I’m not a scientist and I didn’t stay at a Holiday Inn Express last night. But I’m always up for a good theory, conspiratorial or otherwise. Last night I got hit up on twitter by a guy with an interesting take on the prototype 2018 Corvette ZR1s that have been seen testing recently on the Nurburgring.
Gary Jones, who goes by the twitter handle @mytexel, offers this short bio on his twitter profile regarding his background:
“Worked at NASA a long time; Str. Analysis/Modeling , CAD, IT.. MMS, COBE, Hubble Repair.. At a UM bio tech now..Did a few reviews for Anandtech a long time ago.
Gary tells us that by analyzing the soundtrack from the Corvette ZR1s on the Nurburgring using a spectrum analyzer, he says that the Corvette ZR1’s shift points appear to be at 9000 RPMs:
Humm…. 9000 rpm ..Maybe took the soundtrack from ZR1 at the ring; fed it thru crap spectrum analyzer on my Android phone got this: pic.twitter.com/h154khBSEq— gary jones (@mytexel) May 11, 2017
I replied to Gary requesting some additional info about the accuracy of the smartphone-based analyzer along with determining the frequency of 9000 rpm. His bullet-pointed reply is below:
- 9000 rpm ( rev per min ) = 18000 strokes / min = 300 strokes / sec
- on normal crank get even firing of 2 cylinders simultaneously ( one on each bank ) so 300 bangs out the exhaust per second..
- on flat plane crank it would be half that freq I would think …
- to analyze the sound signature one really needs a good spectrum analyzer … 50Hz to 400 Hz with good resolution .. 9000 rpm = 300 Hz; 6000 rpm = 200 Hz; 3000 rpm = 100 Hz on normal crank
- but lots of associated noise in an internal combustion engine has to be accounted for …
Gary cautions our exuberance saying that for this method to get the most accurate readings, the sound slice would need to be dominated by the exhaust note…not wind tire etc.” and in point #4 above, use a better spectrum analyzer than the “crappy” one he has on his Android phone.
So if Gary’s assumption is correct (You’re not going to argue against science, are you?), the 2018 Corvette ZR1 would have to be powered by the DOHC engine to get those kinds of revs. And speaking of DOHC…
Autoblog had an interesting article regarding the possibility of a DOHC V8 returning to the Corvette. They point to Mercury Marine (the engine builder who produced the 1990-1995 LT5 V8s designed by Lotus for the ZR-1) and their 750-hp SB4 automotive crate engine that was shown at the 2016 SEMA Show. Based on GM’s 7.0L LS7, the motor features Mercury Marine’s own 32-valve DOHC unit which gives the engine an 8000 rpm redline and yet is more compact than an LS3 engine.
The US Navy utilizes spectrum analysis to determine the identity of enemy ships and submarines based on their acoustic signatures. We think this is an interesting way to apply that same technique to determine which engine is in the Corvette ZR1. What do you think of Gary’s technique? Can we get a peer review? Let us know!
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