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Discussion Starter #1
I'm about to get ready to fabricate my dump pipes for my 408. I'm using 2 X GT35R's which have a 3" outlet. I'm going to do everything I can to make the dumps out of 3" pipe, but it's so tight near the fire wall so am considering stepping down to 2.5".

How much effect will this have on my combo?

The driver's side will be very close to my brake booster and I'm worried it will give me problems...

Pic of combo is attached
 

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My 331 has twin GT35's.. My Downtubes are 2.5" that expand to 3" pipes to the Mufflers which are 2.5" with Tailpipes.. It's a Dynomax Catback kit I got WAY back.. I didn't want to spend the money for a 3" kit and I wanted a stock look, so I reused what I had.. So yeah, 2.5" to 3" and back down to 2.5" I put V-Bands on everything. I put Flexpipes and some Bullet Mufflers into the Ultraflo's, so yes 4 Mufflers. It positively does not drone, but it's not super quiet either like you might think.

The Driverside is real tight by the Steering Shaft. I had to get a shorter bolt that connects the SS to the Steering Wheel because it would rub on the pipe.. It's a pain to remove that DT because you must take off the Steering Shaft to get it off because it's so tight by the Booster and the Valve Cover. Maybe yours will be different.

But, I think if you went 2.5" to 3" you would be just fine with the bigger motor.. You have an easy 1000hp.

https://c1.staticflickr.com/5/4015/35575918081_e7730a3ffa_h.jpg
https://c1.staticflickr.com/5/4214/35575852981_c3cf10a378_b.jpg
https://c1.staticflickr.com/5/4230/35575850801_13601d3bb5_b.jpg





 

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Discussion Starter #3
Cheers mate! Appreciate your input. I was reading your build many many moons ago and plan to refer to it for the plumbing of the turbos.

What size outlets were on your turbos? Are yours 3" as well?

In my mind, if the turbo has a certain outlet size then it needs that size at minimum to prevent any unwanted back pressure..

Then again, it may be marginal and I wouldn't even notice...
 

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Discussion Starter #4
Pic of drivers side near the booster. Some how need to sneek 2.5" or 3" pipe down there. That booster is a plastic one but I will be putting in a steel dual diaphragm one which is a little smaller
 

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Your Turbine Housing is a bit different from mine and looks like it expands from 2.5" to 3". Oddly enough, mine came with a bolt on flange that expands to 3" but for a V-Band connector.. Your Turbine Exducer Diameter is 62mm, same as mine so the wheels are the same. I don't have any problems making power with a 2.5" DT Pipe. I don't think there would be a problem for you either, but if you can fit a 3" that would be cool.


 

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Unless it's going to be a race car I say build it to fit your needs. It's a PITA fighting the little things when building or working on it so design it so it's comfortable to work on. Besides it's a turbo car if you want more power just turn up the boost..;)

ks
 

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Discussion Starter #11
Your Turbine Housing is a bit different from mine and looks like it expands from 2.5" to 3". Oddly enough, mine came with a bolt on flange that expands to 3" but for a V-Band connector.. Your Turbine Exducer Diameter is 62mm, same as mine so the wheels are the same. I don't have any problems making power with a 2.5" DT Pipe. I don't think there would be a problem for you either, but if you can fit a 3" that would be cool.



Thanks Midnightlaundry, I will change out my booster for the smaller steel type then see how I go for space. At the moment I have 20mm gap from the plastic booster and a 3" pipe. The steel one might get me 30-40mm but even that might still get a little hot... Stepping down to 2.5 gives me an extra 11mm so 40-50mm clearance.

Sorry about all the metric figures. It's what we use down under 🇦🇺🇺🇸
 

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Discussion Starter #12
Unless it's going to be a race car I say build it to fit your needs. It's a PITA fighting the little things when building or working on it so design it so it's comfortable to work on. Besides it's a turbo car if you want more power just turn up the boost../forums/images/smilies/wink.gif

ks
Cheers Kevin. I agree, it's not hard to get caught up in trying to perfect a design for almost little benefits. Regardle of which way I go. It's going to be a PITA haha. These dump pipes will need to come off for jobs that require the rocker cover coming off, or even plugs and leads related tasks...

Yes, I should have tonnes of boost up my sleeves. Only planning on running low boost. It's a stock F4TE so it's the weakest link..
 

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Discussion Starter #13
Midnightlaundry- Shortly I'll be placing my waste gates. Are yours externally gated? Have you got a pic, if so?
 

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I have mini domes with 4psi springs.. I use Boost Control on the Computer to go up from there. There are tucked in and hard to see with the Motor in the Car. You can see them in this mockup pic. They have little turndown pipes the aren't installed in the pic but vent to air. The Car is basically open exhaust when they open up and is loud. It's like Jekyll and Hyde.. If you can, plumb the dumps back to the Down Tube so the car is quiet if you desire.

https://c1.staticflickr.com/5/4128/35706677415_7784e489fd_o.jpg
https://c1.staticflickr.com/5/4134/35706675065_b833f7966d_b.jpg
https://c1.staticflickr.com/5/4153/35706674275_76a0d1e50a_o.jpg





 

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Cheers Kevin. I agree, it's not hard to get caught up in trying to perfect a design for almost little benefits. Regardle of which way I go. It's going to be a PITA haha. These dump pipes will need to come off for jobs that require the rocker cover coming off, or even plugs and leads related tasks...

Yes, I should have tonnes of boost up my sleeves. Only planning on running low boost. It's a stock F4TE so it's the weakest link..
I'd definitely go with 2.5" or maybe split the difference and fab up 2 3/4" if you're concerned about power but you will never notice the difference in power. Do yourself a favor and give yourself all the room you can get. I'm running 3" dp's into full length 2.5" exhaust and feeding into three mufflers plus through a 4R70, making over 900hp.

ks
 

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Discussion Starter #16
I have mini domes with 4psi springs.. I use Boost Control on the Computer to go up from there. There are tucked in and hard to see with the Motor in the Car. You can see them in this mockup pic. They have little turndown pipes the aren't installed in the pic but vent to air. The Car is basically open exhaust when they open up and is loud. It's like Jekyll and Hyde.. If you can, plumb the dumps back to the Down Tube so the car is quiet if you desire.

https://c1.staticflickr.com/5/4128/35706677415_7784e489fd_o.jpg
https://c1.staticflickr.com/5/4134/35706675065_b833f7966d_b.jpg
https://c1.staticflickr.com/5/4153/35706674275_76a0d1e50a_o.jpg





Thanks heaps again for the pics mate! Very helpful!

I didn't know you could use a low lb spring and then a controller to fine tune. Might look into it. I may be using turbosmart 60mm gates as o intend to run low boost. Apparently you need a bigger gate for low boost.

Also I think I read you need to place the gate port at 45 from the main stream. Yours look about 90? Did you have any boost issues?
 

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Discussion Starter #17
Cheers Kevin. I agree, it's not hard to get caught up in trying to perfect a design for almost little benefits. Regardle of which way I go. It's going to be a PITA haha. These dump pipes will need to come off for jobs that require the rocker cover coming off, or even plugs and leads related tasks...

Yes, I should have tonnes of boost up my sleeves. Only planning on running low boost. It's a stock F4TE so it's the weakest link..
I'd definitely go with 2.5" or maybe split the difference and fab up 2 3/4" if you're concerned about power but you will never notice the difference in power. Do yourself a favor and give yourself all the room you can get. I'm running 3" dp's into full length 2.5" exhaust and feeding into three mufflers plus through a 4R70, making over 900hp.

ks
Thanks again for your help here!

I think you've won me over and I'm going to go the 2.5". I'll see how much smaller my steel booster is, and make the call!!

Wow your making good power. Ive been told I can make 4 figures too, but I'm worried about my block!

As for material... Should I go carbon steel dumps and get them ceramic coated? Was thinking stainless but I'm not sure if you can coat them, and then they will look just like CS if they are coated ..

Does one hold heat more than the other?
 

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Thanks again for your help here!

I think you've won me over and I'm going to go the 2.5". I'll see how much smaller my steel booster is, and make the call!!

Wow your making good power. Ive been told I can make 4 figures too, but I'm worried about my block!

As for material... Should I go carbon steel dumps and get them ceramic coated? Was thinking stainless but I'm not sure if you can coat them, and then they will look just like CS if they are coated ..

Does one hold heat more than the other?
My block is also my limitation (iron Cobra block) and I'm pushing it to the limits but it should be fine.

If you can afford SS I would go that route. It's a lot more $$ but if you can afford it then it will last longer especially the pipes pre-turbo. They won't ceramic coat the inside of the pipes pre-turbo in case it flakes off. I went mild steel on everything and ceramic coated inside and out. But something odd I noticed one day was that rust was showing on the inside of the pipes - more like rust bubbles that I could wipe off with my finger. Not sure how this can even happen and maybe it was from the pipes pre-turbo rusting, I dunno. SS was waaay out of my budget otherwise I would have gone that route.

Not sure about the heat retention, etc. I hear a lot on the forums but the way I look at it: HOT is HOT. Exhaust can get 900* so unless the pipes can stay several hundred degrees cooler then it doesn't matter to me. If you need insulation then get the wraps and wrap the pipes. You will still want to ceramic coat the outsides before putting on the wraps otherwise the wraps can hold moister and rust the mild steel pipes from the outside.

Call some ceramic coating companies and see if they have an issue with coating SS.

Here's my Bling:



ks
 

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Thanks heaps again for the pics mate! Very helpful!

I didn't know you could use a low lb spring and then a controller to fine tune. Might look into it. I may be using turbosmart 60mm gates as o intend to run low boost. Apparently you need a bigger gate for low boost.

Also I think I read you need to place the gate port at 45 from the main stream. Yours look about 90? Did you have any boost issues?
No boost issues... I have the car setup for boost by gear. 1st and 2nd are almost useless with street tires on the street. I can blow the tires off in 2nd by just putting the pedal down on spring with 4 psi. So I only run spring pressure in 1st and 2nd because that's as low as I can go without it being a complete burnout fest.. 3rd gear I can bring in more boost.

Check out Nelson for some more ideas.


Check out the Wastegate setup on this one. They have the dumps plumbed to the Down Tube..

 

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Discussion Starter #20
Thanks again for your help here!

I think you've won me over and I'm going to go the 2.5". I'll see how much smaller my steel booster is, and make the call!!

Wow your making good power. Ive been told I can make 4 figures too, but I'm worried about my block!

As for material... Should I go carbon steel dumps and get them ceramic coated? Was thinking stainless but I'm not sure if you can coat them, and then they will look just like CS if they are coated ..

Does one hold heat more than the other?
My block is also my limitation (iron Cobra block) and I'm pushing it to the limits but it should be fine.

If you can afford SS I would go that route. It's a lot more $$ but if you can afford it then it will last longer especially the pipes pre-turbo. They won't ceramic coat the inside of the pipes pre-turbo in case it flakes off. I went mild steel on everything and ceramic coated inside and out. But something odd I noticed one day was that rust was showing on the inside of the pipes - more like rust bubbles that I could wipe off with my finger. Not sure how this can even happen and maybe it was from the pipes pre-turbo rusting, I dunno. SS was waaay out of my budget otherwise I would have gone that route.

Not sure about the heat retention, etc. I hear a lot on the forums but the way I look at it: HOT is HOT. Exhaust can get 900* so unless the pipes can stay several hundred degrees cooler then it doesn't matter to me. If you need insulation then get the wraps and wrap the pipes. You will still want to ceramic coat the outsides before putting on the wraps otherwise the wraps can hold moister and rust the mild steel pipes from the outside.

Call some ceramic coating companies and see if they have an issue with coating SS.

Here's my Bling:



ks
Oh your bling looks on point!

I will definitely be calling up a coating place and asking about SS vs CS.

I'm also not really a fan of the heat wrapping, it can look tacky sometimes. Especially when you've taken so many extra steps to make the engine bay look clean and tidy.

My pre turbo is already fabbed from a mix of SS and CS. I bought a cheap set of mustang turbo manifolds and modified them to suit.
 
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