L6 Turbo Header Group Buy

[col]

My vote would be for equal length.

If we are going to the trouble to have these made, so we can get better performance, why be concerned about changing the exhaust to suit it.

I think we will only get one chance to get these made cheaply.

Go for the best performance possible.

That's my vote anyway.

[jgkurz]

Quantity is the key. A Yugo would cost as much as a Ferrari if you only built one. That's why it's beneficial to do a group buy...

 

I couldn't agree more!!!

 

My vote would be for equal length.

If we are going to the trouble to have these made, so we can get better performance, why be concerned about changing the exhaust to suit it.

I think we will only get one chance to get these made cheaply.

Go for the best performance possible.

That's my vote anyway.

 

The perfect turbo header would have equal length primaries and would have the tubes pulse tuned to take advantage of a divided turbine but this is not practical for the masses. Here's my vote for options:

 

1) I'd prefer a T3 flange but the option for either T3 or T4 would be desirable. T3 would probably be the majority of the orders.

 

2) Primaries should be about 1 5/8 and made of thick gauge tubing. The header should NOT be a log style but should accommodate A/C and should have all primaries merge together just before the turbo flange.

 

3) Wastegate location will need careful mock-up. The entry point should be next to the turbo flange so the wastegate port see's all cylinder pulses. The wastegate flange should be in a location that allows the WG can be tucked between the header and the the block. Something like this:

or this:

 

 

 

4) For the wastegate flange I'd prefer the larger 40mm flange but the 38mm will be more common. Some people may even want the 44mm or larger. The option for either would be desirable. See here: http://www.tialsport.com/prod_wg_fl.htm

 

5) The cylinder head flange is also a concern. Will the same shop be creating a flange or do we need to supply separately?

 

6) I'm not concerned about a downpipe since I want to custom build my own so it's fits my car properly.

 

7) Will we have the option for a high-temp coating?

[stprasinz]

equal lenght isn't important in a turbo manifold. the equal length of an na header allows the cylinders to have equal back pressure as to where in a turbo design the turbo creates a back pressure wich is equal throughout the entire manifold. as for the wastegate, I would say it is a givin.. and the flange would probably be best a s a t3.. they spool up pretty quick and get a stage 5 wheelk and your good to go.. as for materiel thicker mild.. as for wether tubular or log style.. I think log would be a bit cheaper, on the manufacturing but more for the product...as for the price if its a quality peice I would be willing to pay 350-450, if not 175 and I'll take 2 lol....

 

anyway I'm am alos in...

[col]

If equal length is not important how come all the big tuners, getting huge hp use them.

I'm sure it's not just because they look pretty.

People go to great length to balance, blueprint, port matching, even balancing rocker gear. You tell mean engine that is in perfect balance won't be put off balance by having one runner 12 inches longer than the other before it hits the turbine.

I'm not saying the log won't be an improvement over standard. Just why not go for the best possible system.

[col]

Why is the pulse tuned, divided manifold ,not for the masses?

As long as it can be squeezed under the intake I see no reason not to modify the exhaust to fit.

It's been claimed, the tuned , divided manifold, could help spool by as much as 1000 rpm. Isn't that worth a bit of exhaust work?

These manifolds will be so much cheaper than getting " a one off " made the money saved (or just a small amount of it) could be spent on the exhaust.

But if I'm the only one thinking this way, I will shut up as the only way this will work is in bulk purchase.

[TrumpetRhapsody]

A split pulse equal length manifold would be nice, I think everyone would agree, I know I'd like one if possible... but it comes down to cost. We can talk semantics once we get more info and costs from the builder

[Soundmasterg]

Count me in on one of these too, though at this point I'm still new to the game and am not sure what options I would want. I don't know the difference between the T3 or T4 for example.

 

Greg

[jgkurz]

If equal length is not important how come all the big tuners, getting huge hp use them.

I'm sure it's not just because they look pretty.

People go to great length to balance, blueprint, port matching, even balancing rocker gear. You tell mean engine that is in perfect balance won't be put off balance by having one runner 12 inches longer than the other before it hits the turbine.

I'm not saying the log won't be an improvement over standard. Just why not go for the best possible system.

 

Why is the pulse tuned, divided manifold ,not for the masses?

As long as it can be squeezed under the intake I see no reason not to modify the exhaust to fit.

It's been claimed, the tuned , divided manifold, could help spool by as much as 1000 rpm. Isn't that worth a bit of exhaust work?

These manifolds will be so much cheaper than getting " a one off " made the money saved (or just a small amount of it) could be spent on the exhaust.

But if I'm the only one thinking this way, I will shut up as the only way this will work is in bulk purchase.

 

It's a matter of space and compromise. The people who want a header to build an all out "max effort" engine will certainly want an equal length pulse tuned header. In my opinion the header should be built to accommodate both the "max effort" crowd as well as the daily driver folks with A/C. We will be better off by compromising a just a bit so we can make the group buy more attractive for more people. I think we all win of we can agree on a design that accomplishes this. In the end some people will be disappointed because the design won't be engineered to perfection. I don't think that can be avoided. If some one wants to spend the time to mock up an equal length pulse tuned header that accommodates A/C and doesn't come too close to my frame rails then I'm all for it. However, I think this would be an unrealistic and enormous undertaking to make sure it fit both the S130 and S30 cars. BTW, I think 1000 rpm spool improvement with a pulse tuned split header is a bit optimistic. Please school me if you have info to the contrary.

[jeffer949]

Honestly i dont think a completely equal length turbo manifold will happen. it would more than likely not allow for A/C use which i think would kill this for a group buy. The people that are looking for the max effort turbo header will more then likely have already had ones custom made to there purpose. What i think we will get out of this group buy is a very nice well flowing manifold that will out flow the stock by a lot. I think if we stick with the manifold design that i posted earlier it will satisfy "most" of our crowd.

 

I still need some input on what size to have the runners made. Also do you think a 44mm v-band waste gate would work well for us? I know that alot of people are saying to go with a 38mm flange but ive been hearing that some people are getting some pretty large boost creep with the 38 so i say we should plan ahead and go with the 44mm. That would also take away an issue of them welding the flange on in the wrong position like was posted in another thread.

[savageskaterkid]

I believe it was in MAXIMUM BOOST that they won't over wastegates, I can't find the book, so don't quote me. But if you run a BIG turbo at Low boost, you want a big WG, if you run a small turbo at high boost, you use a small wastegate, if you run a big turbo at high boost, you use a small wastegate. Does that seem right? V-band does seem the way to go now though, specially for ease of removal.

[zeeboost]

I'm definately interested in this...

[TONY C]

savageskaterkid is correct. 38mm wastegate 2 bolt flange prefered. t3 turbo flange.

 

if all goes well have a group for a 44mm wg and a t4 flange. later.

 

If you run a quality wastegate like Tial or the like and a proper boost controller. you will have no creep.

[Nigel]

I believe it was in MAXIMUM BOOST that they won't over wastegates, I can't find the book, so don't quote me. But if you run a BIG turbo at Low boost, you want a big WG, if you run a small turbo at high boost, you use a small wastegate, if you run a big turbo at high boost, you use a small wastegate. Does that seem right? V-band does seem the way to go now though, specially for ease of removal.

 

I had a quick look through the book, and I couldn't find any reference to this (not saying it's not there, I just couldn't find it). Doing a quick search on line I came up with what I've pasted below, and I've read this several times before on other sites. A local, well respected turbo builder has also told me the same thing. In a nutshell, if you want to run high boost (>~18psi), then use a smaller wastegate, if low boost (<~18psi), then use a larger wastegate.

 

*EDIT* this is more or less what savageskaterkid said. But, what's a small turbo, and what's a big turbo? From research I was doing a year ago, I recall that for a T3/T4 turbo running less than 18psi, a 44mm WG appeared to be the best choice.*END EDIT*

 

This is from Performance Car Magazine

(http://forums.performancecar.co.nz/viewtopic.php?f=37&p=455903

1. The wastegate size is relevant to how much horsepower you are targeting

2. If you want to run high boost, then a smaller wastegate is better than a larger wastegate. The idea being that in order to generate high boost you need most of the exhaust gas going through the turbine, not through the wastegate.

3. If you want to run low boost then a larger wastegate is better than a smaller wastegate. The idea being that in order to keep the boost low you need a lot of the exhaust gas going through the wastegate not through the turbine.

 

But what is high boost? Well for the sake of this discussion I have settled on 1.2 to 1.4 bar (18 to 21 psi) as being the divider, thus 1. 2 bar and under is low and 1.4 bar and above is high. How did I arrive at this number? Well based on the results of the surveys, this seems to be the most common point where the wastegate sizes change from theory 2 to theory 3 (above).

 

The next bit of theory is that it takes 1 lb per minute of airflow to make 11 bhp in a current generation 4 valve engine. This is a pretty well established piece of turbo sizing philosophy. But how do we relate this to wastegate sizing? Well referring to the results of the surveys, it seems a straight 1 to 1 relationship is not too far from the average, so 1 lb of airflow = 1 mm of wastegate diameter.

 

OK R31 Nismoid, let's use your car as a discussion starter.....

 

300 rwkw = 480 bhp

480 bhp = 44 lbs of airflow = 44 mm wastegate

Now if you want to run 20 psi, then that's statistically the right size wastegate.

 

My experience indicates that to get 300 rwkw out of a GT30 you would need to run around 1.5 bar (22psi). So using the draft formula...

44 / 22 X 19 = 38 mm.

 

So based on the 75% success rate of the formula in the samples so far, I would say a 38 mm wastegate would be the go.

[stprasinz]

Ok I should have said not as impotant. there are pulses etc that do come into play. but these are also budget built parts. these are not harmonic tuned peices that squeze the last 1/10 of a hp. they are supposed to give a good bump in hp. And still no the equal length is not as important in a turbo car... the pulses are dampened by the turbo, and many other things.. the torques is there by the back pressure.. Also I hope you are running a torque tube off your wastgate. and the wastegate is centrally located.

 

but any way..till next time...

[steveosupremeo]

if you look in the latest issue of project car, they talk about the tomei header they use on an SR20 and its not equal length, saying its only needed in maximum effort race motors. it does however divide the pulses for adjacently firing cylinders. and its SS. I'm down with closer to stock location so that more people could just "drop it in". as close to stock thickness on the flange as they can make as well. or if not maybe weld tabs to meet the thickness of the intake manifold for the washers.

[jeffer949]

Ok something we need to get nailed down is what size we want the primaries. I heard someone say "1 5/8" would that be good or idk Give me some ideas. im getting a manifold shipped off to him for mock up.

[savageskaterkid]

1 and 5/8 sounds good to me. Although I haven't measured the stock one before.

[stprasinz]

I would think 1 5/8 would be minimum.small blocks use 1 5/8 on mild modified up to 350 hp and thats 8 cyl. flowwing that much air. were a 6 cyl. flowwing as much air as a small block.... so I would say 1 7/8 myself... but prob..ably a comprimise would be 1 3/4.... but I will still be a taker even at 1 5/8

[savageskaterkid]

I mean, you can't go too big, gotta measure the ports first, I don't remember what they are, anything bigger is just overkill and so much harder to make.

[Nigel]

I've read through the chapter on exhaust systems in the book "Street Turbocharging" by Mark Warner, and below are highlights from the section on manifold design. He covers log and tubular style, and since ours is likely going to be a combination of the two for practical reasons, I've included excerpts about both:

 

LOG MANIFOLDS

 

Log manifolds sacrifice some performance potential, but for moderate-boost street engines they can perform within 75% to 90% as well as a purpose-built individual runner manifold.

 

When designing a log manifold, it is best to avoid sharp, right-angle feeds of the individual ports into the log. It is better to angle, or sweep the port feeds into the log as gradually as possible. It is also important to keep the flow moving in only one direction: toward the turbine. Anytime the flow from one exhaust port "tee's" into the log at a right angle, or is pointed back in a direction that is the opposite of the flow from another port, the result will be a loss of efficiency.

 

TUBULAR MANIFOLDS

 

When designing a tubular manifold, the goal is to keep as much thermal and kinetic energy in each exhaust stream as possible. Short tube lengths are better than long ones. A minimal number of bends is also preferred. Where bends and turns in the tubes are required, keep them gradual and smooth. Large radii are better than small radius bends. It's also important to keep the individual tubes as equal in length as possible. The closer they are to each other, the faster the turbine spool-up will be.

 

Note, too, that the individual tube diameters on a properly engineered manifold tend to be slightly smaller than on a similar NA engine. Usually the cross sectional area of the exit port on the cylinder head is a good starting point for sizing the runners. For tubular manifolds, it's better to err on the small side, which will maintain gas velocity and reduce the exterior surface area, helping to minimize heat loss.

 

It's better to group cylinders that are far apart in the firing order together in the collector.

 

Nigel

'73 240ZT