Unique Autosports Rb25det Exhaust Manifold

[Cubes]

I'm certain they are for the rb25 log manifold as the thread subject title does state rb25 stainless v stock exhaust manifold?!?

[legend01]

Hi Cubes

Sorry you are correct ,learn me for not putting on my reading glasses but I have them on now , well with that information it makes for an intresting comparsion ,I'll try listing all the figures I have now here and manifolds

SS high mount..SSlow mount....RB20....RB25.....rb25 extrusion honed...HKS low mount .....hks extrusion honed

1. 150.4............175.1.........159.7....159.7............175.3..................

...170.7....................194.8

2 234.9............164.2.........162.4....162.4............172.7..................

...166.2....................203.4

3 169.2............175.8.........160.7....160.7............179.7..................

...178.7....................198.7

4 176.6............140.3.........150.1....150.1............164.2..................

...183.6....................200.3

5 160.1............143.6.........149.9....149.9............155.8..................

...182.2....................207.8

6 180.4............145.7.........173.3....173.3............180.3..................

...184.7....................202.8

max veration

.......84.5.............24.5...........23.4.....23.4..............34.8..........

.............18.5......................13

Average

.......178.6...........159.35........157.45..157.45............171.35...........

.......177.81..................201.3

Well on listing all these figger's and comparing with figgers listed on the comparo thread Cubes supplied and the one's I have for the standard rb20det manifold and the figgers John had for a low mount ss manifold I beleive he might have errored on listing his manifolds with the rb25det one so here for this thread I've changed them arround as two were the same ,so you know which one's I swiched they are the sslow mount and the rb25 manifolds the rb25 reading the same as the rb20 now as I have both here now and have just measured them and can find no differances I've listed them on my finding's as the same so ner

anyway makes for an intersting comparo

cheers Peter

[khunjeng]

honed would be the go...i know it will flow better and I have looked at the results but I'm not sure what that will translate to in terms of real world driving... what about doing the inlet manifold at the same time...

if anyone knows of a decent place in melbourne..I will get it done and test it out.

[r33_racer]

yeh while on that...does anyone know of anybody else in australia that does extrude honing? Or are we stuck with only UAS, no offence to them.

[discopotato03]

Evolution of the SE-R Turbo part II , run a search on this and scroll down to the pic of the turbo and look at the article . It has links to the Extrude Hone mob and a bit of info on the process and applications . I think there's someone doing it in Sydney but can't remember who .

Cheers A .

PS can some computer person put up the link please .

[legend01]

AFE Abrasive Flow Engineering in Mt Druitt did my flow honing and does most of the major company's as well but I must warn you that major company's have prioity over the little man for repeat work as he had mine for a couple month's mainly due to deadlines for company's

[legend01]

http://www.nissanperformancemag.com/march02/projectser.shtml

[Abo Bob]

The basic theory behind manifold and exhaust pipe length tuning is based on organ pipe theory. A tuned length exhaust is literally that - a length at which the pipe has a natural frequency of resonance which matches the resonance of the engine at a particular engine speed.

Longer tube lengths pull the torque down to a lower R.P.M. range. Shorter tubes move the power band up into a higher R.P.M. range. The amount of straight in the collector extension can move the engines torque up or down in the R.P.M. range. Longer extension length will pull the torque down into the midrange.

Really most people design the intake, cams and header to be optimal at a certain RPM range as the standing wave can only be created at a single RPM. Good for dyno shootouts...not street driving.

IMO for street cars get a well constructed deisgn...not lips etc...nice joins at the collector and a design that suits your needs...i.e. low down torque and this will be fine.

Persaonlly I have had only minor gains (2-3%) from header/extractors bolt ons.

I think you've got the inlet and exhaust mixed up a little there man.

The reason behind equal length runners on the exhaust side is that the pulses of exhaust gas coming from the cylinders will arrive in the order they leave the cylinders and not bump into each other. In theory, with non equal length the pulses run into each other and create unwanted turbulence.

The story of the torque moving up or down the rev range is to do with short or long inlet runners. frintance, Rb25's have quite long runners under the plenum and if you put a gtr style one on (Greddy) you will lose some lo down torque but gain some up high. Some ford 6's (and plenty of other engines) have variable length inlet runners to get the best of both worlds.

[discopotato03]

I could never find conclusive proof but I believe all the shock wave tuning and other NA engine exhaust theories go out the window when there's a turbine housing/nozzle/turbine blades in the way . You can never have the situation where there won't be some slightly elevated exhaust manifold pressure that would not be there without the turbo . This is not to say that you can't have higher inlet manifold than exhaust manifold pressure and its this inlet side pressure bias across the cylinder head that makes scavanging work .

IMO its very likely impossibe to make a turbo exhaust manifold scavange by it self properly because you get a pressure rise of some kind just downstream across the turbine housing . I'm told it has to be this way because one of the most important functions the turbine housing has is to accelerate the exhaust gasses into the turbines inducer blades . I'd say the mythical perfect exhaust manifold is one that at worst has no constriction points other than a very slight cross sectional reduction in diametre all the way to the turbine housing . Corky Bell goes to say that the exhaust "putts" don't like to be slowed down and sped up because this costs velocity energy and also tends to pump a lot of heat energy into the manifold itself , heat energy that could be better used to drive the exhaust gas into the turbine blades . I believe the whole exhaust system from the exhaust valves to the exhaust tip should be treated as a single entity and turbo/turbine/housing are a major part of this .

Out of time cheers A .

[khunjeng]

I think you've got the inlet and exhaust mixed up a little there man.

The reason behind equal length runners on the exhaust side is that the pulses of exhaust gas coming from the cylinders will arrive in the order they leave the cylinders and not bump into each other. In theory, with non equal length the pulses run into each other and create unwanted turbulence.

The story of the torque moving up or down the rev range is to do with short or long inlet runners. frintance, Rb25's have quite long runners under the plenum and if you put a gtr style one on (Greddy) you will lose some lo down torque but gain some up high. Some ford 6's (and plenty of other engines) have variable length inlet runners to get the best of both worlds.

yeah I did get it around the wrong way I think....shorter with larger diameter = top end power.

[T04GTR]

The basic theory behind manifold and exhaust pipe length tuning is based on organ pipe theory. A tuned length exhaust is literally that - a length at which the pipe has a natural frequency of resonance which matches the resonance of the engine at a particular engine speed.

Longer tube lengths pull the torque down to a lower R.P.M. range. Shorter tubes move the power band up into a higher R.P.M. range. The amount of straight in the collector extension can move the engines torque up or down in the R.P.M. range. Longer extension length will pull the torque down into the midrange.

Really most people design the intake, cams and header to be optimal at a certain RPM range as the standing wave can only be created at a single RPM. Good for dyno shootouts...not street driving.

IMO for street cars get a well constructed deisgn...not lips etc...nice joins at the collector and a design that suits your needs...i.e. low down torque and this will be fine.

Persaonlly I have had only minor gains (2-3%) from header/extractors bolt ons.

its the other way around on the exhaust. short runners give a goodd kik but choke at higher frequnqes. idealy for a rb26 reving to 9k they should be around 20-25inches long and 1.1/4 inch internaly.

(dont ask where i got that figure from. was a engineer who does all that stuff ec etc.

i put that theroy to test on my dr30 with a 26 in it. with a t04e 60trim/o trim i made 326rwkw on 1 bar boost 550cc injectors maxed out.

now. t04z on 1 bar on an ebay manifold makes 315rwkw.

so smaller turbo on the corect manifold gives better power. but seouuly if there cheap enough just buy another one. my ebay ones not cracked yet. although it is ceramic coated

[T04GTR]

also.. its really pointless having cfm figures for a turbo maniflod. its presurised and has to go through a turbine.

but. from that list above id be leaning on the hks lowmount. nice and evan

[T04GTR]

http://www.uniqueautosports.com.au/priceli...tainlessman.jpg

MADE FROM 3MM THICK 321 PREMIUM GRADE STAINLESS STEEL.

x-force stylzzzzz

[khunjeng]

I was confused with pipe diameter and length which are all important factors. Just to confirm, high-revving horsepower can be had with headers utilizing larger diameter, shorter primary tubes.

lol...i still want some.

[SLY33]

Hi guys, got the stock extrude honed manifold back, apparently it looks sweet (i havent seen it yet) brother is getting some pics and i'll post results in detail, with before and after pics.

lowest flowing runner is now 190, highest is 220. Details to come....

cheers

[drgnball34]

Im going with buying a new exhaust manifold rather then extrude honing my old one. With the price it cost, a extra $600 for a new one gets my vote. Ebay has a genuine HKS cast one for $1150. Now thats about the same price for the 6boost ones! What are your thoughts about each one? Obviously the HKS would be first pick amoungst most people, but the 6boost looks like a different setup.

hks http://cgi.ebay.com.au/HKS-TURBO-MANIFOLD-...bayphotohosting

6boost http://www.horsepowerinabox.com/HPIAB2/category15_1.htm

[Cubes]

'Apparently' the R33's have issues with the HKS cast item as it mounts the turbo slightly lower causing the turbo to foul on something.

Check this isn't also the case with the R34's.

The HKS exh. manifold is definitely a good buy.

[drgnball34]

'Apparently' the R33's have issues with the HKS cast item as it mounts the turbo slightly lower causing the turbo to foul on something.

Check this isn't also the case with the R34's.

The HKS exh. manifold is definitely a good buy.

Can any1 confirm if this indeed is the case with the R33's and if it also effects the R34's?

[SLY33]

the HKS mani looks nice..

id get one but stock appearance is a priority in SA!

anyway here's the results of the port job, im quite happy with the end figures, pics to follow.

[drgnball34]

Spoke to the supplier of the HKs manifold. They actually do mount the turbo lower and on a slightly different angle then stock. In the case where im using a HKS GT2835 and turbinless kit...its pointless.

Longer oil and water lines need to b made

New dump pipe

Modify or Make a new intake pipe

Block off the external wastegate provision or Use an external gate and disconnect the internal gate. That sucks!