big-phil Posted December 8, 2005 Share Posted December 8, 2005 I do not have an intercooler, and 7psi felt really good for a week or so, but now I want more. But I'm worried. Should I have a blow off valve before going higher than stock psi? Quote Link to comment Share on other sites More sharing options...
oinojo Posted December 8, 2005 Share Posted December 8, 2005 turbo apps should always have a BOV no matter how much boost it regulates. Unless you have enough bank to buy new turbos Quote Link to comment Share on other sites More sharing options...
Sparks280zt Posted December 8, 2005 Share Posted December 8, 2005 turbo apps should always have a BOV no matter how much boost it regulates. Unless you have enough bank to buy new turbos Thats why the l28et came with one from the factory? I also feel Clifton gettin ready to chime in with his 20+ psi beast that has no BOV Quote Link to comment Share on other sites More sharing options...
stagefumer11 Posted December 8, 2005 Share Posted December 8, 2005 Isnt it the fact that from factory they are running low amounts of boost which isnt enough to cause backspool?. My l20et came with a system that worked like a bov. I say if you going to be winding the boost up in anyway, get a BOV. Plumb the retun back into the intake. And woolaaaa. Quote Link to comment Share on other sites More sharing options...
Sparks280zt Posted December 8, 2005 Share Posted December 8, 2005 Isnt it the fact that from factory they are running low amounts of boost which isnt enough to cause backspool?. My l20et came with a system that worked like a bov. I say if you going to be winding the boost up in anyway' date=' get a BOV. Plumb the retun back into the intake. And woolaaaa.[/quote'] Oinojo said "turbo apps always have a BOV no matter how much boost it regulates" which is not the case Quote Link to comment Share on other sites More sharing options...
24OZ Posted December 8, 2005 Share Posted December 8, 2005 I have one and I'm running 7psi so i cant really talk but... as someone else said, if you are using the turbo manifold their is a BOV between the 3rd and 4th runner. Also some say that adding an aftermarket BOV that vents to atmosphere is not technically a good thing to do if you are running the L Jetronic EFI since the very nature of the EFI system uses an air flow meter to measure the exact amount of air entering the engine and a BOV would release that air that was already metered. The result would make the engine run rich which isnt necessarily a bad thing for a turbo engine but isnt efficient either. Quote Link to comment Share on other sites More sharing options...
J Taylor Posted December 8, 2005 Share Posted December 8, 2005 Jack up the boost and don't worry about it for the time being. Although I do have a bov, I personally think they are overrated. I ran my 84 300zx turbo at 10+ psi for a few years and never had a bov on it. JT Quote Link to comment Share on other sites More sharing options...
slownrusty Posted December 8, 2005 Share Posted December 8, 2005 Its cheap insurance and fairly to easy to install, so I recommend it. Yasin Quote Link to comment Share on other sites More sharing options...
thehelix112 Posted December 8, 2005 Share Posted December 8, 2005 Unless someone has evidence to support their claim that it makes no difference, ie, lag between gear changes with and without, or even better, a turbo tacho log during gear change with and without, then I'd be doing it. As slownrusty says, cheap insurance. Dave Quote Link to comment Share on other sites More sharing options...
Pyro Posted December 8, 2005 Share Posted December 8, 2005 I ran 14 psi of boost without a BOV of any kind for a few years without any problems. I recently installed a Turbo XS BOV (bosch style) and recirculated it. I think it does helps keep the boost up between shifts. Not a major difference but noticable. Plus I feel better about not beating up my turbo anymore. Quote Link to comment Share on other sites More sharing options...
big-phil Posted December 8, 2005 Author Share Posted December 8, 2005 hey thanks guys. I guess i'll go ahead and turn it up to 10, and still sleep at night. Quote Link to comment Share on other sites More sharing options...
myplasticegg Posted December 8, 2005 Share Posted December 8, 2005 Most factory turbo cars didn't come with BOVs for the fact that the drivers would have been worried about "that sound." If you're putting any money in your car, buy a BOV. It dosen't have to be anything fancy... just a Bosch plastic POS (aslong as you're keeping the boost below 15psi) or a 1G DSM BOV for high boost apps. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted December 8, 2005 Share Posted December 8, 2005 I think the stock 280ZX Turbo Motor does have a small recirc-valve AND a large pop-off valve. Both are threaded into the intake manifold. The "blow-off" valve is at the end of that little 1/2" hose that comes off the j-pipe and feeds into the intake manifold through that check valve. When I went with an I/C, 14psi, and large TurboXS recirc valve, I glued a dime on top of the stock recirc-valve so that idle would drop faster in between shifts. The stock recir-valve should work for 10psi with the stock turbo. Your safest bet is never to let off the gas pedal! Quote Link to comment Share on other sites More sharing options...
Tony D Posted December 8, 2005 Share Posted December 8, 2005 "Most factory turbo cars didn't come with BOVs for the fact that the drivers would have been worried about "that sound."" Oh gawd! Where do I start? In the DARK AGES things dien't have a BOV, then again they were draw-through carburettors and had no wastegates, either... Porsche Turbos have had a BOV almost from DAY ONE on production vehicles. There is the right way, and then the other way. You really didn't hear Porsche Turbos making "Ricer Flushes" back in 1979 did you? NO, because they properly plumbed the thing and engineered it for proper street manners befitting a car that costs more than a house. Check out the Bentley Turbo R.... And to top it all off regarding "that sound": You don't hear it on the STOCK ZXT, with it's STOCK BOV, so what is the deal! Not installing a BOV in an OEM application was simply a function of the level of the vehicles market demographic, and the stage of engineering development of the system design. Today, with proper engineering, you find MOST are made WITH a BOV of some sort, and from the 80's on, most not catering to low-cost markets had them. Low Boost, low cost vehicles are an exception, not the rule...no matter how many are produced. Quote Link to comment Share on other sites More sharing options...
Sparks280zt Posted December 8, 2005 Share Posted December 8, 2005 Clifton where are you........ Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted December 8, 2005 Share Posted December 8, 2005 Simple answer. Leave everything on a 280ZX motor stock and turn the boost to 10psi. You will be OK but you will reduce the life of the turbo a little. Later, add NOT a blow-off valve BUT a recirculating-valve so that you pose less stress on the turbo and you maintain proper fuel mixtures under all conditions. (with stock EFI and AFM) A blow-off valve will throw air away tha has already been acounted for by the AFM. Not good. A recirc-valve is the same as a blow-off valve EXCEPT it dumps excess air back into the compressor intake to be used again. NOTE: The stock turbo motor uses a spring check valve on the intake manifold to "simulate" a recirc-valve. Quote Link to comment Share on other sites More sharing options...
Cody 82 ZXT Posted December 8, 2005 Share Posted December 8, 2005 turbo apps should always have a BOV no matter how much boost it regulates. Unless you have enough bank to buy new turbos Don't believe the hype!! Quote Link to comment Share on other sites More sharing options...
oinojo Posted December 8, 2005 Share Posted December 8, 2005 Don't believe the hype!! i wont go either way on it since its a very debatable subject. Logically i think its best to go with a BOV even though many do not. If a turbo slowed down dramatically i would think it would hurt the internals of the turbo and cause some kind of reversion on the compressor side. Quote Link to comment Share on other sites More sharing options...
Tony D Posted December 8, 2005 Share Posted December 8, 2005 NOTE: The stock turbo motor uses a spring check valve on the intake manifold to "simulate" a recirc-valve. I would not say it "simulates" a recirc valve---it's function does NOT return the air to prespin the turbine as a "recirc" valve would. Compressor Bypass Valve is actually the proper item to install, one that lifts and bypasses intake air around the turbine during vacuum events and lets the turbo spool while being bypassed. But I digress. The "Stock" valve IS a blowoff valve. It's design is such that at a given pressure differential the valve OPENS venting pressurized air to vent to a low pressure area, keeping high pressure air from slowing the turbo on lift-throttle. At the SAME time it also does some things with preventing a vacuum spike in the intak manifold, decreasing oil consumption during spirited driving. BECAUSE it vents to the manifold, the valve can be FAR smaller than the conventional atmospheric blowoff as the extremely high vacuum really helps that valve relieve pressure on initial drop throttle. The pressure differential at stock boost levels is over 14psi! Quote Link to comment Share on other sites More sharing options...
24OZ Posted December 8, 2005 Share Posted December 8, 2005 Since we are talking about the stock BOV. Would you have to remove it and cap it off if you were going to run more then 10psi of boost? Quote Link to comment Share on other sites More sharing options...
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