What derives the lower rev limit of the 2.5 engines?
My current 2.0 (2.1stroker) is at its limit due it being an open deck block and I just want to keep an eye open for future upgrades. If I'm going to convert a block to closed deck (closed deck blocks seem quite scarce atm) I figure I might as well convert a larger capacity engine but I'm concerned about the lower rev limit.
Any thoughts?

 

When you say at the limit? What limit is that?

They run perfectly well at well over 500hp....

 

The rev limit is governed by the power band, no point revving it to 8k if power is tailing off at 6.5k. Put a GT35R on a 2.5 engine with decent heads and it will pull to almost 8k no issue

 

What would you call decent heads?

JGV: as in, mapper won't push it further than 440bhp @ 28psi

 

So you are at the Rev limit of an open deck block? That makes no sense....

Decent heads are decent heads.... flow benched, port matched, over size valves, double springs, retainers, lairy cams, etc...

 

Basically supertech valvetrain plus aftermarket cams such as 272s

 

Well either your engine spec is poor or your mapper is a wimp.

Ran mine at over 2 bar for years and 550+hp on meth

 

Agreed J, makes no sense at all

 

Pat @ Scoobyclinic.
Spec: 2.1 budget RCM stroker kit, JDM big port AVCS heads with UK spec cams and valves (bought heads from here recently), HDI FMIC, ID1000, RCM 340, fuelab FPR, GT spec headers, SC42+, Meth injection kit, 4bar map sensor, syvecs. Think that's about it. I know the turbo won't help with the power but was hoping for over 450bhp on the meth map.
Yes, I know RR figures mean very little in the real world blah blah....

 

No. Sorry, I may have been unclear. I'm at my power limit, according to my mapper, due to me having an open deck block. This is my current situation.

I started looking at CDBs, realised there aren't many about, looked into CDB conversions then looked into 2.5 CDB conversions and wondered why the rev limit was in place (which Banny answered).

As per a previous thread on here, in which you proved to very helpful and convincing, we discussed cams and torque curves etc and I agreed that midrange and a wide-as-possible torque curve was preferable. That's why I was concerned about the lower rev limit of the 2.5 engines, as I figured it would cap the upper limit of my torque curve.
Does that make sense?

EDIT

And yeah, I re-read your reply and realised I'd read your reply wrong so I edited my reply!!! FFS! lol

 

That's alright it makes sense now!!!

Personally I'd stick with the open deck block and ask for it to be pushed a bit more...... unless there is a component in your engine that can't handle it? The block will be fine...

Like I said my odb did 30k miles at over 500hp. A piston gave up when we started pushing it towards 600. But that was due to a manufacturing fault with the pistons and gudgeon pins not the block.

And bare in mind my subaru is a track and weekend toy. Everytime I go out in it I kick it's ****ing head in, none of those 30k miles were easy miles....

 

What is the actual end goal power wise?

 

There never is one banny !! People always want more !! Lol

 

very true bro