alright well i hear people saying that you can run as much boost as you want as long as you dont knock. i have a tune for 20.5 on 91 octane. if i raised it to like 22 psi and it didnt knock, could i leave it there without any damage?
ok if thats so, how can i sense knock? my cars never knocked (i dont think) so im not sure what to expect...anything? thanks

 

It won't knock even if you are running 22psi on 91pisstane because your ECU is pulling lots of timing. As far as I know, you are not going faster with 22psi than 20psi if your ECU is pulling timing.
So NO! stay with 20psi or 19psi if you want to be safe.

 

Hold on there, partner.

The ECU pulls timing when it detects knock, so you were just a little confused there. Running too much boost for a given octane will cause knock, which then causes the ECU to pull timing, thus sapping power.

JSYEVO, you have to have a device to log knock or log timing. I use a pocketlogger, then do a 3rd gear pull and read the timing. If it goes flat instead of advancing or drops lower (worse), then I know I'm knocking.

Another way to see is if you get your car dyno'd, you will see the power dip wherever timing is being pulled. That's an indication that you're knocking, which is a result of too much boost or being too lean.

 

I recently had my car tuned on 91 and i made better and more power at 20 vs 22 psi (no meth)

 

If you have a stock ECU you will only get about 25psi and then your ECU will cut fuel and pop a SES light no matter what octane you are running. Have had it happen to me a couple times when the weather was cool and I hadn't adjusted my MBC.

 

I'm not sure how that's relevant to the question.

 

Good information. I too am using a pocketlogger to keep track of timing and knock..

 

off topic- but how much is the pocket logger and where can i get one? thanks and sorry for the hijack.

 

This is a searchable item, btw.

You can go to pocketlogger.com or piece one together by obtaining:

1) Palm M100 or M500 used off Ebay or Amazon, including hotsync cable

2) T16-003 Interface from Multiplex Engineering.

3) Free logging software. I use Palm'N'Stein from the TunerStein website, but if the website is down, you can get other software elsewhere.

 

ok so i am very computer illiterate i do have a PDA what else do i need to be able to do what you do with yours? what all do i need to order? i just dont want to wase money and order the wrong thing. thanks for the help warrtalon

 

I gave you the instructions above. Just skip step #1. The place where I got my software also gave detailed instructions on how to install it, then use it.

 

I would not listen to whomever told you this at all

As suggested, you need to see what the ecu is seeing to determine how much, if any, headroom you have.

That would involve a datalogger to look at timing in relation to TPS. From there, you'll be able to see if the ecu is taking out timing. If it is not, you are probably ok to increase boost, but just realize it may not make the car run any better

 

got it

 

when I had my car "street tuned" by Dynoflash with his equiptment/data logger.

Should we have turned up the boost untill I had some knock/pulled timing. Then turn it down untill it stops or goes away?
The first thing that was done was the AFR's then we turned up the boost to 24 PSI , no knock and very smooth pull till redline. Should I have tried to go higher? or get a better MBC because I did have some boost taper at redline.

Can you personally tell when your car is pulling some timing?

I don't mean to jack the thread but I think it along the same topic.

Stock turbo at 23/24 PSI

 

I'm not sure who you're addressing, since there's no quote.

If it's me, then I can tell you that I pull timing from 5500-7500 in 3rd and 4th if I try to run more than 21psi on pump gas. I only run 23-24psi on race gas. Sometimes, people's boost gauges read differentl, so it's hard to compare directly, but 23-24 is definitely too high on pump gas. I don't know how there would be no knock at that boost level on pump gas when tuned to a good AFR of 11.3-11.5 or so.

Your boost SHOULD taper...that's natural for the stock turbo. I don't even see 20psi by 7000rpm, and it drops as far as 18 by the rev limiter.