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5th & 6th VFR 800 Header build


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One more thing: if you want to be put down on the initial list of 25 interested parties please supply a full name and address (for shipping), and ideally a phone number and email so Jeff can get in touch if needed. 

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Update: 

 

Here’s Jeff’s bike on its way to a race engineer’s workshop (British Talent Cup) for an oil and filter change before the dyno. 

 

476AFF2F-7F24-416B-9D15-09B3E48DA81D.thumb.jpeg.6892bf533be87b65917f6d1754546264.jpeg

 

Jeff is also going to drop a Lextek air filter into the mix. 

 

Really excited about this now! 

 

Stray 

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36 minutes ago, SEBSPEED said:

Make sure the air filter goes in for the stock run first, to avoid muddying the results with multiple variables. 

 I'll second this. 😉

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Yup, air filter will go in during service - before any dyno runs. Same with end can. 

 

No fuel management I’m afraid. Jeff is too busy to mess with that sort of fine tuning. 

 

Best we can expect is a simple dyno run before and another simple dyno run after fitting the new header. No dyno tuning - just dyno measurement. 

 

Frankly we are lucky to get this much from a very obliging and generous supplier. 

 

Stray

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1 hour ago, Stray said:

Yup, air filter will go in during service - before any dyno runs. Same with end can. 

 

No fuel management I’m afraid. Jeff is too busy to mess with that sort of fine tuning. 

 

Best we can expect is a simple dyno run before and another simple dyno run after fitting the new header. No dyno tuning - just dyno measurement. 

 

Frankly we are lucky to get this much from a very obliging and generous supplier. 

 

Stray

It's probably god enough for most people's purposes. Same bike, same day, same dyno, and same filtration (only difference being headers), should give a good enough guide as to real-world gains from the aftermarket header.

 

Oh, and if we can get the measured weights for the standard and aftermarket header, that too would be handy...

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A rough idea is all you can hope for and will be good enough.

You have to keep in mind that the 00/01 had a few changes from the 98/99.

When the 00 introduced the cat, the exhaust headers were made of smaller diameter to help heat up the coverter as quickly as possible.

This in turn requiered a different fuel map to oveturn loses from the restrictive pipes and bring HP back to were the 98/99 was.

The press release at the time stated that fuel efficiency was up on the 00 because of this.

So my educated guess is that the 00/01 will produce more HP than the 98/99 with the 98/99 headers.

So seeing an increase of HP using these new pipes on an 01, doesnt reliably mean that you will get an increase of power on a 98/99.

Don't get me wrong, I'm happy to see a good set of pipes being made, and will seriously consider getting rid of my Delk's on my 01 if power is up.

The Delk's are a nice looking pipe, but the collector is an El Cheapo design that hasn't got a hope in hell of being a performance pipe.

I got mine because the original pipes looked like shit, and had a couple of dings in them and couldn't find a 98/99 set.

 

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Now that is a first for me to read. Good find there,  and yes, explains a bit or two,  then on the last page about the clutch.   yes,  interesting.

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On 11/7/2018 at 11:45 AM, BiKenG said:

I am still trying to establish how Delkevic can use the same collector for 5 and 6 Gen systems. Is the outlet angle and position the same on these bikes with just a different link from there to the low can of the 5th Gen or the high level stuff under the seat of the 6th Gen?

 

As I said, I'm needing the splayed front pipes of the 8th Gen with an outlet suitable for the 6th Gen's high level and although modification of the pipes to suit may be necessary, the less needed the better. So just trying to understand what might be required.

 

Anyone know for sure about the outlets?

 

Hi Ken,  5+6th gens have outlets in the same place & the exhaust pairings are the same. But on 5th gen the #1 cylinder (rear left) header runs around the outside of the #3 header, making it longer  & accounting for the disparate vacuum readings when balancing the TB’s. On the 6th gen Honda corrected this, by bringing #1 header under & inside #3 header thus making them the same length, but that meant they had to cross the front header pipes to keep the port pairing the same. So 6th gen have crossed front & rear pipes & 5th gen have no crosses. 

 

The port pairing on the 5/6th gens gives the best exhaust scavenge effect. But the gains are not great, due to the odd firing order.

A correctly sized header with 8th gen port matching should work just as well. Looking at this new header it appears to have stepped or a poor mans tapered header which is all the rage in MotoGP systems.

 

For reference the TBR system on mine added 8hp after a little fuel adjustment, but was good for 6hp without fuelling update. Power went from 112hp to 120hp same configuration, same dyno, all that changed was the exhausts from Motad to TBR.

 

If the 5.7kg mentioned is just the header, then that’s heavy, compared to TBR at 4kg, but lighter than stock, especially if you have a cat exhaust which adds 2kg by itself.

 

YMMV

 

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5 hours ago, VFROZ said:

This makes interesting reading:

98-99 to 00-01 VFR800 Difference.pdf

 

Interesting reading for sure, but something is not adding up.

 

I am not interested in max power figures, except for comparison purposes. In that Honda doc, they state the 5.2 makes 106 PS and the provided graph, while not including any figures shows the 5.2 making quite a bit more than the 5.1 they show for comparison. In fact from that Honda graph, a very rough estimate would put the 5.1 at no more than 100 PS. Yet figures I have for the 5.1 state 110 HP. Now I realise that PS are slightly bigger than traditional HP so the number would be slightly lower, but certainly not 10%.

 

Those 5.1 figures are not from Honda literature, but from some press info. However, it is almost certainly simply copied from Honda's own literature at the time. So either I'm missing something here, or someone's being economical with the truth.

 

BTW, Honda's figures for the Gen 6 are 107 PS max. So certainly same ballpark. The 8th Gen dropped to 104.

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It is actually a Honda press release given to explain what was new on the 5G.

The 5.2 shows two different power ratings(106 and 110), it looks like it’s at different standards. 

I thought I would add this as well to compare to the old 750:

 

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4 hours ago, VFROZ said:

It's a video showing all the techical differences from the 750 to the new 800. 

I'm getting a 'No video with supported format and MIME type found' message...

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13 hours ago, Mohawk said:

 

Hi Ken,  5+6th gens have outlets in the same place & the exhaust pairings are the same. But on 5th gen the #1 cylinder (rear left) header runs around the outside of the #3 header, making it longer  & accounting for the disparate vacuum readings when balancing the TB’s. On the 6th gen Honda corrected this, by bringing #1 header under & inside #3 header thus making them the same length, but that meant they had to cross the front header pipes to keep the port pairing the same. So 6th gen have crossed front & rear pipes & 5th gen have no crosses. 

 

The port pairing on the 5/6th gens gives the best exhaust scavenge effect. But the gains are not great, due to the odd firing order.

A correctly sized header with 8th gen port matching should work just as well. Looking at this new header it appears to have stepped or a poor mans tapered header which is all the rage in MotoGP systems.

 

For reference the TBR system on mine added 8hp after a little fuel adjustment, but was good for 6hp without fuelling update. Power went from 112hp to 120hp same configuration, same dyno, all that changed was the exhausts from Motad to TBR.

 

If the 5.7kg mentioned is just the header, then that’s heavy, compared to TBR at 4kg, but lighter than stock, especially if you have a cat exhaust which adds 2kg by itself.

 

YMMV

 

 

Thanks for providing the before and after numbers of a viable A vs B test where you only changed one variable - the headers. It seems tricky to communicate the importance of such comparisons to enthusiasts who have just received exciting new parts.

 

Mohawk, does your TBR widen at all from the cylinder head port, or is it constant-diameter tubing through the length of the primary? Just curious how much nuance TBR put into their headers. TBR tubing size choices are proven performance improvements - specifically their 38mm o.d. (IIRC) primaries.

 

In theory, the velocity of a gas moving in a tube decreases when it encounters an increase in tubing diameter. It appears the Lextek header is keeping the primary diameter smaller from the port (actual exhaust port i.d. exiting the head is 32.45mm) down the primary, probably to keep gas velocity higher before widening the primary diameter - higher velocity through and past the port increases scavenging of exhaust gases from the cylinder.

 

It will be interesting to see what comes of the dyno runs with stock (albeit 5.2 w cat) vs Lextek headers.

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12 hours ago, BiKenG said:

 

Interesting reading for sure, but something is not adding up.

 

I am not interested in max power figures, except for comparison purposes. In that Honda doc, they state the 5.2 makes 106 PS and the provided graph, while not including any figures shows the 5.2 making quite a bit more than the 5.1 they show for comparison. In fact from that Honda graph, a very rough estimate would put the 5.1 at no more than 100 PS. Yet figures I have for the 5.1 state 110 HP. Now I realise that PS are slightly bigger than traditional HP so the number would be slightly lower, but certainly not 10%.

 

Those 5.1 figures are not from Honda literature, but from some press info. However, it is almost certainly simply copied from Honda's own literature at the time. So either I'm missing something here, or someone's being economical with the truth.

 

BTW, Honda's figures for the Gen 6 are 107 PS max. So certainly same ballpark. The 8th Gen dropped to 104.

 

That is a Honda Press Release.  I think it (and the video) were from the dump of press docs I posted here a couple of years ago (from my time as a "journalist" haunting EICMA and INTERMOT).  The other ones I have are attached below.

 

Although these press releases all related to the ED-Type model, Honda wasn't always quoting PS power figures according to DIN, sometimes it was 95/1/EC, and sometimes both.  As you can see, they quoted the same figures for the FiW (5.1) and the FiY (5.2); what's missing is any figures for the FiW-X catalyser models (e.g., Swiss, German), which were presumably 8PS lower (according to the FiY Press Release).

 

Honda usually also published more comprensive information on "new" models, which was provided to dealers or service managers.  I've got one binder on the RC45 (in German, unfortunately) that's 50 pages of technical info.  I wish I had something similar for the bikes I actually own!

 

Ciao,

 

JZH

Honda VFR800FiW Press Information.pdf

Honda VFR800FiX Press Information.PDF

Honda VFR800Fi1 Press Information.pdf

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TBR headers are constant diameter, you are correct in your recollection of 38mm OD with 1mm wall, so 36mm ID which was the OD of the Motad header which is a copy of the 98/99 catless header. The Motad has a 1.5mm wall thickness so ID is 33mm, but the exhaust clamp flange weld reduces that internally to 29mm. So Motad to TBR swap changed the ID from 29mm to 36mm & this shows in how the power with the Motad plateau’d at 10500rpm, but the TBR kept increasing to the rev limiter at 12200rpm, with NO losses ! 

 

I had a contact in Japan confirm the Ladybird RC45 Titanium HRC copy is 38mm OD with 1mm wall thickness, so apart from being lighter & much more expensive, TBR got the dimensions right. 

 

I used Suzuki GSXR750 exhaust gaskets, with the TBR as Honda standard sized ones are smaller than the exhaust port when crushed ! 

 

Be good to see the numbers on this new exhaust. 

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19 hours ago, VFROZ said:

 

So my educated guess is that the 00/01 will produce more HP than the 98/99 with the 98/99 headers.

 

 

I won't dispute that out of hand ('cos I don't know), but I'd be very interested to see back-to-back dynos of a '98/'99 and an '00/'01 with the same exhaust setup (whether the 98/99 headers or these new "you beaut" ones).

 

And yes, I'm happy enough to keep my '99 headers if nothing better presents itself.

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6 hours ago, Mohawk said:

TBR headers are constant diameter, you are correct in your recollection of 38mm OD with 1mm wall, so 36mm ID which was the OD of the Motad header which is a copy of the 98/99 catless header. The Motad has a 1.5mm wall thickness so ID is 33mm, but the exhaust clamp flange weld reduces that internally to 29mm. So Motad to TBR swap changed the ID from 29mm to 36mm & this shows in how the power with the Motad plateau’d at 10500rpm, but the TBR kept increasing to the rev limiter at 12200rpm, with NO losses ! 

 

I had a contact in Japan confirm the Ladybird RC45 Titanium HRC copy is 38mm OD with 1mm wall thickness, so apart from being lighter & much more expensive, TBR got the dimensions right. 

 

I used Suzuki GSXR750 exhaust gaskets, with the TBR as Honda standard sized ones are smaller than the exhaust port when crushed ! 

 

Be good to see the numbers on this new exhaust. 

 Good to know on the exhaust gaskets 😉  I just figured nothing would work, so made em myself

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On 11/15/2018 at 6:00 AM, keef said:

Mohawk, what year gsxr 750 gaskets, or are all the same?

Hi Keef, I can’t recall the exact model. But any 42mm OD gasket will do. I prefer the crushable copper ones. 

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5 hours ago, Mohawk said:

 

Hi Keef, I can’t recall the exact model. But any 42mm OD gasket will do. I prefer the crushable copper ones. 

Cheers mohawk- i had a feeling they were mostly the same. 

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On 11/14/2018 at 3:10 AM, Mohawk said:

 

Hi Ken,  5+6th gens have outlets in the same place & the exhaust pairings are the same. But on 5th gen the #1 cylinder (rear left) header runs around the outside of the #3 header, making it longer  & accounting for the disparate vacuum readings when balancing the TB’s. On the 6th gen Honda corrected this, by bringing #1 header under & inside #3 header thus making them the same length, but that meant they had to cross the front header pipes to keep the port pairing the same. So 6th gen have crossed front & rear pipes & 5th gen have no crosses. 

 

 

YMMV

 

 

They actually started in 2000 with the Cat Con and crossed front headers. A friend had a Euro model '98 or '99 that also had crossed front headers. No idea if it came like that from the factory, but not much else was changed. I forget if it had a cat.

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