Extrude Honed Stock Rb25 Manifold Results

[Cubes]

I'm curious to see how many people are running more than 300rwkw through the standard exhaust manifold, regardless of turbo.

Mine made 302rwkw @ 17psi with the std log and GT3076r .82 with 265 8.9mm lift cams. Can't run any more boost due to the internal flapper blowing open.

Two others on the same dyno but with a GT35r .82 both internal gate and with cams.

One cracked 330rwkw on 20 or 22psi with 265 9.3mm lift cams the other 18psi 312rwkw but he had smaller 260duration cams.

All on pump 98ron fuel and all are running an RB30det with the r32 rb25de head.

With WMI or 100+ron fuel no doubt it will be a different story. I have E85 down the road so first up going to fit a stiffer actuator and then retune on pump; Then throw larger injectors at it and push in some E85 to see what the lowly GT3076r can do.

However I have been told its a bad thing to be too restrictive (push the limits of the hot side too much) as you can induce a little valve float on the exhaust side and if pushed out at the track you may end up dropping a valve. Likely not to be evident on the dyno but once things all heat up top end power will be down and pop.

The GT3076 is only really good for 320rwkw on pump so it 'might' make the power a little easier with the extrude honed log.

I would be interested to see the GT35r .82 on the extrude honed exh. manifold.

[PSI Parts]

Interesting. We should be pushing 330rwkw with a hiflow using the standard manifold. Depending on time I might do a back to back dyno run with the extrude honing, which hopefully dispels all the theories floating around. I'm not really fussed about overall power, its the dyno sheet curves that should tell the story.

[Adriano]

330rwkw with a highflow?

[PM-R33]

what highflow u using for that?

[R31Nismoid]

Im not that confident of 330rwkw through the rear housing even ported to oblivion

Be interesting to see.

[tridentt150v]

Even if you don't see more peak power, I think you should see a smoother power delivery and an better fuel economy because the induction/emission system is operating more efficiently.

I have an extrude honed HKS cast low mount, but I don't have back to backs sorry. I had it honed before I installed, and I changed turbo's as well [hiflow to GT3076 WG]. I wasn't really looking for outright power, but as above.

Plus if in the future I do increase power [RB30 likely], my manifold is one less thing to think about.

PS I was on 290+ but had too much knock [no WMI], so reduced to 275.

[Cubes]

Trident.. Get some cams in to it. I was able to push in a heap more ignition following the cams. Unless your running the .6 rear I forget.

[R31Nismoid]

Even if you don't see more peak power, I think you should see a smoother power delivery and an better fuel economy because the induction/emission system is operating more efficiently.

Not necessarily. End of the day your governed by the rear housing port on the turbo.

Seen how small and tight it is at its smallest point? No matter how fast you get the air too or (or how much) its still limited simply to how much the rear housing can actually flow, more air you get there that cant flow, more pressure your creating everywhere

[PSI Parts]

Well 330rwkw is the goal, I'll be happy with around 310 though. Full details on the turbo and its availability should be out as soon as all the parts are finalised. It will be sold as a complete kit including the front/dump pipe. More on this later...

[WARLORD]

any one know where to get a manifold extrude honed in sydney.thanks

[discopotato03]

Debatable I know but I reckon Garrett would be foolish to make petrol spec turbine housings with larger volute passages than the mount flanges inlet port could feed .

I know people fear the dreaded "turbine lag" but it's really the only way to reduce turbine inlet (exhaust manifild pressure) to a minimum . I still don't think it's sufficiently well understood that lowering the "TIP" nearly always allows you to run closer to best mean torque (BMT) timing numbers AND it helps pull up the bottom end torque previously gained from a lower boost threshold .

About the best relivant example I can think of is using the larger VG30 OP6 type turbine housing on RB25 turbos or the GCG Hi Flowed RB25 turbo . If tuned properly generally the power goes up because the TIP goes down , also when it does the waste gate gets an easier time because it's not trying to "throttle" the exhaust gas as much .

We all have to remember that a waste gate is a means of controlling compressor speed , it is not and cannot double as an exhaust side pressure relief valve - not if you want it to control compressor speed and therefore boost . They are referenced off positive inlet manifold (or comp housing) pressure and have complete disregard for TIP .

Sorry getting OT , end rant , cheers A .

Edited September 14, 2008 by discopotato03

[R.I.P.S NZ]

I'm curious to see how many people are running more than 300rwkw through the standard exhaust manifold, regardless of turbo.

Ive done a 10.2 @ 134mph in a street GTS4 through a totally stock unmodified RB20 cast exhaust manifold with a T3/T4 hybrid turbo and power was around 450awkw

Video's are on youtube under R.I.P.S GTS4

Rob

[The Mafia]

well, I Made 314rwkw at 18psi on a stock RB25 manifold, and with a GT3037 with a little 0.63 IW rear.

I've run it up to 22psi for a few months, made heaps more power but I never dyno'd it.

Everything seemed fine. Just remember, the bigger you go on the manifold, the more its going to add to lag.

[WARLORD]

a bit of a update on a old topic but...... i just spoke to Abrasive Flow Engineering who does or did work for uas on hone and extrude and his exact words are for a rb25det manifold.

"""don't wast your time and money they don't flow as good as a hks manifold ""

and

"""for $900 to extrude and hone i would go and get some thing better"""

f#%$ me.this is from the guy who does them while some companies are begin for work due the the $$$$ crises this guy has shocked the sh#@ out of me so ..........after reading this post and many like it over the years and looking at the figures people have posted on flow have we all been grossly mislead by people in the industry have figures been made up for the trusting customer.

what is one to thing !!!!!!!

[rev210]

a bit of a update on a old topic but...... i just spoke to Abrasive Flow Engineering who does or did work for uas on hone and extrude and his exact words are for a rb25det manifold.

"""don't wast your time and money they don't flow as good as a hks manifold ""

and

"""for $900 to extrude and hone i would go and get some thing better"""

f#%$ me.this is from the guy who does them while some companies are begin for work due the the $$$$ crises this guy has shocked the sh#@ out of me so ..........after reading this post and many like it over the years and looking at the figures people have posted on flow have we all been grossly mislead by people in the industry have figures been made up for the trusting customer.

what is one to thing !!!!!!!

I am interested to know if the place doing the extrude hone has a flow bench. If they don't have a flow bench,then dispite what the bloke might of told you , he wouldn't be in a position to know anything.

If they do then that could save people some money for sure.

[tridentt150v]

Trident.. Get some cams in to it. I was able to push in a heap more ignition following the cams. Unless your running the .6 rear I forget.

Old one, but I had and still have cams Tomei 256/8.5mm units maybe a bit mild but hey!!!

I also have the larger exhaust housing 0.82 so that is not the issue, it just dets, but I'm closer to my WMI kit now - just had to buy other [non car related] stuff first.

As I stated, I don't think you'll see any power benefit from extrude honing, what you should see is an improvement in efficiency = fuel economy/lower ramp levels/etc etc but it would all be marginal. And it didn't cost me $900 - sounds like we need more extrude hone businesses in town to raise the competition bar.

[wolverine]

i believe i have the HKS manifold the Abrasive Flow guy extrude honed and flow benched.

before, it flowed more than the extrude honed standard RB25 manifold.

after, the runners flowed more and the % difference in flow was much narrower.

the goss i heard on Abrasive Flow is he has been busy doing LPG installs and has been flat out, therefore doing something profitable while oil prices were higher (apologies if this info is incorrect).

[tridentt150v]

That was one of the biggest benefits [if your car could use it], the difference across the runners. The HKS cast low mount has the best results for a manifold both in outright flow and balance for each runner.

However I must qualify that by stating that not all exhaust manifolds have been tested. The test results I found [on the UK GTR web site???? and this was like several years ago] only compared a well known stainless steel top mount, a std cast unit and the HKS item. It compared them all before and after extrude honing, but some of the top end units being made by the likes of 6boost and GCG may well flow just as good........we just don't know.

Wished I'd cut and pasted that results table now, would have made good reference material.

Wolverine I honestly think you have the best known system if you have a HKS cast low mount, there is none better [there may be some that equal, but we don't know].

[Cubes]

Trident...

Have you had a play with the cam timing?

[T04GTR]

so.... put simply does it work or not? considering the turbine housing is the bottle neck....