What Can The 25 Head Rev To

[FineLine]

Throwing ideas out atm in regard to an engine I am planning. My original idea was to run a 26 head with HKS vcam but if the 25 head with the right springs etc can rev hard enough on hydro lifters it would be a more cost effective option.

WWhat sort of revs have you seen from a hydraulic lifter 25 head. I am thinking i need to get to around 9000 rpm to achieve the desired result.

[Simon-S14]

Use a neo head or convert to solid litters. Run some tomei procams and upgrade valve springs and you'll have no probs hitting 9k

[TiTAN]

the highest i have seen was daves rb25 and he took that to 8500 iirc

[R31Nismoid]

My limiter on a stocker head was 8200.

With some upgraded inaards & gizzards I cannot see why it wouldn't be possible. 10,000rpm would be getting expensive but 9k, should be quite achievable. But as said, start with a NEO perhaps? Would be the easiest way.

[PM-R33]

I got told my rebuilt head was safe for 8000rpm and it isn't really anything special. Don't see why 9000rpm would be impossible if everything was put together right.

But as others have said NEO head would be the best. Hell it's better than a 26 head; VCT + Solid lifters, win win.

[TiTAN]

I got told my rebuilt head was safe for 8000rpm and it isn't really anything special. Don't see why 9000rpm would be impossible if everything was put together right.

But as others have said NEO head would be the best. Hell it's better than a 26 head; VCT + Solid lifters, win win.

he wants to keep the hydraulic lifters and they can only be pushed so far before they dont open /close valves properly.

[NYTSKY]

Anything north of 8500rpm would be treading a fine line lol

See what i did there

[GTScotT]

As above, I would be confident in a simple solid lifter setup and some good springs. 9000 shouldnt be a problem.

We dont exactly have any solid grounding to back up hydros failing at or beyond 8500, but it seems we have results to support the UP TO argument.

I believe SimonR32 is squeezing 8200 out of a completely factory long motor.

[NYTSKY]

RB30 going to 9000rpm?

[FineLine]

RB30 going to 9000rpm?

Correction Dave, rb 30 something going to 9 grand. (wink wink)

Consensus is what I thought. the hydraulic lifter setup wont cut it. f**k the neo head. mismatched bloody thing it is. not enough plenum choices etc for them. If i am going solids the best bang for buck starting from scratch is a 26 head.

I already have a solid converted 25 head on the track car but that was because I already had the hot and cold side prepped for a 25.

[Simon-S14]

exactally whats wrong with the neo head?

[FineLine]

exactally whats wrong with the neo head?

Probably nothing simon but there has been precious little development done on it compared to the 25 and 26 head. Limited plenum choice is probably its biggest drawback.

To my thinking its the red headed stepchild of the rb heads.

[Simon-S14]

i got no issues with it so far. you can run a 33 GTST greddy plenumn easily enough. plazmaman make a plenum also. stock even works fine

[FineLine]

I wont discount it at all Simon. Its on the research list. Plenty of tme before I need it.

[Simon-S14]

for the record im making 370 rwkw (or 400 rwkw on a hub dyno) with stock motor and stock plenumn. mercuary motorsport did a VC commo with a neo motor with 700 + rwhp also stock motor but aftermarket plenumn.. so the power and flow is there. in theory the RPM is there also since its basically similar to an RB26 head

[FineLine]

for the record im making 370 rwkw (or 400 rwkw on a hub dyno) with stock motor and stock plenumn. mercuary motorsport did a VC commo with a neo motor with 700 + rwhp also stock motor but aftermarket plenumn.. so the power and flow is there. in theory the RPM is there also since its basically similar to an RB26 head

As much as I will look at the neo its unlikely i will go there Simon. I already have 2 hot and 2 cold side setups to suit the 26 so it would make sense to go that route.

[Simon-S14]

yeah theres no denying that its tried and tested. plus ITB's are cooler

for the purpose of this thread tho.. solids are needed for the rev limit your seeking

[FineLine]

yeah theres no denying that its tried and tested. plus ITB's are cooler

for the purpose of this thread tho.. solids are needed for the rev limit your seeking

Thats definitely the consensus both on here and with my builder. Solids it is.

[R31Nismoid]

Ah come on Simon you know that 370 is @ hubs (AMM's inflated Example 1 of 70rwkw inflated figures) and is closer 320rwkw like the 10 similar setups.

Anyways Noel - Why don't you just have an adaptor plate made up for the NEO? People have done it before (copies of the Blitz one).

You might wanna drop a PM to "Adz", owner of the wideboy 32 gts-t/stroker. I know he had at least one made... Perhaps there was a spare or a file you could get it redone from?

That'd work out in overall terms maybe 4-5k cheaper than going v-cam. Obviously v-cam is still better but it's a money for gain type of scenario and how far you going to go. There is always a (fine)line somewhere LOL... I did it too

[FineLine]

Jebuz I'm gonna have to draw a Fine line in the sand here, (shit now I'm doing it.

There may be other options to the vcam and the nissan setup soon Ash.

Whispers in the wind. (wink wink)