15 or 30 degree spray pattern, a difference of 40 rwhp???
Thread Starter
Teching In
Joined: Jan 2004
Posts: 10
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15 or 30 degree spray pattern, a difference of 40 rwhp??? The car is a 1998 Trans Am with the only mods being a powerdyne supercharger, QTP cutout, and bosch 42.5# injectors.The guy that is going to tune my car asked me if i had a 15 or 30 degree spray pattern, well i had no idea so i called muscle motorsports (who i bought my bosch injectors) and they said that they thought is was a 30 degree spray pattern but wasn't sure. So i call this guy back who is tunning my car and he said that i need the 15 degree spray pattern. When i asked why he said that with a 30 degree spray pattern, the back cylinders will lean out, so in order to NOT lean them out i would have to run a 11.6:1 instead of 12.3:1 air/fuel ratio, so it will run more rich. When i asked what the problem was with running a tiny more rich he said that i will lose 30-40 WHEEL HORESPOWER. This is hard to beleive can someone please help me, i would really appreciate it. Thank you
TECH Enthusiast
Joined: Aug 2003
Posts: 596
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From: Downers Grove,IL
So i call this guy back who is tunning my car and he said that i need the 15 degree spray pattern. When i asked why he said that with a 30 degree spray pattern, the back cylinders will lean out, so in order to NOT lean them out i would have to run a 11.6:1 instead of 12.3:1 air/fuel ratio, so it will run more rich.
Some guys like the 15 degree angle as it hits the valve back side better. Some like the wider spray angle better for other reasons.
And 30-40 hp loss from 11.6- to 12.3:1 AF on your combo is VERY hard to believe.
Heck I run my motor at 10.5-10.7:1 A-F.
