What helps RPM's? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

ripdog28 · 11-30-2009, 09:26 PM

I am looking at changing my valve springs,cam in hopes of getting a 7-7500 rpm reliable engine. Do i need a lighter Crank,rods,piston or is it mainly the cam and springs. I do know all help but can you pick up more RPM's from cam and springs or by the balancing?

DieselEater · 11-30-2009, 10:18 PM

Bottom end in your sig should be fine upwards of 8K RPM. I would recommend Isky red zones with a solid roller cam, and aluminum roller rockers. Of course you need high flowing heads to hit 8K.

Gearing will get you there also, but may slow you down at the same time...LOL

Check out this site for BBC advice!

http://www.chevelles.com/forums/forumdisplay.php?f=13

A.........

Marv D · 12-01-2009, 08:57 PM

462" takes a lot of piston swinging around, and a lot of stroke. It's the crank forcing all that heavy weight to change directions that typically rips a rod cap off or piston pins out of a piston. I'd be cautious on the top end when you snap the throttle closed.

Myself I'm not a fan of the KB piston line. Do you know what they weigh? As a comparison a typical JE BBC 460 flat top is in the 550 - 590gram range. Whatever you do, when freshening the motor take special note of the piston pin bores.

Super73 · 12-01-2009, 09:48 PM

Quote:

Originally Posted by DieselEater

Gearing will get you there also, but may slow you down at the same time...LOL

Gearing will not "change" operating RPM of a motor.

Operating RPM is typically a function of cam timing. There are other things that can hold RPM back like intake manifolds and headers that are not appropriate for a given combo. But in all reality it is a combo, and needs to be thought of that way.

Generally speaking and cam with a later intake valve closing point and more overlap will spin more rpm.

To Marv's point, piston speed can wear on bottom end parts very quickly. The heavier the components the lower you want to keep piston speed.

Wild83C10 · 12-02-2009, 08:18 PM

Quote:

Originally Posted by DieselEater

Bottom end in your sig should be fine upwards of 8K RPM. I would recommend Isky red zones with a solid roller cam, and aluminum roller rockers. Of course you need high flowing heads to hit 8K.

Gearing will get you there also, but may slow you down at the same time...LOL

Check out this site for BBC advice!

http://www.chevelles.com/forums/forumdisplay.php?f=13

A.........

How did you figure gearing will help with RPM?????

Wild83C10 · 12-02-2009, 08:19 PM

Quote:

Originally Posted by ripdog28

I am looking at changing my valve springs,cam in hopes of getting a 7-7500 rpm reliable engine. Do i need a lighter Crank,rods,piston or is it mainly the cam and springs. I do know all help but can you pick up more RPM's from cam and springs or by the balancing?

Why do you want to rev the motor to 7-7.5k rpms? What are you looking to do?

ripdog28 · 12-02-2009, 08:32 PM

I would like a 7-7,500 rpm limit for when i want to. I would not be at it all the time i just want an engine that can hit it.

cableguy0 · 12-02-2009, 09:07 PM

stuff will live a lot longer at 6500rpm than it will at 7500 especially in a big block. you base your gearing on your engines operating rpm. unless your drag racing only theres no need to spin 7500rpm unless you want to spend a lot of money trying to find a combo that doesnt fly apart and constantly break stuff.

Alex1 · 12-03-2009, 09:30 AM

Quote:

Originally Posted by wild83c10

why do you want to rev the motor to 7-7.5k rpms? What are you looking to do?

x2

DieselEater · 12-09-2009, 07:01 PM

Correct me if I'm wrong.....But...

If you have an engine built to make peak power at 7500RPM, but your gears are in the "high way" range, say under 3.00 : 1...Then why wouldn't you get lower gears to put the engine into its power band?

A........

ripdog28 · 12-09-2009, 09:01 PM

I have 3.70:1 rear gears. I will be able to hit 6500 easy just would like to go a bit higher when i want. The rpm power is very nice i was just looking at how i could add a few revs.

Wild83C10 · 12-09-2009, 09:59 PM

Quote:

Originally Posted by DieselEater

Correct me if I'm wrong.....But...

If you have an engine built to make peak power at 7500RPM, but your gears are in the "high way" range, say under 3.00 : 1...Then why wouldn't you get lower gears to put the engine into its power band?

A........

Wrong.

You select the gearing based on what your power band is, transmission, tire size you have and what your goals are.

If I want an 1/8 mile car/truck and the power band is 4500 to 7k rpms then I could go with a really steep gear 5.XX:1. When I am going through the traps I want my engine to be at 7k+ rpms. Now if I want a 1/4 mile car/truck with the same engine/transmission/tire then I certainly can't run the same gear. I would need a lower gear. Either way the gear isn't going to affect what my power band is or how high my engine revs.

Super73 · 12-09-2009, 11:25 PM

Diesel,

The premise of changing the gear based on the racing your are doing, is correct. IE the example above 1/8 might need a 5.30 gear. Same car 1/4 might need a 4.11. Same car, standing mile, you might need a 3.42 in that car.

The idea of tailoring your gear ratio to the style racing you are doing is correct. But, if a motor can only spin say 6k rpm, going from a 2.xx gear to a 4.xx gear, your motor is still only going to spin to 6k rpm..

DieselEater · 12-10-2009, 10:32 PM

Super73....

That was a great explanation of what you are all trying to say!

Things are a bit different with a sled hooked to you...LOL I understand exactly what you guys meant.

A.........

bigboybodry · 12-11-2009, 10:19 AM

JUST GRAB THE SECOND STAGE AND YOU WILL SEE AL THE RPM'S U WANT

GREAT INFO GUYS THIS IS THE MOST HELPFUL PEOPLE IN THE INTERNET WORLD. KEEP UP THE GOOD WORK.

ripdog28 · 12-11-2009, 11:14 AM

I think ill stick with a 200 shot for a while. Never had juice and dont want to run wild with 2 stages right off the bat.. HAHA. Great looking set up you have there Bigboy.

BossHogg69 · 12-11-2009, 01:36 PM

Quote:

Originally Posted by bigboybodry

just grab the second stage and you will see al the rpm's u want

Great info guys this is the most helpful people in the internet world. Keep up the good work.

dayum!!!!

bigboybodry · 12-11-2009, 02:05 PM

Quote:

Originally Posted by ripdog28

I think ill stick with a 200 shot for a while. Never had juice and dont want to run wild with 2 stages right off the bat.. HAHA. Great looking set up you have there Bigboy.

my old combo was a 468 bbc iron headed 781 with port work,stock crank h beam rods, je pistons flat tap cam and i run 7000 rpm all day long. th400 3.73 gear 29.5/10.5/15 slick or street tires were 295/65r15 m/t et street.i forgot the 200 hp nos plate kit.that is what the shift light was set on. i ran the engine for 6 years and the only reason it broke was due to a faulty nos button (stuck) and before i got it shut down i got a piston. great combo i'll send you the cam specs. if you want.

bigboybodry · 12-14-2009, 09:55 AM

Pm sent i hope that will help.

11-30-2009, 09:26 PM	#1
ripdog28 Registered User Join Date: Apr 2008 Location: Imperial Beach, CA Posts: 1,040	What helps RPM's? I am looking at changing my valve springs,cam in hopes of getting a 7-7500 rpm reliable engine. Do i need a lighter Crank,rods,piston or is it mainly the cam and springs. I do know all help but can you pick up more RPM's from cam and springs or by the balancing? __________________ 69 c-10 BBC 462ci, forged crank, H-beam rods, 10.5-1 KB forged pistons, Dart Iron Eagle 308cc, Straub Cam, Comp Cams chrome moly full rollers, Weiand Team G, Prosystems 950, TH400/3500 Dalenzie stall, Currie 9+ Detroit Locker w/31spline axles.3.5/6in drop. My Build.

11-30-2009, 10:18 PM	#2
DieselEater Registered User Join Date: Dec 2006 Location: Trinidad, Colorado Posts: 642	Re: What helps RPM's? Bottom end in your sig should be fine upwards of 8K RPM. I would recommend Isky red zones with a solid roller cam, and aluminum roller rockers. Of course you need high flowing heads to hit 8K. Gearing will get you there also, but may slow you down at the same time...LOL Check out this site for BBC advice! http://www.chevelles.com/forums/forumdisplay.php?f=13 A......... __________________ 69' 3/4 4X4 470ci BBC 700 HP.... D60/14bolt 205/465 http://profile.myspace.com/index.cfm...ndid=127691959

12-01-2009, 08:57 PM	#3
Marv D Registered Truck Offender Join Date: May 2008 Location: hells training ground (aka Ariz) Posts: 3,118	Re: What helps RPM's? 462" takes a lot of piston swinging around, and a lot of stroke. It's the crank forcing all that heavy weight to change directions that typically rips a rod cap off or piston pins out of a piston. I'd be cautious on the top end when you snap the throttle closed. Myself I'm not a fan of the KB piston line. Do you know what they weigh? As a comparison a typical JE BBC 460 flat top is in the 550 - 590gram range. Whatever you do, when freshening the motor take special note of the piston pin bores. __________________ Still playin with trucks, even at my age! When you're dead, it's only a problem for the people around you, because you don't know you're dead. .....It's kinda the same when your STUPID. I just did my taxes and reviewed my SS statement. Thanks to the current administration it looks like I will only have to work till noon on the day of my funeral.

12-02-2009, 08:32 PM	#7
ripdog28 Registered User Join Date: Apr 2008 Location: Imperial Beach, CA Posts: 1,040	Re: What helps RPM's? I would like a 7-7,500 rpm limit for when i want to. I would not be at it all the time i just want an engine that can hit it. __________________ 69 c-10 BBC 462ci, forged crank, H-beam rods, 10.5-1 KB forged pistons, Dart Iron Eagle 308cc, Straub Cam, Comp Cams chrome moly full rollers, Weiand Team G, Prosystems 950, TH400/3500 Dalenzie stall, Currie 9+ Detroit Locker w/31spline axles.3.5/6in drop. My Build.

12-02-2009, 09:07 PM	#8
cableguy0 Senior Member Join Date: Apr 2000 Location: Delta,Pa Posts: 14,950	Re: What helps RPM's? stuff will live a lot longer at 6500rpm than it will at 7500 especially in a big block. you base your gearing on your engines operating rpm. unless your drag racing only theres no need to spin 7500rpm unless you want to spend a lot of money trying to find a combo that doesnt fly apart and constantly break stuff. __________________ Owner of North Point Car Care in Dundalk Md. We specialize in custom exhaust on both modern and classic vehicles. We are a full service auto shop from classics to modern vehicles. Feel free to contact me with questions. I will give a 10% discount to any board member.

12-09-2009, 07:01 PM	#10
DieselEater Registered User Join Date: Dec 2006 Location: Trinidad, Colorado Posts: 642	Re: What helps RPM's? Correct me if I'm wrong.....But... If you have an engine built to make peak power at 7500RPM, but your gears are in the "high way" range, say under 3.00 : 1...Then why wouldn't you get lower gears to put the engine into its power band? A........ __________________ 69' 3/4 4X4 470ci BBC 700 HP.... D60/14bolt 205/465 http://profile.myspace.com/index.cfm...ndid=127691959

12-09-2009, 09:01 PM	#11
ripdog28 Registered User Join Date: Apr 2008 Location: Imperial Beach, CA Posts: 1,040	Re: What helps RPM's? I have 3.70:1 rear gears. I will be able to hit 6500 easy just would like to go a bit higher when i want. The rpm power is very nice i was just looking at how i could add a few revs. __________________ 69 c-10 BBC 462ci, forged crank, H-beam rods, 10.5-1 KB forged pistons, Dart Iron Eagle 308cc, Straub Cam, Comp Cams chrome moly full rollers, Weiand Team G, Prosystems 950, TH400/3500 Dalenzie stall, Currie 9+ Detroit Locker w/31spline axles.3.5/6in drop. My Build.

12-09-2009, 11:25 PM	#13
Super73 Registered User Join Date: Nov 2007 Location: Bay Area, Ca Posts: 2,841	Re: What helps RPM's? Diesel, The premise of changing the gear based on the racing your are doing, is correct. IE the example above 1/8 might need a 5.30 gear. Same car 1/4 might need a 4.11. Same car, standing mile, you might need a 3.42 in that car. The idea of tailoring your gear ratio to the style racing you are doing is correct. But, if a motor can only spin say 6k rpm, going from a 2.xx gear to a 4.xx gear, your motor is still only going to spin to 6k rpm.. __________________ ------Motor---------------Bottle 60'---1.53---------------1.41 1/8---6.58 @ 105.92----5.87 @ 118.41 1/4---10.38 @ 126.97----9.24 @ 142.49

12-10-2009, 10:32 PM	#14
DieselEater Registered User Join Date: Dec 2006 Location: Trinidad, Colorado Posts: 642	Re: What helps RPM's? Super73.... That was a great explanation of what you are all trying to say! Things are a bit different with a sled hooked to you...LOL I understand exactly what you guys meant. A......... __________________ 69' 3/4 4X4 470ci BBC 700 HP.... D60/14bolt 205/465 http://profile.myspace.com/index.cfm...ndid=127691959

12-11-2009, 10:19 AM	#15
bigboybodry Registered User Join Date: Jul 2009 Location: Florence,Mississippi Posts: 301	Re: What helps RPM's? JUST GRAB THE SECOND STAGE AND YOU WILL SEE AL THE RPM'S U WANT GREAT INFO GUYS THIS IS THE MOST HELPFUL PEOPLE IN THE INTERNET WORLD. KEEP UP THE GOOD WORK. Attached Images __________________ first track pass with the new motor on motor http://youtu.be/YgrJaEF_TaQ Last edited by bigboybodry; 12-11-2009 at 10:22 AM. Reason: PIC

12-11-2009, 11:14 AM	#16
ripdog28 Registered User Join Date: Apr 2008 Location: Imperial Beach, CA Posts: 1,040	Re: What helps RPM's? I think ill stick with a 200 shot for a while. Never had juice and dont want to run wild with 2 stages right off the bat.. HAHA. Great looking set up you have there Bigboy. __________________ 69 c-10 BBC 462ci, forged crank, H-beam rods, 10.5-1 KB forged pistons, Dart Iron Eagle 308cc, Straub Cam, Comp Cams chrome moly full rollers, Weiand Team G, Prosystems 950, TH400/3500 Dalenzie stall, Currie 9+ Detroit Locker w/31spline axles.3.5/6in drop. My Build.

12-14-2009, 09:55 AM	#19
bigboybodry Registered User Join Date: Jul 2009 Location: Florence,Mississippi Posts: 301	Re: What helps RPM's? Pm sent i hope that will help. __________________ first track pass with the new motor on motor http://youtu.be/YgrJaEF_TaQ



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