Turbocharged header length

[Boport]

Hi,

I just got Larry's Pipemax program and have come up with some optimal header primary lengths for a N/A application. I'm really putting a lot of effort into the header build and am having trouble trying to package 28-30" of header tube in my turbo application. I want to keep the header primaries a tuned length, using a well designed merge collector. I feel I have enough exhaust housing A/R to keep pressure ratio down enough to benefit from a tuned length for scavenging.

My question is what kind of affect would shortening the primary tubes by half the specified length do to the engine's peak power range? Is the wave tuning going to go out of the window? Or is the only way to truely capture the wave's energy by staying with a long 28-30" of length? What are my options?

Thanks in advance,

Bo

[JBV-HEADS]

Bo,

I don’t mean to speak for Larry, but if you look at the shorty header example, you may find your answer. Both systems will work much the same in theory and principle. My only question would be if your turbo would act exactly like a diffuser box. I haven’t met the man yet who has answered that one to my satisfaction . Hopefully Larry or someone can shine a little light on that one. Good luck,

Joe

[INTMD8]

I know it's not what you asked, and I don't have an answer for you, but I personally build turbo headers with primaries as short as possible, with no regard to equal length.

I've found this makes the system very responsive (no boost/boost transient), and IMHO, pulse tuning on a turbo engine is worth very very little. (partly because backpressure will almost always eclipse boost pressure, and if you are somehow able to reverse that, your boost curve will most likely resemble that of a centrifugal supercharger).

An example would be w2w powertrain built a turbocharged LS1 that made over 1500 horsepower with untouched truck exhaust manifolds.

I've built many 1000+hp combinations with unequal length headers.

Again, don't want to stray off the topic, I just don't think you have much to benefit from the amount of work involved.

[JBrady]

This picture may be worth examining. Burns Stainless has a fine reputation for exhaust header engineering so to make this their cover photo must be saying something.

[JBV-HEADS]

Interesting photo. It shows headers that would fit Bo’s project in the lengths of 15 to 17 inches as Pipemax suggest for a shorty header. It’s also designed in a 1-4 and 2-3 coupling for a 180 degree design in 4 cylinders . Burns and Ed’s are the 2 most common header parts places I look. http://www.burnsstainless.com/ and the others is http://www.headersbyed.com/
I’m sure there are many other good ones, but they cover just about anything you’d like. I have only a passing interest in turbos, but thanks for adding a little knowledge to it .

Joe

[HiBoost]

I sell turbos for a living and deal with hundreds of different turbocharged configurations a year and I can tell you that equal length is not only not required, it's almost non-existant in the real world on turbo applications. Testing HAS shown that there are some gains to building the "ideal" header configuration, but there's much more to it than just the runner length. Runner diameter is also key. And in many cases the power gains that are achieved with the exotic designs (like Burns) are from the "multi level" design, for example 6-2-1 for an inline 6 vs. just 6-1.

I have closely examined the headers on many, many 2000+ hp cars and to date I have only seen one that was equal length. And that car wasn't the fastest car in its class by any stretch Like JBrady said, the high backpressure in many ways seems to minimize the pulse tuning effect. Shorter runners will allow for more heat to make it into the turbine and heat energy is what spools the turbo, not just gas volume. On turbo motors compromises are often made to aid in spooling the turbo. For example, look at the camshaft specs on a typical turbo motor. Instead of the 240/250 duration that you'd see on a blower or N2O motor, you'll see something like 240/232. The exhaust is purposely held closed as long as possible so that when it finally opens there is a "burst" of pressure to kick start the turbine wheel. This sacrificies some motor efficiency (pumping losses) in the name of quicker spool, but the thought (and reality) is that the boost is going to make the power back a hundred fold, so just do whatever you need to get the boost.

[Boport]

Okay, lets rephrase the question....

In a N/A engine that calls for a 28" long primary, what effect would cutting this primary length in half cause?

Bo

[HiBoost]

huh? are you saying that the motor wouldn't be turbo'd anymore? or are you saying that if this same motor was N/A, it's ideal length would be 28", so now what effect does cutting it down to 14" have when turbo'd?

[Boport]

Thats exactly what I'm asking.

[HiBoost]

I don't think anybody can give a black and white answer to that without having 10,000 other variables answered and running a complete simulation. I will tell you that 14" is by no means alarmingly short. I've seen lengths equal to or less than that on plenty of BIG power turbocharged vehicles. Most of the twin turbo setups (on V8's) have the front most cylinder in each bank making a right turn and going directly into the turbine housing. I'm talking about a 6-7" tube at most, and this works just fine. Would it gain 5hp if you went through some crazy alternate path to add another 20" to the length? Maybe. Maybe not. In my opinion even if we said that pulse tuning *did* matter on a turbo application, I still believe that "shortest, straightest path" has higher priority. In other words, there is more restriction in traveling through 20" of 1.5" tubing than traveling through 5" of 1.5" tubing. And I'd rather send gas through 10" of straight than 10" of 180 degree bend. So if we're comparing "short and straight" to "long and curvy" I would always choose the former.

[Bos's5.0]

An example would be w2w powertrain built a turbocharged LS1 that made over 1500 horsepower with untouched truck exhaust manifolds.

.

Do you have a link? I find this fascinating and have to see it with my own eyes. Thanks..

[INTMD8]

http://ls1tech.com/forums/showthread.ph ... ge=1&pp=10

Also, fwiw, I re-read the post and they were corvette exhaust manifolds.


Here is the one that used the truck manifolds-

http://ls1tech.com/forums/showthread.ph ... ge=1&pp=10


And, while I'm posting stuff, here's the system I built for our shop car a while back. 370ci, hyd roller, ls6 intake, 994rwhp 863rwtq through the exhaust and a turbo 400 trans. (88mm turbo, 22psi boost)

http://www.ls1speed.com/artwork/shopcar/large/008.jpg

http://www.ls1speed.com/artwork/shopcar/large/007.jpg

http://www.ls1speed.com/artwork/turbo/graph2B.jpg

[Bos's5.0]

http://ls1tech.com/forums/showthread.ph ... ge=1&pp=10

Also, fwiw, I re-read the post and they were corvette exhaust manifolds.


Here is the one that used the truck manifolds-

http://ls1tech.com/forums/showthread.ph ... ge=1&pp=10


And, while I'm posting stuff, here's the system I built for our shop car a while back. 370ci, hyd roller, ls6 intake, 994rwhp 863rwtq through the exhaust and a turbo 400 trans. (88mm turbo, 22psi boost)

http://www.ls1speed.com/artwork/shopcar/large/008.jpg

http://www.ls1speed.com/artwork/shopcar/large/007.jpg

http://www.ls1speed.com/artwork/turbo/graph2B.jpg

WOW
The design is SOOOOOOO simple. There are guys building these intricate tube manifolds for their 500hp engines... I'm at a loss for words.

Intmd8---absolutely gorgeous setup. But I wonder what you think when you see them use stock manifolds (making 1400+hp) after building those beautiful headers?

[Grocerius Maximus]

The photo posted has a 4 into 2 collector because that is a divided housing T4. There are two scrolls inside, they do not converge until the turbine wheel tip. This tends to help lower boost threshold.

A properly done header/collector will help, but its so very seldom that you have the room to do it. Its more of a race car only thing, where you MAKE room for the header, rather than put the header where you can. Besides the fact a good 321 SS header set with a merge collector and hardware is going to cost you a whole bunch of money on a V-8. Can easily exceed 3 grand in materials costs alone.

Boost threshold, power, and RECOVERY are improved, especially recovery. Not uncommon to see .1-.2 seconds from throttle lift to full boost instead of .5-.6 seconds with just a well done header/merge collector. Its not just heat that makes a turbine work, its pulse energy/velocity too.

Them F1 guys werent stupid, you didn't see any log manifolds on those mid 80's turbo cars. Every possible advantage was used.

Is it necessary to have a header to make good power? No. But you won't get everything you could get out of it without one.

[maxracesoftware]

The photo posted has a 4 into 2 collector because that is a divided housing T4. There are two scrolls inside, they do not converge until the turbine wheel tip. This tends to help lower boost threshold.

A properly done header/collector will help, but its so very seldom that you have the room to do it. Its more of a race car only thing, where you MAKE room for the header, rather than put the header where you can. Besides the fact a good 321 SS header set with a merge collector and hardware is going to cost you a whole bunch of money on a V-8. Can easily exceed 3 grand in materials costs alone.

Boost threshold, power, and RECOVERY are improved, especially recovery. Not uncommon to see .1-.2 seconds from throttle lift to full boost instead of .5-.6 seconds with just a well done header/merge collector. Its not just heat that makes a turbine work, its pulse energy/velocity too.

Them F1 guys werent stupid, you didn't see any log manifolds on those mid 80's turbo cars. Every possible advantage was used.

Is it necessary to have a header to make good power? No. But you won't get everything you could get out of it without one.

Is it necessary to have a header to make good power? No. But you won't get everything you could get out of it without one

what Grocerius Maximus said

sorry for not reading this Thread sooner...i usually stay away from the
Turbo and Blower Posts because i don't have enough Dyno Data
on these to back me up.

just got Larry's Pipemax program and have come up with some optimal header primary lengths for a N/A application. I'm really putting a lot of effort into the header build and am having trouble trying to package 28-30" of header tube in my turbo application. I want to keep the header primaries a tuned length, using a well designed merge collector. I feel I have enough exhaust housing A/R to keep pressure ratio down enough to benefit from a tuned length for scavenging

they will work just OK at the 1st time you "halve" the lengths,
like=> going from your 28-30" to 14.0-15" ...but with reduced Torque
and Power Curve width (naturally aspirated)...and also the Primary Pipes
are not exactly halved in length for next best tuned point, but longer than half.

just look at the Shorty Headers out there on V8 engines,
if you Dyno test them, even if they are somewhat unequal in Lengths,
for example=> 1 or 2 Pipes might be 28" long, then the shortest might be
16.5"..they will workout OK most times.
on NA V8 engines there 's more to be gained with
Collector Lengths + Collector diameters

for Turbos=> what Grocerius Maximus said