marco_chevy

LS1 is the same timing of LS2, LS3 ?

29 timing is not for injected car?

Carburated LS2 can take more timing, as i can read at a lot of place!

I run a 750 Holley whit 72 and 76 jet, run 13.5, 13.8 cruise, and 12.0 12.3 WOT.. may-be this will change when the timing will be good. 70 is very too lean for me, on the primary, and 76 will drop to 75 when found the good timing.

I actually run the same timing as your, whit vacuum advance at 0 for each RPM. 0-1000=18, 1000-3000 go to 29, drop at 27 to 400, return to 29 at 5000, and stay 29 until the end. ( curve found on this forum) But i'm sure i can give more timing and have better performance.

DCx

iTrader: (12)

I have a FAST dual sensor wideband hooked up to the car at the moment. once i switched my jets to 70/80 and took 2* initial timing out my spark plugs cleaned up a lot. they are a nice light brown color *** opposed to the shitty wet/black plugs i was fouling when i was using my piece of **** rich mighty demon carb.

I have a busted 3rd gear in my t56 so i havnt been able to see what WOT readings are for the air/fuel with this tune but idle and cruise numbers are looking good.

Mike454SS

iTrader: (4)

Vacuum is going to be about the same at WOT as it is with the engine off. a normal vacuum gauge will show you O at WOT and 0 when the engine is off.

0 PSI is 29.92 inches of mercury (vacuum) and also 0 KPa and also 0 bar, and can be called an absolute vacuum, and 14.7 psi is 0 inches of mercury (vacuum) and 101.5 KPa and 1 bar...which equates to atmospheric pressure on earth, at sea level a 0 degrees celcius or 32 degrees farenheit. What a 1 bar map sensor is reading, it atmospheric pressure and below. When the throttle plate is closed, or partially closed, the engine wants to pull in more air than the throttle plate is allowing it to, so it creates a lower pressure in the plenum than the outside atmosphere, which we reference in vacuum or KPa, we tend not to think of it in PSI until we're above atmospheric pressure with a turbo or supercharger.

Normally, most V8's with stock cam's should (not always, but should) be able to pull more than 15 inches of mercury...probably closer to if not slightly more than 20...because the throttle plate is providing resistance to the engine breathing in air. At wide open throttle, the throttle plate should no longer be a restriction, and thus the pressure in the manifold should go right up to be almost equal to the atmospheric pressure. When the engine is shut down, it no longer wants to breath in any air, so the pressure equalizes on both sides of the throttle plate, wether it's open or closed.

In the same regard, a 2 bar MAP sensor has a total measuring range of 2 bar, or 29.4 PSI or 203 KPa...half of the range will be below atmospheric pressure and half of it will be above. A 3 bar sensor will read a total range of 44.1 PSI, 14.7 below atmospheric, and 29.4 above atmospheric.

marco_chevy

Ok, thanks a lot Mike454SS..

I understand better.. i was thinking that the pressure was 0inHG( 14.7 psi) at OFF, and 29in HG ( 0 psi) at WOT... now i know that is 0inHG (14.7psi) at motor OFF, and return to about 0inHG(14.7psi) at WOT... and will go to about 15-20inHG ( 7-8psi) whit motor ON and trottle plate closed.

for the gauge reading, i can see 0 at OFF, but for the rest, it's plugged between my booster brake and my vacuum tank( my last motor has very poor vacuum). So when motor run, i can see about 20, the peek vacuum that have in the tank.

Can you put number to my post #19...

If PSIa read by the MSD, whit pills #4 like the picture of the post #7, is 14.7 at WOT, it's mean that i will have, at 3500 rpm, 21deg + may-be 0 deg advance total of 21.. same for 5000 rpm, i will have 16 deg + about 0 deg, total of 16 ( very low timing). (if MSD at 14.7psi give + 0 deg). When cruising, at 3500 rpm, i will have the 21 degre + about 10 PSIa, give +5 degre more, total of 26 degre... ( very low timing again)

May-be at idle, 1000rpm, i will have about 6 PSIa, that's mean 4 deg + about 15 advance degre, total of 19 degre! 19 is ok for idle.

I know i can send a timing curve to my msd whitout any vacuum advance, but i want to have the advantage of the MAP sensor...

Normally, at cruise, for the same 3500 rpm, i need to have more timing or less timing ? i need to have about 29-30 timing or 39-40 timing?

I understand the vacuum, but need to understand the vacuum advance!

marco_chevy

this evening, i run my car, whit no map sensor, whit pills #1... it give 15deg at 3500rpm, 10deg at 5000 rpm, 13deg at 6000 rpm, and when the map is not connected, the default advance is 20... at all rpm... it give 35deg at 3500, 30 deg at 5000, and 33deg at 6000 and up... the car go very very very well... 32-33 degre is a very good timing..trottle response is very good and WOT it's run too rich at 12:1.. i will drop secondary from 76 to 75. i also run the pills 2, and it give 2deg more at all rpm, and the performance is not like the pills 1.. 35 deg is a bit too at 6000rpm... when i will have my map sensor, i will put 32-33 WOT, and i dont know hom many at cruise! may-be 10 more! for have a better fuel economy!

Mike454SS

iTrader: (4)

It sounds like pill #1 is the pill to run for now...you might want to look into customizing it further (I believe you can with the software included on the CD).

I'm sorry I can't put specific numbers to anything, but I think cruising at light throttle you'll want to see 38-40...and full throttle, I'd see how it feels with a little less than you have now...if 32-33 feels better than 35, I'd try 30-31 or even 28-29 and see how that feels too.

These engines do not run with as much timing as older Chevy V8's.

marco_chevy

i run 29 and 30 degre, and it go better, much better at 33... i will try 32, see what apen! but now, i'm happy whit this set-up.. i will add a MAP sensor only for have better fuel economie ate cruise...

Mike454SS

iTrader: (4)

I was helping a friend tune his car on the dyno this weekend, using the same MSD box. It made pretty much the same power at 29 degrees and 33 degrees on the dyno. Using LS6 heads on a 6.0 block.

marco_chevy

OK... I think the range is between 29 and 33 degre. In my case, i have L92 heads, all alluminium block and head. May-be all alluminimum engin can take 1-2 degre more... When i will have my pcima to rs232 adapter this week, i will chek if i really have 35 at 3500, 31 at 5000 and 33 at 6000 and up... for now, i can chek that MAP disconnected, i always have + 20 deg timing... but i did not chek this over 3500 rpm ( whit a home PC).

3pedals

iTrader: (3)

I dont understand why you have +20 degrees with your map sensor disconnected. it should not be adding any timing if the map is disconected, or even if the map is expossed to open atmosphere. You should only have the base advance curve in the pill your running, or program your running.
Soon I will get to mess with mine.........then maybe I can add real experience/advice to this thread.

marco_chevy

Ok 3 pedals, here is what i think: let me know if i'm wrong! 2 weeks ago, i have connected my home PC on the MSD box ( i'm waiting about a pcmcia to rs232 adapter, because my usb to rs232 did not work on my laptop). When i connect the msd box to my home pc, it was for send to the PC a timing curve whit 18 at 0 and 1000 rpm, and 29deg 3000 to the end whit all vac advance to 0, like i found on this forum( because i have no MAP sensor) Before i transfert timing curve to the msd box, the pills #5 was connected, and on my home PC, the timing was 22... pills 5 is 2 degre at 0 rpm, and advance +20 degre whit no MAP sensor connected. Like the PSIa was at 0... it give +20 degre.. ( refer to the post 7 ) it's why i can write that the ''default'' advance whit no map sensor connected is always +20 degre.. I will have a better reading whit my laptop on the car, for a couple of run, may-be this week. For now, the best pills i have running is the #1. The #1 run better than the 2, the 2 run better than the 3, and the 3 run better than the 4. I did not try the other....... Now, i'm running the #1, and work very good, very good anser, very good high rpm... the car go to 140mph very very fast... i'm faster than my friend whit is 347 stroker Mustang that run 12.50 at 113 mph last year..... it's why i can say the car run very nice!! I think it's impossible to have very great performance at only 10 deg at 5000 rpm, and only 13 deg at 6000 rpm....whit pills #1 and no vac advance. it's why i think it have always + 20 deg... it give 30 at 5000 rpm, and 33 at 6000 rpm...

I think the MSD box work like this, when no map sensor is connected. May-be the sensor not connected is like the PSIa is at 0... it give the +20 degre programmed in the pills!...

Dickie-311

iTrader: (1)

we made 407hp @ 29deg and 412 hp @ 33 deg and 408 hp @ 36 deg

3pedals

iTrader: (3)

you may be right. I wont know till july, when I get home, and can finally start my 6.0 for the first time.
I will share what I find, for sure.
Barrett

marco_chevy

Theses HP are at the wheels ? and 33 degres is the best result! like mine.. i'm sure that is the best timing for a carburated ls 6.0L. At the engin, it's about 17% more, give 480-485hp at the crank.

May-be i will have about this hp whit my 6.0L whit L92 head, and LSR compcam 54-469-11 and GMPP intake. Compa cam toldme min. 500 to the crank... i hope..

3pedals. when i will have my laptop connected, i will make 2-3 run and chek if the timing is very +20 at all rpm, whit MAP not connected. If yes, i will create my map whit 33 deg 3000 to the end, and add + 6-7 whit MAP sensor for have max 40 deg at cruise. I will write back whit the result.

marco_chevy

ok.. this afternoon, i make test.. i receive my PCMCIA to SERIAL adapter for my laptop, because the USB to SERIAL adapter did not work. this one work very great. i run the laptop in the car for a couple or miles... whit the map sensor not connected, the MAP reading is alway 1.1 PSI, it give always +20 degre at any RPM... it's why the car run great whit pills #1... it's really give + 33 at 6000 rpm.. I also receive a new MAP sensor from chandler motorsport on ebay, for only 35$, brand new. i connect it, and all work correctly. The map reading is 6 psi whit motor OFF, and also 6 psi whit motor WOT... at cruise, i can read between 2-3 and 4.. 2, 3 and 4 give + 20... 6 psi at WOT give +15....

I run pills #4, and the car run at 41( 21 + 20) deg at cruise at 3500 rpm. run 31deg WOT at 5000( 16 + 15) and 34 at 6000 ( 19 + 15) rpm. whit pills #3, it's -2 degre at each rpm. very nice.

I do my own curve, whit 20 at 3500 ( -1 deg whit pills #4, give max 40 deg ), + 18 at 5000 ( 2 more than the pills 4), and 19 at 6000, like pills 4... run very great. and run 39-40 deg on high way at 60mph - 3000-3200 rpm.



Map sensor never go under 2 psi, when cruise and turn off the fuel... and never go over 6.1psi WOT or motor OFF... work great.. i will have good timing WOT, and i will have better fuel economy at cruise..

xx_ED_xx

iTrader: (17)

I have a 6010 BOX ON MY 8.1 swap and the ls profiles were to aggressive. Unfortunately msd uses this wierd I guess european method of measuring vacuum etc on the data program. I can screen shot my tune when i get back to my laptop

3pedals

iTrader: (3)

I cant wait to try mine. But I think something is wrong with your MSD6012 if it reads 6.1psia with the engine off and carb throttle open. this is obviously what is causing the msd to add +20* of timing to your map!!!! It should read 14.7psia with engine off, throttle open. and when engine is running it should read about the same or a little less at WOT, and progressively less psia as the throttle is closed, to the smallest psia reading with the throttle closed, and engine at an idle.
Barrett

marco_chevy

1st, i did not try the motor OFF whit trottle open! i can not see the reading of the mdsd... but motor OFF whit trottle closed is 6. I really think the reading is very good.... the pills #4 have only 16 degre at 5000 rpm, and 19 at 6000 rpm... it'f the PSIa go to 14.7 at WOT, it's mean that the timing advance will be +0.... it's impossible that the car can run well at only 16 or 19 degre at WOT..... at 5000 or 6000 rpm!!! AT 6PSI, the advance is 15.. give 31 or 34 at 5000 and 6000 rpm... i think these number are excellent!

someone have run his car whit a MAP sensor and a laptop connected for chek the MAP reading. ? in my case, cruise is 2-3-4 psi ( + 20 deg) and wide open trottle at 5000-6000 rpm is about 6 PSIa.( + 15 deg)... and it give a good total timing.. about 39-40 on cruise and about 33 WOT... it's a very good timing curve! i think.

for the 14.7 PSIa..... it's every where or it change depend of the city, contry ???? i'm in Quebec, Canada!

3pedals

iTrader: (3)

OK I finally got mine running!! mine shows 14.1psia engine off with ignition on. I was not able to drive with the laptop connected as the laptop battery is toast and I dont have an inverter.

marco_chevy

Whit the trottle plate open? i dont understand why i only have 6 psia!!! but i can not figure that you can have good performance if you have 14 psia at WOT... whit pills #4, you will only have 16 deg at 5000 rpm, and 19 deg at 6000 rpm... and you need 32-33... you need to add 14-15 degre whit the vacuum advance!!! Try to find a inverter or a good battery and let me know the result when drive whit it.

What is the reading whit motor on, at idle? when you hit the pedal ?

My MAP sensor is a American standard AS59.