I've been searching a lot on this with no definitive answers. Without my vortech there was no point in spinning that high because the engine would lose power FAST...but with my vortech the power levels off at about 7K with no signs of dropping much which will make for a better powerband if I spin it higher.

Here is my dyno:


My stock rev limit is 6,600. I have it set to 7300 right now and think maybe 7500 should still be good at making decent power.

So who's done it and who's broken it?

 

With Vortec, its going to depend more on what pulley you are running.

You don't want to spin the vortec too fast either.

Tom

 

at 7500 rpm.. you are over spinning the blower my friend.

 

Stock block and FI power should stay at stock redline IMO, even if you have the option of making more power IMO.

I believe this had a large part of grenading my stock block at safe power levels in only 3000 miles. But the decision, risk, reward and consequences are yours.

 

Even on a 3.12" pulley? I have to start doing the math I guess, I didn't think I could overspin it so easily.

I don't see why there should be a problem if you have it well tuned up to those revs. Question, what exactly failed on yours?

 

Why? Because your blower, your rod bolts, and valvetrain weren't designed to spin that fast.

 

I wouldn't touch the rev limit on a stock block/valvetrain, especially with boost. You are already increasing the stress on the engine components by adding boost...why increase it more by spinning it faster with minimal benefit?

 

Depending on the year of the car the oil pump also might not be designed to rev that high, engineering safety factor inclusive.

 

its been a while since i saw the numbers, but I believe you start to over spin the blower just before 7k rpm with the 3.12 pulley (assuming a 3.6 gear ratio, 53k max blower speed, and 32/28).

you can calc your impeller speed here: http://www.vortechsuperchargers.com/...d%20Calculator

 

So whats a safe limit to shift on a boosted 06 rev-up model? 6.6 or 6k?

 

One other thing to consider is connecting rods. Not sure of what engine set up your using but if its a stock DE engine you will most likely throw a connecting rod. Another issue is abiatic efficiency along with impeller speed.

Connecting rod stress goes up hyperbolically not linearly.

Unless you improved the intake and exhaust flow through engine beyond using a Vortech it won't make much more power in the upper RPM range.

 

1. not safe for your DE valvetrain
2. you will likely be overspinning your Vortech

 

Correct. See attached pic of NA at 7500RPM.

 

if the car is not meant or built to rev that high, dont over rev it.. simple as that.

 

when i had my utec i had the limit at 7250 and shifted at 7.
built bottom end but stock valvetrain.

ross

 

Hmmm... lots of "just because" but very little proof that there really IS an issue with revving it that high. A lot of people saying that my engine wasn't designed to spin that fast, but it also wasn't designed to do ANYTHING other than what it does stock...that's just another way of saying "just because".

I'm NOT saying you guys are WRONG, but does anyone have more info than just saying "it wasn't made to do that"? The problem is that shifting at 7200rpm ( like I'm doing now ) makes my car stay alive between shifts while shifting at 6,600rpm makes the car kinda bog after the shift and them start pulling again. Remember, my car is 5AT so the gears aren't as closely spaced as the 6MT cars.

Scotts300: From the pic it looks like you broke the ring land on the piston. I have yet to see this happen due to over revving but I HAVE seen it happen a lot due to knock. Are you sure overrevving was the problem?

 

With 8psi I move rev limit to 7200 and shift ~7000 at the track. When not at the track I pull it down to 6600. (UTEC)

At the track it helps - alot. On the street, why risk it?

About half dozen track days and 10k boosted, no issues at all yet.

 

no..bad idea /thread

 

or do it and run it hard for many miles so i can see how it works out

 

Just do it, who cares what we think if your just going to fight us about it. If he ****s up his motor its on him not us. Then we get to laugh at his thread telling us how he ****ed up his motor.