Extrude Hone

[ovabooster]

I want to get a custom RB25DET manifold ( tuned length ) but people have said that it is not worth while if it is going to take the standard turbo position ( HKS GT2835 pros kit ). It wont be able to have decent runners or collector design? So I was thinking of extrude honnig the factory at UAS. Any one made any noticable power gains???? Also anyone here cracked over 300rwkw with HKS GT2835 .87 a/r cams etc? Ive been reading that the WG has trouble holding boost..How bot weliding shut the interanl and using a external WG???

[R31Nismoid]

I dont think anyone has done much testing back to back. ie, before/after exclusive.

Other changes were also made at the time so its hard to attribute a gain (if any) to one specific thing when 3-4 parts are changed.

IMO, its a waste to close the external gate on an int gated turbo.

You may aswell just begin with an externally gated turbo/manifold if thats the case.

Hyrid styles like that im not a fan of. It has been proven to work, but also if not done right can cause problems

[Cubes]

There is one bloke. I forget his alias. Orange R33 in his Sig.

I believe he had UAS power port/extrude hone his std exh. manifold but he is/was oversea's so he was unable to test.

He's running a gt2835 and currently making up around 280rwkw.

I'm very keen on seeing his results. Maybe UAS could shed some light on if the extrude honed std exh. manifold allows it to push considerably more than the 300rwkw brick wall the std exh. manifold usually see's.

[Angus Smart]

only problem with extrude honeing is that the bumps that would usually be taken out with a die grinder are still left in. unless they do that also!!

it opens the manifild up yes!

but doesnt get rid of bumps.

if you'd look in a gtr manifold for example there are many large bumps in there!

[Beer Baron]

yeah, speak to UAS. they have extrude honed heaps of stuff and have tested extrude honed stock manifolds on a flow bench to measure gains in both overall flow, and even flow.

[Butters]

I did a back to back on an SR20 manifold.

Overall I wasn't blown away with the results. There was definetly gains though.

The problem aparently with my manifold to begin with was the runners where all very un-even. So rather then focusing on increasing

the overall flow he spent the time making the flow even.

Gave me piece of mind that each cyclinder was getting the same amount of air but not massive gains to talk of.

As also mentioned there were still a few bumps left. The finish wasn't as mirror like as i expected.

Again though this could be because he was trying to make them even.

I've done a much better finish my self by hand but obviously I can't get to the area's in the manifold he can with the dinosaur poo.

Its definetly worth doing but I think only at the top end of the scale.

I would also hand port anything this time before i sent it of to be honed.

[Cubes]

Butters,

Was the manifold pushed to its limit prior and after?

The RB log manifolds for example really do struggle to push much over 300rwkw regardless the turbo bolted on their side.

[ovabooster]

how about power porting as another option? Heard it gives a better/smoother finish?

[Cubes]

Its the same thing.

The US call it extrude honing, we call it power porting.

[R31Nismoid]

Testing on a flow bench is one thing, but sometimes ends up different in the real world for whatever reason.

I'd like to hear if more people did actual back-to-back testing on a car

[Roy]

how about power porting as another option? Heard it gives a better/smoother finish?

Same basic process...but the Power Porting ppl claim to use a different medium

[Butters]

Butters,

Was the manifold pushed to its limit prior and after?

Yer pretty much. Car was making 400rwhp. It would lean over quite badly from 6500 rpm to redline.

I gained very little more top end hp at the same boost but the power drop of was much less dramatic, it made around 20 - 30 rwhp MORE at 7500 rpm.

Was trying to avoid buying a greddy plenum, as I have seen them loose a heap of power from 3500 - 5000 rpm due to the short runners.

Got me the result i want but I don't think its the ultimate solution for out right power.

Note this is SR20 info, so results may be quite different for an RB.

Edited April 4, 2007 by Butters

[ISL33P]

Was trying to avoid buying a greddy plenum, as I have seen them loose a heap of power from 3500 - 5000 rpm due to the short runners.

dont be fooled by the short runners theory.

i have seen short runner plenums make less lag, more torque and power creating some of the most responsive packages considering the other boltons used.

[dontfeelcold]

examples?

[OVL-747]

Was trying to avoid buying a greddy plenum, as I have seen them loose a heap of power from 3500 - 5000 rpm due to the short runners.

Got me the result i want but I don't think its the ultimate solution for out right power.

why are you concerned about 3500-5000rpm if your chasing outright power.

i mean , i understand its probably a street car and driveability is the main advantage ,therefore low/mid range is important, but if you want outright power at 7500 revs , then go for the greddy unit , with the short larger i/d runners.

anyway i had my old vl turbo plenum/runners power ported , and made a very noticeable difference over the dead stock vlt setup.

now with the newest setup on my car i have an aftermarket plenum , and that has also been thru the hands of andy sanders at specialised power porting.

im a firm believer that it works.

my compressor cover is also done.

[ISL33P]

examples?

my old car, several rb25s, rb30s, ca18s, sr20s (plus 2jz's, 4g63's etc etc) in Oz, Europe and USA.

one in particular vl (rb30) made 25psi by just over 3000rpm with a 35/40 and a 1.06 exhaust housing.

[Devils_Advocate21]

Nice results have you got any for the rb25?

[dontfeelcold]

Thats nuts. Was it your own design?

Edited April 6, 2007 by dontfeelcold

[Cubes]

sly33 is the bloke who has just had his std exhaust manifold extrude honed/power ported. ~34cfm increase per pot.

Legend also had some data on flow rates.

standard manifold .........hks cast ...............hks cast flow honed

1 159.7.........................170.7............................194.8

2 162.4.........................166.6............................203.4

3 160.7.........................178.7............................198.7

4 150.1.........................183.6............................200.3

5 149.9.........................182.2............................207.8

6 173.3.........................184.7............................202.8

http://www.skylinesaustralia.com/forums/in...t&p=2682373

also this link from UAS with some more data.

http://www.skylinesaustralia.com/forums/in...c=82555&hl=

Obviously flow isn't everything as in the real world merge has a large influence on overall performance of the manifold.

[ISL33P]

Devils_Advocate21 - refer to spoolup and 2bnvs dyno results, these are both 25/30's but you get the idea.

dontfeelcold - they sure are

but were are not here to talk about my plenums, mod's get the sh1ts and with good reason, i am just sharing what i have learnt from my experience.

as Cubes says, it is not all about flow or how evenly it flows on a bench because real world stories for turbocharged engines are a different ball game. there are plenums out there that flow very very evenly on the flow bench, wont name them but the 2jz ones made in the US are big $$$'s (read: rip off), but require adjustment to fuel distribution to the rear cylinders 5 & 6. then again you look at the flow results of several rb30 plenums that retain all or part of the standard runners which show variances from 3-8% and have absolutely no problem with distributing air which provides some of the best consistency between cylinders without adjustment of individual injector/s - poor old microtechs dont have that function YET

PS forgot to mention all those results are acheived with a 80mm billet throttle body....kind of makes you think what people say about big throttle bodies and short rrunners huh..........:):)

Edited April 6, 2007 by ISL33P