Stainless or factory exhaust manifolds, results inside.

[Boosted Zed]

If you believe that all Jap made bling items are best DON'T READ BELOW.

Flow Bench Test Results RB26 Exhaust manifolds. Test were done on a proper flow bench test at 25 inches of water. All figures are CFM.

UAS Extrusion Honed Factory Manifolds..................182.7.........167.4.........179.3....

Factory Manifolds.......155.7.......138.2...........150.1...........

Stainles Manifolds......160.4..........138.8.........170.0

To further put in perspective the extrude honed ones are also match ported and different amounts of extrude honing is done in each runner to bring up the most restrictive ones and less on the better flowing ones. Flow bench tests are done to test before and after. This helps even up and balance the motor when in real time, whilst increasing overall flow. Less restriction means less heat and more free power and less stress on the motor.

................... Max Variation...............Average.

UAS Extrude Honed.......15.3..................176.46

Stock..........................17.5 ................148.0

Stainless.....................31.2 ................156.4

Plus stainless manifolds are more likely to crack, they do radiate much more heat and can't be HPC coated to well if at all. Can't improve on stainless unless roughly made and have jagged edges which these did not, and can't extrude hone. More prone to cracking.

Factory ones unlikely to crack and don't radiate as much heat and can be high temp black coated so will flow a fraction better in reality and perform better as they won't cook the comp cover as much as stainless. As a general rule of thumb every 7c increase in temp you lose 1% of power and require larger intercooler to cope with increase in air temp coming out of compressor. Best part is much cheaper than expensive Jap Bling ones. It is possible that other stainless manfifolds perform better although I don't think they would.

We have simlar results which we will release soon for RB25 manifolds, waiting for the extrude honing to be done on a set to get exact figures. We have figures for stock and two stainless types tested.

Pic are stock manifolds extrude honed and high temp HPC coated.

[KING33]

Interesting read thank's john.

Was thinking about getting some HKS stainless manifolds but now i think it would be better saving the money and getting the factory ones power ported.

[Squizz]

Tell 'em the price son...

[someonestolecc]

So does that mean the stainless steel item was a Japanese brand name one?

[Boosted Zed]

Retail price is $520 a pair. Cheap compared to stainless ones and much better result, and when they are in your car you don't see them anyway even if you are into bling. A fair bit of time and money spent making flanges and jig for the manifolds to go on the machine. Note also this is Extrude Honing not power porting or sand blasting. A thick gritty paste is used on a big Extrude Honing machine and it pumps the gue forward and back for hours to get much smoother. This is done after match porting which also achieves gains although from flow tests results only about 1/3 of the gain. If you are on a budget though and your engine is apart you should at least match port to head and turbo.

[Ronin 09]

Retail price is $520 a pair. Cheap

hi john is that HPC coated as well or just honed?

[Boosted Zed]

hi john is that HPC coated as well or just honed?

No just honed prices and specs etc are here.

http://300zx.com.au/pricelists/pricelist_g..._gtrexhaust.htm

[Kaido_RR]

was the Stainles Manifolds, just a china copy style one, or was it something brand name like HKS?

[TTT]

since this is in the tech section rather than sales section, Can someone or you John, explain exactly what is "extrude honing"...

what does it do?

how is it done?

also, are the RB20 and RB25 exhaust manifolds identical?

thanks.

[Boosted Zed]

since this is in the tech section rather than sales section, Can someone or you John, explain exactly what is "extrude honing"...

what does it do?

how is it done?

also, are the RB20 and RB25 exhaust manifolds identical?

thanks.

http://www.abrasiveflow.com/services.htm

Not sure if same?

[lwells]

I'm glad this topic has come up again because I was going to post a question about GT-R manifolds in the original thread about extrusion honed manifolds that John posted. Despite having pulled apart the exhaust side of my car all of about 2 months ago, I think I'm going to have to do it again as I think the rear manifold is leaking. Its a shit of a job, so I am looking for an incentive

was the Stainles Manifolds, just a china copy style one, or was it something brand name like HKS?

I'd like to know that too. "Stainless manifold" isn't terribly descriptive John: are you able to clarrify exactly what brand the stainless manifold was?

AFAIK, the main options are:

1) Keep the stockers.

2) Go for the UAS extrusion honed versions.

3) One of many jap. manifolds.

Of the Japanese, the ones I have come across are from Silk Road (~$500 + delivery/charges), HPI (~$1500 + delivery/charges) and Garage Saurus (don't recall the cost): unfortunately none of them have any flow data on their websites.

To those who have replaced/changed their manifolds (with twin lowmounts): what did you use and what benefits did you notice?

Cheers,

Lucien.

[TTT]

I see.

fancy word for sanding..

hahaha just kidding.

so instead of some sort of rought material, your company or people you use for extrude honing, is using some sort of "gritty gue" to get an even more smooth surface inside the exhaust manifolds.

Apart from the CFM figures, will you be able to provide a RWKW figure for those of us that will be after dyno figures (not me but I'm sure you'll find the same thing here as with the plenums)

will you eventually get a GTST or GTR with stock manifold and only replace the stocker with one of your modified ones and have before and after dyno readings with everything else being equal like boost etc?

You also mentioned that you do different amount of honing on each runner to bring up the most restrictive ones..

and yet the CFM results still show uneven amounts per runner.

using your results above of...

UAS Extrusion Honed Factory Manifolds..................182.7.........167.4.........179.3....

Factory Manifolds....................................................155.7.........138.2

........150.1.....

that is an increase of ............................................27.0............29.2...........29.2

That's not exactly that different amount of honing per runner.

I may be mis calculating something..

correct me if my example is wrong.

also, when extrude honing an exhaust manifold, are you aiming for "EQUAL" CFM for each runner? and also trying to get MAX cfm when doing so?

so in a perfect world, would you have wanted all 3 runners to have 182.7 CFM figure?

cheers.

sorry for all the questions.

gotta learn somehow.

[Ronin 09]

http://extrudehone.com/afmpro.html

Not sure if same?

So you're not sure what you / someone you're contracting to do the work for you, is doing exactly?

[Boosted Zed]

So you're not sure what you / someone you're contracting to do the work for you, is doing exactly?

They are exclusive to us we are geared to retail and answer questions and send out and do exchange etc and James from Abrasive flow is best at doing the work, so we keep our hats on at what we are both best at.

GTST It is not possible to get all runners the SAME we aim to getting them much closer as you can see.

I don't know the brand as nothing on them apparently and I did not see them myself. They were not new ones. If anyone has some stainless ones we will test at no charge and report results.

[Sydneykid]

Hi John, this might sound like a strange question, but which way did they test the flow? In the direction of the normal exhaust flow? If so, how did they block off the 2 cylinders they weren't testing? If they blocked off the 2 non testing cylinders at the cylinder head flange, then I am not surprised that the centre cylinder flow less. The aerodynamics of the manifold would cause that.

The only real way to test flow equality it is with all three cylinders being used in the same time frame as the cylinder firing. But that would be difficult as the primary runners are not the same length, hence the pulses would reach the secondary pipe at different intervals, ie; create interference.

Perhaps a better porting result would be achieved if the primaries were of equal volume, as this would give the same result as equal length. That is where flow testing of equal length primary pipes, as you would find in any decent stainless steel pipe manifold, won't show up their true advantage. Flow rate is not the only gain to be had from equal length primary pipes.

An example, the GTSR Group A exhaust manifold barely flows any more than the standard RB20DET exhaust manifold, but they make 25 rwkw extra. Why? Because of the extractor effect of the equal length primary pipes.

[Scooby]

Apart from the CFM figures, will you be able to provide a RWKW figure for those of us that will be after dyno figures (not me but I'm sure you'll find the same thing here as with the plenums)

will you eventually get a GTST or GTR with stock manifold and only replace the stocker with one of your modified ones and have before and after dyno readings with everything else being equal like boost etc?

Bless you GTST, I knew someone had to ask about the main game ie performance sooner or later.

John, I'm not trying to in any way oppose what you have posted here but can you answer Abo Bob's question or not? If I was a bench racer / professional air mover I'd be there this arvo with the $ to get a set of these. But since I only want to use a flow bench to move air to increase performance (and remember air under vacuum behaves differently to air under pressure) , you have given me no real reason to spend money. Please help rectify this for me. Or indeed most of us whom I suspect will beat a path to your door if you can provide results.

Or should the start of this thread read' all those who are prepared to spend their money on something that moves air really well but has not been proven to increase performance read further'?

I'm a fan of the original manifolds for the reasons you have stated. Prove to me that the extra money to get them honed actually works in the real world and you can have my money today. Or tomorrow, whatever works for you. Alternatively, tell me what you reckon I should see at the wheels + or - 10% and if you're right I'll pay, if you're wrong I don't but you can have my old manifolds. If it works this is a no risk proposition for you.

Remember, no offence meant.

Regards

[Abo Bob]

Hmm, I haven't posted in here yet Scooby.

John, another contentious thread. You can't help yourself .

SK, no it's not a perfect test but what is?

It seems to me that the only proof people here will accept is:

1. Dyno car.

2. Do the manifolds.

3. Dyno the car again.

4. Overlay the two runs.

5. Post it up.

I would personally have no problem with a retune of whatever engine management you have in between 2 and 3 but some might.

Some pertinent before/after temperature measurements might be helpful but difficult to provide.

[Scooby]

Hmm, I haven't posted in here yet Scooby.  

Sorry mate, quite right. Doh! See my edit, done before I saw your post!

John just dyno the things. Please.

[Guest Mashrock]

yeah i found that on my car it still uses the factory ones, and also the factory dump pipes too.

but yet the car does make alot of good solid power

and is quiet possibly i could already have some type of modification to the std extractors like this.

[dnb]

there is also specialised power porting in buninyong vic.

he does great work.

i also agree that a flow bench test on an exhaust manifold testing one cyl at a time proves little