small turbos, low boost, external wastegate?

[pitbullgst]

hey are their any small turbos that use external wastegates i could look for in the junkyard and on ebay? all the ones i see of decent quality are intregal wastegated.(mitsubishi, garrett, etc...)? I would like to start turboing some of the 4 cyclinder daily drivers but with low boost set around 7-8 psi. any info or advice guys?

[-Jayson-]

7-8 PSI on a 4 cylinder is more so moderate boost. That will require fuel modifications in the form of bigger injectors, fuel rails, pump, and some kind of fuel regulator as well as a good amount of tunning. Low boost on 4 cylinders is more like 3-5 PSI.

[SaabJohan]

Most small turbochargers have integral wastegates, but if you want to use an external wastegate you can buy a new turbine housing for the turbocharger without a wastegate.

[nissanfanatic]

7-8 psi is going to be making 50% over stock power.

[beyondloadedSE]

Originally Posted by -Jayson-

7-8 PSI on a 4 cylinder is more so moderate boost. That will require fuel modifications in the form of bigger injectors, fuel rails, pump, and some kind of fuel regulator as well as a good amount of tunning. Low boost on 4 cylinders is more like 3-5 PSI.

do it right, and do NOT raise the fuel pressure. Get bigger injectors, get it tuned. Nuff said.

[-Jayson-]

Originally Posted by beyondloadedSE

do it right, and do NOT raise the fuel pressure. Get bigger injectors, get it tuned. Nuff said.

isnt that what i said?

[beyondloadedSE]

Originally Posted by -Jayson-

isnt that what i said?

Originally Posted by -Jayson-

, fuel rails, pump, and some kind of fuel regulator as well as a good amount of tunning.

no. your telling him to get a fuel pressure regulator. im telling him not to.

[nissanfanatic]

If these are just little beater cars that you're messing around with, go with a FMU. Especially with those little turbos, you're not going to be making much more power at 7psi. I said 50% more earlier, but that is just a pressure ratio HP calculation. I don't know what a T25 flows at 7psi, but I know that a 240sx makes 155hp stock and the fuel system isn't even capable of supporting 200hp. But it can support a T25 at 8psi on the stock fuel system. When you do bigger injectors and a piggyback, you begin messing with MAFS or MAP voltage. Either of the two are not good for stock closed loop. After a while, the factory settings take over your programmed settings and can cause you to lean out at part throttle. Especially bad for a small turbo like that because it spools quickly and probably in closed loop. 14.7af is not good at 7psi. And not only do you affect the fuel map, messing with MAF voltage also puts you into different sections of the timing map. And good luck controlling timing after you do that. Emanage would be a good alternative to this. But I'm not saying it won't work or won't work well. I'm just pointing out the potential problems. ECU retune will put you around probably all that mess. Or you could go full stand-alone which would be optimal for performance. But these are just daily drivers that will be making 150whp tops eh? Not worth the money. And you will need to spend money on a wideband. Don't tune without one. Do yourself a favor and just use a FMU. If you aren't sure on AFs, take it to a dyno and see how its doing. And fire hazards? Most stock fuel hose is rated at 300psi. Hose clamps on the conecting points and new injector O-rings will suffice.

[duplox]

Originally Posted by beyondloadedSE

no. your telling him to get a fuel pressure regulator. im telling him not to.

All cars have fuel pressure regulators, turbo'd or not. If your car wasn't turbo'd from the factory, chances are you NEED a fuel pressure regulator just to keep your injectors firing consistantly. There are several kinds, two are appropriate for boosted applications - boost referenced 1:1 ratio regulators and boost referenced rising rate regulators. A 1:1 regulator increases fuel pressure 1psi for every 1psi of boost. This kind of regulator keeps the ammount of fuel being injected consistant regardless of boost. If you don't have a boost referenced FPR and run boost, in essence your injectors are seeing less fuel pressure. If you are running a stock 43psi fuel pressure and 15lbs boost, your injectors 'see' 43-15 = 28psi fuel pressure. Not good. With a 1:1 ratio regulator, it will add 15psi to your fuel pressure when boost is 15psi. So you'll have 58psi-15psi = 43psi. Much better.
A rising rate FPR increases the fuel pressure more than a 1:1 ratio.. the specific ratio can be set on the FPR. This is meant to overcome the need to have the computer remapped, since with more pressure, more fuel per injector duration. I suggest getting a 1:1 ratio FPR and having your computer remapped on a dyno.

[nissanfanatic]

Acutally most modern cars use a FPR that is referenced to manifold vacuum. After you pass 0" HG, it goes to a 1:1. Best way to see is a fuel pressure gauge and a pressurized air source.

[beyondloadedSE]

Originally Posted by duplox

All cars have fuel pressure regulators, turbo'd or not. If your car wasn't turbo'd from the factory, chances are you NEED a fuel pressure regulator just to keep your injectors firing consistantly. There are several kinds, two are appropriate for boosted applications - boost referenced 1:1 ratio regulators and boost referenced rising rate regulators. A 1:1 regulator increases fuel pressure 1psi for every 1psi of boost. This kind of regulator keeps the ammount of fuel being injected consistant regardless of boost. If you don't have a boost referenced FPR and run boost, in essence your injectors are seeing less fuel pressure. If you are running a stock 43psi fuel pressure and 15lbs boost, your injectors 'see' 43-15 = 28psi fuel pressure. Not good. With a 1:1 ratio regulator, it will add 15psi to your fuel pressure when boost is 15psi. So you'll have 58psi-15psi = 43psi. Much better.
A rising rate FPR increases the fuel pressure more than a 1:1 ratio.. the specific ratio can be set on the FPR. This is meant to overcome the need to have the computer remapped, since with more pressure, more fuel per injector duration. I suggest getting a 1:1 ratio FPR and having your computer remapped on a dyno.

what im saying is raising the fuel pressure instead of upgrading injectors is a piss poor way of doing it.

[Schister66]

Whatever, get a t25 turbo kit and you'll be happy. If this is a Honda, you could run 5-8psi and not change a thing. I wouldn't recommend it, but i've seen stock Civics running 12psi with only an Emanage or Hondata system, larger injectors and the kit done. They didn't need a larger fuel pump or fuel rails or any of that stuff. IMO unless you're going all out, you don't need the smaller stuff because you aren't pushing enough power.