Who is running a big single charger & is it wastegated?
If not gated why not?
I am kicking around which way to go...Thanks
If not gated why not?
I am kicking around which way to go...Thanks
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Turbo /Wastegate question
- Thread starter TNRGreene
- Start date
S474 and no gate but wish I had one. From some of the maps I have seen these chargers are out of their map around 35-40psi and I am spinning mine 60+psi. I would love to be able to bring it back down.
I really like the looks of RDL's new pedistal:thumb:
I really like the looks of RDL's new pedistal:thumb:
My GT4202R set-up needed a wastegate too.(I thought). I saw 60-62 lb. on the sled track and 58 on the race track. I think it would have been better for me to gate it at 48-50 lb...............but I'm no turbo-oligist.
My thoughts (yeah, I'm currently ungated):
Unlike a gas engine, we don't really care about the boost number itself since we do not detonate from too much boost. We care about drive pressure since it's a parasitic loss and drives up EGT's.
A simple adjustable pop-off valve might be a better fit for diesel applications. Boost goes up, then levels out, then goes down as RPM climbs. A pop off valve will stay open at high RPM's even if the boost falls because we went off the map. A wastegate will close again and try to make more boost.
Unlike a gas engine, we don't really care about the boost number itself since we do not detonate from too much boost. We care about drive pressure since it's a parasitic loss and drives up EGT's.
A simple adjustable pop-off valve might be a better fit for diesel applications. Boost goes up, then levels out, then goes down as RPM climbs. A pop off valve will stay open at high RPM's even if the boost falls because we went off the map. A wastegate will close again and try to make more boost.
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A BOV goes on the compressor side, a pop-off valve goes on turbine side. A pop-off is like a wastegate, but has no diaphram and doesn't use a boost reference. Pressure forces the valve open, like the emergency valve on a water heater, but closes again when the pressure drops. Just a spring and a valve.
That link looks just like the valves I bought (www.mcmaster.com) for my water tank to avoid overpressurization. If so, they won't work at higher temps. They are rated at 250 deg, so might even be marginal for engine bay usage.
That link looks just like the valves I bought (www.mcmaster.com) for my water tank to avoid overpressurization. If so, they won't work at higher temps. They are rated at 250 deg, so might even be marginal for engine bay usage.
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You don't have to. Picture a SBC exhaust valve with the spring on it. Say it's 2 sq in of surface area. And the static seat pressure is 200lb. When the drive pressure gets up to 100psi, it will lift the valve and bleed off. You'd want to isolate the spring from the exhaust gases or it will soften the metal. By using different springs, or shimming, you can adjust the purge point.
As far as twins go, I can't see why it would be different, except on really big ones, where neither gates or a pop-off would even actuate.
Very few diesels use wastegates. Normally they size the turbo specifically for the RPM and displacement with a reasonable target boost in mind. But since many of us make a habit of running far more boost than the compressor was designed to supply, it can certainly improve turbo life, and perhaps piston and valve life.
But here's the catch. Say I run the HTT turbo safely at 34psig and it makes 620hp. I can crank the wastegate shut, build 42psi, and overspeed the turbo to 675hp.
Temptation is a killer.
so when looking at wastegate options, when the spring is rated at, say, 12 lbs, what does that mean? will it start to bleed pressure at 12psi of boost? i thought i read somewhere that a WG operates from a pressure differential, and when there is a difference of pressure on both sides of the piston or valve that = the rated spring pressure, it will open, or close. am i way off? otherwise it would just be a BOV or pop-off valve or whatever you guys call them, venting into the exhaust and not atmospherically or into the intake.
As Pat mentioned, spring pressure is dependent on area of load and of two factors. One: how much exhaust pressure is pushing against a wastegate and two how much, if any, boost is pressing on the wastegate. What I mean is, what kind of wastegate do you have or are you looking into installing? 12psi spring on a closed valve will hold back 12 pounds of load on a 1 square inch surfaced valve. This same 12psi spring will only hold back 6 pounds of load per square inch on a 2 square inch valve.
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well i looked at the engineered diesel's 50mm gate, and the synapse 50mm gate
http://cgi.ebay.com/ebaymotors/SYNAPSE-50MM-V-BAND-TURBO-WASTEGATE-NO-FLANGES-WG002A-1_W0QQcmdZViewItemQQhashZitem5d27f3501bQQitemZ400102215707QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories
the link is for the synapse unit. i am planning for a big twins build, very similar to trent's, utilizing a S475-ish with a 83/87 1.0 turbine and a S595-ish.
http://cgi.ebay.com/ebaymotors/SYNAPSE-50MM-V-BAND-TURBO-WASTEGATE-NO-FLANGES-WG002A-1_W0QQcmdZViewItemQQhashZitem5d27f3501bQQitemZ400102215707QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories
the link is for the synapse unit. i am planning for a big twins build, very similar to trent's, utilizing a S475-ish with a 83/87 1.0 turbine and a S595-ish.