Project 350HP update

[SmithvilleD]

I think the turbo will be a big factor in our goal. Question for you, I PMd TD about this earlier and wanted to get your thoughts. With this non-wastegated turbo and the fact that we are adding nitrous, propane, and water/meth, do you think we should put a blow-off valve on the intake to help from over boosting? I was able to reach over 20 psi with a GM-4 on my truck and didn't want to be putting 25+ psi on this heads. This truck does have 20:1 comp and ARP head studs.

Most blow-off valves aren't designed to vent boost in a way that will allow for a smooth, well controlled boost peak/limit. Better to limit boost/turbo shaft speed with a non-wastegated turbo by controlling/limiting turbine drive energy. In other words, do sequential runs adding a bit more fuel each time, upping drive energy, until you've hit the max boost pressure you dare run.

 

[6.5quest]

Thanks for the info guys, I will let you know what we decide. Here is an update on the trucks progress. I will post pictures later today after my Seahawks play!

Nitrous system install 100% complete (not tested yet)
Snow MPG-Max Water/Meth 100% complete
Heath propane system 100% complete
FS-2500 oil bypass system 0% complete (waiting on parts)
A-Team Turbo 50% complete (waiting on new oil return line)
8 new Danin Optix gauges 0% complete (waiting for parts)
High idle switch 0% complete
Airdog fuel system 0% complete (waiting on parts)
FTB mod 0% complete (waiting for airdog system to start this one at same time)
aFe stage 2 intake 100% complete

Thanks again for all the help.

Ian

 

[Slim Shady]

I think the turbo will be a big factor in our goal. Question for you, I PMd TD about this earlier and wanted to get your thoughts. With this non-wastegated turbo and the fact that we are adding nitrous, propane, and water/meth, do you think we should put a blow-off valve on the intake to help from over boosting? I was able to reach over 20 psi with a GM-4 on my truck and didn't want to be putting 25+ psi on this heads. This truck does have 20:1 comp and ARP head studs.

I would put a blow off valve on it. I am not sure what kind of boost you will get with Nitrous and propane added to the mix.

 

[6.5quest]

That was my thought as well.

 

[SmithvilleD]

Have you used a BOV in this way before?

Not trying to tell you how to do your project. Just don't think you're going to like how most BOV's vent in this type of an application using it as a safety valve.

Most BOV's set/sprung to reliably contain 20 psi boost, aren't going to break open/vent smoothly & vent in a way that just bleeds off excess boost & maintains your intended 20 psi (or whatever the target is).

They're designed to open from a notably sharper, more sudden pressure spike than your ATT application is likely to present. Many of them designed to contain 20+ psi boost in gasser applications will also work best with vacuum from under the carb throttle plate plumbed to one side of the diaphragm, so the throttle plate slams shut during a shift, & both the intake tract pressure spike & some vacuum are working to pop the valve open cleanly/quickly.

As a generality, the higher pressure they're set to contain, the more cantankerous they can get. There's a good bit of variability in how the different brands work also.

Not saying this can't be made to work, but many BOV's will tend to chatter/ocillate when venting from a relatively gradually building boost. Be cautious as the resulting pressure inconsistency can be hard on the turbo.

 

[540s10]

Using a blow off valve to vent to the proper boost level is what Procharger does for their race kits... They market it as a BYPASS VALVE... I used one when my 540 was procharged and it worked fine. The centrifugal supercharger ramps boost just like a turbo.

 

[Matt Bachand]

I think the purpose of the BOV is to prevent damage, not to smoothly regulate boost in this application.

THis way if the BOV blows, he knows not to push the 'drugs' as hard, before head gaskets or worse happens.

I may be wrong.

 

[SmithvilleD]

Using a blow off valve to vent to the proper boost level is what Procharger does for their race kits... They market it as a BYPASS VALVE... I used one when my 540 was procharged and it worked fine. The centrifugal supercharger ramps boost just like a turbo.

Is the primary intent of the bypass valve truly to limit/control peak boost at WOT, or to protect the compressor from surge/flutter when the throttle blades shut at high boost levels?

I'm not trying to be argumentative as you may well have a setup I haven't seen before. The race ProCharger setups I've been around adjusted boost curve by changing pulley diameter/compressor rpm.

Now that you mention it, I have heard of a guy with a ProCharger running some type of controller that could vary the duty cycle of a solenoid in the vacuum line of his bypass valve - essentially trying to control boost venting similar to electronic controller/solenoid/wastegate control stategies. He was in a very tire limited class & wanted more control than he felt he was able to get with his selection of pulley sizes.

Out of curiosity, I may stop by ATI. I live near Kansas City & know a couple guys at ATI. Used to be some local racers would dumpster dive there after hours for discarded mandrel bends/IC tubing.

 

[6.5quest]

My main purpose behind using a blowoff valve was to limit unsafe peak boost pressure spikes. Anything over about 22 psi. I worked with a company to design coupler boots that also specializes in turbos and BOV's so I was planning on calling them tommorrow. Since all the drugs will not be used at the same time except for on the dyno pull I don't think the valve will even be used during everyday driving and towing applications with the way I am going to detune the truck after the dyno pull. Just wanted to see what you all thought and I am glad for your responses.

Thanks again,

Ian

 

[3500GMC]

De-tune? What does THAT mean?

On kill I say.

 

[SmithvilleD]

Yeah, the company techs should know if they've got an offering that will behave as you want it to in your application.

I made my comments because I've used a number of different BOV's on various turbocharged gas engines over the years.

Running WOT at 25 psi, let off the throttle quickly to shift & a good BOV, properly setup will pop open cleanly. The challenge typically comes in getting the BOV (still adjusted to remain sealed against consistent 25 psi) to open cleanly at lower boost pressures (say 5-10 psi) when the throttle closes to shift. Many BOV's will ocillate & allow compressor surge/chatter under the lower boost conditions where the BOV doesn't see as pronounced a boost spike.

Understand your concern with multiple fuels & nitrous complicating controlling turbine drive pressure simply with your foot.

 

[Turbine Doc]

6.5Q

I think I would rig some sort of defuel scheme, that is what GM uses with the original GM turbo if it can't lower boost by opening the WG it defuels ergo lowers the drive gas pressure which IMO would be better way to control boost, set up with a NC relay for your pane/nitrous, then have a pressure switch set for your boost safety limit to open the contacts on the relay so flow of fuel enhancements stops

 

[SmithvilleD]

6.5Q

I think I would rig some sort of defuel scheme, that is what GM uses with the original GM turbo if it can't lower boost by opening the WG it defuels ergo lowers the drive gas pressure which IMO would be better way to control boost, set up with a NC relay for your pane/nitrous, then have a pressure switch set for your boost safety limit to open the contacts on the relay so flow of fuel enhancements stops

I agree with TD. If you can get a pressure switch that acts precisely enough to consistently trip at the boost limit. Defueling is the typical strategy OEM's use on diesels with non-wastegated turbos.

Using vent valves on the compressor/boost side as a method of boost control is dead-n-gone for good reason. The additional work the compressor puts in compressing the vented air is wasted work & additional heat going into the charge air.

 

[Turbine Doc]

Mite have to figure some sort of delay also so that when it defuels/deboosts it takes X seconds to reset so you don't wind up in a on/off back & forth fuel/defuel routine

 

[6.5quest]

Sorry for not getting any new pics up I spent the day installing a new HID headlight system that ended up not working at all so I had to spend the rest of my time putting the factory system back together. As it stands I am going to try and get my fiance to take some pics tomorrow for me of the work that has been done thus far. I am having some trouble with the aFe system fitting to my liking so I am going to have to do some modifications to it.

I was unable to talk to anyone about a BOV but I am hoping to do so tomorrow. I will be sure to let you all know what comes of it.

 

[6.5quest]

So here are some pictures of the new ATT in the truck along with the water/meth injectors and nitrous injector.

 

[6.5quest]

Here are a few more pictures of the water/meth tank, nitrous bottle, and propane tank. I also included the Snow head unit, and nitrous solenoid.

 

[Rodd]

Those look awesome!!!!!!!!! Christmas in October

 

[NVW]

Looks good, would like a ride in that truck

Leo

 

[540s10]

Is the primary intent of the bypass valve truly to limit/control peak boost at WOT, or to protect the compressor from surge/flutter when the throttle blades shut at high boost levels?

I'm not trying to be argumentative as you may well have a setup I haven't seen before. The race ProCharger setups I've been around adjusted boost curve by changing pulley diameter/compressor rpm.

you are correct in the setups you have seen that is the primary purpose, but by varying the spring pressure on the one I had you could bleed off a few psi on the top end to keep things safe. It's not the true intent, but it was effective when I was using it.

another thing you could do is wire up an air solenoid to a pressure switch on the bypass valve that when it hits x amount of psi the solenoid kicks in and cuts off the pressure and shoots the valve open killing boost.