I recall a year or two back where someone was shifting around 7000 rpm's on thier build block.

I know there are some cams out there for the 5.4, that make max power above 6000rpms, and are designed to turn those Rotations.

Just curious if anyone here has more information about that?

 

i wonder at what rpm JLP shifts

 

I'm not sure what's opimal for a "bolt on" / built type motor? I'd suspect a 5700-6000rpm shift point though. These things have a long stroke. Long strokes and high rpms don't go with each other.

Rich

 

I was shocked when I saw how our rods looked when I tore down my old motor.

 

All the dyno sheets I've seen peak under 6K so unless the power peak can be moved up farther there isn't much reason to spin them any faster. I've heard of 4.6's spinning up to 9600 rpms but nothing on the 5.4's.

 

Where do the stage 3 cams make power? I was under the impression (could be mistaken) that it was at the high rpms. I figured if you bumped the rpm's up a little, or alot, you could gain some more power.

 

HI!... When I built my "BUILT" 5.4 I designed it to withstand 7500RPM but I will never go that high. When I had the old CROWER cams in it I would take it to 7000RPM in 1ST gear all the time. Now with the COMP-CAMS in it I only make power to 5800RPM due to the A/F's go to crap. I need a tune. The 1ST run on the dyno I took it to 6850RPM with no problems. On the dyno 3200RPM in 3RD gear.... PUNCH IT and it only take about 4-5 seconds to reach 6850RPM and 142MPH! lol! Not bad for 4.10 gears. The COMP-CAMS I have are TURBO grinds custom ground for my application. They told me they would make power to about 5800 - 6000RPM in N/A trim with my 8.42:1 compression. With my turbo T-76 set-up they told me to expect 6800RPM +.

 

What's the redline on the 2000 Cobra-R?

 

Bill, the 2000R has aluminum rods if I recall. Much easier to rev to 7k with those. Plus they weren't meant for daily use.

I'm not a big fan of high rpm 5.4s. The long stroke puts a big side load on the piston and cylinder wall when the crank is at it's lowest point. That's a lot of stress on the upstroke at the bottom of the cylinder. I'd say 6k is the max for a good breathing 5.4. Honestly, I've never really seen many even make power that high.

 

If I remember right 5700

 

6500 RPMs. Of course, its a 4V which prolly helps it.

 

The "Big Dogs" are taking them quite high in rpm with lots of turbo boost and ported 4V heads. The problem for us is the limited port and valve area is keeping peak hp lower. The cam is only part of breathing potential. For max power the cam specs need to allow a peak rpm that is below the airflow peak of the heads. If not you give up power on the low end that you can not regain at the top end. AIr flow though my ported 2v heads is only about 70% of what my aftermarket 302-351 Windsor heads flow

The 4.6 peaks higher because with the same head, and rpm, the air velocity is much slower in the smaller 4.6 motor. The head determines maximum hp and the displacement of the motor determines at what rpm the motor will reach that peak.

As far as cam specs go, even a Stage III cam is rather mild for a race only motor. Power at high rpm would require more cam AND port flow.

 

Wow that is spinnin for our 5.4L




Though if I wanted something that could rev. I would have gotten an S2000...9000rpm redline stock...first time someone told me about them I thought it was a motorcycle

 

Nope. Carillo forged rods but not aluminum, just expensive.

 

Actually, Carillo billet rods.