Decreasing spool time with tuning
Decreasing spool time with tuning I would like to start a discussion on the basis of optimising the tune, i.e. VE and timing advance for spoolup. Please list some ideas, what you have tried, or what works. On the Haltech i use in the RX-7, it has a quick spool command, which i have set to pull 18degrees of timing and add 20% fuel. This works awesome and i can get 8psi with a GT4202 on a 13B rotary. I would love to try this on my LSx, but would like some input, maybe a scan or something to show how you achieved this without affecting the drivability. Discuss!
Gary
Gary
hmmmm,,,,,my 4l80...2400 stall...2step set to 3500......-20 deg of timing deducted from my regular timing slowed spool. + 15 degrees timing over regular timing didnt seem to spool any faster so i guess i will leave it as is. with the regular timing and also with the +15 degrees, it reacted a lot faster off the tbrake as well. there is my unscientific driveway test on my combo from 20 minutes ago 
yeah i dont think theres gonna be a whole lot of input on this type of thing. How it works in the rotary is it dumps an assload of fuel in there, then fires it right before the exhaust stroke, effectively giving you combustion in the headers, and turbine housing. if you stay on it for say 10sec, the header starts to glow red pretty quickly. The problem doing it with the stock PCM, is you would have to be in OLSD, otherwise the computer wont let it put the fuel in, as the fuel is what really gives you the hit. Actually heres a video of it in action, no footbraking, just holding it at 1/2 throttle and pushing the button down on the RX-7.
http://youtube.com/watch?v=WC5YJgW6I4A
Anyway, any other suggestions?
Gary
http://youtube.com/watch?v=WC5YJgW6I4A
Anyway, any other suggestions?
Gary
With a manual transmission you want to retard timing and dump fuel so that it burns into the exhaust. This helps spool the turbo with no load.
With an automatic you want to "get up on the converter". In order to get the converter to stall higher and start the cycle you need torque. Pulling timing on an automatic car will result in poor spooling.
I've personally experimented with both methods when I was 6spd and now as an automatic. I've had great results with adding timing in the areas where i'm sitting on the transbrake to get it to initially build the first few psi and start the cycle.
With an automatic you want to "get up on the converter". In order to get the converter to stall higher and start the cycle you need torque. Pulling timing on an automatic car will result in poor spooling.
I've personally experimented with both methods when I was 6spd and now as an automatic. I've had great results with adding timing in the areas where i'm sitting on the transbrake to get it to initially build the first few psi and start the cycle.
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Verdad Gallardo nice having a long enough driveway to play on huh! Also thanks for the info. I have tried adding timing under load, and that seemed to work somewhat. Zombie, thanks for the info. Anyway, with this cam i have, (N/A), and this stupid stock stall converter in the 4L80, i just cant get moving until 3500, when the cam starts to come in. I know I know, i need a stall. Would rather have a decent set of brakes first though. Cablebandit or anyone with a 4l80, what you have for brand, cost, rpm of converter. I see that fuddle sells a nice one for $650 or so. Since its a footbrake car, im thinking a 32-3400 and a 3.23 rear gear.
Gary
Gary
Some ways to get faster response is lighter flywheel in manual cars. Also my dsm programs have something called antilag to bulid boost in manual cars and no lift to shift stuff to keep them spooled between shifts. Other things that can help spool faster are smaller turbos, bigger displacement engines and playing with cam timing. Too rich can also slow spool .Timing not sure it makes all that much diference. Read low timing can make more heat and help but not sure thats true.
Autos you can go with stall converters of course. Mainly its your combination you have chose that will affect spool up the most. Size of engine and turbo wheels specs and ar and all that stuff.Faster spool usually less top end. Bigger turbos more power but slower spool. And on a manual downshifting of course will get you into the spooled up state quicker.
Autos you can go with stall converters of course. Mainly its your combination you have chose that will affect spool up the most. Size of engine and turbo wheels specs and ar and all that stuff.Faster spool usually less top end. Bigger turbos more power but slower spool. And on a manual downshifting of course will get you into the spooled up state quicker.
i have a fuddle 2400...whatever his best one is. it starts blowing thru at 10psi though so eventually i will get another converter. I have a tbrake so the low stall is for the daily driver part. the rossler tbrake is the ****. He just helped me mod mine so it reacts a lot faster than his first gens did which is what i have
A 2step will help with the spool on an auto car and also retarded timing should help no matter 6spd or auto. By retarding the timing you are allowing unburnt gas into the exhaust which will then cause heat = spool. With a 2step at 3k I could get about 5psi but then when I took out 10 degrees of timing i saw 12psi. I know if you take out too much timing you will then negate this property and also cause issues when the timing kicks back in.
Depending on what ecu/software you are using you can log the areas of your spool and add some fuel at the same time as taking out timing and see what happens.
Being on a tbrake alone you will still see it taking a few seconds to spool since you are slowly loading the motor up but if you were to use a 2step as well you should see near instant spooling to a certain level based upon your rpms
Depending on what ecu/software you are using you can log the areas of your spool and add some fuel at the same time as taking out timing and see what happens.
Being on a tbrake alone you will still see it taking a few seconds to spool since you are slowly loading the motor up but if you were to use a 2step as well you should see near instant spooling to a certain level based upon your rpms
Originally Posted by cablebandit
hmmmm,,,,,my 4l80...2400 stall...2step set to 3500......-20 deg of timing deducted from my regular timing slowed spool. + 15 degrees timing over regular timing didnt seem to spool any faster so i guess i will leave it as is. with the regular timing and also with the +15 degrees, it reacted a lot faster off the tbrake as well. there is my unscientific driveway test on my combo from 20 minutes ago
How much boost does it build at 3500rpm?
Originally Posted by Phil99vette
Everyone I have talked to said to lean it out and add timing for an automatic.
Phil
Phil
Originally Posted by chevyls10
retarded timing should help no matter 6spd or auto. By retarding the timing you are allowing unburnt gas into the exhaust which will then cause heat = spool.
Hope that makes sense.
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Joined: Nov 2003
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From: Norn Iron
Originally Posted by Grr
I would like to start a discussion on the basis of optimising the tune, i.e. VE and timing advance for spoolup. Please list some ideas, what you have tried, or what works. On the Haltech i use in the RX-7, it has a quick spool command, which i have set to pull 18degrees of timing and add 20% fuel. This works awesome and i can get 8psi with a GT4202 on a 13B rotary. I would love to try this on my LSx, but would like some input, maybe a scan or something to show how you achieved this without affecting the drivability. Discuss!
Gary
Gary
), and is generally reserved for launch, or when you close the throttle between shifts to keep boost up ( secondary idle air bypass required if using between shifts )
Originally Posted by Zombie
Forgot to add the part about leaning it out helping too
Hope that makes sense.
Hope that makes sense.
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Joined: Nov 2003
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From: Norn Iron
If you could heavily retard the timing on the transbrake, that would fire out past the exhaust valve while it was open, and boost could be almost instant ( anti-lag )
Obviously do this with caution.
If someone could devise a method of using the KR function via a switch, to activate such ign timing....that would be one way to get it to work ?
How could the secondary/low timing map/table be activated manually ?
Obviously do this with caution.
If someone could devise a method of using the KR function via a switch, to activate such ign timing....that would be one way to get it to work ?
How could the secondary/low timing map/table be activated manually ?