Club Cobra Keith Craft Motorsports  

Go Back   Club Cobra > Engine Building, Tuning, and Induction > Small Block Talk

Welcome to Club Cobra!  The World's largest non biased Shelby Cobra related site!

  •  » Representation from nearly all Cobra/Daytona/GT40 manufacturers
  •  » Help from all over the world for your questions
  •  » Build logs for you and all members
  •  » Blogs
  •  » Image Gallery
  •  » Many thousands of members and nearly 1 million posts! 

YES! I want to register an account for free right now!  p.s.: For registered members this ad will NOT show

Keith Craft Racing
Nevada Classics
MMG Superformance
Main Menu
Module Jump:
Nevada Classics
Nevada Classics
Keith Craft Racing
MMG Superformance
Advertise at CC
Banner Ad Rates
Keith Craft Racing
MMG Superformance
Keith Craft Racing
MMG Superformance
April 2021
S M T W T F S
        1 2 3
4 5 6 7 8 9 10
11 12 13 14 15 16 17
18 19 20 21 22 23 24
25 26 27 28 29 30  

Kirkham Motorsports

Like Tree1Likes

Reply
 
LinkBack Thread Tools Rating: Thread Rating: 3 votes, 3.67 average. Display Modes
  #1 (permalink)  
Old 04-19-2011, 08:10 PM
fordracing65's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Dec 2010
Location: Tempe,AZ-Las Vegas,NV-High Point,NC, AZ
Cobra Make, Engine: Kirkham #684, 482FE, Mike Mccluskey build
Posts: 2,482
Send a message via Skype™ to fordracing65
Not Ranked     
Question 427w small block ford rev potential

How high can a 351w bored and stroked to a 427 rev. Im not talking a fully built race motor, but a very built street motor, anyone get them around 7000rpm, saftly. (saftly is the key word).
__________________
PRIDEnJOY
Reply With Quote
Sponsored Links
Sponsored Links
  #2 (permalink)  
Old 04-19-2011, 08:59 PM
Rick Parker's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: May 2001
Location: California, Ca
Cobra Make, Engine: NAF 289 Slabside Early Comp Car with 289 Webers and all the goodies. Cancelling the efforts of several Priuses
Posts: 6,592
Not Ranked     
Default

The piston speed is extreemly high for that combo at that RPM. I think the cast crank would be in dangerous teritory.
__________________
Rick

As you slide down the Banister of Life, may the splinters never be pointing the wrong way
Reply With Quote
  #3 (permalink)  
Old 04-19-2011, 09:43 PM
fordracing65's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Dec 2010
Location: Tempe,AZ-Las Vegas,NV-High Point,NC, AZ
Cobra Make, Engine: Kirkham #684, 482FE, Mike Mccluskey build
Posts: 2,482
Send a message via Skype™ to fordracing65
Not Ranked     
Default

so about 6400rpm then max.
__________________
PRIDEnJOY
Reply With Quote
  #4 (permalink)  
Old 04-20-2011, 02:47 AM
Tony Radford's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Aug 2002
Location: Dacula, (Atlanta), GA
Cobra Make, Engine: Unique 427 SC, Southern Automotive 427W Stroker
Posts: 1,649
Not Ranked     
Default

I was told by the builder that my 427w stroker would hit 7K but that shifts at that rpm were limited. I chicken out at 6,700 - but that's pretty exciting. She's still pulling strong at that rate. You'll probably need a solid cam to get that high.
__________________
After a good hard ride.....oil pressure is over 50, temp is below 190, she idles and no new dents. LIFE IS GOOD!
Reply With Quote
  #5 (permalink)  
Old 04-20-2011, 02:48 AM
undy's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Jul 2005
Location: Virginia Beach, Va & Port Charlotte, Fl.,
Posts: 2,203
Not Ranked     
Default

It depends on how exotic you want to go...

The LS7 (I know it's a chevy) is a 427 small block and it twists 7 grand all day long from the factory, for over 100K miles. Use the same technology and your windsor can do the same. The LS7 uses titanium rods, titanium intake valves, sodium filled exhaust valves, light weight pistons along with a host of other light weight componants. The point is, a 427 Windsor stroker has the "potential" for a reliable 7K+ RPM capability.
__________________
Too many toys?? never!
Reply With Quote
  #6 (permalink)  
Old 04-20-2011, 03:23 AM
CC Member
Visit my Photo Gallery

 
Join Date: Mar 2001
Location: E BRUNSWICK N.J. USA,
Posts: 3,841
Not Ranked     
Default Has the motor been dynoed??

fordracing65 You have a couple of simple questions to answer,
Is the crank crankshaft and rods cast for forged??
What is the max power range of the camshaft? REV range?
Why are you looking for 7,000 rpms?
Are you running an aftermarket block with crankshaft support for caps?
The old rule of thumb is 3-500 rpms pass max hp tops out.
Here's the key question, if you are going to beat on a motor this hard you better know that it is possible for it to break and parts to come visit you in the drivers compartment. Unless you are in a titanium tub like an "A-10" you could get hurt for pushing this motor past a safe red line. What is the matter with a 6,200 rpm limit?? If you are looking to go faster speed, lower the rearend ratio. This will help lower the revs on the motor and extend the life of it. Rick L.
Reply With Quote
  #7 (permalink)  
Old 04-20-2011, 04:38 AM
CC Member
Visit my Photo Gallery

 
Join Date: Dec 2001
Location: Louisville, KY
Cobra Make, Engine: I'm Cobra-less!
Posts: 9,305
Send a message via AIM to blykins
Not Ranked     
Default

Too many variables to answer that question...

For a Dart block with a 4.125" bore and a 4" stroke, good rods and crank, then yes 7000 is no problem whatsoever.

It all depends on a lot of things....
__________________
www.lykinsmotorsports.com
Reply With Quote
  #8 (permalink)  
Old 04-20-2011, 05:36 AM
Seasoned Member
Visit my Photo Gallery

 
Join Date: Apr 1999
Location: Portsmouth, VA
Cobra Make, Engine: Unique 427 S/C, Dart 427W "Replica" Ford engine
Posts: 584
Not Ranked     
Default

...plus the Dart block uses the smaller Cleveland journals/bearings which allows higher rev's and lower temp's. NASCAR does the same thing.
Bill Stradtner
Reply With Quote
  #9 (permalink)  
Old 04-20-2011, 06:48 AM
Jerry Clayton's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Jul 2005
Location: Bartlett, Ill
Cobra Make, Engine: Everett-Morrison LS1
Posts: 2,424
Not Ranked     
Default

The biggest drawback to using the 351w at those speeds are the bearing speeds--with a 3 in main-------
now you can get a Dart with the Cleveland main size or you can build up something with the 289/302 size----
The Dart bigger bore smaller main size with the shorter stroke can be run well past 8500
Reply With Quote
  #10 (permalink)  
Old 04-20-2011, 07:19 AM
CC Member
Visit my Photo Gallery

 
Join Date: Mar 2009
Location: Mendota, IL
Cobra Make, Engine:
Posts: 582
Not Ranked     
Default

Undy I dont think that Ls7 would last even 10k at a constant 7000 rpm and max hp. On the road that motor will not even average 100 hp for 100k miles and at a lot lower rpm. Some times they have a hard time making a stock car engine even last 500 miles Mark

Last edited by MAStuart; 04-20-2011 at 07:23 AM.. Reason: added somthing
Reply With Quote
  #11 (permalink)  
Old 04-20-2011, 07:21 AM
LMH's Avatar
LMH LMH is offline
CC Member
Visit my Photo Gallery

 
Join Date: Apr 2005
Location: Tucson, AZ
Cobra Make, Engine:
Posts: 5,210
Not Ranked     
Default

Just my opinion but I think 6400 would be pretty high for a production block 427W.
Like Jerry says, Dart block with bigger bore and shorter stroke is the way to go.
Probaly have to use solid lifters too for that RPM range.
Larry
__________________
Alba gu bràth
Reply With Quote
  #12 (permalink)  
Old 04-20-2011, 08:45 AM
CC Member
Visit my Photo Gallery

 
Join Date: Feb 2007
Location: Colorado Springs, CO
Cobra Make, Engine: Backdraft, supercharged Coyote
Posts: 2,282
Not Ranked     
Default

With good quality (not exotic unobtanium) forged rotating assembly, a stock block is probably good to about 6,500-7,000, depending on load.

The limiting facter is usually the valve train. If you use the right parts, a hydraulic roller can safely run to about 6,500. Standard parts (like stock lifters and springs) lowers the red line considerably. As said above, the chevy 427 can run to 7,000 by using a lot of expensive and exotic valve train parts.
__________________
.boB "Iron Man"
NASA Rocky Mountain TTU #42
www.RacingtheExocet.com
BDR #1642 - Supercharged Coyote, 6 speed Auto
Reply With Quote
  #13 (permalink)  
Old 04-20-2011, 09:03 AM
CC Member
Visit my Photo Gallery

 
Join Date: Jan 2005
Location: Rancho Cucamonga, ca
Cobra Make, Engine: SPF 239
Posts: 820
Not Ranked     
Default

Properly built (Forged rotating parts, roller and sturdy valve train, good oiling)
Sure it will spin 7K safely.
I think the line between “race motor” and “street motor” gets pretty dam blurry when you talk about that kind of RPM.
But like Rick said “Why?” Is the goal speed or bragging rights?

Jerry, I like your bearing speed comment. Not often addressed.


Jason
Reply With Quote
  #14 (permalink)  
Old 04-20-2011, 09:14 AM
fordracing65's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Dec 2010
Location: Tempe,AZ-Las Vegas,NV-High Point,NC, AZ
Cobra Make, Engine: Kirkham #684, 482FE, Mike Mccluskey build
Posts: 2,482
Send a message via Skype™ to fordracing65
Not Ranked     
Default

I was going to build one and i have a $20000 budget, not so concerned how high it can rev, more concerned how big of a powerband i can have, fuel injection is where most of the budget will go, and i will be using a dart block, i know there are alot of factors, just getting a ballpark idea,
__________________
PRIDEnJOY
Reply With Quote
  #15 (permalink)  
Old 04-20-2011, 09:16 AM
lovehamr's Avatar
Stolen Avitar
Visit my Photo Gallery

 
Join Date: Oct 2004
Location: Brunswick, GA
Cobra Make, Engine: BDR 1311 428PI
Posts: 3,044
Not Ranked     
Default

Several people have asked "why?" and I have to go with the OP on this. I'd like my big inch small block to rev to 7K as well. Why? Because it sounds so cool!!!!
Reply With Quote
  #16 (permalink)  
Old 04-20-2011, 09:31 AM
Ron61's Avatar
Senior Club Cobra Member
Visit my Photo Gallery

 
Join Date: Dec 2001
Location: Shasta Lake, CA
Cobra Make, Engine:
Posts: 26,323
Not Ranked     
Post

When I had my Cobra I had a 351 stroked to 418 and the horsepower topped out at 6200 RPM. I did hit 7,000 a couple of times by accident. Once when I hit a spot of oil and once when the posi unit broke. But that was only for a few seconds. Normally I ran it at around 6,000 RPM.

Ron
__________________
Ron 61
Ronnie Widener


View my Miscellaneous Gallery
Reply With Quote
  #17 (permalink)  
Old 04-20-2011, 09:37 AM
Jerry Clayton's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Jul 2005
Location: Bartlett, Ill
Cobra Make, Engine: Everett-Morrison LS1
Posts: 2,424
Not Ranked     
Default

Jason

Bearing speed, among several other things, are addressed here several times a day(and sometimes nite)
Reply With Quote
  #18 (permalink)  
Old 04-20-2011, 10:53 AM
CC Member
Visit my Photo Gallery

 
Join Date: Jun 2005
Cobra Make, Engine:
Posts: 3,077
Not Ranked     
Default

Valve float would be the limiting factor in my opinion, A poor profile could float as early as 5500 rpm's, or poor springs.
Reply With Quote
  #19 (permalink)  
Old 04-20-2011, 11:06 AM
CC Member
Visit my Photo Gallery

 
Join Date: Oct 2010
Cobra Make, Engine: Superformance
Posts: 663
Not Ranked     
Default

My two cents. Engines sound wonderful above six grand. And many have profiles and a bottom end w/stout drivetrain to survive above that and still generate power up there. But alot of bad $#it can also happen above six grand...it's like climbing Mt. Everest and going above the fourth camp site into the "kill zone." You may summit and come back to brag about it. Then again, you may not. I personally build my motors to survive no higher than 6,500 and if built right they will pull to that all day long and last several cycles.
Reply With Quote
  #20 (permalink)  
Old 04-20-2011, 11:16 AM
CC Member
Visit my Photo Gallery

 
Join Date: Dec 2001
Location: Louisville, KY
Cobra Make, Engine: I'm Cobra-less!
Posts: 9,305
Send a message via AIM to blykins
Not Ranked     
Default

The best advice I can give is build the engine for the purpose. There's no use in having a 7000 rpm engine (with the heads/cam necessary to do so) if you're just going to drive in stop/go parades all day.

Pick a purpose, then build the engine to make the most horsepower in that specified rpm range.
__________________
www.lykinsmotorsports.com
Reply With Quote
Reply

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -7. The time now is 02:08 PM.


Powered by vBulletin® Version 3.8.0
Copyright ©2000 - 2021, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO 3.6.0
The representations expressed are the representations and opinions of the clubcobra.com forum members and do not necessarily reflect the opinions and viewpoints of the site owners, moderators, Shelby American, any other replica manufacturer, Ford Motor Company. This website has been planned and developed by clubcobra.com and its forum members and should not be construed as being endorsed by Ford Motor Company, or Shelby American or any other manufacturer unless expressly noted by that entity. "Cobra" and the Cobra logo are registered trademarks for Ford Motor Co., Inc. clubcobra.com forum members agree not to post any copyrighted material unless the copyrighted material is owned by you. Although we do not and cannot review the messages posted and are not responsible for the content of any of these messages, we reserve the right to delete any message for any reason whatsoever. You remain solely responsible for the content of your messages, and you agree to indemnify and hold us harmless with respect to any claim based upon transmission of your message(s). Thank you for visiting clubcobra.com. For full policy documentation refer to the following link: CC Policy
Links monetized by VigLink