I have been reading all the post both here and on cobalss.net about changing the pulley on the S/C.
So far this is what I have figured out:
1. There is a solenoid that only allows the S/C to make 12 or so PSI.
2. Adding a pulley causes more heat. (is this heat just underhood temps, or is it the temp of the motor that needs to be adressed by a new thermostat or cooling system upgrades).
3. In order to fully benefit from a new pulley, one needs to get an intake, header, exhaust first.
4. There is POSSIBLY another way that the PCM controls the boost that the S/C put out. <---- I am not quite sure about this but it seams that everyone agrees!
What i havent figured out......
1. How much boost can the S/C effeciently make? (MAX PSI)
2. How much boost can be made before engine internals need to be strengthened.
3. The WHOLE heat issue really throws me for a loop!!!!!!!!

If there is any ABSOLUTE FACTS i am missing...please fill in. If any one has DEFINITE answers to these questions....please let me know. I know I am not and engineer and dont know a whole lot about F/I engines. I want to change my pulley b/c there is no doubt that this gives more power, i just want to do it right the first time without FUC$#@! my engine!!!! Thanks for any help pn clearing up these issues. :confused: :confused: :confused:

The questions you are asking here are all good ones, and to be perfectly honest, 99% of the people here (myself included) do not fully understand the workings of a supercharged engine like this. I will try to explain the basics as best I can. If someone else with a degree & experience with mech engineerings wants to chime in, by all means...

So, to start from scratch: A smaller pulley drives the SC faster. Faster = more air pushed = more horsepower, right? Not really. The supercharger has an optimal operating range, and if you drive it outside that range (ie too fast), then it will NOT flow any more air. All it will do is heat the air up more.

This is the heat we're talking about. It's the temperature of the air being pushed into the engine (called the intake charge). A supercharger dramatically increases the temperature of the intake charge. This causes higher temperatures inside the engine, which is very bad, because if the temperatures get too hot, you start to experience a condition known as knock, detonation, or "pinging". Essentially, knock is when the charge is so hot that the fuel ignites on its own (ie, not ignited by the spark plug), and burns very rapidly and in an uncontrolled manner. It's called pinging because the intense pressures that build up actually cause the surface of the piston to distort, which makes a metallic "pinging" sound. That's the sound of a hole about to be blown in your piston.

The engine computer can detect knocking when it starts to occur, and it will retard the ignition spark to compensate. Retarding the spark lowers the combustion pressures, which protects the engine from damage. It also reduces performance. Significantly. So in other words, if you take the same engine, same supercharger & boost, and heat up the air being pushed into the engine, all you will do is hurt performance. This is the danger of smaller pulleys. There's a fine balance between a smaller pulley that moves more air and therefore makes more power, and one that puts the supercharger outside its efficiency zone, and just makes excess heat.

Now, to try to answer your questions:

Intakes and exhausts both relieve restrictions. Less restriction = less resistance to flow = less heat. Basically, you're allowing the engine to breate easier, which lessens pumping losses and heat. You don't have to have a header to get a smaller pulley, but you will almost certainly get better performance if you do. It's like trying to blow really hard through a tiny straw. Not easy.

Here's the problem with talking about max boost: Boost is pressure. Pressure is a measure of restriction. That's a bad thing. If you're registering 12PSI, that means the supercharger is pushing really hard, so hard that 12psi of pressure has built up, but the engine can't inhale anymore!! What I'm trying to say here is that to assume more boost = better is not true. What you want is more airflow. Here's a really good link that explains it in more detail; I'll save myself from retyping it: http://gcoast.com/turbo/technical.html

I have not actually taken the time to sit down and calculate it out. In general, however, it appears that the M62 used in this motor is fairly close to its efficiency ceiling. In other words, it may not be able to flow a lot more air before it starts to drop off. This needs more investigation; hopefully all the companies getting involved can shed some light.

As to the engine internals, it's more about safety than absolute power. I would be willing to bet that the internals can hold down 400+hp if it's done safely! My point here is that, again, you can't say that it'll handle X psi of boost. It depends on the power level, and the state/tune of the engine. There will be some hack who puts on a smaller pulley, disables his knock sensor, and shreds a piston while pushing only 13psi and 220hp. Conversely, there will be someone who, with a proper tune, can pull off 400hp without really hurting the motor.

Hope this helps some. If I confused you any more on some points, feel free to ask. :)

Edit: as to swapping your pulley, the best advice I can give you is this; unless you're an engineer or mechanic or have experience with this stuff, do not be the first one to do it. :) Let performance shops or other 'pioneers' experiement first, and benefit from their learnings. PSI-FI is supposed to have a kit out shortly, they no doubt have some experience, but they seem to be being rather tight-lipped about it. Others will come along as well. Your best bet is to keep watching these forums, and in 3-4 months, you'll probably be able to get much clearer answers about the specifics of this motor, which is what's really important. Going and buying a pulley right now without experience with the LSJ is a pretty risky and not terribly intelligent move, IMO. :)

thnks, that definetly sheeded some light in dark areas. (espicially the more boost = more power) <-----i hear everyone talking and they are always bragging on how much boost the have, but it not neccesarily true they are making more power. So now what i think i will do is just wait a while till some companies just deliver a complete package i.e. pulley, tune, plugs, etc. and for right now I will get a header, DP, exhaust, and intake b/c without a doubt this will yeild power increases without damaging the motor. Thanks for all your help and sorry you had to type so much.

One more thing.....doest the cobalt ss have an intercooler? If so where is it?

No prob man. :)

If the only thing you take away from all that is that more boost does not equal more power, then, frankly, you're ahead of most people. Most people just say stupid stuff like "my RSX is running 45psi, I r0x0rz!". Ugh. :mad: Best example is this; consider your stock SS. It makes 205hp, and pushes about 12psi boost. If you took your car, did nothing else, but swapped the cylinder head for a better one (more free flowing, bigger valves), you would notice that the boost would actually DROP. Say to 10psi. Yet a dyno would show you to be making more than 205hp. In other words, 10psi+freer flowing made more power than 12psi. This is a perfect example of why you can't use boost to measure power.

Good call on the header and intake. On a supercharged engine, any kind of mod that improves breathing is usually beneficial. And it will only be more beneficial if you do go to a smaller pulley at some point.

alright, so i understand that a smaller pulley dosent always mean more power if you dont have the componets to support it. So adding up boost numbers at the manifold dosent turn into power unless the openings for the air to flow thru are there. My other question is does the SS have an Intercooler? and if it does where is it at? If it doesnt, wouldnt it benefit greatly from having one?

Yep, that's exactly right. The SS does have an intercooler, however it's sort of cast into the intake manifold. Ie, it's all one piece, and from what people who have been into the engine thus far are saying, it looks like it's going to be very difficult to upgrade it. :( Which is too bad, because, yes, an upgraded intercooler with more capacity to cool the intake charge would help significantly.

(the supercharged 3800 GM uses in Grand Prix GTPs, for example, doesn't come with an intercooler. It only makes about 7psi stock. GTP owners have found that if you add an intercooler to cool the charge down, you can run a much smaller pulley and make a lot more power. Pretty good for the price of a $500 intercooler. Unfortunately because of the way the LSJ is designed, it doesn't look like intercooler upgrades are going to be that easy for us. :( )

Very well understood!!! Guess it is one of things that only time will tell. Thanks for chat, you seem to be up to snuff on the basics and some of the advanced stuff. I really appreciate how you only gave FACTS unlike some people who give their opinions and what they think should go on. Once again thanks and if i need ya again i will shoot ya a private message or something.

Yep, that's exactly right. The SS does have an intercooler, however it's sort of cast into the intake manifold. Ie, it's all one piece, and from what people who have been into the engine thus far are saying, it looks like it's going to be very difficult to upgrade it. :( Which is too bad, because, yes, an upgraded intercooler with more capacity to cool the intake charge would help significantly.

(the supercharged 3800 GM uses in Grand Prix GTPs, for example, doesn't come with an intercooler. It only makes about 7psi stock. GTP owners have found that if you add an intercooler to cool the charge down, you can run a much smaller pulley and make a lot more power. Pretty good for the price of a $500 intercooler. Unfortunately because of the way the LSJ is designed, it doesn't look like intercooler upgrades are going to be that easy for us. :( )

Dan, you are correct on Intercooling is the best way to increase boost and performance on any Pontiac GTP / L67 Supercharged Engine, but there is other ways of improving the performance and of course run higher levels of boost, like my 97 GTP that has been doing since day one I bought it. To my 97 Pontiac GTP does produce 12 lbs. of boost on the street, without an Intercoooler and and "0" on any Knock Retard at all.

Also for a good Intercooler System for any GTP will run you approximately $1000 to $1500 , depending on it's volumetric efficiency of not only the Intercooler core itself, but also the Heat Exchanger the kit comes with.

As for the 2.0 SC Engine in the Cobalt SS as well as the Ion Redline vehicles , you will no doubt see someone come out with a more efficient Heat Exhanger kit for it , just like we have for the Pontiac GTP's, Ford Cobra's, Lightning/Harley Supercharged Engines.

Thermal properties are very important to any and all Forced Air Induction Engines and the necessary precautionary measures need to be addressed , before trying to build more supercharger boost over the stock factory configuration, as many of us supercharger owners have done exactly that, even without the use of an Intercooler unit installed upon our L67 SC engines.

Hope this helps

Ronnie,

No prob dude. :D

Terry,

Of course. I didn't say the only way to improve performance was to add an intercooler. I said it was a good way. :)

And yes, perhaps I should have been more specific. No doubt someone will come out with a better heat exchanger for the LSJ. It's the intercooler core that will be difficult to upgrade. (Note, before we start quibbling over semantics again, that I said difficult, not impossible. :D No doubt someone will come out with a way to upgrade the core too, although it may turn out that it necessitates replacement of the entire intake manifold, making it costly...)

Actually, the intercooler core is mounted between the radiator and A/C condensor. Just follow the routing from the IC Pump to the surge tank up top. It would be quite difficult to upgrade as you would need to change the mounts. It sounds like you are referring to the Laminova tubes, which sit up top near the intake manifold. The actual core is what sits down below.

Alright, now we're quibbling semantics again. Technically you can call either one the 'heat exchanger' because they're both heat exchangers.

The laminova tubes inside the manifold will be difficult to swap/upgrade. The heat exchanger on the front, by the radiator, will be less difficult. All you need is to fab up some appropriate mounts.

I am glad I have a naturally aspirated LS1 also........ Maybe i will just stick to modding it :confused: :confused: :confused:

Or you could sell it to me and I'll stick w/ the LS1!! LOL

Or you could sell it to me and I'll stick w/ the LS1!! LOL


LOL me personaly i would take the LS1.

Yeah me too, IF there was one reasonably priced ANYWHERE!!!

I have seen a few LT1's but no LS1's but a LT1 might be a option just to bet around LOL.

Nah Im not big on the LT1's Plus the front ends of those Camaro's dont look as good

Well i like all of the Camaro's except the 1970's to 1981. I did not like the head lights.

Oh dont get me wrong I LOVE ALL CAMARO's!!! Just prefer the 98+ headlights to the what is it 93 or 94? to 97 year's headlights. AND the LS1 is more powerful AND has more potential!!!

Oh dont get me wrong I LOVE ALL CAMARO's!!! Just prefer the 98+ headlights to the what is it 93 or 94? to 97 year's headlights. AND the LS1 is more powerful AND has more potential!!!


Yeah true but cant argue with a $6,000 price tag on a Z28 just to bet around untill I can get my SS.

Yeah true but cant argue with a $6,000 price tag on a Z28 just to bet around untill I can get my SS.
Oh are you lookin at one??? $6000 really isnt too bad a price, what is the condition? mileage? tranny? and if manual, then clutch?

Oh are you lookin at one??? $6000 really isnt too bad a price, what is the condition? mileage? tranny? and if manual, then clutch?


Kind of my Camaro is given me alot of problems that are bothering me. Good condition like 65,000 mile i think and it is a auto but i dont care it is a good price and i would do a Dual Gate shifter kit on it.

I'll part my 98 Z for 8000 with the nitrous still in it. 95 almost 96 thousand automatic with 2.73 gears. Went 12.68 @ 112 with a 100 shot.

6 grand for an LT1 Camaro is reasonable if it is very nice. Buddy of mine just picked up a '96 automatic, convertible with 70M miles for 7 grand last week. Very clean, needed a set of wires, other than that it looks/runs perfectly.

Yeah but a 98 is an LS1 (not an LT1), LS1's have much more potential, better overall engines!!

Yeah but a 98 is an LS1 (not an LT1), LS1's have much more potential, better overall engines!!

The car he was talking about is an LT1

I have seen a few LT1's but no LS1's but a LT1 might be a option just to bet around LOL.

and

Yeah true but cant argue with a $6,000 price tag on a Z28 just to bet around untill I can get my SS.

To tell the truth, I would go ahead an pony up the extra cash and get an LT1 'Vette over an F-body of similar vintage. Insurance is so much cheaper that the extra cost of the car is offset after a couple of years.

Same thing with the LS1 cars, spend the extra cash to get the Corvette. (if you can swing it, of course.)

LOL Open mouth insert foot!!! :D

I thought you were talkin about SSprayedSS's Camaro, sorry!!

Its been so long since me and 87 had that conversation, I forgot all about it!
Oops!! :o

LOL i know it was such a long time ago.

Holy off topic batman. I think the mods should clean this post up a bit so this poor dude doesnt have to read through BS to find an answer to his questions.

Ok, correct me if I am wrong here. The intercooler is actually inside the intake manifold. It is a air to water intercooler which means it is some sort of metal material with water running through that to transfer the heat to the water. The part on the front near the radiator is where the water returns to and is cooled then recirculates back through the intercooler again with cooler water to start the process all over again. It would need a seperate 'radiator' in order to cool the water down outside of the engine or else it would be using the same hot water over and over which would be just like not even using an intercooler at all. So this is why the intercooler is two parts rather than one like the traditional air to air intercooler.

Yes the intercooler core is inside the intake manifold. Whats in the front bumper is the heat exchanger for the IC coolant, not the core as someone else stated. The IC core is always the object the air passes through to be cooled, whether it be air to air, air to liquid, or liquid to air. If it was an air to air, the core would be where the heat exchanger is. But you cant really have the core in the bumper in a roots blower setup, unless you had some stupid setup where the blower output went into a manifold, through charge piping and through the IC, and then back to the TB. Yeah it could be done but the logistics and engineering behind it would just be backassward lol.
Whats on the SS is basically the same as whats on the Cobra and what you can buy for GTP's, which is an air to liquid.
The other type of liquid IC you can have is the liquid to air, where the IC is actually sealed in a tank surrounded by cooled liquid, and the liquid in the tank is pumped through a similiar system as the air to liquid IC setup, with a heat exchanger in the bumper cooling the liquid. This is the setup that is found on the GMC Syclone and Typhoon, and what you see being used in alot of turbo race cars, as well as in some centrifugal supercharged setups.

I think I've seen the word liquid enough in the post alone that its lost its meaning lol.