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Bowl sizing questions
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steve cowan
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Re: Bowl sizing questions
Brad,BradH wrote: ↑Sat Dec 21, 2019 2:18 am I can post links to other threads that go into more details about the car, engine, etc. The quick overview is that it's a 3800# (with driver) street/strip car powered by a 452 ci BB Mopar. Old engine made a bit over 600 HP and the car ran mid-to-high 10s. New combination picked up 60+ HP with better heads and switching from .600" sft to .650" solid roller with same basic 266 at .050 duration and same 108 LSA.
Engine now has Edelbrock Victor heads with standard port size and 2.20" intakes. Measurements of max bowl diameter of same type of head, or a Procomp clone, prepped by different people / shops for reference to my original question. All the ported runners flow in the 340-360 range with MCSA of 2.6+" to about 2.8", and average CSA of 2.7" to 2.9". The port with the largest CSAs was not the best in terms of peak or average flow as tested up to .750" lift.
Procomp unported - 1.96"
Procomp ported by me - 2.04"
Procomp ported by PRH - 2.07"
CNC Victor from shop that specializes in Mopar (largest runner checked) - 2.05"
Latest version of Victor unported - 1.89"
Latest version of Victor ported by PRH - 2.07"
What I have in mind is to do the next set with more emphasis on stable high-lift flow, even if there is some tradeoff in low(er) lift. I was thinking this would be complimented by a cam of similar duration that had closer to .700" lift.
have you talked to PRH about different seat angles in your application??
i see the other thread about Mopar cylinder heads there is a comment saying indy heads dont like a steeper seat angle,i have no experience with mopar so just curious
steve c
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mag2555
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Re: Bowl sizing questions
You need to evaluate the whole head port your looking to rework and its wall thickness, not just the valve bowl.
If for example you are shotting for a Intake bowl Throat of 90% of your Intake valve which lets say comes out to 1.850" then the rest of your port circumference needs to be able to be taken up to 5.809".
This is a minimum circumference number as with heads of under a 18 degree valve inclination angle you may need to go larger so you can get a larger expansion rate over the short turn to slow down the air mass.
Also from this 1.850" Throat diameter the overall height of the short turn from the end of the bottom cut in bowl to the crown of the short turn needs to be a absolute minimum of a 925" arc.
If you do not have this overall short turn height to work with then atleast aftermarket heads and some iron factory should have the needed meat to allow you to layback the short turn arc to the new needed arc/ radius.
Here's a picture of how much I needed to lay back / re-arc a Ford iron 2 bbl Cleavland head from stock to get within 10 cfm of 300 cfm.
Compare the stock valve bowl left with the back lit Orange one.
If for example you are shotting for a Intake bowl Throat of 90% of your Intake valve which lets say comes out to 1.850" then the rest of your port circumference needs to be able to be taken up to 5.809".
This is a minimum circumference number as with heads of under a 18 degree valve inclination angle you may need to go larger so you can get a larger expansion rate over the short turn to slow down the air mass.
Also from this 1.850" Throat diameter the overall height of the short turn from the end of the bottom cut in bowl to the crown of the short turn needs to be a absolute minimum of a 925" arc.
If you do not have this overall short turn height to work with then atleast aftermarket heads and some iron factory should have the needed meat to allow you to layback the short turn arc to the new needed arc/ radius.
Here's a picture of how much I needed to lay back / re-arc a Ford iron 2 bbl Cleavland head from stock to get within 10 cfm of 300 cfm.
Compare the stock valve bowl left with the back lit Orange one.
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You can cut a man's tongue from his mouth, but that does not mean he’s a liar, it just shows that you fear the truth he might speak about you!
Re: Bowl sizing questions
I checked a couple bowls of the “bare” head you sent here....... I didn’t write it down, but I’m pretty sure I came up with a number lower than 1.89.
I have a feeling we aren’t measuring the same place.
Plus, those bowls are shaped like a funnel...... the farther in you go, the smaller it gets.
The set I ported for you started out with the intake bowls in the 1.75 range.
Those were just stupid small, and pretty core shifted as well.
As a counter point to the Victor head, the Performer RPM head comes with the bowls at right about 2.050 for a 2.140 valve.
I have a Speedmaster RPM copy here...... the bowl I just just checked is 2.020.
A MCH cnc ported Stealth head has the intake bowl at 2.095.
A Hughes MW “maxx” cnc version of those heads I had here had the bowl at 2.23”(these start out with the bowls cast a fair amount bigger than the Gen 2&3 std port version.
Those particular Hughes heads had 2.19” intake valves.
The TF heads have the bowls at 2.19 for a 2.19 valve...... as do several of the Indy BB heads I’ve checked that they cnc ported.
EZ295, SR295, 440-1 cnc325 & cnc345.
I have a feeling we aren’t measuring the same place.
Plus, those bowls are shaped like a funnel...... the farther in you go, the smaller it gets.
The set I ported for you started out with the intake bowls in the 1.75 range.
Those were just stupid small, and pretty core shifted as well.
As a counter point to the Victor head, the Performer RPM head comes with the bowls at right about 2.050 for a 2.140 valve.
I have a Speedmaster RPM copy here...... the bowl I just just checked is 2.020.
A MCH cnc ported Stealth head has the intake bowl at 2.095.
A Hughes MW “maxx” cnc version of those heads I had here had the bowl at 2.23”(these start out with the bowls cast a fair amount bigger than the Gen 2&3 std port version.
Those particular Hughes heads had 2.19” intake valves.
The TF heads have the bowls at 2.19 for a 2.19 valve...... as do several of the Indy BB heads I’ve checked that they cnc ported.
EZ295, SR295, 440-1 cnc325 & cnc345.
Last edited by PRH on Sat Dec 21, 2019 10:46 am, edited 1 time in total.
Somewhat handy with a die grinder.
Re: Bowl sizing questions
We're probably not checking in the same locations or in the same way. I took two different sets of measurements, the first from about 1.5" down from the seat (about the height of the guide) and as in the same plane as the valve stem as I could, and the second ones which were simply looking for the max bowl diameter, and are the ones I provided above.
The first measurements may still not be in sync with yours, but here's what I came up with.
Procomp as cast - 1.75"
Procomp my port - 1.93"
Procomp your port - 1.98"
PRH ported Victors - 1.99" +/-
Victors as cast - 1.69" +/-
The first measurements may still not be in sync with yours, but here's what I came up with.
Procomp as cast - 1.75"
Procomp my port - 1.93"
Procomp your port - 1.98"
PRH ported Victors - 1.99" +/-
Victors as cast - 1.69" +/-
Last edited by BradH on Sat Dec 21, 2019 11:25 am, edited 1 time in total.
Re: Bowl sizing questions
On most Heads I’m looking for the largest measurement I can get to determine what the max diameter is(down into the bowl, not up near the seat ring), but the std port victors don’t have the bowls shaped like any other aftermarket head I can recall working with(it reminds me of some stock 2.11 valve Pontiac heads where the valve is pretty big, but the bowl is tiny).
As I said previously...... they’re just like a funnel(the farther in you go, the smaller it gets)....... so on those I usually take the measurement about where the guide ends....... but closer to the roof is smaller/closer to the seat is bigger...... by a fair amount.
Imo, a complete clusterfuck of a size/shape to start out with for something that’s supposed to be a “race” head.
I can’t imagine someone being able to give me a logical reason that made any sense as to why it’s made that way.
As I said previously...... they’re just like a funnel(the farther in you go, the smaller it gets)....... so on those I usually take the measurement about where the guide ends....... but closer to the roof is smaller/closer to the seat is bigger...... by a fair amount.
Imo, a complete clusterfuck of a size/shape to start out with for something that’s supposed to be a “race” head.
I can’t imagine someone being able to give me a logical reason that made any sense as to why it’s made that way.
Last edited by PRH on Sat Dec 21, 2019 11:01 am, edited 1 time in total.
Somewhat handy with a die grinder.
Re: Bowl sizing questions
Let's see if I can post pics without breaking something...
As cast Victor bowl & short turn with PRH valve seats cut.
As cast Victor bowl & short turn with PRH valve seats cut.
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Last edited by BradH on Sat Dec 21, 2019 11:12 am, edited 1 time in total.
Re: Bowl sizing questions
My Procomp bowl and short turn.
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Re: Bowl sizing questions
PRH Procomp bowl and short turn.
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Re: Bowl sizing questions
PRH ported Victor bowl & short turn + I hit the bowls with a rougher carbide texture.
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Re: Bowl sizing questions
Also for reference, some pics of Chapman Mopar Stage VI. Unfortunately, I can't locate the other Chapman pics that show how much the bowl expands below the seat as viewed from the runner entry.
EDIT: Found it...
EDIT: Found it...
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Last edited by BradH on Sat Dec 21, 2019 12:05 pm, edited 1 time in total.
Re: Bowl sizing questions
Brad, how about a pic of the new head, with you’re measuring tool in place where you’re taking the measurement.
On the heads I did for you, I made the bowls .300” bigger than as cast........ as measured centered on the guide and even with the end of it height wise.
Here’s an ootb EZ head...... 2.060-2.070:
On the heads I did for you, I made the bowls .300” bigger than as cast........ as measured centered on the guide and even with the end of it height wise.
Here’s an ootb EZ head...... 2.060-2.070:
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Last edited by PRH on Sat Dec 21, 2019 12:35 pm, edited 2 times in total.
Somewhat handy with a die grinder.