DIY Turbo Discussion greddy on a 1.8? homebrew kit?

Smallest Turbines?

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Old 10-31-2006, 02:23 PM
  #21  
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Originally Posted by JonC
The k03 falls flat on its face around 200hp (~12psi in a 1.8l Jetta/Audi).
On the 2.0T FSI engines, they're topping out around 220-230whp at ~20psi of boost.

In the grand scheme of things it is a small turbo. Its more just an exercise in fun for me, as my Miata is no-longer my daily driver and I've wanted to do this for years.... just never really had the time to get around to it.
I'm not trying to dissuade you.

So maybe it doesnt spool til 2600 or so, ok. There are plenty of Miatas running around that are just thinking of coming out of vaccuum at 2600rpm. If I wanted instant boost I'd get a Coldside PD blower.... Instead I want something that is neat and different (I'd be what, number three?) and that has turbo whine like no other. Which K03's whine pretty loud... especially with only an aircleaner on them.
I'm not trying to dissuade you.

How will it spool? IIRC the compressor maps for a stock k03 show two of them coming into boost around 2300-2500rpm. I'll have to check when I get home, but it wasnt any number that was absurd like some of the really large turbo miatas that don't come into boost til around 4000rpm.

How will it actually spool? Noone has done it yet, so that is yet to be seen.
So what're you waiting for!?

I was always told if you are below 3krpm in a Miata except when stopping you are driving it wrong
And I've always told those people you must not live in the real world with stoplights and traffic...or you only drive your Miata on weekends, on the highway or on the track. Mine's a daily driver, and I like having some boost below 3000 RPM. It's not every day I get to wind it out to redline.

And I'm talking a parallel setup, not sequential.
I know. I tried to point that out to Jay, and it looks like Arkmage still doesn't get it:gay:
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Old 10-31-2006, 03:24 PM
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Originally Posted by bripab007
On the 2.0T FSI engines, they're topping out around 220-230whp at ~20psi of boost.
The 2.0T runs a different K03 than the ones I'm getting from what I can gather. Noone has said for sure, but the general impression I have found from reading everything people have said is that it is a K03 Sport or a K03/K04 Hybrid.

Mine are the Pre-'02 K03's which are the smaller ones... but again, we shall see.

I'll map it out while I'm at work and see how the numbers work out.
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Old 10-31-2006, 03:26 PM
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Aha...see there, I knew those K03s were different, but was not aware they were markedly so.

I'm sure you can get those K03s a heckuva lot cheaper and easier than those small Garretts, too, huh?
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Old 10-31-2006, 03:41 PM
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I'll bet the VAG 1.8 head flows a lot better than the Miata head to spool the K03. My opinion, two turbos, a custum funky manifold, lots more piping = more stuff to go wrong. It certainly isn't a budget solution. Would be cool though.

I certainly hope anyone going the TT route has good welding skills or a good friend who does as the manifold itself will be pricey.

Frank
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Old 10-31-2006, 04:21 PM
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Originally Posted by bripab007
I'm sure you can get those K03s a heckuva lot cheaper and easier than those small Garretts, too, huh?
I'll let you know tommorow. But it looks that way. Many VW guys dump their stock K03's for larger turbos, so they are a dime a dozen. I've seen them go for as low as $30 a pop for one in decent shape that needs new bearings, and about $200 for one that has minumal shaft play and is really good shape.

Plus they have round turbine inlets and outlets, so making a flange is not complicated at all, as there is no custom shaping of tubing to make it fit. Add in the fact that it is a water and oil cooled turbo.. more piping, but hopefully longer life. About the only downside is that it is a journal bearing.

Originally Posted by fmowry
I certainly hope anyone going the TT route has good welding skills or a good friend who does as the manifold itself will be pricey.
I have access to a TIG the size of a VW Bug. So that is not an issue. I also have a drill press, arbor press, bandsaw, etc. Oh, and a plasma cutter. Sound be fun.
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Old 10-31-2006, 04:35 PM
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The original poster was talking about sequential. What the hell are you guys going on about?

I own a 99 base and Im thinking of going turbo... but not just turbo... SEQUENTIAL Turbo...
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Old 10-31-2006, 05:02 PM
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Originally Posted by jayc72
The original poster was talking about sequential. What the hell are you guys going on about?
We are a bit more realistic in our desires

Sequentials require all sorts of mechanicals to make them work well. You have to have an exhaust diverter so that you can spool the small turbo up quickly, then you have to have some sort of pre-spool control to get the large turbo to start spooling. You also have to be able to keep the air from the small turbo from flowing into the larger turbo and pushing it backwards or just plain flowing out. The list keeps going. It is doable, but takes a lot of work.
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Old 10-31-2006, 06:26 PM
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Originally Posted by JonC
The k03 falls flat on its face around 200hp (~12psi in a 1.8l Jetta/Audi). In the grand scheme of things it is a small turbo. Its more just an exercise in fun for me, as my Miata is no-longer my daily driver and I've wanted to do this for years.... just never really had the time to get around to it.

So maybe it doesnt spool til 2600 or so, ok. There are plenty of Miatas running around that are just thinking of coming out of vaccuum at 2600rpm. If I wanted instant boost I'd get a Coldside PD blower.... Instead I want something that is neat and different (I'd be what, number three?) and that has turbo whine like no other. Which K03's whine pretty loud... especially with only an aircleaner on them.

How will it spool? IIRC the compressor maps for a stock k03 show two of them coming into boost around 2300-2500rpm. I'll have to check when I get home, but it wasnt any number that was absurd like some of the really large turbo miatas that don't come into boost til around 4000rpm.

How will it actually spool? Noone has done it yet, so that is yet to be seen.

I was always told if you are below 3krpm in a Miata except when stopping you are driving it wrong

And I'm talking a parallel setup, not sequential.

Honestly I dont like boost too soon on the miata. If I was making 10psi @ 3000rpm I would be blowing my tyres off . I get 7psi by 3400rpm and 10psi by 3700rpm on my car and it still spins 1st and 2nd ( with 225 wide hancook rs2's in the rear ). I would expect the K03's to hit full boost around 3500rpm in the miata...maybe sooner since they have a very small light turbine in them. My friends Jetta could make 15psi @ 2100rpm with a 3" exhaust so I know they will spool sooner than 4000rpm.
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Old 10-31-2006, 06:28 PM
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Originally Posted by fmowry
I'll bet the VAG 1.8 head flows a lot better than the Miata head to spool the K03. My opinion, two turbos, a custum funky manifold, lots more piping = more stuff to go wrong. It certainly isn't a budget solution. Would be cool though.

I certainly hope anyone going the TT route has good welding skills or a good friend who does as the manifold itself will be pricey.

Frank
Yeah, but then the VW has a crappy exhaust manifold and restrictive downpipe and its still making full boost around 2000rpm.
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Old 10-31-2006, 08:01 PM
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DAmn guys!! FREE FOR ALL???
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Old 10-31-2006, 10:19 PM
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Originally Posted by reliabilitygator
DAmn guys!! FREE FOR ALL???
Not really, we just jumped from sequential to parallel. Same arena, much easier to do. If you really want to do your sequential setup, go for it. I'd love to see one, but go find someone with a RX7-TT with the sequential setup and look at how many vaccuum lines (I think it is like 27-37) it takes to get it to work, then look at how many actuators have to function for it to work. It is not easy to do, nor is it easy to keep working.

A turbo-compounding setup might be easier to do.... just a thought though.
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Old 10-31-2006, 10:30 PM
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Originally Posted by AndyFloyd
Yeah, but then the VW has a crappy exhaust manifold and restrictive downpipe and its still making full boost around 2000rpm.
Very true. When I put the numbers on the compressor map tonight for a 1.8 with one k03 it is kinda scary, anywhere beyond about 3.5k you are down around 50% efficency. Granted 3k rpm is right around 68%-73% depending on the boost, which is right around cruise RPM, so that works. You just reach the choke point (12-14psi) pretty quick if you start upping the boost and run to redline. Kinda explains the lacking top-end in my VW.

And for those that want to know... by the chart, two k03 turbos on a 1.8 miata should have boost onset around 2200-2400rpm, and you can run up to around 20-22psi before choke point (at higher than 2400rpm, obviously). At 4000rpm anything from 8psi - 18psi is right in the most efficent part of the map (73%), and 20psi is only down to 71%.

This of course is assuming no pressure drop, standard day, sea level, etc, etc. Which we all know is bullshit. So take it as you will. I'll post the graph when I dig my laptop out.
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Old 11-01-2006, 06:25 AM
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Originally Posted by reliabilitygator
DAmn guys!! FREE FOR ALL???
You'll run into many of the same issues be it sequential or parallel so the info is still pertinent.

Frank
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Old 11-01-2006, 02:08 PM
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As before, standard day, no pressure drop, ideal manifold, etc. It wont perform this well in the car. This is for two k03 turbos, not one. The colored lines are RPM, the points on the lines are 6,8,10,12,14,16,18,20psi of boost.

Enjoy, and please if you see an error point it out.
Attached Thumbnails Smallest Turbines?-turbochart.jpg  
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