knock at top end

[turboaddict2]

Was doing some testing today on the parkway. I always got on it on a 4th gear roll from like 65 mph. I have the alky at 7 and have it turn on early like 10-11 lbs. When I got on it there was always transitional knock(first orange light on knock gauge) and then it would go away and then 3 seconds later knock went up to the second or third orange light and thats when I knew it was real knock and let off immediately . I think I was running 19 or 20 lbs. in 4th gear. Scanmaster counts were 800 o2's and 2.6 degrees at 65-75 mph. EGT's were at 1481. I let off at 100 mph. How can I get rid of the top end knock? Should I just turn up the pump speed to max? I want to change one thing at a time.

Using a PTE alky chip that has 22(or 23) degrees of timing and 100% duty cycle at WOT. Fuel pressure is set at 42 line off. Any help is appreciated.

 

[Turbo__Tim]

Lots of load on the engine in fourth gear. Personally I wouldn't run anymore than 18, but that's me I'm bluck, bluck. *G*.

1480* is not really knock territory, nor is the .800 0-2 reading. I was thinking you might be drowning the plugs, and running rich, but the egt's would show 1675* or so...

Come to think of it shouldn't you still be in third at 100 mph?

If you turn tha alchy up, you may flood the plugs, but I would try that first, keeping an eys on the egt's and letting off before knock gets too bad.

Got a stock rear in the car?

 

[turboaddict2]

Yeah stock rear on the car.

Lets say I'm cruising in 4th gear on the highway and some dude wants to play. Is it safe to down shift manually to third from 65mph?

I'll try turning up the alky and see what happens. I'll post back

 

[Red Regal T]

BETTER TO DO ALL YOUR TESTING IN 3rd GEAR. NO PROBLEM MANUALLY MOVING TO THIRD GEAR AT 65mph. YOU CAN LOWER OR ELIMINATE YOUR TRANSITIONAL KNOCK BY PUSHING YOUR ALCHY TEST BUTTON AT THE SAME INSTANT YOU PUSH THE GAS PEDAL TO THE FLOOR.

 

[ALBERTAN]

I agree with running it in D instead of OD. Also, resist the urge to manually shift it up to OD while under load or you will see lotsa red lights on your knock gauge.

 

[turboaddict2]

Ok so it is safe to manually move to D while cruising at 65 mph in OD. I'll try that today. Yeah I always prime the lines right before I floor it.

 

[turboaddict2]

OK here's the update. I was cruising at 65 mph in 4th gear. So I slow down a little to maybe 60 and downshift manually to third. Then I went WOT and pressed the alky test button at the same time. Next thing I know I see the boost go to 20 lbs. pretty quick. Felt like a boost spike. Also I saw the knock gauge light up to the last red faster than the speed of light! . Let off immediately. I had the alky at dial 10 to be safe and had it turn on early. What should I try next?

Is it because there's too high of a load in 3rd gear too?

 

[turboaddict2]

Went out for another test run at night on the parkway. It was like 45 degrees. So I decided to try it again from 4th gear and hit 20 lbs. pretty quick with some transisitional knock but that went away. Kept my foot in it till about 105 then let off. Got good numbers this time. Scanmster read 816 o2's with 1.5 degrees of knock from 97-103mph. EGT's were 1501 and Alky was at dial 10. Only change I made this time was to up the fuel pressure to 46 line off. I think the car only needed more fuel

 

[Turbo__Tim]

turboaddict2 Great! I like it when people come back with a success story. You gave us all the facts, all the numbers. Good reply!

I see 1500 was the final egt number. At what point do you see knock? Maybe you don't know yet, that's ok. I was just wondering..

Too many times I research a problem in the archives, only to find the guy never posts back How in the heck are we supposed to learn without feedback?

 

[turboaddict2]

Thanks Turbo Tim! I think I saw knock coming in as soon as I let my foot off the gas just a little. THen I totally let off. GUess I'll leave the settings where they are.

 

[Razor]

Im with Tim on the low timing 92 chip in my car..actually ya shouldnt be racing on the street I usuall go down to 50 mph then drop it into second..yeehaw

Your stiill a bit rich at 800..could be the chip has to much timing.

Also I assume your running straight denatured with no water additive..

Hot motor will detonate more than a proprly cooled down one.

 

[turboaddict2]

THe PTE alky chip i'm using has 22*. Running straight denatured with some wd-40 lubricant. I told PTE to program the chip for 22 degrees because since I have an alky kit I thought that timing would be good for taking advantage of the systems cooling benefits.

 

[Steve Hill]

>>"Running straight denatured with some wd-40 lubricant"<<

There's the likely problem. Looks like you're too rich w/straight alcohol. Plus, not enough octane to work well by itsself.
Mix in water, say 40% to start, and keep the WD, or any lube, to a min., or better yet none if you don't have corrosion.

You have to learn to juggle your fueling along with the w-a. You're limitations will depend entirely upon flow, mixture, and atomization.

At 20lbs and 22 degress you've got lots of 'room to grow'.

 

[turboaddict2]

I'll try the 40% mix. How come other guys have good results with running straight denatured and some use water with denatured

 

[Steve Hill]

>>"How come other guys have good results "<<
there are variables, from car-to-car, which influence the process of detonation control. Straight alky does seem to work better with alum heads, perhaps because the alum conduction of heat is something of a substitue for the water. I have no direct experiece to report on this because I'm still exploring the limits of stock irons.
Straight alky can give a false sense of results because it tends to be very forgiving with the a/f. That does not, however, mean it is running properly. I.E., too rich is still too rich.
For the average turbo buick guy with iron heads, stock cam and the usual etc, a 50-50 mix should be very effective, and the added bonus of 'feedback' in that you will definately know when the fluid amount is too much (drowning out) or too little (knock).
Unlike sraight alky where you can just keep adding and the engine just gets lazy. Unless you have a w.b. you'll never know.
The water addition might seem to require more initial figuring out, but actually it comes down to just add timing and boost until knock, and/or juggle the fueling to get reasonable egts, then more w-a, more boost, etc, etc, until you reach your comfort level.
You will have it right when you can run to top rpm in fourth w/o knock. And if you're daring, do this with high boost and timing.
This might take a considerable amout of spray

 

[turboaddict2]

Thanks Steve! Thats good info. Just what I wanted to hear! I just added water to the denatured. Probably 40% water since the bottle was a little over half. I'll post back with results with the water mix

 

[Razor]

One more add on..you have to also adjust the amount of w-a that the motor can handle beyond the fuel pressure adjustments..at which time you also have to look at exactly how much denatured works best in the mix.

I dunno, the cars i've had experience with that run over 23lbs of boost have had the best results with straight denatured. Whereas the amount of denatured is "trimmed" in as well as fuel pressure to get the rite "0" knock performance using an EGT meter and O2 for reference. I usually run around the 1600-1625 mark through the traps.O2's in the 760-770 range.If I run 1500 then the O2's will be 800's..

The times I've tried running high boost with water mixed in in any amount have netted knock more than straight. I do understand and will agree that at the 22 lb level water can work with denatured. And at 22 lbs too much denatured will bring O2's up and bring down EGT's. Just as it would at 25..

But at the same time I have not tried increasing the flow of alcohol past where its at rite now.

Turning down the pump and running less straight denatured also has great results,but probably have better results turning up the pump and running a mix. It all depends what the car likes at the boost level you want to run.

Just my .02