OneBadTA

I understand and see that but what STS is saying is that using there method of a smaller exhaust housing will spool the turbo fast and will have less backpressure than the conventional setup with a large exhaust housing and make close to the same amount of power. I dont wanna knock Zombie because i know he has a badass setup but i wonder if all the header wrap is neccessary for the rear mount when all you can do is run a smaller turbine housing and reach the same results. This is going off of what STS says though.

mike13

iTrader: (27)

Header wrap is a big help, running a smaller A/R to achieve better spool should be a last resort. I know from experience, as I have a smaller turbine housing as a paper weight from a tc76.

OneBadTA

The theory is the loss of heat causes a loss of backpressure and velocity so a smaller a/r needs to be used to raise the levels back to normal. The heat has nothing to do with the spool. It's the velocity and backpressure that does it. That's why a smaller a/r would bring the velocity higher making the spool responsive and make great power. The big problem I see with header wrap is moisture gets in the wrap and rots the exhaust away unless it's stainless. The wrap is the bandaid for not having the correct sized housing. Sorry if I'm agreeing with STS but they provide and prove the theory on how to correctly use the setup.

OneBadTA

*double post*

OUTLAWZ RACING

iTrader: (9)

The heat has alot to do with spool. You cant take a car run it for 30 sec and go wot and expect to get full boost. The trade off of a tiny ar is quick spool with no top end due to back pressure, remeber the biggest restriction in the exhaust is the turbo. I agree on velocity in the exhaust for a rear mount. You dont need 4 inch exhaust to run a but mount, you will get more air to the turbo but at a slower rate and you may see a rise in back pressure. The header wrap works its not a bandaid I saw real world results by using wrap. When I was on the 67 trim no wrap I would have to run the car and go into boost several times befor I got my desired boost level and spool rate. With the wrap I let the car warm up and its ready hell even the tone of the turbo changed. Heat expansion is a great help on sts cars. Im not knocking sts theroy about heat in the pipe, but it just dosent seem right to keep that on the websight when the concept has been proven wrong. YES you want the maximum amount of heat enegery in the exhaust to spool the turbo, YES header wrap works.

OneBadTA

Exhaust velocity changes as the turbo is farther away. Its not cause it loses heat, its cause of the distance. You can change the velocity by changing the size of the header primaries and exhaust size. Too small of piping can hurt velocity as well as too large of piping. You gotta figure out what works best with the setup. The turbine housing does the same thing. A rear mount sees lower velocity through the exhaust than a front mount would. Seeing as the rear mount is lower, you need a smaller turbine housing to bring the velocity back up to working levels. It wont increase backpressure any higher than the front mount setup. What do you think happens when you put too big of a turbine housing on a front mount setup? The heat it still there but the larger housing lowers velocity causing that lag till you reach a high enough rpm where the velocity increases to spool the turbo up. Same goes with a rear mount. Its all about the velocity, not the heat. Heat helps but not the important part with a properly sized turbine housing.

mike13

iTrader: (27)

Heat is a huge part of the equation in turbo theory, Yes header wrap can cause metal to become brittle from the heat. It is not a bandaid for the correct A/R housing. As far as STS providing and proving the theory. This is the same company that argued for years that you didn't need a intercooler and the turbo tubing acted as a subframe connector.

mike13

iTrader: (27)

Velocity changes becauses it looses heat, it's the same theory used for steam, the superheated molecules from the exhaust take up more space creating more pressure when not having infinite room to expand creating more velocity when escaping. As the gas cools the molecules become less active requiring less space which causes a loss of velocity.

Same theory in reverse on why you run a intercooler.

OneBadTA

http://www.tercelreference.com/terce...st_theory.html

This is what i can find about Turbo Exhaust Theory.

OneBadTA

Ah ok, i understand now. Anyone know the EGT at the manifold and back where the turbo would be? Coated and uncoated?

OUTLAWZ RACING

iTrader: (9)

My egt where close to 300 degrees full tilt on the highway. I melted that cheap *** egt guage tho lol. But I agree on proper ar sizes with u good example is a t88 on a 1.4ltr motor dosent matter how hot it gets you will never spool that turbo to its effenicy range.

OneBadTA

Were all on the same page now. Just a little meeting of the minds. Lol. I only pressed the topic so heavily cause im looking at doing a rear mount and wanna understand everything before jumping into it.

mike13

iTrader: (27)

Stick with what has already been proven when doing a rear mount. Alot of us have already made the mistakes and can save you the headache..

If you need any help or have questions do a search lots of info and ask for help if needed.

OneBadTA

Forums are alot of hearsay so i dont believe much of it unless its proven by theory, numbers, and providing proper facts. Thats why i asked my original question. Our discussion brought out new things to look at and improved on what has already been done. From what i learned, no matter what, your gonna lose exhaust velocity by the time it reaches the turbo. Wrapping or coating will help alot but velocity will still fall. Something around a .70 or .81 Turbine Housing should help keep velocity higher without creating enough backpressure to effect top end numbers. Anything smaller and backpressure will kill numbers and anything larger will make for more lag and loss in response.

OUTLAWZ RACING

iTrader: (9)

.81 hot side is what I run and spool up is great, 3.4k on gts 76 4xx ci

OneBadTA

Ill be sticking with a 350 or 355. .70 would probably be better for me because of the smaller displacement not putting out nearly the exhaust velocity of what your 4xx does.

mike13

iTrader: (27)

No!!!!! don't do it, I have a TC76 and started with a .68a/r the housing is to restrictive, here's some examples to help.

I bought a tc76 with .68 ran it for a few months and realized it was way to restrictive even for a 346. The .tc76 w/.68 is common for guys running twin turbochargers. I now have a .96a/r

The upgraded turbo for the sts is the T67 w/.81 a/r. It's not a apples to apples comparision just an example.

A super nice turbo combination is the TC76 with .81A/R if your starting with a close to stock motor and it allows you to have lots of room to grow (heads,cam,etc)

I have a .68 from my TC76 sitting in my garage, the $200 it cost me is $200 worth of knowledge you get for free.

toddcod

Selling 99 SS. I got a C4. As well as my older brother.

I was selling the camaro to my little brother (basically giving), and my older brother gave him the option of his WS6 6 speed or my 99 SS.

So now the Camaro is finding a good home. To recoop cost for the WS6.

And his procharger is going on my 92 LT1, and my sts kit is going on his 91 L98 C4.


I can't wait for boost. I have to do my homework on the tunning side!

It will be different being on the opposite side. I like turbo's and he likes Superchargers.

Should be fun.

JoshuaGrooms83

iTrader: (2)

i know old thread lol but what wire exactly?
was it grey one? im trying to figure out what wire to tap into instead of running a stupid long wire to the PCM like sts does. im doing a custom rear mount. heres a schematic i dug up to help
https://ls1tech.com/forums/17177393-post207.html