? Timing out of boost for low compression motors
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Teching In
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From: Irving, Texas
? Timing out of boost for low compression motors Is there any rule of thumb without using dyno to get close to optimum timing while driving out of boost? I know cam, heads, pistons, etc. have major effect on timing.
Could low compression motors 9:1 or less use substantially more timing in non boost areas?.
Assume engine as in my sig below with approx. 9:1 compression. I have been street tuning this vehichle for quiet some time (turned into hobby) and still experimenting with timing in the lower rpm areas. Seems like the more timing I throw into it the better it responds.
My timing while in boost is about as good as I can get (seat of pants) without KR and have both summer and winter considerations built in. I know the timing in off boost areas seems very high compared to many files I have seen on this forum.
Can someone please take a look?
Could low compression motors 9:1 or less use substantially more timing in non boost areas?.
Assume engine as in my sig below with approx. 9:1 compression. I have been street tuning this vehichle for quiet some time (turned into hobby) and still experimenting with timing in the lower rpm areas. Seems like the more timing I throw into it the better it responds.
My timing while in boost is about as good as I can get (seat of pants) without KR and have both summer and winter considerations built in. I know the timing in off boost areas seems very high compared to many files I have seen on this forum.
Can someone please take a look?
Thread Starter
Teching In
Joined: Jun 2007
Posts: 48
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From: Irving, Texas
My FI motor now has less compression than stock, more cam
(greater overlap which further decreases compression I think) different heads, etc. than a stock motor. Why would I assume the timing would remain stock in these areas?
Should these modifications alone require more timing in the off boost areas?
I have found where others also said they retained factory timing settings in there non boost areas. I just assumed in those cases they had stock blocks, compression, cams etc. which is more understandable to me. I know the only way to know for sure is by placing truck on the rollers but thought I may find some general recommendations or knowledge of timing in non boost areas. Again, this a daily driver so I'm more concerned about the part throttle acceleration and response.
(greater overlap which further decreases compression I think) different heads, etc. than a stock motor. Why would I assume the timing would remain stock in these areas?
Should these modifications alone require more timing in the off boost areas?
I have found where others also said they retained factory timing settings in there non boost areas. I just assumed in those cases they had stock blocks, compression, cams etc. which is more understandable to me. I know the only way to know for sure is by placing truck on the rollers but thought I may find some general recommendations or knowledge of timing in non boost areas. Again, this a daily driver so I'm more concerned about the part throttle acceleration and response.
You shouldn't add much (if any) timing over stock for low compression, but you might add some for the non-stock heads. I would check around and see what people were running with these heads NA. You can play around with adding 2-3 degrees over stock anywhere you want, but earlier timing cannot make up for the effects of compression. Watch for KR. Too much timing is bad for you as the early part of the burn starts resisting the upward motion of the piston if you you go too far, and it will quickly reduce torque even if you don't ping.
Jim
Jim
Last edited by DeltaT; Jul 29, 2009 at 01:18 PM. Reason: clarification
unless your running a locked out ign., most engines will respond better to more timing out of boost-that is why they make timing retards, mad sensors, etc-what is more critical is the timing under boost, its got to drop somehow,
you have to read the plugs to see where the timing is-i think under boost, i am right about the curve on the ground strap on the plug, 22 degs total
i think i start out around 30, then taper down, using a 2 bar mad sensor, but i run a carb w/msd6010, so i could program it for rpm timing control
you have to read the plugs to see where the timing is-i think under boost, i am right about the curve on the ground strap on the plug, 22 degs total
i think i start out around 30, then taper down, using a 2 bar mad sensor, but i run a carb w/msd6010, so i could program it for rpm timing control
You could spend hours upon hours playing with the part throttle portion of the timing tables. The only time that I modify the stock tables in the part throttle region is when I encounter a driveability problem such as a bucking/surging condition or a flat spot when transitioning from part to full throttle. My objective when tuning is to get the driveability as close to stock on part throttle and a good smooth transition into WOT.
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Thread Starter
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From: Irving, Texas
moehorsepower
Did you take a look at my .hpt file in the first post?
Do you think the spark advance>High Octane values below 0.84 g/cyl cells look exceptionaly high. Seat of the pants drivability feels good & with no KR.
When I compare my file to many that I have found on the forum, although none with the exact setup, my tune reveals much higher timing in comparitive cells.
How will I know when I have gone to far with the advance in these areas?
Did you take a look at my .hpt file in the first post?
Do you think the spark advance>High Octane values below 0.84 g/cyl cells look exceptionaly high. Seat of the pants drivability feels good & with no KR.
When I compare my file to many that I have found on the forum, although none with the exact setup, my tune reveals much higher timing in comparitive cells.
How will I know when I have gone to far with the advance in these areas?
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Did you take a look at my .hpt file in the first post?
Do you think the spark advance>High Octane values below 0.84 g/cyl cells look exceptionaly high. Seat of the pants drivability feels good & with no KR.
When I compare my file to many that I have found on the forum, although none with the exact setup, my tune reveals much higher timing in comparitive cells.
How will I know when I have gone to far with the advance in these areas?
Did you take a look at my .hpt file in the first post?
Do you think the spark advance>High Octane values below 0.84 g/cyl cells look exceptionaly high. Seat of the pants drivability feels good & with no KR.
When I compare my file to many that I have found on the forum, although none with the exact setup, my tune reveals much higher timing in comparitive cells.
How will I know when I have gone to far with the advance in these areas?
Thats alot of timing ! I have been thinking along the same lines with mine,low comp 402 with twins and think I am going to experiment a little as well.Dont know as I will go quite that far but we will see.As a side note,I like the smooth transitions in your timing table,I found that made a huge difference in drivability in mine.
. 
Also was asking similar question and notice the 99 cars are very agressive stock timing map in the 80 to 120kpa regions compared to say the 2002 cars in the same region. Now on NA factory cars not sure what difference it makes.
I think I can run more timing being 9.5 to 1 and being a 408 versus a 346 timing map.
But am mostly wondering in that 80kpa to 120 region should I be using a ramping up type curve like the 2002 car or a more agressive timing curve like a 99 car up till boost starts coming in with a step ramp down needed with the 99 curve and no steep rampdown needed with the 2002 type curve if you just go gradually up like 8,10,10 , 11,12 type of thing versus like 15,18, 23, 11,11 type of thing.
I think I can run more timing being 9.5 to 1 and being a 408 versus a 346 timing map.
But am mostly wondering in that 80kpa to 120 region should I be using a ramping up type curve like the 2002 car or a more agressive timing curve like a 99 car up till boost starts coming in with a step ramp down needed with the 99 curve and no steep rampdown needed with the 2002 type curve if you just go gradually up like 8,10,10 , 11,12 type of thing versus like 15,18, 23, 11,11 type of thing.
Thread Starter
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Joined: Jun 2007
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From: Irving, Texas
MY99TAWS6
I can comment on my application only as I have not tuned others.
As you can tell by looking at my .hpt file posted that I do use a ramping or transition from lower cylinder airmass (g/cyl) cells to upper. Although I accelerated the ramping effect at transition into boost. This is probably dependent on type of FI used and how quickly boost builds.
This seems to produce positive results in my case, but begining to get much harder to realize.
I was hoping that guy's with tuning experience would chime in and share a "little" knowledge on the effects of low compression and timing in the Off Boost areras of the map. I can't detect any audible sounds of detenation nor see KR on my logs. I do hear people talk about loosing torque with too much timing.
Without use of a dyno is there any rule of thumb that may be applied?
I can comment on my application only as I have not tuned others.
As you can tell by looking at my .hpt file posted that I do use a ramping or transition from lower cylinder airmass (g/cyl) cells to upper. Although I accelerated the ramping effect at transition into boost. This is probably dependent on type of FI used and how quickly boost builds.
This seems to produce positive results in my case, but begining to get much harder to realize.
I was hoping that guy's with tuning experience would chime in and share a "little" knowledge on the effects of low compression and timing in the Off Boost areras of the map. I can't detect any audible sounds of detenation nor see KR on my logs. I do hear people talk about loosing torque with too much timing.
Without use of a dyno is there any rule of thumb that may be applied?
MY99TAWS6
I can comment on my application only as I have not tuned others.
As you can tell by looking at my .hpt file posted that I do use a ramping or transition from lower cylinder airmass (g/cyl) cells to upper. Although I accelerated the ramping effect at transition into boost. This is probably dependent on type of FI used and how quickly boost builds.
This seems to produce positive results in my case, but begining to get much harder to realize.
I was hoping that guy's with tuning experience would chime in and share a "little" knowledge on the effects of low compression and timing in the Off Boost areras of the map. I can't detect any audible sounds of detenation nor see KR on my logs. I do hear people talk about loosing torque with too much timing.
Without use of a dyno is there any rule of thumb that may be applied?
I can comment on my application only as I have not tuned others.
As you can tell by looking at my .hpt file posted that I do use a ramping or transition from lower cylinder airmass (g/cyl) cells to upper. Although I accelerated the ramping effect at transition into boost. This is probably dependent on type of FI used and how quickly boost builds.
This seems to produce positive results in my case, but begining to get much harder to realize.
I was hoping that guy's with tuning experience would chime in and share a "little" knowledge on the effects of low compression and timing in the Off Boost areras of the map. I can't detect any audible sounds of detenation nor see KR on my logs. I do hear people talk about loosing torque with too much timing.
Without use of a dyno is there any rule of thumb that may be applied?
As for rule of thumb, you can take it up till you see knock and turn down or you can turn it up till you hear knock or you can be a chicken **** like me and run it way low.
Seeing those values in your tune, I highly doubt that you hit all those cells while logging (in order to verify knock retard) unless you unhooked the charge pipe. Makes a pretty 3D graph though. In the non boosted areas I run either stock timing or more depending on mods then start to ramp down in the boosted zone. Again data log and see where boost starts to come in the upper levels. If you are running low compression even at low boost you do not need to start pulling timing yet. Check your map and (depending on mods, Pistons, cam ect) start pulling timing maybe from app 3-4lbs then ramp down, Probably from around .6 Gms/cy on should be max timing pulled...
