Shimming wastegate...questions
04-30-2002, 03:45 PM
#1
Racer
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Shimming wastegate...questions
I have a boost enhancer set around 10 psi. I would like to shim my waste gate and add Autothority chips. I'm shooting for around a 3-4mm thick shim stack, but what are the proper ID and OD's for the shims? (Going to Home Depot...)
Also I understand that shimming the wastegate increases the pre-load on the spring. What actually regulates the boost level though? The cyclic valve, right? Does the chip set modify the CYCLIC VALVE REGULATED BOOST to 15 psi, or does it just adjust the fuel/timing maps and raise the factory boost cut-off? What I'm getting at is I need a reliable way to control the boost. The boost enhancer I have is not an LBE, but similar. With either model (from what I've experienced/read) you get some flash boost as the turbo increases speed exponentially, and there is some lag in the feedback loop. Point being I would like to use the boost ehnacer to reduce turbo lag, the chip set to faciliate higher boost levels, and then the stock cyclic valve to regulate the boost at 15 psi...am I missing something here? Many people control their boost levle with a LBE, but I don't feel comfortable doing that. Please fill in the gaps here for me....thanks in advance.
Also I understand that shimming the wastegate increases the pre-load on the spring. What actually regulates the boost level though? The cyclic valve, right? Does the chip set modify the CYCLIC VALVE REGULATED BOOST to 15 psi, or does it just adjust the fuel/timing maps and raise the factory boost cut-off? What I'm getting at is I need a reliable way to control the boost. The boost enhancer I have is not an LBE, but similar. With either model (from what I've experienced/read) you get some flash boost as the turbo increases speed exponentially, and there is some lag in the feedback loop. Point being I would like to use the boost ehnacer to reduce turbo lag, the chip set to faciliate higher boost levels, and then the stock cyclic valve to regulate the boost at 15 psi...am I missing something here? Many people control their boost levle with a LBE, but I don't feel comfortable doing that. Please fill in the gaps here for me....thanks in advance.
04-30-2002, 07:58 PM
#2
Race Director
As I recall, the washers I used were 8mm ID, OD can be anything really.
Since the spring-preload will be higher, you want to turn DOWN the LBE setting to get the same boost as before.
" Point being I would like to use the boost ehnacer to reduce turbo lag, the chip set to faciliate higher boost levels, and then the stock cyclic valve to regulate the boost at 15 psi...am I missing something here?"
The chips don't do anything with the boost other than get rid of the overboost-protection. Numerous people have tried to re-program the KLR to make the cycling-valve increase duty-cycle (and therefore boost) but to no avail. That's because the algorithm in the KLR doesn't use feedback control monitor boost levels. Therefore what happens is you'll get different boost levels in differwnt cars with the same set of chips.
You can't use the LBE and cycling-valve at the same time and have the cycling-valve manage boost. It works the other way around with the LBE setting taking precedence. That's because the cycling-valve is trying to set a lower boost pressure, thus will be cycling on & off, yet the LBE won't let anything through to the wastegate.
Since the spring-preload will be higher, you want to turn DOWN the LBE setting to get the same boost as before.
" Point being I would like to use the boost ehnacer to reduce turbo lag, the chip set to faciliate higher boost levels, and then the stock cyclic valve to regulate the boost at 15 psi...am I missing something here?"
The chips don't do anything with the boost other than get rid of the overboost-protection. Numerous people have tried to re-program the KLR to make the cycling-valve increase duty-cycle (and therefore boost) but to no avail. That's because the algorithm in the KLR doesn't use feedback control monitor boost levels. Therefore what happens is you'll get different boost levels in differwnt cars with the same set of chips.
You can't use the LBE and cycling-valve at the same time and have the cycling-valve manage boost. It works the other way around with the LBE setting taking precedence. That's because the cycling-valve is trying to set a lower boost pressure, thus will be cycling on & off, yet the LBE won't let anything through to the wastegate.
05-01-2002, 10:47 AM
#3
Racer
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Thanks for the relpy. I understand that you can't use the LBE and cyclic valve at the SAME time, but after the LBE opens up at the pre-set 10 psi the cyclic valve should be able regulate the boost above 10 psi, correct? So do I need to get a MBC to accurately regulate my boost to 15 psi? What is the construction of a MBC? Is it just an adjustable check valve like the LBE? If so it would make no sense to have both, correct? The MBC replaces the stock cyclic valve, does it not?
