sip long stroke t5 crank

[soulboy]

as anybody used one ??? im looking in to it want to no is there a lot of power gain over a cut and polished stock crank on a 172 cheers

[cezeta]

take a look at this engine by diablo in the vespa dyno section http://i137.photobucket.com/albums/q217 ... oT5170.jpg

[OzOAP]

Hopefully Tony can help, or send him a PM.
Ive never had any dealings with one, but in the T5/TS1 thread, he says long stroke T5 is the much better option.

[soulboy]

i take it it fits without any mods needed bar the packing plate

[cezeta]

Hopefully Tony can help, or send him a PM.
Ive never had any dealings with one, but in the T5/TS1 thread, he says long stroke T5 is the much better option.

i spoke to tony about this and he was very enthusiastic about it. beyond my know how but i like the idea of it as the 172 alone is just a bit lacking

[tony]

I have never done a large frame t5 long stroke but my road bike ran a 54 stroke on a smallie casing with a t5 barrel.
The German lads are stroking this motor and for sure offset pins are available possibly even cranks now. I know worb 5 did one. Dunno if the sip one is this.
Another idea is to modify a t5 crank if there is enough metal. It's been years since I saw one. Not sure on the differences with the t5 to px now.. It's been too long ago.
Anyway. Going back the t5 motor when kitted is very over square and I am certain the malossi transfers were very low which kind of lends itself to a longer stroke

[cezeta]

so tony for us basic spanner monkeys/none tuning types do you think a long stroke crank onto a 172 kit with no other work other than packers would work?

[tony]

if someone can get me the port heights of a malossi barrel i will run it through pooter and see whats what. But yes I do think it has a lot of potential.. after all lauro caforio himself is building a whole new motor based around the T5 barrel/stud config which will be an off the shelf casing to buy.

[tony]

had a look at sck

main and secondaries are 42
ex is 30.5
rod 105
stroke 52
On a deck of 0 (to keep it simple) trans are 116.71 and ex 174.54 with blowdown of 28.92

with a stroke of 56.5 and 110 rod , trans shoot up to 135.98 at the same deck with 185.8 ex.
Thats a little lary on the trans for road use as I know how Nick Cezeta likes em... so dropping it down 1.5mm brings the trans down to 128.53 or at 1.75 the trans will be at 127.26.. Maybe still to high for some... but the blowdown is low by now so some ex port work needed. The head will need work or a head gasket, or material added to the barrel (which is what I would do). But its all there really.

I wonder what Darrel makes of this thread. His input would be good.

[Darrell Taylor]

looks like the t5 has a pretty good set up to start with and the std cylinder is a great kit ,if it can be stroked and durations retained and port widths etc reworked where neccessary then the operating range should be ideally suited to the gearbox basically a bigger brother tune ,call it a T6
as tony says the transfers are running away forcing a raise in ex dur to retain the blowdown but at circa 186 it will start to run away from the gear ratios forcing the use of a longer pipe to get it onto pipe in a similar rpm range to std ,unless there are nice gearbox options of which i wouldnt know,i suppose intended use is whats needed to be known tour/fast road/race/sprint and the pipe lengths that its to be used with and reverse calc back

or increase blowdown by adding 2 aux ex ports and keep duration low , leave the pipe short and make use of the high transfer to cover the higher operating rpm transfer requirements ,gear for better accelleration to aid the gaps between ratio,s as the extended rpm range will now give u 10mph more top speed u can afford to lose 5mph of top end gearing and still be 5mph up on before,downside is cruising speed will be 5mph higher (but cool the motor better with increased fan speed)
many ways to skin the cat