diy "turbo no hit block" '00 BP miata - Page 6 - Miata Turbo Forum -Boost cars, acquire cats.

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Old 10-24-2014, 07:18 PM   #101
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Compression test
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Old 10-24-2014, 07:18 PM   #102
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Bad radiator cap?
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Old 10-25-2014, 02:52 AM   #103
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Quote:
Originally Posted by sixshooter View Post
Compression test
Tomorrow I will see


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Bad radiator cap?
It's a new 1.2 bar silicone cap
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Old 10-25-2014, 04:56 AM   #104
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yesterday night the exhaust gases started to smell like burning oil when in cutoff from high revs -.-'
Tomorrow I will dyno the car on 4th gear, just to be sure that the power is at a safe level
and hopefully I will do a compression test on the warm engine
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Old 10-26-2014, 02:50 PM   #105
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no compression test, I forgot that

disappointing results:



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Old 10-26-2014, 02:52 PM   #106
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Old 10-26-2014, 08:15 PM   #107
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236hp is good but the spool up seems a little slow for that size turbo.
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Old 10-27-2014, 05:44 AM   #108
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Quote:
Originally Posted by sixshooter View Post
236hp is good but the spool up seems a little slow for that size turbo.
236 hp is 183 rwhp, that's not good...
My exhaust flanges are actually 2" ID even if the exhaust ID is 60mm (close to 2.5")

Boost is at 8.7 psi, I'm thinking to raise the pressure to 10 psi, and with the allofit button 12 psi (not a big raise, but safe)

I hope to reach at least 200rwhp in this way

edit: dyno run was made with the 2.5" turbo muffler
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Old 10-27-2014, 08:51 AM   #109
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edit: dyno run was made with the 2.5" turbo muffler
I forgot about that. The small pipe and muffler explains the slow spool and stifled top end. I didn't realize they were computing engine cavallos and not wheel cavallos.
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Old 10-30-2014, 02:34 PM   #110
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News:
I will upgrade the exhaust to a 3" without cat. converter.
I'm thinking to put a magnaflow 3" muffler, like this one

MagnaFlow Polished Stainless Steel Universal Exhaust Round Oval Muffler Silencer | eBay

For the flanges I will use v-bands, precisely 2 of them: one at the end of the downpipe and the other just before the muffler.

I've only one doubt: the design of the first part of the downpipe.

this style (hammer and welding skills will help, forgot the vband, I don't have enough space to fit it):
3" Guss V-Band Hosenrohr Flansch / Kit Garrett GT25 GT2860 GT2871 GT2876 GT3071 | eBay

or this style (way more complicated):



After that I MUST have better response
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Old 10-30-2014, 02:40 PM   #111
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t25 flange

Flangia Scarico Downpipe Garrett GT25 GT28 5 bull acciaio gomito Turbo Turbina | eBay

and, if I **** off with the hammer:

Flangia Linea Scarico Downpipe Garrett GT25 GT28 5 bulloni acciaio gomito imbuto | eBay
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Old 10-30-2014, 04:18 PM   #112
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Quote:
Originally Posted by sixshooter View Post
I forgot about that. The small pipe and muffler explains the slow spool and stifled top end. I didn't realize they were computing engine cavallos and not wheel cavallos.
wohohoho!!
maybe I found the problem...
I forgot to reinstall the compressor housing o-ring

soooo...
60mm exhaust line with 2" restriction + turbo muffler + emanage blue (dunno the exact timing) + massive boost leak from compression housing + pretty hot engine = creepy spool and shitty power
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Old 10-30-2014, 08:33 PM   #113
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Old 10-31-2014, 01:12 AM   #114
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hahaha I like this guy
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Old 10-31-2014, 06:39 AM   #115
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I just find out this "ghetto street/racing" muffler

FlowTech Warlock Racing Mufflers - Free Shipping on All Orders @ JEGS
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Old 10-31-2014, 09:00 AM   #116
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Why not use a 50$ sr20 downpipe elbow? These were standard issue on no hit block kits and unlike the manifold hold together ok.

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Old 10-31-2014, 09:55 AM   #117
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^ 2" is a choke hold

that ^ ghetto muffler is what you just bought- all you need to do is cut a hole in the body adjacent to that entry pipe end. Then fab up a removable/swappable cover plate and insert for straight through flow. Do it

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Old 11-01-2014, 03:31 PM   #118
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Quote:
Originally Posted by sturovo View Post
Why not use a 50$ sr20 downpipe elbow? These were standard issue on no hit block kits and unlike the manifold hold together ok.
that's an idea... thanks!


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Originally Posted by m2cupcar View Post
^ 2" is a choke hold

that ^ ghetto muffler is what you just bought- all you need to do is cut a hole in the body adjacent to that entry pipe end. Then fab up a removable/swappable cover plate and insert for straight through flow. Do it

With an air grinder the 2" flanges can quickly become a 2.5" ID, it will be the next step before the 3" exhaust.
about the ghetto muffler: I don't wanna do that way, my ideal muffler is a straight-through, free flowing but at the same time very quiet at idle and low load conditions. The closest seems to be the dynomax vt



but I'm a little skeptical: when do I need a straight-through? when I'm not still on boost, but on WOT, expecially at low revs. On this situation the valve is still closed because there is no enough flow to open it... meh

on the other hand, this is a free-flowing muffler, but I'm scared of the cruise situation: too loud?
Dynomax 17220 Dynomax Ultra-Flo Welded Mufflers - Free Shipping on All Orders @ JEGS

Which muffler do you use?
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Old 11-01-2014, 04:25 PM   #119
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Quote:
Originally Posted by DNA54 View Post

but I'm a little skeptical: when do I need a straight-through? when I'm not still on boost, but on WOT, expecially at low revs. On this situation the valve is still closed because there is no enough flow to open it... meh
Ah, no, that's not correct. At that point you need some backpressure. You need a straight through muffler when you're flowing more air = on boost at higher RPM's.
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Old 11-01-2014, 05:16 PM   #120
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Quote:
Originally Posted by turbofan View Post
At that point you need some backpressure



I can think of no operating condition in which either a turbocharged or naturally-aspirated four-cycle gasoline engine will benefit from an increase in exhaust backpressure owing to a restrictive muffler.

This myth, so far as I am aware, was started many decades ago when it was observed that the installation of extremely oversized headers and exhaust systems caused a decrease in engine torque at low to mid RPM conditions. As exhaust pressure was observed to be lower in such designs than their predecessors, it was, at the time, concluded that this decrease in exhaust pressure was responsible for this decrease in torque.

This conclusion, however, failed to account for the fact that gas flow through the exhaust system is pulsed rather than continuous.

What happened is that by increasing exhaust diameter, exhaust gas velocity was decreased. This led to a reduction in the scavenging effect of an otherwise properly-tuned exhaust system, with a corresponding decrease in volumetric efficiency. Without the high-velocity pressure waves traveling through the system to suck the last of the fumes out of the cylinder at the top of the exhaust cycle, more exhaust gas remained in the cylinder, and cylinder fill during the intake cycle was therefore decreased.

So while it is true that an exhaust system which is optimized for maximum VE at low to mid RPM operation will exhibit higher backpressure at high RPM than one optimized for high RPM operation, this observed backpressure is a side-effect of the reduction in exhaust diameter, and an undesirable one at that. The most optimum muffler for any engine is the one which causes the least restriction to exhaust flow under all conditions while still providing an adequate level of sound reduction. The fact that, on the street, straight-through mufflers are more commonly found on turbocharged engines than naturally-aspirated or supercharged engine owes merely to the fact that, the turbocharger itself providing a high level of noise reduction, it is possible to run mufflers with little to no baffling while still achieving acceptable sound levels.
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Last edited by Joe Perez; 11-01-2014 at 06:52 PM.
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