The Top DSM Community on the Web

For 1990-1999 Mitsubishi Eclipse, Eagle Talon, Plymouth Laser, and Galant VR-4 Owners. Log in to remove most ads.

  • Join the Community!

    DSMtuners is a massive archive of DSM information - but more importantly, it's a COMMUNITY! Join in and participate with other DSMers, and invite all of your DSM friends to make this place their home. Chat with others, create a build thread, post questions and answers. Get involved! Logging in will also remove many of the advertisements, along with this notice. ;) It will also allow you to view images in threads.

Please Support JNZ Tuning
Please Support STM Tuned

Twin scroll hx35 spool results.

boostdawd

Supporting Member
1,450
326
Apr 6, 2010
phoenix, Arizona
In regurds to @bastarddsm saying 1.5" primaries are too big for 95% I'd have to disagree in a way, this also depends on what material thickness your manifold is. I'll agree 1.75" is way way huge unless your running above a 72mm but most all manifold manifacturers use 1.5" sch pipe weld els, now here is the difference, sch10 has a larger ID than sch40 by a couple mm, so although thicker, the sch40 will have more velocity then it's sch10 counterpart of the same design. A lot of the main shops use sch10 because it is cheaper. But the sch40 manifolds seem to perform much better. Just something to think about.
What type do u use on your masterpieces?
 

lasthope05

Proven Member
1,158
266
Mar 31, 2006
Philadelphia, Pennsylvania
Im more inclined to believe smaller, 1.25", runners are more ideal for small/mid framed turbo. The smaller runners will definitely help increased exhaust gas velocity and spool times without limiting overall exhaust flow up to a certain point. I believe there are diminishing gains with manifold pipe size as there is with exhaust systems. Being able to tailor that one part for you application is hard because, like you, many manufacturers just stick to the standard 1.5 els.

Ron Shearer offers a small diameter 1.25" manifold for our cars. His prices are higher than most but he actually has lots of testings and data on his products.
 

bastarddsm

Proven Member
5,345
1,150
Aug 26, 2003
Mendota, Illinois
In regurds to @bastarddsm saying 1.5" primaries are too big for 95% I'd have to disagree in a way, this also depends on what material thickness your manifold is. I'll agree 1.75" is way way huge unless your running above a 72mm but most all manifold manifacturers use 1.5" sch pipe weld els, now here is the difference, sch10 has a larger ID than sch40 by a couple mm, so although thicker, the sch40 will have more velocity then it's sch10 counterpart of the same design. A lot of the main shops use sch10 because it is cheaper. But the sch40 manifolds seem to perform much better. Just something to think about.

What has lead you to this conclusion? When I made this statement I was referring to 1.25 and 1.5" schd 10 I believe. I still stand by this, and my argument comes from a thorough survey of the field, as well as both simple geometrical calculations, and complex thermo-fluid science simulations.

If you do some searching on the right forums you'll see that buschur and shearer have worked together on some header testing. As best as I can tell, buschur is about the most thorough and fair person you will see dyno testing parts. They found small primaries, around the size of 1.25 sched 10 was good for a 200rpm improvement in spool over 1.5, and it did not show any power loss on a 35r setup making 600whp on bushcher's dyno. That's more than 95% of dsm'ers will ever make. Next they turned up the boost and made like 675, the small runner didn't cost power, but buscher thought it was unhappy or something, as the curve was lumpy. Perhaps playing with cam timing could have fixed that.

If you look at any real race car, the headers are made from 321 mandrel bends not pipe fittings, and the primary's are smaller than 1.5" schd 10 or 40. That abrupt transition from the oval port to round that everyone does on a dsm/evo header is garbage too. The only thing worse is the sharp 90* that a top mount header has there, plus the 6' of tubing they have to loose all that exhaust energy.
 

Devilsfutbol17

Proven Member
399
24
Jul 27, 2007
Bellingham, Washington
Does this come into play with manifold construction? It looks like it could make a difference to me. Found this video on facebook. I tested my T3 TS manifold and it did not pass this test.

You must be logged in to view this image or video.
 

Archer Fabrications

Proven Member
9,976
977
May 9, 2011
Scottsdale, Arizona
What has lead you to this conclusion? When I made this statement I was referring to 1.25 and 1.5" schd 10 I believe. I still stand by this, and my argument comes from a thorough survey of the field, as well as both simple geometrical calculations, and complex thermo-fluid science simulations.

If you do some searching on the right forums you'll see that buschur and shearer have worked together on some header testing. As best as I can tell, buschur is about the most thorough and fair person you will see dyno testing parts. They found small primaries, around the size of 1.25 sched 10 was good for a 200rpm improvement in spool over 1.5, and it did not show any power loss on a 35r setup making 600whp on bushcher's dyno. That's more than 95% of dsm'ers will ever make. Next they turned up the boost and made like 675, the small runner didn't cost power, but buscher thought it was unhappy or something, as the curve was lumpy. Perhaps playing with cam timing could have fixed that.

If you look at any real race car, the headers are made from 321 mandrel bends not pipe fittings, and the primary's are smaller than 1.5" schd 10 or 40. That abrupt transition from the oval port to round that everyone does on a dsm/evo header is garbage too. The only thing worse is the sharp 90* that a top mount header has there, plus the 6' of tubing they have to loose all that exhaust energy.

My point is that a 1.5" sch40 will spool quicker then the 1.5" sch10. Because it has a smaller ID by a few MM, thus not needing to sacrifice FLOW of which a 1.25 would. The same thing applys to sch10 & sch40 in 1.25" in which case id say the sch10 varient is better for flow then its sch40 counterpart. I didn't say 1.25 was bad or that it cost power, it's just not as optimal as a 1.5" sch40 where you sort of get the best of both worlds, in my opinion. Each choice has it's place
 
Last edited:

ThunderChild

Supporting VIP
3,766
1,118
Jan 5, 2012
Rathdrum, Idaho
I'm out of most of this discussion, but the video caught my eye.

Does this come into play with manifold construction? It looks like it could make a difference to me. Found this video on facebook. I tested my T3 TS manifold and it did not pass this test.

This is a good example of a designed manifold with good collector angle. granted I want to express on a scavenging effect, but remember, we have turbines impeding flow to a certain point. at optimal flow, id expect this test to show some similar results in a practical test, but it mostly comes down to the cheap manifold collector design and ramming all the exhaust into a common area, vs directed flow to the collector and into the volute like the better made manifild.

Just an observation, but pretty easy to see the difference.
 
Last edited:

GSXftw

Proven Member
382
77
Dec 16, 2009
Medford, Oregon
I'm out of most of this discussion, but the video caught my eye.



This is a good example of a designed manifold with good collector angle. granted I want to express on a scavenging effect, but remember, we have turbines impeding flow to a certain point. at optimal flow, id expect this test to show some similar results in a practical test, but it mostly comes down to the cheap manifold collector design and ramming all the exhaust into a common area, vs directed flow to the collector and into the volute like the better made manifild.

Just an observation, but pretty easy to see the difference.
Thank you for this. Im researching to build my first TS mani and was wondering about this vid I had seen as well. I didn't know what the real difference was but the collector angles make total sense.
 

ErikTande

Supporting Member
1,426
415
Dec 17, 2012
Centennial, Colorado
Does this come into play with manifold construction? It looks like it could make a difference to me. Found this video on facebook. I tested my T3 TS manifold and it did not pass this test.

You must be logged in to view this image or video.

Can anyone explain the significance of this test? The pitch of the air changes on the first manifold which I would assume means the runners aren't all the same size. Which I assume is bad. I don't understand the vacuum on the second manifold.
 

GSXftw

Proven Member
382
77
Dec 16, 2009
Medford, Oregon
Can anyone explain the significance of this test? The pitch of the air changes on the first manifold which I would assume means the runners aren't all the same size. Which I assume is bad. I don't understand the vacuum on the second manifold.
They are the same size, it has to do with the collector and the angle they meet.
 

lasthope05

Proven Member
1,158
266
Mar 31, 2006
Philadelphia, Pennsylvania
Can anyone explain the significance of this test? The pitch of the air changes on the first manifold which I would assume means the runners aren't all the same size. Which I assume is bad. I don't understand the vacuum on the second manifold.

The test shows what a properly built TS manifold should do. The second manifold is built to where the flow of one runner scavenges exhaust flow from the other which helps with cylinder filling. The first manifold does the opposite where it causes reversion of the exhaust gases back up the runner. Thought I dont know how much this would effect a boosted car. Either way, I'll take a properly built scavenging manifold any day.
 

ThunderChild

Supporting VIP
3,766
1,118
Jan 5, 2012
Rathdrum, Idaho
More so, this type of design consideration is going to focus on maintaining velocity and helping guide (scavenge) the other exhaust pulses into the turbine housing, vs just ramming all the exhaust through any opening like so many factory and log manifolds do.

You should see reduced drive pressure/egts/spool times and better top end flow theoretically, but there are alot of other factors that play into that like: runner size/length, turbine housing size/type, tune, etc. Basically you are trying to increase flow potential and make your exhaust ports work in unison, vs fighting to get out first and causing a buildup of pressure.
 
Support Vendors who Support the DSM Community
Boosted Fabrication ECM Tuning ExtremePSI Feal Suspension Fuel Injector Clinic Jacks Transmissions JNZ Tuning Kiggly Racing Morrison Fabrications MyMitsubishiStore.com OHM Racing Raven Fabrication RixRacing RockAuto RTM Racing SouthBay Fuel Injectors STM Tuned VR Speed Factory

Latest posts

Build Thread Updates

Vendor Updates

Latest Classifieds

Top