Project 100hp rephased 880

howardsmed

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Good morning to you all

I have previously posted the dyno results from our rephased 880cc engine we built for sidecar road racing. The engine design and build has been undertaken as a collaboration between Howard ( ex Smedspeed) Steve Mann and Rick Forte. To date we have achieved 90hp rear wheel at 7500rpm, and a torque spread of over 65lbs/ft from 3500-7500rpm, all the dyno work we have needed done is performed on the same dyno by veteran racer and tuner Ricard Albans at TTS in Northampton. There is as you can imagine a lot of development and updated design work required to squeeze 90hp out of a 50 year old design, but I have a long history of motorcycle parts design so that part fell to me. Steve Mann did all the machining and design for the "raised port" heads, and indeed all the engine build work, I did the crank rephase and machining work on the crank cases.

When the bike was run on the dyno some six months ago, we must have asked Richard not to rev it too hard, which he duly did.. ..the 90hp whilst a superb achievement is actually still well below the accepted maximum accepted piston speed for even a street engine, this would occur ( assuming 4000ft/minute is used) at just over 8200rpm, with this in mind we are returning to the dyno and will use the 8238rpm x 1.05 giving us 8650rpm. It is common practice when engines are developed and tested to use a "test rpm" figure, this is for most engines, (and this depends on the manufacturer) 1.10 x the stock redline.
The dyno sheet we have currently, do not show the power or torque "nosing over" which is where the engine runs out of breath. We believe/hope that the engine will create torque and thus hp to a higher figure than 7500rpm. At present the many calculations and simulations suggest that we will obtain 94hp at 8200rpm.

Despite having such a good power output, this engine is still not a race engine, its max rpm is at the stock point, it runs on good fuel ( which in the UK is 99 octane ) and it doesn't require mach pre race attention other than checking tappets and plugs. it is essentially still just a VERY fast street engine.

So this winter we are fitting larger 45mm diameter 7mm stem valves, this will require new collets and top collars and guides to suit. I have sourced some required parts from a well known American manufacturer to save us making them ourselves. Most parts will be designed by and made here in the UK, all this with slightly higher compression and some revised port work and a higher redline we hope to achieve somewhere 100hp rear wheel.

I hear all the nay-sayers chime in with negativity, BUT how can you do it ? when Yamaha could not.

Well "back in the day" there were no £85,000 valve seat cutting machines, no programable CDi ignitions , no hot plateau honing, these days all the modern machinery and simulation programmes that allow manufacturers and skilled individuals alike to achieve outputs that 50 years ago were unheard of.

Ask yourself how much has your phone advanced in just the last 20 years ???

We will keep you informed

Howard
 

Bewarethemoon

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Good morning to you all

I have previously posted the dyno results from our rephased 880cc engine we built for sidecar road racing. The engine design and build has been undertaken as a collaboration between Howard ( ex Smedspeed) Steve Mann and Rick Forte. To date we have achieved 90hp rear wheel at 7500rpm, and a torque spread of over 65lbs/ft from 3500-7500rpm, all the dyno work we have needed done is performed on the same dyno by veteran racer and tuner Ricard Albans at TTS in Northampton. There is as you can imagine a lot of development and updated design work required to squeeze 90hp out of a 50 year old design, but I have a long history of motorcycle parts design so that part fell to me. Steve Mann did all the machining and design for the "raised port" heads, and indeed all the engine build work, I did the crank rephase and machining work on the crank cases.

When the bike was run on the dyno some six months ago, we must have asked Richard not to rev it too hard, which he duly did.. ..the 90hp whilst a superb achievement is actually still well below the accepted maximum accepted piston speed for even a street engine, this would occur ( assuming 4000ft/minute is used) at just over 8200rpm, with this in mind we are returning to the dyno and will use the 8238rpm x 1.05 giving us 8650rpm. It is common practice when engines are developed and tested to use a "test rpm" figure, this is for most engines, (and this depends on the manufacturer) 1.10 x the stock redline.
The dyno sheet we have currently, do not show the power or torque "nosing over" which is where the engine runs out of breath. We believe/hope that the engine will create torque and thus hp to a higher figure than 7500rpm. At present the many calculations and simulations suggest that we will obtain 94hp at 8200rpm.

Despite having such a good power output, this engine is still not a race engine, its max rpm is at the stock point, it runs on good fuel ( which in the UK is 99 octane ) and it doesn't require mach pre race attention other than checking tappets and plugs. it is essentially still just a VERY fast street engine.

So this winter we are fitting larger 45mm diameter 7mm stem valves, this will require new collets and top collars and guides to suit. I have sourced some required parts from a well known American manufacturer to save us making them ourselves. Most parts will be designed by and made here in the UK, all this with slightly higher compression and some revised port work and a higher redline we hope to achieve somewhere 100hp rear wheel.

I hear all the nay-sayers chime in with negativity, BUT how can you do it ? when Yamaha could not.

Well "back in the day" there were no £85,000 valve seat cutting machines, no programable CDi ignitions , no hot plateau honing, these days all the modern machinery and simulation programmes that allow manufacturers and skilled individuals alike to achieve outputs that 50 years ago were unheard of.

Ask yourself how much has your phone advanced in just the last 20 years ???

We will keep you informed

Howard

Wow! A near 100hp street engine!? Great post Howard!

I for one will be watching this thread fervently!

Daniel.
 

howardsmed

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Richard Albans only assists in running the dyno, we give him the list of actual tests we want run. Most people just run at full throttle and want to see a torque and hp figure, we do not.
Lambda, EGT, response time, part throttle load response etc.

I will post another sheet when we do another test.
 

Signal

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100HP will put you up with the Maney Nortons and fast BMWs here in NZ. . Still chipping away with those big bore parts I got from you.
Watching with great interest, thanks for posting.
 

howardsmed

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Steve Maney has virtually packed the business up, and am told has moved to Thailand. We race the BMWs here built by ( Richard Morre) Moorespeed, in fact we both use the same dyno firm. he gets around 100hp per litre from most engine sizes, we won the 750 class championship last year with a very reliable engine that put out 74hp. I know I keep saying it, but that really was a street engine, Wossner pistons, cam from Smedspeed, all parts that available over the counter.
When you get it closer, email me and i will give you the details of the cam to use and the raised port heads, the parts I sold you are exactly what we are using.
The really big engines run out of breath a little at 8000rpm +. so we are having made some 7mm stem, 45mm head stainless valves, also beehive springs.

One of my oldest friends Fergus Maynes lives in NZ ( Takapuna) he races there too

H
 

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Hi Howard,

I’m also slowly chipping away at the engine parts list you wrote for me shortly after you sold the business to Ricki.

Very interested in the cam profile used and the porting work!

Really enjoying following this thread, please keep it up!

Daniel.
 

howardsmed

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Sold ??.......... I gave it to him, and most of the spares too, that it why I am the ragged trousered Philanthropist.
The cam profile we used for the 880 I designed ( on the phone) with Ken Newman of Newman cams. it took 20 minutes,
so anyone who tells you there is a magic in cam design might be fibbing. OR which is unlikely in the extreme, I know what I am doing !
The actual machining work for the raised ports was done by Steve Mann, I have come up with what I believe will a be much quicker, and slightly improved method.
The raised port heads are one of two reasons the 880 goes so well, the other is the cam.
 

Bewarethemoon

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Ha ha ha! I stand corrected!

Back in the spring I spoke with Steve a little about this engine, he shared some information with me in regards to the modified intake angle.
I’m fascinated by the work being done here and excited to see more!

Will you be sharing your porting work or is it to secret/classified?

Daniel.
 

howardsmed

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YES....the port work will be available, Steve and I were thinking about doing heads some time next year, before that Rick and I need to section a head and work out if my modified method using thin wall seamless steel tube will work better than aluminium tube. I can machine an internal taper to the thin wall tube on our CNC lathe, which makes the "runner" more effective. One head design wont work for every engine. What we know is that lifting the port approach angle works, it might be a aggravation fitting it under a fuel tank though
The valve seat cut is all important and Steve has told you who to call. superb seats with total consistency is the way to go. ALL the important flow in a head occurs 1/2'' each side of the valve seat. Many years ago I worked for Carl Morrow building drag racing Harley engines in California, his head porting guy told me the same, he had worked for V&H and Russ Collins porting heads he was very clever. I came back to the UK, and did a set of heads for an 80CID Harley, I got +10hp more, and that was on an engine putting out 80hp rear wheel already. The heads took me an hour to do !!
The trick with all this engine work is getting the right ingredients, but that recipe must be sorted out at the beginning, not as you go along. One day I will write up some "combinations" that work. in the meantime anyone can call Rick Forte and have a 74hp 750 engine built, the exact same engine we raced last year.
 

gggGary

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The conventional wisdom, oft repeated, was that the crankcase behind the cylinders was only good for about 80-90 HP before racing stress would start cracking them. Any comments on that?
Thanks for this thread!
PS I like the emphasis on "street motor" power.
 
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howardsmed

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Hi Gary

In an internal combustion engine the torque that rotates the crank is generated from two sources. Two I hear you say, Yes. One is called instantaneous gas torque the other is inertial torque, the instantaneous gas torque is as described and is from the burning fuel air mixture, the other inertial torque is from the inertia of the pistons. This inertial torque is a function of piston/upper rod mass and rpm. Therefore it is easy to see that high rpm with heavy pistons causes high inertia loads. On a 360 degree twin these loads are multiplied by two, as there are two pistons. The forces in play are huge. These forces wreak absolute havoc with parts, on the engines we run which are all rephased to 277 degrees the inertial loads are reduced by nearly a 1/2, as one piston nearly cancels out the loads created by another

This is a slight oversimplification of the whole mechanics of it, but essentially that is why wee don't break cases. The figure of 84-90hp is not really conventional wisdom it is unfortunatly more idionet cobblers. The power ( torque x rpm) the engine creates has nothing to do with the stress, if the power created was quoted with an rpm figure, THEN it would make some sense, it is extremely high inertia loads which break the cases, gearboxes, con rods etc.

I have been told innumerable times how rephasing is "not required" or doesn't do anything. If that was the case, then every engineer ( by which i mean proper engineers with B/Eng Hons after their name) is wrong and only they are right. Every manufacturer that makes a parallel twin has gone the 270 degree route. Yamaha TDM, Triumph, etc, it is only because 277 is so easy we go that angle.

Yamaha knew from their racing on flat tracks that the crank-cases were weakest at the point near the top rear engine mount, they modified the mount ( internally) three times to strengthen it, which would suggest that even in stock 650 from they had the inclination of an inertia induced stress problem

However in all engine sizes and at very high rpm, we have not broken a single set of cases in six years. Our redline is set a 8300-8400rpm.

Colin Chapman often said racing improves the breed, and he could not be more right

All the things we have learnt from racing are applied to the road engines, I no longer run Smedspeed from day to day, I just design parts for the racing engines, and advise on how to build street engines with the broadest power band

hope this helps

Howard B/Eng ( Hons) Mechanical Engineering
 

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Revisiting this thread, did you ever get the chance to get back to the dyno, to give this motor another go? I know you thought there was more power to be had from it.
 

howardsmed

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When Steve sent me the dyno sheet he said that the power died completely at 7500rpm, it did, but it wasn't power drop off it was the throttle being shut. Richard Albans who runs TTS here in the UK, knew the engine was new, so treated it well. the power was definitely flattening at 7500rpm, i believe Steve did another run, and got 92 hp at 8000rpm ( approx.)
We knew all along that the engine would valve size limited, we were running 43mm valves, basically Yamaha XV750 size. The maximum size valve you can get on the stock seat is 44.8mm which is what G&S who make our valves had made before, many years ago for 1000cc sidecar moto cross bikes.
Steve Mann has since come into some ££££ so went and bought a BMW airhead 1100cc for racing ( traitor) but has still got the 880, he sold the 750 race engine which did 3 seasons without any parts replacement

i am sure in due course we will put bigger valves in, BUT that requires bigger seat IDs and that slows velocity, which will move the power up, good for racing, but not so good for street use.

I think, all things considered, that the 880 is the very best street engine you can build, it produces huge torque, and it doesn't need to rev past 7500rpm, so reliable etc. It does however need a 533 crank which is Europe only fitment , BUT there are 1000s of these around, it also needs the head bolt holes filled and then re-drilled along with a few other details.
 

gggGary

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My understanding was that Heiden got a bunch of "big bore" cylinders with the holes not drilled last spring for that reason. You know anything 'bout that?
 

howardsmed

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The casting ( VAM copy) that Jerry used to sell me had 8 x 10mm through holes, which is what we wanted to end up with, but still had the holes for the large dowels, on a really big bore we had stopped using the cylinder stud dowels, we plugged, welded, and then surface ground and then re-drilled to just 10mm, then we re-located the dowels to the holes that are under the spark plugs

the dowel we used is the one off the primary or alternator cover. we had gaskets specially made ( in the USA) to accommodate this move

the head pic below, you can see the hole enlarged under the outer two bolt holes for these dowels

i told Jerry what we had done, i believe
880 build ---- 001.JPG
he did the same thing too.
 

howardsmed

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Steve Mann recently sold the 880 engine, as the size puts him into the 1000cc bracket, and although the engine is 90hp, the BMW1000 airhead engines are over 100hp

he got £6500 for it, for a guy who is going to put it in a road bike
 
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