How much knock is ok????

[84wh1]

Just want to know, how much knock is ok?

I floored it yesterday and I got 7.1 degrees of knock! That seemed very high to me, so I instantly let off the gas.

Also, I tried to nail it again after that, and the car started to sort of let off or bog very lightly, Could that have been the computer letting off because I was detonating when I last floored it.?

BTW, I had a TRASHER 100 chip in the car and I was using a 114(2gal)/92 oct(3gal). mix.

Thanks

 

[Dean]

0.0KR is my goal, and whenever I see KR, I back off the setup to get 0.0. Some live with a couple degrees at any point, giving up a couple degrees more on the shifts. I may learn to live with that some day, but not yet.

7.1 is definitely high, if it is real, though with the octane you have and the relatively low boost, maybe not? What were the O2s

Your 114/92 mix... are you sure? Did you actually make this mix and then add it to your tank, in which case what was in the tank prior?

The computer doesn't "memorize" your last KR. Poke around and make sure everything is still hooked up nice and snug.

 

[Turbojorge]

Per GNTTYPE guides, it's "O.K." for anything less than 6* at any point.

I tune for less than 4 degress. When I do get knock, it's mainly transitional knock. Even then, I don't like to see it past 4* on the SM. With the street tune that I have now, I run 17.5 psi on a 20* timing chip and I get about 2.5* at 90mph and then it goes away till I let off. Thats when the car is cooled off and I go WOT just to see how things are. When the car is hot, I loose abot 1.5 psi of boost and then I get 2-3* at different times throughout the run. (It's amazing what heat does to these motors)

I'm still in the learning process myself, but I would advice to tune for less than 4*

When you say your car "boggs" that is the timing being retarded by the computer. When your not running proper octane for the boost your running, the computer calls back the timing and It throws fuel. YOUR DETENATING THE MOTOR AND YOUR PROLLY RETARDING THE TIMING MORE THAN 6*. Turn down the boost or run higher octane. (Or Xylene like I do ;<)

HTH

 

[84wh1]

I'm not sure what the o2 were, i just got the scantool and dont really know how to read everything right yet. I'll check it out later today, BTW, the other day(friday) I hammered it in first and got 14 deg of knock!!! I also heard a POP, so I let off right away.

About the gas, i dumped in about 2gal of 114 and then dumped in about 2.5gal of 92.

 

[Turbojorge]

The numbers to the left of the knock count on your scanmaster are the 02's. You don't have to hit any buttons to get to that screen once you turn your car on. If that number is bellow 750, than you are to lean at WOT. See if turning up the fuel pressure helps the numbers get between 750-780. Then, check for knock. If you still get knock, then you are too high on boost. Turn the boost down and try it again.

BTW, how much boost are you running?

Popping, weather out the intake or exhaust, is not a good thing. You don't want to get your headgaskets mad at you so turn down the boost.

 

[84wh1]

Well, I drove my car agin today, and I checked my O2s. They were at about 775-825. Boost was only at about 15 pounds, but thats with the wastgate all the way down. And I was also getting about 5.9 degrees of knock.

How can I get knock with 100 oct(est) in the tank and only 15 pounds of boost. Fuel pressure was at about 39 pounds.

Also, how come i only got 15 pounds of boost?

 

[Turbojorge]

Well, if your running 100 oct. and your only boosting 15 psi, then I think you may just be getting some False knock. Your 02 seem to be somewhat O.K. (somewhat meaning 775 is good and 825 is a little rich) but as long as your not leanning out too much(<750) you should be O.K. If the 775 is at the top of 3rd (say from 90-110mph @WOT) then your O.K.

You can adjust the boost by the wastegate. You cannot increase boost by just adding octanne. You need to disconect the rod at the bottom of the exhaust housing and give it 2-3 turns TOWARDS the turbo, then hook it back up. That should have you at 17-18 psi which is about as high as I would suggest to go with 100 octane. I would definetly adjust the Fuel pressure to 45 psi line off and work my way down until your 02's are within the 750-780 zone.

Is the car still poping?

 

[84wh1]

I had 5.6deg of knock, and the car DID NOT pop. I didnt take the car up to 110mph though, it was only as high as 100kph (60mph), then I had to let off, because I was already over the limit.

About the wastgate, the rod was as short as it will go, I cant increase the boost anymore. I have a slightly cracked header, so I might be loosing boost through there.

Thanks for the advise

 

[Turbojorge]

You can cut the rod and make it even shorter you know. Thats not a big deal.

Staying under the speed limit is always the safest thing to do, but you won't be able to fully tune the car correctly unless you see how it runs on the top of 3rd. Take it to a nearby 1/4 mile track and have some fun. Be sure to use good fuel.

Good luck.

 

[84wh1]

The thing with the wastegate though, is that where the rod connects to the turbo (that little rectangle piece where the rod connects to) wont reach out any further, if I move the rod down even one half turn, its too short to connect.

BTW, i'll probably have to go to the highway to nail it, since the nearest track to winnipeg is over an hour away!

Thanks for the help though.

 

[Turbojorge]

You can pull the rod out to make it reach. Just grab the rod tight underneath the Turbo and pull it towards you until you can hook the hole back on the pin on the exhaust housing. You won't damage anything by doing this.

I know how it is. The nearest track for me is 110 miles aways. It's about 1 hour and 1/2 drive at 70 MPH. Last friday, I made the drive. When I got their, it started rainning and they called it a rain out. I was pissed! I had already changed the pump gas for C-16 and I had wasted a gallon tuning. Good thing that I didn't mount the slick that I had in the trunk.

Good Luck.

 

[turbopete]

tuning

with my limited experience, i have found the following to be a good starting point.
o2 780-810 is a bit rich, but safe.
as for the wastegate rod, initially set it so half of the hole is visible. this should require you to moderately pull the rod to fit on the turbo.
i run 18 psi in first, 15 in the other gears every day with a 60k mile gn and good 93 octane.
i have not had any problems.

 

[Alan]

Hot air Car...?

 

[84wh1]

Yes, it is a hotair car. I think that some of the knock I'm getting might be false knock, because the yesterday, I stomped on it at about 20mph (with 94 oct in the tank) and the scanmaster read 19.2 degrees of knock . I think that seems almost too high to be possible without my motor blowing up at that second. I also did not hear anything but tires and turbo when it read 19.2deg.

Is it possible that bad spark plugs could cause detonation?

 

[Fred 86 GN]

Hopefully the 39psi fuel pressure you stated is with the vacuum line ON. With it off, all Thrasher chips (that I have heard about) want 45psi.

KR at 20mph and when stomping the gas on the street is fairly common. I have the same thing happen to my GN. I *think* it is wheel-spin induced KR. I just don't stomp it on the street anymore where it can downshift to first. It just goes sideways and causes lots of scary KR sometimes.

The 100 octane chip needs at least 100 octane to support it. I know it is painful to drive around on straight $4 to $8 per gallon race gas, but it is the only way IMO to be sure not to hurt the headgaskets...or using alcohol injection.

HTH.