I'm with shabby on this one. The thermal cycling, vibration, and turbocharger weight conspire to always kill thin-wall tubular turbo manifolds in street applications.
Even on race cars, tubular manifolds are considered temporary. Back in the day, when F1 cars were turbocharged, the engineers insisted on thinwall tubular headers so as to impart the greatest exhaust heat energy to the turbine, thus achieving optimal response time off corners. Lifespan of one tubular header set? One race.
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Bill Hahn Jr., Hahn RaceCraft, Inc. Home of the World's Quickest and Most Powerful Solstices
First to the 14's, 13's, and 12's in the 1/4 Mile
12.00 @ 117 MPH Street Solstice World Record
Hahn RaceCraft, Inc.
Turbocharging GM's since 1988 http://www.turbosystem.com
I'm with shabby on this one. The thermal cycling, vibration, and turbocharger weight conspire to always kill thin-wall tubular turbo manifolds in street applications.
Even on race cars, tubular manifolds are considered temporary. Back in the day, when F1 cars were turbocharged, the engineers insisted on thinwall tubular headers so as to impart the greatest exhaust heat energy to the turbine, thus achieving optimal response time off corners. Lifespan of one tubular header set? One race.
So are you recommending staying with the "bar" style OEM manifold? I'm new to Turbocharging applications and had been looking for an upgrade in this department after reading a few books on the subject.
So are you recommending staying with the "bar" style OEM manifold? I'm new to Turbocharging applications and had been looking for an upgrade in this department after reading a few books on the subject.
It's really a cast header, for all intents and purposes. It's not a log-type in that there are discrete cylinder runners. It's a decent piece, and I feel it can support 500-600 HP before it gets to be a big restriction.
__________________
Bill Hahn Jr., Hahn RaceCraft, Inc. Home of the World's Quickest and Most Powerful Solstices
First to the 14's, 13's, and 12's in the 1/4 Mile
12.00 @ 117 MPH Street Solstice World Record
Hahn RaceCraft, Inc.
Turbocharging GM's since 1988 http://www.turbosystem.com
The problem with that manifold is, the primary size might be larger, but honestly that usually isn't the biggest power maker, primarily, its runner length which can yeild drastic effects on power.
That is simply too short to take advantage of any useable resonance tuning, as is the stock manifold.
The stock on was looking for 4 things.
Cheap
Fast Spool
Keep pulses separated
Reliable.
If you found a thin walled tubular with say 14 inch runners, I'd run that no problem. And buy a back up :}
It could be done, but would be a mess in there. Truth be told for this rpm range more like 24-28" primary might be ideal. Lots of heat entrophy with that much area.
I'm totally in Bill's camp on this one. Lots of power to be made before a change in primary area / runner length is absolutely nessicary.
Didn't Sheperd Run a cast manifold into the 8's on his dsm?
Doesnt Wheel to wheel have a racecar that uses 6.0 truck manifolds with a 106mm turbo?
I suspect when the inlet of the turbo exceeds 66mm in dia, you have duration that is >240@0.050" and principle RPM band starts around 4K, the few odd bends & area of the stock manifold will make it worth ditching. Sounds like Fun.
If you Really want a thin wall header that will last? I'll build you one from inconel 625. The cost of u-bends might make you hork . Pop over to burns stainless's site.
Last edited by BaldTurboFreak : 07-11-2008 at 07:33 AM.
I know how to design for resonance tuning. You're suggesting first pulse tuning, which is retarded for a high rpm machine, yes you get stronger resonance tuning, but its on a shorter window and will cause other adverse effects when you tune for first pulse for top end.
So, the numbers I've quoted give a broader but less peaky second resonance pulse tuning at the same RPM roughly you are looking at, and it would be easier fitment.
6350rpm is high? lol. I shoulda been more clear, my fault bud.
Engine combo #2 (the suggested reason for leaving the stocker on the shelf) would align itself well with your second pulse tuning.
Heck were both a little off anywho, as the wave's velocity increases as gas density goes up. Not very easy to model at all.
If Im not mistaken,as TIP packs up the pressure wave will travel faster thru the column of gas (fluid). this will make a longer runner behave as a shorter one. So thru much testing it seems it would be possible to get strong 1st pulse resonsant tuning in the low band where the turbo is lazy and TIP is low. then as the turbine wheel's up and turbine pressure (gas density) begins to climb the long runner contuinues to deliver strong resonant effect in a higher band due to the pressure and scavenge wave's increased velocity.
It can get even more fun with a carefully sized compressor/turbine combo. For a usually small window you have the TIP/MIP cross. Crazy mass flow during overlap.
I don't have time at the moment to reply BTF, but Lithium, but no a port match would be a poor idea, until you totally retimed all of the cam control, you will at times have high overlap, and typically everyone wants fast spool so the housing will be restrictive, which would = reversion, big time.
. Pop over to burns stainless's site.
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