newbie type question re: boost control

[msaskin]

Well, this may be a newbie type question, and may be in the wrong section, but here goes:

coming from the world of other turbocharged cars (primarily the 3000GT/Stealth and DSM platforms), the one thing everyone cares about is a boost controller. On those cars, the stock boost solenoid does nothing but maintain boost...it doesn't compensate and lower boost when the ECU detects knock, so most people just use a boost controller, be it manual (bleeder valve, etc...) or electronic (any of a # of expensive units).

my question is, why is no one in the SyTy world (so far as I've seen) using a boost controller? It is my understanding that the ECU can drop boost based on it reading knock...right? If so, does everyone just let the computer control boost (and raise it via different chips, etc...)

Simply answers or technical ones would be appreciated...

~matt

 

[TY#1924]

boost

boost

sent you a PM

 

[ghettosled]

everyone who uses the ultimate chip has built in boost control(5 different boost levels to choose from, and 3 timing settings). Anyone running an external wastegate must use a stand alone boost controller be it electric or manual. I would say many of us are using some sort of boost control, b/c ultimately raising the boost is what is going to make more power. SOme just choose to run a high pressure wg actuator, or adjust the factory wg rod (it is already threaded). BUt the remainder do it through the chip, or with another type of controller.

You are correct that when the ECU detects knock it will pull timing which as a result will pull boost. Using a scan tool to fine tune the truck will allow you to eliminate the knock retard and run more boost. You dont want to force more boost into the truck if it is knocking. It pulls back for a reason.

 

[msaskin]

You are correct that when the ECU detects knock it will pull timing which as a result will pull boost. Using a scan tool to fine tune the truck will allow you to eliminate the knock retard and run more boost. You dont want to force more boost into the truck if it is knocking. It pulls back for a reason.

So what you're saying is that the ECU doesn't pull boost directly, it's just the less power from pulled timing results in lower (at least, relatively lower) boost levels?

I'm just used to the ECU having basically nothing to do with boost control, so it necessitates using a boost controller (be it electronic, manual, whatever), much like the setup on SyTy's when you go to an external gate.

~matt

 

[dgoodhue]

Another issue is the stock turbo has problems with boost control (getting steady boost is practically impossible with the stock internal wastegate) Adding an aftermarket boost controller to the stock turbo usually creates boost spikes (and can destroy the motor)

Also with a little bit programing you can also modify the stock ECM programming boost control. Unlike Japaneese cars, GM ecm are pretty much fully programable, you don't need expensive piggy backs or to buy black box ECM's where you have idea what the tuner really did.

 

[InvisiBill]

Ghettosled isn't quite right about needing to run a separate boost controller with an external wastegate, I don't think. This is theory, based on lots of reading and discussions with Brian Green (the guy who does the code for the Ultimate chip).

If you had an external wastegate that matched the stocker's characteristics, you should be able to move the vac line from the stocker, seal it shut, and put the vac line on the external. The external would need to have the same base boost level and everything. In the stock setup, the base boost is around 8-10psi. Ideally you want base boost as close to your target boost as possible, for best boost control. To make an external with stock, you'd have to set it up with relatively poor settings. The only thing you'd really be improving over stock is the flow out of the wastegate (which does suck on the stock setup).

The stock internal wastegate has to make a 90 degree turn to flow back into the downpipe. If you have a slightly modified downpipe, you can punch out a little service port cover on the back of the turbo. This gives the wastegate a straight shot into the downpipe, which is said to alleviate most of the problems associated with the stocker. Pictures 3 and 5 in JS's DP gallery at http://jsman.huryde.com/gallery/3dp show the extra part that needs to be added to the downpipe. The top part of the turbo is the main exhaust outlet, and the little angled part below covers the service port and catches the exhaust coming out of the wastegate. As was stated, trying to do fancier stuff with boost control can easily lead to boost spikes, since the stocker just can't flow enough exhaust. You should do something about the wastegate itself before trying to monkey too much with boost control.

 

[ghettosled]

Ghettosled isn't quite right about needing to run a separate boost controller with an external wastegate, I don't think. This is theory, based on lots of reading and discussions with Brian Green (the guy who does the code for the Ultimate chip

I have heard rummors about people testing it, but as far as I know nobody has anything readily available (chip wise) and has proven it to be a success with no hickups. I'm sure it is possible, but 99% of the people dont know or have the resources to do the ecm mods like BG and some are capable of. SO basically until somone comes out with a plug in play chip to control the externals like the ultimate chips did with the 3 bar map, then I will just say you need an external boost controller to go with the external wastegate.

 

[Syclone#1992]

I have an TIAL 35MM external gate with a Blitz boost controller. I have a stock turbo and have found this to be the most accurate boost control. I wanted something cab, that was adjustable on the fly. Blitz has 3 boost settings and has a gain setting that controls how fast the turbo spools. When you start turning the gain up a little higher you may get a 1 PSI spike at shift points. For the most part I am really happy with the Blitz setup. Boost can be set up to be instant. By far one of the best mods done to my truck.

 

[InvisiBill]

I have heard rummors about people testing it, but as far as I know nobody has anything readily available (chip wise) and has proven it to be a success with no hickups. I'm sure it is possible, but 99% of the people dont know or have the resources to do the ecm mods like BG and some are capable of. SO basically until somone comes out with a plug in play chip to control the externals like the ultimate chips did with the 3 bar map, then I will just say you need an external boost controller to go with the external wastegate.

Again, this is all theory, and may very well be completely wrong. But in talking with BG (he puts up with a lot of my clueless babbling for some reason), it seemed that he agreed with me that it should work. If I understood right, it shouldn't require any chip changes.

Your external would have to have the same ~8psi base boost, to coincide with the stock chip (which is calibrated to the stock wastegate). Move the vac line from the stocker to the external and seal the stocker up. As I said, you'd still have your base boost way below your target boost, which isn't optimal. It would literally be set up just like the stocker, but should flow a lot better. The flow of the stock wastegate seems to be a big part of the problem, as the Christian Dionne/JS-style opening of the service port seems to give the stock wastegate (with no other changes) much better control.

A separate boost controller will obviously work better. I was thinking of using an external wastegate with stock control as sort of a stepping stone so you didn't have to buy everything at once. Later, buy the controller and a different base spring, and it's even better.

I'm not saying that BG told me this. I'm saying that this is how I think it will work, if BG understood me correctly, and I understood his responses. It seems logical to me that it would work this way.

 

[ghettosled]

if it works, let us all know.