The Gran Turismo big block conundrum
make it LC .. you know you want to
Its in bits scooter club: www.facebook.com/groups/132415046859320
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Rich_T
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For Avatone etc.
Is there demand for a blank cylinder only?
In short no; really do not under estimate how hard and costly it is to machine an iron barrel accurately. A good reputation is based on consistency of quality and good design. It is therefore critical to know that all product is correctly machined. This also gives confidence to an after-market that products are equal and not money pits with expensive vices to sort out (remember the alloy BMW straight 6 problems?).
* Big fin:
A good, commendable and ballsy approach from RM. It does go against the GT design brief of stock appearance so it is not one that I will follow.
* Un-machined top and tail to allow latitude between 58 & 62 stroke whilst still giving options on timings once ported:
A definite NO NO, the first CNC op is to define datum points and this is from the Bore, skirt & base gasket face which is then the reference for all other faces and operation. The standard barrel will accommodate 58 and 60 stroke with no modifications. 62 throws the port timings a bit too much, if you want it then a packer is required. This represents a tiny portion, in over 500 barrels I have only ever received 2 requests for this and both settled on packers or 60 stroke.
* Bridged exhaust but not opened up to give flexibility on duration and TA once stroke is decided:
Most certainly! The new exhaust ports are bridged, they are cast at 172 degrees and they go up to 90% of bore
* Transfers to match standard cutouts but sufficient meat to open up if cases welded:
Like GT186 they are actually larger than the case cut outs (easier to remove alloy than iron). Only very minor fettling and cleaning is required, port wall thickness is 5mm clearance to studs is 2mm you don’t really want less than that and in a production environment is very hard to achieve less without a very high reject rates (which have to be recovered somewhere, like unit price).
* Options and pricing structure ranging from blank cylinder through to fully finished 240:
Production runs are 40pcs min, it is not commercially possible to break up the machining run to lots of different options (hence this thread).
* Options to supply reed, manifold, head, fully machining and finishing:
Only one option for kit and this is fully machined. This is THE ONLY WAY to control quality and variables. Kit has choice of manifold sizes and head or no head, that will be it. Remember that the kit is highly flexible as standard so just by following the manual and bolting on different bits a standard GT186 has about 8 different configurations of manifold, pipe and stroke (when the Big Block arrives there will be another two manifolds so this will go up to 32 without a die grinder in site).
Something on every price point, and options to wholesale too:
It has to be kept really simple, so it will be one price for the kit (including a manifold choice) and one price for the head.
A better inlet solution that filters through a proper (though not original) air box, and doesn't involve a rubber tube with a 90 degree bend in it:
Oh yes, with you on that one and they are at the machine shop now. Pictures will be posted when they’re done. CNC machined and laser cut with large KTM foam filters.
Sticky, Corrado, I’m with you:
Starting at 66 with 20 odd over-sizes, that’s a life time of riding. On the 200 block stud spacing the ports will be much wider so there should be a good increase in performance over the 66 bore small blocks and the same reliability (GT186’s already do 70 so a big block should do that will a bit less stress). It is looking like the majority are after “bang for buck†with a reliably long service life which is the 200cc route. Perhaps as more are produced I can divert some funds into special Mataka pistons, we’ll have to see how it goes (Mataka are economic but you have to buy serious quantity, its swings and round-abouts).
A laser cut aluminium packer is all that would be required for a TV rod conversion and that is a simple do-able extra.
Numerous people have said that they don’t want to be “shoe horned†into buying pipes, ignitions and carbs with the kit. This is principally down to overall costs, they may have some parts that are suitable already or they are intelligent enough to just pain want to experiment. The plan (as is currently the case) is to make a recommendation in the build manual and keep some parts stock but not to shackle the owner into a single source option.
Is there demand for a blank cylinder only?
In short no; really do not under estimate how hard and costly it is to machine an iron barrel accurately. A good reputation is based on consistency of quality and good design. It is therefore critical to know that all product is correctly machined. This also gives confidence to an after-market that products are equal and not money pits with expensive vices to sort out (remember the alloy BMW straight 6 problems?).
* Big fin:
A good, commendable and ballsy approach from RM. It does go against the GT design brief of stock appearance so it is not one that I will follow.
* Un-machined top and tail to allow latitude between 58 & 62 stroke whilst still giving options on timings once ported:
A definite NO NO, the first CNC op is to define datum points and this is from the Bore, skirt & base gasket face which is then the reference for all other faces and operation. The standard barrel will accommodate 58 and 60 stroke with no modifications. 62 throws the port timings a bit too much, if you want it then a packer is required. This represents a tiny portion, in over 500 barrels I have only ever received 2 requests for this and both settled on packers or 60 stroke.
* Bridged exhaust but not opened up to give flexibility on duration and TA once stroke is decided:
Most certainly! The new exhaust ports are bridged, they are cast at 172 degrees and they go up to 90% of bore
* Transfers to match standard cutouts but sufficient meat to open up if cases welded:
Like GT186 they are actually larger than the case cut outs (easier to remove alloy than iron). Only very minor fettling and cleaning is required, port wall thickness is 5mm clearance to studs is 2mm you don’t really want less than that and in a production environment is very hard to achieve less without a very high reject rates (which have to be recovered somewhere, like unit price).
* Options and pricing structure ranging from blank cylinder through to fully finished 240:
Production runs are 40pcs min, it is not commercially possible to break up the machining run to lots of different options (hence this thread).
* Options to supply reed, manifold, head, fully machining and finishing:
Only one option for kit and this is fully machined. This is THE ONLY WAY to control quality and variables. Kit has choice of manifold sizes and head or no head, that will be it. Remember that the kit is highly flexible as standard so just by following the manual and bolting on different bits a standard GT186 has about 8 different configurations of manifold, pipe and stroke (when the Big Block arrives there will be another two manifolds so this will go up to 32 without a die grinder in site).
Something on every price point, and options to wholesale too:
It has to be kept really simple, so it will be one price for the kit (including a manifold choice) and one price for the head.
A better inlet solution that filters through a proper (though not original) air box, and doesn't involve a rubber tube with a 90 degree bend in it:
Oh yes, with you on that one and they are at the machine shop now. Pictures will be posted when they’re done. CNC machined and laser cut with large KTM foam filters.
Sticky, Corrado, I’m with you:
Starting at 66 with 20 odd over-sizes, that’s a life time of riding. On the 200 block stud spacing the ports will be much wider so there should be a good increase in performance over the 66 bore small blocks and the same reliability (GT186’s already do 70 so a big block should do that will a bit less stress). It is looking like the majority are after “bang for buck†with a reliably long service life which is the 200cc route. Perhaps as more are produced I can divert some funds into special Mataka pistons, we’ll have to see how it goes (Mataka are economic but you have to buy serious quantity, its swings and round-abouts).
A laser cut aluminium packer is all that would be required for a TV rod conversion and that is a simple do-able extra.
Numerous people have said that they don’t want to be “shoe horned†into buying pipes, ignitions and carbs with the kit. This is principally down to overall costs, they may have some parts that are suitable already or they are intelligent enough to just pain want to experiment. The plan (as is currently the case) is to make a recommendation in the build manual and keep some parts stock but not to shackle the owner into a single source option.
Rich,
Does the exhaust port point backwards a tad like the RB kits?
Irrelevant of the answer above, would there be any benefit in designing a preferred exhaust system with it? One that you can licence out to be made elsewhere (ala Franspeed, NK etc etc), allowing you to profit slightly from the sale of each one .... cash that could go towards other improvements / ideas etc . I know theres alot of exhausts out there but none made specifically for your new intended kit yet?
Does the exhaust port point backwards a tad like the RB kits?
Irrelevant of the answer above, would there be any benefit in designing a preferred exhaust system with it? One that you can licence out to be made elsewhere (ala Franspeed, NK etc etc), allowing you to profit slightly from the sale of each one .... cash that could go towards other improvements / ideas etc . I know theres alot of exhausts out there but none made specifically for your new intended kit yet?
Hi Rich, yes please, put me down for a 200 one, fancied a GT186 for a wile but haen't got a suitable small case for one, our mutual mate Dez is working on something for me now, no top end on at the moment, and a GT200 may fit the bill nicely for all the reasons already mentioned, reliability, good high and touring speeds, economical, standard looks, good torque and my case has a standard TV200 box fitted, do you want a tester for a prototype?
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corrado
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That's where I was coming from Ian with my thoughts on exhaust, crank and carb kit.soullad wrote:Rich,
...... would there be any benefit in designing a preferred exhaust system with it? One that you can licence out to be made elsewhere (ala Franspeed, NK etc etc), allowing you to profit slightly from the sale of each one .... cash that could go towards other improvements / ideas etc . I know theres alot of exhausts out there but none made specifically for your new intended kit yet?
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Train Driver
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A quiet clubman exhaust, a small filtered carb, 70 mph all day at standard revs would make me happy.
plus oil injection please :freak: :freak:
Oh and 225cc
plus oil injection please :freak: :freak:
Oh and 225cc
TS1 and PX stay in the garage (future barn finds) out on the GTS 300 when I go out on a scooter.
I know I’ll get there and back
I know I’ll get there and back