csa Posted July 9, 2008 Share Posted July 9, 2008 put small welding "knobs" around the end of your IC pipes, use top quality mikalor style clamps and 4PLY silicone. should hold it togheter then Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted July 9, 2008 Share Posted July 9, 2008 Holy Giant Photo Batman! That looks very cool though, did you get a drive? Sadly no I did did sit in it and hold the brakes on whilst the wheel nuts were torqued though. With a value of over 400,000 UK pounds I don't think I'd like to put it into the barriers or pop an engine! Quote Link to comment Share on other sites More sharing options...
Wez Posted July 9, 2008 Share Posted July 9, 2008 I was helping a friend work on something VERY exotic at Donington today. A Nissan R90 CK Group C car, probably the most complex and fastest Group C car of the early nineties, if not all time excluding the V6 cars (these were twin turbo V8's) The electronics and pneumatics were simply awesome, as was the build quality and on track, its speed. Did it have a BOV? No. It did have ecu controlled twin IC bypass valves, WI, cockpit adjustable boost, mixture and timing, individual cylinder knock sensors, and EGT prbes that also were read and acted on by the ECU. Complex is actually an understatement. The engine ECU had 4 MIL connectors with about 300 pins in total. I am sure if a BOV was a performance aid, or, as this was a winning 24 hour car, an aid to longevity, it would have had one or more. They are noise reducing devices, for production cars, and noise creating devices, for the aftermarket. It's one of my favourite race cars of all time, chancing on it in the pit garages on a (albeit upmarket) track day was good enough, to find it being run by a pal of mine and given free access to it, inside and out was a dream. I am still on a high, a simply stunning machine. I met a guy from a company called Link-Up, or something like that. They build and maintain race cars, he looks after some group C cars and mentioned the Nissan and Jags, apparently at Le-Man the older group C cars were doing 258mph where as the current models only do 230mph. It might be to do with the 4bar boost 1500hp they are running. Apparently someone he knows tried strapping one to a dyno for a power run and it tore the straps and jumped out the dyno, they are obviously mapped on engine dynos. Quote Link to comment Share on other sites More sharing options...
Lee P Posted July 9, 2008 Share Posted July 9, 2008 I would use a dump valve, Chingy's Do luck supra wasnt running one and it now has a large split in the intercooler. Its now getting a dump valve. Quote Link to comment Share on other sites More sharing options...
mikeyb10supra Posted July 9, 2008 Share Posted July 9, 2008 (edited) I would use a dump valve, Chingy's Do luck supra wasnt running one and it now has a large split in the intercooler. Its now getting a dump valve. what sort of boost levels was he running though?? in theory pressure is relieved as soon as your off the throttle, not increased so the damage is going to be done when your pinning it and hitting maximum pressure and the pipes/core are having to hold it. I would have thought a BOV would have no bearing on the IC pipe/core splitting, the pipe rubbing on something and becoming weak or being below strength tolorences would have more of an effect imo Edited July 9, 2008 by mikeyb10supra (see edit history) Quote Link to comment Share on other sites More sharing options...
bolarbag Posted July 9, 2008 Share Posted July 9, 2008 what sort of boost levels was he running though?? in theory pressure is relieved as soon as your off the throttle, not increased so the damage is going to be done when your pinning it and hitting maximum pressure and the pipes are having to hold it. I would have thought a BOV would have no bearing on the IC pipe splitting, the pipe rubbing on something and becoming weak or being below strength tolorences would have more of an effect imo Blow Off Valve A valve that is triggered by the pressure difference in the manifold and gets rid of this excess air. No it doesnt pre throttle, you still have the time it takes the compressor to slow down building positive pressure while doing so(unless you have a bov) pressure is only relieved within the plenum, as soon as the throttle is closed I do agree that for the IC to split it would more than likely have been inadequate build tollerances than full on high pressure within the compressor to IC area, the car would have been under serious compressor stall and you would think the pipes would have blown off first Quote Link to comment Share on other sites More sharing options...
mikeyb10supra Posted July 9, 2008 Share Posted July 9, 2008 (edited) No it doesnt pre throttle, you still have the time it takes the compressor to slow down building positive pressure while doing so(unless you have a bov) pressure is only relieved within the plenum, as soon as the throttle is closed I do agree that for the IC to split it would more than likely have been inadequate build tollerances than full on high pressure within the compressor to IC area, the car would have been under serious compressor stall and you would think the pipes would have blown off first Sorry I dont follow? So what im reading into it im thinking when you back off the throttle your saying the compressor still spinning generates boost with no bov...it wont generate any more though will it and that was the reasoning behind not having a BOV no??, surely it will drop off rather than increase?? After close inspection of the boost gauge in my car with the BOV capped off it instantly drops when im off the throttle Edited July 9, 2008 by mikeyb10supra (see edit history) Quote Link to comment Share on other sites More sharing options...
bolarbag Posted July 9, 2008 Share Posted July 9, 2008 (edited) Sorry I dont follow? So when you back off the throttle your saying the compressor still spinning generates boost with no bov?? After close inspection of the boost gauge in my car with the BOV capped off it instantly drops when im off the throttle Lol - I gather you have a j-spec, thats because your Map sensor reads from the plenum!! edit - it read differently twice there...your BG will be tapped into the plenum which is under vacuum until positive boost the compressor still spinning generates boost with no bov?? Yes - at around 150K rpm not even high pressure will stop a compressor instantly, Edited July 9, 2008 by bolarbag (see edit history) Quote Link to comment Share on other sites More sharing options...
mikeyb10supra Posted July 9, 2008 Share Posted July 9, 2008 Lol - I gather you have a j-spec, thats because your Map sensor reads from the plenum!! yep, and the gauge is tapped into the TPS Yes - at around 150K rpm not even high pressure will stop a compressor instantly but thats the point im trying to make, I totally agree with you but I fail to see how this has any bearing on pipes splitting. Yes it generates more boost but as soon as your off the throttle although it generates boost while its still spinning its always reducing Quote Link to comment Share on other sites More sharing options...
jevansio Posted July 9, 2008 Author Share Posted July 9, 2008 I would use a dump valve, Chingy's Do luck supra wasnt running one and it now has a large split in the intercooler. Its now getting a dump valve. This is the sort of thing putting me off, with no bov, popping hoses & splitting intercoolers isn't something I want to contend with Quote Link to comment Share on other sites More sharing options...
tDR Posted July 9, 2008 Share Posted July 9, 2008 When you back off the throttle, the throttle butterfly closes and is effectively a 'wall' in the intake tract. At that exact moment there is still boost pressure exiting the compressor which will effectively hit said wall. This is where no BOV is risky - the pressure build at this exact moment is higher than just being on boost when the throttle plate is open and the engine is consuming the output of the compressor. A BOV, at that exact moment, would open to relieve this excess pressure... I think for this reason I would tend to run one rather than testing the pipes, clamps, IC welds etc. at that moment with an unknown pressure build up higher than when on full throttle / full boost conditions. It's all very well commenting on race cars not running BOV's etc. but ultimately all the pipework, clamps, welds etc. etc. will be of a much higher quality than we run on our modified road cars and so more likely to get away with it. Cheers, Brian. Quote Link to comment Share on other sites More sharing options...
bolarbag Posted July 9, 2008 Share Posted July 9, 2008 but thats the point im trying to make, I totally agree with you but I fail to see how this has any bearing on pipes splitting. Yes it generates more boost but as soon as your off the throttle although it generates boost while its still spinning its always reducing Lets just say you have 1bar of boost within the pipes coming from the compressor and then all of a sudden the compressor begins to push against nothing(throttle closed), the pressure within the pipes will be immence, it wont just be 1 bar it could be 3 for the split second that it takes to fill the route with air and needs to escape back through the compressor - meaning the compressor still spinning is pushing against an opposite force until the compressor slows down - this all happens very quickly even if the compressor is spinning at 150k rpm but it doesnt happen instantly which is the time for something to blow off/get damaged e.t.c Why risk the back pressure on the compressor when you can install a bov that rids the route of built up air This situation is even worse track driving, where these open/close throttle conditions happen continuously, and the compressor doesnt have time to slow down I'm pretty surprised that CW's mate didnt have one but if you never cared for longetivity then not having a bov would increase response I would imagine, as in open/close throttles there would be a continuous supply off positive boost albeit at a varied level Quote Link to comment Share on other sites More sharing options...
mikeyb10supra Posted July 9, 2008 Share Posted July 9, 2008 Lets just say you have 1bar of boost within the pipes coming from the compressor and then all of a sudden the compressor begins to push against nothing(throttle closed), the pressure within the pipes will be immence, it wont just be 1 bar it could be 3 for the split second that it takes to fill the route with air and needs to escape back through the compressor - meaning the compressor still spinning is pushing against an opposite force until the compressor slows down - this all happens very quickly even if the compressor is spinning at 150k rpm but it doesnt happen instantly which is the time for something to blow off/get damaged e.t.c Why risk the back pressure on the compressor when you can install a bov that rids the route of built up air This situation is even worse track driving, where these open/close throttle conditions happen continuously, and the compressor doesnt have time to slow down I'm pretty surprised that CW's mate didnt have one but if you never cared for longetivity then not having a bov would increase response I would imagine, as in open/close throttles there would be a continuous supply off positive boost albeit at a varied level Ahh thats much clearer I see where your coming from now and its a good point Quote Link to comment Share on other sites More sharing options...
tDR Posted July 9, 2008 Share Posted July 9, 2008 Fine then, ignore me I'm jumping all over your next 'buy hybrids' post Quote Link to comment Share on other sites More sharing options...
jevansio Posted July 9, 2008 Author Share Posted July 9, 2008 I think my mind is made up in this matter, it's a BOV for me, thanks for the input everyone Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted July 9, 2008 Share Posted July 9, 2008 When you back off the throttle, the throttle butterfly closes and is effectively a 'wall' in the intake tract. At that exact moment there is still boost pressure exiting the compressor which will effectively hit said wall. This is where no BOV is risky - the pressure build at this exact moment is higher than just being on boost when the throttle plate is open and the engine is consuming the output of the compressor. A BOV, at that exact moment, would open to relieve this excess pressure... I think for this reason I would tend to run one rather than testing the pipes, clamps, IC welds etc. at that moment with an unknown pressure build up higher than when on full throttle / full boost conditions. It's all very well commenting on race cars not running BOV's etc. but ultimately all the pipework, clamps, welds etc. etc. will be of a much higher quality than we run on our modified road cars and so more likely to get away with it. Cheers, Brian. This has moved on a bit, anyway i agree, and the bigger the turbo the more you need a BOV as the inertia involved makes a big difference, you can get away with it running small turbos as the inertia is quite easily overcome, bit it wont do big ones any favours, same goes for weak pipework/joins, The one thing to remember when mentioning the race car scenario is that they will probably chuck or rebuild a turbo after a race;) Quote Link to comment Share on other sites More sharing options...
mikeyb10supra Posted July 9, 2008 Share Posted July 9, 2008 Fine then, ignore me I'm jumping all over your next 'buy hybrids' post Quote Link to comment Share on other sites More sharing options...
Thorin Posted July 9, 2008 Share Posted July 9, 2008 Sadly no I did did sit in it and hold the brakes on whilst the wheel nuts were torqued though. With a value of over 400,000 UK pounds I don't think I'd like to put it into the barriers or pop an engine! Did you make engine noises and pretend you were driving though? Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted July 9, 2008 Share Posted July 9, 2008 (edited) Did you make engine noises and pretend you were driving though? Actually..... yes http://www.calumlockie.com/news/report49.html Jammy *astard, came home third in Spa in the last round. Edited July 9, 2008 by Chris Wilson (see edit history) Quote Link to comment Share on other sites More sharing options...
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