In a few weeks, my setup will be complete. Its pretty simple. T3, custom manifold, walbro 255lph in tank pump, and an sds eic (extra injector controller). I will be running 450cc's for the extra injectors. I will be running 6-9 lbs. 6 for daily and close to 9 at the track. Now my friend tells me that I will want to pull some timing. I've also heard that I'll have plenty of fuel and that won't be neccessary (the ecu will compensate), but the ecu can't read boost...right? So hes saying that leaving stock timing will increase wear on the ringlands, etc and cause they to go. Is this true? I know it would be a good idea. However, I really don't feel like shelling out the 300 for the dis-2 but at the same time, I wanna be safe and dependable. Thanks for the help
1998 Cavalier Z24
Getting Boosted!
You should pull some timing specially with the motor being stock built, at least about 2-3-4 degrees, nothing higher than that.
This is an expensive hobby man.
SunCavi
Best time:"""11.946""" @ 114.73 mph @17psi 1.83--60"
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13's
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so youre boosting eh ? nice man i want a ride
what he said. dis-2
Vice President - NEJBody
2007 Cobalt SS
2001 Sunfire (retired)
u wont need to retard timing at all if u tune the extra fuel correctly
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234 HP and 239 TQ at 7 psi
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SunCavi wrote:You should pull some timing specially with the motor being stock built, at least about 2-3-4 degrees, nothing higher than that.
This is an expensive hobby man.
SunCavi
2-3-4 degrees... what should determine those #'s?
Power? Boost? Heat in the combustion chamber?
-Chris-
-Sweetness-
-Turbocharged-
Slowly but surely may some day win this race...
He is going to run 9 PSI and not retard the timing, well good luck.
Power doesn't have anything to do with it and not boost.
Heat in the CH has.
Besides the main factory is a good night of sleep knowing that you have less chance of pre-igniting.
He can do whatever he want, blow his motor for all I care.
SunCavi
Best time:"""11.946""" @ 114.73 mph @17psi 1.83--60"
11 second daily driver!!!!
Race Related 727-561-9440
Shop of choice for your 11 second J body!
Also, built bottom end and or top end LSJ and L61's available.
13's
----12's
----11's
----10's
BTW, we all have our own way of looking at different things so I am just giving you an opinion.
Others believe it differently, so it is up to you to believe to whoever.
Like people saying ''go with high compression and Turbo it WILL be a LITTLE HARDER to tune''' my ass. Speaking from experience.
SunCavi
Best time:"""11.946""" @ 114.73 mph @17psi 1.83--60"
11 second daily driver!!!!
Race Related 727-561-9440
Shop of choice for your 11 second J body!
Also, built bottom end and or top end LSJ and L61's available.
13's
----12's
----11's
----10's
pulling timing is an excuse for not using as much fuel....or not being able to use as much fuel...
actually correction.......use a higher octane fuel and u will not have to retard timing. 93 octane and u may be able to get away w/ 9 psi and not pulling timing.
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234 HP and 239 TQ at 7 psi
Come check out what I have for sale!!!
Josh wrote:u wont need to retard timing at all if u tune the extra fuel correctly
SunCavi wrote:You should pull some timing specially with the motor being stock built, at least about 2-3-4 degrees, nothing higher than that.
This is an expensive hobby man.
See this is what I mean, people are telling me different things so i'm a little confused of what to do. I've heard both of these responses equally from probably 20 different people. I'm just trying to get opinions.
Shifted (KickAzz) wrote:Nope, ECU won't compensate. What are you using to control those extra 440cc injectors?
I know the ecu won't compensate. Thats what I said. I know the ecu won't read boost. I'm going to be using an sds eic to control the two extra 450's, not 440's.
Keep the replies coming, thanks guys.
1998 Cavalier Z24
Getting Boosted!
coming from someone actually having experience running high boost on these cars....u dont need to retard timing. just use good gas when ur gonna up the boost. i ran 16 psi on my car for a long time and never pulled any timing.
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234 HP and 239 TQ at 7 psi
Come check out what I have for sale!!!
MSD. Then you could run upwards of 13psi
(Not responsible for any blown engines from this comment)
O noes!
Quote:
coming from someone actually having experience running high boost on these cars....u dont need to retard timing. just use good gas when ur gonna up the boost. i ran 16 psi on my car for a long time and never pulled any timing.
Well,,, yer kind of backwards. You had to use too much fuel to cover too much timing. Reducing timing allows you to run less fuel and make the same power.
If reducing timing under boost weren't important, GM wouldn't have spent the time and money to do this on boosted factory cars. They reduce timing as intake air temps increase and they reduce timing as boost increases.
Look at how many people on this list think you can't run 14.7:1 under boost. Well, you can't if you're running too much timing. But there's no practical reason why 14.7:1 won't work for a boosted engine. My 2 turbo cars do that every time they're driven.
Better to install something to retard timing than burn up the engine.
-->Slow
slowolej wrote: You had to use too much fuel to cover too much timing. Reducing timing allows you to run less fuel and make the same power.
I think this is the most important part for you to consider.
If you dont like running like a pig on gas when you're up high under boost, try retarding the timing to compensate for combustion chamber temps. Thus lessening the need for as much fuel.
Its actually up to you whether or not you should retard timing.
On a stock engine, do you really want this one to last, or are you going to rebuild it anyway?
I think you need to make the decision yourself, given the parameters that have been put forth on this page.
<a href="http/www.cardomain.com/id/stevefire23">stevefire23</a>
No, I sure as hell don't want to push it on this engine and I want it to last. I just spent the money for a new motor and h.o. tranny, I sure as hell don't want to be rebuilding andtime soon.
1998 Cavalier Z24
Getting Boosted!
Im kinda in the same boat, im gonna get 2 extra injectors (440cc), fmu, fpr, intake high pressure pump, and a t3/04 48 trim. I also have plans for around 6 psi, would that be safe to do all that and retard the timing? I was kinda mayb hoping to do this as i save for an engine build.
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Retarding the timing is done to reduce chamber temps; so is adding more fuel. EGT and A/F ratio are both factors in this. High temperatures cause predetination, adding fuel is the answer to compensate for the extra air and make you not run lean/hot. Like everyone else said, you can run without pulling timing, but you need to add more fuel if you do this. If you can tune with both a true A/F reading and an EGT reading then you can pretty much go about it anyway you want.
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Myspace
pulling timing raises EGT temps. Pulling timing isn't the answer. adding more fuel is.....i wasnt just dumping a bunch of fuel in. I knew what my EGTs were supposed to be and added or took away more fuel based on that. Pulling timing is an excuse for poor tuning.
also...gm pulled timing on their new motors for reliability issues. I can gurantee you the stock fuel/timing maps on the car are very conservative. They could probably advance timing, add some fuel, and pick up some power.
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234 HP and 239 TQ at 7 psi
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Quote:
Pulling timing is an excuse for poor tuning... the stock fuel/timing maps on the car are very conservative.
I would agree that GM's tuning favors reliability. But they don't pull timing because they're poor tuners. The amount of cylinder pressure before the spark event has always been a major factor in setting optimal ignition timing. With fuel remaining the same, decreasing cylinder pressure slows the burn rate while increasing cylinder pressure increases the burn rate. Forcing VE greater than 100% with a turbo or supercharger increases the effective compression ratio, which increases the burn rate, which in turn suggests that less timing is required. If you choose not to adjust timing and add fuel instead, you replace available oxygen with fuel. The first thing this does is slow the rate of burn in the cylinder. You see lower EGT's in part because you're not actually burning as much fuel, in part because the remaining unburnt fuel is absorbing heat energy. The second thing you do is reduce the power output because there isn't as much available oxygen to burn. Now I'm not saying that you weren't making good power, because I've seen plenty of strong dyno runs and plenty of fast cars that follow the "add fuel" approach. But too rich mixtures decrease the engine's power level.
Reducing timing to less than optimum can increase EGT considerably. You start the burn later and it will end later. If you start late enough, the exhaust valve will open while the mixture is still burning, pushing combusting fuel and air into the exhaust manifold. This can be desirable to some extent... some people will sacrifice a little acceleration to build boost faster. Once boost is at the desired level, timing is brought back up to optimum to keep EGT from climbing dangerously high and to deliver more energy to the crankshaft. If you're using too much fuel to begin with, reducing timing can raise EGT for the same reason, unburnt fuel and air are pushed into the exhaust (remember that richer mix = slower burn). In these cases, reducing the amount of fuel used along with spark timing will usually cure the problem. It's a balance game with both timing and fuel playing an equally important part. Tuning is the process of finding a balance. Good tuners try to find the best balance.
RPM based ignition advance is only needed because the amount of time available for the fuel/air mix to react decreases as engine speed increases. The whole point of adjusting timing and fuel is to bring the point of peak cylinder pressure to about 12 - 15degrees after piston TDC. By rights, you would be adjusting the beginning of the burn according to when peak pressure occurs. Now I don't know how you determined the optimum EGT, but I know that you cant just say "My EGT needs to be this much" for the car and expect to get the best results. You can keep EGT below a dangerously high point, but it's up to the engine, not you, to decide what the exhaust temp is when the engine's performing at it's best.
As far as it goes, GM couldn't possibly add fuel to the turbo Sunbird calibration to make more power. That engine used waay too much fuel in stock form. I own 8 cylinder cars which used less fuel than that one when I bought it. I reduced fuel under boost and timing in a few key areas, and the it responded very well.
Props for what you've already done. Keep an open mind and you'll get better.
-->Slow
if you have an intercooler and use a wideband to get it tuned right, i wouldn't bother. i ran 10lbs plenty times with no problems at all. summer ill hopefully be at double that with still no timing retard. just keep the a/f's good and the intake temps down as much as poss while using at least 93 oct gas and you should be good to go.
12.6 @ 114.6 MPH
slowolej wrote:Quote:
Pulling timing is an excuse for poor tuning... the stock fuel/timing maps on the car are very conservative.
I would agree that GM's tuning favors reliability. But they don't pull timing because they're poor tuners. The amount of cylinder pressure before the spark event has always been a major factor in setting optimal ignition timing. With fuel remaining the same, decreasing cylinder pressure slows the burn rate while increasing cylinder pressure increases the burn rate. Forcing VE greater than 100% with a turbo or supercharger increases the effective compression ratio, which increases the burn rate, which in turn suggests that less timing is required. If you choose not to adjust timing and add fuel instead, you replace available oxygen with fuel. The first thing this does is slow the rate of burn in the cylinder. You see lower EGT's in part because you're not actually burning as much fuel, in part because the remaining unburnt fuel is absorbing heat energy. The second thing you do is reduce the power output because there isn't as much available oxygen to burn. Now I'm not saying that you weren't making good power, because I've seen plenty of strong dyno runs and plenty of fast cars that follow the "add fuel" approach. But too rich mixtures decrease the engine's power level.
Reducing timing to less than optimum can increase EGT considerably. You start the burn later and it will end later. If you start late enough, the exhaust valve will open while the mixture is still burning, pushing combusting fuel and air into the exhaust manifold. This can be desirable to some extent... some people will sacrifice a little acceleration to build boost faster. Once boost is at the desired level, timing is brought back up to optimum to keep EGT from climbing dangerously high and to deliver more energy to the crankshaft. If you're using too much fuel to begin with, reducing timing can raise EGT for the same reason, unburnt fuel and air are pushed into the exhaust (remember that richer mix = slower burn). In these cases, reducing the amount of fuel used along with spark timing will usually cure the problem. It's a balance game with both timing and fuel playing an equally important part. Tuning is the process of finding a balance. Good tuners try to find the best balance.
RPM based ignition advance is only needed because the amount of time available for the fuel/air mix to react decreases as engine speed increases. The whole point of adjusting timing and fuel is to bring the point of peak cylinder pressure to about 12 - 15degrees after piston TDC. By rights, you would be adjusting the beginning of the burn according to when peak pressure occurs. Now I don't know how you determined the optimum EGT, but I know that you cant just say "My EGT needs to be this much" for the car and expect to get the best results. You can keep EGT below a dangerously high point, but it's up to the engine, not you, to decide what the exhaust temp is when the engine's performing at it's best.
As far as it goes, GM couldn't possibly add fuel to the turbo Sunbird calibration to make more power. That engine used waay too much fuel in stock form. I own 8 cylinder cars which used less fuel than that one when I bought it. I reduced fuel under boost and timing in a few key areas, and the it responded very well.
Props for what you've already done. Keep an open mind and you'll get better.
-->Slow
Wow, that pretty much sums it all up in my eyes. Thanks for the big writeup.
1998 Cavalier Z24
Getting Boosted!
--Glowin Cavy-- wrote:if you have an intercooler and use a wideband to get it tuned right, i wouldn't bother. i ran 10lbs plenty times with no problems at all. summer ill hopefully be at double that with still no timing retard. just keep the a/f's good and the intake temps down as much as poss while using at least 93 oct gas and you should be good to go.
I will have an intercooler along with all the neccessary fuel mods. I realize I probably could run 10lbs fairly often, but the objective here is to be safe. You have to ask yourself: "How long will my engine take the boost i'm throwing at it?" You can't expect and engine to take 10lbs forever. I don't want to be looking for yet another motor anytime soon. Been there, done that.
1998 Cavalier Z24
Getting Boosted!
ummm the only stupid question is one not asked and not meaning to jack this thread but... how in the hell would he pull his timing? with the stock ecu in place ???
"dude, thats a girls car"
you could use a msd dis2 or a greddy emanage to pull timing if u have one of them i dont plan on retarding timing unless i go past 10 psi.
