Chip can't increase boost?
Discussion
Can boost be increased just by changing the chip? I have the high torque chip from Sanj and I show 1 bar of boost as opposed to 3/4 bar before the chip. Well, while talking to a Lotus shop and explaining some things I am interested in doing, they advised "boost can only be increased mechanically" when I was briefing them on what has already been done to the engine. So whats the truth?
John
94 S4
www.skynetworks.gotdns.com
John
94 S4
www.skynetworks.gotdns.com
I am the least mechanically inclined on the list but I think I can explain how it works real quick:
Boost pressure is controlled directly (mechanically) by the wastegate which receives pressure through a line from the manifold. The spring in the wastegate is set to open at a certain pressure, let's say .65 bar, but obviously since it is mechanical it will start to bleed before it reaches .65 and finally be open all the way when it hits .65.
In order to control it more accurately a solenoid is put between the line from the manifold and the waste gate, a proxy if you will. This solenoid is controlled electronically, buy the ECU, and holds back pressure until it senses a certain “boost” has been reached in the manifold (whatever the ECU is telling it to look out for at any moment in time) and then opens and blasts pressure at the waste gate all at once overwhelming it and causing it to open all the way.
This system makes the wastegate "digital" or "on/off" as opposed to being a gradual bleed and also allows electronic control over “boost .”
The pressure the wastegate spring is set to open at and the desired max boost pressure in this system have nothing to do with each other at all.
Does that make sense?
Luke.
Boost pressure is controlled directly (mechanically) by the wastegate which receives pressure through a line from the manifold. The spring in the wastegate is set to open at a certain pressure, let's say .65 bar, but obviously since it is mechanical it will start to bleed before it reaches .65 and finally be open all the way when it hits .65.
In order to control it more accurately a solenoid is put between the line from the manifold and the waste gate, a proxy if you will. This solenoid is controlled electronically, buy the ECU, and holds back pressure until it senses a certain “boost” has been reached in the manifold (whatever the ECU is telling it to look out for at any moment in time) and then opens and blasts pressure at the waste gate all at once overwhelming it and causing it to open all the way.
This system makes the wastegate "digital" or "on/off" as opposed to being a gradual bleed and also allows electronic control over “boost .”
The pressure the wastegate spring is set to open at and the desired max boost pressure in this system have nothing to do with each other at all.
Does that make sense?
Luke.
Hi John, Hi Luke,
Luke has explained it already very well ...
The machenical wastegate setting on all Delco-ECM 4-Cylinder Esprits (MY88-MY99) is exactly 0.65 bar. Everything above 0.65 bar is done via ECU. The ECU controls all boost from 0.65-1.25 bar. This is done via PWM-boost-solenoid-valve. The tables for boost control are actually stored inside the chip. You see boost control is done by the chip !
Thats why all the different chips #0 - #7 have different max. boost ;o)
Cheers
Marcus (www.PUKesprit.de)
Luke has explained it already very well ...
The machenical wastegate setting on all Delco-ECM 4-Cylinder Esprits (MY88-MY99) is exactly 0.65 bar. Everything above 0.65 bar is done via ECU. The ECU controls all boost from 0.65-1.25 bar. This is done via PWM-boost-solenoid-valve. The tables for boost control are actually stored inside the chip. You see boost control is done by the chip !
Thats why all the different chips #0 - #7 have different max. boost ;o)
Cheers
Marcus (www.PUKesprit.de)
karmavore said:I believe the solenoid actually applies a vacuum to the capsule.
This solenoid is controlled electronically, buy the ECU, and holds back pressure until it senses a certain “boost” has been reached in the manifold (whatever the ECU is telling it to look out for at any moment in time) and then opens and blasts pressure at the waste gate all at once overwhelming it and causing it to open all the way.
It also seems capable of handling things pretty gradually though I suspect it does it by playing a tune on the solenoid. Marcus can correct if I'm mistaken, but there's a pretty elaborate boost map that takes part throttle into account. IOW, the wastegate isn't always closed just because you're under 1 bar.
(You might be saying exactly that and I'm reading it wrong.)
techspy's Mechanics said:
"boost can only be increased mechanically"
I think I would look for a mechanic that was more familiar with the system he was working on. While they may be OK for things like alternators or even a clutch job, I would not trust such a wrench on anything involving the computer system.
Dr.Hess
Mikey,
The capsule is NOT actuated via vacuum ! Its actuated via positive pressure (boost).
The solenoid is acting like a ECU-controlled bleed valve. When boost more than 0.65 bar is desired the solenoid is partially bleeding away boost from the capsule and therfore is holding the wastegate more closed ---> more than 0.65 bar boost is generated
Cheers
Marcus (www.PUKesprit.de)
The capsule is NOT actuated via vacuum ! Its actuated via positive pressure (boost).
The solenoid is acting like a ECU-controlled bleed valve. When boost more than 0.65 bar is desired the solenoid is partially bleeding away boost from the capsule and therfore is holding the wastegate more closed ---> more than 0.65 bar boost is generated
Cheers
Marcus (www.PUKesprit.de)
Thanks guys. That’s what I thought. It really p%$#@s me off when Lotus "specialist" try to make you feel as though you are an idiot when it fact they are too full of themselves to see that they are wrong. I wont mention any names but it is a certain "specialist" on the west coast who gave me this info.
FWI, I contacted 2 well known shops by email to do some work on my 94 S4. Among other things a timing belt change and a turbo upgrade. It was obviously an opportunity for them to make a decent amount of money. One emailed back with some info and the other just asked for a number to call me, which I gave but never heard from him (the specialist). The first ones email did not instill any confidence. There was no punctuation and no capital letters. It was a fairly lengthy email but almost impossible to figure out what the guy was saying. I don't think I will trust my S4 to someone who can’t grasp basic grammar concepts, or to someone who doesn’t know that a chip can increase boost! What idiots!
Sorry, just had to vent..
John
94 S4
www.skynetworks.gotdns.com
FWI, I contacted 2 well known shops by email to do some work on my 94 S4. Among other things a timing belt change and a turbo upgrade. It was obviously an opportunity for them to make a decent amount of money. One emailed back with some info and the other just asked for a number to call me, which I gave but never heard from him (the specialist). The first ones email did not instill any confidence. There was no punctuation and no capital letters. It was a fairly lengthy email but almost impossible to figure out what the guy was saying. I don't think I will trust my S4 to someone who can’t grasp basic grammar concepts, or to someone who doesn’t know that a chip can increase boost! What idiots!
Sorry, just had to vent..
John
94 S4
www.skynetworks.gotdns.com
The reason I do virtually all my own work on all my vehicles (6, counting the bikes and the Locost) is that it is so hard to find a decent, honest mechanic. I knew of one place south of Houston that I would trust to not rip me off, but I don't live there anymore. They also just do "regular" cars, not exotics.
I did my first engine after paying someone else about U$3K over twenty years ago to rebuild the motor in my Europa TC Special. They took a year and screwed it up so bad that 15K miles later when I was holding what was left of #3 piston in my hand, I figured I could screw it up just as well myself and save a lot of time and money. I rebuilt that motor for about U$650 total, including extensive machine shop work (sleeves, turning crank, weld up the cracks in the head, new guides, valves, etc.) I have been doing pretty much all my own work since.
Dr.Hess
I did my first engine after paying someone else about U$3K over twenty years ago to rebuild the motor in my Europa TC Special. They took a year and screwed it up so bad that 15K miles later when I was holding what was left of #3 piston in my hand, I figured I could screw it up just as well myself and save a lot of time and money. I rebuilt that motor for about U$650 total, including extensive machine shop work (sleeves, turning crank, weld up the cracks in the head, new guides, valves, etc.) I have been doing pretty much all my own work since.
Dr.Hess
I agree. I try do do all the work myself. However, I havn't built up my tool chest yet and will be out of country for awhile and the Lotus will just be in storage. So why not use the down time to get a few things done? Fortunatly I do have a good shop that can do the work. He has pleanty of Lotus experience, just not so much with the Esprits. But, he does Lotus warranty work, so that is good enough for me. I just wanted to check all avenues before sending it to him.
John
94 S4
www.skynetworks.gotdns.com
John
94 S4
www.skynetworks.gotdns.com
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