470 going to the dyno - HP/TQ estimates
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This has been a worry of mine to be honest. We run a solid street roller in my dads car and it has been awesome. People in my sphere have sworn by the hydraulic rollers, so we will see how it does. If the lifters start to to get unhappy before 6K, I can always change to solid rollers, although I would have to buy new pushrods. Guess I'll finds out in a few days.
Can't wait. Good luck
That's what I was thinking as well. Maybe someone on the board will know. The receipt says "906 Port". Here is the flow sheet for the heads. Numbers seem high to me for a STD port head, but I am not an expert.
Thanks!
Yeah that would be a great port if standard, it does have big valves though.
I guess one way to tell if it's max wedge, I would imagine the runners on the intake may need to be welded on the outside, I could be wrong but my tunnel ram required welding on the exterior just so I could get the Hughes standard port gasket to not break through when I ported it.
PRH
Well-Known Member
I hesitate to even bring this up, since it usually turns into a pi$$ing contest……
The whole flow sheet is completely suspect…….because of the flow rate listed at .100 lift.
This isn’t me being butt hurt because the numbers are so much better that what I get……..it’s because the flow number is “impossible”………and not by a little bit either.
The airflow through a head at 28” of test pressure will only yield so many cfm per sq/in of area.
That number is 149cfm per sq/in.
The curtain area created by a 2.19 valve lifted .100” is .688 sq/in.
149 x .688 = 102.5cfm.
The sheet shows 150cfm.
Can’t happen…….it’s a fantasy.
Not only that, I’ve never tested any head that got anywhere even close to a discharge coefficient of 100%.
A head with decent flow at .100 lift rarely gets over 80%.
Up to the .300-.400 lift range, the flow is mostly impacted by the valve diameter, shape, and valve seat shape.
The TF heads have the same size intake valve, and a valve and seat shape that results in decent low lift flow.
At .100 lift…….they flow in the low 70’s(c/d of about 70%).
Even at .200 lift the SR flow sheet is showing a flow rate of over 100% c/d.
Keep in mind, it cannot be over 100%
The TF heads are about 76% at .200 lift.
If I flowed the OP’s heads here, I guarantee the flow numbers would be significantly different.
However, in its current form, the head flows what it flows, regardless of differing flow results from different benches.
Lower flow results from a different bench doesn’t make the head itself any less capable.
If bench A says 350, and bench B says 300……….for the same head………the dyno really doesn’t care.
The whole flow sheet is completely suspect…….because of the flow rate listed at .100 lift.
This isn’t me being butt hurt because the numbers are so much better that what I get……..it’s because the flow number is “impossible”………and not by a little bit either.
The airflow through a head at 28” of test pressure will only yield so many cfm per sq/in of area.
That number is 149cfm per sq/in.
The curtain area created by a 2.19 valve lifted .100” is .688 sq/in.
149 x .688 = 102.5cfm.
The sheet shows 150cfm.
Can’t happen…….it’s a fantasy.
Not only that, I’ve never tested any head that got anywhere even close to a discharge coefficient of 100%.
A head with decent flow at .100 lift rarely gets over 80%.
Up to the .300-.400 lift range, the flow is mostly impacted by the valve diameter, shape, and valve seat shape.
The TF heads have the same size intake valve, and a valve and seat shape that results in decent low lift flow.
At .100 lift…….they flow in the low 70’s(c/d of about 70%).
Even at .200 lift the SR flow sheet is showing a flow rate of over 100% c/d.
Keep in mind, it cannot be over 100%
The TF heads are about 76% at .200 lift.
If I flowed the OP’s heads here, I guarantee the flow numbers would be significantly different.
However, in its current form, the head flows what it flows, regardless of differing flow results from different benches.
Lower flow results from a different bench doesn’t make the head itself any less capable.
If bench A says 350, and bench B says 300……….for the same head………the dyno really doesn’t care.
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I'm looking forward to the results.
Yeah me too
I hear what you are saying. I have found other ported SR heads that flowed about the same as the sheet says online. At the end of the day, the ports look great on these heads and we will see what the dyno says. I dropped it off at Koffel's this morning.
I've got a call out to our local flow bench operator and porter.
He's worked many Indy heads.
He's worked many Indy heads.
Just a couple updates. Scott Koffel and I talked this morning when I dropped off the motor. He seems to be easy to deal with and knows what he is talking about. That being said, I am more concerned than ever about the hydraulic roller lifters. Mine are Trickflows purchased on 2021, so I believe are actually Morels. Scott relayed that they have had issues with hydraulic roller lifters on the dyno, but not the instability issues that others have mentioned. Basically lifter plunges getting stuck due mainly to tolerance issues with the lifters. He said this was mainly with comp hydraulic roller lifters, so I am keeping my fingers crossed that I won't have this issue. Motor should be ready for some pulls tomorrow.
Why does it say the same cfm all the way across from low to high lift? Or am I totally miss reading this?
We all wish you luck, it is a stressful period of time. I just about threw up, when Dyno time came for my 470 2nd time around.
Lower on the sheet under range.
PRH
Well-Known Member
I’m not saying the OP’s heads can’t flow 350 at the high lifts.
What I’m saying is the low lift numbers are an impossibility.
So, in order for the high lift numbers to be correct, whatever situation is creating the false low lift numbers…….that issue would have to cure itself at high lift.
Just doesn’t seem like like a realistic scenario.
What I’m saying is the low lift numbers are an impossibility.
So, in order for the high lift numbers to be correct, whatever situation is creating the false low lift numbers…….that issue would have to cure itself at high lift.
Just doesn’t seem like like a realistic scenario.
I could believe 150 cfm starting @ .200
PRH
Well-Known Member
The “450” on the intake and “315” on the exhaust are the test range.
The number below it is the percent of flow.
So, at .100 lift intake, you have 34% of 450 = 153.
PRH
Well-Known Member
Sure…….but the over 100% c/d isn’t happening on the exhaust side.
And [email protected] on the exhaust would be quite low.
The main point of my original post was that there are obvious red flags on the sheet………enough to where the validity of the results are questionable and/or impossible.
TT5.9mag
Two atmospheres are better than one
If they are Morels you have a much better chance of success. Were they disassembled, inspected, cleaned and reassembled prior to being put in use?
Just a little reassurance maybe, the hydraulic roller lifters in my BBC were dead stable to 6700 on the dyno, and while I dont turn it that hard in the boat, it has been to 6200 many times. They are factory gm replacement hydraulic lifters. Good oil control and pressure is important.
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