Author Topic: Reducing boost - reduce fuel?  (Read 437 times)

Offline Dunc the Funk

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Reducing boost - reduce fuel?
« on: August 26, 2021, 11:40:42 AM »
Currently we run our blower just 3% over, 33 teeth on the crank & 32 on the blower. This gives us about 15psi of boost. I want to reduce the power for a newbie driver (me) and I have a 26 tooth pulley. If I put that on the crank & the 33 on the blower that's 20% underdriven. I will also put the timing to 30 or even 28 degrees & add more wing angle. Should I take a guess at taking some fuel out of it or leave the tune alone then lean it if I have to?

Offline wideopen231

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Re: Reducing boost - reduce fuel?
« Reply #1 on: August 26, 2021, 03:59:36 PM »
3% equals .010 in fuel was rule of thumb Gorr told me and never seemed to fail me.
Relecting obama is like shooting right foot because it did not hurt enough when you shot left foot

Offline Paul New

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Re: Reducing boost - reduce fuel?
« Reply #2 on: August 27, 2021, 07:06:27 AM »
I have taken a ton of HP from my car just by changing the timing from 30 to 24

Offline Dunc the Funk

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  • Your Best Time: 7.50 @ 178 mph 1/4 mile
  • Your Engine: Big block Chevy, 517ci, 8/71 blower, methanol
  • Your Track: Santa Pod, UK
  • Your Vehicle: 23 T altered "Thundergod"
  • General Location: Yorkshire, England
Re: Reducing boost - reduce fuel?
« Reply #3 on: September 12, 2021, 06:32:38 AM »
Belated thanks for responses, I'm getting round to tweaking it today ready for next week. I've paid my RWYB entry so I'm committed now!

The '7.5' tune I have now calculates to total jet area = 0.0242in2 & the bypass is 0.0177in2 (150 pill). This is burning the plug ground strap plating but no more.

Looking at those figures I don't understand the .010 per 3%?

Offline wideopen231

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Re: Reducing boost - reduce fuel?
« Reply #4 on: September 12, 2021, 07:15:03 AM »
 3% on blower od was same as changing main .010. More blower was same as changine main to bigger jet by .010. Now this was on a 13 gpm to motor system running 14-71 at 5- to 60% OD.
Relecting obama is like shooting right foot because it did not hurt enough when you shot left foot