So what exactly is a blow off valve and what is it used for? From my searches it seems that is is some type of automatic valve on or by the turbo that releases excess boost pressure??? I don't know why one needs to do that or if that is correct. Why do people have them and do you, can you put them on a Duramax. It seems from my search that only Jap cars have them. Fill me in please. Why are they important?

This is my new set up I will be offering. The blow offs work very well with the Dmax. It eliminates turbo bark when getting out of the throttle. It will come with a few other components as well.

The production units will be all aluminum color. The way a blow off works is, you have pressure from the turbo side (exhaust) when you are giving it fuel. As soon as you let off, there is no more pressure to keep the exhaust side spining and you have a certain pressure built up in the compressor side (intake), thus it tries to reverse the turbo from 40,000-80,000 rpm in an instant, and WALLA, turbo bark (the famous WHOOS, WHOOS, WHOOS). The blow off releases the pressure in the intake when you let off and the pressure is normalized so no back peddling of the turbo, which most certainly can't be good for the long term.

Stoopid question # 525...................................
How does it know when to blow off the excess pressure?

A special valve that is incorporated with the set up. It will be triggered by the throttle position. It will let the blow off know when it's time to let go.

Super Diesel, is the whole unit minus the blue hose going to be included in your piece? When will they be ready for sale? How much do you guess you will start selling them for? And I imagine that you put these right in front of the turbo, on the exhast (in front of turbo) or tube??? How come I don't/haven't heard much of any of these on our diesel trucks? It seems I only hear of them on the ricers? Is it because not many other companies make them or the fact that not a lot of guys feel that they are necessary?

They include the blue hose as well. They will go in line on the passenger of the engine at the point where the post I/C tube goes in to the intake (same place as the SD manifold). I will have some ready in a few weeks. They are relativly new to the diesel performance world. Only in the last few years have they realy become needed. As pressure rises, so does other means of controlling it properly. They help conserably with the long life of the turbo in a daily driver as well as a competion truck.

Which brings up the next couple questions. Can one put both this and the SD Manifold in place at the same time or will this have a place for the boost sensor built into it like the SD Manifold to get a "two for one" deal? Also, I was looking at your website I had another question about the SD Manifold. I assume that it already comes pre-drilled and tapped for 1 sensor, or does it have 2 places, or neither; it just gives you something aftermarket to drill and tap as many times/places as you like to save from drilling/tapping your OEM equipment. Sorry for all of the questions, I'm new to the diesel game. Thanks for the info and replies.

Blowoffs have been used for a long time in racing gas engines. Due to the throttle plate arrangement in a gasser, it's real easy for turbo outlet pressure to really spike when chopping the throttle (especially in road racers that go up and down throttle fast and often). I remember watching an endurance race (Sebring?) where you could really hear the Porsche racers pop off coming into a hairpin. Turbo outlet pressure spikes are not as critical in the diesel, since the diesel uses fuel injection to control engine speed versus a throttle plate. Diesels do have turbo bark, so SD is right, and it sounds like a solution to the turbo bark issue in diesels - if anybody can work it out, SD can! It looks like there's three plugs for sensor/nozzle installation in the tee below the valve in the picture - more on the other side?

The standard SD manifold comes with 5 ports (3 different sizes). This new one will come with 7 ports (3 different sizes). Thanks for the vote of confidence Tom.

SD, What brand Valve is that? It looks a little like the Blitz one. I had 2 of the HKS ones on my Z and they worked flawlessly.

I have to agree with Tom. Anything that SD makes is top notch. :ro)

SD, could you please keep us posted on the blow off valve, I would love to be a test monkey for your first few. Let me know as soon as you have a set up ready I would love to have one.....:grd: :grd:

It's funny.. I've always been a fan of BOVs and I was debating on whether to post if they were available or not... and then I see this.. Woohoo

Am I right that even with small boost increases, that getting out of the throttle at max boost makes the turbo want to bark, and that we are not even aware of it? If so, then this seems like a must for heavy towing/long turbo life.

I think it's less severe in the diesel than a gasser with a throttle plate that slams shut. Remember that the diesel is an "air pump" and engine speed is regulated by fuel injection. As you "chop throttle", the injectors quit spraying fuel, but the momentum in the engine keeps pumping air through the cylinders and valves. As rpm decreases, there's a "buildup" in the turbo outlet and less heat coming out of the exhaust so you get pressure on the compressor and lose drive on the turbine. The more radical the slowdown and the higher the starting speed will get you a good bark (like coming out of a sled pull) but regular driving or towing should give you less severe transitions.

I want to be in line for one!! I make my truck whoose too many times!!! It would be great for after a burn out, some place i run at done have enough room for me to ease out of back peddle..

How loud will the blow off be? like a little pocket rocket or not loud at all? any news on the availability?

thanks,
Jared

They basically sound like when a semi's air brakes relieve pressure.

Sign me up.
where do I send the money for one.
how loud will the blow off sound be?

SD are they out yet? Price?

if its as loud as a semi's breaks, it would really scare the crap outta the little rice burners):h

After further development, I found them to be very similar to the BD model. I do not want to encroach on there products so I don't think these will see production from me (sorry to say).

Super Diesel,

You're such a tease.

After further development, I found them to be very similar to the BD model. I do not want to encroach on there products so I don't think these will see production from me (sorry to say).
:rippedhan