need your suggestions on knock issues

[msheller]

need your suggestions on knock issues...short term fixes(quality alcohol inj kit? and cold air setup?)(I wanna race again in november), ...and long term as $ is saved(A2A....alum heads?)

my setup:

pte52 kit, 50's, 2800 vigilante, 3 bar, twin fuel pumps, phil long chip for stock motor and 50's, gm blaster coil, cr42ts plugsat .028, open dump for track, 160, wrapped dp, stock tranny/ic/motor, screen over turbo(sucking hot ai)r....12.7/106/20psi with massive tirespin w/ all 4 tires for whole 60ft.....new tires are on since that ordeal...think that's solved...I think w/ cooler mats and traction its got 11's in it...I can feel it

my issues:

I could use your suggestions again...

overall I love the "new" sy and drive it often...12.7/106 at 20 psi with full sunoco supreme112...so far with horrible mats... starting at 88and ending at 188!!! and note ridiculous 4wd tirespin the whole first 60ft..even with a conservative 1psi launch...I mean the whole way...its iceskating...I got new tires so it seems like I'll drop tons of time when I actually hook up....couple of things going on though...what do you think?

-mat temps increase to over 180 at greater than 90mph at the strip... at that time multiple knock kicks in (2-3 immediate/bak2bak counts with 10-20 degrees retardaround 100mph)..... knock seems well controlled until end of pull...and coincides with hi mat temps...when I noticed that, i went home thanking the god of intact motors for his grace...I sweaqr i can feel the power getting killed as a result of/as the mats increase.

-if i floor it from a standstill with no brake stand it bogs...small but annoying streetability issue...chip was tuned for smaller turbo?or?????

-if I push throttle to about half, then let off semi quickly or quickly..it act like a momentary cutout...again small but annoying

could the 50# "stock motor" Phil long chip actuallyhave been tuned for A2A or a smaller turbo or aluminum heads or something else that would cause me to fight with knock so much on my L2A and stock head truck? is my "hot air" intake part of the problem?

I'm seriously considering careful install and tuning with snow's adjustable/progressive alcohol injection....(race gas is too expensive, especially since i like to drive the truck 4-5 X per week... and I'm gonna fab a cold air intake this weekend...got my first baby on way and no$ for biggies like A2A or race gas or alum heads yet....)seems like that'll(alcohol) solve both mat issues and knock issues from research/others reports..and maybe aloow me a little extra boost to boot....I don't have any easy way to reburn or have chip properly reburnt...even though phil has offered to do so..(he has been very helpful)..my datalogging capabilities and setup are too old...diacom...so I'm gonna work with the chip i have if I can...carefully avoid excess knock thru whatever means i can for now..(alcohol!?, and cold air intake).and grow into this aggresive tuned chip eventuallly and properly with aluminum heads and A2A later....sound like a decent plan? other ideas?

Matt

 

[Windedv6]

Re: need your suggestions on knock issues

There is no reason you should have to run 112 octane. You really need to knock down those intake temps. I take it your are using stock heads and pistons? Feel lucky you still have a motor. I popped my stocker 5 years ago screwing with high intake temps and knock. It goes in an instance. Usually broken ring lands. Get those temps under 150*. Vortec heads and better pistons can survive the heat and some knock beating, but I think you are skating on thin ice with the stock setup.

Where is your timing at 20# and what is your actual afr? Phil will do you right with a chip but the chip doesn't know how much fuel pressure you are set at. Make sure your are satisfied with the fuel pressure setting. Is your voltage staying up at WOT. If your voltage drops then your pumps will put out less pressure. Frankly, you are better off running one 225 walbro than the two or get an.external. Two pumps drain alot of ampere at high pressure which drops the voltage. If your running other aftermarket electrical mods, and a stock alternater, some of your high temp problems and knock may be electrical related. I have been there myself.

I suggest you check out everything possible to bring down the temps which will help the knock,before yoyu go to the alky system. Then get the alky system to lower your octane fuel requirements and not to just cool down temps that may be caused from something fixable.

John

 

[SeattleSy#1255]

Re: need your suggestions on knock issues

I think you need to hold off on the alki thing...there are tons of things you can check before going with alki. Don't use it as a bandage.

I agree, get those IC temps down. I can't imagine getting those numbers from a properly working IC system. I'd check all your hoses and make sure there are no kinks in them...when you are done, recheck them 5 more times. Your IC pump should be checked and if you are running a stocker, upgrade that first.

I don't know where to begin with the multitude of thing to check but I guess you can start there. Alki will certainly help your IC temps, but get them down naturally first through a properly working IC system.

...and yes, you can literally feel the power drain from the timing retard.

I have been fighting false knock and it's irritating as hell when you can't track it down.