I have a built motor with forged internals (supertech pistons, ATI damper, M tuned rods, boundry oil pump, supertech heavy doubles, Supertech SUB's and custom cams (web cam). I have been staying under 8k for the last 10 hours, Leakdown looks great and I want to turn up the wick a bit. What's a realistic redline with the above parts?

I like to have 2 redlines. One that I normally run to and another when I need to have that extra bit of pull (at the expenses of excess wear) to get around another car. I am thinking 8k and 8,800.

 

Estimates from 949s site


Single spring - seat pressure 56lbs @ 34.2mm
Sustained revs to 8000rpm, mechanical over rev to 8600

Light double spring - seat pressure 63lbs @ 34.2mm
Sustained revs to 8400rpm, mechanical over rev to 8800

Heavy double spring - seat pressure 74lbs @ 34.2mm
Sustained revs to 9000rpm, mechanical over rev to 9300

 

pressures are dependent on cam profile, not just came specs but ramp rates. Its best to listen to what the cam manufacturer says for seat and open pressures. My integrals only required single springs to meet their requirements for 9000 rpm limit.

I never revved my engine that high though, 8200 was enough for me even thought i think it could have made power to 9k.

 

my question is: are you making power up there?

 

It will continue to make power as high as I am willing to spin it because of the Rotrex. The current dyno never noses over near redline. It just climbs with RPM.

 

forgot about your thupercharger, good point.
is this a bp4w, bp6d, or a bp05? I think you may still choke up top, but that depends on your IM and cams......

 

Power has not even nosed over at 7,700 yet. Safe to say it got good airflow up top.

 

ST heavy doubles in my setup, and we heard no float when I accidentally let it go to 10.3krpm at the Rototest (poor footwork and only ignition retard as rev limit). So the springs are hard enough, but I don't remember the installed pressure, my builder did his own thing.

My ramps are not that aggressive though, cams looks as pointy as stock, not "square".
Less duration and more ramp is starting to become an attractive test (CR is still low).

Wear comes quickly when you go up there, how many hours do you want to run between head rebuilds (springs times revs means shorter seat "life")?

 

I know wear and tear above 7,700 gets pretty bad. I want to make it a habit but want the option to go beyond that if the situation really warrants it. Based on Rotrex limits and keeping wear reasonable maybe 8,500 is a good upper end rev limit. I will still keep the shift lights at 7,700 though. If the situation warrants it I will just keep my foot in it till the rev limited 8,500.

 

With the BP6D I redline at 8500 with some sort of single supertech springs from trackspeed and stock lifters. I have a set of inside springs that go into them that I'm going to install at some point for piece of mind, probably along with SUBs. Valve train isnt too worrysome for me with reving higher. I worry about the bearings in the bottom end. Theres only so much force you can put on the rod bearing before it makes contact based on its width and oil pressure and clearance.

 

don't you have a bp6d?

also you're not worried about valve seats getting pounded with that much revs?

I know failflora revved his to kingdom come, but afaik he's the only one, and not exactly a build you'd want to imitate

 

I'm not worried about valve seats getting pounded with the revs the ramp angle on most cams is so slight during valve lift off and closing that the forces dont climb too quickly with revs. Now valve float on the other hand when running stiffer than stock springs would probably mean a quick death to the seats. If I could get lighter and longer rods and lighter pistons I would consider spinning higher, but thats for engine V2.

Even a cam shaped like a rectangle wouldnt concern me too much with our direct acting heads (no floppy *** rocker arms), but probably would require custom valve springs from a NASCAR shop and maybe boring out the oil lines to the cam journals to get a little more pressure up there if you went completely fully stupid retard more than anyone runs on anything outside of F1 cams (mild hyperbole).

 

A friend of mine used to run a BP4W to 9k on a turbo track car. I'm not sure what his valve train was, but I know that he ended up backing down the RPMs because he saw excessive bearing wear after only a few events on the motor.

 

I'd like to see what Emilio has to say on the subject since he must have gotten his 9k rating from somewhere. He would have a lot of upset customers if not i would assume.

 

The numbers on our site are the accumulation of various data points over the years and also some calcs by my engine builder. They are a tad conservative. YVFMV (Your valve float may vary).

 

I took that into consideration when I choose the heavy doubles. Cam profiles and valve train weight change the point of float. My cams have steep ramps and the +1mm valves add weight. I come down to one of the supertech doubles. I opted to be on the safer side with the heavies even if it means some added wear and tear. Far better than floating and bending a valve.

 

Is the entire rotating assembly balanced including clutch/flywheel/damper? I assume it is but I can't believe no one has asked this.