Hks Rb25 Exhaust Manifold , Worth It ?

[discopotato03]

Along with a few other usefull bits and pieces Ive had one of these stashed away for a few years now and I'm wondering if its worth doing with the IW GT3076R . I've been through most of the threads here to see if its worth doing for an "only" 300 RWKW engine .

Recently people like Mick o have smashed 300Kw with the std manifold so I'm wondering if going to the extra grief is worth it for me . I guess none of the available front pipes are going to work with it and I'm not going to use an external gate anyway .

It seems the dramas surround clearing the engine mount and shield with the compressor housings inlet boss and hose . One thing I picked up on is that someone , Nismoid I think , reckons RB26 engine mounts aren't as tall as RB25 ones so do we think a shorter engine mount and a spacer between it and the engine bracket would help ? Is an RB20 engine mount and bracket any better ?

The $64 question is does the HKS manifold make enough of a difference with an IW turbo to make it worth the effort ? I can see the draw if you intend to go external gate but not sure otherwise .

Wolverine do you have pics of yours in the engine mount area with the GT3076R ? I know you told me more fettling had to be done but can't remember the details .

Cheers A .

[wolverine]

You need to shave the engine mount a bit the rest is straightforward fabrication work for the exhaust. Go for it and buy a TS 0.82 housing and bobs your uncle.

[AngryRB]

Is there any internal size difference in the HKS manifold compared to stock?

wolverine- should I bother port/polishing the stock manifold and TS 0.82 ? My tuner told me to be careful I don't take too much off because ill loose response and it could affect the torque

Edited March 25, 2013 by AngryRBGTX

[wolverine]

HKS manifold runners flow more than a stock manifold.

DaleFZ1 has tidied up a stock manifold to remove obvious casting dags and basic port matching (if memory serves). If you are doing it yourself and are competent with a die grinder I reckon it would be worthwhile and unlikely to harm anything unless you get medieval.

Ultimately I have no doubt that a fancy manifold can be an improvement but for a streetable turbo realistically the money spent might not be that noticeable.

[Dale FZ1]

^+1

If you have the tools, the time, and the inclination then I'd say there is nothing to be lost by tidying the gas flow path in the OEM manifold. The runners can be made a lot nicer, and port matching is always going to help things.

I reckon the collector/merge area is not the nicest aspect of design from a flow standpoint although some judicious work with the die grinder should bring some improvement too. If you're doing the work yourself, look at the potential to pick up 10-15kW (tops) for free.

Bottom line is that if you were paying workshop rates to get it all done to optimal levels, you have blown a proportion of the cost of a decent fabricated manifold that has a decent gas flow path and collector already.

If you happened to have a cast HKS manifold sitting in the shelves however, you would be putting it to use without thinking twice.

[skyline32sup]

If you have the coin and want a lifetime warranty manifold go 6boost, I just ordered mine for my Rb25 with Garret 3076r .82 housing.

[discopotato03]

Does anyone know the real world performance difference of the HKS vs the OE RB25 exhaust manifold ? I mean in power or torque terms not flow numbers .

Also does anyone have pics of an RB25 engine mount next to an RB26 one to show up differences ?

Cheers A .

[Roy]

Well I am struggling to find Trust style turbine housings so happy to buy the mani off you so I can be like the rest of the world and run T3 flanged turbine housings the

[Roy]

Oh I will add whilst there are no direct comparisons that I know of. There are loads of 6boost vs std results to show that std is sh1t house. There are a few flow bench results of HKS v 6boost that show the HKS is a very good thing...so just use it or send me your bank details...as I should never had sold mine to Wolverine

[AngryRB]

so what would be the difference upto 300kw between stock and the 6boost? is it legal to have a low mount 6boost?

[Dale FZ1]

Mark, your sig indicates you are in Queensland. Low mount, high mount, its all legal. No good asking people based in Vic or NSW.

Regardless of whether its a HKS, 6boost, or a stocker with internal flow improvements, they are all going to make the engine exhale more easily. The flow efficiency can allow it to make more power, respond just that little bit easier, or use a little bit less fuel in general use.

Sometimes its going to be difficult to say X manifold will result in Y kW gain, and the cost:benefit analysis is hard to make. It's not that hard to conclude though, that if your setup is spec'd and tuned to run around 300rwkW and not much more, then you could find yourself spending 500-1500 for a gain of 10kW. That's not a good return on investment at the top end of the scale.

On the upside, there have been users posting up comments indicating that the gain in response and feel/driveability do not show up on dyno sheets.

[hypergear]

The HKS low mount is very difficult to fit. The Garrett .60 or .70 housing with a 4inch induction will sit against the engine mount. Not mentioning every thing else had to be custom made to suit.

Since doing the manifold and gate rout, better off getting a local hand made high mount item.

[discopotato03]

Do I get the feeling that this manifold was made with R32 GTSTs in mind and they used a slightly different engine bracket and engine mount style ?

Also I think these were sold in a kit with a T04E turbo that had a smaller inlet boss .

BTW I don't have the wastegate just the manifold itself .

A .

[Roy]

They do fit R32s no problem so probably were tailored for the R32

[jet_r31]

Did you ever dyno the HKS mani Stao?

cheers

darren

[hypergear]

It was a kunt to fit I spent 2x days on it:

making sure every thing is all flat and surfaced.

The oil port on the turbocharger get folded under the manifold that needs special fittings.

Position of the turbocharger held is only a inch above the oil drain port. That was a real kunt trying to customize a drain adaptor and pipe that doesn't kink and that short.

Turbocharger and all related bits needs to be fitted on to the manifold before bolting it up to the head. And then I found the comp housing is hitting against the engine mount.

So I ripped every thing out and bought brae high mount manifold. Life has never been easier.

The HKS stuff when on ebay. bidding from $1.

[75coupe]

Would love a hks mani to match all my other hks turbo and exhaust parts, all hks gear together seems to work excellent from my experience

[wolverine]

Of course once you have the manifold installed the exhaust path out of the turbo is a lot straighter so you win somewhere and you lose somewhere.

If you are changing turbos regularly then no way you would use one.

If you have a Stagea I wouldn't recommend it due to the location of the oil drain on those blocks. Otherwise like most car modifications....it requires modifying something.

[discopotato03]

Off my own topic I suppose but is much known about this manifold from Brae ? I'd always though it was impossible to make a manifold that mounted the turbo anywhere near the std position and have it work better than the std cast iron one . They say it mounts the turbo a bit further out from the engine but with minimum changes they can be made to work .

Some of that foil type quilted heat shielding would make it look a bit less lethal but its obviously not going to factory .

http://www.braeautofab.com/apps/webstore/products/show/2941402

Will reasearch these , cheers A .

[hypergear]

Yes that was the manifold he made for my car. I still have it. Its better then stock, how ever still no match for the high mount manifold that he makes.