how do you go about changing the redline on a TPI 350? what factors contribute to an engines redline? is it the valvetrain, or rotating assembly? im asking because im going to be siamesing my intake soon to rev to 5500-6000 rpms but the stock redline shows 5500 rpms or so. thanks in advance

 

'Redline' is where your horsepower peak is.

But you might not be able to get there because of valve springs, lifters, etc. I'm sure other people on this board will suggest other things.

 

i thought "redline" was the threshhold of engine damage, i want to know how to raise this limit

 

$$$$$$$$$

 

Redline is right before where valve float or engine damage happens. Peak horsepower is where your horsepower peak is.

It's a whole combination of things, but good/correct valvesprings and a well-balanced rotating assembly are probably the two biggest factors. Also, lighter moving components (reciprocating assembly and valvetrain) help out because having less inertia places less strain on internals.

Also, putting aside the engines ability to handle high RPMS for a moment, being able to get that high is going to depend on your cam, heads, and intake/exhaust flow.

 

If you want to spin your engine higher first make sure your bottom end can handle the load. Then you'll need a bigger cam, with matching springs and such, and high flow intake. It also depends on how much you want to raise it. All kinds of factors affect redline. If you want to go up to 6 grand, that's no big deal, if you want to do 7500-8000, that's takes a lot more, and if you want to do more than that I hope you have a huge credit limit.

You said 5500-6000, just doing your intake will get you there, but not with the best power. You'll want to do a cam swap as well, following the manufacturers spring recommendations, and probably do a basic porting on the heads. You'll probably also want to get screw in studs for the heads while you're at it.

 

As has been mentioned in previous responses on this thread, a number of factors enter into where your "red line" is located. One thing that wasn't mentioned is that intake runner length also influences how fast you can turn the engine for peak horse power. The tuned port injection set up is "tuned" for max power @ 5000 -5500. In a 350 it is a little lower because the system is sized for a 305, and needs to be bigger for a 350. To run higher rpms, you need to shorten the runners.

 

i am siamesing my base manifold to shorten the length of the runners. i wanted to know what has to be done to raise the redline from 5500 (what it shows on my dash) to 6000. from the sounds of things, the stock bottom end should be able to handle 6000 rpms, and alls i would have to change would be the valve springs. im not intending to rev it up to 6 grand everyday, just occasionally at the track

 

I'm not sure on this, but I think siamesing the base to shorten the runner length might be doing it at the wrong end of the intake, and virtually eliminate any "tuned port effect" on the intake side. Don't you need to maintain a separate runner from the plenum all the way to the port to get any "tuning" advantage.