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Adding timing to a turbo sled!! Good idea it bad

F
Nov 27, 2007
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medicine hat
I am trying to find some better response with Impulse kit off the start at idle, once up in rpms, response is fine

Has anyone played with timing, seen that timing is at -.05 degrees, for the hell of it I tuned it up a degree and took it out in the low elevation test in the feild, sled felt much more responsive seat of the pants and even a different sound at idle, like a more rank sound..

Anyone else done this.. good or bad idea, I always run 100 percent av gas and 7-9kbs boost at 6-8000’

Thanks for the reply thanks
 
F
Nov 27, 2007
2,495
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medicine hat
Talking with bj and Linderman last night both felt one degree increase should not be much a problem, as long as good fuel is being used.. Timing key would be real sweet
 
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inspector01

Well-known member
Mar 21, 2013
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Proper way would be to adjust timing curves only where necessary, timing keys are a bandaid.
 
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Turbo11T

Well-known member
Nov 26, 2007
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Lake Crystal, MN
From my understanding the BD key pulls timing as RPM's increase. So little effect down low where we need more timing. So If we could add a couple degrees on the bottom and the key would pull 3 degrees back at 8000 rpm that would do the trick.
 

brycter

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www.turboboys.net
You have to remember timing effects the back pressure in the pipe. adding timing will make it flow a bit better. but will also increase you cylinder pressure. it is a tight wire walk. make sure you have good fuel. and might be good to test the rvp before playing too much with your timing
 
F
Nov 27, 2007
2,495
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medicine hat
Talking with another builder he seen some pretty decent gains advancing timing at lower rpm, said if a guy droped boost a few lbs and added some pump you will quickly see the same results.. Av gas is very safe, but burns very slow and could be the cause..
 
F
Nov 27, 2007
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medicine hat
Reason I like using it over race gas is its avableabilty at the airport.. No barrels, jugs or mixing of race/pump..

Negative is with the impulse it pretty lazy from a dead stop till spool, and in trees it not very desirable, will try a degree or two of timing and see if it will be quicker for the lazy flame front av gas.. Maybe drop boost down a few lbs
 
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Turbo11T

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Nov 26, 2007
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Lake Crystal, MN
Fred, How much boost are you running on straight avgas? And what elevation. I have been running 7lbs at 8000+ with 80/20 91 to Avgas and have not experienced denotation. That being said I am not a shoot climber so no 1 minute long pulls for me.
 
F
Nov 27, 2007
2,495
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medicine hat
Been running up to ten lbs on strait av.. And that is on the dial gauge, they are not the most accurate to read.. I ordered a few digital gauges but have not used them yet, and hoping to get more accurate readings.. This has been as low as 6500' to date have had no knock detection go off at that

Have done pulls that have been over a minute long numerous times at that
 
T

Turbo11T

Well-known member
Nov 26, 2007
3,062
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Lake Crystal, MN
Been running up to ten lbs on strait av.. And that is on the dial gauge, they are not the most accurate to read.. I ordered a few digital gauges but have not used them yet, and hoping to get more accurate readings.. This has been as low as 6500' to date have had no knock detection go off at that

Have done pulls that have been over a minute long numerous times at that



10lbs is a boat load. . . You do need full av for that. Ever think about trying say 5 lbs on straight 91? Just to get the feel if the bottom end is affected by the avgas? I remember many years ago I had a set of pipes on a 800HO that I was supposedly needed race gas. So I was running that. But I had a time where I wasn't able to and man it was a totally different animal. It was way more crisp. I was surprised that it could change the characteristics that much by running to much octane. These engines obviously pre boost only have the need for 91 octane or less depending upon elevation.


I do think that the timing map preboost could really help with the bottom end. But then I am also cautious to say this because why wouldn't the turbo kit makers have this feature?


I like to question everything though so that thought still exists in my head.
 
F
Nov 27, 2007
2,495
712
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medicine hat
10lbs is a boat load. . . You do need full av for that. Ever think about trying say 5 lbs on straight 91? Just to get the feel if the bottom end is affected by the avgas? I remember many years ago I had a set of pipes on a 800HO that I was supposedly needed race gas. So I was running that. But I had a time where I wasn't able to and man it was a totally different animal. It was way more crisp. I was surprised that it could change the characteristics that much by running to much octane. These engines obviously pre boost only have the need for 91 octane or less depending upon elevation.


I do think that the timing map preboost could really help with the bottom end. But then I am also cautious to say this because why wouldn't the turbo kit makers have this feature?


I like to question everything though so that thought still exists in my head.



Talking with Redline, he feels the same about fuel and going with more pump and less Av gas, dropping boost some..

And in his findings timing has brought lazy fuel around quickly down low, recommends it..


Sent from my iPhone using Tapatalk
 
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Turbo11T

Well-known member
Nov 26, 2007
3,062
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Lake Crystal, MN
Talking with Redline, he feels the same about fuel and going with more pump and less Av gas, dropping boost some..

And in his findings timing has brought lazy fuel around quickly down low, recommends it..


Sent from my iPhone using Tapatalk



Does he have a solution to modify just that part of the timing map?
 
F
Nov 27, 2007
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medicine hat
Dave has a few ideas he wants to spend some time on to try in make this happen, for the 800 etec, still thinks if he can alter fuel off the start, the lag will disappear quick and has a few ideas to do that, once he gets his mind on something, he ussally figures it out, hope to have the Impulse sled up to him latter this month to play with
 
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Turbo11T

Well-known member
Nov 26, 2007
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Lake Crystal, MN
Dave has a few ideas he wants to spend some time on to try in make this happen, for the 800 etec, still thinks if he can alter fuel off the start, the lag will disappear quick and has a few ideas to do that, once he gets his mind on something, he ussally figures it out, hope to have the Impulse sled up to him latter this month to play with



I totally agree if we had a way to change the gulp of fuel that a stock non boosted sled needs then we would be golden. I had toyed with ideas in my head such as fooling the air intake temp to lean the sled. I am not sure it would do enough to make the difference. Of course I do not have complete knowledge of how the ecu uses each input to modify fuel and timing needs or the RAVE functions.


When and if he figures out how to pull some fuel from the bottom end I would love to have that ability on my sled.
 
F
Nov 27, 2007
2,495
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medicine hat
He threw me his idea yesterday and don't want to mention it on here, but in reality I think it could work, to reduce the fuel at bottom for a few milli seconds.. :eyebrows:

Can imangie how many he would sell if it was just a quick fix to clean up bottom end..

He also mentioned how well his new turbo design on the 850 with pump fuel is, sounds like it's even better than the Poo kit of his and I was totally blown away how quick it spooled in the spring compared to my impulse.. Can't wait to throw a leg over it
 
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Turbo11T

Well-known member
Nov 26, 2007
3,062
751
113
Lake Crystal, MN
He threw me his idea yesterday and don't want to mention it on here, but in reality I think it could work, to reduce the fuel at bottom for a few milli seconds.. :eyebrows:

Can imangie how many he would sell if it was just a quick fix to clean up bottom end..

He also mentioned how well his new turbo design on the 850 with pump fuel is, sounds like it's even better than the Poo kit of his and I was totally blown away how quick it spooled in the spring compared to my impulse.. Can't wait to throw a leg over it





PM"d you.
 

madmax

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Nov 26, 2007
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Salt lake city
Just wondering how you are adjusting timing? The impulse kit has its own ECU doesn’t it? You have to hook it up to a computer to tune?
 
F
Nov 27, 2007
2,495
712
113
medicine hat
I use candoo software and it allows me to advance or retard timing..

Had both aero and impulse sleds out yesterday in the feild.. 2400' and did some testing since adding timing..

Both set to seven lbs boost, the impulse felt like quicker spool, or less hesitation, as the aero felt similar to before..

Aero is just a much quicker spool, but there is more pin weight with impulse..

Went to a 43-47 helix on aero and it's quick out of the hole, but could suffer a bit in back shifting, play with it today
 
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