Retarding timming underboost
10-08-2004, 10:03 AM
#1
1.5 BAR
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Join Date: Aug 2003
Posts: 1,341
Retarding timming underboost
I was chatting with a couple guys I know at some races this weekend. These guys build 10 second Honda's and have amazing setups. They tune with huge injectors and AEM EMS.
I was telling him that I retarded my ignition around 0.8 degrees per pound of boost. He was saying it was way too much and the rule is usually 2~2.5 degrees per 5 pounds of boost. So, 10psi, no more than ~5 degree retarded timming. So, around 8.5psi (which is what i'm running), my ignition would be retarded ~6.8 degrees.
He was telling me that if I advaced my ignition, using that general rule of thumb, I should make way more power than I am now, and I shouldn't have any problems because of the rich fuel mixture i'm running.
So my question is, is he right?
Stan
I was telling him that I retarded my ignition around 0.8 degrees per pound of boost. He was saying it was way too much and the rule is usually 2~2.5 degrees per 5 pounds of boost. So, 10psi, no more than ~5 degree retarded timming. So, around 8.5psi (which is what i'm running), my ignition would be retarded ~6.8 degrees.
He was telling me that if I advaced my ignition, using that general rule of thumb, I should make way more power than I am now, and I shouldn't have any problems because of the rich fuel mixture i'm running.
So my question is, is he right?
Stan
10-09-2004, 02:26 AM
#3
1.5 BAR
Join Date: Mar 2003
Posts: 1,190
Re:Retarding timming underboost
bullshit; the UD forums move slow as ---- and you'd get your question answered 10x faster on here. not saying the answer would be correct however... anyways. detonation can still occur with 12.0 afrs if you don't retard your timing enough. I retarded mine 0.7 degrees per lb. of boost and if you want to see what happened to my rods just check my avatar... but I was at 13psi... you could say that my rods were just not strong enough, but i'm sure d15 rods are okay up till at least 180 hp, and I know I wasn't making that much power.
10-10-2004, 02:32 AM
#4
1.5 BAR
Join Date: Jun 2003
Posts: 824
Re:Retarding timming underboost
It all depends. With a properly designed combustion chamber you can run less timing, and make the same power. To much timing can cause a "negative torque" effect. Or the mixture expansion working against the regular rotation of the crank.
10-12-2004, 06:25 AM
#5
3.0 BAR
Join Date: Apr 2003
Posts: 11,058
Re:Retarding timming underboost
Originally Posted by Will
bullshit; the UD forums move slow as ---- and you'd get your question answered 10x faster on here. not saying the answer would be correct however... anyways. detonation can still occur with 12.0 afrs if you don't retard your timing enough. I retarded mine 0.7 degrees per lb. of boost and if you want to see what happened to my rods just check my avatar... but I was at 13psi... you could say that my rods were just not strong enough, but i'm sure d15 rods are okay up till at least 180 hp, and I know I wasn't making that much power.
and like i stated, a step retard is more effecient and if you knew anything about his set up, he has a low comp. b18, so he could more timing
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