So....if you're reflashed to rev to 7200, does upgrading the connecting rod bolts cure anything or is that just a myth?

 

upgrading rod bolts definitaly help,but the big end should be re-sized after,it is usually reserved for platforms that don't have a choice and there are so many for the vq it's a no brainer....just put a better rod in.btw just swapping rod bolts without machine work can acually CAUSE the motor to fail.

 

Leave it alone put in the cams and 7300rpm redline. The 7600rpm rod failing information I have never seen that before interesting, I remember an article when gm performance did their catalog for the ecotec and at like 260hp on an engine dyno all four rods simultaneously failed. The equations for force of a piston on a rod result in exponential curves so 300rpm under 7600 is a lot of newtons.

 

i don't see your alls big deal with swapping out rod bolts. it is done all the time. i personally have done 10+ rod bolt/bearing replacements on 6cyl engines that rev to 8k. not to mention all the progcharged C5 ZO6's running around with upgraded rod bolts.

i understand if on a 350 you have to pull the motor, but if you only have to take off the pan then why not? rod bolts are cheap and labor is free.

 

it's not technically a big deal to do on any motor in all honesty....but it's downright messy, extremely time consuming, and largely a waste of time considering the rods in these motors are not exactly "stout" (like putting a silk hat on a pig). And doing rod bearings - I don't even see why you would, or how you could...there are many, many different rod bearing combos for these motors, without any rhyme or reason (all dependant on various serial #'s on the crank). It's not a one size fits all affair.

 

the big end is finish honed with cap torqued down,new rod bolts change the relationship between the rod and cap and should be resized with the new bolts.just because you have done it before does not make it right.spouting bad advice like that is going to cost someone not as lucky as you their motor.

 

how often are you going to be driving at sustained redline for hours on end?

no point other than a headache and wasted money.

 

Stock non revup rods are good to 7500+ RPM as long as ARP rod bolts are installed. Proven over on maxima.org.

 

I don't have a ton of money for mods, therefore I am planning on a budget build. I should get the power I need with mild cams, upgraded valve springs, headers, and by reflashing the ecu with the appropriate redline. $150 worth of connecting rod bolts, plus money for oil pan gaskets, seems like cheap insurance.

 

...till you find out how much the labor costs would be What a completely messy, obnoxious job to do

 

LOL, true.

However, working on cars is my hobby. I have A.D.D. and nothing else in this world calms me like tearing things apart and putting them back together. Well, except Lego's.

 

god bless ya man...there is not enough beer you could give me to swap rod bolts

 

do you realize how big of a pain it is to pull off the upper oil pan without pulling the engine?

 

Yes I do. I'm a professional mechanic. I work on aircraft fuel tanks, which requires climbing inside very small spaces to disassemble things while drenched in jet fuel. Also, I've removed and/or rebuilt many engines. This job shouldn't be a problem, especially knowing a few days work saves me a couple hundred dollars. Please, no more whining about how difficult a task it is. I am aware! The headers won't be a picnic either.

Now, back to the discussion...

All of the literature that I've read recommends resizing the large end of the rods whenever changing connecting rod bolts. However, usually it's been during a full-blown refurbishment of the connecting rods that it mentions it. I'm still not 100% convinced that the connecting rods need to be resized. Plus, it would be a lot of work! Here is a commercially available LSx strengthened connecting rod bolt that claim to require no resizing. Link

Also, Chebosto claims that with stock internals, 7600 RPM sustained will cause rod failure. Was this test done with no load on the engine? I'm sure that when I'm drifting, very high stresses are being placed on the reciprocating parts as I reach 6600 RPM. How do you think that these stresses would compare at 7200 RPM?

 

Just wanted to chime in for you research

Looking at some Japanese tuners

Non-revup reflashes are 7200 limits (agressive) 7000 (Tomei, Amuse --- avg)
Revups are limited to 7200 or so by most including Amuse

Power increases didnt look huge but these are also bone stock cars ....gains were the 7ps range up top and some good mid range gains for RevUps

Some of them are advertising HR reflashes as well which is the most interesting news...the new redline is 7700 vs 7500 stock (Amuse ROM)

So they feel 7000 is pretty safe for their ROMs they sell...just a thought

 

Tsquare usually*reflashes revups to 7500rpm I believe.

 

I had my non-rev-up reflashed to 7200 by Technosquare and asked about the safety of thet RPM limit on stock internals. The guy that did my reflash (Yoshi?) told me they tested and had rod bolt failures after 15 min of sustained 7200 RPM running, but nobody does that, so it's fine in real world conditions. The higher you go, the more risk you take; 7200 is pretty safe.

 

Why do you want to rev your engine to 7600 rpm, when peak power is around 6500-6800rpm maximum? Most engines poop out even earlier than that....even with cams.

The redline of your engine, should be dicated not by piston speed, tensile strength of the rods, etc..etc..and the mechanical limit of the engine, but rather....by the shape of the power curve, and your peak power level.

 

because no rev limiter cars sound like this......

http://www.youtube.com/watch?v=qju9iEFqp3Y

 

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