Max rev limiter with 272 cam

[syn52k]

I am looking to spin my motor a little higher. I have a m20b25 that i currently spin to 6800K at 17 PSI with mega squirt on a stock cam. I had recently sourced a brand new IE 272 cam that i am going to put in along with hd rocker arms from IE, but thought about upgrading the springs while i am in there.
Anyone have any recommendations or thoughts on stock valves with a 272 with forced induction? what is the highest i can spin with that setup? Should i upgrade my springs and if i do with a 272 what is the highest i can spin at? not sure if it matters much but i have a 3.73 rear.
Thanks!

[AWDBOB]

I am looking to spin my motor a little higher. I have a m20b25 that i currently spin to 6800K at 17 PSI with mega squirt on a stock cam. I had recently sourced a brand new IE 272 cam that i am going to put in along with hd rocker arms from IE, but thought about upgrading the springs while i am in there.
Anyone have any recommendations or thoughts on stock valves with a 272 with forced induction? what is the highest i can spin with that setup? Should i upgrade my springs and if i do with a 272 what is the highest i can spin at? not sure if it matters much but i have a 3.73 rear.
Thanks!

The question shouldn’t be “how high you can spin” but “how high you’ll make efficient power”, especially with a turbo.

The 272 will move the curve to the right a bit, but you were already likely pumping a lot of hot air at 6800 before on the stock cam.

What does your boost plot look like on your current setup?

I would put the new cam in, and look to see where you are making up for inefficiency with boost and stop a bit before there, which if I had to take a stab at it would be around 6800.

[TobyB]

The only limit's going to be intake valve float, especially with forced induction.

So yes, use stiffer springs. You're fighting inertia AND pressure, so generic numbers would be
'stock plus 30%' to give you a little margin of safety.

That said, the little I know about forced induction cams is that you don't want a lot of overlap,
as you'll just blow your wad right through the cylinder unburnt.

Likewise, with the stock intake, it's going to be working against flow up that high,
so you'll see Bob's inefficiency really rise up against you when you hit the manifold limit.
(which we all think is in the 6800 rpm range, but with boost, who knows?)

t

[McGyver]

Likewise, with the stock intake, it's going to be working against flow up that high,
so you'll see Bob's inefficiency really rise up against you when you hit the manifold limit.
(which we all think is in the 6800 rpm range, but with boost, who knows?)

With boost, you're mechanically forcing air into the engine. So yeah, the manifold may be a restriction, but the turbo should easily overcome it. Then again, at what airflow does the turbo become inefficient and start adding too much heat to the charge air?

Realistically, the rpm limit should be based on where OP is making the most efficient power, like bob said.