Guest Terry S Posted June 20, 2003 Share Posted June 20, 2003 I was speaking yesterday to an owner who recently got a car with big twins. The car has no BOV. The tuner, who will remain nameless, told him he didn't need a BOV as he had an external wastegate. Thoughts on a postcard please guys............... Quote Link to comment Share on other sites More sharing options...
Guest Martin F Posted June 20, 2003 Share Posted June 20, 2003 *Boom, Boom, shake the room* Quote Link to comment Share on other sites More sharing options...
Guest Terry S Posted June 20, 2003 Share Posted June 20, 2003 LOL I am thinking of starting a sweep stake on the longevity of the turbo's. Gentlemen, may I start the bidding at 1k miles Quote Link to comment Share on other sites More sharing options...
Wez Posted June 20, 2003 Share Posted June 20, 2003 No BOV = Nice turbo churps between gear changes and on let off. Ok if you want to have antilag but not good unless turbos designed to take the bashing Do we know what turbos they are? I am just gonna lay low now as I am sure there will be some bun throwing :flame Dev Quote Link to comment Share on other sites More sharing options...
Adam W Posted June 20, 2003 Share Posted June 20, 2003 I have heard in the past that some tuners don't bother to fit BOV's on big turbo installations, I have also heard that Garrett themselves have a fleet of cars which they've turbocharged and very few of them have BOV's fitted. All second or third hand info but perhaps they are not quite as important as everyone makes out? I dunno but I won't be taking mine of anytime soon Getting BOV function confused with wastegate function is a schoolboy error, hope the tuner wasn't anyone that club members use. How do these people make a living when they are so utterly incompetent at their jobs? Quote Link to comment Share on other sites More sharing options...
Wez Posted June 20, 2003 Share Posted June 20, 2003 Hey Adam, I agree, a decent turbo should function normally without a BOV and I know of a few cars which do not use them, one is my old car and a couple of tuned scoobys. Mind you they are running antilag Agreed that the life of the turbo would also be affected but that would depend on the turbo, not a good idea on the cyramics :flame Dev Quote Link to comment Share on other sites More sharing options...
Guest Terry S Posted June 20, 2003 Share Posted June 20, 2003 Do you guys not think compressor surge may be a bit of a problem? OK so you are driving down the road at 1.3 bar & you lift off the throttle, so it slams shut. Where does all that pressure go? Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted June 20, 2003 Share Posted June 20, 2003 Originally posted by Terry S Do you guys not think compressor surge may be a bit of a problem? Sometimes they will hit surge, depends on a huge array of variables, but BOV's were really "!invented" for noise issues when turbos were fitted to passenger cars, I can think of no serious race engine apps where a BOV is used unless it was "there" in the road car application it may have been based on. F1 turbos, Indy cars, blah blah never used a BOV, and they were pretty interested in reliability and rapid spool up. Quote Link to comment Share on other sites More sharing options...
Adam W Posted June 20, 2003 Share Posted June 20, 2003 I'm sure you know more about this than I do but isn't compressor surge when a large compressor wheel is matched with a too-small exhaust a/r, so at light throttle/loads the turbo is producing more air than the engine can ingest and you get pressure reversals in the intake tract . . . I'm not 100% but that's my understanding of it. I know I've read a few posts on supraforums that give me the impression that compressor surge is nothing to do with BOV's, not to say that they're right of course! I know you'll get backpressure against the comp wheel when you lift off, but I guess that these guys don't think that is a big deal. Quote Link to comment Share on other sites More sharing options...
Guest Terry S Posted June 20, 2003 Share Posted June 20, 2003 Sorry Chris but if they were invented purely for noise then why did toyota put one on the supra then silence it with the stock air box? I have no doubt that they are not essential in race cars, but road cars! Quote Link to comment Share on other sites More sharing options...
Wez Posted June 20, 2003 Share Posted June 20, 2003 Compressor surge is air flowing the wrong way, a number of things could cause it. Quote Link to comment Share on other sites More sharing options...
Guest Terry S Posted June 20, 2003 Share Posted June 20, 2003 Adam you do get comp surge from a mismatched turbo, but the BOV if set & positioned correctly will help alleviate it. I should re-phrase my earlier post as a BOV alone will not cure compressor surge if the turbo is badly mismatched Quote Link to comment Share on other sites More sharing options...
Ian C Posted June 20, 2003 Share Posted June 20, 2003 Whether a big turbo setup needs a BOV or not is besides the point, the tuner's reason for not having one is because it's got an external wastegate!?! That's the scary bit in my book. -Ian Quote Link to comment Share on other sites More sharing options...
Wez Posted June 20, 2003 Share Posted June 20, 2003 Well said Ian Quote Link to comment Share on other sites More sharing options...
Guest Terry S Posted June 20, 2003 Share Posted June 20, 2003 Oh Mr Chisholm you are so wise. That was the original point of the post;) Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted June 20, 2003 Share Posted June 20, 2003 Originally posted by Terry S Sorry Chris but if they were invented purely for noise then why did toyota put one on the supra then silence it with the stock air box? I have no doubt that they are not essential in race cars, but road cars! No, I meant that were "invented" to reduce the noise of the blades going into surge, not to make silly whooshing noises Quote Link to comment Share on other sites More sharing options...
Guest Terry S Posted June 20, 2003 Share Posted June 20, 2003 LOL sorry Chris;) Quote Link to comment Share on other sites More sharing options...
Nathan Posted June 20, 2003 Share Posted June 20, 2003 Originally posted by Ian C Whether a big turbo setup needs a BOV or not is besides the point, the tuner's reason for not having one is because it's got an external wastegate!?! That's the scary bit in my book. -Ian Indeed. As a trader, and in general respect for other traders I usually log any indifferences with a simple 'I disagree' but the fact that someone is bolting together big twin conversions and coming up with quotes like the above simply horrifies me. If the quotes are true then the level of incompetance shown is staggering. Tell me this is a wind-up? Regards, Nathan TDI PLC PS. FWIW, when it comes to BOV's I tend to think along the lines of 'why not use one'. Big twins or singles at 1.4bar+ shift massive amounts of air and not sending the excess anywhere when shutting the throttle puts HUGE loads on the turbos, pipework and throttle butterfly. If the only gripe with them is noise then personally I'd put up with that (and did) and revel in the knowledege that I'm doing my bit for longevity. Quote Link to comment Share on other sites More sharing options...
Steve Cargill Posted June 20, 2003 Share Posted June 20, 2003 Originally posted by Chris Wilson Sometimes they will hit surge, depends on a huge array of variables, but BOV's were really "!invented" for noise issues when turbos were fitted to passenger cars, I can think of no serious race engine apps where a BOV is used unless it was "there" in the road car application it may have been based on. F1 turbos, Indy cars, blah blah never used a BOV, and they were pretty interested in reliability and rapid spool up. Chris, I thought the Indy cars had a BOV. About 1 foot behind the roll bar sticking out of the top. Don't they call it a pop-off valve, or is that something different? Quote Link to comment Share on other sites More sharing options...
Adam W Posted June 20, 2003 Share Posted June 20, 2003 A pop off valve is a mechanical weak link in the inlet tract that gets blown open if you get a big boost spike and stops the engine self destructing. Not sure if these are "reusable" or not though, ie once they open is that race over or do they close themsleves again and you keep going. They use them on Top Fuellers and those ones just bust open and have to be replaced afterwards, I would imagine racing car ones are spring loaded or something? Quote Link to comment Share on other sites More sharing options...
JohnK Posted June 20, 2003 Share Posted June 20, 2003 I think in INDY cars the pop off valves are supplied, set and sealed by their eqivilent of the FIA to make sure the boost level stays within the rules. the do reseal themselves but the car will lose time every time it happens. Quote Link to comment Share on other sites More sharing options...
Guest Terry S Posted June 20, 2003 Share Posted June 20, 2003 Nathan this is no wind-up. Kinda wish it was:( Quote Link to comment Share on other sites More sharing options...
Nathan Posted June 20, 2003 Share Posted June 20, 2003 Oh dear. Again, in the interests of trade relations I would normally back out of threads like this now but I think that many people here would be interested to know who these fools are. Having the odd tiff with a customer is one thing but this is clearly something a bit scarier. I'm in no way advocating name and shame here (and thats even assuming you know who it is Terry) but all I will say is that you need to be 101% on the facts if you do. Regards, Nathan TDI PLC Quote Link to comment Share on other sites More sharing options...
Guest Terry S Posted June 20, 2003 Share Posted June 20, 2003 Nathan, I understand what you are saying & I am sure you understand my reluctance to tell people who the tuner is. The statement about the BOV came from the owner quoting the tuner. The fact that there is not one on the car came from another tuner who is in the process of rectifying all the faults with the car. Quote Link to comment Share on other sites More sharing options...
Need4Speed Posted June 20, 2003 Share Posted June 20, 2003 Indy Car (or to use the correct term now Champ Car) pop-off valves are supplied by CART to limit the level of boost. They are returned after each session. Quote Link to comment Share on other sites More sharing options...
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