What Makes the #7 Piston Weak?
What Makes the #7 Piston Weak? Seems like that the first thing to go on a power adder car. Does it go lean for some reason? Has anyone tried running a bigger injector for that cylinder?
Originally Posted by dug
Seems like that the first thing to go on a power adder car. Does it go lean for some reason? Has anyone tried running a bigger injector for that cylinder?
TECH Fanatic
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From: Las Cruces, NM
Originally Posted by dug
Seems like that the first thing to go on a power adder car. Does it go lean for some reason? Has anyone tried running a bigger injector for that cylinder?
I run my two largest injectors in #7 and #8. Pretty common for the FI guys to do that.
Gary
Launching!
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From: Texas, dont mess with us!
Ya i heard it was mainly on forced induction cars. When you think about it, those cylinders are the furthest back and the TB is on the opposite side, seems to make some sense that they dont receive as much air... Im running a 90/90 with a direct port kit, so it should be fine. Only gives me a good reason to rebuild, should it blow. 
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Staging Lane
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Originally Posted by v8-7
Ya i heard it was mainly on forced induction cars. When you think about it, those cylinders are the furthest back and the TB is on the opposite side, seems to make some sense that they dont receive as much air... Im running a 90/90 with a direct port kit, so it should be fine. Only gives me a good reason to rebuild, should it blow.
Well the fact that the stock fuel rails do not give equal amounts of fuel to both sides the drivers side is always leaner and you can't adj each bank. The fact that the number 7 cylider is one of the farthest away would almost always make it one of the leanest cylinders with the stock fuel rails etc... How many have herd of this happening with after market fuel rails? I talked to a lot of the Ford guys at the track and that was there fix fuel rails hm. Just throwing out a few more details for you guys to think about and ponder LOL! Oh when I went lean 1,3,5,7 were all lost number 6 being the worst, but all the ring glands were destroyed. I am FI and I am still running those stock rails LOL! See you guys later.
Jeff
Jeff
Well, the fuel rail issue is correct. The farthest cylinders will get slightly less fuel. But, I think the intake design has the most effect on running lean, especially #7 and #8. If you were to think about blowing air into the intake where will it go? Of course it will be sucked into the cylinders, but not quite all of it. When that remaining air reaches the end of the intake manifold, it has to go somewhere. It will go into cylinders 7 and 8 (I think due to the intake shape cylinder 7 is most at risk for running lean). This is one of the many reasons the factory will tune the car extra rich.