rnjmur

I'm not saying that having an LS and dusting a SS/SC wouldn't be cool, I would be thinking - what the hell? - but by the time you turbo the car you really aren't saving that much money. I would love to see a turbo LS or LT hang with me in a run - it is a tribute to the fact that these cars have lots of potential.

Halfcent

A "piggyback" is a computer that is put in-between your stock computer and the car. It modifies the signals sent to your computer to trick it into doing what you want. The problem with our computers is they set of the CEL if you sneeze wrong. It will know something is up and start throwing codes.

Alpine uses the SMT-6 model piggyback. It is capable of controlling your injectors directly as you suggest. Alpine chose to do the 5th injector idea. I think it's a horrible idea due to the plastic intake manifold.

rnjmur

You still need to be able to tune for AFR. If you just slap in 60 lbers the computer will think they are the stock injectors.

TCarter

Once more people get the alpine kits, I know Alpine will start to fix the problem. Im sure Alpine ran it for only so long before releasing it...and during that time Im sure it worked like it should have.

But, it also leaves room for vendors (like me) to produce a more reliable intake to replace the plastic one in the kit, yet still work the exact same way.

Sw4y1313

Before you guys "assume" it was fuel that cuased the manifold to break, why dont you WAIT until i get the F'ing manifold outta my car so i can tell you what caused it. Sick of you stupid kids assuming ****....

LewiSS

Don't yell at ME! I took it all back! I think it popped like a balloon!

Let us know what you find out. I've been scheming of ways to reinforce the stock manifold. Carbon fiber vacuum-bagged to the existing manifold? Hmmm....

laserelectric

Alright, I see you are a sales associate from the tnt page...I am VERY glad you are on here, you may be able to answer the questions:
What is the point of the fifth injector?
What are pros and cons of the piggy back?

Also, could use some support as to why you suggest this kit? Sorry, I need porfessional advice?

Jake S.

got a few questions is the 07 ls balt tuneable and are there any tuners, second is the alpine kit worth buying or do i want to do a engine swap off a ss? if i swap engines it will be 2.0 sc tranny and ecu

LewiSS

When an engine is "boosted" (additional air forced in by a supercharger or turbocharger) more fuel has to be added or the mixture will be lean. A lean mixture is a bad thing - it destroys engines by breaking pistons. To add the extra fuel, the Alpine kit uses a fifth injector that is only triggered when the car is under boost (when the turbocharger is making positive pressure in the manifold). It is controlled by the piggy-back computer, which monitors manifold pressure and triggers the injector based on boost (it's not just off or on, like early systems - the piggy-back controls the duty cycle of the injector to send the right amount of additional fuel to match the boost).

Additionally, when this fuel and air enters the cylinder, it is much more dense than it would be if there were no turbocharger. A dense air mixture burns slower than a less dense one. So the spark plug needs to be fired earlier. This is called retarding the ignition. The piggy-back computer, when it senses boost, alters one of the signals to the stock computer, causing the computer to retard the ignition based on the amount of boost.

The first change, increasing fuel based on manifold pressure, should be possible using HPTune software to alter the stock computer programming (on the 2.4 - not available on the 2.2) and larger injectors. If that were all that were needed, there would be little need for the piggy-back on the 2.4. However, I'm not familiar enough with HPTune to know if you can set a parameter that will cause the timing to be reduced under boost.

For the 2.2, since HPTune isn't available, it becomes a moot point - the piggy-back computer is the only option. Running a turbo on a 2.2 without some form of tuning (like a piggy-back) will kill the engine eventually (probably sooner rather than later) due to lean mixture and detonation (pinging) breaking up the pistons. Note that one issue with the Ecotec is the distance from the top piston ring to the top of the piston is VERY short compared to other cars, making the piston very vulnerable to breaking the edge in this area from pinging.

In my opinion there are few cons to a piggy-back, but halfcent feels differently. I can't speak for him (jump in here, halfcent!) but I believe the concern may be the fact that you're wiring into the stock wiring, and the connections may be vulnerable to corrosion or becoming loose. Also, the quality of the piggy-back computer itself may be a problem if it's not at least as well made as the stock parts in your car. As for tuning, if a shop is good at tuning the piggy-back, I don't think it will be much worse than someone tuning with HPTune.

Cons of the fith injector are less vague. You're putting fuel into the intake manifold - a plastic manifold that was not designed for fuel. I would argue that these types of manifolds were used on carbureted engines where the fuel is mixed with the air before entering the manifold, and I would also argue that blow-through carbureted systems, where pressurized fuel/air mixture is blown into the manifold have been around (even on some exotics like the Lotus) with good results. However, there has probably never been a pressurized stock car with fuel and air entering a plastic manifold, so there is a possibility this may be a problem. At higher boost, the manifold will split at the seams, and I don't think the fuel has anything to do with it. But, since there is fuel in the manifold with a 5th injector, there is a chance of a manifold explosion. If you've ever seen a Top Fuel car blower explosion, it's similar (although gasoline isn't nitromethane, thank goodness).

The piggy-back can be used to increase the fuel at the stock injectors (you should increase the size of them) and do away with the fith injector. Since Alpine doesn't believe there is a problem with the fith injector, they don't take this approach. But it's entirely possible.

I like the Alpine kit because it was designed originally to be the factory performance kit sold by Saturn for the Ion. Therefore it's pretty much "factory quality". I like the exhaust manifolding and the "intake hat" castings. Plus, Alpine has sold over 29,000 turbo kits from South Africa, since they developed the factory stuff for many manufacturers such as Toyota and Hyundai. I believe they know what they're doing.

Plus, in my case, their US shop is about 2 miles due north of my house, making them incredibly convenient for me

Jake S.

so you think the alpine kit is a good addition