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VTEC CART


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#1 chunder27

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Posted 12 February 2016 - 17:43

Not sure whether this might be better in the nostalgia section, i will let mods decide?

 

Does anyone remember Honda using their VTEC system in a CART engine in the 90's?  I think Rahal maybe used it, I recall it was a disaster really, but would be interested with any links to perhaps mag features of the time and reasons why it maybe was not a good idea?



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#2 Fat Boy

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Posted 12 February 2016 - 20:32

No. That Rahal program was bad, but VTEC was not part of it. Whatever they had going on there, they fixed it in the next couple years. That first year was a disaster, though.



#3 chunder27

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Posted 12 February 2016 - 22:28

I am absolutely positive that Honda somewhere along the line tried the VTEC system in a CART engine when they were involved in CART.

 

Can anyone else remember this?



#4 Magoo

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Posted 13 February 2016 - 22:48

As I see it, CART engines did not use a wide enough power band to make VTEC of any particular benefit. I sure don't remember it. I could be wrong. It's happened. 



#5 chunder27

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Posted 14 February 2016 - 00:07

I am positive it was used in CART, although I do not know what year and by which team, perhaps only a one car entry and all the other teams used a normal V8 turbo.

#perhaps it might have only been used in practice or in testing, I did take far more interest in CART at this time than any other, and I think perhaps we all did at some time, but this for some reason I remember and no-one else does! lol!



#6 MattPete

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Posted 14 February 2016 - 01:57

Honda tried making a big-bang motor (that failed), but I don't remember V-Tec being used.



#7 Chubby_Deuce

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Posted 14 February 2016 - 02:25

#perhaps



#8 chunder27

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Posted 14 February 2016 - 08:36

Helpful as ever you nasty piece of work.

 

It might well have been the big bang motor then 



#9 bigleagueslider

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Posted 16 February 2016 - 02:38

The CART engine regs during that time were fairly restrictive regarding valvetrains. Had to use metal valve springs and variable lift/duration/timing systems were not permitted.



#10 chunder27

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Posted 16 February 2016 - 18:34

I am thinking I might have got wires crossed then and it might be a big or long bang engine configuration with the crank. Pulses close together type thing.

Could you change the firing position on a V8 crank to close the pulses together as Honda did on their NSR500 2 stroke engine in 92?  And also similarly what Yamaha did with their Yamaha engine in bikes for Rossi arriving in 2004?  Would that be legal in CART at the time?

 

I know they did something different, but not sure exactly what!



#11 Patrick Morgan

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Posted 29 February 2016 - 11:42

Variable cam timing was possible on the Ilmor 265C,D 108 and 108C engines, (1993 - 1996) but was generally locked off. My understanding is that it was not of much benefit and addd complexity and the potential for failures. The photo below shows the "knife and fork" that lock the epicyclic carriers that adjust the timing. 

 

12791587004_f1784291a1_k.jpg265D 9th Butterfly by dtperformanceltd, on Flickr



#12 bigleagueslider

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Posted 04 March 2016 - 02:28

Patrick Morgan, those are some great pictures of the Ilmor Indy engines. Are you sure the tab/clevis brackets attached to the drive ends of the intake/exhaust cam shafts are used in place of a variable cam timing mechanism? For an all-out race engine where cost is not a big concern, I would imagine if the variable cam phasing mechanisms were not being used they would be removed and replaced with a more simple/reliable/lightweight arrangement of gears attached directly to the camshafts.

 

Is it possible the components are part of a cam drivetrain torsional vibration dampening system? The torsional vibration environment in a multi-stage spur gear cam drive on a V8 engine with a flat crank can be very difficult to deal with. In the picture you posted, it looks like the idler gears have some sort of tuning mass attached to them.



#13 gruntguru

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Posted 04 March 2016 - 04:39

 

For an all-out race engine where cost is not a big concern, I would imagine if the variable cam phasing mechanisms were not being used they would be removed and replaced with a more simple/reliable/lightweight arrangement of gears attached directly to the camshafts.

That would require a major redesign of the timing geartrain. The cam gear is clearly turning faster than 1/2 engine speed with that epicyclic gearset in there.



#14 bigleagueslider

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Posted 07 March 2016 - 02:06

gg- In the photo provided it appears the epicyclic input member is the ring gear (integral with the driven spur gear), the fixed member is the carrier, and the output member is the sun gear (connected to the camshaft). Wouldn't this arrangement normally result in a speed increase? Did I miss something?



#15 gruntguru

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Posted 07 March 2016 - 03:17

Thanks for pointing that out. You are quite right.



#16 Patrick Morgan

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Posted 08 March 2016 - 16:20

I've added 2 pictures below that should hopefully make it clearer. The knife and fork locks the system off - under variable operation the red disk, which is attached to the sun gear via a polygon drive, is rotated which changes the relationship between the cam and the annulus gear. The planet gears drive the cam, the sun gear remains stationary. Does that make sense?

 

24990035103_f4d273b5a6_h.jpg265D 1 by dtperformanceltd, on Flickr

 

25321142890_187a92f67e_h.jpg265D 2 by dtperformanceltd, on Flickr

 

The system remained until 1996 in the Indy engine (it was also featured in the 2175A F1 engine). 1996 was a tough year by Ilmor's standards with the low point being Al Jr's blow up while leading the last lap at (correct me if I'm wrong) Elkheart Lake. For 1997 there was a drive to eliminate things that might compromise reliability and the cam gears when back to being spur gears.


Edited by Patrick Morgan, 08 March 2016 - 16:23.


#17 bigleagueslider

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Posted 09 March 2016 - 02:07

Patrick Morgan- Thanks for the very nice CATIA V5 images! 

 

The input member is the blue ring gear/cam drive spur gear. The fixed member is the purple sun gear, which is connected to the red hub via a three lobe polygon coupling, and the red hubs are each clamped to the blue clevis/blade arms by 6 fasteners, with slots that allow some timing adjustment. The carrier is the output member. Its green planet gears are mounted on the light blue shafts that are fixed to a flange on the end of the peach-colored cam shaft. Just for fun, when I have time I'll try counting the gear teeth to figure out the epicyclic's ratio.

 

One thing I noted in the CAD model is that the teeth of the two blue spur gears appear to overlap as if they were intended to mesh. Is that the intent, or is it just an optical illusion?



#18 gruntguru

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Posted 09 March 2016 - 04:00

One thing I noted in the CAD model is that the teeth of the two blue spur gears appear to overlap as if they were intended to mesh. Is that the intent, or is it just an optical illusion?

 

That would be a big problem since they rotate in the same direction!



#19 Patrick Morgan

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Posted 09 March 2016 - 10:17

Don't get too hung up on the gear tooth numbers - this was a model I created to illustrate Jade Gurss book "Beast". It's very close to the original all respects but the tooth numbers might not be accurate. I spent 3 months on the models and diagrams and was paid in Lego so there were a few things I had to cut corners on, I didn't for example measure the polygon with anything more than a vernier caliper. I did the exploded view for you guys at lunchtime yesterday so in the process the annulus gears probably moved while I was separating the parts.


Edited by Patrick Morgan, 09 March 2016 - 12:27.


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#20 Patrick Morgan

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Posted 09 March 2016 - 13:30

I feel I should explain the inaccuracy a little just so as no one can accuse me of being lax. Jade and I had been talking about doing a book on the 265E engine for some years, probably since about 2005.

 

Jade and I were both very keen to make the book technically interesting but also understandable to the general public - it's such a great human story - and we found it was extremely difficult to achieve this. We tried very, very hard and judging by the response we were reasonably successful with very few people saying it's too technical or it's not technical enough. As a part of that process Jade asked me to translate a few technical comments from the interview transcripts. In a few cases it was nearly impossible to do this without a couple of diagrams so Jade asked me if I could do a couple of sketches of the parts - we had borrowed a few bits as props to jog peoples memory during the interviews. I got carried away.... we got enough information from the parts we borrowed to model the valve gear almost exactly and we were able to measure the outside of one of the 265E engine's that at the time was in a museum. There are some photos of the parts in Karl Ludvigsen's excellent books so with all that I could create models that were pretty accurate. Mario Illien checked them all before they went to Jade.

 

One of the things Jade was very keen to do was explain the difference between the pushrod valve gear and the a standard DOHC setup. We had the added headache that the biggest readership was likely to be US based and the 265E pushrod system is very different to a small block Ford system for example.... As it happened Mark Robinson and I were rebuilding a 265D and a PC 23 so I could model the cams etc. As the variable timing system is kind of interesting I went to the trouble of modelling it as well. To be honest I just thought it would look cool in the illustration!!! 

 

As I said earlier the whole thing spun out of control, I had a wonderful time producing the drawings but I did them for the love of it and wasn't doing a lot of actual paid work.... so there were things like gear tooth numbers that were not quite right and in the case of the gearbox illustration it's at the angle it is such that you can't see that the bevel gears don't mesh properly. There just wasn't time, or the need, to get the models to the point you could make parts. 

 

Sorry, that's a very long winded explanation, it might be the tooth numbers are correct but don't rely on it.


Edited by Patrick Morgan, 09 March 2016 - 16:33.


#21 Kelpiecross

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Posted 10 March 2016 - 03:38


I may be missing something obvious here - but why such an elaborate system of gears etc. for a simple phasing of the camshafts? Most phasing systems are much simpler and involve helical splines in the drive to the camshafts.

#22 Patrick Morgan

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Posted 10 March 2016 - 08:02

I may be missing something obvious here - but why such an elaborate system of gears etc. for a simple phasing of the camshafts? Most phasing systems are much simpler and involve helical splines in the drive to the camshafts.

 

I'm fairly certain it was done this way for packaging reasons. The Helical spline arrangement adds a considerable amount of length to the cam drive, 30mm or so which in a racing engine is a big deal. 



#23 bigleagueslider

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Posted 11 March 2016 - 03:00

 

I feel I should explain the inaccuracy a little just so as no one can accuse me of being lax.

 

Patrick Morgan- I won't accuse you of being lax! In fact I think you did a fantastic job with your replies and CAD models. Made the mechanism easy to understand.

 

Also just realized you are related to one of Ilmor's founders. I look forward to reading more of your posts in the future.



#24 chunder27

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Posted 11 March 2016 - 08:22

So, this is all fascinating if you are an engine builder or engineer...

 

But the fact remains I still am no closer to knowing the facts about this Honda engine programme?  Was it VTEC or Big Bang?, ie closed together firing pulses as is now commonplace on MotoGP bikes?

 

And does anyone remember what year it was done?



#25 Patrick Morgan

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Posted 11 March 2016 - 08:45

Honda definitely tried big bang in 1994. I'm told they sounded very odd and I imagine they gave the driveline a hard time.



#26 chunder27

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Posted 11 March 2016 - 21:22

Cool, if you think they used it on 2 stroke bikes, I guess it was not surprise to see them trying a technology that revolutionised bike racing at the time in a car formula.



#27 Patrick Morgan

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Posted 15 March 2016 - 11:23

Cool, if you think they used it on 2 stroke bikes, I guess it was not surprise to see them trying a technology that revolutionised bike racing at the time in a car formula.

 

I believe the origin of big bang (please corect me if I'm wrong here, I recall an artical on this subject in Performance Bikes back in the mid 1990's) was a privateer running a 4 stroke Honda VF750 in a domestic series in the UK in the early 1980's. I can't recall the guys name but he was litterally cutting and welding cams to produce the big bang configeration. While the power output of the engine was slightly reduced the increese in overall laptime was nothing short of dramatic. Honda addopted the idea and it apeared in the RFV endrucance racers and World Superbikes before making it into the 2 stroke NSR engines in the early 1990's.

 

I will see if I can dig the artical out next week. If I recall correctly it's relevance was that PB tried big bang on an inline 4 CBR600 engine with no decernable difference other than it vibrated a bit more than the standard firing order.


Edited by Patrick Morgan, 15 March 2016 - 11:24.


#28 chunder27

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Posted 15 March 2016 - 23:17

I certainly do not recall Honda using it on any 4 stroke engines before the2 stroke NSR, but you may be right Patrick.

 

The RC30 and RVF750 bikes were fairly familiar V4 style engines at the time and all sounded very similar, you would hear a difference in engine note with a big bang firing order as you did with the NSR which sounded almost like a motocross single!, and unless HRC made a few one offs for the 8 Hour (which would be possible as they placed winningthe 8 hour over everything but the 500 title in those days) I think the tech was initially used on the V4 2 stroke in late 91 and obviously then in 92.

 

I certinaly know it was never used on the oval ppiston NR as they could never get the thing to last long enough!

 

I know Honda struggled with crankcase failures initially in the 2 stroke, as did Suzuki, Yamaha and Cagiva as they rushed through their versions later in 92 when the realised what HRC were doing, it put  alot more stress through that area!

 

be interesting to know what you dig up as I have a Honda GP racer book here but clearly that has no reference to F1 or Superbike tech details.

 

The long-bang Yamaha type deal Furusawa built for Rossi in 04 was adopted by most 4 stroke teams later. Ducati made a much less screamy bike in 04 and Kawasaki, Suzuki and Aprilia all changed their firing intervals I believe in various guises.

 

Ducati though went back to a screamer for 07 when Stoner won and Honda did too for their V4 800 as did I think Suzuki.  Weird science!


Edited by chunder27, 15 March 2016 - 23:20.


#29 bigleagueslider

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Posted 16 March 2016 - 01:37

So, this is all fascinating if you are an engine builder or engineer...

 

But the fact remains I still am no closer to knowing the facts about this Honda engine programme?  Was it VTEC or Big Bang?, ie closed together firing pulses as is now commonplace on MotoGP bikes?

 

And does anyone remember what year it was done?

All the champ car races during the 90's, except for the 500, ran under CART regs. CART engine rules did not permit any variable valve timing system, including Honda's VTEC. CART rules also required steel valve spring materials, which kept a lid on engine rpms. I believe finger type cam followers were allowed.

 

The Honda HRX & HRH engines were 2.65L V8s with a single turbocharger like most other engines at the time. B-B firing order would have been allowed, but don't know if it would have provided a benefit with the single turbocharger arrangement.

 

The only unusual characteristic of the Honda HRX engine was that it used a cast iron cylinder block. Honda switched to aluminum for the HRH engine.



#30 chunder27

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Posted 16 March 2016 - 09:57

I think I was getting confused with early 90's Honda tech!

 

I am sure it was a big bang closed firing order concept they tried, probably on Groff's car?  I think he drove with Rahal didn't he?

 

But as mentioned it was not a good concept in cars, far better in bikes, but you cant blame Honda for trying!



#31 Patrick Morgan

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Posted 16 March 2016 - 12:30

Unless I'm very much mistaken the RC30 was big bang as was the RC45. The Ducati MotoGP bikes were screemers in 2003 but then used a configuration they called "twin pulse" which is similar to big bang in concept but instead of the pistons in each bank rising and falling together they are phased slightly out. I'm pretty sure the GP7 and 8 are twin pulse although the exhaust note differs in that they are 4-2 rather than having individual pipes. I can check.

 

Back to CART - I believe variable cam timing was legal until around 1995ish but I will see if I have any old rule books to verify, it was certainly intended to be a feature for the Chevy 265C engine of 1993. Steel springs were mandated, pneumatics were outlawed in about 1995ish and desmo in around 1997. RPM was still something everyone was pushing for with Toyota up in the high 16,000rpm band by 2000 and no doubt Honda not far off. I'm told the way this was achieved was to sacrifice valve lift.

 

I realise this still does not answer the question of whether VTEC was designed into the early Honda V8 engines. But it's interesting!


Edited by Patrick Morgan, 16 March 2016 - 13:16.


#32 chunder27

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Posted 16 March 2016 - 18:26

I think you may be mistaken Pat, I am fairly sure the RC30 and RC45 were what you might call normal firing order engines. But I do not know for sure, all I do know is they sounded pretty similar to the Suzuki and Ducati V4 engines that came around much later, and I would imagine a big bang version would sound vfairly different?

 

I am just going on sound however, as they sounded very similar and very much like the RVF Suzuka bikes and TT bikes of that time, and the earlier Interceptor and very early Honda 850 V4 bikes Joey and Haslam rode in the UK, For me they all soounded the same so unless they were ALL orginally built with a closed firing order, it was only used on the 2 stroke GP 500



#33 Patrick Morgan

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Posted 16 March 2016 - 19:26

I think you may be mistaken Pat, I am fairly sure the RC30 and RC45 were what you might call normal firing order engines. But I do not know for sure, all I do know is they sounded pretty similar to the Suzuki and Ducati V4 engines that came around much later, and I would imagine a big bang version would sound vfairly different?

 

I am just going on sound however, as they sounded very similar and very much like the RVF Suzuka bikes and TT bikes of that time, and the earlier Interceptor and very early Honda 850 V4 bikes Joey and Haslam rode in the UK, For me they all soounded the same so unless they were ALL orginally built with a closed firing order, it was only used on the 2 stroke GP 500

 

 

Please don't take this the wrong way, absolutely no offence taken - my name is Patrick not Pat. 

 

I'll put a pint of Old Speckled Hen on it that the RC30 and RC45 are big bang.



#34 chunder27

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Posted 16 March 2016 - 21:57

Everyone calls me Rob, I have no issue with it!  But whatever.

 

I think you may be right about the RC30 and 45, but as most Honda's were built that way it was never known as big bang in their 4 stroke tech, only in 2 strokes. It is never referred to in books as big bang, so am presuing Honda built all their V4's that way from the RCW1000 to the VFR800 and the VF1000. Am also presuming thier modern V4 MotoGP engine is the same

 

If you check out their firing intervals, they are very similar for both types of engine, 2 and 4 stroke, but as we never really have heard a 180 degree interval V4 in a bike that I know of I think I presumed they all must be 180 degree.



#35 Patrick Morgan

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Posted 17 March 2016 - 09:47

Everyone calls me Rob, I have no issue with it!  But whatever.

 

I think you may be right about the RC30 and 45, but as most Honda's were built that way it was never known as big bang in their 4 stroke tech, only in 2 strokes. It is never referred to in books as big bang, so am presuing Honda built all their V4's that way from the RCW1000 to the VFR800 and the VF1000. Am also presuming thier modern V4 MotoGP engine is the same

 

If you check out their firing intervals, they are very similar for both types of engine, 2 and 4 stroke, but as we never really have heard a 180 degree interval V4 in a bike that I know of I think I presumed they all must be 180 degree.

 

As I said don't take offence, I'm just irrationally prickly about being called Pat! Best to get it sorted our right away though! 

 

The VF series engines (500/750/1000) were all standard firing order to the best of my knowledge, as were the VFR750F road bikes but the RC30 road and race bike was big bang and was referred to as such in any literature I've seen. A cursory look on the internet -

 

https://en.wikipedia...i/Honda_VFR750R

 

I can't say I know how the VFR800 was arranged. 



#36 Fat Boy

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Posted 21 March 2016 - 19:02

The racing engines that I've dealt with that had the ability to run a variable valvetrain have not for a couple reasons. 1. It takes away a bit of power to run the system. 2. It adds weight, complexity and things to break. 3. They don't get an advantage from it.

 

If you have an 800 HP CART engine in the 90's, then you would have only dipped into the VTEC in first gear. In first gear, you could pretty much spin the tires at will and often in second as well depending on gearing. It's just not likely that it's something anyone would spend time on.

 

Big bang is different. The RC30 and 45 had big bang variants, for sure. I'm sure there were even fire versions, but Doohan was the first to exploit it (if memory serves), and he road both.



#37 Ross Stonefeld

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Posted 21 March 2016 - 19:58

Here's a good mix of readable/nerdy on a Yamaha M1 MotoGP vis a vis The Big Bang. 

 

http://www.superbike...Dec/071217b.htm



#38 chunder27

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Posted 21 March 2016 - 22:18

As far as the 2 stroke big bang NSR500 goes. Honda had thought about doing this for years, and as it now appears the RC30 was using a big bang type config.

 

It wasn't really Doohan that used it, both he and Gardner used it in 92 and it was no doubt tested to death by guys like Beattie and Itoh who were running in the Japanese 500 (yes can you believe it there was a national 500 series then) series at the tail end of 91 and early 92.

 

Doohan didn't like it initially until he saw his laptimes!  And he dominated 92 until his crash, When he came back in 93 the bike had been engineered again towards Gardner who was a throttle jockey who rode hard but was not the same type of rider and only ever wanted power not balance. And in 93 HRC wanted to use an electronic carburettor too (it was never true fuel injection). They used it in the first race and Doohan and Beattie told them they wouldn't ride again if they were forced to use PGM Fi again!  So it was only on Itoh's bike from then on and did the magic 200mph at Hockenheim later that year (though HRC tried to tell us they hadn't)

 

And he didn't like it later on in his career when guys like Okada, Nobu Aoki and particularly Criville could look at his data and see what he was doing and use it to go as quick and push him and sometimes though rarely beat him.

 

So in 1997 he asked Honda to build a 180 version that was not Big Bang, just like the 89 engine he had that almost killed him in his debut year!

 

He did it for no other reason than to psych his opponents, and also to try and recover the close throttleconnection feeling he lad lost with the big bang engine.

What he found was fairly amazing, the electronics had moved on so much, he got BETTER tyre wear with this engine  and linked to unleaded fuel that took the edge off the power delivery as he was able to modulate the throttle much, much better. And he dominated again.

 

Criville and Okada both binned it the first time they tested it!