JoeN951

This is something I have been thinking about and have not found the answer.
The Bosch KLR in our cars is the stock way of electronically controlling the flow to the turbo by opening and closing the wastegate. Correct?

So here's my question. If the factory can use the KLR to control boost pressure, why can aftermarket chips not use the KLR to hold boost at higher RPM's? Then we would not have to install aftermarket controllers, electronic or manual.

Someone that knows please explain this to me. Thanks.

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87 Alpine White, under reconstruction

Evan70

They can. The problem isn't with aftermarket chips, it's with the stock cycling valve that actually controls the wastegate. The stock setup starts bleeding off boost way before whatever your limit in the chips is. An aftermarket boost controller (Lindsey boost enhancer, Accuboost, Reliaboost, MBC, EBC, etc) will hold the wastegate completely closed until whatever you have the boost controller set to. Even with a completely stock car and chips, you can see a benefit from an aftermarket boost controller.

JoeN951

So what we need is really a better quality cycling valve? Just seems like this would be a lot easier than bypassing it and having to install a controller.

Evan70

I don't really know enough about the cycling valve itself to say for sure that is the main problem. It could be a combination of the way the computer and cycling valve interract, or just how the KLR tells the cycling valve to act. The easiest solution is to get something like a Lindsey Boost Enhancer that blocks pressure being sent to the wastegate until whatever you dial it in for. You can even use the LBE with stock chips and cycling valve if you want.

reno808

What you have to do is ERASE the CV and install an EBC what a BIG DIFFFFFFFFFFF

JoeN951

Reno that was not my question...looking for a technical answer as to why the factory klr cannot do this with a chip programmed as such. KLR is no longer being used so what component is measuring how much boost is actually being produced....how does the DME know and adjust fuel flow or does it ever?

TheRealLefty

Interesting question and theory. As i understand it, the KLR receives info from the cycling valve that feeds knock sensing data to the DME designed to retard timing as part of the boost control/overboost protection/fuel pressure loop. With the sincere request to stop me it I screw up (information is power!), I assume the "full boat" mod of EBC and chip serves the same function and controls the same parameters.

Soooo, your question IS quite interesting. Would an improved cycling valve improve the performance of an otherwise stock 951? To a point it sounds like it could. Seems to me, where that mod would fall of the table, would be when intake hardware/waste gate upgrades would result in fuel pressures and boost pressures outside of the stock chip's map.

At that point OE chips would be screwing up by running too lean and trying to kill fuel when sustained boost exceeded it's map.

UK952

The cycling valve sends an 'open' signal to the wastegate, a boost enhancer, reliaboost etc. can delay this signal. The pressure in the exhaust will force open the wastegate and there is nothing the CV can do to opose this. This means if you have a weak wastegate spring the wastegate will open whatever the CV does. The CV is also a source of leaks.

With a dual port wastegate and an electronic controller you can hold the wastegate closed until you want it to open (max boost). The pressure in the exhaust wont force it open early so you build max boost quicker.

The CV was designed over 20 years ago, electronics have got more reliable and cheaper over that time, A DPW with EBC is the best solution now.

I guess the ultimate solution would be an engine managment system that could control A DPW and also spot detonation/overboost and do something about it. Asking the poor 20yo ECU to cope with this might be too much.

Tony

TheRealLefty

Great post, Tony. Good analysis of the benefits of the ubiquitous dual port waste gate/boost control mod vs. stock waste gate/cycling valve/boost enhancer option.

UK952

Thankyou

gt37vgt

well i run a boostinahncer thing (inline pressur relif) and just shiimed the hell out of the gate like 10mm so th inline thing is benck testded at say 14 psi so the boost romps on strong until then the klr controls the boost happily i've just stuck 8 psi in the top of it it makes 22psi on good fuel and 17 on bad fuel . Ive found with the incresed gate pressur and klr isolated under 14 psi its fine .
dual port puts pressur in to keep the gate closed . i think maybe the klr CV duty cycle is maybe only two or three settings also seems no thought about it until this inline relif valve was already everywere

Rogue_Ant

The KLR can only read up to ~15psi of boost. IIRC


Rogue

Geneqco

So we know the KLR controls the cycling valve which in turn can use air pressure to open the wastegate. Under what circumstances does the KLR have the cycling valve open the wastegate:

Overboost conditions?

Knock conditions?

Or both?

Anything else? (I think if the KLR is not operating, the cycling valve will be in the position that opens the wastegate.)

RKD in OKC

The difference between the stock setup and an EBC is not really the CV. The CV serves the same purpose as the Solenoid in an EBC setup.

The advantages of Stock is that it will back off boost when sensing knocks. It does not get or use any signal from the CV but senses boost from the line that goes from the intake manifold to the chip where the boost sensor is mounted.

The disadvantage is that the stock setup starts opening the wastegate as soon as the turbo starts developing any boost at all. I remember LR measuring it opening with as little as 4 psi.

The advantage of an EBC over Stock is that you can easily adjust boost settings and not just one. And that you can set the gate pressure, or the pressure that the solenoid valve begins to open the wastegate.

And yes you can increase the max boost in the factory chips. This is done in several aftermarket chips to increase the power output. However it requires reburning the chips or replacing the chips any time that you wish to change boost.

theedge

It doesnt pull boost immediatly on knock, only if pulling timing and such doesnt work first from what I can remember. I think it was Danno who posted a little chart showing what it did but I cant seem to find it.