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(If you do this, then you have to do that, and if you do that, then you have to do this other thing... LOL)
Good post, Sonic! And that change in timing, is that why tunes for the G/Z typically require bumping up from 91 to 93 octane?
I'm hoping to hear some results this week. Pun intended, having reached out to AT to start the remote tune a couple days ago, and still waiting for response. Very anxious now.
The tuner's job boils down to just one thing:
• Maximize cylinder pressure just after (12-15 degrees of crankshaft rotation) top dead center. This results in more torque, which results in more HP. After all HP = (engine torque x RPM) / 5252.
The limiting factor on ignition timing is engine "knock" or peak cylinder pressure at or before the piston is at the top (aka top dead center). Our engines have 2 knock sensors, once on each bank. They are like a microphone and pick up all engine noise, including engine knock. If the ECU "hears" engine knock via the knock sensors, it will reduce the ignition timing. This decreases power and prevents the pistons from being "hammered" down when they are moving up, approaching top dead center.
As for the bump from 91 to 94 octane, since the tuner wants to give you the most power they can, they like to use 94 octane. More timing advance, without knock, means more power. Everyone is happy!
I look forward to your usual high quality and in-depth review.
Make a tech thread if you need to. There's enough of us that are interested and either somewhat educated on the engineering basics or interested to learn.
I mean, I made a flow bench back when so I could make sure my rotary engine rebuild ports flowed the same... I get it.
Thanks for the idea, I might do that down the road.
Right now I am working with MotorvateDIY for an episode due out next month on how the VQ37 ECU works.
(details on the main processor, how fast is it, which ICs control what and what does the factory code look like)
I suspect once that episode is done, it will get posted on myg37.com in the right section.
With regards to the flow bench... I find it funny, that it really doesn't measure flow.
In theory it measured kg/h (like the motorcycle carb syncro it was derived from) but really we were just looking for even flow (volume) between front and back rotors.
I have been searching the threads but cannot find much to help me. I currently have a 2nd gen g35 with Berk Hfc on it and a topspeed axle back. Sounds great, however, it is raspy. Any recommendations on what to help make the sound deeper and less raspy? I do not care for it to be louder, in fact I would prefer it not to be so loud. Thanks!
I have been searching the threads but cannot find much to help me. I currently have a 2nd gen g35 with Berk Hfc on it and a topspeed axle back. Sounds great, however, it is raspy. Any recommendations on what to help make the sound deeper and less raspy? I do not care for it to be louder, in fact I would prefer it not to be so loud. Thanks!
I have a second gen G35 as well with Berk HFC and a Fast Intentions Exhaust with 18" resonators. Absolutely love the sound, deep and no drone/rasp. If FI is out of your price range, I'd look at getting some larger resonators welded onto your top speed.
Would love to see a clip if you have one! I actually considered this set up, but worried it may be too loud
Seconded! I wanna hear this setup, but to answer your original question: more resonators. I would 100% go with some big 18" ones as mentioned.
I went with the speed culture studios catback, which is just straight pipes but with 3 ginormous resonators doing a ton of work to be the deepest sounding catback out there. I love it.
Interesting, I was actually considering this setup. Do you have Hfc? Also, do you mind uploading a sound clip? Thank you!
Originally Posted by issa9002
Seconded! I wanna hear this setup, but to answer your original question: more resonators. I would 100% go with some big 18" ones as mentioned.
I went with the speed culture studios catback, which is just straight pipes but with 3 ginormous resonators doing a ton of work to be the deepest sounding catback out there. I love it.
Interesting, I was actually considering this setup. Do you have Hfc? Also, do you mind uploading a sound clip? Thank you!
This is the best sound clip I have so far, but I really don't think it does it justice. One of these days I'm going to make my brothers film it on an open road somewhere haha
I had a topspeed axle back before the FI CBE and I have to say, it was way louder. Cold start was definitely something I had to be conscious about but this is perfect if you want something quieter. Loud when you want it, quiet when it should be. Highly recommend, only thing I’d change is maybe go far a FI hfc or RTP because it’s honestly a little too tame..
Here is my Frankenstein exhaust, which contains of:
- 370z Nismo/IPL h-pipe- 370z Nismo/IPL midpipe- Tanabe Medalion axle back https://youtu.be/qbKtToAFSMc
@SonicVQ do you know of any SAE papers or other sciency papers about exhaust sound?
I'm wondering how to apply stuff like the scalloped engine cowlings that newer jets use to reduce noise internally in exhaust flow... that sort of thing. I'm expecting there will be math.
HR/VHR will sound best when both banks are combined (obvious)
With Cat's in the way you'll have to make a decision if HFC or TPs is the route you're going. I suspect this sharp bend after both banks is the first point of resonance that needs to be addressed.
HFC resonated or Resonated pipes with if possible a Helmholtz to a nice flowing 2.5/2.7/3 in pipe will work
Then the longest highflowing inline resonator you can fit between the Y and the muffler will help tremendously
Lastly a decent muffler. Having came from a Tanabe Hyper medallion in older cars I'm a firm believer that a single nice flowing tanabe canister with all of the above will provide a tone enjoyable for older generation folks which will still prove itself.
The H or X pipe between both pipes helps only if you're keeping dual pipes.
I wonder if OEM V8 systems like resonators/chambers/silencers would offer some insight being that the Pushrod v8 suffers from this tromboning at low RPMS as well
Based on this pic it appears that the humongous cats help tremendously with sound + bigger sized resonators + laslty the Tesla mega factory style mufflers. I've seen R/T chargers on muffler deletes and you sure can tell a difference.
05-03-2021, 04:34 PM
