SupraTT Posted January 21, 2002 Share Posted January 21, 2002 Everyone says that as a rule of thumb, you shouldnt "ideally" run more than 1.2 Bar Boost on a J-Spec because of the dangers of the Turbo blades breaking, being made of Ceramic as opposed to UK Spec steel. What i want to know is has anyone actually had this happen or what views do you have on this ? What boost is everyone running their J-Spec with Stock Turbos at ? Michael Quote Link to comment Share on other sites More sharing options...
Alex Posted January 21, 2002 Share Posted January 21, 2002 Max 1.2bar normally 1.05bar....nowt broken yet. But I believe you are mising 1 point which is covered in the Compressor maps thread which is that turbo's have an efficiency range. 1.2 bar is IMO the limit of the j-spec efficiency range after which you apparently get limited benefit and can reduce the reliability hand over fist. So why bother exceeding the edge of the efficiency range when it could leave you with a nasty bill for new parts. Hybrids usually have a higher efficiency range go for them if you wish to boost higher - though the change of t's should be enough to satisfy you for a while. Having said that some members of this BBS say they run 1.4bar on ceramics and have no probs to date. If you wish to go high boost please make sure you fit either an FMIC or an ERL aquamist system. Quote Link to comment Share on other sites More sharing options...
Guest Martin F Posted January 21, 2002 Share Posted January 21, 2002 As far as i am aware the biggest failure on ceramic bladed turbo's is not the blades cracking, but the turbine and compressor wheels coming off the shaft. Because they are ceramic the only way to attach them is to glue them to the shaft. As you increase boost the wheels spin quicker and in turn stress the adhesive further. Quote Link to comment Share on other sites More sharing options...
Paul Whiffin Posted January 21, 2002 Share Posted January 21, 2002 I run 18/19 psi but have seen 22 psi on my std Jap turbo's. No problemos to date, been like that for about 16,000 miles now. Quote Link to comment Share on other sites More sharing options...
Branners Posted January 22, 2002 Share Posted January 22, 2002 Same with me, I run up to 1.45kg on my stock turbos and they havent flung themselves out the exhaust YET. But they are operating outside their efficiency maps at that point. I know of about 5 cars that have blown their ceramic turbos, Lee Burley was one of the first and both his first and second turbo went and it basically stripped the blades clean off the shaft. Since then I have seen various turbo internals which have had the majority of the blades ripped off. So it can happen but just view it as an opportunity to upgrade to hybrids...I know I am. JB Quote Link to comment Share on other sites More sharing options...
Flipfinger Posted January 22, 2002 Share Posted January 22, 2002 I believe Glenn Warren found his Supra (before the gold paint job) had a fair number of propeller blades of the turbos had come off and flown out of the exhaust.... Quote Link to comment Share on other sites More sharing options...
Graham Rudd Posted January 22, 2002 Share Posted January 22, 2002 Yep, my stock turbos disintegrated running 1.25 bar. I think my front cat still might have bits of the little buggers rattling about inside it. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted January 22, 2002 Share Posted January 22, 2002 Quote: from Graham Rudd on 9:26 pm on Jan. 22, 2002[br]Yep, my stock turbos disintegrated running 1.25 bar. I think my front cat still might have bits of the little buggers rattling about inside it. Doubtful, when they go they turn to virtual dust (speaking ceramic here, and although *you* probably know, many people think that the compressor wheel and the turbine wheel are *both* ceramic, they aren't, only the turbine (exhaust side) wheel is ceramic, the centrifugal forces are apparently too great to run ceramics on the much larger diameter compressor wheel. To the original poster, they don't usually crack, as in "Oh look, there are cracks in my turbine wheel blades", they just let go catastrophically, one broken blade usually lunching the rest and leaving a smooth "blob" on the end of the shaft, or the whole friction welded wheel comes off and disintegrates. Quote Link to comment Share on other sites More sharing options...
Guest Martin F Posted January 22, 2002 Share Posted January 22, 2002 Quote: from Chris Wilson on 11:22 pm on Jan. 22, 2002[br or the whole friction welded wheel comes off and disintegrates. Errr friction welded ?? What's that then ? Not adhesive ? Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted January 22, 2002 Share Posted January 22, 2002 Quote: from Martin F on 11:31 pm on Jan. 22, 2002[br]Quote: from Chris Wilson on 11:22 pm on Jan. 22, 2002[br or the whole friction welded wheel comes off and disintegrates. Errr friction welded ?? What's that then ? Not adhesive ? As far as i have have always believed they are friction welded on, the "nut" is a dummy and there to give some mass for balancing purposes, if you look carefully they usually have flats ground on the nut to remove material to give a near perfect balance. Friction welding is where the two materials are spun together at very very high speed whilst also pressing them together. Bit like a maniac rubbing a stick in a cleft in a rock to get it glowing. Most production engine valves have the head friction welded to the stem for cost purposes, race valves are nearly always one piece and very expensive, less risk of them coming "un friction welded" :-) Quote Link to comment Share on other sites More sharing options...
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