from the group by which is 2.5"? And will there be any benefit in going to only 2.25" front and dump pipes?, seeing as they are already around that mark by my lame ass measurements. I was thinking all 2.5" but it seems dump and front pipes usually come in 2.25" thanks sam
They should match up.....>> as they are both designed to fit to the rest of a standard system. You can get 2.5" dumps if you look, although it probably isn't a problem going from a 2.25" to a 2.5" pipe half way along the system
did you get a noticable or measured power increase from them? and is the fact that they're only 2.25" holding your numbers back at all from what you were expecting, or are your numbers comparable to others with full exhaust and whatever other mods you have? sorry for all the questions it just doesn't seem right to have smaller pipes at the front of the system when, on the stock system, this was the biggest part. Also do you get flames out the back of the exhaust because you don't run with cats? That would be bad.
Yeah very noticeable gains. And the dump pipes open up a lot of High end (up high in the revs)power, feels like it any way. Alot more mid band torque too. Both my 02's were dead and I changed them for new ones, so that could also be contributing to why my car feels a lot more responsive and faster. I also don't have the wastage separator bits in, as they don't fit, bad machining, seems its just me though that got the bad ones. I haven't had access to a machine to grind them down, so for now they are out, I am sure I will get a little bit more having them in. before I was making 340odd RWHP with stock dumps and 3" system, I feel I am making more now. I have seen flames out the back of my zed, at night time, but bov's play a crucial role in that, it doesn't flame all the time, I have to be pushing it really hard and get the bov's to go for it to *some times* hardly ever shoot a flame. Also, if its such a worry, you can get cats put into the test pipes.
nah that's cool i don't mind if it flames a little bit occasionally, but i don't want to be driving around having people think i have one of those bloody flame thrower kits in my car - already cop enough at work from the ford/ holden owners about my car being a hairdressers car. Of course their cars are all slower, so they're jealous, but still.
Yeah 2nd that one definate noticable gains! Much more response and torquier down low - definately not a placebo effect!
In my opinion... The gains from 2.25" to 2.5" are not huge. In fact, our Tune Agent pipes are closer to 2.3", not that it makes much difference at the end of the day. You've got two of these things remember, not one. On single turbo cars, you go for a 3" exhaust and it's considered a large performance exhaust. On the other hand, you go for 2.25" on the Z set, and you get 2 x 2.25" worth of area. Here's the sums: 2.25" dual = (pi*((2.25/2)^2))*2 = 7.9521563953125 3" single = pi*((3.0/2)^2) = 7.06858346250 (in square inches). So, you've got more area in your exhaust than that of a guy in a silvia running around with his 3" performance exhaust.
I don't get it, hairdresser car? I only know one stereotype associated w/ hairdressers (male ones at any rate), but I can't see carson from queer eye boosting around in a zed somehow. Someone care to elucidate?
Not quite true At least not the way I understand it anyway. Pipes provide laminar flow because of the effect of friction on the inner surface. Kind of like a river is fastest in its middle rather than along the bank. Hence actual flow of exhaust is fastest in the centre and slower at the edges affecting the volume of gas expelled over any time. The circumference of a 3" exhaust is 9.4" and 2 times 2.25" is 14.1" (rounded). So the surface area is actually a lot larger in the twin setup. You benefit from more area to your exhaust but its not quite as simple as just comparing the two areas in question as the one with more inner surface area will have more friction and more back pressure on the turbos.
zisluv is on the ball, it's not simple multiplication to work out the difference, i could pull out the theory, but that's a whole lot of looking which isn't going to happen. I think 2x2.25 would work out to around the equivalent of a 3.5" single system. But that really doesn't matter, it's more important to determine what size is adequate for a 1.5 L 3 cyl turbocharged engine, as that is really the more important consideration. Also, my issue is not necessarily that 2x 2.25" is inadequate, but more the fact that moving to a larger pipe size without using some sort of decent reducer (two flanges bolted together at different sizes give poor flow characteristics) will create poorer performance from the system than using 2.25" the whole way through. As the exhaust flows through there will be a low pressure formed as indicated by the 'L' in the diagram below. As the (relatively) higher pressure flows past this low pressure it will be directed to the lower pressure area (pressure gradient force). This will form turbulent eddies that break away from the laminar flow of the main exhaust stream (the outer part of the exhaust is usually turbulent where the laminar flow meets the boundary layer anyway, but much more of the flow will become turbulent in this case). The exhaust will also be slowed as it is moved into the larger piping. This is also detrimental to optimum flow as the objective is to keep the air hot and fast in the exhaust so it stays sparse and moves quickly from the exhaust. Any densening of the gas due to cooling will disrupt the flow of the exhaust more. The tubulent flow near the walls of the pipe is also the reason for the two pipes not adding up to one larger pipe of the same resultant cross sectional area - the more turbulent flow, the less efficient the exhaust system.
the guys call it a hairdressers car cause it looks nice much like a hairdresser . Nah seriously I think it just irks the V8 crew that a Turbo 6 around work gets probably more attention from the finer sex and is also faster than their cars. Doesn't help reassure them about their penis extensions at all.
Indeed What I posted certainly wasn't untrue. The cross sectional area of the twin 2.25" is larger than a single 3". I never mentioned anything about flow dynamics or anything like that because most people (including myself) don't understand them well. All I was really trying to point out is that some people don't quite realise that in actual fact the amount of exhaust flow capacity their twin Z system has can't be compared in diameter to that of a single system in terms of performance. People tend to think that they should get a 3" system on the Z, which is just extremely large. The flow characteristics may actually result in the car making less power, because of the loss in back pressure. Use the right tool for the right job. If you're planning on making a thousand or so horsepower, I'd start looking at bigger systems. Generally on single system cars if you're going for those numbers you look for a 4" or more system. So on the Z you might look at a twin 3" to suit.
IT wasnt just you who got problems, with these dumps.Mine were stopping the wastgate from opening,(passenger side) moveing the seperator a little didnt help, it was also a little long, which caused it to seat on the turbo body. Had it ground, all good now! ,
