# Camshaft Questions



## doubleb0924 (Mar 14, 2011)

*Anyone who needs Camshaft information look here first!*

I will be in the market for a camshaft in a month or so for my QSM 2006 A4 GTO. I currently have 34,600 miles on it with the only mod being K&N CAI. I am putting Spintech 2.5" Catback (super pro street mufflers) with an h pipe on hopefully soon. I understand there are many other mods that are needed in preparation for the new Cam and will do a search to find that information because it is everywhere on here but if you would like to make a list for supporting mods on this thread then that would save me some time and would be appreciated. I do not want a monster sized cam and want my car to idle as smoothly as possible. It is a daily driver and because of this I cannot sacrifice reliability, driveability and not a lot of gas mileage. Basically I want to pick up some low end horsepower for my daily driver. Here are the ones that I found that could fit my needs.

ADS4 228/232 115 LSA
TSP 224 R
224/228 114 LSA COMP CAM
222/226 114 LSA

I do know that the lower the LSA the rougher the idle but more horsepower gains. I do not want to go below 114 LSA due tot he fact that I need a driveable car and smooth idle. Can you guys recommend which of the four would be the best for my needs and why? Also I have learned about LSA but do not understand the number 228/232. I know one is intake and other is exhaust timing. But what do these numbers mean for performance and sound? I have read everywhere but still do not understand what these numbers actually mean in "noob" terms. haha Thanks alot


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## RJ_05GTO (Jul 6, 2008)

Im not a camologist but I think most of those cams you listed will gain you close to the same horsepower with minimal difference in idle quality. I dont think a closer LSA really increases horsepower that much, it just changes where the cam makes the power. I think it has a bigger effect on torque though going with a closer LSA. The 228/232 numbers are the degrees of lift or how long the valve is off of the seat. The first number is always the intake and the second number is the exhaust. I have the Texas Speed 224R 114 LSA cam in my car with the stock stall, JBA shorty headers and catted mids. It put down 390rwhp. Idle is great and the car drives almost like stock and sounds great. It would be a great daily driver cam I think. Here is a vid of the dyno run to give you an idea of what it sounds like. I dont have any before cam dyno runs but I would say that it gained around 40rwhp from adding the cam.


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## doubleb0924 (Mar 14, 2011)

Awesome. Thanks for the help. You did not have to change the stock stall converter? I thought this was a must? Also what supporting mods did you have to do in order to keep your engine reliable? Also upon starting do you have any "hiccups" or does it start right away with no sputering? Again thanks!


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## jpalamar (Jul 22, 2008)

You will need valve springs. Probally pushrods. I wouldn't install a cam on an auto without the right stall. You will also need a tune.

Everything else is just extra. Since your an LS2 I would def do a ported intake mani to help flow better with the cam and maybe some headers. This will let you get even more from the cam.


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## doubleb0924 (Mar 14, 2011)

Advice well taken. I think I will do everything you mentioned. Do you have a ballpark price I am looking at for products and installation?


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## BearGFR (Aug 25, 2008)

Here's some basic nomenclature for you:

Duration: how long the valve is open - expressed in crankshaft degrees of rotation (360 would mean the valve is open all the time) Intake is given first, for example: 308/320 would mean the intake is open for 308 degrees of crank rotation and the exhaust is open for 320 degrees of crank rotation. You also have to be careful with these numbers because different cam manufacturers "advertise" duration numbers differently. Some do it at .005" of valve lift, some at .002, etc. Most will also provide duration numbers taken a .050" lift (measured at the lifter, not the valve) as a 'standard' way to compare different cams. Why you care: duration controls how long the valves are open - how long the valves are open affects the rpm where the engine is most efficient (where peak torque occurs). Generally, the "longer" the valves are open, the higher the rpm will be where peak torque occurs.

LSA - Lobe separation angle - number of *camshaft* degrees between peak lift on the exhaust and peak lift on the intake. The effects of LSA in conjunction with duration determine how long the overlap period is (period of time when both valves are open). Cams with "more" overlap also tend to be more efficient at higher rpm, less efficient at lower rpm. Overlap, more than anything else, is responsible for that rough 'rumpity rump' idle that people associate with a hot motor. Again, overlap is determined by the combination of duration and LSA --- a "short" duration cam with a 110 degree LSA might have considerably less overlap than a "long" duration cam with a 118 degree LSA.

Lift - expressed in inches - how much lift is produced by the intake and exhaust lobe - intake is listed first if they're different. Gotta pay attention here too because of differences in manufacturers. Some specify lift at the tappet/lifter, some at the valve. If taken at the valve you also have to consider the rocker arm ratio. I.e. the exact same cam will make more valve lift with 1.65:1 ratio rockers than it will with 1.50:1 rockers. Why you care: Generally, higher lift will allow for more flow capacity, up to a point. Higher lift also puts more stress/strain on everything else in the valve train as rpm goes up. You need stronger springs to keep the lifters from "flying off" the cam, you need stronger rockers/studs to take the pressure from the stronger springs, the physical shape of the cam lobes and lifters can mean that to reach the higher lift you have to start opening the valve "sooner" and keep it open longer (there's a limit to how steep the ramps on the cam lobes can be) - so that can affect duration.

Working with cams can be both complicated and fascinating because of all the interelationships/dependencies that are going on inside the motor. Remember that an eingine is just a big air pump, and every time those valves open and close the air flow through the engine has to start and stop - it's not a continuous flow. Because air (air/fuel) has mass it takes some time for it to start moving and acclerate, but as rpm in the engine goes up there is less and less time available to try to completely fill each cylinder. Think about it and you can see that any given cam will be "optimum" only for a very narrow operating rpm and will be a compromise everywhere else. Fun stuff.

Bear


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## doubleb0924 (Mar 14, 2011)

Bear

This is a great informative repsonse and with examples of how each "process" effects car driveability, sound and performance. I have seen another post like yours but it was not as clear and informative. It is greatly appreciated!


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## doubleb0924 (Mar 14, 2011)

Bear

After reading through the post again I have yet another question.

"Think about it and you can see that any given cam will be "optimum" only for a very narrow operating rpm and will be a compromise everywhere else. Fun stuff."

Does this mean that adding a cam will only better my performance on a certain operating rpm and inhibit a decrease from the stock performance on the rest? For example, it could increase my low range rpm performance but hinder my performance everywhere else or are you saying it will increase my performance in lower range rpm but stay the same in the other ranges, compared to stock? I hope I didn't confuse you. Thanks again


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## svede1212 (Nov 1, 2005)

Altho the info here is good you really should ask a cam expert which cam would accomplish your goals. Ed Curtis over at FlowTech Inductions is one of the best in the biz with the LS motor and can recommend and grind a cam to meet them. He sells complete kits so the only things else you should get is a set of headers, a really good tuner and a higher stall torque converter. You could skip the converter is you went for a really mild cam but frankly the cost of doing this would be a waste with a really mild one and I guarantee you'll wish you'd gone bigger.

A decent cam will make power everywhere with the biggest gains being where the grind "tuned" for. A low lsa cam with medium-high duration will make a low of power with it kicking in lower in the RPM range like you use on the street. Moving the power band up is usually reserved for drag racers that rev the engine up very high. My StreetSweeper HT kit is a 228/232 .612/.600 111 lsa that added about 70 HP above what the headers gained and works on the street really well. The power band runs from about 2,500 RPM up to 6,400. The kit came with cam, seats, seals, retainers, springs, locks and hardened push rods. The cam idles only 25 RPM over stock. I can not stress enough that the tuner will make or break having a happy cam owner.


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## doubleb0924 (Mar 14, 2011)

Svede

Thanks again for yet another informative post. It seems the one thing that you stress isfinding a good tuner. That is one thing that is on the top of my list. With your LSA being 111 do you have a "sputtering" idle and issues starting your car or can these symptoms be "tuned" out. Also what Cam do you consider really mild? Were the ones listed in my beginning post too mild and not worth the money?


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## BearGFR (Aug 25, 2008)

doubleb0924 said:


> Bear
> 
> After reading through the post again I have yet another question.
> 
> ...


You are wise beyond your years, Grasshopper 

Yes, that's exactly what it means. If you think about it, it makes sense. The twisting force (torque) that an engine produces comes from the fuel it burns - the more fuel you can burn efficiently, the more torque you get. Given that there is a specific ratio of air/fuel you need in order to release all the energy from the fuel through burning, the limiting factor of how much torque an engine can make becomes directly related to how much air/fuel you can cram into it. For normally aspirated engines, the only force available to you to do that is that provided by atmospheric pressure working to fill cylinders due to the partial vacuum created by the motion of the pistons. Cubic inch displacement is king. More inches = more volume = more air/fuel = more max torque. It really is that simple. Notice I didn't say anything about horsepower or rpm yet. Peak torque is related to "air capacity" of the pump (engine) and has nothing to do with rpm - yet. Remember I said that air flow has to stop/start all the time? Any given camshaft profile by its nature is going to "allow" the cylinders to fill their lungs completely (or nearly so) only at a narrow rpm range. That's called volumetric efficiency, and whereever it's highest, that's the rpm where the motor is going to produce it's torque peak. Changing the camshaft profile is going to move that peak up or down in the rpm range, but the size of the peak isn't going to change much if at all. Take an engine that makes 500 lb ft of torque, max, at say 2400 rpm and put a longer duration cam in it, it's still going to make "only" about 500 lb ft max but it'll be at a higher rpm - say 3400 rpm. Put another way, changing the cam changes the point of peak VE (volumetric efficiency) but it doesn't give the motor bigger lungs. Now we can talk about horsepower. Power (horsepower) is a measurement of the rate that work is being done. The 'work' in this case is torque. Horsepower is a calculated number - it can't be directly measured. The formula is (torque X RPM)/5252.
Now you know why changing to a rowdier cam causes a motor to "make" more horsepower. By moving the torque peak to a higher rpm - when you plug the torque into the horsepower formula the result is larger - because of the higher rpm - the motor is now doing work (torque) 'faster' (higher rpm) than it was before. Viola - more horsepower.

As you have surmised, moving peak VE up in the rpm range has a negative effect. VE at lower rpm is worse. Torque (and as a result horsepower) at lower rpm are going to be less than before. It happens because the valves are now open "too much/too long" for the motor to be efficient at low rpm. The problem is called "reversion" and is mostly due to the overlap period when both valves are open. You 'need' that period at higher rpm so the motor can get its lungs full, but at lower rpm the valves are open SO long that the air flow can stop and change directions, allowing the motor to suck burned exhaust back in through that still open exhaust valve, polluting the intake charge, and forcing some of that nice fresh air/fuel back out through the still open intake valve. That's where that 'rumpity-rump' rough idle comes from --- not because the motor's making a ton of power but quite the contrary - it's so inefficient at low rpm that it's barely able to run at all.

All of the above is why it's important to choose a cam based on the total package, how you're going to drive the car, transmission, gear ratio - etc. Everything has to work together as an integrated system for best results.

In 1969 when Pontiac introduced the 400 Ram Air IV, it had one of the rowdiest cams they ever put in a production car. The Ram Air IV wasn't available with a/c, and the "smallest" rear gear ratio you could get was 3.90:1 - both for good reason.

If your head isn't mush yet, there's one more topic I left out of my previous post about cams and nomenclature. All the stuff in that post had to do with characteristics of the cam shaft itself. There's one more measurement that's important and that's the "Intake Centerline" - ICL. That's what determines the relative timing of when the intake valve reaches peak lift with respect to the crank on the intake stroke. Cam manufacturers will recommend with each cam a specific ICL for how the cam is to be installed, in crankshaft degrees after top dead center (ATDC) where peak intake lift occurs. There are different means of "adjusting" the ICL during cam installation such as using offset keys on the crank and/or cam gears, timing sets with multiple keyways for different settings, etc. You might have heard the term "degreeing a cam" - that's the process of installing a cam and "placing" the ICL where you want it to be in relationship to intake TDC. Installing a cam right where the manufacturer recommends is called installing it "straight up", installing it so that the intake peaks a (very) small number of degrees later than recommended is called "retarding" the cam, installing it so it peaks earlier is call "advancing" the cam. Retarding means the intake valve will open later and will close later, and will tend to move the torgue peak (peak VE) higher in the rpm range and will also tend to lower peak cylinder pressure, advancing has the opposite effect.

Fun stuff. :cheers

Bear


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## doubleb0924 (Mar 14, 2011)

Bear

Impressive. I learned a lot through your post. Now it seems like I do not even want an aftermarket cam shaft. I also keep forgetting that the camshaft that i have in my car already is doing the same as an aftermarket one, correct. The stock cam is displacing the VE somewhere and lacking in the opposite "direction" either low or high rpm. So choosing an aftermarket Cam is basically based on what the user wants more of, either low end "HP" or mid to high range "HP". I will be honest to everyone here, I have no intentions of taking my car to the track and running 1/4 miles. My goal is to keep my GTO reliable, daily driver but to make it fast enough to be competitive on the streets. I may also be interested in advancing my ICL instead of retarding in order to get my smooth idle. 
Thanks again!


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## BearGFR (Aug 25, 2008)

If this stuff interests you, there's a way to experiment without having to sink a ton of money and time into parts. When I was getting ready to build the engine for my 69 GTO I licesned a copy of Performance Trends Engine Analyzer (plus) software. (Google it). It's a modeling package that lets you simulate the effects of various ideas. Like any program, it's only as good as the input you give it - if you lie to it and give it overly optimistic information, then it's going to lie right back to you with inflated predictions.

It's an easy way to "play" with different cams and how they're installed to see what the relative effects might be.

I found that when I gave it accurate information it predicted very closely what my engine actually ran on the dyno when I broke it in.

Bear


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## doubleb0924 (Mar 14, 2011)

I will have to look into that. I would like to see how different setups run and all before I go ahead and make that purchase.


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## svede1212 (Nov 1, 2005)

You'll produce more torque and HP with an aftermarket cam all the way down to pretty low RPM compared to a stock cam and get a larger VE. You don't give up power anywhere outside of idle where it doesn't matter. The cam selection will bias how that extra power is distributed but it will make more power everywhere. My LS1 makes over 300 ft/lb of RW torque from 2,500 RPM and up. 300 RWTQ is what it used to make only at PEAK torque and it now peaks at 390 ft/lb. The extra lift and duration play a large role in that. EPA considerations are the biggest driving force in modern muscle cars from the factory. Also comparing old school "big" cams (which would be small today) is fruitless. The tuning ability of ECM fuel injected engines is so vastly superior that drive-ability isn't sacrificed unless you 1. go crazy or 2. don't find that good tuner. The 224r is a pretty nice cam if you don't want to go bigger. The 228-230 range is a little nicer. You'll notice a big difference compared to playing around with the stock one. These LSx engines really respond to the right parts and good tuning for them. They go from roughly one horse per cube up near 1½ per cube really easily. I still say correspond with a cam grinder. They know what works for you better than we internet experts.


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## svede1212 (Nov 1, 2005)

Oh and I also wouldn't waste money on an analyzer when you can get a true tuning suite/logging system like HP Tuners or EFILive. With a little bit of reading and a modicum of intelligence you can tune your car as well as 90% of tuners out there and have fun doing it.


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## RJ_05GTO (Jul 6, 2008)

Dont over think this too much man. You want more power? A cam is a good way of getting it. You will make more power all the way through the curve. You will not lose anything. A stall is not totally nessassary with a small cam like a 224 duration with this engine.


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## RJ_05GTO (Jul 6, 2008)

doubleb0924 said:


> Awesome. Thanks for the help. You did not have to change the stock stall converter? I thought this was a must? Also what supporting mods did you have to do in order to keep your engine reliable? Also upon starting do you have any "hiccups" or does it start right away with no sputering? Again thanks!


A stall isnt really needed with the 224 cam I have. I plan on getting one soon. The other parts that are typically needed when changing the cam is hardened pushrods, you have to measure for proper length because the base circle of the new cam will be smaller. I ended up using the 7.425'' rods. You will also need new valve springs, gasket kit, balancer bolt, and if you are doing it yourself a spring compressor tool, spark plug adapter air fitting, air compressor, small 3 jaw puller, torque wrench, balancer install tool, flywheel locking tool and decently equipped tool box. I used assembly lube instead of oil cause it just made me happier. The car fired right up after the cam change just like I never touched the engine. After the idle settled down it started idling kinda rough. I bumped it up 100rpm with my predator tuner and it ran fine after that. I drove it to get the tune and all is well.


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## doubleb0924 (Mar 14, 2011)

Svede:

The difference between the 224R or 224/228 Cam and the 228/232 is that the valves stay open longer, correct? If I am correct, does this also mean that the MPG is worse as well? I know LSA plays a role in idle functionality but does the intake/exhaust valve number effect this as well? I know a great tuner will be able to accomodate this but I would like to have my setup as close as I can get it to my needs, jus tin case the tuner I choose does suck. I will also take your advice and contact a custom cam grinder. Thanks for your input.



RJ:
Did you see great gains with your 224 cam? What is your LSA and did you go for more low end or high end torque?


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## BearGFR (Aug 25, 2008)

doubleb0924 said:


> Svede:
> 
> The difference between the 224R or 224/228 Cam and the 228/232 is that the valves stay open longer, correct? If I am correct, does this also mean that the MPG is worse as well?


Probably, but "it depends" on what normal is for how you drive. That longer duration is going to make the motor more efficient at a higher rpm at the expense of being less efficient at lower rpm. If you spend most of your time running at an rpm that's less than the cam's "sweet spot" then mileage is going to be worse than it would be with a shorter duration cam.



> I know LSA plays a role in idle functionality but does the intake/exhaust valve number effect this as well?


It does. LSA and duration together affect the overlap period, and it's the overlap period that has the biggest single effect on idle quality.



> I know a great tuner will be able to accomodate this but I would like to have my setup as close as I can get it to my needs, jus tin case the tuner I choose does suck. I will also take your advice and contact a custom cam grinder. Thanks for your input.


Don't give a tuner too much credit. All they really do is tailor the engine's fuel delivery curve and ignition advance curve so that they're optimum for either performance (just a tiny bit on the rich side) or ecomony (just a tiny bit on the lean side) for the motor across the entire rpm range. There's only so much they can do. The best tuner in the world is not going to be able to make a long duration, tight lsa cam with lots of overlap that's optimized for high rpm power idle like a stocker - it just ain't gonna happen. With a really nasty cam, at idle the motor's going to be sucking half the exhaust back into the cylinder through the exhaust valve and blowing half the fresh intake charge back out through the intake valve during the overlap period and that's not something you're going to fix with fuel mixture or ignition timing. 

Bear


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## doubleb0924 (Mar 14, 2011)

Bear

Thank you again for yet another helpful response. It seems as if a shorter duration is what I will be leaning towards. Very seldom do I drive in high rpms. I just need to keep researching to find out the right combination of duration and LSA I need for my particular situation.


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## ViperT4 (Jul 18, 2010)

I'll jump onboard here because I'm also looking at a cam with nearly the same cam specs when i get to do one in the summer. I want to do the TSP 228R. Is there really that much difference in duration between a 224 and 228? OP, I think to really see any significant savings due to duration you'd have to back down to the 220R. Same lift but smaller duration. That means there would be left overlap at a given LSA, and you could have a lower LSA to bring the power curve down but still smooth idle. 

But I think going that small almost makes having a cam not worth it, and there are tons of people on the internetz driving around 228R and 224R cams with like-stock off idle driveability.


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## doubleb0924 (Mar 14, 2011)

Viper

I definitely agree, going to a 220R would defeat the purpose of buying a Cam. I also am leaning towards the 224R, 224/228 or even the 228/232. All in which I think an LSA of 114 will be suffice. What LSA are you looking into?


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## doubleb0924 (Mar 14, 2011)

*Duration differences??*

Yet another question. What if the intake and exhaust duration are more spread out, what effects does it have on performance or idling ability? Lets say the difference between a 224/224 and a 224/230 (just as an example).


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## ViperT4 (Jul 18, 2010)

When you open up the exhaust duration more than the intake it will help to clear out all of the exhaust gasses better. I'm not sure what that does for power but you'll be cleaner so it helps it Commi states like Cali that have strict smog laws.

I will probably just go for the 112. I want the powerband as low as possible and I really don't care about the gas mileage even though it is my daily. If i did I'd have gotten a diesel Golf or some sh*t. My only requirements for picking a cam are are a LSA >111 and to stay under .600" lift and any cam with lift under .600" looks like they stop making use of longer duration at around 230-232 (there's also a general relation between lift and duration due to some standard lobe profiles- the larger the lift naturally the more the valve will be open past .005"). So to give my springs some safety tolerance I'm going with the 228R probably- 228 duration and .588 lift intake and exhaust. Should make a safe extra 50 hp at the wheels. Could I split hairs and worry about 2* here and .002 there? Yeah probably. Will I really feel a difference driving it? Probably not. That's not to take away from the people who work on this as a day job, I'm fascinated by what some people can do with a cam. I agree you should talk to a cam expert about what the general specs you need to be looking at to meet your goals are. But once you do that I'd be hard pressed to say there's a cam you won't like more than your stock one.


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## RJ_05GTO (Jul 6, 2008)

doubleb0924 said:


> Svede:
> 
> The difference between the 224R or 224/228 Cam and the 228/232 is that the valves stay open longer, correct? If I am correct, does this also mean that the MPG is worse as well? I know LSA plays a role in idle functionality but does the intake/exhaust valve number effect this as well? I know a great tuner will be able to accomodate this but I would like to have my setup as close as I can get it to my needs, jus tin case the tuner I choose does suck. I will also take your advice and contact a custom cam grinder. Thanks for your input.
> 
> ...


The car put down 390rwhp on the dyno. 114 LSA. It feels like it has more power everywhere. I dont have any before runs but Im pretty sure with the boltons I have before the cam the car was around 350ish rwhp. So im guessing around 40rwhp from the cam. I ran 12.90's before the cam with nitto 555r's. Im going back to the track either on the 4th or the 11th. I will post up my new times in a new thread. I can tell the car is faster than it was. I dont know how accurate it is but I used my dashawk for reference before I was hitting 4.3 sec 0-60's with the drag radials on the street and thats stabbing the gas all the way to the floor immediately with little or no wheel spin with the dr's. I am now hitting 3.9x seconds with drag radials and I still have the stock torque converter. I do my runs on the same road in the same spot for the best accuracy possible.


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## BearGFR (Aug 25, 2008)

Longer exhaust duration does give the exhaust valve more time to do its work. Question is, does it need it? Depends on the rest of the engine's "respiratory system" and how well it works. Things such as chamber design, exhaust ports in the heads, exhaust system dynamics, etc. all play a role. Can it work "too well"? Sure --- "too well" in this case means that you start blowing part of your intake charge right out the exhaust along with the burnt stuff. As long as you don't get into reversion that's not going to hurt you on performance, but you're going to feel it in your back pocket in terms of fuel economy (or the lack thereof).

If you're wanting drivability and a nice smooth idle ---- tell me again why you're wanting to change away from the factory cam? Contrary to popular belief the factory engineers aren't idiots. Their life-blood day in and day out is dealing with the inherent compromises that have to be made to meet goals in the areas of economy, emissions, and performance. Deviating from that to emphasize one of the three is pretty much guarateed to degrade one if not both of the other two.

Bear


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## svede1212 (Nov 1, 2005)

A tuner will make or break having a cam. Tuning WOT performance is fairly easy. Low RPM "normal" driving, cold start and idle are where the nuances are. You don't lose much if any MPG with a reasonable cam. Even after a fairly healthy cam (228/232 .612/.600 111), heads and other upgrades like 3.91 gears I still get 25 highway (I do my own tuning).


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## doubleb0924 (Mar 14, 2011)

Great point about why I am looking for a change from the stock camshaft. I want to make my car as powerful as possible, I just do not want to do so with daily consequences. Daily consequences such as having to restart my car over and over because my vehicle keeps stalling, getting 16 mpg when I was getting 21 and difficulty in traffic. I feel that an aftermarket cam will provide better performance than my stock as long as I do not go too mild with it. I feel any aftermarket camshaft will be better performance wise than my stock camshaft. I am not looking to get a huge hp/torque gain from this but I would like to get as much as I can without being uncomfortable driving it everyday. I guess I am looking to get my cam setup like Svede has his, very reliable, good power gain and get good mpg (25 would be great but not expected).


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