Mandrel bent X-Over? Mandrel Downpipe? (feeler thread)

[tyroelite]

any idea how long it would take?  just wondering how long i'd be w/o a car while a x0ver is being made from the stock one.

[RedZMonte]

any idea how long it would take?  just wondering how long i'd be w/o a car while a x0ver is being made from the stock one.

2-3 days plus shipping time. so with shipping ~5business days maybe faster.

Shane

[god910]

Well, Shane, I'm out on the X-over because I don't have a core.  And I'm not chopping up one of my Jeff M's  :shock:.  I do have a question about the DP though.  Are you using stock flanges for it, or do you have an aftermarket supplier of them?  I have been looking at my extra DP, and it looks like I can grind the welds off the flanges (that would separate the SS flex braids), but I don't know what is under them.  Anyone know?  Since the 5 speed is a track/RARE weekend runner I am thinking of making a 3" DP and dump it behind the Driver front tire.

[RedZMonte]

Let me check into flanges. I might be able to get some made. its going to make it cost more obviously but you won't need a core.


as for the downpipe i have all the flanges and everything i need for it. unless your running a larger turbo i don't think you need a 3" downpipe. if you want a 2.5" mandrel dump i can probibly make one. your best bet is to just get the one i make now and unbolt it from the cat, that will be just as good if not better because you don't need to swap the pipe at the track, just undo the 2 bolts.

OR another option is to add a cutout into the downpipe and unbolt the flange at the track with the wing nuts.

Shane

[twinturbosedan]

Shane - i'm a little confused about the downpipe you sell.  does the downpipe you sell go from the turbine housing to the cat, or is it just the 'S' shaped pipe between the cat and the part of the downpipe that has the SS braids on it? (like in the pic on your website)  in other words, does your downpipe replace this part:

http://turbosedan.com/turboste/DSC00901.JPG

[Invasion1]

I believe its the part after that section in your picture josh.....

where that piece connects to the actual Exhaust pipes that hug the frame and bend towards the Cat.

Dave

[RedZMonte]

I believe its the part after that section in your picture josh.....

where that piece connects to the actual Exhaust pipes that hug the frame and bend towards the Cat.

Dave

correct

[twinturbosedan]

ok, just wanted to be completely sure.

[RedZMonte]

FYI: I can make the turbo flange but and i just orderd 2 flanges for Manifold to x-over to see if they will work. i want OEM style ones so they won't bend over time.

Shane

[ReallyFastZ24]

I've tried getting hold of Jeff M for weeks now, can't even get any more than the automated response.  How much for one of the pipes reman'd?

-- Lee

[Invasion1]

1.75" Mandrel bent X-over w/ ss braided flexes $375 Shipped +stock x-over
2.5" mandrel downpipe With SS Braided flex. $155US Shipped

shane

Prices......

[Gearhead43]

Jeff M is right about a 3" pipe being overkill on a small V6. These V6's, (even the turbo'd ones) need a little amount of BP to help scavange the exhaust gases.  And velocity of the gases has alot to do with it.  Becuase it helps PULL burnt gasses out of the system.

 For example, Say you have 2 1/4" pipe with 500 CFM of exhaust gas flowing thru it... The velocity of the gas will be constant at so many feet per sec. Now if you replace that 2 1/4" pipe with a 3" pipe, you are still moving 500 CFM of exhaust gasses. BUT the velocity of the gasses slows down. If you replace a 2 1/4" pipe with say a 1 3/4" pipe, again, you are still moving 500 CFM of gas but the velocity of the gas will increase.

Thus small pipe = higher velocity
large pipe = lower velocity

The size of the pipe will also be a factor in the amount of backpressure, But keep in mind that bends in the pipe also  fit into the BP equations.

 Too small a pipe will be too restrictive, while too big a pipe will allow too much loss in BP...

 :arrow: Bigger is not always better :!:

[skalor]

Jeff M is right about a 3" pipe being overkill on a small V6. These V6's, (even the turbo'd ones) need a little amount of BP to help scavange the exhaust gases.  And velocity of the gases has alot to do with it.  Becuase it helps PULL burnt gasses out of the system.

 For example, Say you have 2 1/4" pipe with 500 CFM of exhaust gas flowing thru it... The velocity of the gas will be constant at so many feet per sec. Now if you replace that 2 1/4" pipe with a 3" pipe, you are still moving 500 CFM of exhaust gasses. BUT the velocity of the gasses slows down. If you replace a 2 1/4" pipe with say a 1 3/4" pipe, again, you are still moving 500 CFM of gas but the velocity of the gas will increase.

Thus small pipe = higher velocity
large pipe = lower velocity

The size of the pipe will also be a factor in the amount of backpressure, But keep in mind that bends in the pipe also  fit into the BP equations.

 Too small a pipe will be too restrictive, while too big a pipe will allow too much loss in BP...

 :arrow: Bigger is not always better :!:

We have plenty of backpressure, in fact we have too much backpressure.  

Let's generalize and say we have twice as much backpressure as boost(most factory turbo cars have around a 2:1 ratio).  So, if you have a TG chip and are running around 11-12 psi then we have 22-24 psi of backpressure between the exhaust valves and the turbine.  This a big problem bacause of exhaust gas reversion.  The exhaust backpressure far exceeds the intake manifold pressure and there is actually reversion of exhaust gases into the intake manifold.  This is why most turbo cars do very well with a factory cam, because factory cams don't have a lot of valve overlap so this fights the exhaust gas reversion. So if we have 22-24 psi of backpressure before the turbo and then another 4-5 in the turbo-back exhaust then that would make it 26-29 psi of total backpressure.  So, why not just put on a huge turbo-back exhaust and get rid of the extra 4-5 psi.  Most aftermarket turbo companies that make exhausts use 3" or as big as will fit.   :twisted:

Now, will this make our cars spool faster.  Well, it should but the problem is that our boost is computer controlled over 4 psi.  Our turbo spool-up ~4 psi(since that is our wastegate actuators pressure setting) and then it's controlled via the computer using the wastegate solenoid.  The solution is to simply run a manual boost controller, but it's comes at a price.  The computer can pull boost down to ~4psi in an excessive knock situation, possibly saving your engine.  8)

[idbeast]

I have a couple of questions/comments...
Do the billows you are using have an insert, or are they rippled causing the exhaust to swirl, disrupting the smooth Exhaust flow. :shock:  :shock:
Are you using the JCWhitney billows which have mild steel flanges instead of stainless attachment flanges??? Your welds look extremely large, tending to make it look like dissimilar metals...
:shock:  :shock:  :wink:  :drinking:

[RedZMonte]

3" downpipe is overkill and will not gain you anything on our little turbos. 2.5" is more then sufficent for most turbos, again unless your running insane ammount of boost ~24+. Our turbo's will not be efficent most likely after like 12-14psi. If you run enough boost to require a larger downpipe then 2.5" then you are going to need a larger turbo before anything.

i use SS flexes. Not from JCW. It is all made of I belive T409 Stainless. mine is Mig welded. The ones i will be making i told my guy i wanted tig welded. so the welds will be nicer then what you see here.

Shane