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Draw through: distance carb to turbo?


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Thanks guys, usefull info here!


Will check in to adapting the HSR 45 Zepp, my mate can CNC whatever I need so a new floatbowl with different fittings is no bother.


Yes the yellow was fucking terrible...!!!


I really should take some recent pictures and post them, will do so when the last bits are back from the painters!


Meanwhile I've changed the complete exhaust!!!


I kept to the design of GJG as far as the headers go only now I went from 28 mm internals to 30mm internals into a 60mm collector instead of 35 mm.


Also I've complete changed the linkpipe to the turbo: from a weedy 30mm to 60mm and with an exact fit to the turbo rather than a 30mm round hole blowing into a suare hole that's about twice the size...


First impressions without riding it: runs smoother at idle and revs quicker so off to the dyno next!

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Don't want to piss on your parade but as far as i know the bigger the pipes the lower the gasspeed wich can result in even slower spool up.

Probably smaller turbine wheel and housing wil have bigger effect in faster spool up.

increasing pipe sizes can result in higher bhp output but i think that wil only work if you do really big numbers .

correct me if am wrong


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Yes, the smaller the diameter the higher the gasspeed, this much is true.


However, gasspeed doesn't really tell the whole story:


Due to the small diameter the engine can't breathe properly, it can't push out the exhaustgas fast enough which is affecting several things such as the burn inside the chamber, the heat of the engine and also spool up because now there's no restriction and more gasvolume to help spool up.


Mind you, spool up isn't bad anyway.

With this exhaust it idles easier, runs leaner at idle and it revs quicker so I don't think it'll be all that bad...a 1216 cc engine putting out 285 BHP on such a small exhaust is pretty good but imagine what a restirction the exhaust must be on this engine!

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  • 4 years later...

I am having the same problem with ss super e draw through, rajay turbo. Small tire gs 1168 dragbike running on street . If I takes off the air filter it runs fairly smooth till cruising at highway speed then it stumbles , big bog if you do not roll on throttle just right. Put the air filter on then the bog issue is  much better but at lower speed cruising it runs rough. I am wondering is hs 42 would improve things or if  I built an air box ?

Only running 7 pounds boost for now, and back when it raced we ran pump gas and 12 pounds boost about 190 hp.

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  • 3 weeks later...

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