more boost with restricted exhaust?
Thread Starter
Joined: Nov 2001
Posts: 7,903
Likes: 1
From: Cleveland, OH
more boost with restricted exhaust? Before I had the 3.5" downpipe on my OFI kit actually mated to my 3" magnaflow catback, it seemed most boost it would make is 13.8 psi (dunno what spring is in the gate) on just spring pressure. Now that the pipe is all mated, my boost on spring goes to 17.8....4psi difference. Does the backpressure hold the tial 44mm wg closed more and allow the boost to go up? It felt more powerful or at least the same power at 13.8 vs 17.8 psi...i attribute that to the lowered exhaust flow i now have. I am getting a cutout friday but just wondered in the mean time if this is a common occurence.
Oh, torco does work.....i got some kr after 16psi but torco totally eliminated it....this was today...same tank of gas...IAT everything...got knock...added torco...drove for 5 minutes to let it mix and then no more knock.
Oh, torco does work.....i got some kr after 16psi but torco totally eliminated it....this was today...same tank of gas...IAT everything...got knock...added torco...drove for 5 minutes to let it mix and then no more knock.
Yes they are. Also for the mid-frame turbos such as yours, they are being labeled T5 blankets. Weird, but only way to seperate all these frame sizes.
The links are now up....
http://www.forcedinductions.com/product7.htm
The links are now up....
http://www.forcedinductions.com/product7.htm
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Thread Starter
Joined: Nov 2001
Posts: 7,903
Likes: 1
From: Cleveland, OH
i dont think it will fit either? As soon as DRTurbo said it was in stock, i ran outside to look and it looks too close. Prolly just get the housing coated and let it rip
Tom, let us know what the boost reaction is at wot with/without cutout.
I am getting one friday and will do the same....hope to hit the track sunday...
Tom, let us know what the boost reaction is at wot with/without cutout.
I am getting one friday and will do the same....hope to hit the track sunday...
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if the w/g is routed into the dp you can see an increase in boost w/ restriction or no boost change at all.. what is more typical is that when the w/g is vented outside (dumped) you can see a loss of boost w/ restrictive cat back.
Thread Starter
Joined: Nov 2001
Posts: 7,903
Likes: 1
From: Cleveland, OH
David, mine is routed into the dp....and i see an increase in boost. After i get the cutout, I bet it will haul *** at 18psi....as you already know with your setup 
Just tried it out. Two 2.75 pipes to a sincle 3.50 pipe to a 3.50 cutout to a 3.00 pipe that runs to a Borla with one side completely open.
Cutout closed = 11.5psi
Cutout open = 12.0 psi
based on EB2 memory
Higher boost may make a bigger difference.
Cutout closed = 11.5psi
Cutout open = 12.0 psi
based on EB2 memory
Higher boost may make a bigger difference.
i hate to hijack your thread, but i'm about to run into the same delima i think. i've got a 3.5" DP and 3.5" all the way out the back w/ a spintech muffler. i've decided to put a magnaflow 3.5" flow through muffler in it's place running straight out the back. do you guys think it'll increase boost by switching to a non-chambered exhaust or decrease it?
TECH Addict
Joined: Jul 2005
Posts: 2,153
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Be careful. I severely blew both head gasket, to the point of hydrolock, doing what you're about to do.
I had my car set up running about 20 psi using a 3.5" Aerochamber muffler. I made no other changes except replacing the muffler with a 3.5" Magnaflow with the same external dimensions. I have no idea where the boost went, but it was high enough to do said damage. That's when I found that the minimum boost was now 17 psi instead of 11 on just the WG spring.
Mike
I had my car set up running about 20 psi using a 3.5" Aerochamber muffler. I made no other changes except replacing the muffler with a 3.5" Magnaflow with the same external dimensions. I have no idea where the boost went, but it was high enough to do said damage. That's when I found that the minimum boost was now 17 psi instead of 11 on just the WG spring.
Mike
Originally Posted by engineermike
Be careful. I severely blew both head gasket, to the point of hydrolock, doing what you're about to do.
I had my car set up running about 20 psi using a 3.5" Aerochamber muffler. I made no other changes except replacing the muffler with a 3.5" Magnaflow with the same external dimensions. I have no idea where the boost went, but it was high enough to do said damage. That's when I found that the minimum boost was now 17 psi instead of 11 on just the WG spring.
Mike
I had my car set up running about 20 psi using a 3.5" Aerochamber muffler. I made no other changes except replacing the muffler with a 3.5" Magnaflow with the same external dimensions. I have no idea where the boost went, but it was high enough to do said damage. That's when I found that the minimum boost was now 17 psi instead of 11 on just the WG spring.
Mike
TECH Addict
Joined: Jul 2005
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Turbo383Ws6, our combo's are very similar. I have the T76GTS on a 388 LTx. What mph are you running at the track? Dyno numbers? I've been thinking about going with a 3.5" downpipe instead of my 3", but can't decide if it's worth it.
Mike
Mike
Seems like if you have restrictive exhaust, the boost at the turbo will be high but not after it.
I'm running a 4" DP and a 4" exhaust with a bullet dumped at the rear axle, no real restriction there.
I'm running a 4" DP and a 4" exhaust with a bullet dumped at the rear axle, no real restriction there.
Thread Starter
Joined: Nov 2001
Posts: 7,903
Likes: 1
From: Cleveland, OH
my wg is referenced from the turbo....i followed the eboost instructions and did it the way they said..my boost gauge is referenced from the intake. Ill have a cutout tomorrow and can say definitively what MINE does
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Joined: Jul 2005
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Originally Posted by cablebandit
my wg is referenced from the turbo....i followed the eboost instructions and did it the way they said..my boost gauge is referenced from the intake. Ill have a cutout tomorrow and can say definitively what MINE does