supraspeed Posted January 19, 2009 Share Posted January 19, 2009 Ok has anyone ever used a smaller turbo with a big single? just i was thinking as many people with singles have problems with lag, is it possible to do a sequential system so that you get a boost at low revs from the small one, then a massive surge of power from the large one up the rev range? obviously finding a small turbo that can deal with the power or a system that shuts off that turbo once the larger one kicks in. just a thought Quote Link to comment Share on other sites More sharing options...
supradibbs Posted January 19, 2009 Share Posted January 19, 2009 Sound performance make a sequential turbo setup Quote Link to comment Share on other sites More sharing options...
j_jza80 Posted January 19, 2009 Share Posted January 19, 2009 Do you mean replace the complicated restrictive stock sequential system with another complicated and restrictive sequential system? Quote Link to comment Share on other sites More sharing options...
mustang Posted January 19, 2009 Share Posted January 19, 2009 (edited) As I understand it the stock turbos are the same size, and any other twin setup would have to be two the same. The larger turbo would force air backwards through the smaller one knackering it, and probably the engine too. Sorry, you've said that though, would mid sized twins not be better, would give a pretty smooth power increase through the revs. Edited January 19, 2009 by mustang (see edit history) Quote Link to comment Share on other sites More sharing options...
Kranz Posted January 19, 2009 Share Posted January 19, 2009 The control system for a compound turbo system with unequal turbos would be a nightmare. The small turbo would have to be first in line, then go through the big turbo. Problem comes whrn the big turbo comes on line and the small turbo is fed masses of exhaust gas that causes it to overspeed. The small turbo would have to be bypassed to allow the big turbo to take over. Quote Link to comment Share on other sites More sharing options...
supraspeed Posted January 19, 2009 Author Share Posted January 19, 2009 maybee 2 larger twins but not sure it would have more or less the same output as a well set up bpu but with more lag or a less laggy big single with less power. sounds like an interesting idea but prob not worth the hassle or money Quote Link to comment Share on other sites More sharing options...
miko_supra Posted January 19, 2009 Share Posted January 19, 2009 maybee 2 larger twins but not sure it would have more or less the same output as a well set up bpu but with more lag or a less laggy big single with less power. sounds like an interesting idea but prob not worth the hassle or money Probably worth the hassle more than a twin engine supra though Quote Link to comment Share on other sites More sharing options...
DAT Inter Posted January 19, 2009 Share Posted January 19, 2009 Just wouldnt work tbh. Quote Link to comment Share on other sites More sharing options...
imi Posted January 19, 2009 Share Posted January 19, 2009 Ok has anyone ever used a smaller turbo with a big single? just i was thinking as many people with singles have problems with lag, is it possible to do a sequential system so that you get a boost at low revs from the small one, then a massive surge of power from the large one up the rev range? obviously finding a small turbo that can deal with the power or a system that shuts off that turbo once the larger one kicks in. just a thought If you do some research you will realise that a street single setup can have pretty much zero (or like stock) lag; you talk about power, is 500-550 enough for you? if so, then I really dont see the point of your post. Quote Link to comment Share on other sites More sharing options...
Ian C Posted January 20, 2009 Share Posted January 20, 2009 The BMW sequential setup on the 335d uses a small turbo then a big one and is a masterpiece of packaging and simplicity. The cost of this though is: A) quite an inefficient design. There will be a lot of pressure losses as one of the turbos is always drawing or pushing air through the other, depending on which is being used. Also, there are a lot of bends and restrictions in the system. However at boost pressure and power levels required for OEM all that is acceptable for the packaging and simplicity issues. B) Expensive - if either turbo goes, it'll take the other with it, and the price of a pair of them is north of £3000 - and that's mass production costs So while it can be done, it's not going to be economic to do, packaging will be troublesome, and if you get it all small enough it'll be inefficient for the desired power levels and cost a fortune due to the bespoke housings and castings required. Oh and I know all that because after a service my mates' 335d ingested its own #1 air hose gasket and lunched both turbos Nasty bit of design that. -Ian Quote Link to comment Share on other sites More sharing options...
Nick Posted January 20, 2009 Share Posted January 20, 2009 I remember a pair of couple of Aussies did this, but that was a couple of years ago and I've lost the link. Complicated setup too, took a lot of work. Quote Link to comment Share on other sites More sharing options...
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