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Well I got my car to the track today . It was the first track trip for the entire build . Everything went well I made a couple aborted runs as it was lean like 14.0 so I worked on getting it to a good high 11 afr but what I can’t figure out is while running a 9 psi green spring in my precision 46 mm gates it makes a nice steady 15.2 psi ???
new best for me . First 8 second pass and 4th pass on the car . Love it .
Sweet! Congrats!
This is a 392” engine with two turbos and one gate? I suppose the gate could be a bit small?
At any rate, fast for 15lbs. Those big inch deals with good heads etc sure put the small engines in their place.
Thanks Ron . No it has two 46mm precision gates but the location might be an issue . Going to work on that . Seems strong for the boost . I got off my game and made a couple short runs that were too lean but once I cought it I got it figured out pretty fast . It seems perfectly fine but I made a couple 5 second runs at high 13 to 14 afr gas scale .
Thankfully it’s on e85 and about 15 degrees timing and the iat is under 130 degrees
it’s a 4” bore 3.9 stroke. 392” engine with ls3 port 280 cc dart heads . I think with more fuel and a degree or two timing it will go 8.60 on 15 psi and I’m very happy with that.
Gate placement looks pretty good to me. I see you have lines going to the dome on the gate, do you have boost reference lines going to the bottom of the gates? Make sure there is no pressure going to the domes, make sure the boost solenoid isn't backwards. The side that goes to the dome should be vented through the center port without any duty cycle.
If you want less boost put smaller springs in and see what it does. I always go with the lightest spring available and add dome psi to go up. I use on board air with dual solenoids tho. I've seen some really efficient setups where the spring # ratings just won't match up, but not usually off more than 2-3 psi
Yes I have boost reference to the bottom then a t to the selinoid and then to top of gate. I unhooked the top lines and it still works the same . I’m thinking I might need to move the gates but will try a lighter spring first .
Congrats on the pass! What turbos are those? I think the gate placement should be more than adequate to control boost. It's certainly better than my plan on my twins.
Yes I have boost reference to the bottom then a t to the selinoid and then to top of gate. I unhooked the top lines and it still works the same . I’m thinking I might need to move the gates but will try a lighter spring first .
Yeah for sure try a lighter spring, don't worry about what the spring is supposed to be as much as what it ends up doing. 10 different cars using the same gates with same springs will have 10 different boost levels. There's alot more variables than what they say the spring should do. From the pics the gate placement looks fine to me. I've seen alot worse work ok lol
Edit- I would also check and make sure the reference to the bottom has no leaks. Like I said earlier about the boost solenoid being backwards, if you have the reference line going to the vented side of the solenoid it will make the reference psi lower in turn raising boost.
Setups with really low back pressure will be super sensitive. The supplied springs rated at “9psi” are just a basic guideline and actual boost made will be setup dependent. As long as your boost doesn’t creep with RPM, I think your gates and location are fine. Likely just need a smaller spring if you want less boost on the gate. You'd be surprised how sensitive they are. As a test, might take your dump tubes off the gates. Bet boost drops quite a bit.
I have 5lbs springs in mine and it makes 8 and creeps to 9ish by 7500. (5.3 twin 78/75’s.) I only have 38mm gates, but I do have them on the elbow.
My old 6.0 with s366's made 11-12lbs of boost with 7lbs springs & 45mm gates. My gate placement was horrible also. Current 6.0 with s369's makes 18lbs boost on 14lbs springs, 40mm gates with really
good placement.
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Boost seems to high 
