Wy do Hemi's kick the Rods ???

Looks like almost every used Hemi I see for sale has had windows, I even know personally of a team w/ all top of the line parts and keep up w/maintenance and even they have thrown the rods. WHY ?, Is it RPM ?, Too many runs on the rods ? How many is to many ? 20-30-40. 1/8 mile and 1/4 ?. Does one Rod manufacturer get more runs than another ?. If you keep RPM less than 9800 will it make any differance if you spin it to say 10'200. ?. I would like to here from the guys that have been there/Done that and listen to what you have learned or what you would have done differant ? I have run the 481x wedge w/a Screw,Roots, and even Turbo spinning them as high as 9800, Changed my GRP rods every 20 to 30 runs,and even 40 w/upgraded bolts and Rod material. All 1/8 mile and never kicked the rods. So wy do Hemi's seem to throw the rods more so than any other engine ? Thank You . Joe sr.

 

Most guys own a Chevy motor first. Then when you run out of power and see almost every fast guy at the track with a Hemi , you make the switch. And your first mistake is thinking you can tune a Hemi like a Chevy. Boom! Out go the rods!! Or you see how old And primitive the oiling system is and you think to your self I can make that better or like my Chevy and cause yourself lots of grief.
The tuning window of a Chevy is big. A Hemi is tight and narrow. And adding compression makes any small problems you were having much larger. Sometimes buying a proven piece or paying a high dollar tuner the first couple times makes it all worth it. I've blown up 3 hemis. Most of the times were my fault. Each one was no less than $9000

 

Quite a bit of wisdom there. I ran a detuned chevy and could run decent numbers with a fat low rpm tuneup. The BAE seems like its weak unless you get aggressive with it.

 

This is the correct answer, like it or not.

 

I am NOT an expert tuner.....but have had better luck with nitro and a short stroke (3.75) than I had with alky and a 4.500 stroke...so i think the short arm is your friend...
We are running mostly 1/8 mile @ 4.00 give or take a tenth...1/4 mile are 6.00's...so not pushing it as hard as most TAD and TAFC guys...
Started with all new stuff and very disciplined maintenance program...so far 134 runs since the beginning of 2013 with no major engine damage...maybe a couple of pistons each year due to a stuck ring...our max RPM is usually 8300...
Thanks Troy Martin for the advice and coaching!!

 

How many runs do you put on your rods ? And What brand ?

 

That rnr rod looks really impressive. With everything being larger. I thought for sure it would go 30 runs??

 

p/x 8-10 runs mgp rods but have never kicked a rod tuner is main key

 

Been a few years back now but we ran all the IHRA races, every qualifying shot possible and usually went some rounds... In 3-1/2 years we did not break a single rod. One thing we stayed on top of was maintenance and was fortunate enough not to have to push parts beyond their run limits. I never saw Manzos car dumping connecting rods every race??? It takes a complete package - the drivers right foot, tune up, good parts, and 110% maitenance every lap.

 

Rod bearings are key. They tell a good story on tune up. I'm a firm believer of killer oil pump. Titan, Rcd are a must. Oil psi isn't as important as oil volume.

 

On the oil pump - I talked with System One when building my car...decided on wet sump this time because we hafta dump the oil every run...they recommended their 1.800" length gear pump for a Nostalgia Fuel application...they make bigger pumps - 2.100 and 2.300" but Richard said the larger pump would be too much volume and could starve the bearings...he mentioned that there is a BUNCH of oil traveling through the engine at high RPM...one quart in each valve cover....several in the valley...one in the filter...one in the lines to and from the filter....one in the engine oil passages...some oil suspended and in the block returns...etc...

We use 15 quarts...I did have bearing troubles years ago with a KB Olds - using only 10 or 12 quarts and was running out of oil during the run...

 

I am working on an NHRA turbo pro mod team this year Brad 8 hemi We got 40 runs on a set of GRP rods this is a 10,000 rpm 1/4 mile deal One thing that i have learned is 1 run on new rods drop pan re torque and check them after every 4 runs they keep tightening up a little bit until 20 runs or so