How High do we Buzz the motor?

SST159 · 10-24-2012, 12:20 PM

Interesting question for Y'all!
I know there are many factors that go into play of answering this question which is:
When putting together an engine combination, how does one figure how high the motor could be and should be reved affectively and safely.
Are there any formulas out there which help with baseline shift points and trap RPM based on the engine and its components? I am putting together a SBC 401 CU using good parts, Callies crank, Manley Pro lite rods etc. The stroke will be 3.750 and will be using 6" rods.
Thanks.

Dave Steltz · 10-24-2012, 03:53 PM

Huh ? You use a tach ? Ya'll ? You coming down south with me ??

I'd say for you 9500 is a good starting point...lol...

On a more serious note alot of engine builders (including Shafiroff) will tell you that the 400's dont like RPM, but I believe that its a function of the heads...what can they support flow wise will dictate your cam, and that will dictate your RPM range...Their take is the long stroke doesnt like it (high RPM) but heck lots of BBC guys , including me when I had one think nothing of buzzing 7700-8000 with a 4.25 stroke..

You might want to talk to Engles Shop down in Pok and get his take..Eric builds alot of 406's and 434's with pretty decent HP...

My new car was set up with 14/32's and a 5.14, the couple of time it did go down the track it went 7700 and was still pulling pretty decent...

SST159 · 10-24-2012, 10:35 PM

Dave Wazz up Ya'll!!!
See I'm practicing so when I come visit I got the lingo.
Thanks for the tid bits of info.
I realize the optimum performance is based on the head/cam combo however what I was looking for a safe range to shift and go through the traps with the new combo. I am sure with the 5.14 gear and 31.5 tire I am running, gonna have to make a gear change. as you know it buzzes now 8100 in the traps. There are formulas for piston speed etc which can get pretty in depth.
I want to stay a bit conservative but dont want to leave too much HP on the table.

nickh · 10-24-2012, 11:38 PM

Or you can run a taller tire to kill some of the gear.....

Bill Baer · 10-25-2012, 11:29 AM

Go to Superflow's web site and look under the fow bench info for"flow bench applications and techniques" which contain the formulas for peak HP &RPM based on cylinder head flow.

astikhossw · 10-26-2012, 11:25 AM

Dyno results should give you what you need.Dyno,Dyno,Dyno

SST159 · 10-26-2012, 11:55 AM

Thank to all for the input.
I do understand all the items that come into play to learn the optimum shift point however what I am really looking for is what can you safely buzz a longer stroke combination like this one without it coming apart. Even if the heads or cam combo do not flow to its optimum HP gains, I am more concerned with Safe RPM ranges.
The flow deal I will have to play with for sure.
Dyno Dyno, you are correct which I should concider that before plopping it in the car.
Thanks.

JR fuel · 10-28-2012, 11:36 AM

I run a 394 small block in my dragster with 18 degree head's and it loves rpm 9200 to 9400 . If I chip it down it's a turd.

SST159 · 10-28-2012, 01:15 PM

Hmmm 9400!
You gotta have some very dependable parts in that puppy!

Charlie Yannetti · 11-26-2012, 05:34 PM

If you don't have dependable parts, stay in the garage.. I hate losing rounds due to clean-ups.. just sayin'...

10-24-2012, 12:20 PM	#1
SST159 Member Join Date: Jul 2005 Posts: 301 Likes: 4 Liked 18 Times in 12 Posts	How High do we Buzz the motor? Interesting question for Y'all! I know there are many factors that go into play of answering this question which is: When putting together an engine combination, how does one figure how high the motor could be and should be reved affectively and safely. Are there any formulas out there which help with baseline shift points and trap RPM based on the engine and its components? I am putting together a SBC 401 CU using good parts, Callies crank, Manley Pro lite rods etc. The stroke will be 3.750 and will be using 6" rods. Thanks. __________________ Drew Wonderly SST 159

10-24-2012, 03:53 PM	#2
Dave Steltz Member Join Date: Nov 2003 Posts: 323 Likes: 0 Liked 0 Times in 0 Posts	Re: How High do we Buzz the motor? Huh ? You use a tach ? Ya'll ? You coming down south with me ?? I'd say for you 9500 is a good starting point...lol... On a more serious note alot of engine builders (including Shafiroff) will tell you that the 400's dont like RPM, but I believe that its a function of the heads...what can they support flow wise will dictate your cam, and that will dictate your RPM range...Their take is the long stroke doesnt like it (high RPM) but heck lots of BBC guys , including me when I had one think nothing of buzzing 7700-8000 with a 4.25 stroke.. You might want to talk to Engles Shop down in Pok and get his take..Eric builds alot of 406's and 434's with pretty decent HP... My new car was set up with 14/32's and a 5.14, the couple of time it did go down the track it went 7700 and was still pulling pretty decent... __________________ Dave Steltz 135G SG/SP/SST BIAECH Racing Team

10-24-2012, 10:35 PM	#3
SST159 Member Join Date: Jul 2005 Posts: 301 Likes: 4 Liked 18 Times in 12 Posts	Re: How High do we Buzz the motor? Dave Wazz up Ya'll!!! See I'm practicing so when I come visit I got the lingo. Thanks for the tid bits of info. I realize the optimum performance is based on the head/cam combo however what I was looking for a safe range to shift and go through the traps with the new combo. I am sure with the 5.14 gear and 31.5 tire I am running, gonna have to make a gear change. as you know it buzzes now 8100 in the traps. There are formulas for piston speed etc which can get pretty in depth. I want to stay a bit conservative but dont want to leave too much HP on the table. __________________ Drew Wonderly SST 159

10-24-2012, 11:38 PM	#4
nickh Senior Member Join Date: Sep 2010 Location: Houston,Texas Posts: 670 Likes: 1,838 Liked 235 Times in 97 Posts	Re: How High do we Buzz the motor? Or you can run a taller tire to kill some of the gear.....

10-25-2012, 11:29 AM	#5
Bill Baer Senior Member Join Date: Jul 2007 Location: Nothern IL Posts: 596 Likes: 1 Liked 1 Time in 1 Post	Re: How High do we Buzz the motor? Go to Superflow's web site and look under the fow bench info for"flow bench applications and techniques" which contain the formulas for peak HP &RPM based on cylinder head flow. __________________ Bill Baer 3391 SC, 339B SC, QR Last edited by Bill Baer; 10-25-2012 at 11:35 AM.

10-26-2012, 11:25 AM	#6
astikhossw Member Join Date: Jul 2008 Location: moreno valley Ca Posts: 264 Likes: 2 Liked 19 Times in 8 Posts	Re: How High do we Buzz the motor? Dyno results should give you what you need.Dyno,Dyno,Dyno

10-26-2012, 11:55 AM	#7
SST159 Member Join Date: Jul 2005 Posts: 301 Likes: 4 Liked 18 Times in 12 Posts	Re: How High do we Buzz the motor? Thank to all for the input. I do understand all the items that come into play to learn the optimum shift point however what I am really looking for is what can you safely buzz a longer stroke combination like this one without it coming apart. Even if the heads or cam combo do not flow to its optimum HP gains, I am more concerned with Safe RPM ranges. The flow deal I will have to play with for sure. Dyno Dyno, you are correct which I should concider that before plopping it in the car. Thanks. __________________ Drew Wonderly SST 159

10-28-2012, 11:36 AM	#8
JR fuel Junior Member Join Date: Mar 2009 Posts: 27 Likes: 0 Liked 0 Times in 0 Posts	Re: How High do we Buzz the motor? I run a 394 small block in my dragster with 18 degree head's and it loves rpm 9200 to 9400 . If I chip it down it's a turd.

10-28-2012, 01:15 PM	#9
SST159 Member Join Date: Jul 2005 Posts: 301 Likes: 4 Liked 18 Times in 12 Posts	Re: How High do we Buzz the motor? Hmmm 9400! You gotta have some very dependable parts in that puppy! __________________ Drew Wonderly SST 159

11-26-2012, 05:34 PM	#10
Charlie Yannetti Senior Member Join Date: Jan 2005 Location: Alpine, NJ Posts: 557 Likes: 178 Liked 179 Times in 77 Posts	Re: How High do we Buzz the motor? If you don't have dependable parts, stay in the garage.. I hate losing rounds due to clean-ups.. just sayin'...