Steve Cooper

Danno, any thoughts on whether I should leave the cycling valve in place or whether I can delete it and route the wastegate directly into the Boost Enahncer? If one were to bypass the cycling valve, should the electrical connection to it be attached as normal?

Thanks,

Steve

Danno

Steve, you can leave the CV in place or bypass it. Either way should work. However, the stock plumbing can develop cracks and leaks and cause boost-spiking problems. In which case, you can run a line directly from the boost-controller's outlet straight to the wastegate.

You can leave the CV hooked up electronicly or not, it doesn't matter.

Steve Cooper

Thanks Danno. I buttoned up the intake earlier this afternoon and left the CV intact. It sounds like there isn't a difference between the two set-ups.

adrial

With the CV in place and a jet in the banjo bolt (autothority style) compared to no CV and just a boost controller, I noticed a huge difference.

Primarily was that now I make boost at part throttle. This really helped scoot the car along when I dont wanna REALLY go but I wanna move decently.

In terms of lag, I didnt notice much of a difference, boost still hit at the same 3600ish-3700ish rpm ....

alpenweissisnice

Just so I understand, Adrial, the setup that gave you the best performance was no CV and the boost contoller? Are you using the Guru chips?

adrial

Yup, no CV and boost controller.

With the CV in place and a true boost controller (as opposed to a restriction in the banjo bolt...which just restricts flow to the CV and thus the wastegate) you may get a good amount of boost at part throttle....that I'm not sure of. What I am sure of is that no CV and boost controller is far superior to a jet in the banjo bolt (with the CV still in place).

I was using autothority chips with the banjo bolt and now steve R chips with the MBC.

Looking to move to Guru stage 2 or the standalone engine managment that danno just spilled the beans on (price to be announced still).

alpenweissisnice

Thanks Adrial...I had an email dialogue with the guys at BoostSciences...They said that you could plumb the Reliaboost either way, with or without the CV, but the boost would come on harder/faster with OUT the CV. I am considering some mods (other than what little I have already done) and am strongly considering the Guru deal with 3 bar FPR, Reliaboost, wastegate shims, and chips. On the other hand, I almost hate to modify a car with only 50K miles on it...I have plenty of fun in near-stock trim...

Jake951

My understanding of the CV is that in factory stock form, the engine management computer varies the duty cycle of the CV to exercise a degree of control of the boost. Among other things, TPS input can be used by the computer to develop an amount of boost that is more or less linearly proportional to throttle position for "better" driveability. If the CV is removed, then the computer loses this degree of control on the boost and I would expect the boost to be more sensitive to throttle opening. I think this is what one of the posts above was saying. Correct me if I'm wrong here.

I'm not sure if boost lag is actually reduced or not, but I suppose it could be if some lag were programmed in by the factory for driveability reasons.

I'm using the GURU MAP-1 setup and I'm not sure how the GURU chips control the CV relative to the factory chips...comments, Danno? Actually I'm about to do the CV bypass experiment, so I'll get a personal data point on what happens.

Danno

Hi Jake951, the CV is completely bypassed whenever you install and aftermarket boost-controller. These sit inline with the CV and restrict pressure going to it. That's how they raise your boost-level. So even as the stock KLR is trying to cycle the CV on & off to send pressure to the wastegate to set boost at stock 11-12psi levels, there's no pressure getting to it, the boost-controller has shut off all flow. Then the aftermarket controller will only open when the desired boost level has been reached, in this case 15psi.

Many people have tried to use a chips-only approach to managing the CV and boost (like Cyntex), but to no avail. This is partly due to the read-protect bit being turned on in the KLR's ROM, which prevents anyone from reverse-engineering the programming.

Also problematic is the open-loop operation of the CV's control. The KLR just spits out a fixed duty-cycle curve without care as to what the actual boost is. It doesn't sense the boost and re-adjust it's duty-cycle to obtain the target boost. This means that the same KLR programming will yield different boost-levels on different cars depending upon the strength of the wastegate spring. If you've got a strong spring, you may see 13psi, but another with a weak spring can only get 10psi.

However, there is a caveat when using an aftermarket controller in-line with the stock CV. And that's if you have cracked hoses or ports on the CV or if the CV has failed in an open position. This will leak out pressure that's being sent by the boost-controller to open the wastegate. Since this pressure is leaked out along the way, you'll end up with more boost than the boost-controller was set for, thus you'll get overboost or boost-spikes. In cases like this, you want to run a new line directly from the boost-controller's outlet straight to the wastegate. This will completely bypass the stock lines and CV to remove them and the problems they may be causing.

Jake951

[quote]Originally posted by Danno:
<strong>Many people have tried to use a chips-only approach to managing the CV and boost (like Cyntex), but to no avail. </strong><hr></blockquote>


Thanks for the (as usual) informative reply, Danno. I don't know if you can give away any trade secrets here but do the GURU chips or the other aftermarket chips just completely abandon control of the CV and run it 100% duty cycle? Also, won't the factory chips have the same problem of inaccurate control of absolute boost as aftermarket chips for the same reasons (weak wastegate springs, etc.)?

blu951

I have bypassed the CV and have an LBE direct to wastegate. Boost builds faster I feel by butt dyno...

Danno

Whoops, I didn't get around to answering this before the holiday break...

" I don't know if you can give away any trade secrets here but do the GURU chips or the other aftermarket chips just completely abandon control of the CV and run it 100% duty cycle? Also, won't the factory chips have the same problem of inaccurate control of absolute boost as aftermarket chips for the same reasons (weak wastegate springs, etc.)?"

Ok, there is no aftermarket chip that can accurately manage and increase boost over stock by controlling the CV alone; they all forget about controlling the CV and just removes the overboost-protection trigger to the DME (including ours).

The problem is there is lack of close-loop feedback in the KLR's management of boost. It just dumps out a fixed duty-cycle curve to the cycling valve regardless of actual boost conditions. By trying to reprogramming the duty-cycle curve on the maps, you can increase the boost... but... depending upon the condition of the wastegate spring, you'll get varying degrees of boost with different cars. On a car with a new stock wastegate with strong spring, you may see 15psi of bost. Plug that same chip into another car with a worn-out spring and you may only get 9psi. Again, it's due to lack of closed-loop feedback control in the KLR's design which doesn't check and doesn't care what actual boost is. Numerous people have tried to reprogram the boost curve using a chip-only upgrade waaayyyy back in the'80s, failed and had given up.

That brings up what to do when installing an aftermarket boost-controller like the LBE or our Reliaboost-1 unit. I've directed people who are <a href="http://forums.gururacing.net/viewtopic.php?t=9" target="_blank">installing the controller</a> to place it in between the banjo-bolt and the stock hard pipe under the intake manifold leading to the stock CV.

By retaining the stock CV, you are providing a drain between the controller and the wastegate to dump trapped pressure after the controller has closed when the desired boost-level has been achieved. This causes the wastegate to close quickly as well and leads to a faster feedback cycle and gives quicker and flatter management of boost....

HOWEVER, if you have old hard cracked rubber lines under the intake manifold. Or if you have a busted CV, or any cracks in it, then you will be bleeding off the pressure signal sent by the boost-controller to open the wastegate. This leak will cause a delay in opening the wastegate and your boost will overshoot the target pressure before the wastegate opens. This boost-spike is not really desireable.

So in this case, yes, hook up a thick new hose (no thin, flexible silicon hoses allowed, 1/8" wall-thickness minimum), directly between the boost-controller's outlet and the control port of the wastegate. This will then give the most direct and quickest wastegate activation possible, so it'll open exactly when the desired boost has been hit. A built-in drain hole on our <a href="http://www.boostsciences.com" target="_blank">Reliaboost-1 controller</a> also drains trapped pressure as well, allowing faster cycling and tighter boost-regulation than the LBE.

slevy951

So, Danno, how does the Reliaboost compare to a MBC(****, wheel of fortune, whatever you want to call it)? It's my understanding the MBC's won't drain trapped pressure and cause boost spikes. Do I have this correct? Is there any way to modify the MBC to drain the pressure off?

TIA.....