Roush 427r only made 400whp :(

[Ace23]

Originally Posted by LnL

I'm late to the party on this thread, but wanted to chime in.

Has the timing been verified and tested on the dyno? I have a DynoJet, and have tuned several Cobras. One guy had a Keith Craft, and swore it was installed just as it was delivered from K.C.

First pass read 408hp at the wheels. I checked the timing, and his initial was at 33BTDC! I kept reducing the timing, and the power kept going up. Finally, at 11.5 degrees initial, power was up to 439. Tweaked the jetting a little, and got it to 442rwhp.

Main Point: SOMEWHERE his distributor got tweaked, and nobody caught it before I worked on it.

As for oil capacity, just because you have a "7 quart" pan, that doesn't mean you NEED 7qt.s in the pan. As has been stated, too much oil WILL cost you HP. Having oil coolers and remote oil filters makes it harder to read the dipstick - reading immediately after shutting off a running motor can show a different level than the reading after letting the motor sit overnight. A dyno is a good place to test for optimum oil fill quantity. Start off with two or three quarts less than you "think" you need, and make a dyno pass - if you see the oil pressure fluctuate, then stop immediately and add a quart. Add a half quart, and make another pass. Repeat until you see the power drop.

Just got the car back from the body shop on Friday so I have not really driven it much. The two times I have driven it since it was tuned it has run great. The idle is at about 900rpm and I would like to raise it to about 1000.....just kinda sounds like it needs a bit more idle in it. I drained all the oil out of the car and dumped 7.5 quarts in it and marked the stick and said to heck with it. I will atleast now have a mark on the stick to now go by. When Wayne Presley tuned it he set the timing.....I would have to go back and look at what it was set at but he got to a point where he added timing and made a pull and it lost power and then he backed down on the timing. Honestly I do not know what to think.....the car has a single plane victor jr, 2.5 exhaust pipes and the headers are 2" which I've been told are way too big and hurting the bottom end. The car likes to run above 2000rpm and doesn't really sound like it gets up on the cam until about 2500rpm. It put down unimpressive power on the mustang dyno but it blows the tires off on the street and runs like a banshee if you open it up. Guessing the compression test we did that yielded 150-160lb per cylinder is where the power loss is......then again you have people that say the cam can cause lower cylinder pressure and the testers aren't accurate ect. I spoke to Keith Craft and they said it shoud be around 175-180lb per cylinder. The tuner expected it to make around 415rwhp with a 30% drive train loss on his dyno and it was about 45hp off from his expectations. if you start running the numbers its pretty simple to conclude that the cylinder pressure tells the story. The car has 12k miles on it and this was the original motor installed in 2004. The original owner was pretty old and I personally knew the last owner. The car has never been tracked or really driven hard from what I've been told and can tell so no telling where that beloved cylinder pressure went. I'm glad to have it back and looking forward to enjoying it. It has plenty of power and I'm only 3 hours and about $3,000 away from taking it back to Keith to have it completely torn down and freshened up and or changed if I ever feel the need.