Oceanside

Thanks ZMoney! I might just send you a PM later.....

I'll check out the Speed Hunter's article later.

Ocean

Oceanside

Thanks to VO my posting issue was resolved. Duplicate post removed.

INTIMAZY

iTrader: (15)

That super GT in Norway article just brings up even more questions for me.

Only a 262 cam? Granted that 12.3mm of lift is impressive but these heads must flow tremendously well for such a short duration. These cams sound pretty similar in basic dimensions to a Porsche GT3 camshaft. Well, the older ones anyway. So the magic must be in the heads themselves. I'm guessing our valve angles and ports just don't compare to these Motorsport heads. Which is fairly logical knowing how the entire z33 platform was an extensive exercise in parts sharing from other Nissan commuter cars at a time when most manufacturers had just given up on the 2 seater coupe segment.

INTIMAZY

iTrader: (15)

Just to elaborate further about why I think it's inherently a head design limitation, the cams Sasha used to run 370rwhp were around 300 duration and had 13mm of lift. They were large. Very large. To top it off, Sasha also had a very proper intake setup so there should not have been any restriction above the heads for air.

ZMoneyPIT

iTrader: (1)

High compression + high octane = higher power but more knock. These engines are built for races so they aren't built to last forever. That's the key. Also revving to the moon. With their custom ITB set ups they aren't dropping off at 6700rpms.

Oceanside

Hi all,

So I figured now would be a good time to update you on my research in the VQ35 engine more so in FR spec and get THAT sound with reliability and maybe make some HP.

Since my last post, I have looked a few other engines and started the VERY steep learning curve about engine building. It’s like drinking from a fire hose, but I really love reading about it. It’s one of those times that as much as I want to build something-, but can’t for life reasons. However, this is rarely a bad thing. An engine is very complex and reading loads before turning a wrench will probably save me a least a few blow ups. To get a base of information, I’m staying away from forums and reading books. Most of these books (with chunks legally reprinted online) are looking at American V8s, but a lot of the principles seem to hold up with DOHC engines. I’ll give sources (like I have been doing) as I go along.

Some of the other engines I have been looking at are:
-Chevy DZ302
-destroked Chevy 350 to mimic a DZ302
-Ford 302
-Ford Coyote Motor
-20B and 26B rotary (which scream equally as well!!)

One of the things that I have learned in my research is that there seems to be an agreed figure that will tell you how reliable an engine will be and that is it’s mean piston speed (MPS). “...Mean piston speed has long been used as an indicator of component durability under severe service. It is a good rule for evaluating engine potential,” (source). (source).
-~5500 ft/min- ”...When MPS exceeds 5,500 fpm, inconsistent lubrication causes the piston to scuff and, worst-case scenario, friction-weld itself to the cylinder wall. This typically results in cylinder wall scoring and ultimately engine failure,” (source).
-~5000 ft/min- ”...If top-quality race parts are used, the limiting mean piston speed can be increased to 5,000 ft/min,” (source).
-~4500 ft/min- ”...Accepted mean velocity for most racing pistons is about 4,500 fpm,” (source).
-~3500-4000 ft/min- ”...The generally accepted limit for non-race performance applications is about 3,500 to 4,000 fpm,” (source).

So how do we figure that out?

Mean Piston Speed (ft/min) = (stroke x RPM) ÷ 6 (source)

-Stock VQ35DE @ 6600 RPM (OE Redline)
Mean Piston Speed (ft/min) = (stroke x RPM) ÷ 6
Mean Piston Speed (ft/min) = (3.205” x 6600) ÷ 6
Mean Piston Speed (ft/min) = 3525 ft/min

-Stock VQ35HR @ 7500 RPM (OE Redline)
Mean Piston Speed (ft/min) = (stroke x RPM) ÷ 6
Mean Piston Speed (ft/min) = (3.205” x 7500) ÷ 6
Mean Piston Speed (ft/min) = 4006 ft/min

-FR Spec @ 9500 RPM (series redline)
Mean Piston Speed (ft/min) = (stroke x RPM) ÷ 6
Mean Piston Speed (ft/min) = (3.205” x 9500) ÷ 6
Mean Piston Speed (ft/min) = 5074 ft/min

-Alex Kelsey’s Motor @ 8500 RPM (his redline)
Mean Piston Speed (ft/min) = (stroke x RPM) ÷ 6
Mean Piston Speed (ft/min) = (3.205” x 8500) ÷ 6
Mean Piston Speed (ft/min) = 4540 ft/min

Wow. Those figures are eerily right on the money given the ranges specified earlier. Eerie, but cool!

I won’t put the math up (I made an Excel spreadsheet to figure this all out), but an F1 motor during the last V8 era 2006-2013 was only running ~5200 ft/min and a current NASCAR motor runs ~5100 ft/min.

So coming back to the reliability issue, I think it would make sense to keep the redline to 8500 rpm to keep the MPS around 4500 ft/min.

I’m going to get dinner and do some more writing afterwards.

Ocean

Oceanside

Dinner was great!! Egg roll in a bowl FTW!!

Back to engines…..

So why does Alex’s car sound so good?

As I was finishing up my last post, I had an idea pop into my head about how to maybe figure this out.

A couple of years ago I remember reading this article on a night shift or something, but didn’t remeber everyting about it. Looking back at it, it gave me some ideas on how to go about doing this.

Like you all know the VQ35 is a 90 degree V6. According to the service manual, the firing order is 1-2-3-4-5-6 with all the odd numbered cylinder on the passenger side and the even cylinders on the drivers side, front to back. So this means one bank of cylinders is always firing then the other- back and forth, back and forth. This is in contrast to an American V8 in which sometimes in the firing order there is two cylinders firing sequentially on one side and none on another. Check out this video for more.

Let’s figure out the dominant frequency (or fundamental pitch) of Alex’s V6 at full song. I’m going to quote Eric Tingwall who wrote the article in Car & Driver and just sub in the figures for Alex’s engine (source).

“First, you convert engine rpm to Hertz, the frequency unit, with the following formula: 60 rpm = 1 revolution per second, or 1 Hz. Thus, a V-6 spinning at 8500 rpm can be said to be running at 142 Hz (8500/60 = 142 Hz).

But because a four-stroke engine fires each cylinder only once every two crank revolutions, we’re only worried about half the engine’s cylinders. Multiply our 142 Hz value by three (the number of ignition events per crankshaft revolution for a six-cylinder engine) and you have the 425Hz dominant (fundamental) frequency that defines the six-cylinder’s sound at 8500 rpm. As the engine speed increases, the firing frequency rises proportionally.”

So is there any way to test this? Well in my previous career, I mixed rock shows in areas so I have some ideas. Unfortunately my lab grade test rig is in a flight case on the other side of the city, I used what is around my house. Let’s see what happens. Note: I am NOT an acoustic/NVH engineer. If you are, tell me whether I’m on track or not!

I found a clip in the original Smoking Tire video that captured my ears in which you can clearly hear that sound, at full throttle, at the side of the car, without a lot of other noise. I put my iPhone with a spectrum analyzer (an app which takes a sound and breaks it down into a bar graph (each bar is called a band) to see what frequencies make up that sound) about an inch away from my MacBook Pro speakers (which I turned up). I’m also in a quiet room. This is what I got:



See how there’s that elevated bar on the graph to the left of the 500 mark? That’s the original calculated fundamental frequency from earlier of 425Hz. Cool! “So what about that elevated band on the graph that’s to the left of the 1k mark?” Let’s call it 900Hz. That’s a harmonic- extra sonic information that occurs at 2x, 3x, 4x etc. above AND below the frequency of the fundamental. It’s extra bits that come from a dominant frequency to make up a sonic “fingerprint”. In this case it’s a strong positive 2nd order harmonic.

Okay so let’s compare that to an F1 V12- the top of the heap- the Ferrari 412T2. A couple of sources (here and here) peg the redline of the 412T2 at 17 000 rpm.

Fundamental frequency per cylinder= 17000/60
Fundamental frequency per cylinder= 283Hz

6 cylinders are firing per crank rotation as it’s a flat plane V12
Fundamental frequency per crank rotation= 283Hz * 6
Fundamental frequency per crank rotation= 1700Hz

So what does the highly sophisticated iPhone/MacBook Pro spectrum analyser say? I found a clip of the 412T2 here and repeated the process. I tried to freeze the analyser just before the camera moves over the bridge. Like the math says, there is an elevated band of sound around that 1700Hz mark but also at 900Hz. If you remember, 900Hz is the 2nd order positive harmonic of Alex’s motor.



So what? This means that Alex’s motor and a Ferrari V12 are mathematically and sonically related to one another and that’s why they sound eerily the same, but different.

At this point I'm feeling pretty encouraged to know that one of the best sounding V12s of all time is actually related to a fairly understated V6 from Iwaki, Fukushima, Japan or Decherd, Tennessee .

Ocean

bealljk

iTrader: (13)

I thought we were 60*?

great research & write-up thus far!

Oceanside

Yup. You're right it's 60*.

F1Sounds

You don't need RPMs for an F1 sound the Honda cbx 1000 and Mercedes s600 V12 have both demonstrated that. I can't believe there isn't one shop that can produce an F1 sound out of a vq35 at 6500 RPM

DarkZ03

iTrader: (11)

Not that it can't be done, who's going to pay for such R&D?

F1Sounds

Ideally the shops who have already profited from the VQ35 popularity or maybe a shop can just hire an Organ Builder like the Italians do.

DarkZ03

iTrader: (11)

With a car that old I highly doubt it, if it hasn't been done it won't happen unfortunately. Unless someone with unlimited funds is willing to take on a pet project like that.