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Old 10-04-2021, 09:21 PM
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I have seen some really good running Q-Jets over the years.
Same with Holleys. Has to do with who works on the things or
you just leave them alone.

Shaker455 is a GOOD Q-Jet builder if you ever need a rebuild.

Tom V.

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Old 10-04-2021, 09:46 PM
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Originally Posted by grandam1979 View Post
Your giving away et shifting that setup at 5200
Not in the slightest. You are giving up ET letting it go past 5500 RPM.
The heads are not big enough, cam is not big enough to have a prayer pulling to 6K.
Iron heads will not make power that high. Certainly not mildly ported 6X heads and a puny cam.

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Old 10-04-2021, 10:20 PM
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I ran a 6X head 455 for years it never went faster shifting at 5200 and 5500 was short shifting and it liked 5800 if you wanted to pull that last .10 out of it. Did you see he’s running a roller cam? His only restriction is the intake he didn’t say much about exhaust so that could be a factor. But again back to the original question what was his combination safe to again 6000 or less.

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Old 10-04-2021, 10:47 PM
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Quote:
Originally Posted by grandam1979 View Post
I ran a 6X head 455 for years it never went faster shifting at 5200 and 5500 was short shifting and it liked 5800 if you wanted to pull that last .10 out of it. Did you see he’s running a roller cam? His only restriction is the intake he didn’t say much about exhaust so that could be a factor. But again back to the original question what was his combination safe to again 6000 or less.

Ahh, I sure didn’t say anything about the exhaust. I’m currently running stock log manifolds with a Pypes 2.5” exhaust with x pipe and Race Pro mufflers.


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Old 10-04-2021, 10:53 PM
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Quote:
Originally Posted by Tom Vaught View Post
I have seen some really good running Q-Jets over the years.
Same with Holleys. Has to do with who works on the things or
you just leave them alone.

Shaker455 is a GOOD Q-Jet builder if you ever need a rebuild.

Tom V.

Thanks for the tip regarding Shaker455. I appreciate it!


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Old 10-04-2021, 11:07 PM
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Just for kicks, here’s a link to how it sounds.

https://youtu.be/RLA1BFHsbjc


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Old 10-04-2021, 11:38 PM
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For street fun, I’d shift at 5000. That engine is making huge power at that RPM, even without knowing. There’s little need to twist a 455 much more. If you make some track passes, you could experiment with different engine speeds, likely with little difference. You’re not competitively racing your Dads old car, just enjoying the heck out of it (finally).

Find out what all options the chassis dyno folks can provide during your session. They may have some sensors that can point you in a direction, if needed tuning wise.

Glad you are enjoying it!!!

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Old 10-05-2021, 12:48 PM
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I would start at 4500 and make runs. shift at 200 rpm increments, and log the runs.

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Old 10-05-2021, 02:36 PM
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I would put the chip redline chip at 5500 rpm.
Figuring out shiftpoints is the fun part..having a safe redline limit is more important. I ran stock rod 455's with zero issues for years..the biggest reason it lasted was a rev limiter or it would have grenaded many times.
My current engine has a 6500 redline limit for the valvetrain..and to be a few hundred rpms over shiftpoints.

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Old 10-05-2021, 03:24 PM
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To the OP, keep firmly in mind that on the street any motor will gain rpm the fastest and in turn accelerators the cars mass the fastest when it’s run in its torque band .

I am more then willing to bet that once you get the car on a chassis dyno that your most useful rpm range in that regard will be 3200 to 4700 at best!

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Old 10-05-2021, 04:35 PM
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Quote:
Originally Posted by grandam1979 View Post
I ran a 6X head 455 for years it never went faster shifting at 5200 and 5500 was short shifting and it liked 5800 if you wanted to pull that last .10 out of it. Did you see he’s running a roller cam? His only restriction is the intake he didn’t say much about exhaust so that could be a factor. But again back to the original question what was his combination safe to again 6000 or less.
I run a .265-.271, .690 lift SR, fully ported 197 HO heads, ported Warrior, 850, 2" headers, open ex.
Far more race oriented than the OPs street ride. many, many runs down the track to prove it.
You can not get enough air into the cylinder with his heads and cam to make power to 6K, not even close. Past 5500 RPM the piston is going down faster than the flame is pushing it.
Its a tq monster, use it and you do not have to worry about needless wear.
If I let my engine go past 6K on the 1-2 shift I am near 7K at the stripe and the car slows down.

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Old 10-05-2021, 05:05 PM
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Quote:
Originally Posted by Dragncar View Post
I run a .265-.271, .690 lift SR, fully ported 197 HO heads, ported Warrior, 850, 2" headers, open ex.
Far more race oriented than the OPs street ride. many, many runs down the track to prove it.
You can not get enough air into the cylinder with his heads and cam to make power to 6K, not even close. Past 5500 RPM the piston is going down faster than the flame is pushing it.
Its a tq monster, use it and you do not have to worry about needless wear.
If I let my engine go past 6K on the 1-2 shift I am near 7K at the stripe and the car slows down.
Nothing you just said has anything to do with his combination Again his combination is safe to 6000 or less.

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Old 10-05-2021, 05:16 PM
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Quote:
Originally Posted by Dragncar View Post
I run a .265-.271, .690 lift SR, fully ported 197 HO heads, ported Warrior, 850, 2" headers, open ex.
Far more race oriented than the OPs street ride. many, many runs down the track to prove it.
You can not get enough air into the cylinder with his heads and cam to make power to 6K, not even close. Past 5500 RPM the piston is going down faster than the flame is pushing it.
Its a tq monster, use it and you do not have to worry about needless wear.
If I let my engine go past 6K on the 1-2 shift I am near 7K at the stripe and the car slows down.
Where do you come up with this stuff?

Stan

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Old 10-06-2021, 12:33 AM
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Originally Posted by Stan Weiss View Post
Where do you come up with this stuff?

Stan
Dan Whitmore.
Have you been faster or quicker than me in the 1/4 mile with a Pontiac, iron heads and 9-1 CR ?
Let just say no and try and leave it at that.

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Old 10-06-2021, 12:41 AM
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Quote:
Originally Posted by Dragncar View Post
Dan Whitmore.
Have you been faster or quicker than me in the 1/4 mile with a Pontiac, iron heads and 9-1 CR ?
Let just say no and try and leave it at that.
I find it hard to believe someone as smart as Dan would say something as foolish as that.

Stan

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Old 10-06-2021, 09:09 AM
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The faster rate of piston speed will also result in a piston that travels quicker during the combustion cycle with less dwell time during spark ignition. A very high piston speed can cause the piston to move faster than the flame front during the combustion process resulting in a reduction of power.

http://www.rollingthunderz.com/rfs_f...n%20of%20power.


.

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Old 10-06-2021, 11:21 AM
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Quote:
Originally Posted by Steve C. View Post
The faster rate of piston speed will also result in a piston that travels quicker during the combustion cycle with less dwell time during spark ignition. A very high piston speed can cause the piston to move faster than the flame front during the combustion process resulting in a reduction of power.

http://www.rollingthunderz.com/rfs_f...n%20of%20power.


.
Steve,
While there are conditions where there can be flame front problem. I did not find that article that good in describing what is happening. But no where does he have the flame front pushing or no longer able to push on the piston.

Stan

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Old 10-06-2021, 11:59 AM
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"Mean and maximum piston speeds are still valuable calculations for any engine builder making a change to a proven formula. Exceeding 5,000 fpm in mean piston speed should get your attention and prompt rethinking on parts selection. Excessive piston speed can lead to inconsistent lubrication of the cylinder wall, and in some situations the piston will actually accelerate faster than the flame front during combustion. While the former can cause parts failure, the latter is lost horsepower."

https://blog.k1technologies.com/stok...ngle-explained


"With further increase in mean piston speed, the maximum power output and the power output at maximum thermal efficiency decreases."

https://www.sciencedirect.com/scienc...piston%20speed.


.

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Old 10-06-2021, 12:21 PM
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I know this is the street section. But just for reference John Langer is up around 7000.

Graph shows 3.75" stroke at different RPM up to 5000.

Stan
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Old 10-06-2021, 01:24 PM
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I certainly agree his engine internals will allow operation up towards 6000 rpm. That is setting aside his unknown valvespring specs that could leave the potential of the combo nosing over at rpm.
But I agree with the comments made here that his 'potential' peak power rpm certainly does not warrant shifting up in that realm.

As an example to support that, note the 5200 peak power rpm here in this combination below with a .050" duration cam. And NO, I'm certainly not suggesting it's apples-to-apples to the posters combo.
But I'll suggest it won't be a much higher rpm.

467 cid / 4.250" stroke
Unported KRE D-port heads
Crower hydraulic flat tappet cam #60919 w/1.65 rockers (0.517 lift)
Edelbrock RPM intake with Q-jet by Cliff Ruggles
Doug's headers



Here is the dyno sheet:https://pontiacstreetperformance.com/graphix/MikeG5.jpg

For conversation I would presume the KRE heads port volume is similar to the mild ported ported 6x-4 heads here in this thread. But probably not the airflow capability up through 0.600" lift as the KRE heads. While the roller cam here has the same .050" duration as the HFT cam it has more beneficial valve lift. And typical of a roller cam the power band, or operating rpm under which the engine is able to operate most efficiently, will increase from the 700 rpm as on the dyno sheet to 1000 rpm, or better. But his intake manifold and exhaust will certainly be a limiting factor.


.

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https://www.youtube.com/watch?v=qDoJnIP3HgE
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