F1technical.net

Hello Guys,


Here' s a video of what appears to be a Renault 65° degree V10, hooked to what appears to be a drivetrain simulator...
https://www.youtube.com/watch?v=5OS_k0V8Bvw


Here is my question, what is causing the shuttering noise that can be heard at 0:08, 0:11 etc ? is it because of flexible engine mounts on the dyno, engine rocks back and forth ? or is it intake tuning that is on the wrong harmonic ???


Also, in the comments there is a guy thats says : "harmonic sound due to 1 piston being offset to add torque"
Was there really a piston that is offset ? What is he explaining ???


Thanks

67 deg
the gas load and the piston mass are asymmetrically distributed in various ways, dependent on rpm
with such shallow pistons there would be some piston rocking and chatter at tdc, dependent on rpm

some rod offset on the piston could help this at some rpm

not rod offset for the traditional reduction of piston side force on power stroke
(doesn't make sense in a 20000 rpm V engine as its gas load doesn't dominate over inertia load and 5 rods would be worse off anyway)

IMO

It looks like the engine was only at 8000 rpm or lower when the engineer shifts up to the next gear.
I would think it's just the engine reacting to the extra fuel and low rpm that made the engine shudder for moment,
I maybe wrong about that, But I know if that was on of my task's at work I'd be smiling from ear to ear

I agree with the remark about transient control at low rpm.

Is this coupled to a resonance/shuffle in the dyno set-up?

The attached is a screen-shot of a tracking FFT of one of the upshifts from the video (8 secs into the video).

The rpm oscillates just after the driver tips back into the throttle?

http://imgur.com/wSwlw9w

I need to get a real life ...

Tommy Cookers, what is gas load balance ? is this firing balance ? is it not well balanced because of the non natural 65° angle instead of 72 ?

Thanks

Brian Coat, Yes it osciliates right after he drops the hammer again

EbuetAmecus wrote:Tommy Cookers, what is gas load balance ? is this firing balance ? is it not well balanced because of the non natural 65° angle instead of 72 ?

Thanks

the H section con rod design was originated (in the Wright Duplex Cyclone aka R-3350) due to the asymmetry of gas load
I believe this means load due to combustion
at c 18000 rpm why would combustion start and remain perfectly centered throughout expansion ?
the rate of travel of the combustion pressure eg laterally, contributing to spreading the pressure evenly across the piston crown ....
is not much faster than the reciprocation
we know that this generation of N/A F1 engines had rather large ratios of rod length to stroke (due to large crankpin dia etc ?)
maybe this helped wrt piston rocking and side force

a straight 5 is rather well balanced so the V angle in a V 10 affects firing intervals but has little effect on balance
(for balance there is no 'magic' V angle for the V10, unlike the 90 deg angle that is compelling in the usual V8 etc)
Renault's 67 deg means only that the firing intervals are slightly uneven, this has a very small effect on the crankshaft design
(in F1 80+ deg, even 90 deg V 10s, having less even firing intervals, crankshaft design was demanding wrt firing order etc)

I could be wrong but I'm not seeing any balance/firing order mystery afoot here.

Just plain old "tip-in torque spike excites k and m (&/or I and alpha) with momentarily wobbly consequences".

@ Brian Coat,

k being the harmonic and alpha the cut off ratio ?

Thanks again,

-Antoine.

i dont care what caused it all that i know is that is porn for the ears : )

EbuetAmecus wrote:Hello Guys,


Here' s a video of what appears to be a Renault 65° degree V10, hooked to what appears to be a drivetrain simulator...
https://www.youtube.com/watch?v=5OS_k0V8Bvw


Here is my question, what is causing the shuttering noise that can be heard at 0:08, 0:11 etc ? is it because of flexible engine mounts on the dyno, engine rocks back and forth ? or is it intake tuning that is on the wrong harmonic ???


Also, in the comments there is a guy thats says : "harmonic sound due to 1 piston being offset to add torque"
Was there really a piston that is offset ? What is he explaining ???


Thanks

That is one badass video.

giantfan10 wrote:i dont care what caused it all that i know is that is porn for the ears : )

I couldn't agree with you more.