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?

 

It is the design of the intake.

 

You must be thinking of the 4.6 Cobra motor that has the problem of frying the #7 when it is taken to top speed for more than a few seconds. There was a long thread about it on the Corral.

 

We have similar problems on #7 and #8.
Also they seem to spin rod bearings there more than other Cyl.

 

Interesting. I am gonna have to check out the corral. Maybe its a common problem among v8's

 

I run my two largest injectors in #7 and #8. Pretty common for the FI guys to do that.

Gary

 

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.

 

When I was spraying, I blew the ring lands off of #7 only....

 

Me too, I cracked the block also

 

Local dude here (juiced setup) just busted his #7 dual spring.

 

What is the firing order ?

 

1-8-7-2-6-5-4-3

 

maybe if we swap #7 piston with #1 piston it will be all good.

 

could u post a link to that coral write up?

 

Actually they recieve MORE air. They run lean because air entering those cylinders has a straighter shot into the head. All the front cylinders, the air has to make a very hard 90 deg turn right after going through the throttlebody.

 

You only run into that with the front mount tb. It would not be a problem if you run a carb style intake.

 

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

 

something else to take into account is the back 2 run rich on a dry shot, and lean on a wet shot.

 

There is a solution:

ITBs, one TB for every cylinder. Aussies have a good grasp of that, but setups are still expensive.

 

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.