Rb25det Vs. Neo - Why The Power Difference?

[sneakey pete]

Well your saying that what they did flows better, so is more efficient to meet emissions laws, and also makes more power.

20wk from the tiny amount of difference your saying there is i feel is a pretty hefty increase isnt it?

All i was saying is that if they went too far then the car would make more power and on paper have more then the GTR lol.

20kw including a new turbo

[R31Nismoid]

^^ exactly, new turbo.

Which is what came up on page one as the major overall/influencing difference

[Lithium]

To date I am yet to see a STD r33 rb25 produce more than 270rwkw, using a HKS GTRS, on 3 independant dynos, like mine has done.

To be fair though, you've generated a bit of a strange bunch of variables to have to meet. I am sure there are plenty of standard R33 RB25s that have made around 270rwkw with an HKS GT-RS, they just haven't decided to go and get runs on different dynos as most people stick to a single tuner. I remember years ago when I was researching turbo upgrades for R33 RB25s 270rwkw seemed like the number to go for with one but I decided the GT-RS would start wrecking the fun when I got more power hungry.

I'm not sure what you are trying to prove, its known that R33 RB25s are well capable of going over 270rwkw with a standard head so the engine is not your limiting factor in this case.

[SLAPS]

IMO the Neo head is the way to go if your going to modify.

Cams - Neo the duration is less however lift is up as is ramp rate due to the neo's solid lifters

We should all know ramp rate and lift is the key to making good power with turbo charged motors. Duration is bad.

Stock they are very similar. The increase in power is a combination of the head, cam timing + slightly larger turbine to get those gasses out a little quicker.

Once we shove on a larger turbo and a pair of cams in the Neo head the Neo waves good bye to an rb25 modified with near identical mods, there's no comparison.

The Neo make power easier with better average power over the hydraulic head.

Edited March 14, 2009 by TheRogue

[Lithium]

Yeah I can see that it should do, just find it interesting that although I haven't seen a huge amount of results for Neos running upgraded turbos etc - none of them so far have been that flash. Definitely not anything substantially more than R33 RB25 results, people have even given examples in this thread.

[lcy]

I was told that the Neo engine is higher compression hence more knocking when more parts are modified? = rb25det > rb25det Neo

izit true.

[R31Nismoid]

In terms of todays fuels, not really. Quality is much better than the mid 90's when non-neo was being produced!

Most rebuilds etc involve a comp increase, even with bigish boost (18-24psi) due to the much better fuel's avaliable letting things go much nicer

So the higher comp would make a difference in say... 1994 with knock, but not in 2009

[discopotato03]

A while back I asked around and no one (engine builders/machinists) could quote exact differences between R33 and R34 RB25DET heads - from a valve size/compression ratio/porting perspective . I wouldn't have thought that Nissan would've spent the money on an engine family that was not going to last more than a few years .

Anyway the general feeling is that the larger OP6 sized turbine housing will help make similar power R33 vs R34 but there would be a slight turbine lag penalty .

When I first read about the R34GTts std power output (~ 206Kw) I thought thats what R32 GTRs made and went looking for the torque numbers to compare . I can't remember the figures but am sure the GTRs was higher .

Cheers A .