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PostPosted: September 20, 2008, 11:13 pm 
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I'm not sure how different the engines are, but I've seen Mazda BP-Ts from transverse applications advertised by engine importers for $1800 with the harness and ECU. It may take swapping some parts from a Miata engine to get everything to work out with swapping it into a RWD application (I'd bet mostly oil pan and pickup stuff), but it should be cheaper and more reliable than a homebrew setup.

Lower compression, forged rods, oil squirters, cast iron turbo manifold, and engine management already there and tuned by the manufacturer vs. a piecemeal build and trying to get everything to work together and not blow up seems like a no-brainer to me, but then I'm not much of an engine guy.

The 323 GT-X BP-T is rated about 180hp stock, the much rarer 323 GT-R engine is 200+, but they are all reportedly very tunable without throwing a lot of money at them.

If you go that route, let me know. I'll buy the GT-X transverse AWD trans from you. :)


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PostPosted: September 20, 2008, 11:52 pm 
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bremms wrote:
LOWER THE COMPRESSION RATIO!!! 10:1 compression is too high


Nissan ran a 9.5:1 on the RB26DETT twin turbo I6 engine straight off the factory floor stock.

So what I'd do to turbo a 4-cyl on the cheap:

Turbo: 14b w/ internal WG off a 1G DSM (90-94 Talon/Eclipse/Laser)
CBV/BOV: 1G DSM

Should be able to find those two for less than $250. I've bought complete parts cars for $500.

Manifold: I'd buy a couple flanges and weld-els and build my own: $150 max, depending on manifold design, whether you can fab your own flanges, etc. Your building/built a whole car from scratch, building a small manifold isn't much harder*

IC: Theres way too many ebay ends and cores to deal with any thing you can find in a junkyard: Most OEM units are crap (low efficiency, high pressure loss)

IC Pipes:
Cheap: Exhaust tubing
Cheaper: RV/Semi Radiator hose

Oil: I'd buy a new external cooler from Summit, etc. I'd also shoot for one thats a remote filer housing/plate too. Depending on your packaging, you might be able to feed oil to the turbo without having to buy extra hose, just fittings (T's etc)

ECU: MegaSquirt II.

Fuel: Big pump, if you used to OEM one, it'll probably work for a while, but we're talking cheap and reliable, not just cheap ;) . Walbro makes a 255lph in-line pump that you might be able to find for less than $100 if you really hunt. Easy to find at $140.

FPR: This is where I wouldn't really cheap out. Sure there are some OEM units that are vac rising rate (like the DSM one, but its got some problems). I really like the Aeromotive A1000 unit, but at $140 its not super cheap, and it only has -6AN ports. Just find one that will reference boost/vac and rise at 1:1.

That should about do it, but remember that the intake now feeds almost directly next to the wicked hot manifold and pretty hot compressor housing of the turbo so it'll need not to melt ;)


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PostPosted: September 21, 2008, 9:22 am 
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There is no substitute for cubic inches. LsX in stock form would have more power, torque, reliability and wouldn't be a whole lot heavier than the 4 cylinder with all that extra hardware. Probably cheaper too.


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PostPosted: September 21, 2008, 9:50 am 
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Why not wait another year? Are you really at the end of the work you need to do to setup, and improve your car? How about getting yourself to some road race circuits...

Your just getting started, there's plenty of fun still to be had. Doing the turbo work will keep you busy turning wrenches instead of driving. You probably don't need huge power for your first excursions to someplace like VIR or Summit Point in a new car...

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PostPosted: September 21, 2008, 10:40 am 
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4G63-7 wrote:
bremms wrote:
LOWER THE COMPRESSION RATIO!!! 10:1 compression is too high


Nissan ran a 9.5:1 on the RB26DETT twin turbo I6 engine straight off the factory floor stock.



That engine was also designed primarily for Japanese consumption where 100 octane pump gas is readily available.


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PostPosted: September 21, 2008, 11:51 am 
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Fester wrote:
4G63-7 wrote:
bremms wrote:
LOWER THE COMPRESSION RATIO!!! 10:1 compression is too high


Nissan ran a 9.5:1 on the RB26DETT twin turbo I6 engine straight off the factory floor stock.



That engine was also designed primarily for Japanese consumption where 100 octane pump gas is readily available.

You beat me to it. Octane is an unmentioned but critical component.

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Last edited by Anonymous on September 21, 2008, 1:22 pm, edited 1 time in total.

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PostPosted: September 21, 2008, 12:38 pm 
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So are you talking a cheap turbo system on a Miata engine only or were you talking about can you do it on any engine easily and cheaply?

I read it as can it be done on any engine and then the posts started lining up on the Miata engine.

The issue with the miata engine is that the factory ecu doesn't like or see boost. Many other engines ecus will recognize boost and a safe turbo is a relatively safe, easy and cheap thing to do if you stay within the parameters of the stock ecu.

So many of the 99 out of 100 KB58 quoted that blew engines were going for maximum braggin' rights. On a locost you don't want maximum braggin' rights you want good wide power band and you probably are looking at only 4-6 lbs of boost. That's a completely different beast. We don't need 12 psi of finely tuned max power. I've seen many people safely do 4-6 lbs of boost using only a Rising Rate Fuel Pressure Regulator that raises fuel pressure and therefore delivery as the boost rises.

No, that won't get you maximum power but it gets you maximum cheapness. For the longest that was THE way to turbo the Miata engine. It's not as responsive or powerful as a $4,000 set up, but with the light weight of the locost I'm not sure you'll even notice it.

If your question is specifically Miata related I'd recommend asking the same question on the Miata Powerlist. You'll find a myriad of ways to do it on the cheap and safe and you might even find some deals lurking in the background with people who have old equipment just sitting gathering dust as they finally decided they NEEDED more power.

miatapower@miatapower.net


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PostPosted: September 21, 2008, 1:30 pm 
[quote="chetcpo"]OK so I'm planning a turbo buildup for my Locost over the winter. I read lots of good info in the FAQ "turbo" thread.

Thanks for this thread. Although I only have half a cent to contribute to this question, I am interested in the discussion. I run a shop rebuilt Garrett T3 on my VW diesel. The thing cost me $900 and came with a warantee. What I think matters is the delicate balance of the two turbines and the condition of the journals. I think that we can all replace bearings. I don't think that I am equiped to do much about the turbines' balance. I have seen used turbos for as little as $300 (key words e miata VW turbo diesel) and the site has kits to rebuild one if you want. The big difference between the old turbo generation such as the Garrett T3 is "lag". Today's turbos are more expensive but the turbines are designed to work well at various rpm levels, not the case with the old Garretts.

On turbos I think the bottom line is how you use them. I have a thermocouple set in my exhaust manif so that when gas will get too hot I will know early enough to reduce the intake pressure. On this subject, the safe way is to use first a range of intake pressure comparable to that of the manufacturer. On TDI VW about 10 psi. I will run mine first to 10 psi, then 15, then 20 as the exhaust temperature will allow. I think that the greatest danger for the engine is sudden high exhaust temperature which the common coolant gauge will not detect soon enough. For conservative street driving I think that the cylinder compression ratio question should be investigated. Some of us here believe that a 9.1 -10 to one ratio is fine. They may be right. All I have read however is that bolting a turbo to a NA engine involves reducing that ratio. Who knows.

I will follow this discussion with interest as I will eventually be in the market for a turbo for my own Mazda Z5.

Philippe.


Last edited by Philippe on September 21, 2008, 7:27 pm, edited 2 times in total.

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PostPosted: September 21, 2008, 1:32 pm 
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rongaudier wrote:
There is no substitute for cubic inches. LsX in stock form would have more power, torque, reliability and wouldn't be a whole lot heavier than the 4 cylinder with all that extra hardware. Probably cheaper too.

No offense, but I'm not even going to entertain that argument right now. I'm not a big fan of hypotheticals. You build a book frame locost with the LS1 that weighs about what my car in turbo form does, with the same amount of interior space for driver and passenger, and then I'll be happy to discuss it. :wink:

And for the record I've driven and owned and worked on a LS1 equipped car so I'm not completely unfamiliar with them.

I'm not trying to be a jerk, but I don't want my turbo thread to degrade into one of these threads.

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PostPosted: September 21, 2008, 1:55 pm 
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Location: Ithaca and Watkins Glen, NY
The BP motor is great for turboing, it even has oil squirters built in to the pistons. I am finishing my BP powered festiva right now with a turbo kit built mainly from ebay parts, so far so good, but I am also using a Megasquirt setup for tuning, and Zeitronix for wideband A/F, EGt temps, and Boost gauge.

The engine can handle up to 21 psi but it won't last long, that is also on race gas running a t3/t4 turbo with a .57 trim. I have seen one producing 304 horsepower, but again reliablity goes out the window, and since my car is not a daily driver its fun to make go boom on stock internals.

Once I finish this I will run a similar setup in my locost, if I ever get to building it :-) Good luck Chet.

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PostPosted: September 21, 2008, 3:19 pm 
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chetcpo wrote:
rongaudier wrote:
There is no substitute for cubic inches. LsX in stock form would have more power, torque, reliability and wouldn't be a whole lot heavier than the 4 cylinder with all that extra hardware. Probably cheaper too.

No offense, but I'm not even going to entertain that argument right now. I'm not a big fan of hypotheticals. You build a book frame locost with the LS1 that weighs about what my car in turbo form does, with the same amount of interior space for driver and passenger, and then I'll be happy to discuss it. :wink:

And for the record I've driven and owned and worked on a LS1 equipped car so I'm not completely unfamiliar with them.

I'm not trying to be a jerk, but I don't want my turbo thread to degrade into one of these threads.


Okay I won't try to hijack your turbo thread. You know I won't be able to put an LsX into a book frame and still have the same interior space. In fact, I'm beginning to doubt it's going to be practical to even try. I will say, i'd like to get as close as possible to the book frame, and I'll bet the weight will be within 100-200 pounds. We'll see, I haven't cut my first tube yet. :wink: BTW, I think I'll borrow that trick sidebar idea you have.


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PostPosted: September 21, 2008, 3:44 pm 
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Gforce, you've got mail.

I don't know if you can handle an lsx locost Rongaudier. I'd hate to see you loose your medical. How about the GM iron duke? :P

Except for the newest stuff, turbos don't have bearings, they have bushings. The shaft floats on a film of oil. The turbine wheel/shaft and the impeller are not keyed to each other so the parts are not indexed/balanced. The shaft is threaded opposite the direction of rotation so they don't back off. The nut torque is very low, maybe 10 ft/lbs. Overhaul kits are $100-150 depending on the turbo.

I bought a Greddy kit for the 1.6 miata for $700 in the 90's and installed it on my wife's '93 miata with 105,000 miles. Much of the greddy components are junk.

Initially, my initial timing had to be moved back to 6 degrees, which made the car a slug taking off before the revs came up. I added the MSD boost retard made for the supercharger applications, which allowed me to bring the initial up around 10 degrees.


I used 18 wheeler turbo clamps and hoses. The clamps were spring loaded T-bolts, which expand and contract with the pipes while maintaining tension. Worm screw clamps don't. T-bolts have a narrow range of adjustment so one must know the diameter required.


I had to add a oil cooler to get dino oil to last more than 3,000 miles before breaking down and loosing pressure. No coking problems in 250,000 miles with dino and idling for a minute before shutdown. I never touched the wastegate or the rising rate fuel pressure regulator. I replaced everything else atleast once, with a better part.

With a wideband o2 you know the a/f ratio. With egt, you just know it is getting hotter as you lean it out. Lean of peak looks the same as rich of peak.


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PostPosted: September 21, 2008, 5:12 pm 
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Fester wrote:
4G63-7 wrote:
bremms wrote:
LOWER THE COMPRESSION RATIO!!! 10:1 compression is too high


Nissan ran a 9.5:1 on the RB26DETT twin turbo I6 engine straight off the factory floor stock.



That engine was also designed primarily for Japanese consumption where 100 octane pump gas is readily available.


Japanese pump gas is 100 RON.
If you live outside of California, you can get 93 AKI (RON+MON)/2

100 RON = 95 AKI

The Skyline GT-R was also sold in the UK and Australia. The engine was identical to the RB26 for the Japanese market. The top fuel in the UK is 98 RON.
98 RON = 93.1 AKI

Moral of the story, the RB26DETT was designed to run 9.5:1 compression on 93 octane as Americans measure it.


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PostPosted: September 21, 2008, 5:59 pm 
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Quote:
I don't know if you can handle an lsx locost Rongaudier. I'd hate to see you loose your medical. How about the GM iron duke?


Hey if I can handle 40000 HP of Pratt and Whitney JT8-219 I can for sure handle a measly 500 HP in a locost! :twisted:


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PostPosted: September 21, 2008, 7:26 pm 
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I think I made the decision to go with a Turbo Metro 1.0L & a 6spd - LOTS of turbo info on Swift.net except they're a bunch of punks. Need to be able to wade through all the BS flames. I'd like my Locost to be an exercize in economy & MegaSquirt programming. + the engines are dirt cheap to replace if you grenade. Not likely as it seems tough and I don't want to push the limit's much. Everyone wants a bigger turbo, I'll take theirs. I have a stock 3cyl turbo Sprint engine/trans in my classic Mini so I want to learn one engine only. Will be following this thread VERY closely. PS - I drove VW vans for years so the lack of power argument doesn't fly. Very Chapmanesque if you ask me. The original Locost was a One Liter - 96 Miata donor for sale I think.


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