tts supercharger, JE pistons and compression ratio

[ratsidecar]

Hi, while my rocket engine is stripped down to have the TDSU bearings replaed and second gear and the detent mechanism replaced with updated parts from later rockets I guess this would also be a good opportunity to replace the pistons. I see that JE supply pistons for the rocket with either 10.5:1 or 11.7:1 compression ratio. I intend to have a TTS supercharger kit fitted to my bike by next year and see that the stage 3 kit they offer uses higher compression JE forged pistons.

I would like to know which pistons they use with that kit so I can have the correct ones already fitted to the bike to save some labour and time.

And on an otherwise standard motor apart from exhaust and filter upgrades I assume it would be wise to back off the ignition timing by 3 degrees or so through the rev range at larger throttle openings to avoid the risk of detonation as I will have to run the bike as is for a year or so till I can get the funds together for the supercharger.

 

[Tripps]

I would contact them and ask them.

 

[Claviger]

The 10.5s are the ones they use, but never a bad idea to double check with a phone call, he’s very receptive to phone discussion.

Regarding timing, pull up the 20228 map in tuneECU and compare the timing with the 20776 map. All roadsters are delivered with between 4 and 7 less degrees of timing above 10% throttle than their ancestors. The Roadsters do have more timing at low rpm low opening though (think emissions).

This is why I can get away with close to (1-2 degrees more) stock timing at greater than 13.5:1 using 92 octane.

 

[ratsidecar]

Thanks claviger, I will give them a ring. Thats interesting about the timing differences with the roadster. Its quite a big change

 

[BigNorm]

I thought a lower compression ratio was desirable for forced induction.

 

[Tripps]

It is. I have the Carpenter 240 kit, I think but not sure it's 10 1/2 to 1, he said my cams and valves were fine for a turbo, but he'd have to swap pistons.