hi guys i run tag restricted heavy with an arrow x3 with x30
im having a testing day tommorow and want to play around with exhaust length, what is the best way to do it, whats a good starting point and what does longer and shorter make the engine do, any help would be great guys!
Comments12
Hi John,
Get several lengths of exhaust flex, or 2 inch exhaust tube, in increments of about 3mm. Going shorter will improve top end performance at the expense of bottom end.
Going longer will improve bottom end at the expense of top end.
Try each piece to see how they go, working up and down from what you have now. With the X30, I would suggest about 12mm either side of the original in total for starters.
Not sure just how effective exhaust length changes are with that restrictor in there. Only testing will give you that answer.
Terry
A good starting point is that recommended by IAME which is 450mm from the flange on the header pipe to the first weld of the exhaust pipe. Increasing this distance gives more low down power & shortening gives more top end power. The length is varied by different lengths of flex. Only increase / decrease by 5mm at a time.
John, what track are you testing at? Different tracks will require a change of pipe length.
Hi Richard, Is this…
Hi Richard, Is this measurement from face of flange that bolts to engine or rear of flange. I have just got a restricted light x30 and find it is pulling 15500(sometimes 15600 which is strange as I thought they were limited to 15500) down straight but does not get out of hairpin/tight corners real good. Is over 15000 revs too much for the restricted x30 engine do you know? Thanks Jason Jason richard gagie said: A good starting point is that recommended by IAME which is 450mm from the flange on the header pipe to the first weld of the exhaust pipe. Increasing this distance gives more low down power & shortening gives more top end power. The length is varied by different lengths of flex. Only increase / decrease by 5mm at a time.
They will run to 16k+ but the timing changes and knocks power out of it to help limit the rpms. Track will dictate what pipe/gearing to run. Jason young said:
Hi Richard,
Is this measurement from face of flange that bolts to engine or rear of flange.
I have just got a restricted light x30 and find it is pulling 15500(sometimes 15600 which is strange as I thought they were limited to 15500) down straight but does not get out of hairpin/tight corners real good.
Is over 15000 revs too much for the restricted x30 engine do you know?
Thanks
Jason
Jason richard gagie said:
A good starting point is that recommended by IAME which is 450mm from the flange on the header pipe to the first weld of the exhaust pipe. Increasing this distance gives more low down power & shortening gives more top end power. The length is varied by different lengths of flex. Only increase / decrease by 5mm at a time.
In TAG R, the best starting point is 85mm flex (or solid) spacer in the exhaust and aim for around 14500rpm.
As the others have said, different tracks may require a slight tuning change for maximum performance, I doubt this would ever yield more than a couple of tenths. So until you are within 0.5sec of the leaders at your track I would concentrate on driving :)
Enjoy your x30 karting!
Jason,
The measurement is from the face of the flange that bolts onto the engine. I would not be worried with 15500+ provided the temp. didn't rise dramatically.
Richard
It will depend on the track you at racing at.
It also depends on the gearing. Some will have less teeth bigger flex or the other way round.
I race res Heavy in Vic and all the track I will pull more that 15000RPM at Pucka I do around 15700. It has a long Straight same at Oakliegh.
At smaller track like Gippsland and Rochester I will still be doing 15300 to 15500 maybe more.
But you need to see what low revs you are doing.
You just need to test to see whats best for you as we all have slightly different set ups.
I found at one track once I had the right gearing that 5mm made a big difference with the leanght of the exhaust
Thanks, temperature was on…
Thanks, temperature was on 50 degrees which seems to be normal. Jason Jason, The measurement is from the face of the flange that bolts onto the engine. I would not be worried with 15500+ provided the temp. didn't rise dramatically. Richard
I run restricted Super heavy and the guys run anywhere from the normal 65mm flex length to over 110mm flex length which Hayes runs around. Also depends on driver ability which show thru in this class. As said, some run small flex and throw teeth at it or run long flex and run less teeth at it. A lot of set up time involved. Personally, I prefer 90mm flex length, but dependent on track will go longer. As a side note: Pop off for the carb at higher than 13lb seems to bee the go, with extra on the high jet. Gives that extra kick on the straight.
Sorry to add confusion for you
kev
Thanks for that info Kevin…
Thanks for that info Kevin Jason Kevin Hitchcock said: I run restricted Super heavy and the guys run anywhere from the normal 65mm flex length to over 110mm flex length which Hayes runs around. Also depends on driver ability which show thru in this class. As said, some run small flex and throw teeth at it or run long flex and run less teeth at it. A lot of set up time involved. Personally, I prefer 90mm flex length, but dependent on track will go longer. As a side note: Pop off for the carb at higher than 13lb seems to bee the go, with extra on the high jet. Gives that extra kick on the straight. Sorry to add confusion for you kev
13lbs..........WOW !! Is that with a standard or drilled carb ? Curious to know.
Cheers AJ :)
Kevin Hitchcock said:
I run restricted Super heavy and the guys run anywhere from the normal 65mm flex length to over 110mm flex length which Hayes runs around. Also depends on driver ability which show thru in this class. As said, some run small flex and throw teeth at it or run long flex and run less teeth at it. A lot of set up time involved. Personally, I prefer 90mm flex length, but dependent on track will go longer. As a side note: Pop off for the carb at higher than 13lb seems to bee the go, with extra on the high jet. Gives that extra kick on the straight.
Sorry to add confusion for you
kev