Supercharged Bike engine
Discussion
Hi podman. We are about to test a boost control set up on a Procharger we have done. It would work by bleeding the inlet air off rather than bleeding exhaust gas. The problem with this is the noise it makes so I intend to bleed it into a custom made exhaust through a wastegate.
Not done it yet but my theory is there Here is our set up so far...
Its a good point regards throttle control on the chargers. However I would say as in my very first post that good turbocharger selection on a bike stops that being an issue. A correctly sized turbo can be as much a straight line on a dyno graph as a charger. The previous mistakes people made was to fit turbos that were too small.
Not done it yet but my theory is there Here is our set up so far...
Its a good point regards throttle control on the chargers. However I would say as in my very first post that good turbocharger selection on a bike stops that being an issue. A correctly sized turbo can be as much a straight line on a dyno graph as a charger. The previous mistakes people made was to fit turbos that were too small.
Big CC racing said:
However I would say as in my very first post that good turbocharger selection on a bike stops that being an issue. A correctly sized turbo can be as much a straight line on a dyno graph as a charger. The previous mistakes people made was to fit turbos that were too small.
I guess I'm not questioning the shape of the dyno curve, and not even lag, more the fact that on a small throttle adjustment mid bend or on the exit, power will vary depending on turbine speed and boost immediately available. I am in no way an expert like yourself, but have a science/engineering background and based on my humble knowledge I would have thought a smaller turbo would have given less power, but MORE consistent power on part throttle openings. Can you explain why too small turbo's would cause issues or are you talking about surge problems?Additionally - others have mentioned that exhaust gas is 'free' power with turbos - although I agree there is less overhead than supercharging, the volumetric efficiencies of turbo engines on the exhaust side 'strangles' the engine's breathing so not exactly 'free'. ie. a few initial psi are needed to regain the same power as the original NA engine to offset the greater back pressure and worse exhaust gas scavenging. (and that's before you even start with compression lowering).
To reiterate - I am pro-turbo for bikes, but not dismissive of some of their short comings in a track bike (non-drag racing) scenario which is the posters planned use.
Edited by 3doorPete on Wednesday 19th November 20:25
Edited by 3doorPete on Wednesday 19th November 20:28
the speed of boost build on a turbo bike is determined by the exhaust gas going through the turbine housing. The tighter that housing the more the gas spins the impeller therefore the faster the impeller spins so more air is also forced on the inlet side. Equally it will exhaust back pressure & can affect the cylinder scavenging & temps.
larger turbos will allow more gas to go around the impeller & thus not spin it so hard. these typically are good for peak power applications with a slower boost speed.
In the middle ground you will get a good all round unit. Not too laggy but not too fierce.
For example
The Mitsubishi turbo unit often used on many Busas will be like a 2 stroke power band spinning early & peak pwering at about 8500. 1 bar= 280bhp This turbo is flat out at 345bhp.
A GT30/71R roller bearing garett will create boost 500 to 1000rpm later take slightly longer to build to wastegate openeing but 1 bar = 340bhp & peak power is 450bhp.
A GT 35R roller bearing turbo will spool slightly slower still but 1 bar can be 360+bhp & peak power I have seen over 600 with the right engine combo.
However the hardest on any of these bikes to drive at say 300bhp is the mitsubishi. In drag racing it will wheelspin all the way up the track & on the road it will wheelie or step out the most on cornering. the larger turbos are using more sedately less boost for the same power level giving better control. For an experienced rider the mitsubishi may be the most fun though.
larger turbos will allow more gas to go around the impeller & thus not spin it so hard. these typically are good for peak power applications with a slower boost speed.
In the middle ground you will get a good all round unit. Not too laggy but not too fierce.
For example
The Mitsubishi turbo unit often used on many Busas will be like a 2 stroke power band spinning early & peak pwering at about 8500. 1 bar= 280bhp This turbo is flat out at 345bhp.
A GT30/71R roller bearing garett will create boost 500 to 1000rpm later take slightly longer to build to wastegate openeing but 1 bar = 340bhp & peak power is 450bhp.
A GT 35R roller bearing turbo will spool slightly slower still but 1 bar can be 360+bhp & peak power I have seen over 600 with the right engine combo.
However the hardest on any of these bikes to drive at say 300bhp is the mitsubishi. In drag racing it will wheelspin all the way up the track & on the road it will wheelie or step out the most on cornering. the larger turbos are using more sedately less boost for the same power level giving better control. For an experienced rider the mitsubishi may be the most fun though.
well!! five years down the line, i didnt get a forced induction engine and went for a NA duratec with 300bhp! its had three re-builds in 8 hours use and now i'm back looking at SC/TC engines again but more biased toward the turbo side, mainly due to using a bike engine and keeping the weight down.....having said that i have been offered a Big CC pro-charger by someone, so im back to square one! i sent Big CC and email the other day after a phone call with him (Sean) but have heard nothing back with regards to a breakdown in costs but 10 g is a figure that keeps popping up!
Anyway, garage to get built so it wont happen quickly, but ill post up my results which hopefully this time will be in physical form!
If anyone has any ideas or experience over the last few years on this subject i'd be interested to hear them.
Anyway, garage to get built so it wont happen quickly, but ill post up my results which hopefully this time will be in physical form!
If anyone has any ideas or experience over the last few years on this subject i'd be interested to hear them.
Have not read the entire thread , but today i rode my mates recently completed TTS Supercharged Triumph Speed triple .
I can confirm it was quite quick to say the least, but also very ridable at legal speeds .
Saw the dyno chart to prove the 199.7 rear wheel BHP .
Considering supercharging my 1090RR Brutale .
I can confirm it was quite quick to say the least, but also very ridable at legal speeds .
Saw the dyno chart to prove the 199.7 rear wheel BHP .
Considering supercharging my 1090RR Brutale .
steve1968 said:
Have not read the entire thread , but today i rode my mates recently completed TTS Supercharged Triumph Speed triple .
I can confirm it was quite quick to say the least, but also very ridable at legal speeds .
Saw the dyno chart to prove the 199.7 rear wheel BHP .
A 200bhp Speed Triple?! I can confirm it was quite quick to say the least, but also very ridable at legal speeds .
Saw the dyno chart to prove the 199.7 rear wheel BHP .
What was the power delivery like? A relentless surge of torque at all rpm? Did you ever need to change down from 6th gear?
It would seem to make more sense for beefing up the low-mid-range of a smaller bike engine, though, rather than something that is already fairly quick.
I built a Turbo busa engine for my old Westfield.
Was running about 1bar of boost at circa 300BHP.
Power delivery was great, if you have a few revs showing on the tacho it just felt like a big engine.
I looked at the supercharger route and went turbo.
As some people have said it will cost 3 times as much as you think !!!
Was running about 1bar of boost at circa 300BHP.
Power delivery was great, if you have a few revs showing on the tacho it just felt like a big engine.
I looked at the supercharger route and went turbo.
As some people have said it will cost 3 times as much as you think !!!
bazzeruk said:
I built a Turbo busa engine for my old Westfield.
Was running about 1bar of boost at circa 300BHP.
Power delivery was great, if you have a few revs showing on the tacho it just felt like a big engine.
I looked at the supercharger route and went turbo.
As some people have said it will cost 3 times as much as you think !!!
That seems to be the case, turbo lag being minimal, i dont think it will be an issue. Just gagging to get started!!Was running about 1bar of boost at circa 300BHP.
Power delivery was great, if you have a few revs showing on the tacho it just felt like a big engine.
I looked at the supercharger route and went turbo.
As some people have said it will cost 3 times as much as you think !!!
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