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Discussion Starter · #1 ·
The "Must Have" exhaust system at the moment seems to be the APS 3.5" full system.

However APS also make a 3" system. Lots of people on the forum are running 3" miltek's systems etc with good results.

I don't understand at what point is it benificial to move from a 3" system to a 3.5" system? And also, there is the turbo elbow debate about the actual diameter of the turbo elbow outlet. (If the turbo elbow outlet is less than 3.5", what's the benifit, to fitting a 3.5" downpipe to it?)

I've just received a 3" Magnex downpipe, to fit to my system with the already fitted Magnex de-cat, coupled to the HKS centre and tail section.

Now Ashleyy's Evo VIII was running about 400/400 with the HKS centre and tail section, admittedly he had comprehensive mods, including the turbo elbow and downpipe. ??

I'm trying to make my system 3" right through, as I can't afford or justify £800-£900 for the APS 3.5" system at the moment. Just wanted to know the performance gains with the 3.5" over 3" systems.

What we really need, is a back to back test of a 3" vs 3.5" system
on a car. After all APS sell 3" and 3.5" systems but why. Personallly I would have thought that they would have only made the bigger size :confused:

Please enter the debate :D
 

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3" will fit a ix but the 3.5" wont as it fouls rear defuser. dont think this is why the 3" was developed but useful to know.

i neally ended up with a 3.5" which wouldnt have fitted, thanks to marcus at extreme who got one tried on their demo car all was ok and i got the 3"

really good stuff though and really pleased with the quality
 

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Discussion Starter · #3 ·
just got a viii said:
3" will fit a ix but the 3.5" wont as it fouls rear defuser. dont think this is why the 3" was developed but useful to know.
Interesting,

Those APS systems do have the tailpipes coming out of the rear bumper area, at a funny angle though, don't they?

In reality though, the 3.5 inch system should fit on the ix if the tailpipe was straighter then? Is that what you're saying?
 

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BHP,
I had a 3.5" APS fitted as opposed to the 3". Reason? Because it was bigger :D

Does it make more power? Who knows, but if I had bought the smaller pipe I would have always had this doubt in my mind that I should have gone for the bigger system.

At least it shouldn't make less power!

Now, as to back to back testing, is it the right thing to do just to swap it around and stick it back on the dyno? Or does the car need to be re-mapped to enable the "mod" to realise its full potential.

Then you get the arguement that the increase was due to a better map, and not the pipe etc. But, what do I know, I'm not a tuner.
 

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Discussion Starter · #5 ·
Paul_G said:
BHP,
I had a 3.5" APS fitted as opposed to the 3". Reason? Because it was bigger :D

Does it make more power? Who knows, but if I had bought the smaller pipe I would have always had this doubt in my mind that I should have gone for the bigger system.

At least it shouldn't make less power!

Now, as to back to back testing, is it the right thing to do just to swap it around and stick it back on the dyno? Or does the car need to be re-mapped to enable the "mod" to realise its full potential.

Then you get the arguement that the increase was due to a better map, and not the pipe etc. But, what do I know, I'm not a tuner.
True I guess Paul.

Would be interesting back to back on standard ECU settings (like the difference between FQ300's and FQ320's is only exhaust and filter)

Then maybe 3" system with Ecutec'd ECU.
Then maybe 3.5" system with Ecutec ECU.

:confused: :confused:
 

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Hi mate, if you take off the HKS fitted to your car and measure the flanges you will find that it is only 2.75 inches as they are pinched at the joints.
The Milltek is 3inch all the way through with beautifully welded flanges, external quality is not quite as good as some of the jap stuff, I thought the APS looked a touch flimsy myself and certainly looks odd coming out at an angle. My car made 17 bhp more with the Milltek on than the standard FQ300 HKS system, thats why I bought one and ended up selling them.
Also as one final big difference the HKS system is not stainless right through and does go rusty very quickly at the joints I reckon 2 years all weather driving would see it out.
Its true that the turbo elbow is a restriction, but the exhaust does still make a difference,why not change both ;) You can sell what you already have on Ebay and recoup a good % of the cost.
I happen to know that Millteks are £695 fitted or delivered. Hope this helps.
 

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Discussion Starter · #7 ·
Cheers Lightly for the info.

This is a part of the reason why my Magnex 3" downpipe has been lying on my garage floor for a week, because (a) I'm contemplating changing / porting the turbo elbow and (b) I'm also contemplating replacing the exhaust system from the de-cat pipe back.

With regards to the APS exhaust, I must admit that personally I think the angle of the tailpipe out of the rear bumper, makes the exhaust system look cheap :eek: In a sort of Scooby type way :rolleyes:
 

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guys we ran 2 evo 8 MR cars on the dyno with exactly the same spec apart from APS 31/2 exhaust . the other car ran a stock turbo elbow and a full magnex and a 21/2 decat silencer .

both cars had identical maps

which car made most HP ??

and why ?


dave
 

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Discussion Starter · #10 ·
evo400 said:
guys we ran 2 evo 8 MR cars on the dyno with exactly the same spec apart from APS 31/2 exhaust . the other car ran a stock turbo elbow and a full magnex and a 21/2 decat silencer .

both cars had identical maps

which car made most HP ??

and why ?
dave
Dave, that is the exact question. Why do APS for example make a 3" system and a 3.5" system?

What performance gains am I getting for my half inch :blush:

So what were the bhp/torque differences Dave. :p
 

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Hi guys just thought id add my bit,i always ask whats customers what they are planning to do with there cars first,if its modded already or not ect ect.Having a 3" exhaust over a 3.5" will yeild very little probably around 5bhp tops on a near standard car it certainly wouldn't be worth spending even more cash to swap from 3" to 3.5" the thing that most people miss is that cars have to be driven on the road and the roads are **** most the time,so the bigger the exhaust the lower its going to hang so the more speed humps ect your going to catch.
Also yes the turbo outlet is important theres no point putting a 3" zorst on if your outlet is 2.5" also check that its a proper sized zorst,look at the flanges on the ends usually the pipe decreases in size to near standard so that it can meet up to a standard system ect!
 

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Dave,

The car with the 3" exhaust made more power (guessing 10bhp) because of higher gas speeds in the smaller pipe.

Of course I could be talking horse sh!t...in which case...how much is the 3.5" system :-D


EDIT: Have I just won a new EVO400 turbo???? :) :)
 

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yes i had same arguement a few months ago on here,were we had seen cars make more power with smaller exhausts than bigger ones!
It really is down to the tune of the vehicle ect as to what will help increase power,i always advise to stay within reason on the zorst size.
bigger sometimes doesn't mean better!(not that the wife agrees)
 

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Discussion Starter · #14 ·
So are we saying, that unless your running a car with big performance, you don't need an exhaust with more than 3" internal diameter?

I'm just struggling to see the advantages of a 3.5" system over a 3" system?

I think the majority of us who want more performance out of our Evo's would generally like between 350 to 400bhp with matching torque, based on cars that have been modded at dyno days. :confused:

Obviously there's the like of T27, evotoo, isty etc that are in a different league :cool:
 

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I think what we are saying is that the car has to be considered as a whole entity. Changing one component effects another and so on.

The exhaust should be matched to the flow requirements of the engine. Sticking the largest one you can find on maybe fine on something like a Nova but on an Evo using too large a bore could effect performance.

Dave, would be interested to see the rolling road graphs of the two cars if you have them?
 

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BHP said:
With regards to the APS exhaust, I must admit that personally I think the angle of the tailpipe out of the rear bumper, makes the exhaust system look cheap :eek: In a sort of Scooby type way :rolleyes:
It's the 3.5" APS that comes out at an angle; the 3" APS comes out straight like the HKS Super Drager - it just has a slightly smaller opening.
 

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Discussion Starter · #17 ·
Radar said:
It's the 3.5" APS that comes out at an angle; the 3" APS comes out straight like the HKS Super Drager - it just has a slightly smaller opening.
Well I didn't know that Radar :eek:

I think every Evo that I have seen must have the 3.5 system fitted then :cool:
 

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the car with the smaller exhaust made more torque and 3 hp more . must admit i took a step back to look @ the results . we also plotted a stock mr with just a ecutek against a evo400 car vs time and you should see the differance . once again what do you think came out on top ????
 
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