Miata Turbo Forum - Boost cars, acquire cats.

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-   DIY Turbo Discussion (https://www.miataturbo.net/diy-turbo-discussion-14/)
-   -   Rear mounted turbo? (https://www.miataturbo.net/diy-turbo-discussion-14/rear-mounted-turbo-20249/)

spike 04-29-2008 12:32 PM


Originally Posted by Braineack (Post 249255)
http://i156.photobucket.com/albums/t...awes/turbo.jpg






Enough said. That toy of a turbo should spool fully during cranking. IIRC, it's a Garrett T2 compressor wheel and a T15 Turbine at .48 A/R.

What a complete piece of crap! can it get anymore ghetto looking?

Will it even hold up to a 2 mile test drive without falling apart.

Zabac 04-29-2008 01:54 PM

that piece of turd may hold up, but why in the fuck is that thing in the trunk?
Isn't the whole point of rear mount to save space, and you got plenty under the trunk...

y8s 04-29-2008 02:05 PM

breathing in your exhaust leaks sure does cause you to make bad decisions.

18psi 04-29-2008 02:44 PM


Originally Posted by y8s (Post 249430)
breathing in your exhaust leaks sure does cause you to make bad decisions.

so true.....and think of the heat that thing will be generating into your trunk not to mention the gas tank is not too far away.....overall a retarded idea

Braineack 04-29-2008 02:48 PM

no airflow = great heat = more iefficiency :jerkit:

The_Pipefather 04-29-2008 02:58 PM

i dont know about rear mounts, but subaru mounts their turbos at least 30" from the cylinder head, and so does porsche to a lesser extent.

http://www.agency-power.com/catalog/...apheader4a.jpg

Granted this is because of the packaging disadvantage these cars have, but what if the turbo is mounted just before the stock cat location in the miata? I'm sure a tiny KKK off a VW 1.8T or similar would fit there, and spool pretty well too. This would bring down the cost of the whole system, for example the manifold and downpipe wouldn't be needed. Of course, you'd still have to deal with problems like oil scavenging. The oil inlet and water lines wouldn't be an issue other than being freakishly longer than normal.

Braineack 04-29-2008 03:05 PM

but at the same time, there's plenty of room next to the engine, without the need of pumps and bracketry and this and that.

The_Pipefather 04-29-2008 03:07 PM

Definitely, but I'm just thinking about the cost aspect of it. That's nearly $500 saved in parts alone for someone who's on a really tight budget. I'd have done it if I hadn't been this deep into my build. Even at the risk of getting ridiculed and laughed at.

Zabac 04-29-2008 03:13 PM

I'f I had to rig it that bad, I'd rather not Turbo at all.

Bond 04-29-2008 10:49 PM

wow... that is hideous. Its not the greatest layout for a miata.

240_to_miata 04-29-2008 11:40 PM

haha i like that lsx comment. Ive sat in some of my classes daydreaming about just building an insane LSx miata with twin turboes mounted in the rear. I mean why not? ...




dont answer that

cjernigan 04-30-2008 12:02 AM

The only good part about that rear mount in the trunk is you can fab a grill screen and to while tailgaiting after a good boosted run.

Would be pretty nice to have some steaks ready after a good mountain run.

SolarYellow510 04-30-2008 12:04 AM


Originally Posted by The_Pipefather (Post 249477)
i dont know about rear mounts, but subaru mounts their turbos at least 30" from the cylinder head, and so does porsche to a lesser extent.

http://www.agency-power.com/catalog/...apheader4a.jpg

Umm, this is a 996-up turbo header. Really doesn't get better than that (the basics of 3 short runners, not the specifics of this design):

http://www.vividracing.com/catalog/w...wastegate7.jpg


I'm sure a tiny KKK off a VW 1.8T or similar would fit there, and spool pretty well too.
I've thought about the K03, because people take them off all the time. It spools off idle, but it runs out of flow and torque drops off rapidly after about 4800 rpm on a 1.8L. Even on a 1.6L, it would be small.

I think a WRX turbo would be a better choice, as it's nice and small and is frequently upgraded.

magnamx-5 04-30-2008 12:04 AM

:lol: man are you serius? I will give you props for asking intelegnetly but as my buds have said and shown a rearmount turbo is one of those if you can and wan to then do type things. There is so much room in our engine bays it isn't even funny man, turbos do not take up alot of room. And ceramic caoting is a great way to keep temps down. GL I hope you survive the initial hazzing cause you actualy seem intelegent. :bigtu: Just not knowledgable.

disturbedfan121 04-30-2008 12:08 AM


Originally Posted by The_Pipefather (Post 249477)
i dont know about rear mounts, but subaru mounts their turbos at least 30" from the cylinder head, and so does porsche to a lesser extent.

well that mainly becuase they you an "H" block instead of the traditional inline 4, hell turbo subarus still have "headers" along with the turbo

The_Pipefather 04-30-2008 01:16 AM


Originally Posted by SolarYellow510 (Post 249755)
I've thought about the K03, because people take them off all the time. It spools off idle, but it runs out of flow and torque drops off rapidly after about 4800 rpm on a 1.8L. Even on a 1.6L, it would be small.

Mounting a turbo 10" from the head, and mounting it 30" from the head has different demands made on the turbine. In the latter case, significant amount of heat would have been lost from the gas by the time it reaches the turbine, hence a smaller turbine would be required to achieve the same response. That's why I said K03, not the TD04 which is big enough to be mounted in the regular position.

18psi 04-30-2008 02:04 AM

the turbo being mounted where it is on a subaru doesnt have much to do with anything more than space...the place it sits pretty much is THE ONLY place you can mount it, and THE CLOSEST that they could get that sucker to the actual exhaust ports in heads.

take a look at my engine bay during turbo swap:
http://i54.photobucket.com/albums/g9...Picture020.jpg
there is BARELY any room in there as is


now dont quote me on this, but i think the long header piping actually has something to do with subaru's generally having more torque than say evo's, while the evo's turbo sits mere inches away from teh engine, it holds boost all the way up top and usually has a little bit less torque and more peak power. on a subaru, even with a large turbo, the power usually peaks a bit before the redline and usually boost starts to taper, even using a large turbo and a mbc, it still tapers up top. so they usually have a SHITLOAD of torque come on in the midrange, and then start to die off towards the top....im assuming a rear mounted turbo kit would have more lag than normal, then have a ton of torque, and start to taper off up top pretty steep....which is kinda dumb: no lowend, no topend, just a mild push of torque exactly in the middle where its not here nor there....

feel free to correct me if im wrong.....i am merely speculating

J.T. 04-30-2008 02:09 AM


Originally Posted by 18psi (Post 249798)
the turbo being mounted where it is on a subaru doesnt have much to do with anything more than space...the place it sits pretty much is THE ONLY place you can mount it, and THE CLOSEST that they could get that sucker to the actual exhaust ports in heads.

take a look at my engine bay during turbo swap:
http://i54.photobucket.com/albums/g9...Picture020.jpg
there is BARELY any room in there as is

Truth, where else do you want them to put it? Only way to place it closer to the exhaust ports would limit you to putting it in the crankcase or the oil pan

18psi 04-30-2008 02:11 AM

well they COULD raise the engine a bit and fit some small ass turbo in there, but that would be dumb as hell, not to mention kill the cars cornering/performance

J.T. 04-30-2008 02:15 AM

Then they'd also have to run a lot more intake piping


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