Traction control and VLIM

All that has to do with the power train, gearbox, clutch, fuels and lubricants, etc. Generally the mechanical side of Formula One.
User avatar
Zynerji
108
Joined: Wed Jan 27, 2016 3:14 pm

Traction control and VLIM

Post

Since my studies seem to suggest that VLIM enhances a few characteristics of an engines output, I was thinking about the TQ increase with longer runners.

My question is simple. If a VLIM positioning is mapped to RPM to maximize hp/tq, could that processor track wheel speed sensors and modify the runner length to lower TQ and regain traction? Is the variance large enough to matter?

Greg Locock
Greg Locock
225
Joined: Fri Jun 29, 2012 11:48 pm

Re: Traction control and VLIM

Post

VLIM is maybe worth 15% of torque? that is nice to have to help control wheelspin, but I doubt it is enough to kill it. So I'd guess no. Here's one way of thinking about it, the grip of a fully locked tire is X% of peak, so to regain grip you have to reduce the torque by 100-X %, kinda sorta.

Hoffman900
Hoffman900
137
Joined: Sun Oct 13, 2019 2:02 am

Re: Traction control and VLIM

Post

It doesn't work that fast, you need to be able to cut things on a cycle by cycle basis (ie: ignition, fuel, and/or both). The VLIMS could be used to kill torque some at launch, but the start is the fastest sweep rate they'll likely see in a race due to starting from a dead stop. Probably north of 3500 rpm/s once they get moving.

Here is a 1D Sim analysis I did of intake length, it's not 15% for sure. A VLIMS is great for torque shaping though and filling on those troughs in a power curve:
Image

Those troughs are usually wave issues from the intake and exhaust side. Since we're interested in an engine accelerating, filling in those holes means the engine is going to accelerate better through the rpm sweep (and be easier to tune).

Here is a 2L Cosworth BDG built by Steve Jennings (found online):
Image

That power curve isn't that great to me. I'd even take a little away from peak to boost that whole curve above 6500rpm. A VLIMS would help lift that whole thing for sure. A lot of times these older Cosworth engines and the like got away with curves like this because they were installed in lightweight Formula or Sports Racer cars. I bet something like an Escort would be faster to shave off 5-10hp to boost that mid range.

A friend built this and has a VLIMS:
Image
https://hotrodenginetech.com/hardcore-h ... challenge/
Power curve:
Image

Hoffman900
Hoffman900
137
Joined: Sun Oct 13, 2019 2:02 am

Re: Traction control and VLIM

Post

Note:

With that Hemi, the system goes from long to short with rpm. They were short time, but with more development, it would go in and out with rpm, as you can see with the simulated intake graph I shared. It’s not as simple as just shortening things.

CMSMJ1
CMSMJ1
Moderator
Joined: Tue Sep 25, 2007 9:51 am
Location: Chesterfield, United Kingdom

Re: Traction control and VLIM

Post

Took me a while to figure out the acronym. :)

( We are talking variable length inlet manifolds.... right!?)

Would you not consider that the driver reaction would be more natural and faster than any motor control in this area? The inlets might change the torque curve but the driver would surely react to the feelings of the loss of grip faster than the system could?

Would be excellent if there was a legal TC in place as it could reduce that cutting in perhaps.
IMPERATOR REX ANGLORUM

J.A.W.
J.A.W.
109
Joined: Mon Sep 01, 2014 4:10 am
Location: Altair IV.

Re: Traction control and VLIM

Post

Ta for that informative post H-900, funny to see that antique Hemi so equipped.

Here's how the factory engineers at Chrysler explored those issues, back in the day:

https://www.macsmotorcitygarage.com/sec ... induction/


(Honda ran a VLIM system on its F1 car, ~55 years ago*, so maybe they'd have some
data of interest in their technical journal publications? Likewise when MotoGP went 4T,
VLIM was one of the 'palliatives' used to partially tame the double capacity/back torque).

*~20 years earlier, Mercedes-Benz had introduced a VLIM system on its DI V12 aero-engines.
"Well, we knocked the bastard off!"

Ed Hilary on being 1st to top Mt Everest,
(& 1st to do a surface traverse across Antarctica,
in good Kiwi style - riding a Massey Ferguson farm
tractor - with a few extemporised mod's to hack the task).

Hoffman900
Hoffman900
137
Joined: Sun Oct 13, 2019 2:02 am

Re: Traction control and VLIM

Post

J.A.W. wrote:
Mon Jan 10, 2022 12:46 am
Ta for that informative post H-900, funny to see that antique Hemi so equipped.

Here's how the factory engineers at Chrysler explored those issues, back in the day:

https://www.macsmotorcitygarage.com/sec ... induction/


(Honda ran a VLIM system on its F1 car, ~55 years ago*, so maybe they'd have some
data of interest in their technical journal publications? Likewise when MotoGP went 4T,
VLIM was one of the 'palliatives' used to partially tame the double capacity/back torque).

*~20 years earlier, Mercedes-Benz had introduced a VLIM system on its DI V12 aero-engines.
Oh absolutely, it's not a "new" idea by any means (variable length). Tuned lengths have been known before the Ramchargers, but it's a fun story.

Here is how Mazda did it on the 4-rotor R26B (1991)
Image

But certainly predates that by a while.

Here is one of the MotoAmerica / FIM (privateer) Superbike engines for sale. Obviously variable valve timing plays a roll here, but with VIMS, you get power curves like this:
Image

However, this tidbit is incorrect:
Explanations for ram induction theory range from simple to fiendishly complex, so we’ll start with the simple version. In a common four-stroke engine, every time the intake valve slams shut, the air-fuel charge packs up behind it. This occurs because the charge has mass and inertia, and at 6,000 rpm it happens 50 times per second. Each time, a reflecting pressure wave is sent back up the intake passage toward the atmosphere at the speed of sound.
It propagates from the cylinder due to the moving piston. I've seen this "slamming into the back of the valve" thing from Superflow and I think it was shared adnauseam in magazines and accepted as fact, as anyone who bought a flow bench, learned from their manual, and that's where it was.

J.A.W.
J.A.W.
109
Joined: Mon Sep 01, 2014 4:10 am
Location: Altair IV.

Re: Traction control and VLIM

Post

For sure fluid-flows are far more dynamic/complex than that simplistic view,
Vizard even notes the hi-po 4T breathing system as a 5-stroke process,(with overlap as the 5th).

Slightly off-topic, but here below Honda utilizes a wave-vortex propagation design essentially
similar in principle to artificial reef structures designed to produce quality surf-riding waves...

https://global.honda/innovation/technol ... -eSTT.html
"Well, we knocked the bastard off!"

Ed Hilary on being 1st to top Mt Everest,
(& 1st to do a surface traverse across Antarctica,
in good Kiwi style - riding a Massey Ferguson farm
tractor - with a few extemporised mod's to hack the task).

Hoffman900
Hoffman900
137
Joined: Sun Oct 13, 2019 2:02 am

Re: Traction control and VLIM

Post

J.A.W. wrote:
Mon Jan 10, 2022 1:40 am
For sure fluid-flows are far more dynamic/complex than that simplistic view,
Vizard even notes the hi-po 4T breathing system as a 5-stroke process,(with overlap as the 5th).

Slightly off-topic, but here below Honda utilizes a wave-vortex propagation design essentially
similar in principle to artificial reef structures designed to produce quality surf-riding waves...

https://global.honda/innovation/technol ... -eSTT.html
I wouldn't put too much stock in Vizard.

Go on here and there are some great articles on tumble:
https://www.hondarandd.jp/point_search_ ... eField.y=0

My guess with Honda's useage of that is the application requires a low intake. The preferred method is laying back the port. You still have Dean's Vortices to worry about in that set up.

That said, Honda does have an paper, where part of it they looked at tumble with a TJI combustion application, and it did not like it. Looking at the Honda combustion video of their HCCI / TJI F1 combustion, I don't see much in the way that would leave to believe there is a lot of tumble happening there, but I could be very wrong as well.

Tumble does work fantastic for port injected engines (and DI), and we can credit Keith Duckworth for understanding it and weaponizing it. The understanding of it and better application of it is a big part why modern engines are more knock resistant and can run higher static compression ratios than engines in the past.

edit: knock resistant, not sensitive. They're less sensitive. :wink:

J.A.W.
J.A.W.
109
Joined: Mon Sep 01, 2014 4:10 am
Location: Altair IV.

Re: Traction control and VLIM

Post

Actually, Honda may've inadvertently revealed a 'backdoor' F1 'traction control' method,
by coordinating fuelling & gear-shifting protocols, as explained in this article:

https://global.honda/innovation/technol ... ew_p2.html
"Well, we knocked the bastard off!"

Ed Hilary on being 1st to top Mt Everest,
(& 1st to do a surface traverse across Antarctica,
in good Kiwi style - riding a Massey Ferguson farm
tractor - with a few extemporised mod's to hack the task).

Hoffman900
Hoffman900
137
Joined: Sun Oct 13, 2019 2:02 am

Re: Traction control and VLIM

Post

J.A.W. wrote:
Mon Jan 10, 2022 2:02 am
Actually, Honda may've inadvertently revealed a 'backdoor' F1 'traction control' method,
by coordinating fuelling & gear-shifting protocols, as explained in this article:

https://global.honda/innovation/technol ... ew_p2.html
Eh, I mean I could look through any manufacturers catalog and find backdoors. I'm sure they're all doing stuff, but without them getting caught, I'm going to assume if they have anything, it's much more sophisticated.

J.A.W.
J.A.W.
109
Joined: Mon Sep 01, 2014 4:10 am
Location: Altair IV.

Re: Traction control and VLIM

Post

Hoffman900 wrote:
Mon Jan 10, 2022 2:08 am
J.A.W. wrote:
Mon Jan 10, 2022 2:02 am
Actually, Honda may've inadvertently revealed a 'backdoor' F1 'traction control' method,
by coordinating fuelling & gear-shifting protocols, as explained in this article:

https://global.honda/innovation/technol ... ew_p2.html
Eh, I mean I could look through any manufacturers catalog and find backdoors. I'm sure they're all doing stuff, but without them getting caught, I'm going to assume if they have anything, it's much more sophisticated.

Well H-900, if you read the interview, you'll find that the system they use is very sophisticated,
& shows much the same characteristics observable in the F1 Honda during operational modes...


As for Vizard, sure, he's into budget do-overs of old-tech, but his experiential flow testing also
dismisses the 'inlet slams shut' trope.

Duckworth admitted he drew ah, inspiration.. from his experience of working with supercharged
sleeve-valve Bristol aero-engines & their 'tumble' oriented porting, along with Honda's 4V bikes.

The current extremely design constrained, yet patently efficient F1 combustion processes are
'on a whole other level' though, as you correctly point out, of course..
"Well, we knocked the bastard off!"

Ed Hilary on being 1st to top Mt Everest,
(& 1st to do a surface traverse across Antarctica,
in good Kiwi style - riding a Massey Ferguson farm
tractor - with a few extemporised mod's to hack the task).

Hoffman900
Hoffman900
137
Joined: Sun Oct 13, 2019 2:02 am

Re: Traction control and VLIM

Post

The "5th Cycle" was a marketing term coined by Ed Iskendarian "Isky Cams" (he's a 100 years old now). To quote another cam designer, "Ed was once asked what his "5th cycle" cams provide, and he said something like "about $100k a year". He was a master salesman."

Vizard has a process for selecting camshafts that he markets and sells by determining the overlap "needed", and then coming up with a lobe centerline, before anything else. There isn't a single cam designer / grinder who agrees with him and despite a lot of smart people telling him it's the events that matter and overlap is just a function of that, he won't budge. He partly (from what I can see) based this on misreading a pressure graph where it showed cylinder depression is highest at overlap, but it was referenced to the port, not atmosphere (it was even pointed out by the guy who sells the equipment). This also gets into his theories on "low lift flow". I've got nothing against the guy, but he's incorrect on this and has been politely told that.

If air slams into the back of the valve, then you closed the valve too early ;). Done correctly, there is always some amount of reverse flow happening the vicinity of the valve seat. Simulated and measured mass traces make this obvious. The slamming into the back of the valve appears in magazines in the hot rod communities, but it isn't backed up anywhere in real engineering texts.

Here are some old mass trace sims I made (with different valve closing and openings (same cam, just changed centerline):

Intake:
Image
Exhaust:
Image

Duckworth was the first to weaponize it and recognize how important it was.

J.A.W.
J.A.W.
109
Joined: Mon Sep 01, 2014 4:10 am
Location: Altair IV.

Re: Traction control and VLIM

Post

Hoffman900 wrote:
Mon Jan 10, 2022 2:56 am
The "5th Cycle" was a marketing term coined by Ed Iskendarian "Isky Cams" (he's a 100 years old now). To quote another cam designer, "Ed was once asked what his "5th cycle" cams provide, and he said something like "about $100k a year". He was a master salesman."

Vizard has a process for selecting camshafts that he markets and sells by determining the overlap "needed", and then coming up with a lobe centerline, before anything else. There isn't a single cam designer / grinder who agrees with him and despite a lot of smart people telling him it's the events that matter and overlap is just a function of that, he won't budge. He partly (from what I can see) based this on misreading a pressure graph where it showed cylinder depression is highest at overlap, but it was referenced to the exhaust port, not atmosphere. This also gets into his theories on "low lift flow". I've got nothing against the guy, but he's wrong on a lot and has been politely told so.

If air slams into the back of the valve, then you closed the valve too early ;). Done correctly, there is always some amount of reverse flow happening the vicinity of the valve seat. Simulated and measured mass traces make this obvious. The slamming into the back of the valve appears in magazines in the hot rod communities, but it isn't backed up anywhere in real engineering texts.

Here are some old mass trace sims I made (with different valve closing and openings (same cam, just changed centerline):

Intake:
https://live.staticflickr.com/65535/518 ... 2ec1_c.jpg
Exhaust:
https://live.staticflickr.com/65535/518 ... af66_c.jpg

Duckworth was the first to weaponize it and recognize how important it was.
Fair enough, good post H-900..

Curiously enough, I recently re-read an old Norris cam instruction sheet for Norton Commando
going back to the mid `70s, & they also dismissed the advert hype re: measured lift/flow #'s,
but included the science relating to dynamic compression effects vs static & volumetrics...

Of possible interest, as it relates to Duckworth's efforts, here below is a link to a technical
article explaining why M-B engineers adopted the DOHC 4V Cosworth head over their existing
SOHC hemi, then 'tamed' it - by VLIM when dropping the SOHC- for customers who found the
initial iteration 'too sporty', & wanted the 'torquey' feel of the earlier engine at lower rpm...

(The article is in German, but the drawings/charts are also English captioned, so its worth a look).

http://www.pvv.org/~syljua/merc/M104Motor.pdf
"Well, we knocked the bastard off!"

Ed Hilary on being 1st to top Mt Everest,
(& 1st to do a surface traverse across Antarctica,
in good Kiwi style - riding a Massey Ferguson farm
tractor - with a few extemporised mod's to hack the task).

Hoffman900
Hoffman900
137
Joined: Sun Oct 13, 2019 2:02 am

Re: Traction control and VLIM

Post

J.A.W. wrote:
Mon Jan 10, 2022 3:29 am
Hoffman900 wrote:
Mon Jan 10, 2022 2:56 am
The "5th Cycle" was a marketing term coined by Ed Iskendarian "Isky Cams" (he's a 100 years old now). To quote another cam designer, "Ed was once asked what his "5th cycle" cams provide, and he said something like "about $100k a year". He was a master salesman."

Vizard has a process for selecting camshafts that he markets and sells by determining the overlap "needed", and then coming up with a lobe centerline, before anything else. There isn't a single cam designer / grinder who agrees with him and despite a lot of smart people telling him it's the events that matter and overlap is just a function of that, he won't budge. He partly (from what I can see) based this on misreading a pressure graph where it showed cylinder depression is highest at overlap, but it was referenced to the exhaust port, not atmosphere. This also gets into his theories on "low lift flow". I've got nothing against the guy, but he's wrong on a lot and has been politely told so.

If air slams into the back of the valve, then you closed the valve too early ;). Done correctly, there is always some amount of reverse flow happening the vicinity of the valve seat. Simulated and measured mass traces make this obvious. The slamming into the back of the valve appears in magazines in the hot rod communities, but it isn't backed up anywhere in real engineering texts.

Here are some old mass trace sims I made (with different valve closing and openings (same cam, just changed centerline):

Intake:
https://live.staticflickr.com/65535/518 ... 2ec1_c.jpg
Exhaust:
https://live.staticflickr.com/65535/518 ... af66_c.jpg

Duckworth was the first to weaponize it and recognize how important it was.
Fair enough, good post H-900..

Curiously enough, I recently re-read an old Norris cam instruction sheet for Norton Commando
going back to the mid `70s, & they also dismissed the advert hype re: measured lift/flow #'s,
but included the science relating to dynamic compression effects vs static & volumetrics...

Of possible interest, as it relates to Duckworth's efforts, here below is a link to a technical
article explaining why M-B engineers adopted the DOHC 4V Cosworth head over their existing
SOHC hemi, then 'tamed' it - by VLIM when dropping the SOHC- for customers who found the
initial iteration 'too sporty', & wanted the 'torquey' feel of the earlier engine at lower rpm...

(The article is in German, but the drawings/charts are also English captioned, so its worth a look).

http://www.pvv.org/~syljua/merc/M104Motor.pdf
That's cool stuff.

As a friend (who is lurking here) has pointed out to me, most of the vintage Cosworth stuff has the intake and exhausts tuned for peak power. You sometimes see tuners elsewhere, in an effort to broaden power, tune the exhaust for peak torque (and construct it in a way so it doesn't choke the system with increasing rpm) and go for an intake length for peak power. You also sometimes see if VLIM isn't allowed, staggered intake lengths. the "Cadillac" (really a Chevy) Daytona Prototype / IMSA engines come to mind. Same with the old Mclaren big block Chevy Can-Am cars.

4 valves will always make more torque than 2 valve if everything is sized correctly. They had to ban the 4 valve Ford Coyote from the defunct 'Engine Masters Challenge' test when the three entered swept the podium and none of the 2 valve engines were close on torque / power average over a rule set rpm range.

Here is an article on the GM DP / IMSA engines:
https://rameywomer.files.wordpress.com/ ... engine.pdf

and here: https://www.slideshare.net/BrianKurn/15 ... cr-engines
(Shows development of intake lengths)