Ported Chevy 083 heads, the tpi project

[Carnut1]

I feel in order to increase mass flow the csa has to go up around turns. What this does to the resonance I am not sure. Thanks

It will at least be more important than the resonance.

I like how you think. Thanks

[Carnut1]

I would think creating a curved roof on the intake port at the angle TPI meets the heads intake runner would make the resonance wave at that enlarged point, taller and slower, becoming misshapen…and probably dissipate the top… A larger resonance wave is slower than a small one so that part of the area would lag behind. So what does that mean when you’ve got 2 S turns and a 180 degree upward tube to go through all while changing your shape from rectangle, to square and to circular?

Probably not much given the big picture.

Of course, I could be totally wrong and everything I wrote is bull****. But at least it was articulate.

Funny!

[RobZ28]

What do you think of the intake manifold speeds on that Carnut? Thats probably the next question. Are they high? Low? Perfect? What does the pitot say on other intakes youve ported with good results? Thanks.

[Carnut1]

I think they are good for a street application or a tow truck. Plenty low and mid range torque. With a 700r and 3:27 gears traction in first will be an issue.

[Erland Cox]

First of all, with a full length TPI will maximum power come after 5500 RPM?
Some of the joy with the TPI is the incredible strength from low rpm, there are other manifolds for higher RPM.
How large is the engine going to be? A 400 definitively needs larger ports than a 350.
If we stay at 350 or 355 CI the engine will need around 200 CFM to reach 400 hp.
If that is at 5500 RPM we need app. 1.85-1.90 in minimum area.
My ported L98 head with 240 CFM is around 2.1 sqin at the push rod so there is no need to port that much.
My ported TPI port starts at 42mm high and ends at 43mm high, that is 1.65" 90 degrees to the wall and 1.69" where the port is eound.
Width goes from 29mm rectangular, 1.14" to 1,69" round.
I have tried as best as I could to measure corner areas and take width and height 90 degrees to the flow.
At the points that Charlie measured I have 1,85 sqin, 2.07-2.2 and 2,25.
So my runner tapers slightly.
Latervtoday I will try and flow my iron TPI heads and then see what I loose with the manifold base.
The curved runners to the plenum could be made from exhaust tube ans laser cut flanges.
1.69 ID is around 1,75 OD with 0,060" wall.
A lower 90 degree bend with a upper 90 degree bend that is 0ne size bigger maybe to build in some taper?
I have to look at what will fit.

Erland

[RobZ28]

I often dont want to say things here as I am a novice surrounded by some very smart people who do this for a living, but Im going to open my mouth here on the TPI ports (Airspeed and Depression) and I would think that on a typical carbureted engine, the airspeed for max RPM and sonic choke would be calculated for a higher RPM than TPI would. Therefore, less piston demand, less RPM, tuned intake runners and EFI should be able to tolerate more airspeed at lower RPM's due to the mathematical equations that are given by this board. Since you have done the tests without the runners I would be willing to bet WITH the curved runners that number would go down. This is in part why I was happy with the 350fps on the previous test. Am I off base here?

Here's Larry Meaux's reply from another thread on the matter for consideration.

-Begin Paste-
Quote:
In your calc. you use
"314.5 = Air velocity in Feet per Second " how is that measured, on the flow bench or engine?


its calculated or guesstimated
306.7 to 314.5 FPS range is about 1/2 the .55 Mach number (613.9
its represents the average port velocity baseline starting point
..you could use a number of your own to correlate your data

on the FlowBench, you would never "calculate or guesstimate" this
you would instead measure Port Velocity with a 180 degree or "U" or "J" shaped Pitot Probe attached to a 48" inch or so Vertical Manometer

the Pitot Tube would accurately account for Port's corner radius effects
..you can use equations to account for that, but the Probe is better/quicker/accurate

if your Pitot Probe Pressure in Inches of water "exceed" or equal your Test Pressure..theres are good chance you are already in or close to being into Choke under live conditions

you can get into a Choked port "sooner" than your Test Pressure number
..just depends how far the Choke's smallest-area is away from the
valve , and what are differences in pressure between the Short Turn Pressure and the Choke pressure

on the Short Turn's Apex you can flip the Pitot Probe upside down and attempt to measure localized velocity there on the apex...but that area seems to be worth 5 to 25 HP Losses if too high...but if the Port's Velocity in the smallest cross-sectional area is "too-high" its worth 50 to 100+ HP Losses..just depends on how far this area is from the valve

just like the Valve's Curtain Area in the Lift Curve will be the final Choke,
the Short Turn's Apex speed/pressure will be the next choke point,
then further up the smallest cross-sectional area Choke point

if you have a CA Choke point..it will control or dominate the port,..it will cause greater HP Losses than the Short Turn apex localized velocity

the straighter the Port (like a straight piece of tube)
the higher the velocity fps can be without flow separation or choke
the higher the fps...the higher the Volumetric Efficiency attainable

heads like #292 Turbo, #034 Bowtie, #461, #462, etc
all had "potential" pushrod area choke problems


Quote:
Can you please explain L/D ratios


the L/D Ratio is just

Valve_Lift / Valve_Diameter

.3732 Ratio = .724 Lift / 1.940 OD Intake valve


.4215 Ratio = 1.060 Lift / 2.515 OD Intake Valve

if you look at any Flow Curve...the Flow rate increase is pretty good until you reach .25 L/D Ratio..then the Flow rate increase really drops off

the older style heads with poorer design/shaped Ports, can't handle the air velocity as well as modern shaped ports...so increasing L/D Ratio above .37 to .39 usually shows no Dyno gains, and most times HP Losses above .39 L/D ...whereas, ProStock style heads like .41 to .42+ L/D Ratios

all you'll do with older heads above .39 L/D Ratio is slow down the Curtain Area velocity and increase the pressure differential between a possible choke point further up the Port ..like at the pushrod area ...causing the Port to go into Choke sooner in the Lift Curve.
_________________
Meaux Racing Heads
MaxRace Software
ET_Analyst for DragRacers
www.maxracesoftware.com

[RobZ28]

First of all, with a full length TPI will maximum power come after 5500 RPM?
Some of the joy with the TPI is the incredible strength from low rpm, there are other manifolds for higher RPM.
How large is the engine going to be? A 400 definitively needs larger ports than a 350.
If we stay at 350 or 355 CI the engine will need around 200 CFM to reach 400 hp.
If that is at 5500 RPM we need app. 1.85-1.90 in minimum area.
My ported L98 head with 240 CFM is around 2.1 sqin at the push rod so there is no need to port that much.
My ported TPI port starts at 42mm high and ends at 43mm high, that is 1.65" 90 degrees to the wall and 1.69" where the port is eound.
Width goes from 29mm rectangular, 1.14" to 1,69" round.
I have tried as best as I could to measure corner areas and take width and height 90 degrees to the flow.
At the points that Charlie measured I have 1,85 sqin, 2.07-2.2 and 2,25.
So my runner tapers slightly.
Latervtoday I will try and flow my iron TPI heads and then see what I loose with the manifold base.
The curved runners to the plenum could be made from exhaust tube ans laser cut flanges.
1.69 ID is around 1,75 OD with 0,060" wall.
A lower 90 degree bend with a upper 90 degree bend that is 0ne size bigger maybe to build in some taper?
I have to look at what will fit.

Erland

Erland, I look forward to your opinions on your manifold and seeing the lasered off flanges for bigger runners. Being around TPI and seeing all the things guys have tried over the years, I have zero doubts larger tube runners would allow even more airflow but the problems with doing this are 2 fold... 1) Too big and the bolt holes get in the way and the access to those fastners to assemble it become hard to get to. 2) The valve covers can also be an issue. Even with the Arizona Speed and Marine runners the valve covers have to be shopped to fit. The runner tubes will run into the covers themselves.

[Erland Cox]

The longer the ports are the more friction they will give.
The only way to lessen that friction is ti lessen air speed.
I have to look at plenum and everything to see what can be done.
I have a tig welder so building up the plenum and drilling new holes will not be a problem.
But I will do some air flow studies first staring with the manifold base.
On varying area along the runner. Every time there is an area difference there will be a reflection.
A long small taper will cause a weak reflection along its path but up and down areas will give conflicting reflections.

Erland

[RobZ28]

Test for thread, just got a message about adding pics.

[Erland Cox]

I did a flow test now with the most stock looking head that I could find.
It still flowed 227 CFM bare at .500".
With the ported TPI base added flow dropped to 206 CFM.
Looking at the port I believe that the biggest flow loss is the floor between the head and manifold with that angle.

Erland

[RobZ28]

I did a flow test now with the most stock looking head that I could find.
It still flowed 227 CFM bare at .500".
With the ported TPI base added flow dropped to 206 CFM.
Looking at the port I believe that the biggest flow loss is the floor between the head and manifold with that angle.

Erland

YES! That port angle is atrocious!! This is why Carnut raised the roof on the intake port. This has been what most guys do to try and offset that problem.

[skinny z]

First of all, with a full length TPI will maximum power come after 5500 RPM?
Some of the joy with the TPI is the incredible strength from low rpm, there are other manifolds for higher RPM.
How large is the engine going to be? A 400 definitively needs larger ports than a 350.
If we stay at 350 or 355 CI the engine will need around 200 CFM to reach 400 hp.
If that is at 5500 RPM we need app. 1.85-1.90 in minimum area.

What would be your opinion on a 302 CID engine? 4" bore x 3" stroke.
Not looking for high RPM such as the DZ 302 of the Trans Am series era. Just a smallish engine for the street that would use TPI induction. I'd often thought it would be reasonable fit. Now there's a fellow on another forum that is proposing to do just that.

[Tom68]

A low power 302, you could just get a 305 or better still a 307.

[skinny z]

A low power 302, you could just get a 305 or better still a 307.

Not necessarily low power but that's subjective really.
I'm thinking more the advantage of the larger bore which the 305 or 307 don't have.
Maybe a 2.02/1.60 valved Vortec head (modest flow but certainly enough for the smaller cubes). The TPI induction would help with the torque production as it has a reputation for. Not a lot of RPM needed for this particular application but 6k would be easy to come by I'd think.
Further to that, it's small and good fuel economy could be realized too especially if the boost in TPI torque is in a favourable spot.

Anyway, I don't want this thread to go astray from it's objective. I'm just throwing that out there to solicit an opinion or two.

[Doober]

Agreed, a 302/305 would still be capable taking displacement into consideration.

Great videos as usual Charles!

I'm wondering how the air will move after proper size runners are installed. Considering it will likely be fastest (guessing) as it rounds the tube into the base, would it help (or even be possible) to lower the floor as it reaches the head - similar to the sketches you drew from DV's explanation? It would obviously slow the air down to an extent, but might help direct it a little as it enters the head.

I figured the averages from your 3rd video and labeled each side, looking from the entry into the base... average on the floor is anywhere from 24-63fps faster than anywhere else.

A (floor): 315
B (right wall): 288
C (roof): 291
D (left wall): 252

I'm still very much an amateur, but learning a little bit every time I watch a video or read from someone like yourself that can actually explain how or why something is doing what it does.