where I would start. Do a 30 degree back cut on the intake valves.

why not back cut the valve to the same angle as the top cut for starts?

Huhh Back cut implies its the second cut on the back side of the intake?

Yes. As in if the top cut of the valve job is 38, the back cut of the valve is 38.

[groberts101]

In a moderately well designed port wouldn't you expect the flow to approach and sometimes pass supersonic as it goes past the seat section minimizing the shear or grab effect?

Seriously?.. on an intake port?

Please teach me how to do that!.. I have money!

[user-17438]

In a moderately well designed port wouldn't you expect the flow to approach and sometimes pass supersonic as it goes past the seat section minimizing the shear or grab effect?

Seriously?.. on an intake port?

Please teach me how to do that!.. I have money!

Can i have your money? I'm a little low on it myself. lol.... j/k

[af2]

Would you think at Mach a way to disrupt would be shear?
Goes back to a rectangle port intake on an oval head?

[groberts101]

In a moderately well designed port wouldn't you expect the flow to approach and sometimes pass supersonic as it goes past the seat section minimizing the shear or grab effect?

Seriously?.. on an intake port?

Please teach me how to do that!.. I have money!

Can i have your money? I'm a little low on it myself. lol.... j/k

You'll have to generate some crazy ass fake flow sheets and get me drunk enough to fall for them first!

[user-17438]

Seriously?.. on an intake port?

Please teach me how to do that!.. I have money!

Can i have your money? I'm a little low on it myself. lol.... j/k

You'll have to generate some crazy ass fake flow sheets and get me drunk enough to fall for them first!

I wasnt going to show you anything. i was just interested in the money. lol

[groberts101]

Can i have your money? I'm a little low on it myself. lol.... j/k

You'll have to generate some crazy ass fake flow sheets and get me drunk enough to fall for them first!

I wasnt going to show you anything. i was just interested in the money. lol

LOL.. now you sound like my wife! That's what happens when you stay married to the same one for too long.

[B Original]

Hypothetical calculation If you have an average port speed in a 2.2 square area of 300 fps at .200 how fast do you think the air speed is flowing past the curtain area at .200 lift = about .64 square area ? 2.2/.64=3.44 so 3.44x300 fps is 1032 fps.
1X mach speed is 1125 fps. "near or past mach speed at the seat"? Not disputing you about the radius below the seat tho.

Not here to prove someone else wrong just presenting what I understand wanting to learn if I am mistaken so don't beat me up too bad

[steve cowan]

forgot to mention i have not checked a as cast port yet,have not checked the exhaust just wanted to share what i have at the moment.
i checked intake with no valve went 214
with the valve at 0.600'' went 217 cfm is this because the air went turbulent out of the seat area??? thanks

Did you put a valve in from the top to account for the stem or no valve at all?

Gary,
I turned the valve upside down, it didn't encroach past the bottom of guide, greased stem to stop leakage,

[GARY C]

True! knowing how to use the data is more important then having the data and will take years of testing flow vs dyno vs track... Rinse and Repeat.

Exactly! But how the hell can the op be expected to do all that and get his racecar back together within the next 2 years?

C'mon guys.. there's the perfect ideal.. and then there's the reality of what a newcomer can achieve in shorter order. Maybe just help fast track the guy towards improving what he can over what he had. From his other thread the car was already decent as it was, so why not help him make the basic and elementary improvements he was originally looking for to begin with?

That will get him near 90% of the way towards an idealized port design anyways. The last 10% will take far longer due to the ever increasing learning curve that will be involved to get there.

The way he is doing it, start with a baseline car, getting help on the porting and then retest and keep learning. Thats how I started, I couldn't afford dyno testing on top of everything else so i did what I could at the track and then just tried different things and learned from others around me.

[GARY C]

forgot to mention i have not checked a as cast port yet,have not checked the exhaust just wanted to share what i have at the moment.
i checked intake with no valve went 214
with the valve at 0.600'' went 217 cfm is this because the air went turbulent out of the seat area??? thanks

Did you put a valve in from the top to account for the stem or no valve at all?

Gary,
I turned the valve upside down, it didn't encroach past the bottom of guide, greased stem to stop leakage,

normally you want the stem to go through as if the valve is in but it eliminates the valve head influence.