Finally maybe an equal length header?!

[LynX853]

http://www.sacramento-mustang.com/cgi-bin/cart.pl?db|svo.dat|exhaust

yeah its expensive, but they have close to the same dimentions and space issues that we do... and now that FWD sells the flange kits, i say cut the ford flanges on, and on with the TD ones. or if you want to, you can run a turbocharger for a turbo ford... heck you can get hybrids for those things DIRT cheep! http://cgi.ebay.com/ebaymotors/T3-T4-hybrid-turbo-SVO-Turbocoupe-Turbo-Ford-5-BOLT_W0QQcmdZViewItemQQcategoryZ33742QQihZ019QQite mZ8071236510QQrdZ1

like SO! :thumb: i know that your gonna say its expenisve (the header) but it IS really well designed and you gotta pay to play. if it was up to me and i had to start all over again, id get a ford hybrid turbo, and that header.

im just trying to think outside the box here. LMK what you guys think

[WVRampage]

Well its not a equal length but it does look like a Idea for a header and clearence issues.

[BadAssPerformance]

Nice header, but it looks like it might have some intake manifold clearance issues.

http://www.sacramento-mustang.com/images/svo_7300.jpg

[Whorse]

Is the spacing close enough between the two engines' head ports?

[turbovanman²]

I guess the obvious hasn't been stated, the header flange is totally wrong. Stephane made some of those for around the same price but everyone bitched and no one bought any. That turbo you linked to is junk, figure on it lasting 1-2 weeks, if your lucky.

[LynX853]

ok, like i stated before, you would have to cut the old flanges off and weld TD ones on... (FWD now offers them) I didnt realize that those turbos were bad

[LynX853]

and if that header doesnt work, do a search on svo 2.3 turbo headers on google. some have different designs ect.

[Clay]

why is the turbo junk?

[puppet]

The more you read about equal length headers and turbocharged engines the more it seems not to matter until your making huge HP. There are some better log designs out there that for 90% of us would be more than enough. A product like this is where it's at.
http://www.revhard.com/turbomanifold/cast.asp#H22TurboManifold
Check out "H22 Turbo Manifold" on that page. Something like that might be pretty damn good for us.

The space problems, the additional effort and cash involved in making equal length work for the little gain doesn't seem worth it to me.

[BadAssPerformance]

The more you read about equal length headers and turbocharged engines the more it seems not to matter until your making huge HP. There are some better log designs out there that for 90% of us would be more than enough. A product like this is where it's at.

The space problems, the additional effort and cash involved in making equal length work for the little gain doesn't seem worth it to me.

I'm interested in reading about this. Got a links to any tech papers? Specifically from technical sources, not people trying to sell log type manifold headers?

[puppet]

http://www.google.com/search?hl=en&lr=&client=firefox-a&rls=org.mozilla%3Aen-US%3Aofficial_s&q=ducted+log+exhaust+manifold+turbocharged+engine&btnG=Search
http://www.google.com/search?q=curing+reversion+turbo+log+exhaust+manifo ld&btnG=Search&hl=en&lr=&client=firefox-a&rls=org.mozilla%3Aen-US%3Aofficial_s
http://www.google.com/search?q=designing+divided+turbo+exhaust+manifold+ inline+four+cylinder&hl=en&lr=&client=firefox-a&rls=org.mozilla:en-US:official_s&start=170&sa=N
http://www.google.com/search?hl=en&lr=&client=firefox-a&rls=org.mozilla%3Aen-US%3Aofficial_s&q=ducted+log+exhaust+manifold+turbocharged+engine&btnG=Search
http://www.google.com/search?q=ducted+log+manifold+turbocharged+engine&hl=en&lr=&client=firefox-a&rls=org.mozilla:en-US:official_s&start=20&sa=N
http://www.google.com/search?q=ducted+log+turbo+exhaust+manifold&hl=en&lr=&client=firefox-a&rls=org.mozilla:en-US:official_s&start=80&sa=N
http://www.google.com/search?client=firefox-a&rls=org.mozilla%3Aen-US%3Aofficial_s&hl=en&q=equal+length+manifold+what+distance+does+it+matt er&btnG=Google+Search
http://www.google.com/search?q=fabricating+a+pulse+manifold&btnG=Search&hl=en&lr=&client=firefox-a&rls=org.mozilla%3Aen-US%3Aofficial_s
http://www.google.com/search?q=fabricating+a+pulse+turbo+exhaust+manifol d&btnG=Search&hl=en&lr=&client=firefox-a&rls=org.mozilla%3Aen-US%3Aofficial_s
http://www.google.com/search?q=fabricating+inline+four+pulse+turbo+exhau st+manifold&hl=en&lr=&client=firefox-a&rls=org.mozilla:en-US:official_s&start=20&sa=N
http://www.google.com/search?q=internally+ducted+log+exhaust+manifold&hl=en&lr=&client=firefox-a&rls=org.mozilla:en-US:official_s&start=10&sa=N
http://www.google.com/search?q=managing+reversion+turbo+log+exhaust+mani fold&hl=en&lr=&client=firefox-a&rls=org.mozilla:en-US:official_s&start=20&sa=N
http://www.google.com/search?q=proper+cylinder+pairing+divided+exhaust+m anifold+runners+inline+four+turbo++&hl=en&lr=&client=firefox-a&rls=org.mozilla:en-US:official_s&start=50&sa=N
http://www.google.com/search?q=proper+cylinder+pairing+inline+four+turbo +exhaust+manifold+runners+turbo&hl=en&lr=&client=firefox-a&rls=org.mozilla:en-US:official_s&start=10&sa=N
http://www.google.com/search?q=proper+pairing+inline+four+cylinder+exhau st+manifold+runners+turbo+header&btnG=Search&hs=Vy7&hl=en&lr=&client=firefox-a&rls=org.mozilla%3Aen-US%3Aofficial_s
http://www.google.com/search?q=pulse++exhaust+manifold&hl=en&lr=&client=firefox-a&rls=org.mozilla:en-US:official_s&start=20&sa=N
http://www.google.com/search?q=pulse+exhaust+manifold+turbo&hl=en&lr=&client=firefox-a&rls=org.mozilla:en-US:official_s&start=30&sa=N
http://www.google.com/search?hl=en&lr=&client=firefox-a&rls=org.mozilla%3Aen-US%3Aofficial_s&q=+reversion+turbo+log+exhaust+manifold&btnG=Search

... been a googlin' fool for a week or so.

The searches turn up many articles an .pdf's on the suject ... some junk on both sides of the debate.
http://www.team-integra.net/forum/display_topic_threads.asp?ThreadPage=1&ForumID=12&TopicID=77064
This was a good read. Some articles from Max Boost are online as well.
There is no doubt that the equal length is good. Just "how much" is the debate. For instance the reversion issue often brought up can be minimized with choice of cam profile. That makes the log type manifold no so bad after all.

Just the difference in the buzz words like "pulse", "pressure", "tri Y", "equal length", log", "long tube", short tube", "large cross section", "narrow cross section", "shock waves", "reversion", "heat loss", "pressure loss" .. all make for different designs schemes. All of them can work on any given engine. What sets them apart is where they produce the power. This in itself can drive a guy nuts. ... let alone tring to make it all fit.

A well designed log mani will spread the power out over a wider rpm range and scavange the exhaust fine as well. More so than a application specific equal length header. At least this is what I'm beginning to realize as it relates to "middle of the HP road" turbocharged engines.

[8valves]

As long as that statement stays for "middle of the road" setups as you put it, then I would agree. I personally agree that in strong setups an equal length is very important, and a vital part of making big power. Remember, when you get to that point a divided tang entry turbine should more than likely be used as well, so an equal length is needed to take advantage of that as well.

AM

[puppet]

As long as that statement stays for "middle of the road" setups as you put it, then I would agree. I personally agree that in strong setups an equal length is very important, and a vital part of making big power. Remember, when you get to that point a divided tang entry turbine should more than likely be used as well, so an equal length is needed to take advantage of that as well.

AMAbsolutely. Those divided inlets, combined with the right header design (like our TBI for instance), look to help some with turbo spool down low. One of the thoughts that got me to reseaching this all in the first place. After the pressure rises in the exhaust though there doesn't seem to be any evidence that they matter either. That rapid high pressure rush makes big power.
The header used to make the divided inlet work best as far as spooling is concerned, would have a smaller tube cross section. Smaller cross sectional runners can't deliver good top end power.

[8valves]

Absolutely. Those divided inlets, combined with the right header design (like our TBI for instance), look to help some with turbo spool down low. One of the thoughts that got me to reseaching this all in the first place. After the pressure rises in the exhaust though there doesn't seem to be any evidence that they matter either. That rapid high pressure rush makes big power.
The header used to make the divided inlet work best as far as spooling is concerned, would have a smaller tube cross section. Something that would kill top end power.


With the right length employed, tube cross sectional area can be increased. Only when you get into super long tube designs like Stephane's do I think diameter becomes something to take into consideration. Out long tube top mount, equal length header for our Talon race car has somewhere between 1 5/8" and 1 7/8" tube diamter, i can't remember off the top of my head.

AM

[puppet]

With the right length employed, tube cross sectional area can be increased. Only when you get into super long tube designs like Stephane's do I think diameter becomes something to take into consideration. Out long tube top mount, equal length header for our Talon race car has somewhere between 1 5/8" and 1 7/8" tube diamter, i can't remember off the top of my head.

AMEven so, from what I've read, your choices on length and diameter still move you into a 200-500 rpm "golden zone". A place where the engine is flowing the greatest and making the most power. Change the perameters and you move the zone.

[LynX853]

wow i had no idea that this thread would spark up such a big convo, personally I was just trying to find header pieces that could be adapted to our cars with the only fabrication being flange swap. we're not the only motors with limited space... and in my domestic mind of thinking I was looking for SVO headers... which still arnt that cheep. but now I realized from puppet that honda stuff is pretty cheep too, cause there's just so much aftermarket for em.. any more oppinions would be awesome.
i guess that just after seeing the TU results on the flow of a stock TD log and even a ported TD log... i was horrified by how bad they are flow wise. it made me go with a tbi header (ported) which almost flows twice as much.

[turbovanman²]

SMP tested his against a Log and picked up some nice power, and it would fit in a stock vehicle with no major mods. There is a Honda vid of a guy testing a log header then changing over to equal length, picked up power and reduced the lag.



why is the turbo junk?

Guess you have never seen the pics of the 2 compressor halves glued together. That turbo is the cheapest of cheap, I doubt it really even has a real bearing installed. The turbine is cheap pot metal. Most last a month or so if your lucky, push it hard and it lets go. A few members tried them for sh*ts and giggles, KABOOM!

[BadAssPerformance]

Need to see back to back dyno sheets :thumb:

[puppet]

i guess that just after seeing the TU results on the flow of a stock TD log and even a ported TD log... i was horrified by how bad they are flow wise. it made me go with a tbi header (ported) which almost flows twice as much.Flow is going to be a function of the turbo you have bolted to the end of the mani. All of them induce a degree of backpressure.

[turbovanman²]

Ok boys, heres 19 pages, happy reading-

http://www.turbododge.com/forums/showthread.php?t=47844&highlight=header

[puppet]

Seen it ... read it a dozen times. Have SMP's great work saved in some image files. Some great posts in that thread ... some not so great.

This pretty much sums it up .. from the horses mouth:
http://www.turbododge.com/forums/showpost.php?p=849464&postcount=238

[turbovanman²]

Seen it ... read it a dozen times. Have SMP's great work saved in some image files. Some great posts in that thread ... some not so great.

This pretty much sums it up .. from the horses mouth:
http://www.turbododge.com/forums/showpost.php?p=849464&postcount=238


I was looking for that post but gave up after 5 pages, :nod:

[The S is Silent]

What order are you supposed to weld a manifold together like that? Do you start at the collector and build the pieces towards the head, or do you start at the head flange and built towards the turbo. Doing a complex manifold like that, there is probably and order that you want to do things to prevent the welds from putting stress on each other, etc. I'm afraid cutting off the flange and putting on our own would lead to two problems...

1) Stress on the other welds in the manifold, causing it to crack.
2) Getting the flange flat. You better get one hell of a flange to weld that sucker to, because you're going to have to shave A LOT of material off some spots to get it to sit flat after you are done welding on it.

For $750, you might as well get one tailor made to our cars. Cheaping out like this and cutting/re-welding is going to cost you more in the long run than paying one guy the cash to make it right. My $0.02.

[turbojunker]

That looks like the ATR header. That thing is a crack factory anyway.

[JuXsA]

to bad they don't make it for the public... I would bet that if you called SMP enough and begged and cried enough that frenchy would make you one though.... When I get a uber badass head done I may beg and plead for him to make me one. I need to find out how well his ported head do any way. I have been leaning on either lonewolfperformance or mpgmike to do a head...

[BadAssPerformance]

With all the talk... if I get some free time... I'll have to re-investigate the cost to duplicate this badboy (http://www.badassperformance.com/mstore/bap_parts/header/header.html)

[Whorse]

Now that's a nice header. What about with a big external W/G installed?

[The S is Silent]

JT, if it fits without any masaging of the firewall, I'll take one. I'd be willing to pay $500-$750 for one possibly.

The name fits that thing well. It sure as hell is badass!

[BadAssPerformance]

Now that's a nice header. What about with a big external W/G installed?

Thanks. Should be able to add a 5th pipe if needed

[BadAssPerformance]

JT, if it fits without any masaging of the firewall, I'll take one. I'd be willing to pay $500-$750 for one possibly.

The name fits that thing well. It sure as hell is badass!

It fits my Z w/o massaging the firewall with a T3/T4B hybrid on it. The rear coolant -AN elbow is ~ 1" off the wall, but I have solid mounts so it is not an issue. I still need to fit on an Omni to see for sure tho.

Thanks,

[puppet]

It fits my Z w/o massaging the firewall with a T3/T4B hybrid on it. The rear coolant -AN elbow is ~ 1" off the wall, but I have solid mounts so it is not an issue. I still need to fit on an Omni to see for sure tho.

Thanks,On my daytona the stock mani/turbo housing combo has about 1-1/2" clearance ... so 1" isn't so bad.

[LynX853]

do you have flow numbers for it JT?

[BadAssPerformance]

do you have flow numbers for it JT?

Not yet. I will see about getting them the next time I have it off longer than just for a HG job.

[turbovanman²]

That is nice JT, I bet it would wake an engine up nicely.

[TurboGLH]

That looks like the ATR header. That thing is a crack factory anyway.

I'm pretty sure that if stephan can build this,

http://www.turbo-mopar.com/forums/photopost/data/579/SatBeforeQualify4.JPG

and can go this fast..

http://nhrasportcompact.com/2006/events/race06/results/hr.html

with a 20yo car and a 15yo motor then he can build a header that won't crack.

[BadAssPerformance]

That is nice JT, I bet it would wake an engine up nicely.

thanks, and it does... still pulling at 7000.

[BadAssPerformance]

I'm pretty sure that if stephan can build this,

http://www.turbo-mopar.com/forums/photopost/data/579/SatBeforeQualify4.JPG

and can go this fast..

http://nhrasportcompact.com/2006/events/race06/results/hr.html

with a 20yo car and a 15yo motor then he can build a header that won't crack.

I'll second that action :thumb:

[Frank]

Seen it ... read it a dozen times. Have SMP's great work saved in some image files. Some great posts in that thread ... some not so great.

This pretty much sums it up .. from the horses mouth:
http://www.turbododge.com/forums/showpost.php?p=849464&postcount=238


Funny you should mention that particular post (not the topic).... that is chronoss writing that thread under the smp login... not stephane, but it still applies.

As for the technical reasons for alot of the arguements, it is very key even after all of it. I do like your above statement stating that a well designed log is the best for "middle of the road" cars. I am going to scan in later the latest Engine Master's dyno testing of collectors and such.... pretty key information that IMHO applies even more to turbo cars because the pressure differential accross sections of a manifold/header cause for great velocities and turbulence potential.

You found some good links there.... nice.



Frank

[turbovanman²]

Funny you should mention that particular post (not the topic).... that is chronoss writing that thread under the smp login... not stephane, but it still applies.

As for the technical reasons for alot of the arguements, it is very key even after all of it. I do like your above statement stating that a well designed log is the best for "middle of the road" cars. I am going to scan in later the latest Engine Master's dyno testing of collectors and such.... pretty key information that IMHO applies even more to turbo cars because the pressure differential accross sections of a manifold/header cause for great velocities and turbulence potential.

You found some good links there.... nice.



Frank

I await your links, as usual, :thumb:

[turbojunker]

I'm pretty sure that if stephan can build this,

http://www.turbo-mopar.com/forums/photopost/data/579/SatBeforeQualify4.JPG

and can go this fast..

http://nhrasportcompact.com/2006/events/race06/results/hr.html

with a 20yo car and a 15yo motor then he can build a header that won't crack.


I'm pretty sure I know who he is, and what he has done.

I'm also pretty sure I was talking of the other header being the ATR piece. Thanks for trying to make me look dumb though, really.

[TurboGLH]

I'm pretty sure I know who he is, and what he has done.

I'm also pretty sure I was talking of the other header being the ATR piece. Thanks for trying to make me look dumb though, really.

You don't have to thank me, you did a fine job all by yourself. But really though, your post seemed to indicate that you thought either the header in question or just the basic design was questionable and I felt that a correction was in order. If you took that personally then I don't know what to tell you, but you shouldn't have.

[Frank]

Here guys go... nice article... Had to use my camera since the scanner wasnt working. :thumb:
http://www.squirrelpf.com/articles/exh_tuning.php

[Whorse]

Great article Frank. Some very interesting results. Curious how this would relate to turbo cars, however.

[Frank]

It changes drastically with turbo car because speed of sound changes. However it does prove that collectors need to be well designed in the one test. Overall its just nice to see the real numbers.

Frank

[turbovanman²]

I love the extension and no collector test. I extended the collectors on my B250 360 engine, aprox 18 inches and picked up some serious bottom end and that article proves my but meter was right, :nod:

[Directconnection]

That turbo you linked to is junk, figure on it lasting 1-2 weeks, if your lucky.

Why is it junk? I know for the price...it is suspect...but what have you heard?

[BadAssPerformance]

Why is it junk? I know for the price...it is suspect...but what have you heard?

I thought cuz its only $200 but then saw this...


Guess you have never seen the pics of the 2 compressor halves glued together. That turbo is the cheapest of cheap, I doubt it really even has a real bearing installed. The turbine is cheap pot metal. Most last a month or so if your lucky, push it hard and it lets go. A few members tried them for sh*ts and giggles, KABOOM!

[turbovanman²]

Why is it junk? I know for the price...it is suspect...but what have you heard?

I've also seen one, Fast4Ward bought one and he brought it over, all I can say is wow, :( :lol: The old saying, you get what you pay for has never rung more true in this case.

[TurboGLH]

Do a search for zy turbo's. They're a chinese knockoff company that makes crappy cheap turbos that are cast with an assortment of turboxs, garrett and the Turbonetics T logos on the turbos.

[Frank]

Thats the Chinease for you! Hell when they copied a plane from the russians, they even copied the logos on the rudder pedals!!! LOL


Frank

[Directconnection]

Nice.

[puppet]

Found an interesting post on another forum about turbo exhaust theory from a pretty good source:

'The following excerpts are from Jay Kavanaugh, a turbosystems engineer at Garret, responding to a thread on http://www.impreza.net regarding exhaust design and exhaust theory:

“Howdy,

This thread was brought to my attention by a friend of mine in hopes of shedding some light on the issue of exhaust size selection for turbocharged vehicles. Most of the facts have been covered already. FWIW I'm an turbocharger development engineer for Garrett Engine Boosting Systems.

N/A cars: As most of you know, the design of turbo exhaust systems runs counter to exhaust design for n/a vehicles. N/A cars utilize exhaust velocity (not backpressure) in the collector to aid in scavenging other cylinders during the blowdown process. It just so happens that to get the appropriate velocity, you have to squeeze down the diameter of the discharge of the collector (aka the exhaust), which also induces backpressure. The backpressure is an undesirable byproduct of the desire to have a certain degree of exhaust velocity. Go too big, and you lose velocity and its associated beneficial scavenging effect. Too small and the backpressure skyrockets, more than offsetting any gain made by scavenging. There is a happy medium here.

For turbo cars, you throw all that out the window. You want the exhaust velocity to be high upstream of the turbine (i.e. in the header). You'll notice that primaries of turbo headers are smaller diameter than those of an n/a car of two-thirds the horsepower. The idea is to get the exhaust velocity up quickly, to get the turbo spooling as early as possible. Here, getting the boost up early is a much more effective way to torque than playing with tuned primary lengths and scavenging. The scavenging effects are small compared to what you'd get if you just got boost sooner instead. You have a turbo; you want boost. Just don't go so small on the header's primary diameter that you choke off the high end.

Downstream of the turbine (aka the turboback exhaust), you want the least backpressure possible. No ifs, ands, or buts. Stick a Hoover on the tailpipe if you can. The general rule of "larger is better" (to the point of diminishing returns) of turboback exhausts is valid. Here, the idea is to minimize the pressure downstream of the turbine in order to make the most effective use of the pressure that is being generated upstream of the turbine. Remember, a turbine operates via a pressure ratio. For a given turbine inlet pressure, you will get the highest pressure ratio across the turbine when you have the lowest possible discharge pressure. This means the turbine is able to do the most amount of work possible (i.e. drive the compressor and make boost) with the available inlet pressure.

Again, less pressure downstream of the turbine is goodness. This approach minimizes the time-to-boost (maximizes boost response) and will improve engine VE throughout the rev range.

As for 2.5" vs. 3.0", the "best" turboback exhaust depends on the amount of flow, or horsepower. At 250 hp, 2.5" is fine. Going to 3" at this power level won't get you much, if anything, other than a louder exhaust note. 300 hp and you're definitely suboptimal with 2.5". For 400-450 hp, even 3" is on the small side.”

"As for the geometry of the exhaust at the turbine discharge, the most optimal configuration would be a gradual increase in diameter from the turbine's exducer to the desired exhaust diameter-- via a straight conical diffuser of 7-12° included angle (to minimize flow separation and skin friction losses) mounted right at the turbine discharge. Many turbochargers found in diesels have this diffuser section cast right into the turbine housing. A hyperbolic increase in diameter (like a trumpet snorkus) is theoretically ideal but I've never seen one in use (and doubt it would be measurably superior to a straight diffuser). The wastegate flow would be via a completely divorced (separated from the main turbine discharge flow) dumptube. Due the realities of packaging, cost, and emissions compliance this config is rarely possible on street cars. You will, however, see this type of layout on dedicated race vehicles.

A large "bellmouth" config which combines the turbine discharge and wastegate flow (without a divider between the two) is certainly better than the compromised stock routing, but not as effective as the above.

If an integrated exhaust (non-divorced wastegate flow) is required, keep the wastegate flow separate from the main turbine discharge flow for ~12-18" before reintroducing it. This will minimize the impact on turbine efficiency-- the introduction of the wastegate flow disrupts the flow field of the main turbine discharge flow.

Necking the exhaust down to a suboptimal diameter is never a good idea, but if it is necessary, doing it further downstream is better than doing it close to the turbine discharge since it will minimize the exhaust's contribution to backpressure. Better yet: don't neck down the exhaust at all.

Also, the temperature of the exhaust coming out of a cat is higher than the inlet temperature, due to the exothermic oxidation of unburned hydrocarbons in the cat. So the total heat loss (and density increase) of the gases as it travels down the exhaust is not as prominent as it seems.

Another thing to keep in mind is that cylinder scavenging takes place where the flows from separate cylinders merge (i.e. in the collector). There is no such thing as cylinder scavenging downstream of the turbine, and hence, no reason to desire high exhaust velocity here. You will only introduce unwanted backpressure.

Other things you can do (in addition to choosing an appropriate diameter) to minimize exhaust backpressure in a turboback exhaust are: avoid crush-bent tubes (use mandrel bends); avoid tight-radius turns (keep it as straight as possible); avoid step changes in diameter; avoid "cheated" radii (cuts that are non-perpendicular); use a high flow cat; use a straight-thru perforated core muffler... etc.”

"Comparing the two bellmouth designs, I've never seen either one so I can only speculate. But based on your description, and assuming neither of them have a divider wall/tongue between the turbine discharge and wg dump, I'd venture that you'd be hard pressed to measure a difference between the two. The more gradual taper intuitively appears more desirable, but it's likely that it's beyond the point of diminishing returns. Either one sounds like it will improve the wastegate's discharge coefficient over the stock config, which will constitute the single biggest difference. This will allow more control over boost creep. Neither is as optimal as the divorced wastegate flow arrangement, however.

There's more to it, though-- if a larger bellmouth is excessively large right at the turbine discharge (a large step diameter increase), there will be an unrecoverable dump loss that will contribute to backpressure. This is why a gradual increase in diameter, like the conical diffuser mentioned earlier, is desirable at the turbine discharge.

As for primary lengths on turbo headers, it is advantageous to use equal-length primaries to time the arrival of the pulses at the turbine equally and to keep cylinder reversion balanced across all cylinders. This will improve boost response and the engine's VE. Equal-length is often difficult to achieve due to tight packaging, fabrication difficulty, and the desire to have runners of the shortest possible length.”
"Here's a worked example (simplified) of how larger exhausts help turbo cars:

Say you have a turbo operating at a turbine pressure ratio (aka expansion ratio) of 1.8:1. You have a small turboback exhaust that contributes, say, 10 psig backpressure at the turbine discharge at redline. The total backpressure seen by the engine (upstream of the turbine) in this case is:

(14.5 +10)*1.8 = 44.1 psia = 29.6 psig total backpressure

So here, the turbine contributed 19.6 psig of backpressure to the total.

Now you slap on a proper low-backpressure, big turboback exhaust. Same turbo, same boost, etc. You measure 3 psig backpressure at the turbine discharge. In this case the engine sees just 17 psig total backpressure! And the turbine's contribution to the total backpressure is reduced to 14 psig (note: this is 5.6 psig lower than its contribution in the "small turboback" case).

So in the end, the engine saw a reduction in backpressure of 12.6 psig when you swapped turbobacks in this example. This reduction in backpressure is where all the engine's VE gains come from.

This is why larger exhausts make such big gains on nearly all stock turbo cars-- the turbine compounds the downstream backpressure via its expansion ratio. This is also why bigger turbos make more power at a given boost level-- they improve engine VE by operating at lower turbine expansion ratios for a given boost level.

As you can see, the backpressure penalty of running a too-small exhaust (like 2.5" for 350 hp) will vary depending on the match. At a given power level, a smaller turbo will generally be operating at a higher turbine pressure ratio and so will actually make the engine more sensitive to the backpressure downstream of the turbine than a larger turbine/turbo would. As for output temperatures, I'm not sure I understand the question. Are you referring to compressor outlet temperatures?"'

http://www.rx7club.com/showthread.php?t=476631&page=3&pp=15&highlight=equal+length

[Directconnection]

With all the talk... if I get some free time... I'll have to re-investigate the cost to duplicate this badboy (http://www.badassperformance.com/mstore/bap_parts/header/header.html)

I actually like that one alot. Except for me cutting a tunnel into the firewall :) Does it actually fit?

Got an extra for me to try for you? :eyebrows:

[turbovanman²]

Downstream of the turbine (aka the turboback exhaust), you want the least backpressure possible. No ifs, ands, or buts. Stick a Hoover on the tailpipe if you can. ]


I love that quote, :lol:

Thats awesome Puppet, great find. The header theory is excellent.

[puppet]

Coolest thing is that the guys at garret visit a board sometimes. Be something to get them to drop in on one of our forums once in awhile ... just to pick brain cells.

[Frank]

Ya I would like them to validate my current version of my turbocalculator

[BadAssPerformance]

I actually like that one alot. Except for me cutting a tunnel into the firewall :) Does it actually fit?

Got an extra for me to try for you? :eyebrows:

LOL, it fits on my Z w/o touching the fire wall. With the Z down, and soon as a get a chance to take it off I will see if it fits am L-body.

[Directconnection]

Coolest thing is that the guys at garret visit a board sometimes. Be something to get them to drop in on one of our forums once in awhile ... just to pick brain cells.


It would be especially cool since our cars came with garretts from the factory unlike hondas and mitsus.