snowboard49dude

Thanks alot!!!! I really appritiate it

Fobra

for a stock motor - supercharger for a built motor - turbo... for a fun drag/race car - turbo are tops, for a bracket racer - supercharger

FoxGT

I know what causes it. Once you reach boost threshold, boost shoots up incredibly fast & can sometimes go past what your boost is set at, then settle back down. I know that cold days make the air more dense causing it to happen faster. What i'm saying is your wastegate should be opening to vent off the exhaust gasses to keep it from happening. Either your vac line going to the wastegate is too long or your boost controller is junk. spikes aren't a problem when properly set up. I know it's a problem with some stock turbo cars, but it can be fixed.

OneFastEclipse

You clearly don't seem to know what causes it. A spike happens before the wastegate even has the chance of opening. Thus the reason the boost settles back down after it does open. A boost controller isn't even necessary on a turbo setup with a proper wastegate. Spikes can and will happen regardless, some setups more drastic then others. Boost creep on the other hand usually has to do with a malfunctioning or inadequate wastegate.

FoxGT

I'm sure we could throw the not knowing what we're talking about all day still comes down to the same thing. I've had quite a bit of experience in building kits & for all i know you could own a company. Not that I'm doubting you know what you're talking about, any possible way you can show me something to prove that it has nothing to do with it? & I don't mean just one source from someone that owns a car.
I can probably find about 30 sources saying it has everything to do with opening the wastegate, either there being a buildup causing the wastegate to resist opening, too long of a signal line, boost control solenoids (which opens the valve to let pressure to the wastegate actuator) sticking. The only reason I know about it is because I had a spiking problem with a kit i built about 4 years ago, so talked to quite a few companies about the causes of it & what could be done to fix it. I personally don't like going to just one company about a problem in case they dont know & pull an answer out of their *** so I'll ask multiple companies before I try what they suggest. Considering I've had a big problem with it & after gathering quite a bit of information fixed it I know from experience that I've fixed it on at least one of my kits & haven't had a problem with it since probably just from that experience alone.

consider how many cfm your engines flowing & how fast the air is going to move to shut the gate (unless you have a 1lb gate which no company in their right mind uses a super heavy one). I don't know of one properly set up turbo system that has a problem with spiking.
I know a boost controller isn't required, but it can be a cause of spiking & a good boost controller can help eliminate the problem on a stock setup or a poorly built aftermarket one.

creep and spike both have alot to do with the wastegate. but creep is caused by a completely different thing than spikes. If it would help in the future I could even email a couple of major companies & we could wait a few days to see what they say about it.

snowboard49dude

ok so Eclipse...you went supercharger and how is it treating you? like are u getting what u need out of it? and what kind do you have?
And Fox...do you have a supercharger or a turbo?

FoxGT

turbo on my notchback & currently building another twin turbo kit for the '89 Gt. Built s/c kits, but have only owned turbo/tt cars.

OneFastEclipse

Well, I can't say that I own a company (though it would be nice!) but I do have lots of experience when it comes to turbochargers. Basically, if you are having a issue with boost spike right from the get go after you install a kit and can not get it to go away, then yeah I could see what your saying may help by making the wastegate actuator more sensitive. That's not the issue I'm talking about though. What I am referring to is when you have a turbo setup on a car, it's been tuned and perfected at one temperature, we'll say 80 degree summer weather, and then say fall weather comes around and now you have 50-60 degree temps. With that kind of change in climate, the change in air flow is drastically increased and it can cause boost spike and in some instances, boost creep as well. I guarantee anyone that has ever owned a modified turbo car has seen boost spike and/or creep at least one time in their hobby, some more severe then others. It's just something that comes with setup.

@Snowboard49dude Should you not buy a turbo system simply because of this? Absolutely not! Turbos are a awesome way to make huge power numbers. Just remember, "With great power comes great responsibility" (I love that quote ). You have to be willing and prepared to make changes on your tune and setup when needed with your turbo system. Either that or make everything real fat and conservative to keep it safe.

I absolutely love my supercharger setup. It is a Vortech S-trim and I am running methanol injection along with it. It is a totally different feel then a turbo and produces plenty of power. Hopefully I'll get it to the dyno within the next month and see exactly what I can get out of it. Shooting for between 450-500rwhp. The weather finally started to get nice around hear so after I finish moving into my new house, I can go ahead and finish everything I been meaning to finish on the car for the past 6 months.

FoxGT

I guess I just dont see it. I don't understand what the tune has to do with the manifold pressure opening & closing a valve. While tuning has to do with air/fuel ratios & ignition & boost has to do with the pressure or vacuum in the intake altering the condition of a valve. I don't see how a tune could slow down the effect of the wastegate even with a horrible tune or a tune perfected for a certain temp (which I don't understand why you would tune it for a certain temp when you could include an intake air temp sensor to alter the tune under those conditions) They're two systems that have nothing to do with eachother, one being pressure controlled, one being electronically controlled (in most cases). Even if you went with a solenoid to control boost to have a lower boost threshold.

Who are you talking about that had this problem? Someone on the forum, if so I could talk to them & see what's up with their setup. I don't see it happening unless something was done wrong. I dont get why that person would tune the car for a certain temp either rather than include it unless they overlooked the feature or got a bad tune.

OneFastEclipse

Your problem is your trying to look too far into it. The tune has nothing to do with a boost spike. The change in temperature does! If you take a car that is setup to run 8lbs of boost at 80 degrees, don't change a thing and put the same car in 50 degree weather, it will make more boost, weather it be through a spike, creep, or a little of both. This in turn can make your tune that was perfected on a specific cylinder pressure lean. Obviously you can correct this by adjusting your boost controller, wastegate, whatever, but not everyone wants the hassle of that. Simple solution, run the whole tune a bit on the rich side at 80 degrees so when the temp drops, you won't start to run lean.