Dr. Performance modules

[Wireman76]

Hey, is anybody out there using these Dr. Performance Modules. They claim to lower to exhaust temps, and put the hp gains at the wheels not the flywheel?

 

[lmills]

Some have used them and like their products. Others have found that they exagerate the HP gains. It all depends on who you ask. Most will tell you to stay clear of them.

 

[yycguy]

Hey, is anybody out there using these Dr. Performance Modules. They claim to lower to exhaust temps, and put the hp gains at the wheels not the flywheel?

Hi, I had the Predator stage 3, it was a awesome simple box for power and the egt's where controllable. I had one huge concern though, and that was HI rail pressure. I have heard others mention this as well, and a friend of mine blew his HPR relief valve 2 times. I chickened out on the box and pulled mine.

Just info you should be aware of before making your decision.

Good luck

 

[TravisG]

I don't know anything about Dr. Performance boxes, but if you increase Hp at the flywheel doesn't that transfer to the wheels?

 

[Wireman76]

I'm not sure but i've heard that the stock torque converters don't handle much over what the Cummins 600 puts out, so that extra hp may or may not make it to the wheels?

 

[TravisG]

I see your point Wireman. I didn't think of it that way.

 

[DocDetonancour]

Hi, I had the Predator stage 3, it was a awesome simple box for power and the egt's where controllable. I had one huge concern though, and that was HI rail pressure. I have heard others mention this as well, and a friend of mine blew his HPR relief valve 2 times. I chickened out on the box and pulled mine.

Just info you should be aware of before making your decision.

Good luck

WTH? The Predator literature "guarantees" unit is undetectable by dealer?

 

[yycguy]

WTH? The Predator literature "guarantees" unit is undetectable by dealer?

Yeah unless they ask why the rail pressure was at 25K+ ! and yes they can see that from what I am told (dealer that is)

 

[DLeno]

The rail pressure acheived by the aggressive pressure boxes probably exceeds 28,000 psi, believed to be the set point of the pressure relief valve. Predator is only one of several aggressive boxes out there, and they don't make any more pressure than the others. any pressure box delivering 90+ horsepower to the rear wheels probably pops the valve.



There are two ways the dealer can tell if you have been running a pressure box. if you have an engine failure and the MIL comes on, the state of the engine is captured, including the rail pressure that the ECM is commanding. turns out that actual rail pressure above 26,000 cannot be measured, but commanded pressures of 28,000 PSI or more are would be possible.



The 2nd way they can tell is if your pressure relief valve is toasted. its set point is believed to be 28,000 but could have some variability from truck to truck. That said, a failed pressure relief valve is compelling evidence to the dealer that the truck has been operating with this valve open. Its true that this evidence is not 100% solid, as I have heard of some stock trucks failing the valve. apparently there have been some bad parts shipped out.

 

[yycguy]

Great info DLeno, I was not trying to single out Dr Performance. But yes it is one of the more aggressive Pressure box's out there. The box worked as advertised for me, but as for my buddy his relief valve blew twice in 2 months. The service manager pulled him aside and stated that they would not fix it again under warranty as they new he must be running a pressure box to get rail pressure that hi!

yycguy

 

[KERMA]

I wonder if there's a way to fit the pressure relief valve with a stronger spring to help with this "pressure box" problem. Maybe there's a possibility for a higher range pressure sensor, also, so it's not limited to 26kpsi.



Anyone have the part number for the relief valve? I think I want to get one and fool with it a little.

 

[JStieger]

Anyone have the part number for the relief valve? I think I want to get one and fool with it a little.

Kerma-



I looked up the following:



pressure relief valve #3947799



pressure sensor #3949988



Couldn't find out the price though - I think Cummins Intermountain is open today in SLC though.

 

[DLeno]

I wonder if there's a way to fit the pressure relief valve with a stronger spring to help with this "pressure box" problem. Maybe there's a possibility for a higher range pressure sensor, also, so it's not limited to 26kpsi.



Anyone have the part number for the relief valve? I think I want to get one and fool with it a little.

I've heard of guys shimming the spring. keep in mind that the pressure relief valve is (believed to be) set at 28,000. the pressure sender that sits just forward of this valve and appears to be limited to pressures under 26,000 PSI or so. more info in TDR #47.



boy if you find a higher range sensor let us know! also it would be great to know if the 600s and 610s use the same part as the 555s. Last I was told these were both STAR approved items only. My dealer is pretty good about getting stuff and he couldn't get me a sensor without a documented failure and STAR involvement. Tommygun maybe you have an inside track here?

 

[KERMA]

Even a take-off failed relief valve would be good- I'm not gonna use it, just reverse engineer it. I know a great place to make springs, it's all they've done for 30 years. Anyone have a take-off to donate to the "cause"?? Or is Bosch really tight with these, I guess I'll try calling around on Monday. Cummins will probably want a CPL, which I don't have handy, but it's somewhere to start.

Happy New Year.

 

[Ron Civita]

Is the rail pressure on a stock engine constant or does it increase/decrease with power? And with a pressure box on, is the rail pressure constant or does it increase/decrease with power? And how does this tie in with the relief valve?



Thanks and Happy New Year.

 

[DLeno]

Bosch tight with these things? is the pope catholic? good luck on that. you can come up with a pressure relief valve retrofit or replacement spring...



Rail pressure on the stock truck is constantly varying. you can visualize the behavior of rail pressure by pretending that it is the only way the ECM can adjust the amount of fuel delivered to the cylinder. it isn't of course (both pressure and duration are dyamically changed).



At idle, the 305 HP engine rail pressure stays at approximately 5,000 PSI. A bit lower, actually, and when cold it idles a bit higher than 5,000. When you rev it up in neutral you can see the rail pressure gauge ramp quickly up to 10,000, like you were watching an RPM gauge.



While driving, rail pressure and injector duration are constantly changing and All I can witness is rail pressure. What I observe is that the stock truck dials up a rail pressure between 5,000 and 23,000 PSI depending on the power output of the engine. WOT runs near 3000 RPM run up just over 23,000 PSI. basically rail pressure and injector duration are like shutter speed and aperature on your camera.



Pressure boxes force rail pressure to ramp up much quicker than stock and to a higher level. This forces more fuel into to the cylinder and causes the ECM to back off of duration to maintain the same power level. just like a wider aperature forces a faster shutter speed to maintain the same light level.



When rail pressure peaks up above a certain point, the stresses on the rail increase, and to relieve this, Bosch installed a mechanical pop-off valve, just like the one on a hot water heater. if rail pressure exceeds a certain value (the set point of the pressure relief valve) the valve will open, drain fuel from the rail, and restrict maximum rail pressure to a maximum value.



more detail in TDR issue #47, soon to hit the streets, but basically this pressure relief valve is not designed to be used. when it pops, its ability to re-seat and maintain rail pressure may be compromised leading to eventual failure of the device and an expensive dealer repair.

 

[yycguy]

when it pops, its ability to re-seat and maintain rail pressure may be compromised leading to eventual failure of the device and an expensive dealer repair.

Dleno, Thanks for the great post, I as I mentioned in previous post I had the Predator stage 3 box, the performance was great, but I was scared of the relief valve issue and took the box out. Not that I intend to run the Predator again but I am curious why is replacing the relief valve a big job? where exactly is it?

Thanks again

 

[DLeno]

I don't think its a matter of technical difficulty, its a matter of the control placed on that component, and the act of congress you have to go through to get it replaced. you can't buy them, and it takes a STAR line approved warranty case at the dealer to even get one. thats what I was told anyway.



some of that control is for good reason. they don't want just anyone replacing a component of a 23,000 PSI fuel system.



The valve is located just to the firewall side of the rail pressure sender, on the drivers side of the engine. all pressure boxes hook up to this pressure sender, which is just on the firewall side of the intake air pipe from the intercooler. The pressure relief valve has a banjo bolt on the top that carries fuel from the high pressure rail back into the low pressure side of the CP3 intake.



there is a picture of it in TDR #47. I wish I could tell you when that will be mailed out but I can't

 

[Ron Civita]

DLeno:



Thanks for that great post. I now have a better understanding of the rail pressure system and pop-off valve.



I really enjoy TDR and the volumes of information available from folks such as you.



Can't wait for issue #47.



Thanks again, Ron

 

[yycguy]

Thanks again for the great info, I have a Friend that I mentioned earlier in this thread that had his blow (2X) and the service dept told him the cost to replace was $1500 a pop. (ooch) So I don't want to go their!