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Sept 10, 2017 21:23:14 GMT
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What the best make of BOV for ditching the boost when the throttle is closed. The engine is a 4ltr V8 with waste gate set at 2 bar of boost. Power wise not sure as it yet to go on a dyno but min of 300 to max 800 bhp.
At the moment I'm not get much boost in fact it not even registering on the gauge still so it must be below 1 bar absolute. Soon as the trottle is closed the dump valve opens. The other day while testing in second gears we held on to the revs a bit higher and as the throttle closed the dump valve open but i don't think it opened enough or could ditch the volume of boosted air as one of the pipes off of the inter cooler blew off .
Is there a good reasonable priced dump valve that opens quick and can ditch a lot of air but still capable of holding the boost when needed.
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“It Doesn’t Feel Pity, Or Remorse, Or Fear, And It Absolutely Will Not Stop, Ever, Until You Are Dead!”
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ChasR
RR Helper
motivation
Posts: 10,194
Club RR Member Number: 170
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Sept 11, 2017 0:30:37 GMT
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If it is blowing pipes off even at 2 bar I'd be looking at the pipework? Is it all beaded? Straight unbeaded pipes will having them blowing off in no time.
I was going to say go to Tial for the wastegates but the exchange rates have not helped their prices.
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fad
Posted a lot
Posts: 1,781
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Sept 11, 2017 5:48:22 GMT
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On confused. Your WG is set to 2 bar but you are seeing no boost on your gauge? Is your gauge busted?
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Sept 11, 2017 7:00:07 GMT
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All the pipes are swaged and all have the proper clamps. I should have mentioned that the Turbo is a big one, at the moment on the gauge its still below 1bar absolute, depression. But the turbo is spinning but as the fueling and car isnt set up correctly i only have a small test area, so 2 gear is all i can get up to.
If i could hold the throttle open for longer the boost would (hopefully) build up. I think the problem is that is going from depression then the instant the throttle is shut, with the large amount of air the turbos shifting, to large boost (between the turbo and throttle body) and present BOV cant either open quick enough or can't get rid of that volume of air.
I think the hose blew not as a result of the boost but the speed it happened. Depression to over boost instantly.
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“It Doesn’t Feel Pity, Or Remorse, Or Fear, And It Absolutely Will Not Stop, Ever, Until You Are Dead!”
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fad
Posted a lot
Posts: 1,781
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Sept 11, 2017 7:35:30 GMT
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Ah I see. Hmm. You aren't going to know until you can stretch her legs. Rolling road? Bigger test area?
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Sept 11, 2017 11:34:03 GMT
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Yes either of those would be good but before it can there's a couple of things to sort.
Mainly I would like to know what Blow off valves anyone can recommend for the car to eliminate this ever happening again due to a sudden spike in boost.
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“It Doesn’t Feel Pity, Or Remorse, Or Fear, And It Absolutely Will Not Stop, Ever, Until You Are Dead!”
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fad
Posted a lot
Posts: 1,781
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Sept 11, 2017 15:39:47 GMT
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Yes either of those would be good but before it can there's a couple of things to sort.
Mainly I would like to know what Blow off valves anyone can recommend for the car to eliminate this ever happening again due to a sudden spike in boost. Pass. You need to know what cfm of air you are pushing and spec accordingly I guess? |
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Badger
Part of things
Posts: 250
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Sept 11, 2017 16:17:23 GMT
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I can't help with the actual question, but it looks like the best place for this:
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Last Edit: Sept 11, 2017 16:18:20 GMT by Badger
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froggy
Posted a lot
Posts: 1,099
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Sept 11, 2017 19:45:02 GMT
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Is the bov open at idle and in vac ? . I don't think your making any serious boost as you'd be hearing surge or chatter as you lift if the bov isn't opening.
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froggy
Posted a lot
Posts: 1,099
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Sept 11, 2017 19:50:15 GMT
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If I'm reading correctly and you have a 30pdi spring in the wastegate I'd get it out before any driving in boost . A 12lb spring will give you far more control up to 1.8-2,0 bar boost
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Sept 11, 2017 20:00:05 GMT
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The BOV works and dumps the boost ( quite loud) when off throttle but the i don't think it can dump it quick enough. The two ports don't seem big enough, is was the first time i had pushed that far (rpm & throttle) in 2nd As soon as i let off the dump valve sounded then there was a pop as the pipe blew off of the turbo.
The valve does open on vac (depression) but the turbo can move a fare bit of air as its from an 8lt Scania truck.
The waste gate opened for the fist time when just before the pipe let go, one of lads said there was a blast of black out of the exhaust ( very technical), so as the throttle shut it went from slight depression to over 2 bar in an instant. However, the inlet manifold has yet to see any boost as the engine spins up so quick, i run out of road first.
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Last Edit: Sept 11, 2017 20:22:29 GMT by Bullstarz
“It Doesn’t Feel Pity, Or Remorse, Or Fear, And It Absolutely Will Not Stop, Ever, Until You Are Dead!”
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froggy
Posted a lot
Posts: 1,099
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Sept 11, 2017 20:42:16 GMT
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Sounds more like a backfire that blew the hose off .I'm guessing some sort of Holset hx40
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Sept 11, 2017 22:54:40 GMT
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No backfire, i would have heard that as it's a straight through exhaust system and the injectors would be close soon as the throttle closed. I believe the black from the exhaust was because its the first time the waste gate part of the turbo had opened since I'd had it. It been subject to all sorts rich mixtures while sorting out the injector timing/fueling.
The Turbo a Garrett GT40.
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“It Doesn’t Feel Pity, Or Remorse, Or Fear, And It Absolutely Will Not Stop, Ever, Until You Are Dead!”
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froggy
Posted a lot
Posts: 1,099
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Sept 12, 2017 9:02:14 GMT
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I run two 25mm atmospheric on mine and 50mm is more than enough surface area to vent any pressure . There isn't any restriction anyway as pressure will go backwards through the compressor if there were no blow off valve .
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fad
Posted a lot
Posts: 1,781
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Sept 12, 2017 10:01:15 GMT
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I run two 25mm atmospheric on mine and 50mm is more than enough surface area to vent any pressure . There isn't any restriction anyway as pressure will go backwards through the compressor if there were no blow off valve . And get that chopped WRC noise everyone thinks is wastegate chatter. |
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Sept 12, 2017 18:17:46 GMT
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I run two 25mm atmospheric on mine and 50mm is more than enough surface area to vent any pressure . There isn't any restriction anyway as pressure will go backwards through the compressor if there were no blow off valve . Thanks, that the advise i was looking for, i know that the pulse of air went backwards and hit the air going forwards from the turbo with enough force to operate the waste gate and blow the pipe off. The pipe going to the BOV is 25mm but ports are alot smaller. A few companies have got back to me one has recommended their 50mm, which is a 50mm boss and 50mm piston. That will work just need to get a decent price. The HKS seem decent but unless you get it from a main dealer, and pay full price, you can't be certain is a genuine one. I emailed a few sellers who had them on the eBay (from £20 to £179.00) and they answered, "assumed they were", "Think they must be", "As far as I'm aware it's a genuine item" and "i didn't know they were any copies around". Didn't fill me with confidence. Hope to get a quote from forge tomorrow. |
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“It Doesn’t Feel Pity, Or Remorse, Or Fear, And It Absolutely Will Not Stop, Ever, Until You Are Dead!”
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froggy
Posted a lot
Posts: 1,099
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Sept 12, 2017 20:15:45 GMT
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Mine are both cheap knock offs , took them apart cleaned and polished the Pistons and never had an issue in two years . Have you got a 1 bar spring to put in the wastegate ?
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Sept 12, 2017 22:40:38 GMT
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 I did think a bout getting two of the cheap HKS rip offs, but if they failed and the turbine decided to make it way in to the engine, it would be expensive, compared to the cost of a genuine BOV. Throughout this build i have have to replace cheap parts that have failed or didn't even work. I normally end buying the genuine part after all. So getting some of the cheap parts have ended up costing more. The waste gate is a sealed unit, from the specs it cracks at 1.8 bar (over atm) and will be open at 2 bar. If the exhaust manifolds can flow enough to the turbo the engine will take it. |
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Last Edit: Sept 12, 2017 22:44:20 GMT by Bullstarz
“It Doesn’t Feel Pity, Or Remorse, Or Fear, And It Absolutely Will Not Stop, Ever, Until You Are Dead!”
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froggy
Posted a lot
Posts: 1,099
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Sept 12, 2017 23:38:25 GMT
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You haven't left yourself any control over the boost curve with a spring that stiff . I can just about put 400whp down in third and 4th on warm track tyres .
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Sept 13, 2017 2:45:04 GMT
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