Does 21-24" of vacum seem right at idle?
Does 21-24" of vacum seem right at idle? 11-1 347ci, Trex Cam, ported heads, Super vic single plain with 4150 to dominator adapter and a dominator TB. At idle it's between 21-24" from 950-1100rpm.. Solid 14.5-15.0 AFR in gear.
no. seems way high. thats what a completly stock engine should pull at idle. is that in gear or out? and if its out, whats the AFR?
increasing AFR to about 13.5-14.0 at idle will improve vacuume and response.
increasing AFR to about 13.5-14.0 at idle will improve vacuume and response.
The log I'm looking at right now in HP tuners shows 71 (1228rpm) to 78kpa (976rpm) at idle in gear in the 14.5-15 afr, which equates to 21.97-23.03" when i use the unit converter in HP tuners.
Couple things though, not sure if this makes a difference or not but:
There is no hole in the throttle body blades like on a factory TB. Being a dominator TB, there is an air adjustment screw to crack the blades slightly which doesn't even get in to TPS% being over 0% at idle. I have the IAC motor block off completely. I'd say the hole I had in the factory TB with LS6 intake was huge compared to what i have now, plus, I used to use the IAC motor on the LS6 factory TB tune.
There is nothing using vacum on this motor. No brake booster.
Anything wrong with that much vacum?
Couple things though, not sure if this makes a difference or not but:
There is no hole in the throttle body blades like on a factory TB. Being a dominator TB, there is an air adjustment screw to crack the blades slightly which doesn't even get in to TPS% being over 0% at idle. I have the IAC motor block off completely. I'd say the hole I had in the factory TB with LS6 intake was huge compared to what i have now, plus, I used to use the IAC motor on the LS6 factory TB tune.
There is nothing using vacum on this motor. No brake booster.
Anything wrong with that much vacum?
Edelbrock 1 3/4 stepped to 1 7/8 headers with high velocity merge collectors. Dual electric cut outs. Necks down to 2.5" and goes through a set of turbo mufflers.
Looking at an old log, had the same vacum with the same headers but 3" X-pipe with warlock mufflers.
Tune did change a bit as far as fuel concerns between the two exhausts.. I'm sure the new set up has a lot more back pressure when corked.
Looking at an old log, had the same vacum with the same headers but 3" X-pipe with warlock mufflers.
Tune did change a bit as far as fuel concerns between the two exhausts.. I'm sure the new set up has a lot more back pressure when corked.
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So your MAP reading at idle is 71-78kpa? in that case you hardly have any vaccum at idle. A stock car is in the 30 range so you have less than half of what a stock car would have. Looks like your in the 8" range of vaccum at idle. You are doing your math backwards. Remember atmosphere is ~100kpa to your stock 1bar map