Strange rpm limit

[dank GN]

Okay so in park I will quickly rev it and it hits 51-5200 rpm and it starts to sound weird and doesn't climb in the rpm . If I slowly get the rpm s up it goes to 6000 and sounds clean the whole way . What would cause this? Springs? Ignition ?

 

[PSID6]

What kind of tach? If it's stock I think that's the problem, just not that accurate.

 

[Buick Mark]

Why in the hell would you want to rev it that high with no load on the engine, of course something is going to sound weird, its going to sound really weird when a rod comes thru the block

 

[we4Mateo]

^^^^^agreed. OP, stop doing that. Test it in gear and let us know if you have a problem, but either way, stop doing that.

 

[novaderrik]

Why in the hell would you want to rev it that high with no load on the engine, of course something is going to sound weird, its going to sound really weird when a rod comes thru the block

is there some some sort of different laws of physics that applies to turbo Buicks where free revving them is more harmful to them than other engine families?
i used to rev the 355 in my Nova to 7400 in neutral, and it never blew apart.. regular small blocks with good valve springs will spin past 6000, loaded or unloaded..

 

[Buick Mark]

Its not a good idea for any engine

 

[dank GN]

I was having problems with it not revving past 5k on the Dyno .

 

[dank GN]

Guys it's not like I do that all the time I know it's not great for the motor it was a test to see if it was my valve springs going out

 

[David Husek]

What valve springs are you running in this engine and at what pressures? Is the camshaft a flat tappet or roller?

 

[dank GN]

212/212 flat 980
Seat pressure right around. 90lbs @1.7

 

[we4Mateo]

Guys it's not like I do that all the time I know it's not great for the motor it was a test to see if it was my valve springs going out

They'll act differently with boost and exhaust pressure on them anyway, so free revving really doesn't indicate anything.

 

[dank GN]

I would snap the throttle open and it would not want to go past 51-5200 but if I went through the rpm rang slow it would rev to 6k clean what would cause that to happen ? Springs ? I just ordered some but now I'm thinking it's ignition issues . With load it doesn't like to go past 5200

 

[dank GN]

They'll act differently with boost and exhaust pressure on them anyway, so free revving really doesn't indicate anything.

So what would cause my problem of the motor not going past 52k?

 

[notacarlo]

Peak torque and horsepower for a stock LC2
Under load
Posted from the TurboBuick.Com mobile app

 

[dank GN]

I think stock they rev out to around 5k

 

[notacarlo]

5200

Posted from the TurboBuick.Com mobile app

 

[notacarlo]

Torque was lower, HP around 4400 but they easily spin to 5200 in 3rd making power

Posted from the TurboBuick.Com mobile app

 

[dank GN]

I have a 212/212 flat tapped cam so it should make power up to at least 58-5900

 

[hungerbuhler1]

subscribed. Having same issues.

 

[Chuck Leeper]

Guys it's not like I do that all the time I know it's not great for the motor it was a test to see if it was my valve springs going out

That "test" is not a valid method to check your valve springs....Nor, much of anything else.