Turbocharged Locost
 

And so it begins.

Being tired of complaining about terminal speeds on longer straights I found used Garrett GT28R or new name GT2554R ball bearing turbo to help the car. The goal is to have reliable 200-240 rwhp with instant spool and still good at track and autocrosses. Wastegate will be separate 35 mm Tial. Fuel will be fed through 460 cc/min RX-7 injectors driven by Greddy Emanage Ultimate. Intercooler is still open, possibly RX-7 Gen II. intercooler pipes 2" to keep volume and response better.
Head could be 99 which has better flow than previous 96.
Exhaust needs to be remade. Log manifold made out of weld-els and rest of the exhaust should be made from mandrel bent 3" tube.

Critics, comments and suggestions welcome.

hrk

http://russmarshall.com/v/cars/cmc7/power/turbo/

wow.

First off, great pics, I love the step by step. Hope to do it myself someday.

Seems odd that you'd be this far without an IC.

Where do you live, I want a ride. Or atleast a viewing session so I can gawk.
Less than 1200lbs?

Too fancy for your power goals. Ditch the following for savings:
-GT series turbo
-external WG
-99 head

You will be fine with an internally gated T3 60 trim at those power levels. As long as the exhaust is free flowing, there shouldnt be any lag.

hrk- I have a 99 head and manifold, I'm in Decatur. Don't you have a 1.6 rear in there? - rob

The GT2554R is the turbo you want for this application.

Mark

Thank you for all comments! I do appreciate them.

I have few intercoolers which I'll try to fit into nosecone.
Weight 1420 wet with all safety equipment and 10 gallon fuel cell half full.

I want to overbuild the engine so I can run with minimal boost and thus less heat generation. The car is used in road racing typically for 30 minutes at a time with 75-80% of that time in full throttle. Less pressure and heat means I should be able to finish more often.

I already have 99 head and intake from used motor, thank you.
As well as wastegate.

Thanks for all comments, I am still looking for BOV, vents to atmosphere since I am using MAP already.

Also I have Individual Throttle bodies, but there seems to be varying opinions of usefulness of them in charged motors.

hrk

I think that is way too restrictive a turbine for road racing. Youll get quicker spool, but it will trap a lot of heat in the head.

I honestly dont think your car is going to be falling out of boost with even a far larger turbo. Driving my car under track conditions with my much larger turbine and much less efficient compressor, I am still never out of boost. And I find the T3/T04B too small for street use. Above 120mph the EGTs get too high for my happiness so I'm going for a bigger turbine. Less restriction for the win.

I have no idea what your talking about beerslurpy

You dont know what a turbine is or you disagree with me? Make a substantive response.

Well when the HP level is only 200-220 RWHP you should be able to control the EGT's fairly easily. This is not to say that a larger turbo won't work better, but for Auto-x spool can be a critical factor... On a real track, yes, a larger turbo might be the better choice, however the Locost is a lighter car and will likely generate less load (and heat) than the Miata application.

I just hope I didn't go too big with my Turbine.

Mark

Ill make whatever fucking response I want. My post was exactly what I wanted it to say, some of your comments didnt make damn sense.

You can answer however you want, but youre coming across as a kind of infantile. Or maybe stupid. Your posts are too vague for me to figure out what kind of asshole you are.

If you disagree, say why.
If you dont understand, ask questions.

You have no idea how infantile I am. Stupid, probably but not about turbos. As for you figuring what kind of asshole I am, Not really my concern but from your posts im gonna guess your not the sharpest tool in the shed so Ill forgive you for not knowing.

Fortunately, there is no reason for me to ask questions or state why I disagree.

Except it makes you look like a postwhore who doesnt know anything and is just being contrary for some fickle personal reason.

You've had a turbo on your car for all of a day and 2 psi of boost? You are not quite an expert yet grasshopper.

I put together my own kit and have been running 15+ psi for almost 4 years now. I have done loads of datalogging with different parts and spent years of time staring at the various gauges* as I drive around. I broken stuff and I've found out the limitations of lots of parts- and I've discussed my findings with other miata (and other car) turbo owners for years. Which is where my experience and knoweldge comes from.

I'm not as knowledgable as markp or the other guys who do this sort of thing for a living every day of the week, but I know a hell of a lot more than the average person who is just starting out.

*boost, oil pressure, temp, egt, wb

Cat fiiiiiiiggggggghhhhhttttt!!!!!:eek5:

Rip her shirt offffffffffffff!!!!!!

:drama::yippee::drama:

haha ya got me, im a postwhore... pretty harsh.

Not really sure why you brought up breaking things, but congratulations (i guess).

Im glad you know more than the average person, not sure why that matters either.

I like learning about you tell me more.

http://www.thestudentroom.co.uk/imag...rry_smilie.gif

Thanks for comments and amusement too :)

While I share the concern of having too small turbo, especially turbine side, I'll try to make it's life a bit easier by increasing volumetric efficiency of the motor so I don't have to run high pressures.
I agree with Markp that instant spool is required in autocross. In open track it can be driven around very easily, but not in autocross.
Another thing to reduce heat from turbo is external wastegate, that gas never sees turbo and hopefully help reducing thermal load a bit.
What method would be dependaple way to monitor the heat? EGT? Water and Oil temps?

What can be done if I find this turbine is too small and I could use bigger housings, can they be bolted on or do I need new turbine too with rebalancing.

hrk

I use an EGT and it has dependably relfected my changes in fuel and ignition settings while tuning. It's installed in the collector, about 1" from the turbine housing mounting flange and the tip is centered in the collector.

If you used a turbine housing with a standardized exit setup (like a Vband) you could easily swap housings out. You could even swap out housings to better match the application. Say for track events "drop in" your bigger turbine housings. Since you're starting from the ground up, you could "engineer" it for simplified swaps. - rob

As M2 states, a Type-K thermocouple (aka EGT probe) is the most commonly used and accepted method for measuring EGT's, it's usual mounted right at the turbine inlet (hence the name T.I.T. *Turbine Inlet Temp*.)

Mark

Manifold mocked up:
http://russmarshall.com/v/cars/cmc7/...10900.JPG.html

Turbo kinked a bit to get straighter shot for exhaust.

hrk

:edited hotlink away

Nice. This is quite exciting. It looks as though you're building the track car that will whoop up on the big dollar machinery... your intent? You need a front hoop so you can cut loose in SPU - no? :eek: When do you think you'll be on track? I've got a got some Miatas lined up for Rd. Atl track events in 07- hope you're there... would hate to miss the debut.

:redx:

not to be ---- but isn't the GT28R now GT2560R? The GT25R is now GT2554R?

Anyways from the pics it looks to be the GT28R. It should spool fast on your 1.8.

Thanks Tim for pointing that typo out. GT28R is what the turbo should be, but I'll check the part number and measure the wheels to be sure.
"For those familiar with our product range, this means that the unit formerly known as "the GT28R" (part number 466541-1) is now in the GT25R family. More specifically, it is now a GT2560R model."

One concern is that this turbine housing is marked .48, where can I get bigger ones in case it is too small for track use?

Thanks Rob for the idea of swappable turbine housings. I have kept that in mind and the placement of the turbo should allow it.

The exhaust will have 4" long cone from 2" to 3" and then few 45 degree bends and a muffler of some kind.
The wastegate needs to be figured. Is there a problem bolting the Tial upside down very close to the manifold? Heat?

Yes, this car is trying to keep up with fast cars there. So far it has been fine, only straights give troubles. 116 mph doesn't cut it in Road Atlanta.
It has full cage and would be good for SPU as it is and SPO after turbo. No funds to race in both SCCA and NASA. The latter has a class for these (and turboed Miatas too if one would like to do time trials or wheel to wheel racing)
and the schedule can be found:
http://www.nasa-southeast.com/schedule.jsp

hrk
hrk

Orientation of the WG isn't an issue. But consider its location with regards to exhaust flow. On a log... its not really that much to think about, but keeping it more central will allow it to regulate the gases better.

ie: don't put it on one end of the header :p

Ok, Time to revive old posts.
Story continues and so will questions.
Where are you guys picking up boost signal for electric boost controller?
I saw some referring to pick it up from manifold, but I would be worried of stessing the turbo and intercooler pipes if I am modulating gas in corner with throttle and the poor turbo is pudhing against partly closed throttle with all it can give.
Should I put it right after turbo?

hrk

I have a fitting on my compressor housing with line that T's off to the wastegate then to the EBC solenoid. Then the other side of the solenoid connects to my wastegate. That's for a tial external gate, not sure what you're using.

Edit: Just went and looked. I would drill and tap the compressor housing or my IC piping that way you don't have a long vac line coming from the intake mani all the way to the other side of the car.

If you are modulating mid-corner, there will not be enough mass flow to generate massive boost pushing against a closed throttle. The throttle is the ultimate boost controller, not RPM.

hrk, on engines I do for circuit with external w/g, the actuating line (closest to the valve) goes to a boost/vacuum source. When the throttle is closed, it pulls the BOV (right next to the throttle) open, and the w/g closed. Keeps the air-stream moving in the correct direction, and keeps what exhaust pressure there is on the turbine to keep the rpm's up. If you have misfire capability, throttle/power response will be almost identical to an N/A engine. If you like your turbine, and don't use the anti-lag, it still works very well. The upper part of the diaphragm (farthest from the valve) goes to the boost controler on a boost-only source. If you run that off of a vacuum source, it will try to pull the valve open during decel.

not really a comment but more of a question, bravo sir. thats sexxy.

for motorworx: could you explain boost/vacuum source to me? and also when you say "upper part of the diaphragm" what component are you talking about the wastegate or bov?

Im a little confused... when you say *source are you talking about a fitting on the IC pipe/manifold/ect that feeds a boost signal? or are you talking about some sort of vac canister that I have no idea about?

I know its not my thread but I like to know what you guys are talking about :)

boost/vacuum source means after the throttle and before the valves. Someplace that you can reference vacuum as well as boost. I am only talking about the wastegate (w/g). The source must react instantly to changes in the intake manifold; under boost, it wants to push the w/g valve open, under vacuum it wants to pull it shut. External waste gates have an upper and lower port. When hooked up correctly, they are in what's called "stand-off", where the boost trying to push the valve open "fights" the boost on top (lower because the controller limits it) keeping it closed. When hooked up like this, boost response is much faster.

Thank you for your comments!

mschlang: I was thinking along same line about the boost, but was worried about spikes, or gradually releasing throttle.

I do have Tial with two ports as my external wastegate, Tullos electrical boost control and GM boost control solenoid.
The way I understand cjernigan has his set up is (please correct if I am wrong):
- if boost control solenoid is wide open both sides of wastegate sees the same pressure and stays closed.
- if boost control solenoid is closed the boost affects only to lower side of wastegate, allowing it to open.

The way Motorworx describes the lower side can have boost or vacuum, and the upper side can only have boost if boost control solenoid is open, if it is closed then the pressure from below (manifold) opens the wategate.

Now that brings me to another question:
Assume boost controller closes the valve at 10 psi.
Car is gradually bringing the boost from 9 to 10 psi. At 9 psi both sides of wastegate actuator sees 9 psi and nothing moves. Boost builds. At 10 psi boost solenoid closes. Where does the pressure on top of actuator go to allow the bottom pressure move valve? Is it vented to atmosphere with GM solenoid somehow? If not the pressure differential between the top and bottom part of the WG actuator remains quite small and WG doesn't open.

Hope this makes sense.

hrk

HRK- Sounds like we have the same setup as I too have the Tullos and GM solenoid.

awesome thanks, I didnt know some wastegates have 2 ports, thats really cool to know.

I was pretty sure the about the boost/vacc source. but, better to ask a dumb question than make a stupid mistake.

The answer to my own question is: GM boost solenoid vents to atmosphere, so the pressure is released and wastegate can open.

And to another question:
The first road race in Saturday and I'd like to start carefully and use as little boost as possible. Basically I consider this as a test day for next months outing in Road Atlanta.
However I have 7 psi spring on wastegate.
Is there simple trick to lower that rate?
I have stock 1.8 (230cc/min ?) injectors and RX7 460 cc/min ones.
As you might think, there is very little time for testing between today and Saturday, and I'd like to keep variables minimum this time. How much boost can stock injectors handle and can I get wastegate opening that low?

Thanks
hrk

Your EBC should let you run 3 psi using the Tial and GM solenoid. If not 3 then i know you can run 5 because i have on my similar system and the 1.8 injectors work just fine for that much boost. That's been my experience atleast.

Well, how does the EBC make 3 psi pressure if the spring is open fully at 7 psi?
Is the Tial open partly at 3 psi?

hrk

That's what I was wondering? How can the EBC solenoid decrease wastegate pressure?

Well guess i don't have any documents to back that up.
I have a 7psi spring in my Tial when run with just a signal line off the compressor it ran at 7 psi all day long on my boost gauge.
I installed the Tullos and ran it at the default which is 5 psi. It would read up to 5psi and never any more. I guess i didn't take into account the possibility of the two pieces(gauge,controller) reading the same amount of boost as different pressures. So it's very possible that i was actually still running 7 but the tullos controller was saying i was at 5. I would test it more and back myself up but the damn car is grounded so i can't. If i can back myself up later i'll post why. I thought that the solenoid would bleed signal pressure allowing the WG to open at lower pressures than the spring was rated for but like i said could be wrong. Sorry

So yeah now that I think about it I was pretty much not thinking straight when i said that. Anyway i don't know any way that you could easily get the WG to bleed boost at lower than 7 psi. Tial has a 3.6 psi spring available and that's as small as they go. I don't think you can shim, cut, heat that spring to any extent that you'll be able to achieve an accurate lower boost value.

I dont think the ebc can... unless it has a tiny compressor to feed the wastegate the spring pressure on command...

as far as I know the only way to do this is to swap out the wg spring.

Yeah definitely no tiny compressor in the GM solenoid.

Your GM MAP sensor just reads and outputs [to the Tullos] a different PSI reading than your boost gauge. That's how my EBC and boost gauge are.

Big thanks to all who helped getting the car to the track last weekend. WOT and Bandit for parts and numerous other people for advice.

Some random photos of getting the car ready here:
http://russmarshall.com/v/cars/cmc7/...rbo/?g2_page=1

Weekend story is written here:
http://russmarshall.com/v/cars/cmc7/cmpfeb2007

There will be in car video once I get it out.

:edit
In meanwhile here is a link to a video from Thunder class Corvette Z06
http://video.google.com/videoplay?do...17523305208352



Some issues, but there was a steep learning curve.
See you at Road Atlanta March 17-18.

Even untuned, 7 PSI, base timing 6 degrees, and stock injectors maxed out the car was a beast! AFR kept 10.9-12.3 below 6500 rpm under load. Above 6500 it went lean quick and made me pull back throttle.
I quess I need to dyno tune this one so I get some sense to ignition timing.

hrk