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