spooling a T66 turbo with a stock D-5 converter

[evil666]

This question is for Jason or anybody that would be able to anwser it. I am really interested in the RJC boost controler but I am still confused about it. I just don't get it, does it mean if I have the boost set up for 24 lbs on the controller and I slowly bring the gas pedal down I won't be seeing any more low boost like 1-2-3-4 and so on. Does this mean the boost will come in, in one shot at 24 lbs, basically 24 lbs of boost or nothing. If this is the case it must be pretty insane to control tire traction on the street with all that boost comming in at once. My other question is how will this RGC BC work when I am boosting off the line. I bring the boost up to about 9lbs by foot braking off the line, and this really confuses me because does this me I won't be able to get boost off the line unless I planning to come off the line at 24lbs. This would cause 2 problems for me: One would be I wouldn't be able to hold 24 lbs of boost off the line on foot brake, the other problem would be if I would be able to hold 24lbs and I would let go of the brakes I would come up in smoke. I will thankful if anybody could answer my questions.

Thanks
Marco

86 Grand National t-top (59000km)
stock long block,stock suspension, red stripe convertor, te44, smc alk injection, 24lbs boost, 94 octane, hooker cat back with dyno max ultra flow muffers, tomco 30lbs injectors, dynotech stage 4 street chip, thdp, mease 24 row IC, MT drag radials (275/50/15) 3800lbs race weight with driver.
best ET
60FT=1.52
1/8= 7.38
I/4= 11.74
MPH=113
BEST MPH= 114

 

[turbo2nr]

Your wastegate will open before your target boost setting with the OEM set-up, or most other boost control devices. Spool-up could be quicker on most turbo cars. Sure you, and everyone can figure out how to get X amount of boost, but what if you could get it faster? The only other way to achieve this is with an expensive electronic unit with "brains". RJC is trying to keep wastegate closed untill the last possible moment, when your target boost is reached. Takes a while to think about the forces at work here.

 

[jjvites]

Evil666,
Just for example lets say that your car takes 2 seconds to get to your 15 lb boost setting from the time you floor it. Well now it might only take 1 second because the RJC valve wont allow the factory electronic waste gate solenoid to open the waste gate puck slightly as it is designed to do. The factory waste gate only starts working after your setting in the RJC valve is reached. So the answer to your question about all boost at once is NO. Same progressive boost but much quicker.

 

[2QUIK6]

Originally posted by jjvites
Well now it might only take 1 second because the RJC valve wont allow the factory electronic waste gate solenoid to open the waste gate puck slightly as it is designed to do.

As programmed from the factory that is correct, but most aftermarket chips bleed 100% so that it takes more than 12-15# to actually start opening the wastegate with the factory solenoid setup.

 

[jjvites]

2QUICK6,
You know more about aftermarket chips than I do so I am curious and in no way being a smart ass but why is that when I used Red Armstrong chips, Thrasher, and long time ago a Pit Bull chip that I DID NOT have instant boost to 15+ psi like I do now using the
Bst Commander. I would compare this to having the waste gate hose removed from the acctuator and that instant boost that you get because the waste gate is not being used. It seems to me that there must be SOME bleed off even in the aftermarket chips or it's delayed. Otherwise there would be no difference between the aftermarket chips and the RJC valve or Bst Cmd. Yet people here on the board and I have experienced that it greatly reduced the boost time. What do you and others think is happening?

 

[BoostKillsStres]

jjvites,
The stock code, in basic short terms, causes the wastegate solenoid to slowly start to bleed whenever the ecm "thinks" your in boost then slowly bleeds more and more until the final bleed/boost value is reached. So you end up with a nice 1/2 bell shaped curve of the bleed percentage as it comes in if you look on a Directscan log.

This causes the WG diaphram to see some boost early on and thus it will unseat the WG puck some as the whole boost control curve is ramped in and thats why spool is slower because the puck isn't staying shut like when using the boost commander which bleeds off 100% so the puck doesn't move or the RJC setup which prevents the puck from seeing any boost until your close to your final boost value.

HTH, not to steal the explanation for you from 2quick6 but just thought I'd throw a quick explanation out there w/o getting into wg coefficients and boost per rpm tables and such. And it of course depends on what the chip vendor did in the chip to try and get fast spool with the stock setup. You can only bleed 100% for so long for faster spool then you'll start getting into transitional knock when nailing if from low speeds and going into high loads on the engine with the stock setup.

 

[jjvites]

2QUICK6,
You know more about aftermarket chips than I do so I am curious and in no way being a smart ass but why is that when I used Red Armstrong chips, Thrasher, and long time ago a Pit Bull chip that I DID NOT have instant boost to 15+ psi like I do now using the
Bst Commander. I would compare this to having the waste gate hose removed from the acctuator and that instant boost that you get because the waste gate is not being used. It seems to me that there must be SOME bleed off even in the aftermarket chips or it's delayed. Otherwise there would be no difference between the aftermarket chips and the RJC valve or Bst Cmd. Yet people here on the board and I have experienced that it greatly reduced the boost time. What do you and others think is happening?

 

[jjvites]

BOOSTKILLS,
Thanks, that's how I understood it as well by my answer to Evil666. But now my question was to the response by 2QUICK who stated that aftermarket chips bleed 100% and that would negate the RJC valve as pointless, which I don't think that it is.
Again this is not a smart ass response or challenge, just conversation.

Marty

 

[2QUIK6]

Originally posted by jjvites
BOOSTKILLS,
Thanks, that's how I understood it as well by my answer to Evil666. But now my question was to the response by 2QUICK who stated that aftermarket chips bleed 100% and that would negate the RJC valve as pointless, which I don't think that it is.
Again this is not a smart ass response or challenge, just conversation.

Marty

I can't say that "all" do this, but a few that I've looked at do, and some don't. The factory did not do this because they didn't want quick boost to fry the skinny stock tires off and cause the car to be uncontrollable, and depending on the turbo and convertor combination, this may be a good feature to keep in there. For my setup, I have set the WG bleed and scalars to bleed off all the boost possible, and then let the BstC commander to control the boost over what the chip is programmed to do.
As Mark points out, the stock solenoid can only bleed so much boost even at 100%, my guess is that around 10-12#, even with the solenoid bleeding 100% that boost will start making its way to the actuator and opening the puck.
There are many other variables that may effect spoolup, mainly the A/F ratio and timing...during spoolup, if you can get the EGTs up during the "spoolup" time, spoolup will be much quicker.
Spoolup of my GT61 with a 2700 convertor is very noticable if you do not have the perfect tune. All I'm saying is I did not notice any difference with the RJC valve than with my own custom tune....thats not to say that the RJC would not help with a slightly off tuned motor that may be rich at spoolup, or some over the counter chips that do not bleed 100% of the boost at low rpms.
Also the fact that I want in cockpit controll of my boost, which I can't do with the RJC valve since it will not work in combination with the solenoid.

 

[BoostKillsStres]

Gotcha, jjvites well for another 2 cents worth, in the stock code you can really only bleed 100% upto about 2800 rpm then you run into too much boost when getting into it on the highway as 2800 rpm is pretty easy to hit before getting to wot and still being in a higher gear w/ a lot of load which will cause knock. But with the RJC valve it only cares about boost so its not limited by rpm. So it would seem it can do a better job at spooling the turbo under all conditions. Now I don't have a BstC so I assume it can only bleed the stock solenoid as the same rate as a chip, 100% . Does the BstC have a boost reference hose going to it? If it does then it can also bleed 100% for a wider range than the stock rpm limited chip setup.

I haven't had the time to test my rjc type setup against my fast spool chip code yet but still plan to and since I'll be logging boost on Directscan I'll have plenty fo data to really see which is faster. Just too many things going on to play with the car right now.

Anyway, from driving w/ the rjc type valve I'd have to guess its spooling faster than the chip code but I just don't have any data yet to prove that with the controller types being the only variable in the equation.

 

[jjvites]

Good info guys, always good to learn more.
The Bst does not use boost reference hose.

 

[2QUIK6]

Another thing to factor in is the individual turbo. Some spool lightning fast from 10-20# while it may take time to get it to that initial 10#, while others spool to 10# very quick, but 10-20 may take longer. Mine goes from 10-20 very quick compared to 0-10, so the benefit of the RJC not bleeding any boost up to about 18# compared to the solenoid bleeding off some boost after the intial 10-12 may be of no noticiable difference since the turbo I have spools very quickly already after the initial 10#.