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Terry Prince 1350/1360 on the dyno

Terry Prince 1350/1360 on the dyno

Postby worntorn » Mon Mar 02, 2015 1:12 pm

This is Terry's race bike, with mostly the same components as in my 1360 engine. Although mine runs very strong on two 41 mm Dellortos, this result has me thinking about fuel injection. Hobot could do some sideways wheelies with this.
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Re: Terry Prince 1350/1360 on the dyno

Postby Fast Eddie » Tue Mar 03, 2015 2:00 pm

I'm sure Terry's bike is awesome. And I know that Terry is a top Vincent geezer. But surely, that has to be an opermistic dyno...?
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Re: Terry Prince 1350/1360 on the dyno

Postby worntorn » Tue Mar 03, 2015 5:35 pm

Even if it was a 15% optimistic Dynojet number(it's not a dynojet), it is still huge power. I have found Terry to be a somewhat understated individual so likely the number is correct. Afterall, Horner Bros built their first successful 1300 racer using Terry's stuff and then went on to build other versions which dynoe'd similar amounts of power to Terry's. I imagine the fellow on the Ducati 1198 who was beaten by the Horner Vincent at the Battle of the Twins would not doubt the horsepower numbers.

The real dyno test will be Bonneville and Lake Gardiner.

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Re: Terry Prince 1350/1360 on the dyno

Postby WZ507 » Wed Mar 04, 2015 9:04 pm

Glen,

Might you know the bore, stroke and IN valve size in Terry's engine?

Have you had yours on a dyno, and if so how much power does yours make?
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Re: Terry Prince 1350/1360 on the dyno

Postby worntorn » Wed Mar 04, 2015 10:51 pm

Terry's engine is 92 mm bore and 102mm stroke, identical with mine in displacement. Most components are also identical, however his engine runs 13 to one compression, fuel injection and methanol fuel. Mine is a street machine and runs 10.5 to one compression , 41 mm Dellorto Pumper carbs and premium pump gas. I have not had my engine on the dyno yet. It will produce considerably less Max power than Terry's, though still likely somewhere north of 100 rwhp, according to Terry.
Due to the light weight of the bike and the instant power delivery, I find that it hits harder than my 162 bhp Triumph Daytona.
Brutal is the best description of how the Vincent 1360 accelerates.
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Re: Terry Prince 1350/1360 on the dyno

Postby swooshdave » Wed Mar 04, 2015 10:58 pm

I can't even afford to read this thread let alone imagine what one of those engines cost. :mrgreen:
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Re: Terry Prince 1350/1360 on the dyno

Postby worntorn » Thu Mar 05, 2015 10:08 am

I've not worked it all out, but probably the costs are similar to building a real hotrod Norton engine, ie Full auto head further modded by Jim, billet cases, race crank, alloy barrels and tti trans , etc.

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Re: Terry Prince 1350/1360 on the dyno

Postby cjandme » Fri Mar 06, 2015 6:25 pm

swooshdave wrote:I can't even afford to read this thread let alone image what one of those engines cost. :mrgreen:

Your funny swooshdave :D I'm still smilin' from that post ....nice to know this stuff's out there though.
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Re: Terry Prince 1350/1360 on the dyno

Postby WZ507 » Wed Mar 11, 2015 9:27 pm

worntorn wrote:Terry's engine is 92 mm bore and 102mm stroke, identical with mine in displacement. Most components are also identical, however his engine runs 13 to one compression, fuel injection and methanol fuel. Mine is a street machine and runs 10.5 to one compression , 41 mm Dellorto Pumper carbs and premium pump gas. I have not had my engine on the dyno yet. It will produce considerably less Max power than Terry's, though still likely somewhere north of 100 rwhp, according to Terry.
Due to the light weight of the bike and the instant power delivery, I find that it hits harder than my 162 bhp Triumph Daytona.
Brutal is the best description of how the Vincent 1360 accelerates.
Glen


What size are the valves?
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Re: Terry Prince 1350/1360 on the dyno

Postby swooshdave » Wed Mar 11, 2015 10:26 pm

worntorn wrote:I've not worked it all out, but probably the costs are similar to building a real hotrod Norton engine, ie Full auto head further modded by Jim, billet cases, race crank, alloy barrels and tti trans , etc.

Glen


No matter how much money you could throw at Jim, which would be considerable, could he find 160 hp in a Norton engine. Well, he might but I bet life expectancy would be measured in seconds. :mrgreen:
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Re: Terry Prince 1350/1360 on the dyno

Postby john robert bould » Thu Mar 12, 2015 11:17 am

Terry never built a 160 brake motor. my mates 1200 RTV is half that..he talked about 100 bhp with fuel injection .

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Re: Terry Prince 1350/1360 on the dyno

Postby worntorn » Thu Mar 12, 2015 11:24 am

John, to compare the RTV 1200 Vincent to Terry's current 1360 ccracebike, which produced 165.2 rwhp on dyno, is a bit like comparing a Commando to a 2015 gixxer 1000. Though Terry had some good ideas with the RTV, it was very early days
in his experimentation. Everything that matters has been changed then changed again several times. Think modern day Burt Munro. Burt started with a bike that had perhaps 15 HP and went 60 MPH then modified it again and again until it broke 200 MPH. Terry is doing a similar thing, but started with a bit better candidate, the Vincent engine which is no slouch in stock form.
Terry bought the bike as a stock Rapide about sixty years ago when he was 17 years old and still living in England. It has had many forms over the years.

Dave, I suppose by your measure maybe the cost isn't quite so outrageous, so thanks , I will use your point as my rationalization going forward :mrgreen:

Re valve size. My engine uses standard Vincent sized valves, which are quite large, 2" for intake and 17/8" for exhaust if memory serves. Phil Irving liked to use a large valve and low lift, which made hotrodding this component easy , just add a bit of lift. Standard lift for a road going twin is just. .312" which jumps to. 343" for Irvings hotrod "Black Lightning " cams. Terry Prince went much higher , all the way to .460" with his MK4 race cam. Fritz Egli Jr. used the Mercedes Formula One Race Team's cam development program to design Terry's MK5 cams. The program said that with 6500 rpm as the intended Max output rpm, there was no point in lifting the valves more than .440 intake and. 425" exhaust, so that is what the MK5s do. Both Terry and I have these MK5s installed and they work extremely well. A nice lumpity lump no stall idle, then good controllable power just off idle, then anywhere above 2000 rpm, hang on!
I'm not sure what size valves Terry is using.

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Re: Terry Prince 1350/1360 on the dyno

Postby WZ507 » Mon Mar 23, 2015 11:52 am

Glen,

Thanks for sharing all the build details. The reason I asked about the valve size was because I wanted to back into the HP number by correlating only airflow potential from a given IN valve to power potential (assumes high compression, optimum cam and pipe). So, considering only the valve size (2.0" dia) and using literature relationships for maximum power potential from a given airflow, the following estimates were made.

A 2.0" valve in a hemi chamber (chose hemi chamber because it has higher flow potential than wedge) flowing at theoretical potential would pass ~ 200 cfm at 10" WC. In turn, this airflow in a 2 cylinder engine has the potential to support ~ 172 HP on gasoline. On alcohol the HP potential is higher (combination of higher energy content from the large alcohol charge and tolerant of higher compression than gas) and could be 240 HP. Applying a large drive train loss of 10% suggests that there is RWHP potential on gas and alcohol of 155 HP and 216 HP respectively.

In light of the above, the dyno numbers Terry cited certainly appear to be well within the realm of reality for a well prepared race engine realizing the full airflow potential of a 2" IN valve. In his favor, the fact that he has FI, and presumably has large throttle bodies, serves to minimize flow losses that occur with carbs. His result suggest that airflow is well below entitlement, which would not be surprising given that the Vincent head/induction system was likely not optimized for flow.

One specification associated with the build that puzzles me is the low valve lift of 0.440". I assume you have quoted valve lift, not cam lift? Is that true?
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Re: Terry Prince 1350/1360 on the dyno

Postby worntorn » Mon Mar 23, 2015 1:05 pm

That's correct, .440" is valve lift.
I should point out that these heads appear outwardly to be the same as conventional Vincent heads, but are actually different in almost every way. Inlet port size on a standard Vincent head is 28mm, Terry's are at 42 mm (mine are at 38 mm)and very different in shape from many years of trial and error plus flow bench testing. Additionally, the combustion chambers are twin plug bathtub shaped with large squish vs single plugged hemi with no squish for a standard Vin. Exhaust ports are filled in at bottom to form a sideways D for exhaust reversion prevention.
He has also made improvements to the rocker bearings(doubled the surface area), improved the rocker oil feed connection to a leak proof design and added 25 % more fin area for cooling.

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Re: Terry Prince 1350/1360 on the dyno

Postby WZ507 » Tue Apr 07, 2015 8:50 pm

worntorn wrote:That's correct, .440" is valve lift.
I should point out that these heads appear outwardly to be the same as conventional Vincent heads, but are actually different in almost every way. Inlet port size on a standard Vincent head is 28mm, Terry's are at 42 mm (mine are at 38 mm)and very different in shape from many years of trial and error plus flow bench testing. Additionally, the combustion chambers are twin plug bathtub shaped with large squish vs single plugged hemi with no squish for a standard Vin. Exhaust ports are filled in at bottom to form a sideways D for exhaust reversion prevention.
He has also made improvements to the rocker bearings(doubled the surface area), improved the rocker oil feed connection to a leak proof design and added 25 % more fin area for cooling.
Glen


I did a little diddling regarding the estimated port speed of your engine and I think your port size of 38 mm is perfect to achieve optimum port speed.

I asked about valve lift because 0.440" is really low lift for a 2" valve in an OHV engine. A lift of 0.440" is only 22% of the valve dia, which is more typical of the lift employed on a flathead engine (poor breathing relative to OHV), where 40% of the valve is masked, flow tends to be more across the valve than around it, and flow maximizes between 20-25%. At a valve lift of 25% the curtain area equals the valve area, thus this is usually the minimum lift employed in an OHV application, but more common is 30% and in NASCAR I believe flow increases up to 35%.

Is there some fundamental reason or limitation of the system that requires such a low lift? Too much x-over flow between IN & EX in the bathtub? I can't imagine the airflow potential of a 2" valve is realized when lifted 22% of the valve dia, but I don't know the head or port so possibly it is?

As always I suspect there is much more to the story, so I'll stay tuned for your response.
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