stepped headers

[Celica RA45]

has any 1 seen any web pages that talk about 4 into 1 stepped headers at all thinking of going to the dark side

[AJPS]

People need more info glen!

[70XIN]

I wondered if anyone would ever bring this up



*sorry for the big picture guys, but you wouldn't really notice the 'step' without it this big*

JSPfab in the US has been making all kinds of 4A/F20C/etc headers for a while, has remade the genuine TRD headers etc etc. His new lot of headers are stepped, and have made more power than any of his previous headers. I really haven't read much on the web that's very helpful, it seems most people keep their info close to their chests *waves fist around*.

http://www.jspfab.com/catalog/i63.html

[Celica RA45]

well i have been trying 4 into 1on the dyno with slip joints and have made more power and torque than the trd pipes but the hp justs flattens off at 7600 and its still making the same power at 9000

[Frak]

Do a search I have some dyno runs done on an ST using std headers then stepped headers, they were 4-2-1's but were stepped primary pipes.

[lolwat]

those headers are the SEX!

[khoala]

jesus those are a work of art! but i heard they're only worth it if you're running huge cams as you'd lose torque in the low/midrange with stock or mild cams?

[xero]

I wondered if anyone would ever bring this up



*sorry for the big picture guys, but you wouldn't really notice the 'step' without it this big*

JSPfab in the US has been making all kinds of 4A/F20C/etc headers for a while, has remade the genuine TRD headers etc etc. His new lot of headers are stepped, and have made more power than any of his previous headers. I really haven't read much on the web that's very helpful, it seems most people keep their info close to their chests *waves fist around*.

http://www.jspfab.com/catalog/i63.html

when i was looking at them john was saying that for the first section they are 1.5" then step up to 1.75" with a 2" collector and then a 2.25" pipe off that.
they are basically the same style and shape they were running on the formula atlantic cars.

the stepped headers im sure would provide that extra little of flow up top, but the hardest thing i reckon would working out where to enlarge to the next step and how big to make it.
i agree toxin a lot of people hoard that sort of information, and again looking at websites reading info you can sort of only get bits and peices which you then have to put into some sort of order. i can understand that if your trying to get the edge over the guy next to you, but if your no longer racing or involved people should really share what they have learned.

[Gunner]

when i was looking at them john was saying that for the first section they are 1.5" then step up to 1.75" with a 2" collector and then a 2.25" pipe off that.
they are basically the same style and shape they were running on the formula atlantic cars.

the stepped headers im sure would provide that extra little of flow up top, but the hardest thing i reckon would working out where to enlarge to the next step and how big to make it.
i agree toxin a lot of people hoard that sort of information, and again looking at websites reading info you can sort of only get bits and peices which you then have to put into some sort of order. i can understand that if your trying to get the edge over the guy next to you, but if your no longer racing or involved people should really share what they have learned.

From what I have been told by the "older" generation, they use a mix or pyro's and pressure measurements. One particular oldie, explained how its all about gas expansion, and by measuring the exhaust gas pressure, and temps, you can calculate where the gas slows down and causes the restriction, in turn by flaring or expanding the pipe, you can allow gas velocity to remain constant, as it cools on its way through the exhaust system. How true, I don't know, as xero said old school racers don't like giving up much info.

[xero]

yeah, when i had my exhaust done recently i was discussing this with the owner of the shop. he was saying that as the gasses cool down and increase in desity you step up the next 0.25" IE 2.25 at the collector, stepped up to 2.5" after the cat, until the rear muffler. he was saying this is good for constant flow but ends up with a really boomy and blaring exhaust (think FWD lancer/pulsar/corolla/civic with a cannon muffler) and is not fun on the street. race car no worries as its usually just a straight through pipe, street car usually leaves you deaf after driving it.

the calculations idea is a good one, except im a bit slow in the maths dept. so it would have to worked out the hard way. i forgot to mention the 1.5" section was for the first 10-12" (250-300mm) and 1.75" section length was around the 12-16" length (300-400mm) then into the collector.
rough sizing didnt have them physcally much bigger than the TRD copies, but with a bit more work into them.

just going off the top of my head i would say running a 1.5" primary for 400mm them stepped up to 1.75" for the remainder 500-600mm with a 2.5" collector should make bulk power at the top, whilst still providing low end pressure and torque. i reckon by the time the exhaust gases are halfway down they would be losing their temp and would need to expand some where, also the actual length of the primaries would play a part as well. long primaries would reduce heat quite quickly as they would have much much greater surface area than if you ran shorter ones, and as such the longer the headers the faster the gases would be moving by the time they hit the exhaust system itself so would necessitate a step up into the main exhaust pipe.

well at least that make sense in my head..