i make what the customer wants. he said "i want a uel header". so thats what i give him. if it were me, i stick to twinscroll or at the vary least 1.5 scroll
Nice work - and UEL is the only way to go, unless you want to sound like every other 4banger on the planet...
or if you want real gains from a header. taking a power loss for a sound is silly in my book. but to each there own...
And destroying a perfectly good 04 STi so it can collect dust for years and years until its finished, and then possibly get driven once down a track may seem like an awful waste to others on here.
I'm not saying... just saying. I personally think it will be very cool to see that thing go down the track eventually. I plan on being there when it does for the first time, actually. But I know there are talkers......... :hsugh:
thats one way of looking at it i guess but i bought my car knowing it will be a project car. never once was it suppose to be a dd in the slightest way. with that said working on it little by little doesn't bother me tell i have the time to dedicate to it after i get these other cars done. i had people saying that same thing when i started the first build too... some people cant think past a 20g....
Id settle for one right now if you wanna give me one I need to come over and hang out again with you guys...
this saterday sounds like car day if you want to come over? have to make a ewg up, weld a intercooler pipe set for a vw and finish dips and riches ewg flanges. should be filled with car fun!
Twin scroll manifold vs. unequal length is pretty well documented and easy enough to find that it isn't even worthy of an argument.
One of the biggest limitations of most factory single-scroll turbo system is the restrictive nature of its log or compact unequal-length exhaust manifold. Keep in mind, the purpose of this manifold isn't just to channel exhaust gases to the turbocharger's turbine wheel; the manifold must be designed to allow exhaust gases to exit the combustion chamber of each cylinder quickly and efficiently. Also keep in mind that these exhaust gases do not flow in a smooth stream because the gas exits each cylinder based on the engine's firing sequence, resulting in distinct exhaust gas pulses. Next time you fire up your car, place your hand lightly over the exhaust tip (before it gets hot!) and you will feel these pulses. With a log-style or compact OE-style, unequal-length runner exhaust manifold like you'll find on SR20DET or USDM STI engines, the pulse from one cylinder can interfere with subsequent exhaust gas pulses as they enter the manifold from the other cylinders, inhibiting scavenging (where the high-pressure pulse draws the lower pressure gases behind it out of the combustion chamber with it) and increasing reversion (where exhaust gas flow is disturbed so much that its direction of travel reverses and pollutes the combustion chambers with hot exhaust gases). The trapped and wasted kinetic exhaust gas energy from poor scavenging and too much reversion also means higher combustion and exhaust gas temperatures, necessitating less aggressive ignition timing and reduced valve overlap as well as richer air/fuel mixtures (and higher NOx emissions).
Dippy, you should quote that. The factory exhaust manifold isn't horribly inefficient like that statement suggests. The collectors do a decent job of merging the cylinders in a smooth fashion. However, a twin scroll setup does a better job of keeping the exhaust pulses separated from other cylinders which may open their exhaust valves around the time of others. Also, the equal length nature of a TS manifold makes the pulses hit the turbine in an even fashion, making better use of the exhaust energy. Factory pattern hitting the turbine: .. .. .. .. .. TS pattern: . . . . . . . . . . . . . . Large turbos realize more of a gain from a twin scroll setup due to the much larger amount of energy required to spool the turbine. People do make big power on the factory manifold though. A couple people here have crept up to the 500whp mark with an OEM manifold. A TS manifold would give them a broader power band though, and probably more power up top.
Nice looking parts.... I can understand why people don't want to give up the Subaru sound especially when you can still make good power with UEL. I'd rather have a 300hp flat plane crank V8 over a 500hp cross plane V8 for instance. To each their own... 8)
