Turbo conceptual question....

[Akula]

Lemme see if I got this right, when turboing a car.

 

I am thinking about like picking up a police cruiser at the auction, or getting a camaro that needs a motor, so I am talking V8 turboing.

 

I have to have a manifold off the exhaust that gets the turbo spinning. This in turn gathers cold air and blows it with force into the motor. You can run the air it is blowing into a FMIC or some such to cool the air (more O2). A dual turbo is probably the easiest for a V8 application, no?

 

So lets say I am blowing this air into a carb, I would have to have the carb running richer than a non-turbo application, right?

 

If I am running this into FI I would have to have a bigger throttle body and higher duration injectors to get more fuel in the air/fuel mixture, right?

 

I have never slapped a turbo on anything so I am trying to figure out how hard this would be.

 

How do I regulate the PSI, it seems the boost would always be increasing. I would be building this for a dragstrip so I need to keep it consistant.

 

If I am missing a big part of this, let me know. This may be a good thread to show those that don't know (like me) how to tune/setup a turbo.

[Doug1647545489]

Wastegates regulate boost. They open and allow exhaust to bypass the turbine.

[Akula]

So they operate on the output of the motor, not like blow off excess pressure in the intake airstream?

[Hwilli1647545487]

I'll try my best to explain.

 

Turbos are basically two fans on a shaft. One side (the hot side)is spun my exhaust gases. This in turn spins the shaft, which spins the other fan. This other fan (the cold side) is attached to the outside, it gathers up outside air and compresses it. This in turn goes to your intake.

 

Basically you are artificially raising the compression ratio of the motor. More compressed air particles.

 

As far as your carb comment, I don't know dick about carbs, so I am not sure how you would control fuel with boost. With EFI, people normally run a variable rate fuel preasure regulator. That will increase fuel preasure xxx per pound of boost. Also you have ECU tuning to control the fuel injectors.

 

The amount of boost each turbo will push is controlled by the wastegate. The wastegate is kind of like a valve. It will control how much exhaust gas is going over the hot side fan. In this gate is a spring. The Spring has a PSI rating. That is the maximum boost the spring will hold before the exhaust preasure forces it open (and thus bleeds it off directly to the exhaust and out your tailpipe). You can trick the wastegate into thinking it has a bigger spring with a boost controller.

 

You do this by adding additional preasure to the other side of the spring to help hold it closed against the exhaust preasure.

 

Finally, the intercooler. When you compress the air it heats it up. Hot air is less dense than cold air, thus is not as effective for making power. The intercooler is plumbed after the turbo, and before the intake manifold in order to help cool down that heated up air.

 

I hope this helps. I'm sure Brett or someone else will also pipe in smile.gif

 

 

Howard

[Lustalbert]

on a v8 aplication, i would go twins.

In order to flow enough air on a v8, a single turbo would be quite large, and would take time to spool up.

you can do it with a carb. You will need a rising rate fuel pressure regulator, and an electric fuel pump. You will need to plumb the perussure port on the regulator to the top part of your carb (before the throttle plates) otherwise you will not be getting any fuel into the carb (carbs usually only run about 4-5 psi fuel pressure) and the fuel bowls need to be at the same pressure as the air coming into the carb or else the pressureized air will prevent any fuel from flowing though the jets. You can run your primaries at a nomal mixture, and run your secondaries righ (youll probably only get into boost when you are getting into your secondaries anyways)

if you want, hit me up some night at krogers, or on im, ive done some research into this.

[Renner]

Originally posted by Ficus:

I hope this helps. I'm sure Brett or someone else will also pipe in smile.gif

 

 

Howard

Nope, Howard's got it covered. graemlins/thumb.gif

[Buckeye1647545503]

Ok so I have been thinking of some turbo applications and I am wondering if there are any good manuels covering choseing turbos, use of dual boost controlers, and bov. I know how to work on them and how to do a standerd bleed, but after that?????

[Guest mudbutt]

Corky Bell Maximum Boost is a good place to start.

[Akula]

So I understood a bit of this in the beginning and now it is getting clearer.

 

Where does one purchase a couple of turbos? (I assume Garrett turbos, but where do you guys get yours?)

 

I will need special manifolds for the exhaust and intake, do I have to make thos my self?

[desperado]

As far as turboing a motor. A couple of sugestions. First is to get two books, thefirst being turbocharging from HP books. Jegs sells this or I can get you a link to it on amazon.com, let me know if you need that. Second book is not something that you so much need to buy as just finding a copy and looking at it. It's the lingenfelter small block book. In it he specifically talks about a 600HP 406 that has good street manors and big block torque.

 

The easiest route to go with a turbo or a centrifical (sp) supercharger like a Paxton is an EFI motor. Reason is this. There are three types of carb setups. Draw through setups that have fuel and air in the turbo, the carb sits before the turbo. These are the least desirable. The other two are blow through designs, the air if forced through the carb. Each has it's limitations. there is the bonnet design where air is forced through the center of the carb. This design has issues with fuel leakage due to the outside of the carb not being under pressure while the inside is. Forcing fuel from any and all unsealed areas of teh carb. Fuel bowls, throttle plate shafts, vacuum line connectors and and body seals. There is a real need for either new carb, or a special (expensive) carb with shaft seals and other mods to keep the fuel in the carb and not all over the motor. The second is the box design. Where a sealed box with a hole in the bottom encases the entire carb. This is preferred as the carb is not subjected to pressure on just the inside, but instead the entire carb is pressurized both inside and out. This eliminates the fuel metering issue with the other design, as well the carb doesn't try to leak air and fuel from every seal either.

The last issue with turboing a carb setup is that fuel pressures from the pump are 5 to 7 PSI. When you presureize the floatbowls, you can only get away with 3 or 4 lb of boost before the fuel stops flowing. By 5 lb the fuel pump can not overcome the air pressure in the floats and they go dry. So a special fuel regulator is required to increase the fuel pressure when the boost goes up. This is the one of the reasons for going with a EFI motor. FI pressures are 30 lbs of better. So unless you are going way up in the boost, there is no need to increase the fuel pressure. plumbing is also much easier, with a LT1 or any multiport system, the boosted air flow can just be crammed into the air intake infront of the throttle body, and a bonnet system can be used for a single port system.

As far as twin turbos, while this is the high power setup, it's also the high cost setup. It depends on what you what want to build. Is this going to be a street dominator car with 400 HP. Or a hold on to your lugnutz, make dogs vomit 3 blocks away mill that will melt 18 inch slicks, while it twists the front subframe out of the unibody kind of thing. That is someting that needs to be desided up front, because like any motor, all desisions are made in reguards to that.

Wastegates are also sort of optional. With the proper setup, the boost will peak at the sweet spot of the motor. The problem iwth this is typically you need a larger turbo to pull this off with a slightly higher A/R ratio on the compressor side, and this will kill low end boost. The way around this is actually simpler than one might think. You simply spray the motor from off idle with a small shot, say 50 HP, then you put a pressure switch in the manifold, so that when the boost gets to a certian level, the spray goes away. It takes some level of tuning to ge this just right so an adjustable switch is desirable here. Now this stuff really applys to a twin hairdryer system, that is boosting to the 20+ psi level. Read that doggie hurl power.

Manifolds, this is with a CHevy motor made simple because you can turn them over and install them upside down and backwards with little modification. You just cut the regular ends off and weld on the fabricated turbo plumbing. And doing a single setup is also made easy because the crossover can be made in the front of the motor and not need to be routed from the back.

 

Have fun with your project and keep us informed.

[Akula]

Another question I have is, does anyone run a boosted setup on Alcohol? Alcohol is basically 140 octane gas so it can handle more compression without detenation.

 

Matt and I are thinking 383 Stroker with a twin hair dryer setup for running super pro or so at trails, maybe run IHRA hotrod.

[desperado]

From what I know about it (not alot) it's pretty much the same other than you can go to 35 psi boost without problems, the detonation factor is much higher.

[Dweet]

if you are new to turbocharging... my BEST BEST advice to you.. is to get a book called "Maximum Boost" by Corky Bell.. you can find it at a barnes and noble or whatever.. but that $35 for the book will save you ALOT of headache and possibly much more expensive damages and broken parts and whatnot.. you can get it off the internet also at Maximum Boost by Corky Bell

 

Also with a v8 application i see more people using superchargers.. if you want to go that route id recommend "Supercharged" By Corky Bell which can be picked up at a barnes and noble or off the internet.. here is the link for it.

Supercharged by Corky Bell

 

you have to remember you cant just slap any turbo on a car. there are many different types of turbos with different specs on them. also you question about carb tuning is answered in both books. the best thing you can do is get those books. it will supply you the general knowledge to safely turbo or supercharge your car and how to pick out the right size turbo, intercooler, exhaust and how to tune it with either Fuel Injector or Carbueration.

[Akula]

Thanks tibby. I have heard about that book, just wanted to hit up the guys that have put in turbos, especially if they have put in a twin setup on a v8.

 

If we ever do get this project off of the ground it will be a learning experience.

[Lustalbert]

wjenever you get around to it, lrt me know. Id like to get dirty on this one.