[reboticon]

No. The compressed air is going to the same throttle body. There will just be more lag with one further away (how much is yet to be seen). There's a reason that people buy a pair of headers to gain power and keep their engine running smoothly. When you have two different exhaust gas paths with differing flow rates/velocity you going to have different combustion situations therein, which is not ideal.

You may be right, but your reasoning is off. If he has equal length runners to the X-pipe after the headers and before the turbos, then the combustion situations at each cylinder are equal, assuming both turbos are feeding one common throttle body.

After the crossover point, the exhaust is going to take the path of least resistance, which would be the closer turbo, then a fraction of a second later hit the other turbo since the friction of the first turbine causes resistance.

So what im saying is, i would understand if each head fed one turbo, but with an X-pipe, or both heads feeding into a Y and then branching off to each turbo as a Y (essentially making a stretched X), it seems like the lag could mimic the idea of one large and one small turbo. Basically one kicking in low in the rpms, and the other higher.

Like i said, i may be totally off here, just want to know why:thumbsup:

 

[Telion]

This makes things interesting, these are from a Porsche 996 years 99'-04

it certainly looks close.

 

[DandDEE]

hope that works ima watch just to see if i can do the same thing

 

[Dethred]

You may be right, but your reasoning is off. If he has equal length runners to the X-pipe after the headers and before the turbos, then the combustion situations at each cylinder are equal, assuming both turbos are feeding one common throttle body.

After the crossover point, the exhaust is going to take the path of least resistance, which would be the closer turbo, then a fraction of a second later hit the other turbo since the friction of the first turbine causes resistance.

So what im saying is, i would understand if each head fed one turbo, but with an X-pipe, or both heads feeding into a Y and then branching off to each turbo as a Y (essentially making a stretched X), it seems like the lag could mimic the idea of one large and one small turbo. Basically one kicking in low in the rpms, and the other higher.

Like i said, i may be totally off here, just want to know why:thumbsup:

I was under the impression that the principles of velocity and sonic tuning still applied, even when a barrier such as a turbine enters the mix.:hide:

 

[Dethred]

This makes things interesting, these are from a Porsche 996 years 99'-04

it certainly looks close.

99-04 Porsche 996 Non Turbo Stainless Steel Performance Headers - $300.00

~$300.

OBX are on Ebay for a similar price. It's probably going to be more of a headache hacking up manifolds that might not work and will be more work either way...

 

[Telion]

I found them for 100.00 shipped

 

[Telion]

Ok the porsche ones are definately out they look like they A. facing forward with the collector on the lower part will hit the alt and the PS. and B facing forward woth the collector on the topside won't clear the valve covers.

 

[reboticon]

You may already know someone local who could make you some, this site lets you fill out specs and gives you an estimate. CES - Custom Headers

 

[Telion]

I have decided on the 350z headers then if I need to re-work them I will

 

[Dethred]

GIT R' DUN!

 

[Telion]

Ok it was difficult to make the decision to spend 100.00 on an item that is in question as to whether or not it will work but I think somehow it either will or will be forced to work lol. But I have to answer the question that many of us wonder, just how close are these?

I will know very soon, let us pray :angel:

 

[DandDEE]

now the true tests begin good luck ... alot of blood sweat and tears are gonna shed in this project aren't u glad u have us

 

[Telion]

Indeed!

 

[guest]

you do know you have to chuck those on for a NA perspective right? I'm thinking it may have to be forced a wee bit due to the fwd layout, damn engineers. As for praying, let's hope it doesn't take the biggest hammer you have

 

[GrumpySteelMan]

DandDEE - you aren't alone, this thread makes my brain hurt. Its funny the difference between one of grumpys posts here and in the lounge. Both of them make my head hurt but from different spectrums

What is that supposed to mean?

Well, a straight six is always going to have the exhaust ports on the same side though, right?

I couldn't imagine doing it any other way.

Question. I realize that on a racetrack, having both turbos as close to the ports of each head would be the best for optimal performance. In this case though, assuming he was going to drive it on the street, couldn't it actually be helpful to have one turbo further from the exhaust than the other? When i think of it, I see one turbo spooling earlier in the RPMs than the other. Wouldn't that actually help to increase the hp throughout the powerband, instead of kicking it all on at once? I used to drive my 7.0L on the street, and that much torque can get frustrating. Or have i got this figured wrong?

You're thinking about a sequential turbo setup. A very effective layout, but for all intents and purposes this will be a 'biturbo' setup. The differences between piping distances will have a negligible effect.

No. The compressed air is going to the same throttle body. There will just be more lag with one further away (how much is yet to be seen). There's a reason that people buy a pair of headers to gain power and keep their engine running smoothly. When you have two different exhaust gas paths with differing flow rates/velocity you going to have different combustion situations therein, which is not ideal.

If you think about the volume of the entire intake (pipes, i/c, etc) the extra distance is pretty insignificant. The exhaust side matters, but until you start causing large thermodynamic differences...like a turbo 12" from the head, and a turbo 12' from the head...you are unlikely to have any serious issues.

Thanks for understanding the need for balance on the exhaust side. :thumbsup: Although I think you oversimplified your example.

Ok I picked up a gasket from an 05' 350z and it looks fairly promising the shape and size of the holes are virtually identical to our cars. The difference as we pretty much knew was in the spacing between each port. in order to best determine the spacing I centered the two center holes which line up nicely and measured the variance on the outer holes. Each outer hole on the 350z is a hair over 1/2" wider than the Legends gasket. So I am thinking this could be worth a shot. At the price these are available for it would cost more than that just to buy the material for a custom set to be made not including labor, and even better I will not have to hack up my OBX headers. One thing I do need to consider though is the amount of stress that 1/2 would cause. I think it would be best to heat them up and correct the variance. here's the pics.

The stress at the collector won't be the biggest issue looking at the design. I would consider enlarging the outside manifold bolt holes to account for the expansion of the metal...remember stainless experiences heat expansion about 2x what mild steel does.

Heat bending is probably an ok idea, although personally I'd cut them apart and 'rebuild them' with some extra pipe.

Most importantly I'd cut the 350Z flange off, bend (or rebiuld) the pipes to the proper spec, and then have the pipes decked on a milling machine before I welded the Legend flanges on, and then have it decked again after welding. I suggest this because you'll want those joints and welds to be very strong, and you'll want to minimize the effect welding has considering warpage on the final product.

 

[reboticon]

For your next project... I want you to turn a legend into a transformer:bowdown:

 

[GrumpySteelMan]

So what im saying is, i would understand if each head fed one turbo, but with an X-pipe, or both heads feeding into a Y and then branching off to each turbo as a Y (essentially making a stretched X), it seems like the lag could mimic the idea of one large and one small turbo. Basically one kicking in low in the rpms, and the other higher.

Like i said, i may be totally off here, just want to know why:thumbsup:

You're totally off. You're still splitting the heat between them. The only sense to a big/little turbo would be in a sequential setup, i.e. the turbines are in series not parallel.

If they were in parallel, then the larger turbo would still only be getting a portion of the exhaust energy...basically wasting it until the smaller turbo had spooled up and there was enough waste heat to drive it also. You'd also have the problem of bleeding exhaust from the small turbo to maintain a reasonable boost pressure which would also retard the larger turbos performance.

 

[reboticon]

Ya but i was saying that two of the same turbos would seem to mimic the effect of a large/small. It seemed like, in essence, your post agrees that it would, It would just be so ineffecient (from the wastegate opening on the closer turbo), as to not being a practical consideration for application.

Im hoping thats right, because then it all makes sense in my head, otherwise im confused again:bigok:

I want an update from Telion or im starting work on my transformer.

 

[GrumpySteelMan]

You're still confused...unless the mimicry is that the turbo system would suck ass until both turbos spooled.

The performance would be degraded if there was a significant difference in distance between the two turbos in a biturbo system. You must realize that the 'twin' turbos are each about half the size of optimal (even here) to get the car boosted at a given flow rate. If you've only got half the flow rate while you're waiting for the other turbo to come up then you're way out of the efficiency range of the first turbo, making tons of heat and not much power. This is not to mention that the first turbo, sharing a plenum with the second could actually stall the compressor on the second turbo because the boost pressure on the intake side could overcome the power and inertia being exerted on the turbo with the less efficient positioning.

So:

big/little is most effective in sequential (series) for maximum effort

little/little is most effective in parallel for maximum effort

little/little sequential (series) would have very fast boost response with a reduced total flow ability. This is probably what you're really thinking about with your train of thought, but you've got the exhaust paths wrong to make it work.

 

[Telion]

Sorry for there not being too many posts lately I will try to update with some progress and pics tonight. Grumps your train of thought (in a much more scientific manner than mine) is the same as mine. I think a small set of twins will be just fine for now, and I will upgrade upon continued success, this is a learning process for me. I have decided to further entertain the relocation of the battery to the trunk and am currently working on setting it up as such. In addition the intercooler piping has come in and as predicted I am still a few pieces short to complete that but I wanted to get started to see what else I would need. hopefully the 350z headers and piping will be here by this weekend and I can either cry or celebrate . I am however still convinced that I (with help) can get it to work one way or another.

A couple things anyone know a great place online for 0 gauge wire? how many feet I will need to get the battery to teh trunk for + & - terminals?

And is anyone currently running a 3" muffler (now I know why DV8 pulled his whole exhaust line, that took me long enough to figure out lol).

Oh side note. many things I have put together in my head as far as spacing and placement of stuff have changed drastically so if you do this, get an idea, set a budget, (knowing you will exceed it), get the stuff then work through your ideas with the actual stuff in hand. I here captain obvious in the back of my head lol sorry!