Miata Turbo Forum - Boost cars, acquire cats.

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-   -   1984 RX-7 Race Car with BP! (almost a Miata) (https://www.miataturbo.net/build-threads-57/1984-rx-7-race-car-bp-almost-miata-62355/)

Impuls 12-17-2013 07:06 PM

So the engine is literally going to be suck/vacuum spooling the turbo? haha

bcrx7 12-17-2013 07:13 PM

Yup! It is a race car, I don't really care what happens under 4500rpm! Add ALS to that and we have a party!

18psi 12-17-2013 07:16 PM


Originally Posted by Leafy (Post 1083800)
I looked at the compressor map for this turbo. This things going to be hilarious, nothing nothing nothing, compressor surge surge, 5krpm 35psi ohmehgawd. Like literally everything under ~5k rpm is left of the surge line. This is going to be awesome.

its gonna be Ryans dyno plot x2

bcrx7 12-17-2013 07:20 PM

How many people here have run a twin scroll turbo out of curiosity and did a dyno?

bcrx7 12-19-2013 03:22 PM

2 Attachment(s)
The intake is happening!

https://www.miataturbo.net/attachmen...ine=1387484523

https://www.miataturbo.net/attachmen...ine=1387484523

concealer404 12-19-2013 03:24 PM


Originally Posted by Leafy (Post 1083800)
I looked at the compressor map for this turbo. This things going to be hilarious, nothing nothing nothing, compressor surge surge, 5krpm 35psi ohmehgawd. Like literally everything under ~5k rpm is left of the surge line. This is going to be awesome.


I know this is "wrong," but i don't give a shit. Nothing gives me the biggest boner like hearing a bit of surge on the way up.

Impuls 12-19-2013 04:26 PM


Originally Posted by concealer404 (Post 1084459)
I know this is "wrong," but i don't give a shit. Nothing gives me the biggest boner like hearing a bit of surge on the way up.

What's this "boner sound" sound like?

concealer404 12-19-2013 04:34 PM

The whole video is kinda great if you like fast street cars, but the 50 second mark is money for some major surge. Having a hard time finding a good example in-car at the moment. My car does it from time to time in cold weather under high boost, and i expect it to be a bit worse this time around. If you put in "compressor surge" on Youtube, all you get is really bad examples. You'll know if you find a car that's on the bleeding edge of it, though.


Leafy 12-19-2013 04:39 PM

You can also just look up groupe-b rally, or pretty much any wrc in the turbo age.

bcrx7 12-19-2013 04:42 PM


Originally Posted by Leafy (Post 1084485)
You can also just look up groupe-b rally, or pretty much any wrc in the turbo age.

Exactly:

concealer404 12-19-2013 04:45 PM

.... I'm not hearing surge in that video, just some compressor stall due to no BOV and some antilag.

thenuge26 12-19-2013 04:46 PM

Compressor surge happens when the compressor blade stalls.

concealer404 12-19-2013 04:49 PM


Originally Posted by thenuge26 (Post 1084490)
Compressor surge happens when the compressor blade stalls.


I guess i'm working with the definition of true compressor surge being when that happens while building boost. Not when it happens say... when you let off the throttle.

But you're right. They're both compressor stall, but one kills turbos a LOT faster, and that's the one that's being referenced when we talk about "The surge line."

thenuge26 12-19-2013 04:56 PM

No, (from what I understand at least, I did fail out of Aerospace Engineering) they are 2 different things that both happen in the situations you're referring to. Compressor stall happens when the airflow separates from the compressor blade and becomes turbulent. Compressor surge is when air goes backwards through the compressor due to the compressor not being able to flow air because of the stall.

Whether surge/stall is harder on the turbo during spool vs throttle closing, that I can't answer.

bcrx7 12-19-2013 05:08 PM

Axi-symmetric stall or compressor surge are the same thing. For a turbo charged car in racing conditions to make good power, you need to play on the edge. Again I don't see any point in this discussion, this is a dedicated race car, not a track car or daily driver. I am not going to drive around at 3000rpm saying where is my boost.

Seefo 12-19-2013 05:55 PM


Originally Posted by concealer404 (Post 1084482)
The whole video is kinda great if you like fast street cars, but the 50 second mark is money for some major surge. Having a hard time finding a good example in-car at the moment. My car does it from time to time in cold weather under high boost, and i expect it to be a bit worse this time around. If you put in "compressor surge" on Youtube, all you get is really bad examples. You'll know if you find a car that's on the bleeding edge of it, though.


what the fuck is going on with that guys car at 1:02+? I am at a loss as to what is sparking up a storm...was he using the brakes to spool?

concealer404 12-19-2013 05:58 PM

Yeah, brake boosting. Sorry to shit up the thread.

Impuls 12-19-2013 06:07 PM


Originally Posted by Track (Post 1084506)
what the fuck is going on with that guys car at 1:02+? I am at a loss as to what is sparking up a storm...was he using the brakes to spool?

Yeah 50sec+ was major brake boosting. Resulting in compressor surge from low engine RPM.
I still don't see what you're talking about how it's going going to surge at low rpm as it spools and make this "boner sound"
Unless you are just talking about surge from having a huge turbo/letting off the gas before it spools (typical 2jz sound)?

Is that what you'll be doing with this thing? :giggle:

bcrx7 12-19-2013 07:11 PM

Yup! Once I get the AWD in there haha

bcrx7 12-30-2013 12:30 AM

3 Attachment(s)
Intake piping is done! The wiring is coming along. This is going to start this week! Video coming soon!

https://www.miataturbo.net/attachmen...ine=1388381417

https://www.miataturbo.net/attachmen...ine=1388381417

https://www.miataturbo.net/attachmen...ine=1388381417


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