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Old 02-10-2016, 11:19 PM   #181
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Downpipe made. This part sucked! Gotta pull it and the turbo and build the little pipe for the external gate next. Ended up pie cutting a mandrel bend and making a 1.6-1.7" radius 3" bend. Had to be a tight radius to clear everything. Also shortened the heater hose some more to get it further out of the way.























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Old 02-11-2016, 02:46 AM   #182
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Made a piece to connect the external gate back into the 3" downpipe. Took longer than I hoped... But it's made now. I got a list of 40 things left to do. Got two done in last 3 hours!

I kinda doubt it's going to be driving on Friday.... Most is little 10 minute items, but some is fab work. Still need exhaust with glasspacks, surface rear flange for big turbo. And fab a quick/dirty hotside intercooler pipe that will be temporary until my 2.5" mandrel bends arrive and I can make a nice one. And design/fab a mounting bracket for the remote oil scavenging pump. The rest is not as bad.

Why not, here's the list.

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Old 02-11-2016, 04:11 AM   #183
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STRAIGHT PIPE!

Edit: although my '84 5.0L Tbird with dual glasspacks set off so many car alarms ... was awesome.
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Old 02-11-2016, 05:09 AM   #184
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STRAIGHT PIPE!

Edit: although my '84 5.0L Tbird with dual glasspacks set off so many car alarms ... was awesome.
Haha. I'm scared it's going to be too loud already. Hoping I can get away with a couple glass packs and that's it. But my guess is that will still be way too loud. If it's too loud, getting a muffler in the back is going to suck...
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Old 02-11-2016, 06:32 AM   #185
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Two snails. I think it will be quieter than you are anticipating.
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Old 02-11-2016, 09:10 AM   #186
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Default Pat's Ebay Turbo Compound Boost Build

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Two snails. I think it will be quieter than you are anticipating.
Definitely this. Turbos absorb the individual pulses and quell resonance.
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Old 02-11-2016, 10:55 AM   #187
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I would remove any cat(s) between the two turbos unless you want to sacrifice the 2nd turbo for science

I also agree with these guys that the glasspacks will likely do nothing but add weight to your car
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Old 02-11-2016, 12:30 PM   #188
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If it were me, I would use a single oval muffler (magnaflow, likely) behind the last turbo and nothing in between them. Adding cat, glasspack (mass and heat absorption) will slow the response of the turbo enormously as well as put the second turbo in danger of ingesting muffler material and more importantly, cat substrate. It will be much quieter than you anticipate.
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Old 02-11-2016, 12:41 PM   #189
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Quote:
Originally Posted by vteckiller2000 View Post
If it were me, I would use a single oval muffler (magnaflow, likely) behind the last turbo and nothing in between them. Adding cat, glasspack (mass and heat absorption) will slow the response of the turbo enormously as well as put the second turbo in danger of ingesting muffler material and more importantly, cat substrate. It will be much quieter than you anticipate.
I should take a pic and post it. You all are pretty creative, maybe you can figure out where/how to package a muffler in the rear. I agree 100%, I'd rather have a magnaflow in the rear, and no glass packs between them. Let me take a pic and post it.

The cat is staying for emissions. It's a metal core cat, it has 1 year of daily driving / 120 passes at the drag strip so far, and the core looks great so far. Car won't pass emissions without a cat, so it's not coming off.
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Old 02-11-2016, 12:48 PM   #190
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Quote:
Originally Posted by patsmx5 View Post
I should take a pic and post it. You all are pretty creative, maybe you can figure out where/how to package a muffler in the rear. I agree 100%, I'd rather have a magnaflow in the rear, and no glass packs between them. Let me take a pic and post it.

The cat is staying for emissions. It's a metal core cat, it has 1 year of daily driving / 120 passes at the drag strip so far, and the core looks great so far. Car won't pass emissions without a cat, so it's not coming off.
Poast pic, we will halp.
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Old 02-11-2016, 12:57 PM   #191
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One more thing, what size is your primary exhaust pipe that goes between the first turbo and second?
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Old 02-11-2016, 12:58 PM   #192
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3" exhaust from little turbo to big turbo. Uploading pics.
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Old 02-11-2016, 01:05 PM   #193
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Quote:
Originally Posted by patsmx5 View Post
3" exhaust from little turbo to big turbo. Uploading pics.
Okay, I am going to try to help you make this not suck.

You are going to need to change the exhaust between the turbos.

Turbochargers derive most of their energy from heat, not the gases moving. To make this work effectively, you are going to have to keep as much heat and gas velocity as possible to that rear turbo. That means reducing the cross sectional area of the pipe, as well as heat wrapping or ceramic coating the pipe.

3" with a rear mount turbo is going to be awful for spooling the big second and completely wreck what you are trying to do. You need to do 2" or 2.5" at most. This is all coming from years of experience with rear mount guys in the area. Most of the 5.7-6.0L v8 guys run a 2.5" pipe from the Y, all the way to the rear mounted turbo.

The metal substrate cat is great, that will work fine and even if it fails, it willl unwrap and not break off and get sucked into the turbo.

Consider changing the exhaust diameter. With that small turbo alone, you would make around, what, 250 rwhp at most? Size the exhaust one to two steps smaller than that would require for this and you will keep a decent spool for the second turbo.
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Old 02-11-2016, 01:09 PM   #194
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Sorry pics are crap, sun is messing them up.

The V-band off the turbo is 3.5". I have a 3.5" to 3" cone to weld to it that is about 2.5" long.

So coming off the cone, I have 19.5" from the exit of the cone, to the center of the cutout on the bumper for the exhaust pipe exit.

From front to back, 18" from center of turbo outlet to bumper cutout.










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Old 02-11-2016, 01:09 PM   #195
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Quote:
Originally Posted by vteckiller2000 View Post
Okay, I am going to try to help you make this not suck.

You are going to need to change the exhaust between the turbos.

Turbochargers derive most of their energy from heat, not the gases moving. To make this work effectively, you are going to have to keep as much heat and gas velocity as possible to that rear turbo. That means reducing the cross sectional area of the pipe, as well as heat wrapping or ceramic coating the pipe.

3" with a rear mount turbo is going to be awful for spooling the big second and completely wreck what you are trying to do. You need to do 2" or 2.5" at most. This is all coming from years of experience with rear mount guys in the area. Most of the 5.7-6.0L v8 guys run a 2.5" pipe from the Y, all the way to the rear mounted turbo.

The metal substrate cat is great, that will work fine and even if it fails, it willl unwrap and not break off and get sucked into the turbo.

Consider changing the exhaust diameter. With that small turbo alone, you would make around, what, 250 rwhp at most? Size the exhaust one to two steps smaller than that would require for this and you will keep a decent spool for the second turbo.
Please explain to me how a 2" single exhaust pipe will not choke his setup when he's aiming for 400+ to the wheels.

Also please show me a v8 with rear mount running a single 2" exhaust pipe all the way to the rear

This does not even compute in my brain
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Old 02-11-2016, 01:15 PM   #196
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Quote:
Originally Posted by vteckiller2000 View Post
Okay, I am going to try to help you make this not suck.

You are going to need to change the exhaust between the turbos.

Turbochargers derive most of their energy from heat, not the gases moving. To make this work effectively, you are going to have to keep as much heat and gas velocity as possible to that rear turbo. That means reducing the cross sectional area of the pipe, as well as heat wrapping or ceramic coating the pipe.

3" with a rear mount turbo is going to be awful for spooling the big second and completely wreck what you are trying to do. You need to do 2" or 2.5" at most. This is all coming from years of experience with rear mount guys in the area. Most of the 5.7-6.0L v8 guys run a 2.5" pipe from the Y, all the way to the rear mounted turbo.

The metal substrate cat is great, that will work fine and even if it fails, it willl unwrap and not break off and get sucked into the turbo.

Consider changing the exhaust diameter. With that small turbo alone, you would make around, what, 250 rwhp at most? Size the exhaust one to two steps smaller than that would require for this and you will keep a decent spool for the second turbo.
I think the small turbo should make 300whp or so on its own, maybe 350. It's similar to a GT2871 in wheel specs but ebay so who knows.

I already bought all the stuff to make 3" exhaust, and already fabbed 3" from the small turbo past the 3" cat. So I'm going to go ahead and finish the 3" and see how it performs since it's almost done and I have the materials already.

I am going to wrap and shield the exhaust system. The cat is wrapped and shielded already.

If the big turbo spools by 5K that would be great. If it's worse, I'll probably try smaller exhaust as you say.
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Old 02-11-2016, 01:17 PM   #197
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Quote:
Originally Posted by 18psi View Post
Please explain to me how a 2" single exhaust pipe will not choke his setup when he's aiming for 400+ to the wheels.

Also please show me a v8 with rear mount running a single 2" exhaust pipe all the way to the rear

This does not even compute in my brain
The bigger turbo acts as a pusher to force the smaller one. If you can keep velocity up it doesn't seem to choke the rear mount v8 guys at all. In fact, the twin setup I helped build had a 6.0L with 2.5" pipes to each turbo in the rear and it made 650 rwhp on 15 lbs.

Most single rear mount GTO guys use a 2.5" single pipe and even the guy with the cheapest DIY setup ran 100-105 mph in the eighth mile.
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Old 02-11-2016, 01:18 PM   #198
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Quote:
Originally Posted by patsmx5 View Post
I think the small turbo should make 300whp or so on its own, maybe 350. It's similar to a GT2871 in wheel specs but ebay so who knows.

I already bought all the stuff to make 3" exhaust, and already fabbed 3" from the small turbo past the 3" cat. So I'm going to go ahead and finish the 3" and see how it performs since it's almost done and I have the materials already.

I am going to wrap and shield the exhaust system. The cat is wrapped and shielded already.

If the big turbo spools by 5K that would be great. If it's worse, I'll probably try smaller exhaust as you say.
Do all you can to keep heat in that pipe. Keep the cat close to the engine to keep it hot and don't add anything else to that pipe if you can help it.
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Old 02-11-2016, 01:19 PM   #199
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Quote:
Originally Posted by vteckiller2000 View Post
The bigger turbo acts as a pusher to force the smaller one. If you can keep velocity up it doesn't seem to choke the rear mount v8 guys at all. In fact, the twin setup I helped build had a 6.0L with 2.5" pipes to each turbo in the rear and it made 650 rwhp on 15 lbs.

Most single rear mount GTO guys use a 2.5" single pipe and even the guy with the cheapest DIY setup ran 100-105 mph in the eighth mile.
So it had 2.5" pipes to each turbo and made 650whp? This GT45 makes 650-700whp on V8s' all day long. Still think 3" into it is a bad idea? I bet it would help spool to go smaller, but I think it would hurt power.
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Old 02-11-2016, 01:25 PM   #200
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Because I hate it just as much as the next guy when someone spouts out advise without data or evidence, This thread, starting at post #82 should be relevant to your interests.

$700 rear mount turbo build - Page 3 - LS1GTO.com Forums

I'd post more, but I am at work today and have limited *******-off time.

Last edited by vteckiller2000; 02-11-2016 at 01:35 PM.
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