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Discussion Starter #1
can you please explain how the boost is controlled on the car ?

someone told me it is regulated by the weather so is always runs the same boost, is this correct ?

any and all input would be much appreciated
 

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Discussion Starter #3
cali said:
Tell us what does yours do?
what do u mean ?

just trying to figure out how my boost is regulated, so far i guess no one else on here knows.

another friend of mine one has a one and says there is some way to turn up the boost, so which is it ? weathe controlled or can it be changed ?
 

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boost

Hmmm.
Yes, and yes.
Yes, weather can play a part in how much boost you make.
Yes, you can regulate your boost.
No, I wouldn't recommend you do it just yet. Read up some more on
turbos, first. Look around the board, talk to people. Learn or burn.

(did that sound harsh?)
 

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I'm not going to go into it there are to many factor to name, read this (What I could find on short notice) and ask your questions from there.

http://www.grapeaperacing.com/GrapeApeRacing/tech/turbocams.cfm -James
 

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Discussion Starter #8
so there is nothing special about the SRT 4 setup as far as boost control and weather ?

I have heard this a few times already and was wondering if it was true ?

thanks !
 

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Yes there is,
The weather changes everyday with different temps and different atmospheric pressures. The computer trys to compensate for these changes to bring out the best in the car i.e. factory claimed hp and tq.

-James
 

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Also altitude, and air pressure. Thats why I run 12psi down in SoCal, and 15-16psi up in Pheonix. The ECU adjusts the boost to keep the power level constant.
 

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I know there is some speculation that the computer was programmed to maintain a certain power/torque level, but I have to strongly disagree. That would be a very complicated task. Yeah, I like the car, yeah, it's fun and impressive, but it ain't no V-10 Formula 1 racer, folks.

And as far as boost being controlled by the weather, :roll: NO! Does temperature have an affect on boost response? YES. Forced induction engines will boost faster when they are sucking in cold, dense air. Sometimes boost even rises so fast that you can spike into overboost range. It's not unusual to see your boost respond differently with different air temps, but the computer operates by information it receives from the sensors on the engine, not by the weather.
 

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Another issue:
"Why am I only getting X psi boost in 1st gear, but I get Y psi in 3rd gear?"

Again, this is not something unusual and there is nothing wrong with your car. No, the SRT-4 does not have the world's smartest super-computer under the hood. :cry:

The answer has to do with how much the engine is being loaded down. It's the same reason why you won't see any boost when you rev the engine with the trans in neutral. When the engine is loaded it requires more fuel and air to make enough power to handle the load. Put a load on the engine, for example, pulling a trailer with a boat on it, or going up a steep hill. You mash on the accelerator to keep speed up. The engine wants more air and more fuel, exhaust flow and temp go up, boost comes on faster. The computer is not controlling the boost as much as the exhaust is. The computer will limit how high the boost can go, but that's about it.

Find a steep hill near you and try it. Put it in 2nd or 3rd gear going up the hill and stomp on it. Now do the same thing on a flat, level street. Boost response will not be the same.
 

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Mike B. said:
Another issue:
"Why am I only getting X psi boost in 1st gear, but I get Y psi in 3rd gear?"

Again, this is not something unusual and there is nothing wrong with your car. No, the SRT-4 does not have the world's smartest super-computer under the hood. :cry:

The answer has to do with how much the engine is being loaded down. It's the same reason why you won't see any boost when you rev the engine with the trans in neutral. When the engine is loaded it requires more fuel and air to make enough power to handle the load. Put a load on the engine, for example, pulling a trailer with a boat on it, or going up a steep hill. You mash on the accelerator to keep speed up. The engine wants more air and more fuel, exhaust flow and temp go up, boost comes on faster. The computer is not controlling the boost as much as the exhaust is. The computer will limit how high the boost can go, but that's about it.

Find a steep hill near you and try it. Put it in 2nd or 3rd gear going up the hill and stomp on it. Now do the same thing on a flat, level street. Boost response will not be the same.
Mike, I installed an EBC in my car and whatever I set the boost to is what I get in every gear. How can you say that the stock solenoid is not controlled by the ECU?
 

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If you have a boost controller that's different, of course. In my post above I was just talking about stock stuff--no mods.

I'm not saying that the computer doesn't control the solenoid. I was trying to say that in a "high demand" situation, like going up a steep hill, response is going to be faster because the engine is working harder. But yes, the computer/solenoid still slows down response (compared to having a EBC or MBC) and controls the boost limit.
 

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Hey guys. Just so you know, there is ONE thing I know of that IS controlled by the weather. If by weather you mean the barometric pressure. Fuel cutoff is directly related to atmospheric pressure. There's a formula that states fuel cutoff will occur when the atmospheric pressure + boost pressure = a specific number.

I'm pretty sure I can give out the "exact equation." Let me look it up and I will post it. If anyone else knows the exact equation for fuel cutoff, feel free to post it.

-Sam
 
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