Wow.........what chips are you currently running with that boost and fuel grade????

PS: Knock sounds more like small metal ***** rattling around in a can, you can imagin the sound

 

The reason your intercooler pipes are SO hot is because the turbo is heating up the air THAT much, which is VERY bad. To play it safe, I would turn the boost down to 15psi or even a little less. When you get the money and put in chips, fuel bar reg., etc, put your car on a dyno or put in a wide band O2 sensor to see exactly where you stand in air/fuel ratio. From there you can up your boost some to get the best performance out of the car, but even with that said, don't run over 18psi because you don't get any more HP in a car because the intake charge temp is SO high.

 

Wait, I just thought of something... What does the guage read with the engine off and the ignition on? Does it read 0, or does it read ~14 PSI? If your guage is reading absolute pressure like the one in the instrument cluster then there's nothing weird going on here. The engine knocked, the KLR went into overboost, and it limited the engine to 1.2 BAR absolute pressure. If that's 22-24 PSI absolute pressure, that's only 8-10 PSI above atmospheric, which is about right.

 

Good thinking ZV, but it is a relative pressure gauge (i.e. it is zero when the car is off). I should have mentioned that.

Porsche-O-Phile, what I meant was that the excess unburned gas was probably causing my catalytic converter to roast itself. That and the fact that it was probably still burning when it entered the cat didn't help either. I didn't mean to say that all the excess gas was heating my intake air.

I wish I could dial the boost down, but I don't exactly have a way to do that. I have a restrictor banjo bolt on the intercooler pipe, and stock boost control other than that (Except a shimmed wastegate).

There is something I don't get. Everybody talks about bad things happening if you have 15psi chips and run 18psi, or 18psi chips and run 23, etc. Why?
Don't the chips read the amount of air coming in, and meter fuel accordingly?
Or is the worry the ignition advance? I just don't quite get why it is such a problem.

If I were to get a set of agressive 18psi chips, and run them at 15psi on the street, would bad things happen?

I'm thinking more about the noise, and I am almost 100% certain it was knock. It sounded like a dulled version of metal ***** rattling in a tin can, much quieter too. Like I said, I heard it, but my dad who was in the car with me did not. I previously thought knock was always a pretty loud thing. Also, the car did kind of buck a little when it made the sound.

I think that's the last time I get my right foot into it until I at least put some 91 octane gas in there. This was a real eye-opener.

 

There are numerous reasons why what you were doing is so bad.

Two important ones are:

You are probably running lean, as the DME's enrichment table is based on throttle position and not boost. It does not expect that full throttle is flowing as much air as you are flowing, so it does not inject enough fuel. The intial bpw calculation involving airflow/rpm may save you a little because the increase in airflow will be picked up, but the enrichment table for full throttle still wont be enough. Running lean will burn headgaskets from hot combustion, heat up the combustion chamber, and lead to knock.

Second, the turbo is heating up the air so much at 23 psi (if you can really even make that) that you are not gaining power. Look up compressor map on google, and then search rennlist for the k26 one. You will see that it is way out of its efficincey range. Hot air is not what you want, you are overloading the intercooler, and once again leading to knock. Eventually you will kill the turbo due to excessive heat and compressor speed.

I think it would make this thread very interesting if you pulled your spark plugs and took pictures of them. I for one am very curious.

 

Yes, do that. If it is bucking and pinging - you are seconds away from headgasket failure - no bull****.

 

When you have chips that are made of 15psi with a stock AFM, you MUST run 15psi to get the correct air/fuel ratio. You can go up maybe 1psi and be OK, but if you turn it down from 15psi you will run rich which is safer then lean. When you get the MAF or MAP, it measure the air going into the engine, so it corrects the air/fuel ratio as you change boost. That is if everything working right in that system as well.
What happens in a stock car (AFM) but with chips, when you put your foot down to go it uses the O2 sensor up to a certain point to get a good air/fuel for gas milage. When you foot gets farther down to take off fast, the O2 sensor is not even looked at. This is when the chips kick in. The chips will tell the other sensors what is the best fuel to add for certain load and RPM but it has NO WAY of knowing if you are pushing more or less boost. That is why it is SO bad to run higher boost then the chips are made for.

 

" has NO WAY of knowing if you are pushing more or less boost. "

This is wrong. The base pulse width for fuel injection is calculated from airflow, then modified based on the tables in the chips. It does realize he is flowing more air, but the wot enrichment table will be off. Only, he will not be running as lean as you think he is.

 

O, I thought that the chips would just take over assuming that the car was pushing 15psi or whatever boost, then add the correct fuel to give the best air/fuel ratio.

 

See if the chips assumed I was at say 15psi, they would run insanely rich until the turbo spooled up.

I forgot about the enrichment tables. I don't entirely understand why they are necessary though. Why can't it just watch air flow, and advance ignition based on maps?

I forgot about forcing the turbo to over-rev. I'd bet that's not so good for it.... I can't afford to be replacing turbos as well, so turning the boost down is definately in order. I don't really understand what compressor maps are, or how to read them, so I'll be doing some research tonight.

mark944turbo, I assure you that it did indeed make 23psi, and it was very fast at 23psi

All of this said, it might be a good idea to return to some stock chips while I get everything in order to make some extra power... Perhaps somebody is looking to get rid of some stock chips and a stock banjo bolt?

 

My understanding is that the AFM is maxed out above a certain RPM (around 3500ishk @ WOT)...so the DME/KLR only look at throttle position because that is all they have. If you search the archives you should find more information on this.

You can't run 87 octane and run 15psi of 18psi or 23psi... you need to stay out of the boost until you can afford the best grade of gasoline commonly available.

You spent a lot of money on your engine rebuild, dont throw it all away running 23psi and 87 octane.

87 octane and 15psi is even silly.

No I dont know exactly at what boost level you will knock with 87 octane, but I do know that it is silly to try on an engine that you just invested many thousands of dollars into. Knock can blow your engine to bits. The KLR can only retard timing so much. If you have the cycling valve bypassed, then the KLR can do nothing to limit boost.

My recommendation is to stay out of the boost until you get everything in order. IMHO that should be stock chips, stock boost control until you can afford to do it right. Using the stock chips and stock boost control you can theoretically run 87 (because the KLR will be able to save the engine before things get too bad), but I think it would be wise to run the minimum octane fuel that Porsche recommends.

 

First off if you are running through the CV it's not possible to boost to 23-psi, the k26/6 won't hold boost to 23-psi. Max boost for stock set up 13 or12-psi, at red line goes down to, 8 or 9-psi. Stock WG won't even hold that amount of boost. It's been said here before get a boost gauge!

 

I ran 20+psi for only a second or so before with a fuly stock car, the CV had a broken nipple. It got ,my heart pounding hard for a moment since i knew that there was something wrong. Eventually, it was the CV and i was lucky that nothing went wrong.


Thing is, even though the CV had a broken nipple, it wasn't easy to detect since the broken piece was stuck inside the hose from the wastegate.

 

pk951 do you honestly think I would say it makes 23psi of boost if I DIDN'T have a boost gauge? It makes 23psi. Period. It is the stock K26/6, unless somebody swapped out the guts, which really wouldn't get them too far, since the housing sizes would still be the same. It uses the stock intake and exhaust plumbing, so it is a stock-sized turbo, most probably with stock internals.
Second of all, I have no idea what has been messed with down under the intake. I reconnected it exactly as it was, with new hoses to replace all of the cracked ones. I do not know if it runs through the CV or whatever, but I have yet to discover another method of boost control installed on my car. I know a lot of people drill out the CV to attempt to increase the maximum boost the KLR allows, I do not know how this works, but I understand it is often done in combination with shimming the wastegate (which was done on my car), as well as installing some of the older aftermarket chips and a banjo bolt.
Hence why I would like to install an EBC, so I at least know what my method of boost control is, and know what it is set at. It obviously doesn't hold 23psi to redline, it tapers off to 7-8psi by then, but it holds 20psi past 4000RPM. It will peak at 22-23psi in the 3000's, which happened to be where I got knock.

Anyhoo, status update. Filled 'er up with 94 octane this morning after pretty much running it dry. Decided to get on it hard on a highway to see if things had changed. It's much cooler out today than it was when I got knock, but it ran up to 21psi with no knock at all, did a 2500RPM - 5500RPM run in 3rd gear to check it out. Everything was nicely warmed up, and I had just been sitting in traffic for a while, so I suppose everything was as heat-soaked as it could get in this weather. I do believe this is good news.

Adrial, I think there is one thing you're forgetting to consider.
You mention that you can't run 15psi on 87 octane. Technically you can, you just can't run as agressive ignition timing as you can on 91 or 94 octane. This is why the stock chips are fine on 87 octane. They run 11psi with relatively conservative ignition timing. That said, if I got really agressive chips designed for 18psi, I would probably have to knock it back to about 10-11psi before I could run 87 octane. Which if I understand you correctly is what you were arguing, and it is entirely correct. So I need to find some middle ground between ignition advance and boost that will allow me to have some fun on 87 octane, but lots of fun on 91
I forget how this goes, but there is some rule of thumb that follows like this: For every 1 octane point you increase your fuel by, you can add 2psi of boost or 1* of ignition timing. I don't think those numbers are right, does somebody know what it really is?

 

All this talk about octane has got me thinking.....

Do those octane boost additives work???

Do you guys use fuel additives???? and what do you reccomend???