No knock+1 turn = 9° !??!

[Weazel]

Hello all. I'm still monkeying with my newly installed SMC kit, and am trying to settle on a nice comfortable boost level for my mostly stock setup. Just the other day (80° ambient or so) I had 4 or 5 "digs" recorded on DirectScan. No knock whatsoever at a steady 20 lbs of boost. Alky on at about 13 psi (can't tell for sure) and pump speed at about 5.5. The car felt great...and no visible problems. So of course that means I'm not running her hard enough, right?
Anyway, so I take the wastegate rod in another 1.5 turns (shooting for 21.5 psi or so). Tested her again heading up a bridge on-ramp. I got 4° of knock or so through the end of 2nd and all of 3rd gear (only took her to 70 or so...in a 35 zone). I thought maybe the hill did something, so I would try again.
Same boost setting (21+ pretty steady, up to 23 or so on the shifts), but the air had gotten a little cooler (70° or a little less). Nice straight shot in the north end of town. I ran her from a dig up to 90 or so. I had HUGE amounts of knock, up to 9° in 3rd gear, and several degrees in the lower gears (which I almost never get).
So, my question is, WTF happened? Is that a typical jump for just 1-1.5 psi of boost? I thought the idea of sneaking up was to avoid any big knock numbers. 9° scared me. Could the cooler air have done anything? Did my kit just not fire on that run? (didn't see the light, I was busy watching the road). While tuning I am running a 10-15% mix of Xylene with my normal 93. So about 96 octane, just for insurance (which it looks like I needed here).
Help! Just trying to figure out the score. After the rain today I'll put in another gal of Xylene and try it out. Thanks a LOT!!!

 

[b231v6]

One thing that you'll need to remember is tuning for the street on alky is ever changing. Drive in the in the city on let's say an average day. Later that night you go to a friends house in the country. Foggy valleys crisp, cool,and clear the higher you get. The amout of knock will change with the conditions. Sometimes alot sometimes a little. One thing I've learned with alky is get a boost controller. When your car is tuned for the most possible boost with a few degrees of knock on the top end,set your wastegate. Then with varing weather or grade of gas,or whatever you can turn the contoller down in the to dial it in.
Without a contoller you'll just have to settle for lower boost numbers for piece of mind and just keep adjusting the wastegate.
Example my wastegate is set for 25 lbs. of boost. When its running great i'm full boost,and when it's not I turn it down to a minimun of 19. And of course you can also fool with the alky controls. I don't though.

 

[Red Regal T]

I never had a problem like that with my $150 diy kit. I guess I just don't have all those settings to mess with. Only changes I make are from hot weather to cold weather. Actually, sounds like it's not shooting enough juice. Must be your kit.

 

[turbo buicks]

try running more pump speed and turning the alky on sooner to get it in and working before temps rise. 5.5 is half pump speed and to runn more boost you need the alky. fact of life. i tried skimpin out on the alky to lean it out some but that just agve more KR. take out fuel, add alky. you are running pure denatured right? for example i am running 25 psi and 21 deg timing on full pump speed. gets rich when alky first hits but into 3rd the O2s get progressively leaner. ill just have to deal with this until Razor brings out his PAC. to test kit use test button. if it works engine should sputter. also take the car to turn on point and see if the O2s go real rich and it bogs. also more boost can cause more KR due to tire spin. i remember running 30 psi and getting like 29* KR from a dead punch but from a 55 roll punch it was 0* KR all the way thru 3rd (on a cool nite of course). decreasing timing can also be a helpful knock deterrant esp in hotter weather.

 

[turbo buicks]

also i see your sig it say polished heads and stock turbo ported out. ported turbo at 21 lbs may be out of its efficiency range and blowing hot air like a stock turbo/heads car at 23+ psi. i remember my friends TTA with P&P heads, big valves and cam could only run 16 psi on a stock turbo and he needed alky cuz the turbo was out of its range. 20 psi may be all you can get out of it. BTW, a .030 bore engine will have more compression than a stock bore engine IIRC. what were your O2s on your runs. your pushing those stk injectors id say. also at the higher airflow rates of the heads and cam your I/C has a higher pressure drop across it due to more CFM. this would cause a big increase in temps and inefficiency. i say get new injectors first and a bigger turbo and better intercooler next, your choice. efficiency is KEY!

 

[Turbo__Tim]

All good points made here. I don't have much to add except to point out that with the 'polished' heads you are possibly making the same potential for power as 22 psi stock heads.

Keep the boost 'down' to 20 psi. You are prolly losing power anyway by pushing the stocker beyond it's efficient range.

More boost doesn't mean more power.

The first run you didn't allow the cylinders to heat up. That extra 20 mph, and few seconds more run time in the second caused the 200* temperature rise that made the difference.

You need to lower the boost to 19 psi, and /or add 10-20 percent water to get through a quarter. You are almost there! Track times should tell you which of your favorite combinations is generating the most power.

Good Luck! And you should have an egt.

 

[Weazel]

Wow, good info you guys, thanks a lot! I didn't consider the ported turbo and polished heads...maybe it's moving more air than most stockers at 20+ psi. DS said that I was making 300 hp to the wheels at 3800-4000 hp, and 400 ft-lbs from 2800-3400 or so (if I remember the average of the 4 runs I made at 20psi). That was more than I was expecting...maybe I am pushing the turbo as is. That's a really good point...I hadn't thought of that possibility.
My O2s are 820-830 in 1st and 2nd, slowly dropping to 790-800 toward the meat of 3rd gear. I haven't taken her much over 80 (stupid speed limits), so on the track, running 105-110mph, I'd imagine o2s would go even lower. I don't wanna see much below 770 or so during any part of the run. The injectors are pretty well tapped based on DS.
The kit fires fine, the test light causes the car to bog, and it pushes about 38-40psi out of the alky tank at pump speed of 5.5 (where I had it before). I just wasn't sure I saw the light or heard the click of the pump coming on during the run...too many other worries doing 80+ on a back road. I'll try more pump speed first, and if I'm not seeing more power, I'll take her back to 20 psi where it was happy. I'd get knock at anything over 15psi without the kit, so it's still money VERY well spent if I can "only" run 20 or so with the stock turbo/injectors.
I definitely want a bigger turbo/inj combination ASAP, but I wanna get the most out of this setup before throwing in another variable. Thanks for all the good tips, I'll hopefully get it sorted out this weekend, and take her to a street night next week at the local 1/8th (but of course I'll 'stay in it' for a full 1/4...gotta love Direct Scan) Thanks! I'll keep ya posted.