shiners780

What exactly does an aftermarket KLR chip do differently than a factory KLR chip? Can you use an aftermarket DME chip with a factory KLR chip? Thanks.

Van

Jim, my understanding is that the KLR chip sets your boost level.

I, in fact, use a non-stock DME chip with a stock KLR chip in SP3 - the DME chip controls the fuel mapping and redline.

shiners780

Thanks Van. If the cycling valve is deleted in favor of a MBC or LR boost enhancer, does the KLR chip selection matter?

This is not for my application, by the way.

sawood12

I thought KLR was purely there for knock detection/prevention and protection (i.e. translated from german KLR basically stands for 'knock computer'). I.e. when it detects knock it retards ignition timing first then switches the cycling valve to try to dump boost. So I was under the impression the KLR doesn't control boost at all - is boost not controlled/regulated by the wastegate?

So when bypassing the cycling valve and using an external boost controller with your wastegate (or a modified wastegate with a stiffer spring and/or shims to get higher boost) you need to change the coding in the KLR to prevent the overboost/knock protection functionality from working, hence the need for an aftermarket KLR?

Van

The manifold pressure sensor is located in the KLR. The KLR is also what operates the cycling valve - and the cycling valve is always open... the KLR closes it to build boost while you accelerate, and then as manifold boost pressure increases, the KLR lets the cycling valve go back to it's natural, open state.

Remember, the KLR is really called the K/CP unit - Knock & Charge Pressure.

cb951

Not sure about other chips, but for 951MAX chips (Russell Berry), a KLR chip is provided, but I believe the stock KLR chip can be used, even if the cycling valve is bypassed with an aftermarket boost controller (mbc or ebc).

If you have a MAX chip, check with Russell. My best guess is that the DME chip will disregard the info sent from the KLR unit, thereby providing no overboost protection. IIRC, it's actually the DME unit/chip which retards timing and cuts fuel based on an overboost condition as sensed by the KLR unit (in a stock configuration).

fast951

If you are not using the cycling vlave (no boost control via KLR), then the KLR will function as knock control, and will drive the factory boost gauge.

The DME determines overboost not the KLR. (actually overload should be used instead of overboost as the DME does not know actual boost).

To clarify before someone asks: When using V-FLEX, the DME does read actual boost as supplied by a MAP sensor.

sawood12

So does the KLR actually control and regulate boost then? i.e. is it effectively an EBC? i.e. is the wastegate diaphram only exposed to the boost pressure signal once the KLR detects that you are approaching or at max boost and it opens the cycling valve? If so then isn't it acting in the same way as an LR Boost Enhancer?

Van

No. The KLR works the other way. It (via the cycling valve) keeps the wastegate diaphragm open to the intake manifold all the time - except when it's trying to build boost - then it uses the cycling valve to stop allowing the boost pressure to go to the wastegate.

Watch this video:


The buzzer is wired up to the cycling valve (which, remember, the KLR controls). When you hear the buzz, the KLR is closing the wastegate. At all other times, the wastegate is connected to the intake manifold - pressure in the intake manifold = open wastegate. At the end of that video, my DME was going into overload protection because the volume of air being measured by the AFM didn't jive with the position of the throttle body - not because of an overboost problem (which I initially thought it was).

As you want boost to build, the buzzer buzzes a lot. As boost pressure rises, it buzzes less until it stops all together. At this point, the volume of exhaust gas is so much, most of it still gets to the turbo, even with the wastegate open.

This is a fail safe system. At full boost, the wastegate is always fully open. If your KLR dies, the engine shouldn't explode because of an overboost situation because the cycling valve is normally open.

Now, a Lindsey boost enhancer is a little spring loaded device that prevents boost pressure from going to the cycling valve, and thus the wastegate, until a certain pressure threshold is reached. This works in conjunction with the KLR closing the cycling valve to build boost even faster (since absolutely zero boost can go to the cycling valve until the spring is overcome by the pressure).

These cars (in stock configuration) reach maximum boost because: Porsche specially selected the components (wategate, spring, turbo size, exhaust geometry, etc.) to all work together. There is no electronic or manual boost control - but rather "situational boost control".

That's why shimming the wastegate raises the boost (and then the KLR chip has to be reprogrammed to NOT send an overboost signal to the DME). A more efficient turbo would also raise the boost levels.

TurboTommy

You're right, Van;
the stock boost is controlled by a combination of components.
But, the CV is one of those components and is like an EBC to control the boost. Its duty cycle opening an closing, rapidly, the pressure line going to the wastegate determines how much pressure is going to the wastegate.
The only aftermarket KLR chip, that I know of, that changes this duty cycle, is Autothority. But they don't change this duty cycle to increase boost; they change it to have the boost come on more linearly to the opening of the throttle.

Van

Sure, the cycling valve can be used and manipulated how fast the boost comes on (like a restrictor in the banjo bolt or the LBH), but it can't increase the max boost pressure. Max boost is achieved when the cycling valve is at its rest, or open, state. You can't get higher boost by having it "open more".

(But you could lower the boost by having the KLR not close the cycling valve to initially build up boost pressure. You can try this by connecting the the banjo bolt line directly to the wastegate - you can't get over about 1.2 or 1.3 bar absolute pressure. It's like a chemical reaction that needs a catalyst to start - the wastegate has to be closed a little to spool the turbo up to build boost, but once it's spooled up, it can sustain boost even with the wastegate open.)

TurboTommy

Van;
I don't think the CV can be described as fully open.
The cycling valve "cycles" back and forth very quickly, between open and close.The duty cycle of this device determines how much time it spends at "open" vs "close".
That being said, no one has used this to change max boost, but one would think it is possible.

Van

Ah, I gotcha. Have it not go back to the full open state (no buzz on my video) but have it continue to stay closed some for a higher boost level.

That wouldn't actually be changing the duty cycle, but rather changing the curve or duration of the "duty cycle pulses".

shiners780

See what I started?

Now y'all are giving me a headache.