facboy

my original head gasket has been at 18psi now for about 10 months. knock on wood . btw jeff turbo voodoo doctor, that sounds kinda whacky to me. the stock CV is used for controlling boost isn't it? how are you going to stop it from interfering with your EBC? won't they both be duking it out and confusing each other?

i also don't see how having the CV there is an improvement over the EBC alone. the EBC will be newer and more reliable than the old worn out CV won't it? and it will regulate boost in the same way i would have thought.

Porsche-O-Phile

Not with judicious use and placement of check valves and chip / EBC balancing. This is an experimental setup but I don't see why it wouldn't work. The idea is to set the chips at a slightly lesser setting than the EBC. For example, if I ran a 15psi chip in the DME/KLR, I could set the EBC to maybe 14.5 psi. This way the wastegate will never receive an "open instruction" signal from the CV that is contrary to the EBC's. If anything, the EBC will be MORE sensitive / conservative to lean conditions and be able to send the appropriate "open a little bit" signal to the W/G. In an extreme situation where something fails or a problem occurs and detonation starts to occur, the CV would still be able to send a signal, pop the W/G open and save your head gasket and/or engine.

Again, this is a theoretical setup I'm mulling over and I'm going to be saving up for an EBC anyhow. Once I get it and set up everything I'll keep you posted on the outcome, but I really don't see the problem with it. Of course, some EBCs may incorporate knock protection (I haven't come across one yet though) and in that case, such a device WOULD eliminate the need for the CV entirely. I just think running very high boost with only an MBC is a time bomb and the number of milkshakes out there tends to substantiate this. . . An MBC simply can't make the precise adjustments necessary to prevent lean conditions at various points unless you're VERY lucky and VERY well-tuned (and the car stays that way). For one, I'd feel a whole lot better if the overboost / knock protection remained in some form rather than worrying about the possibility of a blown h/g every time you feel like tuning.

Anyone know if something like this has been done before? I'm not aware of it.

facboy

i thought the overboost protection was the only thing that triggered the CV. i thought the knock sensor only retarded the timing, but i'm not sure.

Duke

Besides what has been said already, a 15+ year old headgasket will go sooner or later. Often sooner.. So if you put in new chips, raise the boost and add 50 hp to an old, stock engine its not strange if the headgasket blow, even with good chips.

Mercedesben

How many hours should a shop charge to do a HG?

hosrom_951

Hehehe come here and my specialist would do it in ~2 hours or so

Bengt Sweden

When knocking occurs the KLR first retard timing and then, if that doesn't help, reduce boost in small steps. It doesn't smack the WG open. If that is needed as an emergency measure the fuel is cut off. Therefore parallel boost control unfortunately wont work, since the EBC will compensate for the KLR trying to drop boost. Fortunately with separate boost control you still have the timing retard and with the correct AFR you are likely to be on the safe side. For serious boost, you will need bigger injectors to go with your custom chips.
bengt

Porsche-O-Phile

A very good point also; IIRC the stock injectors are good only to about 260-ish h.p. Above that WILL require new injectors (and likely a 3-bar FPR) and probably custom chips to compensate for the higher flow rates of the larger injectors. This is where Guru comes in. . .

That won't be for a while though - I'm unlikely to push the car much harder than 15psi until I have a pile of new stuff to do all at once - the larger injectors, the EBC, a larger turbo (probably a Garrett of some sort), etc.