I know there are several clever boost control devices out there, but don;t know which are the best.

I have the stock, Buick Waste control, which an adjustable actuator rod that pushes the waste gate open. In an attempt to lower the boost last night, I lengthened the rod, which is the way it is supposed to work. The upper boost did not change,but boost did come on a tad later, which I am actually OK with. But, I dont; want it any later than it is now, and the boost is rising to 10 lbs. I know have been saying it goes to 9, but preignition is now light enough that I felt I could red line it a few times, and the boost gets up higher than I used to think it did.

I would like to get better control over this. I could join turbobuicks.com, but I would like to tap this brain trust first. Any experience or opinions?

Sam

_________________

I have an RJC aftermarket boost controller that works with the "factory unit". I have a factory HD unit that allows 17psi when set at the factory specifications. The aftermartket controller allows me to turn the boost up (21psi now) without messing with the factory can's settings. It sounds like you have a standard factory unit and the Buick guys should be able to identify it for you.

The problem with the factory units as I see it is their inability to be adjusted...meaning the can is sealed and you are unable to change the spring pressure (in the can) that controls boost.

As you have discovered, you can delay the boost coming on by lengthing the rod but it will not change the max boost that the "can" can deliver.

I never looked but there may be an aftermarket light duty stock style wastegate. This would work good in conjunction with an after market controller, thus giving you the ability to start low and work up.

How did the car feel with WOT?

The Drakes originally used the Turbonetics "Deltagate" and now use the "Racegate," both of which work fine. These are external and adjustable and are the way I will go. I will use a deltagate.

Lou

_________________
Home of Slant6-powered fun machines since 1988

Link to the boost controller I use. Recommended by one of the buick guys.

The one that Lou mentiond above is an external wastegate and $299.00. Overall the external wastegate may be better at managing the boost. Since Sam is using a stock TBO348 off of a GN, I assume he is still using the integral wastegate like me. The below wastegate by RJC works with the stock wastegate and is $50.

http://www.rjcracing.com/

Look for this one coming soon. It has 4 channel memory and is adjustable on the fly.





Mike

_________________
Recognized by US Federal Courts as a Fuel Economy Expert!

Mike, Can you tell me more about this? I clicked the link, and wasn't sure what I was to do from there. How does it work? Is it electronic? How does it function. Who makes it? When do you think it will be available? Roughly how much will it cost? Thanks, Sam

_________________

When you open up the exhaust and and intake on a Buick they start having boost control problems. It just starts climbing in third gear and / or spikes on the shifts. It sets off the knock control and it is like the engine shuts off.

So since you are using a stock buick gate, the cheap but very reliable fix that works for this should help you.

You need to open up the waste gate hole in the turbine housing. .9" is a common size. Just remove the turbine and waste gate housing and scribe around the round wastegate puck in there or see if there is a carbon outline already. The hole does not usually line up very well so you need to center your larger hole with the door. Find a socket or something round of the right size and scribe for you enlarged hole. Open it up and radius the inside with a die grinder. You can clean up the exit of the waste gate housing where it dumps out while you are at it.

This will allow you to run the actuator tighter which will get the boost up quicker, but will lower the boost at the top end and make it more stable as well.

I would not waste my money on an electronic boost controller as long as it can be worked out with the simple mechanical parts. With the Grand Nationals I have seen quite a few cars with all sorts of magic electronic boxs and valves and hoses. They were never the faster cars. It's just more crap to deal with and another failure point. Leave it to the rice burners. Once you get this sorted out, there is really no need to change boost from the cockpit, unless you use an electronic octane controller too.

Thanks for the advice on dialing in the wastegate door fit. I will likely do that at some time. But, I would like to lower the boost for initial tuning to around 6 lbs. And then bring it back up and tune for it as I increase the boost back up. Is there not a simple way to do for this? In the past someone talked about an adjustable mechanical valve in the boost line that you could open and close to vary the upper limit to the boost. I'm sorry I don;t remember who mentioned this, and never truly understood how it worked. Maybe I misundersood completely, and imagined something that is impossible.

FAstest is not necessarily the goal here, but more flixible tuning is. Everything in this tuning package can now be adjusted, except the boost, and it seems as if playing with that might be useful in the big picture.

Given a fixed engine and exhaust configuration, and a fixed turbo and housing , is the wastegate the sole determiner of when boost comes in, and how high it will go? Is it possible to limit my combination to just 6 lbs of boost? I am trying to imagine how this would work, and it seems that if the waste gate is fully open, then you cannot open it any further and reduce the pressure any further. Is my mental concept of this right?

Sam

_________________

The way I understand it, the housing determines when the boost start, and the wastegate limit the maximum pressure...

How about trying a spring from the little arm going out of the housing?
it would make the wastegate spring seem weaker...right?
Then you could use the boost controller to add boost when you want it to.

You likely cannot get the boost that low with the stock buick gate. Like you already know, you can only turn it down so far before it is open all the time. Even then it just is not sized to run such low boost. Turbine housings affect the boost levels, but the total flow verses waste gate flow is what is getting you in this case. Adding an electronic controller cannot make the wastegate flow more. They are only able to increase the boost above the gates minimum setting. You can do the same thing with a needle type bleeder valve teed in to the waste gate line.

From what you have said you clearly understand how this works, but were not 100 % sure. Like many things there are misconceptions about how these work, and ideas like fancy boost controllers fixing everything fall into this area. The Buicks waste gate was considered computer controlled but it was just a solenoid that was pulsed to bleed off some pressure to the actuator so the boost would rise to the normal setting of 13.5 psi. When the knock sensor signal became strong enough and pulling back the timing was not enough the computer shut off the solenoid and the boost dropped to the waste gates mechanical setting which was about 10 psi.

The stock actuator in good shape works well between about 10 and 15 lbs. with the stock sized hole. Higher than that and an actuator with a stiffer spring is needed for stable control. That is what I had on my GN. Of course these are available since higher boost is a common goal. I don't know of a lower rate actuator, but there may be one. Adding an external spring may help lower the rate, but you will still need more flow.

Just for the record. The stock Buick waste gate actuators did NOT have an adjustment on them. It was very common to cut the end off and thread it and put a female eye on to make it adjustable. You could have a stock one modified this way, an actuator that came with a rebuilt turbo, or one of the higher rate actuators that ended up on thousands of those cars.

I would open up that hole as much as reasonable and it very well may get you what you want with the stock actuator, if thats what you have. Thats really all you can do to increase the stock gates flow.

It is important to keep that gate closed until the boost starts to build and then have it open before it spikes, so you do want some tension on there. You can do some fine tuning with restrictors in the line to slow the gates opening too, if it is otherwise where you want it but opening a little too quickly.

One of the larger external gates would definitely work. Aside from the adjustment they have different springs for different boost ranges. They are, as already pointed out, rather expensive.

Thanks again. I put this adjustment on myself based on an article published several years ago on Turbo-Buicks.com At the time, I did it because the article made sense to me, and it was a very simple mod.

Sam

_________________