just curious if anyone has found the limits of the stock bottom end rpm wise(n/a).

i know stock valvetrain limit is lower, i'm not a tard. so assume this hypothetical engine has good cams/valvetrain/supporting mods to make spinning it useful.

i see blower/turbo guys are breaking rods so i assume thats the weak link. i would be real curious what broke when the failure happened.

 

I have an 03 non revup, which is 6500rpm redline... Now F/I and revving to 7k no prob

 

we have stout bottom ends,but as you crank up boost cyl pressures will snap your rods like toothpicks,if you want to keep your stock block stop hunting for max rpm.

 

If super/turbo charged engines were to decrease redline by 700 rpm they would enjoy much longer life on stock components.

Not sure if rods or actually rod bolts allow the destruction to begin, guess a slightly bent rod is better than a failed rod going thru the block.

Boost pressure by 30-50% and reduce rpm by 10%

 

The question was asked about n/a not f/i. I want to know this as well. I bought cams valve springs and ti retainers. To fully enjoy the new breathing ability a redline of 7500 will be about right. So with the valve springs in place do I have to worry about the rods failing. For the the f/i people the reason for the rod failing with forced induction is the exact opposite for high rpm. With f/i the rod is most likely failing due to a compression force(usually instigated by a little detonation) with high rpm its a tensile force because the rod can't pull the piston back down due to its velocity. So if its the rod bolts, the rod would separate from the cap. If its the rod it might break at the pin or somewhere else. There is a danger to installing rod bolts on used rods. Its called cap shift, its caused by wear and fatigue on the rod and the holes for the rod bolts not being straight anymore but the old bolts have also moved in the same direction. When you install nice new straight bolts the cap shifts and the bearing is forced out of round and then disaster ensues. If the engine is torn down then you can have the rods resized where the new bolts are torqued in the rods and the big end hole is rebored. This is along the same lines a line boring main caps. Now I have not seen a stock rod apart if there are dowel pins between the cap and rod then cap shift is not a factor and you can just throw the new bolts in. This is where you would want to compare a rev up rod bolt and non rev up rod bolt while you're at it the rods as well. Good luck at this point sometime this winter I am installing those cams/valve springs, rev up oil pump and getting a reflash with 7500 red line and seeing what happens. My thinking is if it doesn't hold I'll get some rod bearing noise and have to build the motor anyway. Although I think the maxima guys have already answered these questions maybe I will have to start lurking around a maxima forum.

 

if the engine is ingesting a larger mix(cams,raising rpm)you will be increasing cyl pressure.depending on valve overlap some press will bleed off, but... rpm increases the strain exponentially.stock rods should not be used in any hp engine that you expect to last.

 

Umm my car was tuned by Jeremy @ Performance Factory...not really concerned about it blowing

 

i am also curious as to what they did to the HR bottom end, correct me if i'm wrong but don't the 07's go to 7500 stock?

as for the cap shift comment, i would be certain that the stock rods are fractured so cap shift would be minimal if you were to slap some rod bolts in there. hell bmw did rod bolts/bearings out the *** with the E46 M3's--i did a few that had over 30k miles and they seem to be holding up fine....now

i have an 06 revup and i can't honestly see another 3-400 rpm being a deal breaker, but i would rather see another 5-800 if i'm gonna spend money on cams/valvetrain/gears.

 

what boost are you running?

 

low 7000's are the practical limit for a non revup motor

 

care to comment on revups?

is there really any difference?

 

my experience is based solely in the earlier motors

yes, there are absolutely differences between the 2

 

http://en.jlu.edu.cn/show.php?id=149

I didn't know what fractured meant I looked it up thats the link. Anywho 7500 with a rev up is normal. Z1 why is low 7000's the limit for non rev ups is it breathing restriction or weak low end? My friend got the notice for his E46 M3 he was less than happy. So is it the rods or rod bolts. I would love to see a rev up rod next to a non rev up.

 

just wait till your friend breaks an exh cam gear--that seems to be the latest snafu with that motor i will never own anything with an S54.

i don't understand the bolded question--are you refering to the fractured part or m3 or what?

 

the rod and rod bolt are the weak link at that rpm, nor was the motor ever deisgned to rev that high in the first place, from the bottom end to the oil pump - the internals differ.

to do those kind of rpms on a non revup, you are looking at a full motor build

 

10psi no problem mon

 

i don't understand the bolded question--are you refering to the fractured part or m3 or what?I was referring to the weak link rods or rod bolts. My friend actually totaled the M3, but he had so many little goofy problems with that car. Z1 I remember somewhere you posted that before you did your build you spun your non revup to 7300 for like two years with no problems, so if I throw in rod bolts, cosworth rod bearings and a rev up oil pump why not 7500. By the way still anxiously awaiting an update on your build. With valve springs the weak link is going to be the actual rod or piston. I am just trying to think outside the box, a full build is crazy for an extra 900rpm. Its not like the engine will be held at rev limiter for an hr or so. But then again with the cams power curve a lot of time will be spent between 6600 and 7300 shifting between 7300 and 7500.

 

you're going to tear your shortblock apart just to swap oil pumps and rod bolts - to gain 200 rpm? Swapping rod bearings while rods are still in the car? That honestly makes no sense. All the while spending all that time and work and still going on stock internals. To each his own I guess, I personally wouldn't recommend it, nor could anyone pay me enough to do it for them

 

back in the day when the reflashes were getting beta tested, Tadashi asked some of his Japanese tuner associates what the ultimate highest RPM is sustainable on stock internals...he found out that the non-rev up's ultimate red line is 7600 sustained and the rods will fail..

so if u keep it below that (7200 etc) then you'll be ok. no real point to keeping it that high unless you have cams or FI.. even then, torque curves tend to drop off after 5500-6000 anyway.

this isn't a honda engine. Vtec doesnt kick in yo after 6k.

 

+1 on Cheston's comments...