I see these little hondas revving to 9000 and ferraris revving past 10k.

what determines how much an engine can rev? wouldn't it be fantastic if our Z's could rev to 9000?
That would sound so mean!

 

the valvetrain.

notice how the z stops making power uptop? Its cause of the valvetrain. Its not designed from 7k+. You can get some better springs and components and rev higher. Theres an aussies member that i believe revs to 8k.

But, you also have to think about what 8k does for your tranny, injectors, fuel system and is your intake ready for it?

 

You can rev it to 9k. Just slam it into 2nd at about 120mph.

 

hahaha no he mite take u seriously and be out of a ride for a while

 

If it's revs to 9000, somethings wrong with it.

 

the vq wasnt designed to be a high rev motor, its a torquey motor, most tq efficent motors are not high reving at least in the affordable range. Lol But with the revup i was surprised how muched it reved. Theres really no need to rev when all ur avaiable tq is avaiable before hand lol

 

1. Plenum design. The non-revup-plenum is designed to make peak torque around 4000-5000. The rev-up plenum is designed to make peak torque a little bit higher. Therefore, these designs are worthless at high RPMs such as 9000

2. Valvetrain. If the valves are not light enough, they won't be able to move up and down fast enough to keep up with the engine. Also known as valve float. The Z does not have a lightweight titanium valvetrain, therefore it will get valve float around 8000+ rpm



3. Internals and balancing. If the crankshaft is only balanced up to 7000rpm, then going much past that can introduce harmonic vibrations into the system (bad). If the internals are not strong enough, you might just rip them to shreds if you rev up too high.

 

what he said more approprietly lol ^^^^^ lol

 

Im learning new stuff everyday... Thanx

 

So if I get a harmonic balancer and stronger internals, titanium valves, and stronger valve springs, theoretically I should be able to go close to 9k rpms. Right.

 

Theoretically. You also have to look at the stroke. The BMW M5 has a V10 and the stroke is only like 2.6 inches or so, which helps allow it to rev to 8250rpm. Tiny movements allow faster movements.

 

true, didn't think about that.

 

this engine won't be easy to get to rev much past 8000 rpms without major modifications

notice how viper engines only rev to 6000 rpms but have monster power?

 

Right, but you won't be able to use the power unless the plenum and intake runners are designed for 9k rpm. Generally, they should be shorter to make higher rpm peak torque. But plenum volume plays a role too.

 

Like mentioned, valvetrain, bottm end, intake manifold/plenum design but IMO most importantly peak hp. If you build a VQ and do a nice set of cams you may peak at 6700 instead of 6200rpm's, even though you did valvetrain and a bottom end and could theoretically spin the motor to 8000rpm's there would be no point.

 

Yeah, I understand, there's just no engineering past 7000 rpm's, for now at least.

 

Thanks I forgot to mention cam design, but that's important too (even though it's sorta part of the valvetrain). It's impossible to have the best of both worlds. If you want a cam grind to make crazy good torque at 7000rpm it won't make **** at 4000.

 

I wouldn't be worried about how high you can rev, as long as you can make a usable powerband you'll be fine.

 

Toyota's 2zz engine (Lotus Elise <-re-tuned) when the rpm's are above 5800-6k (depending on the year) will kick in a new cam timing which enables them to rev to 8200 stock (2000 model celica gt-s). Some tune them to rev up to 8500-8700 but past that will do more harm than good. I was impress with the design though, the engine seem to be snappy in the mid to upper rpms.

 

Yes you're right, variable cam timing can make a significant difference