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VFR 800 F - Development story


Kwee69

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Hi there,

I just found the development story of the VFR 800 F. 

https://ultimatemotorcycling.com/2014/07/30/2014-honda-vfr800-f-interceptor-development-story/

 

https://www.motorcyclistonline.com/reviews/honda-vfr800-interceptor-road-test#page-7

 

I've few mecanicals questions about the VFR 800 F. 

 

About the camshaft, in this article says 

"Revisions to the Interceptor’s intake cams—they have 6 degrees more duration and open 3 degrees earlier—help fill in the torque curve around VTEC activation. Still, 94 hp isn’t exactly stunning."

 

For me, this mean the intake valve is open 3 degrees earlier + 6 degrees more duration, mean for me 

Advance intake, so more overlap = more rpm power, less low rpm power

 

I'm right ?

 

To increase overlap, you have to RETARD the EXHAUST, and/or ADVANCE the INTAKE.
To reduce overlap, you have to ADVANCE the EXHAUST, and/or RETARD the INTAKE.

Simple cam tuning rules for NATURALLY ASPIRATED engines:

* Advancing both cams => more low-RPM power, less high-RPM power
* Retarding both cams => more high-RPM power, less low-RPM power
* Less overlap => more low-RPM power, less high-RPM power
* More overlap => more high-RPM power, less low-RPM power

 

 

I know that longer funnels in the air intake system improve mid torque

 

Screenshot_20180117-110938.png

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What's the question?

 

 

Marc Cook doesn't like VFR's.  Does anybody really care what he thinks?  

 

"Engine tuning now places a strong emphasis on low-end and midrange power."  

 

True statement in the real world.  The 8th gen. performs better in tight twists than either the 5th or 6th gen. I've had,.... my experience.  The 8th gen. is allegedly less than 10 mph slower on top end.  How many people know what the actual top end speed of their bike is?  Is anyone using their VFR at Bonneville?  

 

How many people use the low-end and midrange power (torque) curve the vast majority of the time?.....almost everyone.  

 

Motorcycle magazines exist to sell ads and make a profit from that but your mechanical questions and aptitude are understandable.  Bottom line is the 8th gen. uses torque noticeably better than past generations in my experience without the persistent "Honda wiring and electrical design problems."   Yada, yada, yada.....   

 

 

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Hi,

 

My question is about camshaft, advance, overlap, etc. What is the main difference between 6 gen and 8 gen on this point.

 

"

About the camshaft, in this article says 

"Revisions to the Interceptor’s intake cams—they have 6 degrees more duration and open 3 degrees earlier—help fill in the torque curve around VTEC activation. Still, 94 hp isn’t exactly stunning."

 

For me, this mean the intake valve is open 3 degrees earlier + 6 degrees more duration, mean for me 

Advance intake, so more overlap = more rpm power, less low rpm power

 

Intake valve open earlier and close later = more overlap

 

I'm right ?

 

To increase overlap, you have to RETARD the EXHAUST, and/or ADVANCE the INTAKE.
To reduce overlap, you have to ADVANCE the EXHAUST, and/or RETARD the INTAKE.

Simple cam tuning rules for NATURALLY ASPIRATED engines:

* Advancing both cams => more low-RPM power, less high-RPM power
* Retarding both cams => more high-RPM power, less low-RPM power
* Less overlap => more low-RPM power, less high-RPM power
* More overlap => more high-RPM power, less low-RPM power"

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Honda improve low mid power and torque by using longer funnel intake but that's decrease high power so they increase intake valve duration for compensating the lost.

 

Which mean :

Gen 6 + Gen 8 intake camshaft = more power, less low mid torque(hard to do)

Gen 8 + Gen 6 funnel intake = more power, less low mid torque(easy to do)

 

 

 

 

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Vfr 2014   Inlet  Open 15 BTDC , Close 30 ABDC   ,    Exhaust    Open 35 BBDC, Close  10 ATDC .

 

V fr 2005  Inlet  Open 12 BTDC, Close 30 ABDC    .  Exhaust    Open 35 BBDC,   Close 10 ATDC.

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8 minutes ago, fink said:

 

Vfr 2014   Inlet  Open 15 BTDC , Close 30 ABDC   ,    Exhaust    Open 35 BBDC, Close  10 ATDC .

 

V fr 2005  Inlet  Open 12 BTDC, Close 30 ABDC    .  Exhaust    Open 35 BBDC,   Close 10 ATDC.

Thanks ! Where did you get that ? 

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2 hours ago, Tiutis said:

Not sure how comparable these dyno graphs are but here is 02 vs 14. It kind of confirms 14's a little meatier torque curve under 2 valves, less peak tq but also quicker Hp drop off near the top. 

https://www.motorcyclistonline.com/2002-honda-interceptor#page-11

image.png.6cf627a951decff8c2b36d4e3ddd5967.png

image.png.52abf2f509cf9bf5bf44b2b2ff2c4f6a.png

Don't compare peak horse power and torque. Some bikes are closer to manufacturer numbers and some manufacturers are a more conservative than others. But compare curve and where the power and torque start to decrease. 

In Europe, some VFR 800 dyno around 99 hp(Akrapovic data), 103 hp(motostation) at the wheel

There is slightly difference between US bike and Europe(fuel) and pollution(EVAP Cannister on californians models) and the new 2017 model is rated at 107,5 hp and 79 Nm(around 58 lbs.ft) 

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47 minutes ago, Kwee69 said:

Don't compare peak horse power and torque. Some bikes are closer to manufacturer numbers and some manufacturers are a more conservative than others. But compare curve and where the power and torque start to decrease. 

In Europe, some VFR 800 dyno around 99 hp(Akrapovic data), 103 hp(motostation) at the wheel

There is slightly difference between US bike and Europe(fuel) and pollution(EVAP Cannister on californians models) and the new 2017 model is rated at 107,5 hp and 79 Nm(around 58 lbs.ft) 

Both of those graphs are from the same motorcycleonline.com site. Hopefully they used the same dyno and dynoed in similar weather conditions and 02 and the 14 vfrs

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3 hours ago, Tiutis said:

Both of those graphs are from the same motorcycleonline.com site. Hopefully they used the same dyno and dynoed in similar weather conditions and 02 and the 14 vfrs

That's exactly why i said "Some bikes are closer to manufacturer numbers and some manufacturers are a more conservative than others." 

We all know that VFR 800 VTEC and VFR 800 F output the same power. There is many dyno here and there. Between 94 hp and 103 hp at the rear wheel, never see higher with stock muffler. 

 

Compare the curve between 5 gen, 6 gen and 8 gen is way more important

 

the 2014 engine is the one we waited 12 years ago

130top-testhondavfr-800-fmotorjpg.jpg

imageproxy-2.jpg

post-8974-0-72075400-1406364066.jpg

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5 hours ago, Kwee69 said:

That's exactly why i said "Some bikes are closer to manufacturer numbers and some manufacturers are a more conservative than others." 

We all know that VFR 800 VTEC and VFR 800 F output the same power. There is many dyno here and there. Between 94 hp and 103 hp at the rear wheel, never see higher with stock muffler. 

 

Compare the curve between 5 gen, 6 gen and 8 gen is way more important

 

the 2014 engine is the one we waited 12 years ago

130top-testhondavfr-800-fmotorjpg.jpg

imageproxy-2.jpg

post-8974-0-72075400-1406364066.jpg

Sorry, I don't understand your comment, when I'm comparing dyno numbers and not peak manufacturer numbers of the same manufacturer.

All I wanted to add to this post is to point out that at first look the 6 to 8 gen dyno make 8th gen seem as a detune. It appears that 8 gen lost more peak tq and hp than it gained in the mid range. However, when you consider the the gas mileage improvements and the improved transition from 2-4 valves, than it start to make more sense why those improvements were.  

 

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6 hours ago, Tiutis said:

Sorry, I don't understand your comment, when I'm comparing dyno numbers and not peak manufacturer numbers of the same manufacturer.

All I wanted to add to this post is to point out that at first look the 6 to 8 gen dyno make 8th gen seem as a detune. It appears that 8 gen lost more peak tq and hp than it gained in the mid range. However, when you consider the the gas mileage improvements and the improved transition from 2-4 valves, than it start to make more sense why those improvements were.  

 

8 gen detune ? The output power is the same = 106 hp on the 5, 6 et 8 gen but not at the same rpm.

VFR 800 FI = 106 hp at 10500 rpm, 80 Nm at 8500 rpm

VFR 800 VTEC = 106 hp at 10750 rpm, 80 Nm at 8750 rpm

VFR 800 F = 106 hp at 10250 rpm, 75 Nm at 8500 rpm

 

As you can see the VFR 800 VTEC should push more rpm for output the same power. And the torque curve is bad on this one. The VFR 800 FI curve is way better. Peak torque on the VTEC is just a little spike before it run out of breath. That's bad man :/

 

We want power as soon as possible(better acceleration)

 

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Whilst I appreciate the esoterics of this discussion, in our practical, day-to-day riding life, what does it matter, a hp here or a Nm there? We all love the VFRs we have and whilst we do all have our own opinions about which version we prefer, those are personal opinions and only really valid for ourselves.

 

Kwee69 - do you know what they've done to the engine to quote an increase in power & torque for the 2017 model? I didn't see that in any advertising literature or test reports.

 

16 hours ago, Kwee69 said:

....and the new 2017 model is rated at 107,5 hp and 79 Nm(around 58 lbs.ft) 

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41 minutes ago, Skids said:

Whilst I appreciate the esoterics of this discussion, in our practical, day-to-day riding life, what does it matter, a hp here or a Nm there? We all love the VFRs we have and whilst we do all have our own opinions about which version we prefer, those are personal opinions and only really valid for ourselves.

 

Kwee69 - do you know what they've done to the engine to quote an increase in power & torque for the 2017 model? I didn't see that in any advertising literature or test reports.

 

I love all the VFR, specifically VFR 800 VTEC look. But that's a shame that Honda fuck up the engine is this motorbike... 

Torque at low mid RPM is what we want for cruising. VTEC was sold with this in mind, more torque at low mid RPM but that's not what we see in real. They reduce 3rd gear and down a tooth of front sprochet for counter the reduce in torque.

 

Only in Europe. There

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Screenshot_20180114-220453.png

entry226g1-1.jpg

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So according to that chart, for the '17 refresh the power went up by one thingamajiggie and the torque went up by 2 thingamajigiies at the same rpm as the original 8th gen?  Is this at the crank or at the wheel?   I wasn't aware of any engine tweaks for the '17 refresh, so I assume this is just the result of the revised exhaust system? 

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4 hours ago, GatorGreg said:

So according to that chart, for the '17 refresh the power went up by one thingamajiggie and the torque went up by 2 thingamajigiies at the same rpm as the original 8th gen?  Is this at the crank or at the wheel?   I wasn't aware of any engine tweaks for the '17 refresh, so I assume this is just the result of the revised exhaust system? 

Euro 4 laws here, no more 106 hp restriction in France. In Japan, no more restrictions.(manufacturers talk about crankpower with accessory = alternator, etc but without the gearbox)

I think they just add some power and torque here and there, just because they can. Not really an upgrade.

 

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Anti-rust treatment fail?? :unsure:

 

 

 

 

0404ba7309ef8b863894fe0abc6660f1.thumb.jpg.295ca6caa729970d8c596b77742eaba4.jpg

 

 

 

:goofy:

 

 

 

 

 

Fwiw, my 4th gen did 106 RWHP..... 79Nm @7839RPM

 

 

 

 

 

 

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1 hour ago, Dutchy said:

Anti-rust treatment fail?? :unsure:

 

 

 

 

0404ba7309ef8b863894fe0abc6660f1.thumb.jpg.295ca6caa729970d8c596b77742eaba4.jpg

 

 

 

:goofy:

 

 

 

 

 

Fwiw, my 4th gen did 106 RWHP..... 79Nm @7839RPM

 

 

 

 

 

 

Just a cover, 4 gen VFR 750 F curve is better at low rpm than 5 Gen, 6 Gen and 8 Gen xD. Carb For The Win !

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17 hours ago, Kwee69 said:

8 gen detune ? The output power is the same = 106 hp on the 5, 6 et 8 gen but not at the same rpm.

VFR 800 FI = 106 hp at 10500 rpm, 80 Nm at 8500 rpm

VFR 800 VTEC = 106 hp at 10750 rpm, 80 Nm at 8750 rpm

VFR 800 F = 106 hp at 10250 rpm, 75 Nm at 8500 rpm

 

As you can see the VFR 800 VTEC should push more rpm for output the same power. And the torque curve is bad on this one. The VFR 800 FI curve is way better. Peak torque on the VTEC is just a little spike before it run out of breath. That's bad man :/

 

We want power as soon as possible(better acceleration)

 

6 vs 8 is not the same peak hp-look at the dynographs I posted. 6th gen has a little more aggressive cams and thats why it makes top power a tiny bit later in the powerband. But, it's all bean counting.

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2 minutes ago, Tiutis said:

6 vs 8 is not the same peak hp-look at the dynographs I posted. 6th gen has a little more aggressive cams and thats why it makes top power a tiny bit later in the powerband. But, it's all bean counting.

Nope :/

Vfr 2014   Inlet  Open 15 BTDC , Close 30 ABDC   ,    Exhaust    Open 35 BBDC, Close  10 ATDC .

 

V fr 2005  Inlet  Open 12 BTDC, Close 30 ABDC    .  Exhaust    Open 35 BBDC,   Close 10 ATDC.

 

To increase overlap, you have to RETARD the EXHAUST, and/or ADVANCE the INTAKE.
To reduce overlap, you have to ADVANCE the EXHAUST, and/or RETARD the INTAKE.

Simple cam tuning rules for NATURALLY ASPIRATED engines:

* Advancing both cams => more low-RPM power, less high-RPM power
* Retarding both cams => more high-RPM power, less low-RPM power
* Less overlap => more low-RPM power, less high-RPM power
* More overlap => more high-RPM power, less low-RPM power"

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10 hours ago, Dutchy said:

Anti-rust treatment fail?? :unsure:

 

 

 

 

0404ba7309ef8b863894fe0abc6660f1.thumb.jpg.295ca6caa729970d8c596b77742eaba4.jpg

 

 

 

:goofy:

 

 

 

 

 

Fwiw, my 4th gen did 106 RWHP..... 79Nm @7839RPM

 

 

 

 

 

 

 

:tongue: VFR = Very Fast Rust

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