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Old 08-17-2016, 12:11 AM   #1
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Default Is my exhaust a major bottleneck?

I'm running a stock 1.6, greddy turbo/manifold, 2.5" downpipe, and a 2.5" crush bent exhaust straight pipe all the way back. I figure the effective diameter of the crushes are in the realm of 2-2 1/4". I'm currently running 17psi spraying 100% meth with a 575mL/hr nozzle and @ 20* of timing up top. According to v dyno I'm at about 260whp. Take that as it is and it may not be accurate, but from what I can compare it to it's at least somewhat close. I'm wondering if I will see any noticeable gains from putting on a 2.5" mandrel bent exhaust, whether it be spool or power. I currently see 17psi by 4400rpm or so but I've also kept timing fairly conservative to keep torque down to save the 5 speed and my rods. Any input is appreciated.
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Old 08-17-2016, 12:16 AM   #2
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3" or go home. and yes you should pick up power and torque and spool
I seriously doubt you're making that power figure on your setup, but you already mentioned that.
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Old 08-17-2016, 12:21 AM   #3
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Sweet. 3" it is then. I've tried adding more timing after meth and I didn't gain any power up top. I'll be adding boost once the 6 speed is in next weekend. I'm hoping to break 300 with the stock block and this turbo. From what I can see on the compressor map it started dropping efficiency once I go past 18psi or so. I'll see what this baby turbo can do though. Any suggestions to squeeze more out of my shitty motor?
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Old 08-17-2016, 12:24 AM   #4
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basically let it breathe
make sure intake/fmic/piping doesn't have bottlenecks either, the greddy did come with that terrible elbow.

throw it on the dyno afterwards, I'm guessing 250-270 all said and done, and 240ish currently
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Old 08-17-2016, 12:26 AM   #5
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Intake piping is larger than turbo inlet, IC piping is custom 2.5" with a mishimoto z-line. Could be some gains to be had there if I remove some of the 90s and such. But that's more work than I want to do before the 1.8 is in. Don't think 300 is possible with this turbo?
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Old 08-17-2016, 12:30 AM   #6
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I dunno if I'd say impossible, but I'd be extremely impressed to see it.

Back in the day we had guys with "optimized" greddy setups and all seemed to be around 250 full tilt, don't remember if they were spraying down the house with meth though.

Give it a shot. The funnest times I've had was tuning cars where no one cared about the engine and we tried different things...."for science"
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Old 08-17-2016, 12:33 AM   #7
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I agree 100% with that. I'm one to love testing my limits. And testing them as a tuner sounds really fun. Hopefully when the exhaust goes on I can make more with timing. If it blows up that's more incentive to begin my 1.8 build is all. Does anyone sell 3" exhausts that aren't overpriced as hell? Or should I have the local shop crush bend a 3.5" to make due?
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Old 08-17-2016, 12:43 PM   #8
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flyin sells 3" exhausts for ~$750, but that is probably 'overpriced as hell'.
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Old 08-17-2016, 12:52 PM   #9
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enthuza has a budget option that's cheap. 450?
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Old 08-17-2016, 01:54 PM   #10
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Enthuzas are great. Highly recommend them.
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Old 08-17-2016, 04:40 PM   #11
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You could always pull the rear section of the exhaust off to see what virtual dyno says with an open downpipe. Maybe it's just because I'm poor, but for me it'd be worth seeing what difference it makes before spending money on a bigger exhaust. I would think a straight through 3" shouldn't really lose anything over an open downpipe on your setup.
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Old 08-18-2016, 12:44 AM   #12
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I plan on testing with open downpipe. Yes 750 is "overpriced as ****" everything from ******' Miata is. Aside from a few things like their clutches.
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Old 08-18-2016, 11:10 AM   #13
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$750 isn't over priced as ****. Go price out the cost of stainless steel for materials. Then factor in the cost of labor to build and exhaust. Yes they have it all jigged out, and make some money off them, but they definitely are not over priced.
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Old 08-18-2016, 11:14 AM   #14
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But bro, he can pay like 100 less for a birdpoo welded mismatched crushbent pile of garbage from the local place?
lol

But yeah, 750 for a full exhaust with quality materials and perfect fitment is by no means overpriced.
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Old 08-18-2016, 11:30 AM   #15
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I just looked and the FM one includes a CAT in it also. So it is priced about $50 more then Enuthza, so honestly not badly priced at all.
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Old 08-19-2016, 05:19 PM   #16
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I find it hilarious how big of a circle jerk there is for FM. Literally everything on their website can be found cheaper elsewhere. It may be quality stuff, but it's overpriced.
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Old 08-19-2016, 06:17 PM   #17
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Quote:
Originally Posted by Rshannon81 View Post
I find it hilarious how big of a circle jerk there is for FM. Literally everything on their website can be found cheaper elsewhere. It may be quality stuff, but it's overpriced.
I'm not circle jerking anyone all I am talking about is their exhaust. I build exhausts. I know what material prices are. I know what labor prices are. They are not over priced for what you get. Enthuza is the next well known quality exhaust maker and he is only $50 cheaper then FM for the same stuff.
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Old 08-19-2016, 08:13 PM   #18
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I got my exhaust from the fence supply store, and mandrel pipe from Columbia river. Gained tons of spool. Like $48 total.
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