supercharger and spark knock

gpp said:

let me see if i have this kinda straight.on a sc motor spark knock is the main killer of motors.next would be a lean fuel mixture.so,if you retard timing enough to prevent spark knock and make sure you have plenty of fuel you stand a good chance of running a motor up to about 480 rear wheel hp without breaking a rod or piston.i know there is no guarantee on this what so ever,but if you run a very safe tune your chances are better than running one as close to the edge to get that last hp.i really love the so call mid throttle response after raising my boost from 9 to 14 lbs but dont want to risk breakage.if i give up a little top end hp thats no problem.so,does my theory sound logical or am i crazy and need to build a stronger short block.

Click to expand...

All signs point to stroker short block. Many of the higher end speed shops recommend the improved lower end when taking the 3 valve 4.6L above the 10-12 psi mark (based on intercooled twin screw SC), or 450 lb.ft Torque (RW) according to my North Webster, Indiana sources.

$3300 gets you a very nicely designed 5.0 Stroker short block with all forged internals from these same folks. They have always done me right.

Keep in mind that the 3 valve lower end was not built with the same thought process as the 03-04 4V 4.6L Cobra Terminator engines which had a lot beefier lower end and could handle a heck of a lot more HP and Torque.

I am running 7psi on a Saleen Twin Screw and stock engine currently and will be updating fuel (volume) delivery (already have 39# injectors), cams and LT's this spring but have no further plans at this time to go the next stage (8-10 psi) until I get the money together to go with a stroker block. This will likely put me just under the 450 Torque limit (currently 407-409 T). I may even hold off on one or the other to play it safe. Nothing like a car sitting in the garage broken that you are still making payments on.

Have a Merry Christmas.

gpp said:

mine is a saleen also with kooks long tube sand converters and its at 445 on a very safe tune but pulled 460 on a better tune but risky with the stock bottom end.probably going ahead with a bottom end rebuild or just leave it alone.

Click to expand...

I was contemplating the Kooks LT's and X-tube with converters as well. Then found that Kooks LT's and the Pypes brand sitting side by side look IDENTICAL for half the price. I mean IDENTICAL. Not one bend or weld or flange different between them. So I am still in turmoil on which way to go. I like the thought of having a cammy sound with the Detroit Rockers that Brenspeed now has available, but I also like the sound of the LT's with the high flow cats as well. Guess I will toss a coin come spring time.

gpp said:

i assume they are stainless steel and the flange is the same thickness.if so go for the pypes.

Click to expand...

Oh yes.