bascho

MadDog, he stated that he expects boost to come on at 3500rpm.....it sounds to me like understands the lag issues. He purposely chose a fast spooling turbo to compensate for the lag time of the rear mounting location. Are you saying the 3500rpm is unrealistic with his turbo choice and location? I have read a lot of your posts so I know you know what you're talking about. My question is sincere not argumentative.

staticlag

Crap, my bad. I was thinking of entropy. Looks like my prof. is the one crying.

rkostolni

What you guys appear to be talking about isn't even lag, as you keep calling it. Lag refers to the time required to build boost when you punch the throttle at an rpm above the minimum rpm required to make full boost. What you are in fact refering to is commonly called boost threshold.

Second, this boost threshold you are talking about is largely negated by just resizing the A/R. However, actual lag would be considerable because of all the piping to pressurize.

Personally, I think its very gimmicky. The only benefit is that its unusual.

rkostolni

Also, MD is right. If the A/R is constant, the turbo will spool faster the closer it is to the engine. What moves a turbine? What moves water, gas, electricity thought a conduit? Pressure differentials. The pressure right out of the engine is higher than after 8ft of exhaust pipe because the gas is hotter right out of the engine. P=nRT/V. Increasing the pressure acting on a fluid as it is being forced through a nozzle, will result in that fluid having a higher velocity as it exits that nozzle.

The density of the gas is somewhat irrelevant. Only the total mass that passes by it matters, and that is constant regardless of where you place that turbo within the exhaust stream. You can pass more dense mass more slowly or less dense mass faster and it results in the same effect since the momentum imparted to the wheel will be the same. p=mv. Since mass is constant, we can only adjust the velocity.

Please send all gratuity to my paypal account: rkostolni@paypal.com

rotorocks

Just an update:
I am shopping for materials.
Got myself 10 feet 2.5" plastic pipe for prototyping of the intake pipes for $7.00 as well as some 2.5" steel exhaust tubing at local AutoZone with bends and connectors. I'll use a gas torch to "glue" the metal pieces together. Right now I am planning a trip to a local metal works shop to see if I can pick up some aluminum tubes.
Keep up the discussion it is a very cool read.

Yes I may be mistaken in my logic, as gas behaves differently from liquids.
My bad. But I am doing it anyway. If they could do it, so can I.

Trekk

500 for a manifold sounds about right. 1500$?? is it made from platinum. I know a few shops that will craft any manifold for 800$, but a RX8 manifold doesnt really need any bends so it should be cheaper.
500-1000 for a down pipe? I can get it for 200-300$ manrilbent easy.
300-600$for pipes..maybe depends what he uses, how long, how many bends.
intercooler,wastegate and blow off, can all be had really cheap.
Blow off from a first gen eclipse runs about 50$, its metal and can hold 15psi easy. you can even drill into it so it will hold more.

I've built a few turbo kits for civics and toyotas, so I have a good idea what prices run and where to get the stuff.
Like I said before, you dont need top of the line name brand stuff. It all works for low to med boost. He could always upgrade later. He wants to build it cheap and its not impossable. Used EMS wouldn't be super hard to find or alot of $$, someone that can tune it right might be.

If he fails he fails, the stuff will sell reguardless if he needs to get rid of it. Don't tell him he can't do it cause he will be able to if he tries hard enough.

rotorocks

Guys,
A quick question:
I got a 40mm external waistgate off eBay however it comes without the dump pipe flange. What size flange do I need for it? The flanges I could find are either 38mm or 50mm size. Will 38mm fit, or should I look for a 40mm (though there are none I can find of that size)

MrWigggles

If you needed heat to for a turbo to work these guys would be out of business:

http://www.ststurbo.com/

The idea that you need the turbo close to the engine to reduce lag is correct. The idea you need heat for a turbo to work is wrong. And don't forget a hot turbo means hot intake temps.

Rotorocks, sizing your blades for your turbo is going to crucial for it to work. Your turbo will work with colder air, but the blades have to be sized correctly - the current fitment is likely expecting hotter gases and won't work well with cooler gases you will be giving it. Don't ask me what trim you need; the science and art behind that are beyond me.

I don't think you will get in trouble for your own personal build but the STS design is patented. I'm not sure how inclusive their patent is, but don't think about selling your design when you are done. They could pull you into a federal court to defend your design. Even if you prove your design doesn't violate their patent, the court costs will eat any profits you had hoped for.

In other words, this is going to be one time deal for yourself. Good luck,

-Mr. Wigggles

globi

True, if you're talking about water turbines.

I don't think this was the argument. To work you don't, but to generate more power with a given exhaust flow you do.
If STS was in the racing business it would indeed be out of business. However STS is not in the racing business nor is this particular car we're talking about and it will work just fine.

globi

Mass flow going through the compressor wheel is generally the same as mass flow going through the turbine. So, if it was indeed mass flow that matters and not enthalpy, a turbo could pump water from its compressor wheel to its turbine wheel all day long - a technique which for instance could be used to run a shower at a lake without needing any energy to pump the water (the drain water would simply run the turbine, which in turn would run the pump wheel).

rotorocks

No it is not. Depending on the application the compressor can be either bigger or smaller. Smaller compressor will produce higher pressure, while larger compressor will be able to flow more air, but won't be able to compress it as much.
In the ideal situation (same size of compressor/turbine, absence of gravity, friction, momentum, blow by that occurs as gas squeezes by the blade and the housing wall) yes, but in real world, there are losses.

Now does anyone have an answer to my previous (waistgate related) question please ?

rkostolni

The pressure differential is required to force the mass flow. The mass flow is what forces the turbine to move. In your shower example there is no pressure differential.

globi

If the bypass is closed then massflow in = massflow out and this is regardless of the size of the compressor. Unless there's a secret intake or exhaust we all don't know about, then massflow in = massflow out.

Naturally the shower head is 7 feet above ground, so there's your pressure differential...

rotorocks

We are talking about different things. You - about the flow, I am - the fact that the compressor may be sized differently than the turbine...

Are we trying to build the world’s most efficient shower here?

rotorocks

HKS 40mm

MazdaManiac

iTrader: (3)

I say go for it. If you can afford the time and keep your options open, you might pull it off.
As long as your are doing all of the work yourself and you stick to cheap/used parts, the price threshold is between $3500 and $4700 for a complete DIY turbo system.
However, expect to sink that much again into it over the duration as you see the potential for more.
You might want to check my threads/site on this sort of thing since I've already done it before.

BaronVonBigmeat

To compare apples to apples, we should probably include the cost of a catback into the price of whatever conventional setup we're comparing, because if he's doing an STS style setup, he won't need one.

rotorocks

I am putting in a couple of cherry bombs, though. $26.99 a piece, can't beat that. Guys, you'll be surprised how much stuff can be purchased for $600 on ebay.

$31.99 OIL RESERVOIR CATCH TANK MAZDA 6 RX7 RX8 MX-5 Brand New
$14.78 T3/T4 Turbo 2-1/2" exhaust downpipe weld flange steel! Brand New
$70.00 40mm HKS Turbo Wastegate 16 PSI Brand New
$14.78 T3/T4 Turbo Inlet manifold Weld Flange 3/8" Brand New
$439.98 T3/T4 T04E TURBO KIT+GREDDY BOV+BOOST CONTROLLER+INTERCOOLER Brand New

All prices are final and include shipping. This is what I already prchased. Once I get all the parts together, I'll take some pics :-)

rotorocks

Update:

Got most of my parts in already. This weekend I'll start trying to fit things in little by little.
Will begin the works on putting together the oil transfer mechanism.
I had decided to run a copper line from the engine down to the turbo. It can be picked up in the Home Depot In the plumbing section for cheap, plus will provide additional oil cooling. So when oil gets to the turbo, it’ll be nice and cool. The return oil will pour into a custom build container from where it'll be pumped out and back into the engine with a 12V electrical oil pump.

Question, is dumping oil through the oil cap a good idea or is tapping the pan required?

Nemesis8

iTrader: (3)

I bought the same one off ebay for $12

evilmiata

Oil coming out of a turbo is foamy, and most setups naturally have the oil pan directly below the turbo. I GUESS you could pump it back through the oil cap, but I certainly wouldn't want to be the one who does that experiment on their engine for the first time. Do it right and tap the pan.

BTW, a 16# spring in your wastegate is a bad idea. Its best to have a more sensitive spring coupled to a boost controller; you'll get more accurate tuning and the opportunity to set boost below 16#. Your wastegate will never open until 16psi!

rotorocks

Progress Report:
Though I am busy at work and at home, little by little I am moving forward with my project. I have completed the purchase of all the necessary components. All of it together with the Int-X cost me just under 3K.
Intercooler is installed. I had installed it by welding two thick steel brakets to the bumper brace and placing it at a 45 degrees angle (similar to the radiator, but about 10-12 inches in front of it. I had to cut out some of the plastic ducting to allow for better airflow to the radiator, and it seems to work well, I was driving with it (no plumping) real hard for a couple of days, to see if the car will run too hot (close to 100F outside today here in south FL), but there are no problems as there is plenty of air coming in through, above and around the intercooler.
You can't even tell there is a huge intercooler in the car, as it is almost invisible from the outside.
I am taking pics of everything, so as soon as there is some decent progress, I will post them.

To make the install easier, I had purchased a used RX8 muffler on ebay. The thing is huge, has all the necessary mounts already in place, so I decided to gut it, cut a bunch of ventilation openings, cut out everything I don't need and put all my components inside of it. This will make everything very compact, allow me to completely assemble everything on the hot end (and partially the Intake tubing) while it is off the car, and will be very easy to install. It will also allow me to keep the air intake right there, as the filter will be protected from water by the muffler core.
I had finally decided to go with an internal waistgate. (the external HKS that I had purchased is too huge and will be a major challenge to fit inside the muffler body along with the turbo, intake, filer, the oil return can and the oil pump.
This is it for now.

rotorocks

Here are some pics of how the turbo will be fit inside of the exhaust case. (the exhaust is upside down by the way)

gh0st

WOW...this is going to be interesting. youve got some major cajones man.