Just curious, of the guys rebuilding, what redline are you shooting for and why? I imagine only those doing considerable head work will be shooting for over 7200 rpm.

Thanks,
Jeff

 

I'm bumping the rev limiter up to 7500. Useing JWTs upgraded springs and retainers along with the lightened , forged and balanced bottom end. With the APS TT it should still be produceing good power out past 7200. Basically two reasons for the rev raise , on 91 pump octane it's challenging to obtain > 520rwhp and the cams plus rev upgrade should make it much easier. With the huge kick in first gear it'll be hard to keep from bouncing the oem limiter, so raising adds margin and gives me mor time to shift.

 

Sounds like you'll have a real beast on your hands. Are you using stock valves?

I wonder how far the redline can be pushed without piston speeds going too high or having to use valve springs that can't stay in spec?

--
Jeff

 

I was talking to a local guy here in Charllotte that actually has the first ever 12sec N/A Maximam (2002 model). He ran a 12.8 at 107mph. Same VQ motor as our car. Anyways, he has taken his car up to 7500rpm consistently without the use of valve springs. I think he actually might even have the stock camshaft.

i plan on raising my rev limit to 7100. Intertia loads increase exponentially as RPM's rise. It is NOT a linear increase in load. So going from 6700rpm to 7100rpm is about a 40% increase in intertial load...kinda scary.

 

Yea I gotta a good deal srpings and retainers, so I figured WTHeck. Last thing I wanna do is float a valve and pop a new piston, 7500 is as high as i'm comfortable going, I'm sure rwhp will be dropping by then. anyway.

BTW I stuck with the OEM valves.

 

with springs and retainers, I see no reason why this engine cant rev easliy to 8000rpm. As long as your making power and the turbos can keep pump the PSI at that RPM, that's the foundation of a screamer.

Its interesting to follk the VQ modding inthe Maxima and Altima boards. They are taking their RPM's much higher than most of us in the 350Z world are comfotable doing.

 

My calculations of the mean piston velocities at 8000 RPM on the VQ35DE put the values well below what is found on the Honda F20C (S2000 engine) at 9000 RPM or even several other popular engines (3S-GTE, 2JZ-GTE, Ferrari F355, etc). Our rod/stroke ratio, combined with the stroke length lead to rather low mean piston velocity. If you have cams that can make power up high and rods that can take the load, go for it. I intend to run it out at least to 7500 RPM when I build my motor. I think the key ingredients will be aggressive cams and an aftermarket VTC control solution (whenever such a beast is created).

 

wait a minute, I started a thread a couple months back about what it would take to rev to around 8500 or so and got nothing but people saying it was a stupid idea and wouldn't do any good....

 

You have to dyno it to determine the max flow characteristics of a given head setup.

So it MAY be pointless, if you reach peack WHP at 7100rpm...to rev beyond that. Unless it is done for road racing, or some other purpose.

You never really know until you dyno it with your setup.

 

Is there any other kind of racing?

Seriously, though.. you also have to look at the power band. Reaching peak HP at redline and then cutting it off isn't necessarily the best idea. Even if you drop off above 7100 RPM, you're still likely going to make more power at 7500RPM than at 5750, or whatever RPMS you'll be at after the shift. Ultimately, it just depends on the flow characteristics of your heads/cams and your goals.

 

Yup....for instance...a lot of road race guys like a slightly longer shifting zone...so they dont have to shift mid turn. Or since the 350Z has such short gearing, a high rev limit might help yhour 1/4 mile times if it precludes the need to shift into 5th.