1999 Tahoe Twin turbo project

[ice3186]

Hey yall i am twin turboing my 199 tahoe with two T3-super 60. I am custom building my own piping and intakes. I would appreciate any opinons that you ahve about a couple things: 1.) do i need to upgrade my ignition system? 2.) are there any tweaks that i may not know about taht i would need so that i dont blow my engine up. I would appreciate this a lot yall. Thanks for taking the time and if you want i will try and post or send you all some pictures if you want them.

[pre98zetec]

Your engine will not handle that , you will need sum serious internal work, IMO for the engine to run good with the turbos installed. and WHY?? i see a fast SUV as usless, its a top hevy POS. IMO...

[SaabJohan]

I would have recommend a newer turbo like MHI TD04 or Garrett GT instead of the older Garrett T3.

I don't know anything about that engine, but in general it's very important that the engine get the fuel it needs. A good intercooler is also important.

I would also have "matched" the turbos for the engine and power output (not only use what you have).

A lowered compression can be recommended.

[krebs128]

Originally Posted by sk8ter_in_ny

Your engine will not handle that , you will need sum serious internal work, IMO for the engine to run good with the turbos installed. and WHY?? i see a fast SUV as usless, its a top hevy POS. IMO...

he could use smaller turbos, like a pair of t25's, less boost but won't have the risk of overboosting your engine, and wastegates and blow off valves will also contribute to preventing overboost and damage to the turbo and engine. don't forget u'll have to re-do the fuel injection of your engine-more air will need more fuel. new chip would help, turbo timer, and computer controllers.

[ice3186]

hey yall i was worried about overboosting the engin but taht problem is easily overcome but just using the correct boost controller as stated. As for using a GT series Garrett that is way out of my budget but i would like to. i know that i need to upgrade the fuel pump but i dont know about the rest of the fuel system?

[krebs128]

yea, you prolly should. you would be getting more fuel to the injectors by installing an aftermarket fuel pump, but once it gets there it'll be limited due to the stock size-they wouldn't be made to handle such an increase in fuel needed to keep a proper air/fuel ratio.

[ice3186]

any recomidations for what fuel system to use?

[krebs128]

i don't know of any comanies that make aftermarket engine parts for tahoes. ask your dealer if they would recomend any companies that sell larger injectors. GM might make some, they do for cavaliers, check their site: www.gmpartsdirect.com

[Sluttypatton]

First off, what method of fuel correction are you planning on using? You can't just toss in a bigger fuel pump and hope it works. You have to decide how you are going to correct for the increase in air.

[SaabJohan]

First, what power does the engine deliver? How much power do you want after you have added the turbochargers? From this we can get an approximation of what boost pressure is needed. Then we can calculate the airflow needed. From this we can match a compressor size.

With diffrent sizes of turbines and turbinehouses we can change the rpm when the turbo kicks in and the flow restriction at high flows.

I have no idea what a tahoe delivers originally, but for exampel, if we want 300-400 twin Garrett GT17 should do the job, for 400 hp and up we can use twin MHI (Mitsubishi Heavy Industries) TD04 turbochargers. TD04HL-15T-5 should be right for 400-500 hp, we can get up to 750 hp by using twin TD04HL-19T-7.

Garrett GT17 can be found from around $200 to $800, MHI TD04 from around $300 to $800, $800 is what they cost new from the manufacturer. GT and TD04 are superior to T3 and T25, they kick in earlier, have a faster spool-up and are more efficient (since they are newer designs).

The fuelsystem must be modified. A pressure regulator must be fitted so that we get a constant pressure difference from fuel system and inlet manifold. We must add a fuelpump that can handle the extra flow needed, or we can fit it with an extra fuelpump, a Bosch pump will work fine.

Fuelinjectors can be stock or larger, depending on what power increase is wanted. Bosch and Siemens are two examples on manufacturers of injectors. Injectors can have low or high resistance (ohm), use the types used originally.

The turbochargers have internal wastegates that will control the boost pressure. A bypass valve should be used to protect the compressor from choking when the throttle is released.

The electronic management system must be modified, how this should be done depends on the oem system.

[ice3186]

okay well i ahve no idea about what a pressure regulator is and i will look to see if i can find any other turbos that will work but i am trying to make this as cost efficent as possible. My truck puts out a stock 255 BHP is 350ci 5.7l V8. so if tyhat helps at all then i hope so. I was already planning to put in a Bosch pump and injectors. soo..

[SaabJohan]

Originally Posted by ice3186

okay well i ahve no idea about what a pressure regulator is and i will look to see if i can find any other turbos that will work but i am trying to make this as cost efficent as possible. My truck puts out a stock 255 BHP is 350ci 5.7l V8. so if tyhat helps at all then i hope so. I was already planning to put in a Bosch pump and injectors. soo..

Fuel pressure regulator, regulates the fuel pressure. If the fuel pressure at 0 bar boost (1 bar absolute) is 3 bar, the pressure should be 4 bar at 1 bar boost (2 bar absolute) and so on.

With 255 hp you can probably get 350 hp without changing compression ratio, or higher if the compression ratio is changed.

[ice3186]

well my compression ratio is 9.4:1 so i dont know how muc that will do for me and if i do need to get a higher compression ratio, how would i go about doing that

[SaabJohan]

Originally Posted by ice3186

well my compression ratio is 9.4:1 so i dont know how muc that will do for me and if i do need to get a higher compression ratio, how would i go about doing that

It's diffucult to say if the compression ratio needs to be lower, it depends much on the combustion chambers, fuel injection and what octane rating going to be used. To be on the safe side, the compression ratio should probably been lowered somewhat, maybe to 9,0:1 or a little under that. With a good intercooler on that i think 1 bar of boost should be possible.

I would suggest that material is removed from the combustion chamber in the cylinder head, material from the piston crown can also be removed with a lathe but that will also weaken them.
I don't recommend thicker head gaskets or removal of material on the piston crowns in the squish zones.