BRS0903

Hey guys! A while ago I was reading about an ECU chip that raised the rev limit to something like 7,200 to 7,300 rpms or something like that. Anybody know what ECU this is?

MY350Z.COM

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Technosquare?

http://www.technosquareinc.com

PhoenixINX

What has you wanting to rev so high?

Plans for a plenum? cams? headers?

A stock Z stops making power at 5800 rpm, thus will yield no benefit revving that high.

A modded one however will... Doug's (www.crawfordzcar.com) was making an additional near 40 hp at redline with all his bolt-ons... Makes good reason to rev then!

Xeinth

Of course there is a benefit of reving of 5800... gearing. You lose a lot of torque at the wheels when you shift, and that is what pushes you.

X

350zdanny

You still have to take the powerband into account I would think, right?

Dan

Xeinth

Yes, your absolutely right. In fact, I was going to work on a excel spreadsheet that calculated your torque at the wheels for each gear based on a dynojet dyno file. That way you could see for your torque curve when the ideal shift point is. I also need to set it up so it takes into account dwnshifts final drive gear change.

All of that effects the ideal shift point, as does how quickly you can shift. (i.e. if you shift slow wait longer).

VandyZ hooked me up with some baseline runs they did at crawford, so Im going to use those to get started.

X

PhoenixINX

You realize our sweetspot is about 4k right?

Revving to redline in a stock Z then shifting will put you past your high torque area.

Shifting around 5500-6000 would keep you well.

daking350

Yuo must also take into account that the stock BEARINGS and RODS were never designed to be revved(is that spelled right )that high in the first place..Unless you build the motor to do this you are eventually gonna run into problems..

PhoenixINX

7k is safe.

7200 is pushing it.

Point well made daking... if you're going to revving past 7k for any duration... check into rods and rod bolts.

Xeinth

Phoenix,

I realize that the engine creates the most power at 4k, but keep in mind when you shift you LOSE torque to the wheels. Thus, the question is do you lose more torque from the higher gear than the torque fall off as you aproach redline? That calculation must be made to determine the ideal shift point.

Torque at the crank is not torque at the wheels.

X

92hatchattack

i thought it has been discused that pretty much the best shift point is at redline .... our peak torque to the wheel is at about 4700 rpms i think ... and if im correct, after a redline shift out rpms drop to about 4800-4900 ----- can anyone confirm this???

and as far as reving high ... once again darking is right .... when a rod is not made for high revs, at higher revs the rod may have a tendancy to actualy stretch .... this couls be a ver bad think ..... i have also heard things about valve keepers poping in the vq35 after about 7300

350zdanny

Yea peak torque is around 4700-4800 rpm and shifting at redline does drop you to 4800-4900 if you shift right, but you have to take into account the fact that it might not be idea, and in fact, is not ideal to shift right to the power peak because of the way our torque band in shaped.

Xenith obviously knows more about the calculations than I do, so I'll leave him to conclude whether or not the idea shift point is redline. I have heard people say 5800-6000 before, but I wouldn't know how to confirm it.

Dan

PhoenixINX

Without breaking out a calculator and excel to build a data sheet...

I'll tell you real world... stock Z vs. stock Z -

One shifted at redline, and the other shifted around 5500ish...

Neither pull on each other.

92hatchattack

hmmmm thats strange..... ive heard people have experimented with shift points at the track and netter their best times when shifting at redline ...... 6000 rmp got them there about 2/10'th slower .... not a huge diffrence ..... but still something

now add a nice plenum and the storry changes

Xeinth

I'll have something in a week or two people can use to calculate their ideal points from a dyno. Im busy now but it shouldnt be too hard.

X

MY350Z.COM

iTrader: (2)

NISMO makes high strength rod bolts.

Jun

iTrader: (45)

I was watching the Best Motoring Video with the Z and i noticed they were switching at 7000RPM...I believe these cars were stock too.

So do the JDM models have a 7K shiftpoint or am i mistaken?

D'oh

I've already calculated this.

Shift @ redline on 1-2 and 2-3.

With the rest, you start dropping the shift point because the gearing won't drop the revs as much. I forget exactly how much, but maybe 200-400 RPM per gear

-D'oh!

D'oh

Well, just for fun, I made a spreadsheet that shows the rear axle torque in each gear. I used the following dyno chart that was posted by Buub a while ago.

I estimate the torque values in 200 RPM increments starting @ 2400 RPM and ending @ 6600.

Based on buub's dyno, it looks like shifting @ redline in practically every gear would be fine (maybe short shift a tiny bit on 5-6). Obviously, a different dyno with a lower top end might show different results. Overall though, it looks like the Z's ratio's are well matched to its powerband.

So first, the dyno I started with:

D'oh

And here is the chart:

-D'oh!