Tuning the Chevrolet Cobalt (Pontiac G4)

"Tuning guide to the greatest Chevrolet Cobalt modifications."

The Cobalt is a  compact car which replaced both the Cavalier and the Toyota-based Geo/Chevrolet Prizm and is a good car tuning project to do. Plan ahead and research Cobalt tuning to spare yourself making the usual tuning mistakes we often hear people complain about.

The car also wore a Pontiac G4 and Pontiac G5 Pursuit badge in some regions.

I highly suggest ordering the GM Performance Parts Ecotec sport compact performance build book (It is collectively known as the "Ecotec Bible").

Handling/Suspension upgrades

Handling modifications are a good place to start for the Cobalt.

The front Cobalt suspension has an independent setup utilizing MacPherson struts, while a semi-independent torsion beam was used in the rear.

If you set the toe out to around 1.5 degrees on the front, and add a tiny bit of negative camber then cornering will usually improve.

Drop the car by as much as 29mm - 41 mm. and fit uprated stiffer dampers, bigger drops will need other modifications in most instances.

Top end power should be your overall aim with a nice fat wide peak torque band.

Smaller engines do not provide much of a return in terms of power so start with a bigger engine. Engine swaps are a good option if you have a small engine size.

Power mods.

The following modifications are usually fitted by our members, decide how far you wish to go in your tuning project before you get started.

• 2005-2010: 2.2L (NASP)  Ecotec L61 145hp /148hp with 155 lbft
• 2005-2007: 2.0L supercharged (SS Supercharged)  205 hp 200 lbft
• 2008-2010: 2.0L turbocharged (SS turbocharged) 260 hp 260 lbft
• 2006-2008: 2.4L (n/a. SS Naturally Aspirated. 2008 models dropped the SS name and were simply called the "Sport")
• 2008–2010 2.0 L Ecotec LNF Turbo 260 hp 260 lbft
• 2009–2010 2.2 L Ecotec LAP 155 hp 150 lbft

The Cobalt was replaced in 2009 with the Cruze but the badge lives on in Brazil from 2011 replacing the Astra.

• 2011- 1.4 L flex-fuel Brazillian Market only.
• 2011- 1.8 L  flex-fuel Brazillian Market only.
• 2011- 1.5 L gasoline Brazillian Market only.

The 2.2L was never supercharged from the factory. But the set up from the 2.0L bolts right on, due to the cars having the exact same engine block.

Getting the right uprated parts for your planned usage of the car is a time and money saver. Stage 3 (competition) mods just don't work well on the road hard to control in slow traffic.

Please watch our introduction Video tutorial to car tuning. Be sure to subscribe and support our new channel.

Modifying to Stage 1:

 Lighter flywheel, Panel air filter, Alloy wheels, Remap, Suspension upgrade (drop 29mm - 41 mm.), Sports exhaust.

Modifying to Stage 2:

 Fast road cam, fuel pump upgrades, Ported and polished head, high flow fuel injector, Power/Sport clutch.

Modifying to Stage 3:

 Competition cam, Engine balancing, Internal engine upgrades (pistons/head/valves), Adding or upgrading forced induction (turbo/supercharger), Sports gearbox.

Your aim when tuning should be a flat and wide torque band. You want to avoid sending all the power to be at the top end unless you are creating a motor sport car.

As for the Cobalt performance. I would not even consider modifying the car if it's an automatic unless you wanna be blowing through transmissions often. If it's a 5 speed manual though, keep reading. Start with a cat back exhaust, header, and downpipe with high flow cat (ZZPerformance sells all these).

Then do a short throw shift kit (TWM Performance sells these. I have one on my car and love it). I do NOT recommend a "cold air intake" on these cars because it's been dyno proven the intake is not restrictive at all.

The point of our pointers is to give a brief overview of car tuning upgrades and point you in the right direction, our forum is where you can ask for more detailed advice and tips on your car tuning project, the best uprated modifications and all aspects of modding cars.Fast road cams offer one of the biggest torque gains for your money as far as a stand alone tuning parts goes on a NASP engine.

It maximises the intake and exhaust flow and increases the power if done right. Ideally you'd add other mods and finish up with a reflashed ECU. TorqueCars would caution you not to go with a competition cam as this upsets the engines idling and general town driving characteristics.

Comp Cams offers a variety of different camshaft grinds including 3 stages of naturally aspirated grinds, a turbo grind camshaft, and a supercharger grind camshaft.

Don't forget to uprate the fuelling when you are increasing the power - it makes the car more thirsty.

Using high octane fuel is another option if you find you are suffering from detonation or premature ignition on your Chevrolet project after fitting other mods. Uprating the injectors is another beneficial modification and will deliver sufficient fuel.

A fuel pump will only deliver a finite amount of fuel, so you may need to uprate this if your injectors are demanding more fuel.

As for forced induction, it's been done to death on these cars and the limits have been fully explored. The BEST option to start with is supercharging as opposed to turbocharging.

Turbocharging is more complicated, finicky and more expensive to install.

Supercharging on this car meanwhile is ridiculously cheap as the parts to do so can be grabbed off a junked Cobalt SS Supercharged or Saturn Ion Redline, or you can order the parts new from the dealer.

It's a bolt on affair but don't expect the computer to compensate for it. As you have a 2005 2.2L You have 2 options when it comes to the computer. You can either scrap the factory one and go with an aftermarket standalone, or you can do mail order tunes from Trifecta Performance.

The engine internals on the stock 2.2L that you and I both have is rated for up to 250 HP.

Anything above that and expect to switch to forged internals (available from numerous places like diamond, wiseco and JE) or blow up your engine in the process.

Optimal compression ratios depend on which type of forced induction you want. If going supercharged, the optimal compression ratio is around 10:1 to 9.5:1 (much depends on your mapping and fuelling).

The 2.2L comes from the factory with a 10:1 compression ratio so you wouldn't have to do anything until you hit that 250 HP mark.

If you're going turbocharged, it's generally accepted that the optimal compression ratio is around 8.7:1 which will require changing out for forged internals anyways (see how turbocharging costs add up?). Another thing to note is that after installing forced induction, you WILL need to run premium fuel to help try and keep knocking and premature detonation at bay. Both are potentially dangerous and a large reason many people blow their cars up after installing forced induction is they don't change fuels.

Forged internals does NOT include changing the crankshaft, which itself it rated for 500 HP, which I highly doubt you'll be hitting any time soon. If you are interested though, both GM Performance and Eagle offer forged crankshafts rated for over 1000 HP for the 2.2L.

Intake and Exhaust Tuning.

All restriction on these cars is in the exhaust and in the head itself. Having your head ported will do wonders on these engines. If you're doing head-work though, also have a 3 or 5 angle valve job, performance valve springs installed (Ferrea offers these.

GM Performance Parts offers a dual valve spring kit if you can find them, but I personally think that's overkill) and stainless oversized valves (Ferrea again)

If you don't want to pay to have your head ported (and to have your car inoperable during this time), GM Performance parts offers a bolt on head that's already been ported and polished (note this head ONLY works on cars built BEFORE the 2007 model year. In 2007, a cam sensor was added along with a new ignition system and computer).
Here's that part number for the GM PnP'd head: 88958619

Breathing mods are usually next up. Please note that WE DO NOT SEE IMPROVEMENTS WITH INDUCTION KITS, unless you have tuned your car massively and are finding that the standard air intake has become a limitation.

Maximum power gains come from a full induction kit with a cold air feed on heavily tuned engines, this can be sited within an air box but a performance panel filter should suffice for most applications. TorqueCars suggest you use a panel air filter as these are easy to clean and maintain and generally perform better than paper ones.

Sports exhausts can help balance the flow of air through the engine. But if your exhaust pipe is too big, ie: it's over 2.5 inches bore, you will lose much of your flow rate and end up sapping power and torque.

Head work including a polish and port and 3 or 5 angle valve job will really help to release the potential of the engine. In nearly all cases of Cobalt tuning your clutch will start to complain and this needs to be uprated - read our guide on clutches for more information. The best mods in our opinion for your Cobalt are fast road camshaft, remap, induction and exhaust, suspension.

Turbo engines are just begging to be flashed. You will see impressive power gains on most modern turbo engined cars including diesels making a remap one of the most cost effective and impressive modifications for your money.Adding forced induction will see significant power gains but this is usually too expensive to be cost effective. It is usually simpler to bolt on a supercharger than it is to install a turbo. With a turbo the power curve is related exponentially to the engine speed making it harder to map.

Superchargers will give a boost which is correlating to engine speed so is simpler. Adding forced induction will nearly always require a lower compression ratio or water injection.

Alloy wheel upgrades.

Alloy wheels will help the brakes cool down and are usually less heavy than steel ones. Pay attention to your choice of tyres (tires) for your car, a good directional tread pattern tire can really enhance your cars handling. Large Cobalt alloy wheels can decrease performance. If you get big alloy wheels you will be changing your final drive ratio.

Although some people have installed larger rims without problems we would restrict ourselves to a 18 inch rim size as the maximum.

For more information on Tuning your car please join us in our friendly forum where you can discuss Cobalt options in more detail with our Cobalt owners. It would also be worth reading our unbiased Chevrolet tuning articles to get a full grasp of the benefits and drawbacks of each modification.

Problems and issues with the Cobalt

Generally if well looked after and properly serviced there is little to go wrong with the Cobalts.

2005/6 models were recalled for safety reasons to increase the padding in some cabin areas.

Power steering issues led to a major recall in 2010.

A serious ignition switch issue was first documented in 2005 and only finally led to a recall in 2014 of 700,000 Cobalts and Gm were fined for the lacklustre response to this safety issue.

In 2012 a fuel leak issue was discovered and a recall issued, this was apparent in very hot regions where the heat caused cracks in the fuel reservoir.

Please help us improve these tips by sending us your feedback in the comments box below.

We love to hear what our visitors have got up to and which mods work best for them on each model of car. Comments are used to improve the accuracy of these articles which are continually updated. Many of these tips came from our members, see the thread https://www.torquecars.com/forums/threads/improving-performance-on-my-05-cobalt.28829/ for more information.

This article was written by Waynne Smith on TorqueCars, and I appreciate your feedback and suggestions. This entry was filed under Chevrolet. You can leave a response below or join TorqueCars forum to discuss this article and car modification in detail with our members.

If you liked this page please share it with your friends, drop a link to it in your favourite forum or use the bookmarking options to save it to your social media profile.

Check out TorqueCars new YouTube channel, and see their awesome new content...