Hi guys,
I'm buildng a GT206 engine for my series 1 at the moment. The engine is pretty much all built except for some fettling with the barrel and piston
I was looking at it last night and was thinking about some more porting to the top end, but I want to get some other opinions first!
The windows in the piston are much larger than the inlet port (which is the same width as a TS1 port)
I was thinking about making the inlet port wider to match the piston holes - would this be too big? My thinking is the suzuki this came out of had an inlet this big so whats stopping my inlet matching it?
Also, I was thinking about making the holes in the piston larger towards the middle and lower - would this help much?
Dryballs
GT kit - should I?
It might give you more power and it might give you a lot more power than you thought... But if you don't try it first as it is, how will you know if you have improved it.... Its not hard to run it as it is first... and then add your modifications later... Then you will know what the standard kit can do and then what effect your input has made to the power delivery...
I had a 186 GT kit with Taffspeed pipe and it pulled like a train without any mods.
Pulled up Poole Bank (a really big hill!!) and left the TS chaps asking a lot of questions when we reached the boozer!
Pulled up Poole Bank (a really big hill!!) and left the TS chaps asking a lot of questions when we reached the boozer!
i was thinking of one of these but what would be the comparison eg running in bhp compared to an imola, afterall is there that much in it ££?
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Rich_T
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DO NOT MAKE THE MODIFICATION YOU SUGGEST! The width of the inlet port is pretty much the maximum achievable between the barrel studs. The wall thickness on the iron at this point is about 1.5mm and this does not allow for any imperfections or inclusions hidden in the cast. One false move with the die grinder and you have a serious airleak that is a right pain in the backside to fix.
At best, polish the surfaces but do not get into cutting around with any of the areas.
Likewise, the piston is a highly stressed component, removing anything has to be very VERY carefully considered and the central web on thepiston most certainly should not be touched. If you want to mod the piston permisable changes would be to shorten the skirt by 2mm, a generous radius from the transition of the transfer windows to the skirt and a light polish if the interior or the piston. This will result in a slight reduction in weight without significant loss of strength.
I suggest if you want to look at modifications or improvements check over the manual first. This will give you a good guide for general specification to head for. for example there is absolutely no advantage in doing any of this if you run with a clubman, PHBL25 and un-matched casings.
For the barrel, a light cleaning of the surfaces with emery is handy (and looks good) but the best improvements come from lifting the exhaust timing by 0.8 - 1mm-ish if you want to run with an expansion pipe, this is highly advisable. Matching the casing to the transfers and optimising the head geometry/volume/squish etc and carb jetting, all the bits which it is very hard to cover in a production item. If you are cute you could widen the boost port windows by 1mm on the outside edges but do not narrow or remove the central web of the boost port.
Mail me directly if you like, I'm here to help and my knowledge and experience with this kit is about as good as it gets.
At best, polish the surfaces but do not get into cutting around with any of the areas.
Likewise, the piston is a highly stressed component, removing anything has to be very VERY carefully considered and the central web on thepiston most certainly should not be touched. If you want to mod the piston permisable changes would be to shorten the skirt by 2mm, a generous radius from the transition of the transfer windows to the skirt and a light polish if the interior or the piston. This will result in a slight reduction in weight without significant loss of strength.
I suggest if you want to look at modifications or improvements check over the manual first. This will give you a good guide for general specification to head for. for example there is absolutely no advantage in doing any of this if you run with a clubman, PHBL25 and un-matched casings.
For the barrel, a light cleaning of the surfaces with emery is handy (and looks good) but the best improvements come from lifting the exhaust timing by 0.8 - 1mm-ish if you want to run with an expansion pipe, this is highly advisable. Matching the casing to the transfers and optimising the head geometry/volume/squish etc and carb jetting, all the bits which it is very hard to cover in a production item. If you are cute you could widen the boost port windows by 1mm on the outside edges but do not narrow or remove the central web of the boost port.
Mail me directly if you like, I'm here to help and my knowledge and experience with this kit is about as good as it gets.
^^^ Input like this is what this forum is about^^^
I have a question - how is it that Dryballs' looks impact on the porting of the engine? Does this always hold true? Can good looking people really get away with more extreme porting?Rich_T wrote:If you are cute you could widen the boost port windows by 1mm on the outside edges...