91 Mustang stock block build TT T3s set up log headers
GT40 iron heads ported...eddy intake ported...1.7 rockers
stock computer...on the stock cam on 91 fuel...ignish at 20*ran fine
swapped the cam for an F cam...& Ive had to drop the timing
to 18* to keep it from detonating at 12psi...suggestions? thanks

 

How does the car drive? More power? Did it push peak torque up in rpm? What turbine wheel and A/R do you have?

I wouldn't say this is abnormal but it can be fixed. What needs to be matched is the turbine/turbine housing to your cam so that the drive pressure doesn't cause exhaust to contaminate intake charge. I'm not totally familiar with the specific cams you have BUT, I'm sure the F cam has more overlap than the stock. If this is indeed the case, you can put bigger A/R turbine housings or larger turbine wheels in the car to relieve that pressure. It's only two degrees of timing so it's not a crazy amount. The big thing is does the car run better/faster? If so, I would leave it alone unless you yet again want more power.

 

thanks for replying
when I had the car out the last time it was cold...say 40*F
it was a beast...no detonation on 94 octane...best its ever run...so I know its all there
just need to get rid of the detonation...theres been .004 off the heads...but I doubt at 12 psi thats a concern on those heads
someone else sed the same...exhaust in the intake charge
he also sed to retard the cam timing about 4*...could I use a different rocker arm ratio to get the same thing?
I could run race fuel or a water/meth...what are your thoughts?

 

I'm always a fan of water/meth. You could probably even push the boost to 16-18 on it with no detonation.

I don't think the rocker ratio will do the trick. Its a good question on the cam timing itself. It won't be as good as a new cam all together but I'd have to think about that one a minute. Is it easy to change cam timing on your car?

 

no...its a stock new replacement chain & sprocket set
however I could use an offset woodruff key,,,its ol school stuff
do they even do that anymore?

 

I talked to one of my best friends, Reed Patridge at Work turbochargers. He said to advance the cam but it won't make very much difference either way and will restrict your top end quite a bit. Do you know the specs on your turbine housings and wheels? Maybe go a size up in your A/R and it will do exactly what you want.

 

well Im thinking a cam change is a lot more cost efficient than changing two turbos hot sides

 

It depends. If you have room to just change the housings, depending on what flanges you need, they are only a couple hundred dollars. It will cost slightly more for parts than a cam change but may make up for it in labor and it even out. Then you have the sound and performance you want.

 

IMHO, a good meth system would REALLY be just the ticket for your combo.

 

So the f cam doesn't appear to be a bad turbo cam 226,226 on a 114 ls so I have some questions... Is it only reversion causing the issue, or is it making more cyl pressure at peak torque? Is it tuned, or just locked out? AFR? Is it detonating just at peak torque, or throughout the rpm band? Pull a couple degrees at peak torque, and ramp some timing back up top? There seems there could be quite a few ways of fixing the issue.

 

ya I tend to agree...I dont think it wants much to find the *sweet* spot where its happy
as I sed...its run really good before the cam swap...on 91 fuel...anytime Ive had detonation
nothing ever got burned bent or broken except HGS & it ran three seasons no problem on 10-12 psi boost
its ALWAYS been edgey...you know...you could tell right away when you got a not so good tank of fuel?
Im of the opinion...it just wont run good on 91 now...

we had the car out in the fall in the colder weather...on 94 in the cold there was NO detonation
& the car was blowing the tires off in 4th rolling on the throttle (poor little T5)...so she will run

 

Short of a meth system, I think I'd be looking at ways to tune other than the stock ECM, probably one of the MS systems.

 

of course...Im just stubborn & want it to run ok on the stock computer
many have done it before me...its actually run pretty good... driveability issues ok
on a stock A9L...that was barely acceptable when it was marketed...does a little hissee fit on start up
but otherwise it runs & idles fine
ya MS is the bomb...been thinking about that for a few seasons

 

Soooo I'm not telling you anything you don't already know and just don't have quite enough ambition to go ahead and do it?

 

yep...I know one or two things...its the two or three things that messes me up..

one of these days Ill quit playing with the toy stuff & do a serious build...but for now its what it is