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boost limits on 93 octane

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Old 08-20-2008, 06:44 AM
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Default boost limits on 93 octane

im running a 6.0, forged rods/pistons, 9.2 comp, d1sc procharger, large procharger sheetmetal i/c, and a carb, w/8 rib conv.
i have been playing with diff timing settings, wonder what boost would be safe-i have seen around 12 lbs, using tr6 plugs, not sure how safe i am yet, i run the afr's pretty rich for now, but the plugs look a little hot, timing was around 29 degs total, but i think i have to back it down to get a better reading on the ground strap
Old 08-20-2008, 06:54 AM
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Originally Posted by forcd ind
im running a 6.0, forged rods/pistons, 9.2 comp, d1sc procharger, large procharger sheetmetal i/c, and a carb, w/8 rib conv.
i have been playing with diff timing settings, wonder what boost would be safe-i have seen around 12 lbs, using tr6 plugs, not sure how safe i am yet, i run the afr's pretty rich for now, but the plugs look a little hot, timing was around 29 degs total, but i think i have to back it down to get a better reading on the ground strap

You are running 12lbs of boost on 29 degrees of timing and havent blown the motor!! dam lucky... I would back on the timing...
Old 08-20-2008, 07:17 AM
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Even on really good fuel that is a recipe for disaster. I would start at 14 and work my way up. If the plugs are not closing the gaps every pass right now then that is more then likely not your actual total advance.
Old 08-20-2008, 10:42 AM
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Are you using a MSD 6010 for your timing control? If so, do you use a timing light to verify the timing?

A stock LSx engine is between 25-27 degrees at WOT, so 29 degrees on a stock LSx with boost is very problematic on pump gas.

I run 8:1, 348ci, 15 psi, on 93 pump gas, and timing is around 19/20 degrees at WOT. I've not run the car this way at the track but the buttometer tells me that the car is high 9's low 10's. I figure I might be making 700 crank hp, maybe 650 hp.

I would run NGK TR8's or equivalent, and verify the timing and reduce it to 15-18 to baseline.

Edit, I saw a post somewhere where you said the car runs crappy, maybe you can elaborate. Might have been on YB.
Old 08-20-2008, 11:53 AM
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wow thats allotta timing
Old 08-20-2008, 04:22 PM
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guess i have been lucky, lol-i did a postive stop, used a timing light today, msd6010 is dead on-used to gen 1 and b/b procharged motors where i ran higher timing-i dialed in a new timing today, a lot lower-maybe thats why i had the headers glowing
the car runs great on the street, busting the tires off in 1st and 2nd
orig had problems with the engine, acted like a bad valve or ignition, i switched to a more agressive pump cam in the carb, cured it-just never felt like a fuel problem
tomorrow is dyno day, looking for a safe tuneup
Old 08-20-2008, 08:36 PM
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I wouldnt even run that much timing on C16.........................
Old 08-21-2008, 12:34 PM
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i got back from the dyno testing this morn., didnt hit the #'s i was hoping to, but was more interested in a safe tune-the guy running the dyno was able to use my laptop and set it up with the map sensor-at 6200, i was at 488 rwhp,
around 5500 the torq was 431-we data logged a bunch of stuff, boost b4 the carb hat, and boost in the intake(12.6/9.8), intake air temp after the intercooler(100 degs) fuel press rise with boost, afr's
we were down to around 20 degs total advance under boost, afr's were around 11.6-i pretty much hit the carb mods on the nail, only made one chg to it.
did see some belt slippage, but curve was nice, all the way up-we pulled a plug from each side after every pull, looking at the timing and jetting
prob could have moved the timing up a little more, but wanted to stay in the safe zone-theres more power to be had for sure, prob the 2.5 full exhaust isnt helping, and a better air intake deal, colder plug, etc, but the old chevelle runs and drives so good i will prob just leave it alone for now
Old 08-21-2008, 03:40 PM
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What transmission?

My old blower setup did 680rwhp and went 9.40 @ 3500 raceweight, so if you made 488rwhp you could potentially go mid to low 10's at 3400-3500.
Old 08-21-2008, 03:42 PM
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boost.....timing........



Im having deja vu !!!!!!!!!

Pump gas isnt the limit....but tune it safely ;-)
Old 08-21-2008, 04:57 PM
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im running an old school switch/pitch turbo 400, dual stall, 1300/3000
im only running 3:55 rear gears with a 28" tire, plus the converter isnt really matched to the rear/cam, but i like to drive it and not hear the flowmasters killing my ears, lol-but this winter i might step up with my 4l80e, better gears
kind of was an experimental setup for now, using the vette front dr and procharger setup, now that i know it all works, 408!!!! lol
going to a track rental next month, might make some minor changes, those 3:55's are kind of noisey, lookin to take on a 572/720 crate car!!!!!
this car is a step down from the 489 b/b chevelle with an f1r procharger i had, but more fun to drive, doesnt bust them loose all the time in high gear
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Old 08-25-2008, 06:40 PM
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Originally Posted by Pro Stock John
What transmission?

My old blower setup did 680rwhp and went 9.40 @ 3500 raceweight, so if you made 488rwhp you could potentially go mid to low 10's at 3400-3500.
Mid to low 10's on 488 rwhp? I have seen all motor vettes barely run in the 10's with a big cube motor making 500 wheel threw a auto. I dont see how you figure hes going to do low 10's on that power level. And if he does have a chance to go that fast the only way hes gonna get there is so really fast 60foot times. 488 wheel isnt that much power I had a turbo stang that would run mid 10's weighing in at 3450 with me in it making 600whp tell me how you figure so fast with that power. Cars gonna have to be alot lighter then 3400 pounds or have more power.
Old 08-25-2008, 08:42 PM
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Depends on the combo, and most of the time A2/A3 dyno numbers are 100 off from a locked A4 or M6 setup. But 500rwhp with an A3 is good for mid 10's with the right combo.



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