Best Exhaust Manifold Design for Evo 4-9?

[teo1957]

1. Symmetric V-Shaped to Turbine & External Wastegate
Internal wastegate/actuator will release air at a maximum of how much boost pressure? 0.8, 1.2 bar? An option to increase boost levels is to use external wastegate. Symmetric V-shaped improves exhaust air flow to external wastegate, and promotes more accurate functioning of the wastegate.
http://www.turbosmartdirect.com/install/Ultragate.pdf

2. Tubular Steel
DSport magazine reported 20 horsepower and 15lb-ft of torque increase and better performance at all levels of the powerband (low end, midrange and top end) after they swapped a cast iron manifold with a unit made of tubular steel.
http://www.dragsport.com/issue/12/feat_article.shtml

3. Equal Length
Theoritically, can result in more consistent exhaust pulses going into the turbine.
http://www.dragsport.com/issue/12/feat_article.shtml

4. Short
Longer runners tend to lose too much energy through heat loss.
http://www.dragsport.com/issue/12/feat_article.shtml

5. Ceramic Coated
Also prevents energy loss for the exhaust gases, and perhaps more importantly, keeps engine temperature low. This is because the Evo exhaust manifold is located directly behind the radiator, and can help to boil the water inside the radiator.

Can I buy an exhaust manifold which possesses all these ideals for under RM1k?

 

[SDF]

theories are aplenty and each has it's merits based on the user's point of use.

for example :
Drag purpose , you'd be looking at large inner diameters coupled with long runners due to high boost and lots of exhaust pulses.

Track purpose, you'd be looking at something in relative to pair with the turbo of your choice. Choice of fuel and etc...

Street usage , again depends on choice of turbo and etc...

BUT the most important is...can your fabricator get it to as close to what is recommended..it's not easy to get equal runners and if you're gonna get it done locally, ensure the welder know's his job and know how to debur and clean it up properly. We've seen many turbos sent to the grave due to shoddy jobs on exhaust manifolds.

good luck~

 

[cmng]

pasal itu.. pakai balik stock manifold lagi baik
tahan lasak

and in english
that reason.. use back stock manifold even betten
long lasting

 

[jinkl]

pasal itu.. pakai balik stock manifold lagi baik
tahan lasak

and in english
that reason.. use back stock manifold even betten
long lasting

wawawawa u all lucky :( most nissan already with t25 and t3 flange manifold

 

[teo1957]

for example :
Drag purpose , you'd be looking at large inner diameters coupled with long runners due to high boost and lots of exhaust pulses.

Yes bro, I totally can understand the justification. We want exhaust pulses to enter the turbine fast enough, not too fast.

BUT the most important is...can your fabricator get it to as close to what is recommended..

The exact reason why I seek help from somebody who care to shed some light and point me to the right direction/fabricator.

Example: Evo 4-9 intercoolers sit low, and the piping to the throttle move upwards almost in a 90 degree angle. That's hell of a lot of energy to lose moving the air upwards. To compensate for the energy loss, a wide-narrow-wide diameter piping going upwards might be required. Now most of the fabricators tend to use bigger piping. Mention about energy loss, and the fabricator will start boasting "I done many Evos, win many races" and other customers will start to look at you like you're lansi.

and in english
that reason.. use back stock manifold even betten
long lasting

I don't know about Nissans, but in Evos, cast iron manifolds are used, which are:
1. heavy;
2. can't be welded upon by most fabricators, except industrial fabricators;
3. proven 20hp gain when replaced with tubular steel manifolds.

 

[speed2horizon]

Well there are limitation when u are trying to apply theory into application. Well, Example,

1) tubular exhaust manifold. Stainless steel seems nice, but how many fabricator uses thick elbow and chamfer the edges of the tubes before they weld in order to increase the strength of the joint. It's also not easy to achieve equal length unless u extend length of the single pipe before the flange.

2) It's not easy to achieve Y joint on wastegate and turbo. Unless u wanna locate ur wastegate down which is hardly visible. And also, it's hard to reach when modification, maintenance is necessary.

 

[SDF]

i'd say..it's all up to what you really want, then i'm sure forumners in here would be kind enough to point you in some directions.. what we're doing now is shooting straight into the air..