Did this as well after seeing your other video awhile back. Honestly not hard to with a dremel and carbide bits. Did slip a few times a knicked the mating surface. I did use a pressure washer for a few minutes to flush out sll the shavings before installing.
Did this on my previous 2 classics and noticed an improvement on spool and power, now I have a spec c, I feel slightly seen off by not being able to get easy gains anymore!
They still have this overlap and build up of back pressure issue that causes burnt gases to back up into the cylinders at around 400 bhp. It limits the power.
Dejavu I’ve just spent two days doing the exact same thing installed a grim speed up pipe and all new gaskets with a 3”turbo back exhaust love the scooby rumble . And just painted my forester sf5 sturbo Rivera blue Porsche colour with speedline mistral wheels .in my pic
Good stuff. The receiving end of other stock exhaust parts are also porting (or at least de-lipping) candidates. Eg at the bottom of the up-pipe you can see heat discolouration where more of the gas flows on the outside of the bend. The inner metal sleeve can have its 90 degree edge smoothed at that point. The top of the up-pipe is usually narrower than the entry to the turbine housing, so nothing to do up there.
Hi Duncan, would you recommend or do you approve of the HS 'trick' up-pipe (or what it is called now), or seen/mapped any customers cars with the up-pipe installed?
Have a question. In jdm Subarus can you get the single scroll 2.0 wrx sti in the blob eye model 2003? I no 2001-2002 has the single scroll Turbo. I want a blob eye with single scroll if possible
@@racedynamix thanks for the response. Yes but you loss the rumble noise and am also told that the twin scroll turbo to upgrade the turbo is very expensive and harder to find and you have to change parts pipe size etc but with the single scroll it’s all bolt on to upgrade turbo and same size up pipe down pipe etc what’s your views on this
The protruding lip on the entrance to the headers causes a disturbance to the airflow out of the cylinder heads. At a certain airflow this disturbance causes a build up of back pressure and stops old/dead air being expelled from the engine. Effectively constapation... therefore new fresh air cant be ingested, and more power made. Porting elsewhere in the headers and uppipe can be worth it but diminishing returns. It really depends on the power you are aiming for ... ?
Hi.. probably not worth it on a std car tbh. It is removing the restrictions that stop it making over 400 so not going to be a restriction for std set up.
Do you genuinely see much difference in tuning after doing this Graham - is it 'noticeable'? I admit I did it 'while I was there', when I replaced my awful JDM aftermarket header with an OEM STI one, including porting the cross pipe join, but I read lots of conflicting info that it basically achieves nothing.
Is there record of anyone performing a before and after to show what type of gain or benefit this will yield if any? IE: Dyno base pull before port and then again after.
One would think that anything helping the engine pump air more efficiently is a good thing. The lip on the exhaust manifold would be causing an immediate restriction on hot gas exiting the combustion chamber, so a fairly important area. Not everything is measurable by peak dyno power comparison. Usually dynos have a slow ramp-up and (at peak power) the wastegate is open , so inefficiencies are being covered-up a bit. Testing Brake-specific fuel consumption before and after porting would probably reveal more.
I should have said to blow the headers through with an airline before refitting to get rid of debris. sorry about that 👍
Did this as well after seeing your other video awhile back. Honestly not hard to with a dremel and carbide bits. Did slip a few times a knicked the mating surface. I did use a pressure washer for a few minutes to flush out sll the shavings before installing.
Did this on my previous 2 classics and noticed an improvement on spool and power, now I have a spec c, I feel slightly seen off by not being able to get easy gains anymore!
GDB? some of the best flowing factory headers, good for 500+ whp I was told.
Yep gdb, no point in changing them at my power level.
They still have this overlap and build up of back pressure issue that causes burnt gases to back up into the cylinders at around 400 bhp. It limits the power.
@@racedynamix EL or UEL?
uel have this issue. el are fine to around 500 but still can be improved with porting
I don't have steady hands 😂....this is going to be a job. I'm going to get booked with you soon. I'll happily sort out my maf scaling.
Cool 😎
Thanks Duncan I’ve had aftermarket headers crack on me before so I’m definitely sticking with ported oem ones
Yeah same. Cracked loads of sets of gt spec headers from various sources.
Dejavu I’ve just spent two days doing the exact same thing installed a grim speed up pipe and all new gaskets with a 3”turbo back exhaust love the scooby rumble . And just painted my forester sf5 sturbo Rivera blue Porsche colour with speedline mistral wheels .in my pic
Really cool colour 😍
@@racedynamixthank you 👍 goes well with the wrx gold speedlines I think. 4yrs in the making
Good stuff. The receiving end of other stock exhaust parts are also porting (or at least de-lipping) candidates. Eg at the bottom of the up-pipe you can see heat discolouration where more of the gas flows on the outside of the bend. The inner metal sleeve can have its 90 degree edge smoothed at that point. The top of the up-pipe is usually narrower than the entry to the turbine housing, so nothing to do up there.
Good points 👌
fantastic how to video, Duncan. thanks a million.
my pleasure 🙏🙏
Nice, all the small things add up. Is there any similar optimization for the OEM downpipe?
@@ruisu82 The cat in there negates any benefit from doing anything tbh
@@racedynamix Yeah that makes sense. Thanks!
Nice one buddy. I shall have to get you to sort mine out prior to a return to the Ring (travel 5th, chill 6th, full days 7/8th Sept)
Cool 😎
Old NASIOC threads say you can do the same in the mid and uppipe unions.
hi. Yes you can. The main restrictions are the ports that mate to the heads. If you are aiming for high bhp then that is worth it 👍👌
Sorry for always off topic questions but gear oil 02 5 speed and diff. Gl 4 or 5 and recommended viscosity
Hi Duncan, would you recommend or do you approve of the HS 'trick' up-pipe (or what it is called now), or seen/mapped any customers cars with the up-pipe installed?
@@u-an6821 mapped loads with it on. On a gt spec headers it def helps but I've yet to see any benefit over the std sti catlrss uppipe 👍
Whats your take on anti reversion lips on the headers?
Hi... Ive not seen any along these lines in the subaru world or talk of them helping tbh. So I havent tested I am afraid.
Have a question. In jdm Subarus can you get the single scroll 2.0 wrx sti in the blob eye model 2003? I no 2001-2002 has the single scroll
Turbo. I want a blob eye with single scroll if possible
Hi. No the blob eye sti is the better twin scroll version. Spools earlier, epic sound and a perfect street car imo
@@racedynamix thanks for the response. Yes but you loss the rumble noise and am also told that the twin scroll turbo to upgrade the turbo is very expensive and harder to find and you have to change parts pipe size etc but with the single scroll it’s all bolt on to upgrade turbo and same size up pipe down pipe etc what’s your views on this
Hiya Duncan what exactly does the help apart from de-restrict the exhaust gases, can I port anywhere else shooting for 400bhp+
The protruding lip on the entrance to the headers causes a disturbance to the airflow out of the cylinder heads. At a certain airflow this disturbance causes a build up of back pressure and stops old/dead air being expelled from the engine. Effectively constapation... therefore new fresh air cant be ingested, and more power made.
Porting elsewhere in the headers and uppipe can be worth it but diminishing returns.
It really depends on the power you are aiming for ... ?
@@racedynamix right I see now I’m looking at getting 400+hp. I’ll definitely do this ASAP.
Does has a benefit on my stock block ej25 2013 Sti ? If so will it harm my engine ?
Hi.. probably not worth it on a std car tbh. It is removing the restrictions that stop it making over 400 so not going to be a restriction for std set up.
@@racedynamix now that you are online ? How can i check if my turbo is in a good condition ??
Do you genuinely see much difference in tuning after doing this Graham - is it 'noticeable'? I admit I did it 'while I was there', when I replaced my awful JDM aftermarket header with an OEM STI one, including porting the cross pipe join, but I read lots of conflicting info that it basically achieves nothing.
Definitely needed for over 400bhp in my experience. Benefit below that.. Will have a before and after soon
Is there record of anyone performing a before and after to show what type of gain or benefit this will yield if any? IE: Dyno base pull before port and then again after.
just about to 👍
How big is the port exit on the other side of the gasket?
@@notsponsored103 you mean on the exhaust ports of the heads ?
@@racedynamix yeah
How far down would you blend into the runner ?
Not far down tbh... The main restrictions are at the entry point 👍
@@racedynamix any reason/gains to be had by doing this kind of porting on any of the other parts of the OEM manifold? Cross pipe, up pipe?
@@_Hani_26 it depends on your power target tbh. Those restrictions are much less but all counts if aiming for 600bhp.
@@racedynamixI’ve got a couple of OEM manifolds, might as well give it a try!
@@_Hani_26 👌
what is the benefit ot porting it?
They flow better and will make over 400bhp with supporting modifications/ turbo etc whereas without porting the back pressure build up stops that.
Would you see any Benefits doing this running under 400bhp?
probably improvements to spool and top end power
Probably some. I will be getting this car back o the dyno soon to see if any improvement around 340 bhp 👍
One would think that anything helping the engine pump air more efficiently is a good thing. The lip on the exhaust manifold would be causing an immediate restriction on hot gas exiting the combustion chamber, so a fairly important area. Not everything is measurable by peak dyno power comparison. Usually dynos have a slow ramp-up and (at peak power) the wastegate is open , so inefficiencies are being covered-up a bit. Testing Brake-specific fuel consumption before and after porting would probably reveal more.
We did back to back testing and we found it an absolute waste of time and effort.
By what data did you reach that conclusion? Peak power on a dyno for example?
It depends on the power level 👍
agreed, if you see the hole size on the head it will make sense, I still prefer to port though.