ISF4life

iTrader: (30)

7200 rpm is fine 7400rpm is pushing a bit far, 8000rpm like novel was a burst

tas02

iTrader: (2)

I figured if I'm going for altered ignition timing & fueling, then why not a few more rpm as well?

The Isf isn't my daily driver, and I have towing ins. & a transit pass (smiley face emoji).

lobuxracer

iTrader: (2)

The question is for how long? Raising redline shortens service life, no ifs, ands or buts about it. Rings wear faster, pistons crack sooner, rod bearings scuff sooner...there's a whole host of things that change as mean piston speeds increase, and worst of all, with the short rods these engines have, the kinematics of the piston's motion get much worse as rpm climbs. We'd be way happier if the rod length to stroke ratio were greater than 2:1, but it's not possible with a V-8 you plan to put under the hood of any small car.

Mean piston speed is a rule of thumb to understand what is happening. At 6800 rpm, life is pretty good from an MPS perspective. At 7400 rpm, you're just shy of 24 m/sec, which is not considered a long lived mean piston speed, even in racing engines. The Integra Type R is the only production engine to have a mean piston speed this high, and it was quite an achievement for Honda. Lexus doesn't do things that way, and a rod failure at only 8k rpm tells me these are some heavy pistons.

MR2QIK

The bore/stroke rod ratios etc are just not designed for high RPM on the 2UR. Just because you raise the limiter by a few hundred, doesn't mean you'll shift at 7200/7400 all the time. If you're restrained & only do it a handful of times a year (like when needed @ the drag strip), I highly doubt you'll noticeably accelerate wear or induce failure in the bottom end. Keep in mind, Toyota don't design things to be at the limit @ factory levels (at least 10% grace). Unlike a 350/370Z engine which basically runs off knock response.

tas02

iTrader: (2)

Was the rod length altered for the Rcf & Gsf version of our motor?

Jwconeil

Let’s bring this back up for chat. Seems most tunes raise the rev limit to 7200 rpm. Have we seen any failures or shortened service life related to that? From the dyno graphs I’ve seen, I’m not sure I perceive the value of raising the rev limit, but I’m open to an education.

Drok149

I’ve been out of the ISF game for a bit but if I recall the rev limiter wasn’t actually raised to 7200. It would just slip from 68-7200 basically. I do miss my ISF though by far the best car I’ve ever owned!

jat0223

iTrader: (1)

The rev limiter was raised. The problem is that the torque converter unlocks at 6800 rpm.

Drok149

yup that’s what it was I knew it was something that basically made it worthless to do.

Jwconeil

I have experienced that. The car felt like it hesitated above 6800 rpm at the track, unless it was just in my mind.