How much timing in boost do y'all consider safe?
06-05-2007, 12:15 PM
#1
How much timing in boost do y'all consider safe? At 6ish PSI, I was dyno-tuned at 18 degrees of timing. I own HP Tuners and just bumped it up to 19 with no problems. AFR is about 11.3:1 currently.
My IATs are usually about 15 degrees above ambient so possibly on a really hot day down here in TX it could retard timing, but what have y'all seen to be a good number at similar boost levels...still on the conservative side.
93 octane...stock LS1 CR and internals other than valve springs.
My IATs are usually about 15 degrees above ambient so possibly on a really hot day down here in TX it could retard timing, but what have y'all seen to be a good number at similar boost levels...still on the conservative side.
93 octane...stock LS1 CR and internals other than valve springs.
06-05-2007, 02:10 PM
#5
On what CR though speedracer? I'm wondering...can I go up to 20 degrees of timing without any issues? It's SOOOO hard if not impossible to listen for knock when the wastegate opens and the turbo screams like a bancheeeeee!!!
I should throw some race gas in there, bump it up a few degrees and see what she'll do
.
I should throw some race gas in there, bump it up a few degrees and see what she'll do
.
06-05-2007, 02:56 PM
#6
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Correct me if I am wrong here, but your car has a knock sensor on it, why not just look at the logs after a couple of pulls and see what it is doing. Tune it on a hot day with bad conditions, add timing until it starts to knock a little and then pull some back out. We have done that on plenty of our old sbc stuff and all we did was add a knock sensor off an obd2 car hook it up to the datalogger. It worked fine for us. I don't see why it would be any different on your setup. Disclaimer, make sure that your sensor is good and don't make bold adjustments.
btw, your sensor should pick up the knock way before you can hear it.
btw, your sensor should pick up the knock way before you can hear it.
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06-06-2007, 07:02 AM
#9
Originally Posted by ss53mech
Correct me if I am wrong here, but your car has a knock sensor on it, why not just look at the logs after a couple of pulls and see what it is doing. Tune it on a hot day with bad conditions, add timing until it starts to knock a little and then pull some back out. We have done that on plenty of our old sbc stuff and all we did was add a knock sensor off an obd2 car hook it up to the datalogger. It worked fine for us. I don't see why it would be any different on your setup. Disclaimer, make sure that your sensor is good and don't make bold adjustments.
btw, your sensor should pick up the knock way before you can hear it.
btw, your sensor should pick up the knock way before you can hear it.
On our modern 'effiecient burn' cylinder heads, simply adding timing till it knocks does not guarantee the most power, in fact it usually costs you a few while decreasing effeciency and increasing pumping losses. Finding MBT is the key, and in many cases on quicker burning heads, it's well before the knock threshold. This is where tuning with a load-holding dyno is key togetting the most out of an engine.
06-06-2007, 09:01 AM
#10
Originally Posted by VTC_WS6
On our modern 'effiecient burn' cylinder heads, simply adding timing till it knocks does not guarantee the most power, in fact it usually costs you a few while decreasing effeciency and increasing pumping losses. Finding MBT is the key, and in many cases on quicker burning heads, it's well before the knock threshold. This is where tuning with a load-holding dyno is key togetting the most out of an engine.
Keith
06-06-2007, 10:31 AM
#12
Check out this thread I made a while back; same subject and some good info in there. https://ls1tech.com/forums/forced-induction/623534-turbo-guys-tell-me-about-your-timing-cr.html
06-06-2007, 10:44 AM
#13
At 19 degrees of timing, there was no knock on the data logs. 18 at this point was really conservative so I figured a way to pick up 5 or 7 hp would be to bump it a notch. So far so good...I would say it feels a little faster.
I think I'm bleeding off boost somewhere. At some point, I need to crawl under the car again and check the piping...do a pressure check, etc. After laying on my back for like 2 months working on the car, I was hoping to not do that again...guess I was wrong...again!
I think I'm bleeding off boost somewhere. At some point, I need to crawl under the car again and check the piping...do a pressure check, etc. After laying on my back for like 2 months working on the car, I was hoping to not do that again...guess I was wrong...again!
06-06-2007, 01:36 PM
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Originally Posted by VTC_WS6
On our modern 'effiecient burn' cylinder heads, simply adding timing till it knocks does not guarantee the most power, in fact it usually costs you a few while decreasing effeciency and increasing pumping losses. Finding MBT is the key, and in many cases on quicker burning heads, it's well before the knock threshold. This is where tuning with a load-holding dyno is key togetting the most out of an engine.
