6 pack rods, max rpm - Moparts Forums

Register Log In Moparts Forums Unlawfl's Race & Engine Tech 6 pack rods, max rpm

Print Thread

6 pack rods, max rpm #1415701 04/07/13 01:47 AM 04/07/13 01:47 AM
Joined: Oct 2006 Posts: 302 Middle of the US V Verga OP enthusiast
Verga OP enthusiast V Joined: Oct 2006 Posts: 302 Middle of the US	What is the max rpm that 6 pack rods should be turned? EDIT...max safe RPM w/ KB hyper pistons... I know its not 1980, but it is what it is. Motor turns 6500 with ease, just wondering what the safe rpm is for the rods. Last edited by Verga; 04/07/13 11:45 AM. "Im supercharged, might explode in your face"

Re: 6 pack rods, max rpm [Re: Verga] #1415702 04/07/13 01:59 AM 04/07/13 01:59 AM
Joined: Aug 2003 Posts: 43,163 Bend,OR USA C Cab_Burge I Win
Cab_Burge I Win C Joined: Aug 2003 Posts: 43,163 Bend,OR USA	The last 440 bracket motor I used a set in like to be shifted at or under 6000 RPM, it was a TRW 11.5 to one motor with ported 906 heads, solid roller cam and lifters, TM7 inatke and so on. It seem to run into a wall about then. Other similar 440 bracket motors with LY rods would stop pulling hard around 6400 RPM I would take the car to the track and try shifting it at 5000 RPM for two or three runs and then try 5500 RPM and then 6000 RPM, keep raising the shift RPM until the car starts to slow down (look very closely at the 330 and the 660 ET and MPH times ) and then go down 100 RPM at at time until you find the sweet spot Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)

Re: 6 pack rods, max rpm [Re: Verga] #1415703 04/07/13 09:11 AM 04/07/13 09:11 AM
Joined: Jun 2003 Posts: 52,972 Romeo MI MR_P_BODY Master
MR_P_BODY Master Joined: Jun 2003 Posts: 52,972 Romeo MI	Quote: What is the max rpm that 6 pack rods should be turned? Why base your engine rpm on a set of old heavy rods... buy a new set of H-beams and let the dyno tell you what the max rpm will be... I would buy a set of chevy rods to get the small in size and the chevy rods are cheaper the mopar

Re: 6 pack rods, max rpm [Re: Verga] #1415704 04/07/13 10:28 AM 04/07/13 10:28 AM
Joined: Jan 2003 Posts: 9,996 Frostbitefalls MN (Rocky&Bullw... gregsdart master
gregsdart master Joined: Jan 2003 Posts: 9,996 Frostbitefalls MN (Rocky&Bullw...	6200rpm with a stock weight piston, (3.75 stroke) 6800 rpm with the same stroke and a really light stroker piston like in a 451 /400 lowdeck. I built a 440 with them back in 1975, and it is still running today after seeing bracket racing duty in two cars for four seasons. The only reason to use them now days is if they are already rebuilt and you know their history, and it is a budget project that will stay within those rpm ranges. 8..603 156 mph best, 2905 lbs 549, indy 572-13, alky

Re: 6 pack rods, max rpm [Re: MR_P_BODY] #1415705 04/07/13 11:41 AM 04/07/13 11:41 AM
Joined: Oct 2006 Posts: 302 Middle of the US V Verga OP enthusiast
Verga OP enthusiast V Joined: Oct 2006 Posts: 302 Middle of the US	Quote: Quote: What is the max rpm that 6 pack rods should be turned? Why base your engine rpm on a set of old heavy rods... buy a new set of H-beams and let the dyno tell you what the max rpm will be... I would buy a set of chevy rods to get the small in size and the chevy rods are cheaper the mopar Ummmm, cuz they are in the motor and its in the car.........and there isnt a snowballs chance of me takin it back out..... Last edited by Verga; 04/07/13 11:46 AM. "Im supercharged, might explode in your face"

Re: 6 pack rods, max rpm [Re: Verga] #1415706 04/07/13 01:50 PM 04/07/13 01:50 PM
Joined: Jan 2003 Posts: 15,976 Chilliwack B.C. Canada R RUNCHARGER I Live Here
RUNCHARGER I Live Here R Joined: Jan 2003 Posts: 15,976 Chilliwack B.C. Canada	I guess you don't know what it has for rod bolts, I would feel safe running 5500 with the occasional blip to 6k. Those are light pistons though so that will save it. If it had factory weight pistons you'd be on borrowed time. Sheldon

Re: 6 pack rods, max rpm [Re: RUNCHARGER] #1415707 04/07/13 03:37 PM 04/07/13 03:37 PM
Joined: Feb 2003 Posts: 1,099 Massillon, Ohio C cudatom super stock
cudatom super stock C Joined: Feb 2003 Posts: 1,099 Massillon, Ohio	Ran those rods in my cuda from 1988-2000. They were coupled w/heavy TRW 2295 pistons. I shifted at 6500 and went thru the traps at 6800. Used off the shelf ARP rod bolts that were sold at Summit back in 1988. If the cylinder wall hadn't split no telling how much longer I could have ran them. That engine probably had 400-500 passes on it w/o any tear down. Ok

Re: 6 pack rods, max rpm [Re: RUNCHARGER] #1415708 04/07/13 06:23 PM 04/07/13 06:23 PM
Joined: Oct 2006 Posts: 302 Middle of the US V Verga OP enthusiast
Verga OP enthusiast V Joined: Oct 2006 Posts: 302 Middle of the US	Quote: I guess you don't know what it has for rod bolts, I would feel safe running 5500 with the occasional blip to 6k. Those are light pistons though so that will save it. If it had factory weight pistons you'd be on borrowed time. Sheldon MP rod bolts. "Im supercharged, might explode in your face"

Re: 6 pack rods, max rpm [Re: cudatom] #1415709 04/07/13 06:25 PM 04/07/13 06:25 PM
Joined: Oct 2006 Posts: 302 Middle of the US V Verga OP enthusiast
Verga OP enthusiast V Joined: Oct 2006 Posts: 302 Middle of the US	Quote: Ran those rods in my cuda from 1988-2000. They were coupled w/heavy TRW 2295 pistons. I shifted at 6500 and went thru the traps at 6800. Used off the shelf ARP rod bolts that were sold at Summit back in 1988. If the cylinder wall hadn't split no telling how much longer I could have ran them. That engine probably had 400-500 passes on it w/o any tear down. Good info. Just a guess at this point, but Id think if I shift it at 6200 it will go through the lights at 6200-6300, maybe a hair higher. "Im supercharged, might explode in your face"

Re: 6 pack rods, max rpm [Re: cudatom] #1415710 04/07/13 06:39 PM 04/07/13 06:39 PM
Joined: Nov 2009 Posts: 3,410 Belpre,Ohio C CHAPPER master
CHAPPER master C Joined: Nov 2009 Posts: 3,410 Belpre,Ohio	Quote: Ran those rods in my cuda from 1988-2000. They were coupled w/heavy TRW 2295 pistons. I shifted at 6500 and went thru the traps at 6800. Used off the shelf ARP rod bolts that were sold at Summit back in 1988. If the cylinder wall hadn't split no telling how much longer I could have ran them. That engine probably had 400-500 passes on it w/o any tear down. Same situation with my old '80s setup. I still have the motor setting here in the corner. No split cylinder though. Last pass it made before taking it out of car was 6.65 @102 in a 3030# B body. Shifted at 6500 went through the 1/8 at about the same rpm...5.13:1 gear. If you like drag racing, support your local track.

Re: 6 pack rods, max rpm [Re: CHAPPER] #1415711 04/08/13 11:20 PM 04/08/13 11:20 PM
Joined: Feb 2003 Posts: 1,099 Massillon, Ohio C cudatom super stock
cudatom super stock C Joined: Feb 2003 Posts: 1,099 Massillon, Ohio	Yeah best for me w/the combo(DC .590 cam)was 10.82. Car w/me was 3400lbs. Rods never failed. Had the car painted and the body shop moved the 1/2 aluminum fuel line a bit to do the engine compartment. Car was running slower than usual after getting it back. Everything seemed right good oil pressure, fuel pressure was up when bang, split cylinder and then hydro locked the engine. Took a large chunk out of the brock and turned 3 rods into pretzels. After I tore everything down and went to put braided line in I found the kinked fuel line. Car ran lean and that was it. That combo was deadly consistent. Never varied by more than .002-.003 regardless of temp. Ok

Re: 6 pack rods, max rpm [Re: cudatom] #1415712 04/08/13 11:56 PM 04/08/13 11:56 PM
Joined: Oct 2008 Posts: 1,176 East Coast A A/MP super stock
A/MP super stock A Joined: Oct 2008 Posts: 1,176 East Coast	The most important factor of any stressed part, factory or aftermarket, is HOW MANY STRESS CYCLES THE PART IS SUBJECTED TO".If you take a 40 year old factory rod that never sees more than 4000 rpms, say a 440 from a C body, that rod has never been stressed, providing it was well tuned and properly maintained. A HP factory rod has probably seen too many banzai runs and now you are using it in a racing situation. It is only a matter of time and luck before a failure.

Re: 6 pack rods, max rpm [Re: A/MP] #1415713 04/09/13 02:34 PM 04/09/13 02:34 PM
Joined: Jan 2004 Posts: 903 Saskatchewan, Canada cudabin super stock
cudabin super stock Joined: Jan 2004 Posts: 903 Saskatchewan, Canada	I am re-using my original six pack rods on my new build, but I had them magnaflux/crack checked, then installed ARP 2000 rod bolts, and had them resized on the bottom end. With the old heavy TRW six pack pistons, I used to shift at 6,500 all the time and had no issues. This time I am using custom Diamond pistons and tool steel pins that weigh 379 grams less each... I will sleep soundly knowing that the new Mr Six Pack cam likes to be shifted around 6,000 -6,200 rpm and the rev limiter on the new Rev-n-nator box will be set at 6,500 rpm. Lighter pistons, good bolts, and under 6,500 rpm they should be fine! Good luck with it. Arnie 67 Cuda 8.48@ 158.7 mph 1.18 60' 2,600 DA(so far...) 70 Super Bee 440 Six Pack 4-speed. 13.2 @ 104 Stock exhaust/Street tires.

Moderated by Al_Alguire, Hotwheelsjr, moparts, not_a_charger, RangerDan440, tboomer

Hop To

Powered by UBB.threads™ PHP Forum Software 7.7.1