maximum rpm on 1UZ?

[JDMfantasy]

I've read that a stock 1UZ can handle up to 9,000 rpm without the limiter, and some cams to make power past 7,000. With a completely built motor (rods, pistons, everything in the head upgraded, cams to make power well in excess of 7k, balanced), what would I be able to wind the motor out to....10..11k..? What the most anyone has ever seen? I've searched around but havent found much....

 

[Pro]

apparently some speedway guys are getting 12,000 rpm out of their stock-but-rebuilt-and-balanced-everything-with-custom-cams engines.

 

[JDMfantasy]

So with all titanium head components I could see more ?

 

[Pro]

dunno man, i still don't believe that 12000 rpm is a useable RPM limit. seems more novelty value to me. but then, these guys have to run NA so maybe...?

i'm no expert on what you'd need to run that kind of RPM. i'm a "turbo_the_std_engine" kinda guy.

 

[chrisman]

i remember reading a post that someone broke a rod at 7800.. i think the rods would have the hardest time-shortest life in a high rpm 1uz.. at high rpms the load on the rod becomes to great--its not necesarily the HP the motor is making--but rpm can definatly shorten the life of a motor..i think with some better valve springs, the heads would have no real problem at 8000+..

 

[JDMfantasy]

Yea I wouldn't think 12,000 would be too realistic either. The extra load by forced induction would also play a limiting factor in such an rpm. The motor will completely built and use two SP68-71 turbos. If we can get a few more thousand rpm to play around with, we may go bigger. Just trying to get a feel for whats been done and what is thought to be safe for a highly forced induction motor.

 

[autronic]

JDMfantasy:

The limiting factor will be the stock crankshaft and the limit will be when it starts to resonate. When that happens it will not take a lot to snap it in 2 or more pieces. If you can controll the harmonics I can see no problem reving it to 10.000 rpm.

Pistons, rods, valve springs, retainers all of these can be made light enough and strong enough to withstand the rpms.

If you add boost the picture becomes a bit more complicated as some parts need to be beefier, especially the pistons.
Heavier pistons means more forces working on the connection rods, the main killer of rods are rpms not boost. The compression forces the rod see under boost is manageble, but the forces the rod see when it tries to jerk a heavy piston down the bore is the one usually killing rods.

 

[BillH2]

One of the biggest limiting factors on RPM is piston weight. Lighter weight=more RPM. Does anyone know what the stroke and the connecting rod center to center length is?

 

[autronic]

BillH2:

The rod centre-centre length is 145.1 mm, the stroke is 82.5 mm.

( Not 162.0 like I first wrote, yes I know me bad... )

 

[BillH2]

So that means the rod length to stroke ratio is 1.96:1. Wow. Definately a candidate for high RPM. The ideal Rod Length to Stroke Ratio is 2:1. Piston speed and side loading is extremely low. The piston spends most of its time at TDC making camshaft timing all the more critical. I would be very careful with head / port and intake modifications. They REALLY did their homework on this one.

 

[MadPhil]

While I sure you can wind the engines out a long way the problem is the camshafts. They are not designed to be used over 8000. I was finding in my race car that the engine was not really pulling past 6800, but it will sit rev higher, just not really produce power. With different cams it is a different story though.
We have one guy in our speedway club that is pulling 9000+ rpm, and I have a set of cams here that are designed to work up until 8500.

I just posted a link the some pics of a rod that snapped in my engine while pulling 7800.
http://www.marxmotorsport.com

 

[Sparky]

Can the stock oil pump handle that high of rpms.

 

[motoflyboy]

Great pics phil, this is definetly a must see for those looking to rev their engines that little bit harder!!

 

[88Alltrac]

Can the stock oil pump handle that high of rpms.

Of course it can!

 

[Cobolt]

Of course it can!

Have you verifyed this by collecting sensor data on varios places on the engine?

 

[88Alltrac]

Just using a simple oil pressure gauge lets you know what pressure at any rpm. Once I hook up the Autronic to this one, I can log oil pressure/rpm for you.

As a side note for revving high,
Knife-edging the crank also helps a lot with reving high and actually frees up quite a bit of power normally lost from the resistance. Also lowers weight of rotating assembly, which should slightly help the engine to rev quicker and easier.

 

[Cobolt]

Yes, but who knows if the varios components of the engine is getting the correct oil flow when running higher RPM:s èven if the standard pump could keep up and hold the oil pressure at the normal level for a standard engine supposed to operate within normal conditions? I mean, it would be good to confirm that what we se at the oil pressure gauge is what we should se for an engine operating outside normal spec.

 

[Sparky]

Some pumps have been known to split at seams at high rpms.

 

[chrisman]

hey sparky-- i have a friend who is like that..gets scared/splits a seam, everytime i take him for a ride..ha,,...

 

[Zuffen]

Forgive my stupidity but why rev it past 7,000?

We know we are reaching into the unexplored and we know they can go BANG at 7,500 so why tempt fate? I love the sound of my engine when it's revved but I use 6,500 as a redline as it really doesn't have the goodies inside it too give me anything (apart for the sound) past my redline. It actually pulls harder in a higher gear at (say) 3,500 than it does at 6,500.

When I build my new engine it will be built to go to 7,000 rpm as it will give me more than enough power at those revs.

I think the concept of who can rev the engine the hardest is like who has the most horsepower. What's the point of 800hp when the engine runs like a hairy goat and doesn't produce usefull power until 4,500 rpm and you need a 5,000rpm stally to get it to move. How much fun will that be on the way to work?

Give me an engine that produces power from 2,000rpm to 6,500rpm and my car will be quicker point to point than the monster that can't be driven at anything less than WOT.

I think we're falling into the "Mines bigger than your's" trap.