Knock on the VQ37VHR - gear heads step inside
 

Hi guys, first post!

I've been looking at the dyno's available for the 370Z and it looks like we're getting knock right around peak torque. Looks like these high compression motors are tuned right at the limit.

Your thoughts?

That is extremely uncommon on a stock motor! Are you sure you had good gas? If this is really the case and typical exect to see ALOT of blown FI motors.

Why would you see a lot blown motors? If you go FI than your car must be retuned for optimal performance and safety.


To the OP - where are you seeing this knock you claim? Your post is vague....help us out here

Yes your car would be tuned. However, a tune won't change your compression ratio. High Compression and FI don't go together well. If the VQ is seeing knock with no boost it is undoubtably pulling timing and that results in a net power loss. Same will be true with FI only more timing will be pulled.

We all know high compression and FI don't go well together. Even then the CR of the 370 is not much different from my turbo'd 350DE, which held up well at 400whp. Combine that with the much beefier internals of HR engines and you've got one stout motor. In the end it all comes down to the tune with a proper EMS.

I am more curious as to where the OP is making his statement. I highly doubt any automobile manufacturer will tune their car to the brink of destruction. It would have to be a variable on the users end or a factory defect causing this phenomenon.

Bad gas is my bet.

What device were you using to distinguish knock?

..troll?

Let's NOT jump to conclusion. He hasn't been on since his last post. I am curious to know his reply as well.

Definitely not. Maybe you haven't heard of Berk Technology but they make high quality HFC's for the 350Z. I'm assuming this is the same person. He wouldn't make blanket statements...

No a tune won't help the compression ratio go down any but actually compression is great with FI as long as it is safely tuned. You can get a lot more power per pound of pressure with higher compression. Just look at rsx-s boosted usually with 11.5:1 compression ratio and turboed making 500whp and safely tuned. It is ALL in the tune.

The OEM's are sqeezing more and more power & thermal efficiency out of these motors. From the factory many of these cars are actually tuned quite close to the edge considering how detuned OE's used to deliver their cars.

The two dyno's I'm talking about are the only two dyno's I've seen of the 370z. One from Z1, which is a 100% bone stock car, it's showing knock response right around 4250rpm. Second, is GTM's dyno of their test pipes. Their test pipes showed good gains at ~12rwhp, but with looks like knock response @ 5500rpm.

Don't know where the talk of forced induction came in though.... these cars are both NA.

Picture for reference on the Z1 sheet.

http://img.photobucket.com/albums/v1...noBaseline.jpg

I agree. High compression + FI might not always be the best for 93 octane, but it works great in race circumstances.

Anyone have the GTM graph?

Picture for reference on the GTM sheet.

http://i313.photobucket.com/albums/l.../370Z/DYNO.jpg

Z1 states 50 miles on their car when this pull was made. Could be something as simple as bad gas from the dealer just like JoeyD said earlier.

So the dip is supposed to be knock then? Come on guys that could be any number of things (tach signal loose, gummy injectors, etc.). You want to measure knock get the proper equipment on a load bearing dyno at varying engine speeds.

In a knock event where timing is pulled you will see some indication on the A/F curve(abruptness) and it looks pretty smooth on the Z1 graph.

I'm not saying that its not possible I'm just saying that these types of statements can get taken too far on very little evidence.

Side Note: Much respect to Berk for there excellent testpipes on the S2000. :)

GTM graph with knock response. (red lines)
http://i313.photobucket.com/albums/l...70Z/2ndrun.jpg

It's hard to tell without seeing these cars in person. But the AF will not always change when the ECU pulls timing. These motors might just be very sensitive to knock levels. Remember that the ECU is using a narrowband microphone to measure the characteristic sound signature knock gives off, but isn't a direct measurement of knock.

Hi Tomatoevo! Greetings. I guess you guys already know us from the S2000 world. Your S2000's as well is very prone to pinging & knocking even with the stock ECU. I have had nearly stock cars ping away on the dyno with nothing more than intake/header/test pipe/exhaust.

Time will tell if the 370's are as knock sensitive as I think they are.

Hmm, you are going out on a bit of a limb to call that knock so early in the game and without any real data other than a blip in a dyno curve...

Exactly. That's why I'm posing the question here. What does that blip look like to you?

Double Down Motorsports will be back to back dyno testing our 370Z HFC's later this week. We'll get some real answers from DDM pretty soon.

SWEEEET!!!!!!

Before i was set on the 370Z i was going to get a G37 sedan, and the Berk HFC's would have been my first mod.

Assuming everything goes well at the Dyno, when do you expect the 370Z HFC's will be ready to order?

I'm going to say that it might be knock or an oversensitive knock sensor....but who knows...could be many things including very slight loss of traction on the dyno or the "driver" adjusting his right foot. I do have to say it looks an awful lot like timing is being pulled...

Can't argue with that, S2K's tend to lean out with basic modifications on stock tune.

breaks loose in third? huh...?

+1

Need more info.

What does VSA stand for?

^ Its Nissan's term for their traction/stability program.

Vehicle Stability Assist maybe?

And disabling it let the motor work harder?! Interesting.

Not really. If it detects wheel slippage it will cut the throttle. It's just Nissan's nomenclature for "electrical traction control". Goes by the name of DSC, TRC, E-Diff, etc. But it's all the same thing.

Your foot (gas pedal) isn't actually connected to the throttle plate. It's all done by electronics. Hence the term DBW, "drive by wire".

The only way to know for sure would be to conduct more tests...burn whatever gas is in the tank and fill it with 92/93 and try again.

http://www.the370z.com/engine-drivet...s-stopped.html

Take a look at our Dyno Graphs on 93oct... We didnt see any knock whatsoever. I chalk it up to bad gas if anything. Ben is actually running your HFCs and exhaust. I am bone stock and when you look at the graphs they are nearly identical.

[IMG]http://i234.photobucket.com/albums/e...tillendyno.jpg[/IMG]

for the lazy people :D

Nice! I'm totally stoked at how much power these 370's are picking up with just simple exhaust mods.

It's time for us to develop the Berk Technology 370Z exhaust......

Yes, you should do that, how long would you need my car for R&D? :tup:

BTW, are the HFC's back in stock ?

Knock is a tough one to call on a single blip. I ran a knock sensor on my GTS-3 944 turbo. It was tuned with an Electromotive Tec3. I made plots with race gas, 50/50 blends and with 93 octane. You could see blips in all of them.

What you had to do was get an idea of what the fingerprint looked like for knock. There was always some noise. If it went out of that range there was an issue. This all took a lot of time and it wasn't done on one dyno day.

We're building the 370Z HFC's tomorrow. Will be shipping by the end of the week.

If you want to bring your car by for the exhaust R&D that would be awesome. We would need the car for about a week. We'll give you a free set of HFC's or we can give you a free exhaust when the production pieces are available.

Let me know!

Email us or give us a call.
714-546-BERK

:icon18: that's a great deal for whoever can take you up on it...

here's another dyno chart for inspection, for all the knock experts !

at around 4,400, I think I see a BLIP !! perhaps we need another thread for BLIPs ! :eek:

Keep us posted please! I would be interested in a Berk catback.

Are you guys sure this isn't the VVEL system kicking in? On cars like Honda with the Vtec system they have a little switch over that shows up. Just a assumption here.