Gtr Factory Exhaust Manifold, Turbo Side Porting

[godzl1975]

I just did this to mine....matched ported the inlets and turbo flanges..and even done the metal HKS gaskets...was easy when taking the turbos off the carbon deposit that was left on the manifolds and gaskets pretty much outlined it all.

I used a dremal with a tungston carbide tip that was alot better that the grinding stones that you can get from supercheap, which are no use at all.

Found a store at minto, that sell only abrasives..got the proper grinding stones and the tungston tip from there...$3 for stones...and $15 for the tip.....the stones last a very long time and are the proper ones to get.3mm size shanks.

too bad only just read this, i have just finished putting back my turbos. could have taken some pics.

[discopotato03]

Just for the record if you want GTSS performance buy the 707160-9 turbos from Garrett - they ARE GTSS turbos minus the HKS actuators .

Cheers A .

[JimX]

Found a store at minto, that sell only abrasives..got the proper grinding stones and the tungston tip from there...$3 for stones...and $15 for the tip.....the stones last a very long time and are the proper ones to get.3mm size shanks.

too bad only just read this, i have just finished putting back my turbos. could have taken some pics.

Have you got the details for the shop at Minto? I should get some of those tips for future use, but also other people that might be reading this thread could make use of the info. Notably the 2 people that voted with the gung ho option

It is good to see that other people have already ported their manifolds. Makes me feel like less of a leper. Or if I still am, I'll just join you other DIY lepers in the colony.

[heller44]

DIY leper all the way.

Add that to the list, Rewiring the cluster, 044 intank with custom machined fittings, fitting the turbos completely opposite to what the service manual says, coil pack repairs, etc..

If you use common sense, think about what you are doing, and are prepared to replace any parts that you break along the way you can't go wrong.

Only things I have gotten others to do is fit the suspension (pain and it needs to be adjusted then), and to fit the clutch and tune it. I really don't like the idea of that heavy gearbox under the car in my shed.. bad enough when I was playing with the old single rail and t5's.

[giant]

we run standard r32 manifolds too, just cleaned up also.

we actually lost response and low down power with some other after market manifolds.

Edited July 22, 2008 by giant

[Shakiel]

we run standard r32 manifolds too, just cleaned up also.

we actually lost response and low down power with some other after market manifolds.

When you say cleaned up, was it the same sort of process as what people have been posting on this thread?

[den001]

bump this thread, good read and useful info... also looking into doing the same mod to my manifolds, i have a spare set that came with my -7's and would like to get the ported for more flow......

IMO i think its a win win situation porting the manifolds, as you are essentially removing any areas of teh metal which will cause turbulence, thus this should create a smooth interrupted exhaust velocity speed directed directly into the turbo........

i read in a book somewhere about air velocity speed that this can also work,

air speed can be accelerated bu using a unique design on say a pipe....

lets say we used a 45mm opening to get air thru a pipe, now, say that pipe is a sweeping bend like most manifolds, and this pipe so to speak was something like300mm long, say if we smoothly tapered down to like 42mm half way thru this pipe and opened up again to 45mm on the exit of the pipe, the air speed would be faster in a forced environment, if this is true, you could essentially get the turbos onto boost easier and also have no restriction up to at all...

if this is true, which i read in a book years ago, i wish i could find it, would it be beneficial to open up the ports on the manifold where it bolts to the head say afew mm to compensate for the larger port size in the head,, smoothly taper down to the standard size, ( cleaned up abit) then once again opened up to flow smoothly into the turbo housing like you boys have been doing so far????

just a thought

Edited July 29, 2008 by den001

[andygtr93]

This completely works. When my stock rear turbo died and I was low on cash so I decided to just replace with another stock turbo. Whilst everything was apart I opened up both the manifold, and the turbo slightly, and once it was back on the road, I was hitting full boost almost 1000rpm earlier. Although it is true about faster air flow when there is a thinner section of pipework ( a venturi) for a turbo to spool well, it requires a greater volume of air to pass by the exhaust wheel. The bigger the path for the air, the better the flow, and the earlier the boost comes on.

Having said that, it would have been a good idea to either block the exhaust side of the turbo from any shavings, or take it apart and blow the shavings out before refitting to the car. After 2 months of having the car on the road, the rear turbo let go again and was found to have shavings blocking the oil return to the engine.... oops

GT-SS going in now though, I might be more careful when matching these turbos to the manifold

[BoostdR]

I've posted this before in my T618Z 10cm2 vrs HKS GTRS thread....search function isn't working for me though.

We flow tested some Chinese stainless rb26 manifolds and the flowed twice as much as the std cast items. We then spent 6 hours porting the cast manifolds-taking the bumps clean off the head side, opening right up the turbo collector paying attention to the wall thickness with some pinches. The greatest increase was had from the short turn....huge amounts can be taken out. They were reflowed and came up within a few cfm of the stainless items. With the energy retaining benefits of cast over stainless, I know what I will be using. The runner diameter was not increased at all.

Matt

[dorifticon]

I had a crack at porting out my turbo flanges on the exhaust manifolds. I didn't really do much other than remove the "lip" that is on there. Matched it up to the HKS 2530's that will be going on there. Probably increased the surface area of teh flange by about 15%?

Used an air dye grinder and tungsten carbide tip as well - went through it heaps easy and way neater than I thought.

Pics:

Edited September 17, 2008 by dorifticon

[JimX]

Oh something I found a few weeks ago but forgot to mention in here, it seems that there is a reason to be doing this mod. Looking at the pic that I've attached, the N1 manifold seems to simply be the factory manifold with the same bits ground out. Pic found here - http://gtrusa.blogspot.com/2007/11/rb26det...ths-truths.html

Also I'm wondering if the people who I have heard complain that the 2530's are laggy on GTR's are running the stock manifolds? (this includes the person I bought them from, I think he changed to GT-SS's). Because I find it hard to tell that my 2530's are any laggier than the stock turbos. There are times where I think they are even more responsive than stock. Some of that would be due to the ball bearings vs plain bearings, but I also think the ported/matched exhaust manifolds would have a lot to do with it.

Anyway looking at this photo, I think that if anyone is thinking of buying N1 manifolds, don't pay any more than you would for a good porting job because they seem to be exactly the same thing aside from the size of the turbo flange hole.

[godzl1975]

sorry forgot about this...maybe for future reference..the place i got the carbide burr was at

APA (all purpose abrasives)

25 lincoln street

Minto 2566

(02) 98201532

[GTRsean]

My manifolds got the treatment too, did this when I was waiting for parts to come in. Took me a couple of hours.

[Marko R1]

this thread is a very good read (8 month thread resurrection) - i was searching for 'stock matched vs aftermarket' & this answers my question

im at the juncture where i need decide on which way to go & it seems that port matched/extrude honed stock manifolds is the answer for my new setup...

if its good enough for Mark Berry's racecar & the others on this thread (BoostR, dirtgarage etc) well that is good enough for me

there would be nothing worse than cracking a set of expensive tubes (although probably not as common as i think) THEN having to replace whilst in the engine bay

[Phobic]

sorry to redirect the thread another way but has anyone taken to the exhaust and inlet ports on the actual head themselves?

[Beer Baron]

I am in 2 minds at the moment. about to bolt on a set of HKS GT-SS, tomei expreme manifolds and tomei dumps to my heavily ported head.

I used the tomei manifolds on my last set-up which was very similar. it had ported head (a bit milder than this one though), tomei manifolds, HKS GT-SS and tomei dumps. it was very responsive. the path through the manis is very direct and they are very open so the exhaust gas is hitting the turbine very hard. the turbine entry on THE GT-SS needs some opening up itself. and you can see the turbo mount flange on the tomei manifolds is huge next to a stock one.

for this engine I'm thinking of trying stock manifodls ported out. but on the other hand the tomei mani's are a work of art and seem to work pretty well.

[Dale FZ1]

for this engine I'm thinking of trying stock manifodls ported out. but on the other hand the tomei mani's are a work of art and seem to work pretty well.

Up to a certain power level, the basic engineering (shape and cross sectional area) should flow heaps, with the restrictions multiplying at each poorly matched junction (ie. head to manifold, manifold to turbo, turbo to dump). At the factory rated power level it wouldn’t be a problem, but proper finishing work = “free” power due to efficiency gains.

I reckon you’re in the box seat Richard, with that Tomei gear at your disposal, but the guys who are cost-limited surely wouldn’t be too far behind with a set of properly finished stock cast items? Be interesting to see which way you go.

I like the general way GTRSean went with port matching, but going off pics maybe needed some more work around the short side radius at the collector? Those sharp edges looked a bit abrupt.

It’s great to see guys getting their hands dirty, learning what makes their car go, and sharing the experience.

[Marko R1]

beer baron - if i had a set of aftermarket tubes & they have been fine i'd stick with them!

my stock items have been port matched & now i need to find someone who can extrude hone them, i spoke to john from UAS who no longer offers this service...is there anyone out there who can point me in the right direction for extrude honing?

if it helps, i live in sydney

[proengines]

beer baron - if i had a set of aftermarket tubes & they have been fine i'd stick with them!

my stock items have been port matched & now i need to find someone who can extrude hone them, i spoke to john from UAS who no longer offers this service...is there anyone out there who can point me in the right direction for extrude honing?

if it helps, i live in sydney

I just remembered the guy who did extrude honing in Sydney had stuff for sale on ebay, maybe he has closed up. I bought a machine a few years ago but the cost to run one and the jigs you needed turned me off it so I sold it again.

Here's a graph of your head Marko with the port and no manifold, port and std manifold and port with the runner and outlet opened up, not a massive difference with the porting, there is some though. The manifolds are a definite restriction though as you can see in the graph. I'd like to test those 6 boost twin manifolds, they really look the goods.

[Dale FZ1]

I'd like to test those 6 boost twin manifolds, they really look the goods.

Can you find or post up any pics? Be interesting to see.