My guess why peak HP is not at redline is because of valve timing and air flow turbulance in the intake manifold and combustion chamber. The engine design and settings like valve lead/lag are probably the reason that hp drops slightly as RPM hits the revlimiter. Just my guess...anyone know for sure?

 

OK - I'm sure I'm going to get some part of this wrong, but here goes. Horsepower is a function of torque and RPM, so the faster you spin an engine at a given torque, the more horsepower. As examples, high-revving motorcycle engines have low torque but high horsepower, while a low-revving diesel has high torque but low horsepower.

Now you're asking, great, but that doesn't answer my question as to why they don't just raise the redline 400 RPM. Well, the answer is that it might not do any good. Remember that it's a "torque curve", meaning that it starts off at a relatively low number, climbs to its peak, and then falls off again. There is a point at which spinning the engine faster doesn't help because horsepower is a function of torque, and if your torque is falling off quickly all you are doing is making more noise and accelerating less quickly.

 

i heard we get a Vtech clone!

 

We already have continuously variable valve timing, which is like Honda's VTEC only over the entire range of RPM instead of just in a band.

 

...no, we have wussy azz VVT, its nothing like Vtech which in effect, uses an entirely different camshaft designed for higher RPMs, different lobes on the same shaft

 

Whatever you say. I have no complaints. From what I understand about it I would much rather have continuously variable valve timing than a 1000-RPM band where variable valve timing is in effect.

If you know something I don't, please clarify with more detail than "wuzzy azz".

 

wussy has 2 s's
*** isnt appropraite for the filter, Vtech is difnt than what we have, if we had Vtech, our cars would cost more and have a better top-end horsepower.

 

Raising the rev limit puts an exponential increase in interial load on the rods, bearings, and crank.

For instance, when RPM is raising from 6000rpm to 7000rpm, inertial loads increase 77%! It's not a straigh line curve, its an exponential increase, and this means less engine life, and greater chances of failure. So it's unlikely that Nissan would go this route, without increasing the strength of the internals. That said, I think 6600rpm was a conservative decision made by NIssan...maybe they'll bump it up a few....we'll see.


PS: about the dyno numbers. We have returned to this particular dyno on several different days, and the stock Z's were turning exactly 224-227hp. The M3 has less quoted drivetrain loss than the Z. That is my point...manufacturers can claim whatever crank HP they want, and nobody is going to test it. Corvettes, Mustangs, Camaros, and M3's tend to post very conservative crank estimates, and hence, they tend to dyno hgher than most on the dyno.

It's inexcusable for Nissan to claim 287 and only dyno 225

 

Uh, 287 is the claimed horsepower at the crank. Dynos, including the one we've been using is at the rear wheels. I'm sure you know that but the way you're posting a claim of 287 and a dyno of 225 is a little misleading.

I forget the drivetrain loss but assuming a 18% drivetrain loss, a stock 6 spd should be about 235 rwhp. And auto would be even less, probably in the 225-230 range. So, a dyno at 225 is not way out of line.

From recollection, downshift believes the claim of 287 is bit high and he's probably right. But, it's not by much. I guess the point I'm try to clearly make is, the comparison should be 235 v 225 rather than 287 v 225 since we need to compare crank v crank or rwhp v rwhp and not crank v rwhp.

Edit: Er, how did I not see mc350z's post? What he said lol.

 

I used to have a 97 prelude VTEC

PLEASE STOP SAYING VTECH guys.

In my personal opionion, while the Z has way more HP (lude had 200HP 164 to FW), there's no comparing VVT and VTEC. cc for cc, VTEC is way more powerful - the switchover to the hot cam is very pronounced and has a great sound to it. The honda motor spin much higher - adding greatly to the vtec benefit.

Granted an NSX motor is handbuilt and all - but still its a 14 yr old motor. Either way, that 3.0L made 280HP. Newer motors S2000 2.0L 240HP, you cant argue with that.

What our motors have which totally has me hooked is the 270lb-ft
of torque.

I cant wait for a modern 3.5L honda VTEC motor!

 

first of all...Vtech is a phone manufacturer, second of all...Honda's VTEC system was made more for gas mileage than power. third, our cars wouldnt cost more if we had vtec, they put vtec systems on the old civic cx's which used to be the cheapest honda you could get.


...i still frequent honda-tech.

 

vtec only SEEMS like its better because you get an instantaneous jump at a certain point from the lower to higher profile cam...in the Z, because it is infinitely variable cam timing, there is no switchover, it constantly optimizes which maximizes HP in every RPM not just low/high...its kinda like the sound of an exhaust makes people think they have more power, well the sudden and noticeable increase from the step point makes you feel that its doing more than something that raises it everywhere...

 

Nissan droped the Liquid Aluminum for 2005 and the new color is Yellow (E33). This one looks really nice!!

 

When comparing Honda vs Nissan engines and boasting about hp/liter because of VTEC note that smaller displacement engines usually yield better hp/liter figures. The old S2000 has only 2 liters and puts out 240hp (over 100 hp/liter) which is great, but so what? Is it that much more efficient then the VQ motor in the Z? Not to mention the torque is anemic in the S. Even with VTEC you can't just bump the displacement of the engine and get the same hp/liter figures. The bigger you go the harder it is to raise that hp/liter (This is for full productions cars of course! Porsches 3.6 liters make a lot more power stock then the VQ engine (but not as much torque? and the GT3 make seven more! ). They did that in the new S2000 and hp stayed the same and had to lower the revs just to gain some more torque. I think the closest VTEC engine to compare against the VVT equipped VQ is Acura's 3.2L. The new TL has VTEC and is rated at 270hp but torque is only 238. Against the 3.5L VQ, it's not that much better hp wise and falls behind in torque. If you bump the displacement to 3.5L it will probably have the same effect as in the S2000. So in my opinion VTEC has nothing on the VQ with VVT

I'm not bashing Honda motors, I had a 1990 CRX SI 1.6L and loved it! (can't wait for honda to bring that car back). They are great and super reliable, we just need to make sure to compare apples to apples.

 

Sorry man, my bad. But we still dont have anything like the Vtec(see, I am getting better)

 

ah ok, that makes sense. so when you examine your hp curve after adding intake mods does the point at which you reach peak hp move to a higher rpm? it should, according to this logic.

 

seriously!!?! where did u find this out and can anyone confirm it?!



EDIT:
also... GUYS GET OFF OF THE VTEC THING!!!!
start a new thread or something. i am in the market
for the 2005 Z and i am very interest in the changes,
not VTEC, Honda, NSX, or any of that. i wanna know
what new changes will be made to my soon to be
baby.

 

DIRN: What is the expected delivery date on an August order for a 2005? I need a Z for Christmas!




Clay