98.5POS

I'm going to put twins on my truck soon, but I'm a little concerned about the amount of boost it'll make. I don't want to be over 50-55 psi. My engine is studded but not o-ringed and I don't want to blow the head gasket.

To my question ---- I've seen blow off valves on setups before but I cannot find where to buy them. Does anyone know off where I can get one that is adjustible? Thanks.

D

bnold

I am using two blow-off valves from Rip at sourceautomotive.biz that are adjustable from 45-120psi

98.5POS

What brand is your blow off valve? I looked on their sight but coudn't find them. It looked like they had two in their twin setup, are those the kind you have? Thanks.

D

bnold

No idea on the brand, but yes they are the ones shown on the twins setup

98.5POS

Just a few more questions. What pressure do you have yours set at? Are they effective? Are they loud when they blow off? I was told that you can take that style and plumb them into your exhaust to get rid of the noise, do you have yours that way? Thanks.

D

bnold

Between the stacks and engine noise I can't hear mine... I've had them set at 50psi for a few months and just raised them to 60psi... Extremely effective, work great... Mine are not venting to anything just the engine bay...

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TxDiesel007

I have the same setup

I have mine go off currently at 60 psi max, but i have turned them down to 50 PSI before, they are not too loud when they go off, u kinda have to be listening for it and watchin the boost gauge at the same time to see the pressure release. I have mine directly on the pipe that goes to the intercooler. They are effective for the setup, but im thinkin an external wastegate might be a better option...

Rick

98.5POS

Aren't blow off valves and waste gates the same thing?

gman07

Nope.

Blow-off valves dump air out of the intake (compressed) side when you rapidly drop the throttle to prevent barking the turbo. In this case, they're being used to limit boost.

Wastegates bypass exhaust gases around the turbine wheel after a certain boost is reached to control turbine speed.

600 Megawatts

Blow off valves serve no effective purpose on an engine without a throttle (our diesels). The purpose of blow off valves on gassers is so when you let off the go pedal quickly and the throttle butterfly slams shut, the rapid increase in compressor discharge pressure is relieved. On a diesel, you dont have a throttle and thus you dont have this problem.
And to use a blow off valve to control boost, is a tremendous waste of power. When you do this instead of using a wastegate you are forcing all of the exhaust gas to pass through the turbine where it recovers the heat and pressure energy from the engine exhaust to drive a compressor at a speed higher than you want, and thus deliver a boost pressure higher than you want, only to vent the excess boost out a blow off valve. Use a wastegate instead, and then bypass your exhaust around the turbine to control the amount of power the turbine delievers thus controlling the compressor boost in that manner. You'll have lower engine exhaust back pressure and lower EGTs not to mention more power.

Remember, that boost does not come free. It robbed some engine power to make it. Use all the boost you make, or if you've got more boost than you want, wastegate the engine exhaust around the turbo before you make it, thus freeing up engine power.

If you ever find a compressor that compresses air without using any power.... let me know, we'll make alot of money together.....

Kp

98.5POS

Which would work better as far as EGT's go? I'm planning on building my own twin setup so I can build how I want. The blow off valves look extremely easy, whereas wastegate on the exhaust side doesn't seem to be as easy. But if the wastegate works better then so be it. What do you guys think?

D

gman07

If I was building a set of twins, I wouldn't even have to think about it. Wastegates.
I'd probably also use external wastegates unless I planned on using a wastegated turbo I already had.

98.5POS

I'm using my HTB2 (wastegated) and a HT3B (non-wastegated). So a external wastegate would mount where on a twin set-up? On the hot pipe between the two, and exciting in the exhaust down tube?

98.5POS

Turbonetics makes an external waste gate, where do you mount it?

bnold

I imagine if you went the external wasteagte route you would gate the primary by placing the wastegate into the hotpipe