Modifying for " Dummies"

[nvpliers]

Unbelievable. I'll make it clear to them not to mess with the tune. But that's no guarantee I know. Maybe I'll just let the performance service guys [non-GM] perform the service stuff I can't handle.

[Raven02TA]

Originally Posted by Dr Jekel

Thanks,

Raven, This is an awesome write up and you seem to have alot of knowledge about this.

I have a few questions on your post. In a couple of sections you indicate that GM's original parts are really not that good and don't hold up to even stock numbers, like tranny , rear etc..... Why is this? Why would they do that and still warranty for 100000 miles?

When modifying, mine for example I am adding a cam, updated valvetrain, headers, highflow cats, cai and of course a tune, what is to be expected in reliablity, Camshaft Specs are: 227/239 .614/.624, supposedly a good street cam with moderate lope for the old muscle car sound.

Since you are in the know so to speak. All that HP does not seem good especially when you cant put it to the pavement and when you do it breaks stuff. At C5F I believe I saw more tires spinning than anything.

So for the guy like me who wants a little added power, mostly a sound upgrade for the lope, not going to race, maybe dust a few ricers off the redlight, or maybe some hot laps at the Talladega Superspeedway on open days, just to see what it will really do. What do you recommend?

when we originially did the write it i was speaking in trms more towards the 4L60E trans and the and the Twig they called the GM 10 bolt rear end. neither could hold power very much. and back then they only had a 3 yr 36K mile warrenty. I havent updated that write up in 6 years. but in principle for most in it still applies.

To be honest. whether its for getting on it from time to time. or going to the track weekly, the first thing i always recommend is doing your suspension/gears (or a built rear) and some drag radials.... there is no point in have 380+ hp. without being able to put it to the ground. You guys are especially hurting for that with those big wheels and low profile tires. but of course. what comes with traction is breakage. thats where the comment of "GM's original parts are really not that good and don't hold up to even stock numbers" applies.

I learned the hard way. I did my motor first back in the day. Heads/cam. Made 435 rwhp only ran 12.6's because i couldnt hook. when i did suspension and tires. i hooked..... and broke lots of rear ends and severals transmissions after i put in a 9" rear. It comes with the territory of learning the limits of the cars.

but for someone like who who doesnt plan to race or just occasionally get on it. im sure you could get away with doing the cam first then move to your suspension.

[Dr Jkel]

Is there a difference in take off power and rolling power. Reason I ask is sometimes when cruising, I notice I can not suck up people like I thought I should, I guess from 35 to 65, you know these people they pull up beside you and want to race. I have tried not tried from a dead stop, guess worried about the tailshaft on the tranny breaking. Just was kind of curious, wouldn't want to embarrass myself, lol. I usually just let them go especially when the boys 11 and 13 are riding with me.

But like I stated earlier my mods are mostly for the sound and the added HP is just a bonus. I think I relayed that to the vendor I bought my stuff from enough that he knows what I want.

I did ask about the heads to see if they needed any work while doing this and was told that basically with the mods I am doing that these heads flowed well and basically would be wasting money porting, polishing etc...

I am sure GM did not squeeze every bit of power out of these motors coming from the factory, and that they are tuned for more reliability and dependabilty rather than performance and I am sure that the man doing the tune on my mods understands what I am going to do with it and will tune it more towards the middle than pushing the limits.

I guess it's like they say "How fast can you AFFORD to go?"

[Raven02TA]

Originally Posted by Dr Jekel

Is there a difference in take off power and rolling power. Reason I ask is sometimes when cruising, I notice I can not suck up people like I thought I should, I guess from 35 to 65, you know these people they pull up beside you and want to race. I have tried not tried from a dead stop, guess worried about the tailshaft on the tranny breaking.

as long as when you do this the clutch is already engaged you will be fine. (foot off the pedal, while in gear and already waiting at a desired RPM) unlike some people who like to push the clutch in and rev it to 6K and dump it @ 35 mph.

reason being. when the clutch is engaged and its in the gear you want already, everything is already set in motion. when dumping the clutch all the parts are loose. so when you dump it. it smacks everything around resulting in immediate or eventual breakage (depends on mods, traction, driver)

[Dr Jkel]

so I take it that I should be around 3k in a gear then mash it or should i be higher rpm'd

[Darth_Emma]

Originally Posted by Dr Jekel

I guess it's like they say "How fast can you AFFORD to go?"

The one I've heard a lot is, "You gotta pay to play." I think that applies not only to mods to gain HP, but also repairs from pushing things past the edge.

[Raven02TA]

Originally Posted by Dr Jekel

so I take it that I should be around 3k in a gear then mash it or should i be higher rpm'd

thats about right, anywhere between 3-35K is fine.

Originally Posted by Darth_Emma

The one I've heard a lot is, "You gotta pay to play." I think that applies not only to mods to gain HP, but also repairs from pushing things past the edge.

absolutely correct!

[Darth_Emma]

Does adding a cam generate a lot more heat? I am looking for my next engine mod and I'm thinking of a cam and/or supercharger. I know a supercharger can make it get VERY toasty in the engine compartment. I wondered if a cam does the same?

I had my headers ceramic coated (with 2000 degree coating) in anticipation of adding more horsepower to help with heat in the engine compartment. I am just trying to figure out whether to get a cam and a supercharger or just one of them.

I'd love to hear the pros and cons of each. I suppose heat is just one issue. I do know that I LOVE the sound of some of the cammed cars. I do NOT want to go overboard with a cam. I would want one that keeps the car very drivable and reliable on the street.

My current engine mods are: intake, 1 7/8" LT catted headers, Borla Touring exhaust and a tune.

[RedJewelSS]

Originally Posted by Darth_Emma

Does adding a cam generate a lot more heat? I am looking for my next engine mod and I'm thinking of a cam and/or supercharger. I know a supercharger can make it get VERY toasty in the engine compartment. I wondered if a cam does the same?

I had my headers ceramic coated (with 2000 degree coating) in anticipation of adding more horsepower to help with heat in the engine compartment. I am just trying to figure out whether to get a cam and a supercharger or just one of them.

I'd love to hear the pros and cons of each. I suppose heat is just one issue. I do know that I LOVE the sound of some of the cammed cars. I do NOT want to go overboard with a cam. I would want one that keeps the car very drivable and reliable on the street.

My current engine mods are: intake, 1 7/8" LT catted headers, Borla Touring exhaust and a tune.

so long as you pick the right cam to run with a supercharger.

[Raven02TA]

a cam will NOT generate more heat. the SC will. you have to pick which rt you want to go. a s/c could never sound like a n/a cammed car.

you will have to decide this. if you are going to stay N/A and want the sound of a decent cam.... or if you will be going s/c and get a cam right for your application.

if you were to pick a n/a cam. and then throw on a SC/turbo. you would essentially be blowing boost out of your exhaust too soon.

the below copy/paste was written for someone asking the same question but for a turbo. the SAME rules apply to S/C when speaking of cams, overlap, duration etc.

radical cams and turbo's/superchargers do not mix. here is the same info i used to choose a cam when i put together a customers turbo car (although it would be best to talk to some turbo car experts and explain your setup and what you want to achieve, and they can help you best decide the proper cam):

Make no mistake in the fact that the turbo cams are very different from atmospheric performance cams. The characteristics of long duration and high overlap for atmo cams are unwelcome in the turbo system.

The situation, when presented with long-duration, high-overlap cams, creates a huge amount of reversion. Thus the "turbo cam" tends to become a low duration, very limited overlap camshaft..

Duration:

Duration is critical to a turbo setup since its probably the single most important event of a turbo motor (i.e. time valve sits open and closed). Since the air is being forced instead of drawn into and out of the combustion chamber, duration will be your largest variable on how that incoming/outgoing air is managed.

Duration when using a manifold or log design on most turbo cams is usually about 6 degrees more intake duration than exhaust duration (226/220, 240/234). This is mainly because a manifold/log design will typically see higher then a 2:1 pressure ratio in the exhaust ( as high as 4:1 with some logs). By using a reverse split duration this will somewhat help prevent from getting exhaust gas reversion.

Duration when using an efficient header setup with most turbo cams will usually be (230/230, 224/224) or better known as a dual pattern cam. The thinking is with the exhaust backpressure being only 2:1 you can leave the exhaust valve open a little longer then if the exhaust backpressure was 3:1 or higher. Also some of the new turbo designs produce a much lower backpressure with the advent of better flowing turbine wheels and housings which further decrease the total amount of backpressure created by the system.

Overlap:
Overlap definition, is the time period when both the exhaust valve and the intake valve are open at the same time. The exhaust valve needs to stay open after the piston passes TDC in order to use the vacuum created of the exiting exhaust gases to maximize the amount of exhaust gas drawn out of the cylinder. The intake valve opens before TDC in order to use the vacuum created by the exiting exhaust gases to start drawing the intake charge into the cylinder.

This sequence of events above are controlled by the duration and LS (Lobe separation) of the cam. On a typical N/A motor this is essential since you have no pressure being developed on the intake side to push the charge into the combustion chamber. The problem with this event is a turbocharged motor will create a larger amount of backpressure on the exhaust side. Due to this event the above definition will not apply. Reason being is, when the intake valve opens at BTDC, the burned gasses in the chamber will exit out the intake since the pressure is lower than the exhaust. Since this is true you would not want to open the intake valve until the piston has started going down, ATDC. This will lower the combustion chamber pressure till it's below the intake manifold pressure.

To calculate the overlap of your cam simply follow these steps below:
**Example turbo cam:**

Duration @ .006 218/212

Lift .544/.544 lift

Lobe Separation (LS) 114

Add the intake and exhaust durations
Divide the results by 4
Subtract the LSA
Multiply the results by 2

Overlap is -13 Degrees of overlap

Above was the process on how to calculate your cams overlap. As you can see, the overlap in the 2 cams differ greatly. Running the N/A cam example on a manifold setup would be a horribly in-efficient setup and the engine would be operating well below its potential output. While running the example turbo cam would work well even with the most in-efficient of the header systems out there. Typically a overlap spread of -8 degrees to +2 is a safe bet. Of course this will differ with whatever combination header, turbo and exhaust is used, so those #'s could be higher or lower.

Lift:
How much lift should I get in my cam? Well that will depend on your heads' flow characteristics. To choose the correct turbo camshaft, you really need to know how your cylinder heads flow. Reason is if your cylinder head flows X amount of air at X amount of lift, choosing a cam that has a lift much greater then that will gain you nothing except extra heat and premature wear of the valve spring. Airflow through a head reaches a peak as the valve is opened, then starts to drop off as the valve is lifted beyond that peak. Most of this of this will hold true to definition, but with a forced induction motor, valve lift is not as critical since the incoming air is pressurized.

A good rule of thumb is to select a cam that will lift the valve 20-25% past its peak flow point.

So be the definition above if your head flows best at 0.500" of lift, use a cam that will lift the valve between 0.600" and 0.625". The reasoning behind this is, if you lift the valve only to its peak flow point, then the valve only flows best when it's wide open. The cycle is brief and would only happen once per stroke. So to benefit from you peak flow the most, you want to lift the valve past its peak. That way the valve will pass its peak flow twice in the cycle. The result is more flow during the opening and closing event of the valve. You do not want to raise the valve much past the peak flow though, or you lose total flow by going too high.
Calculating the best lift:

0.500 X 1.20 = 0.600
0.500 X 1.25 = .0625

Conclusion:
There are way too many factors to just say XX cam will make XX power with your combo. Things like "114LS is best, or 117LS, or ..etc", are just blanket statements. Backpressure, RPM range, boost level, target horsepower, A/R of turbo, turbo frame (T3, T4, T6/Thumper), head flow, cubic inches, and even location of turbo...etc. All of these factors are extremely important in determining the cam that best suits your needs. There is no rule of thumb with a turbo cam. There are too many variables and the only way to get the right cam is to take all of those your parameters into consideration, and only then can a proper cam be selected. All of the points of reference above are just to get you on your way to building the best and most powerful turbo system for you. Study your design and ask questions along the way and you will be smiling the next time your opponent lines up next to you.

[Darth_Emma]

Raven02TA:
Thank you so much for all of that valuable information. I am not going to dive into making these decisions right away. I obviously have a lot of homework to do first. I have been asking questions of a lot of the experts about cams and superchargers. I have found that everyone seems to think they have exactly what I need for my application. I think that's great, but I need to make sure I know what my needs are first. I will be doing a lot more homework before making any final decisions about cams and superchargers.

It's folks like you who make this site such a valuable place. Thank you very much for helping me on my way to making an informed decision.

[Raven02TA]

Very welcome. hope this helps put you and others a step in the right direction. i was in the same position as you once. thinking big cam/SC/TC, and of course everyone said "oh i go a cam i can sell you" or "i have a cam i can install for you" (little to their knowledge i did my own installs and builds)

just browse around forums and do some reading. it'll take a while. dont be afraid to call some shops like Va speed, or texas-speed, thunder racing etc and ask a tech for advice.

[Dr Jkel]

Raven,

I too really appreciate the info, I got my parts Friday and they are being installed now. Based on the information I gave the supplier I got a cam that the installed said was real mild, which is what I wanted, can't remember all the numbers but I think 112 is the LSA.

My question is what makes the sound. By this I mean the overall sound. My nephew has 850rwhp and it sounds like a NASCAR and you can't hardly ride in it. At the shop on Friday they had a GTO with the LS2 and it shook the ground.

So is it the headers, cats, x-pipe, mufflers or what that makes the overall sound. I talked with the GTO owner and he said it was grossly loud inside the cabin. This is what I am afraid of, too loud to ride in. The bad part of the mod thing is unless you hear exactly what you are getting in person then there really is no telling, internet give a good idea but you never know about the video quality.

[Raven02TA]

the sound is mainly effected by your exhaust. it all depends on the combination of exhaust parts you have on the car. Headers/X or H-pipe will certainly make it louder but the muffler give you your pitch for the part.

the cams LSA will decide ho much "lope" it has. usually factory cams are in the 118 LSA range. a 114 will be slightly noticeable. a 112 of course more so. and with guys like me who have a 110 LSA cam. it is VERY pronounced. a cam will help make things a tid bit louder since it is letting more exhaust out than factory. but the combination of exhaust parts is what really decides it.

for instance. i have 1 7/8" long tubes, a Catted Y-pipe, with a factory WS6 catback. but mid pipe i have an electric cutout installed. when the cutout is open the car is loud. (not obnoxiously) however when i close it. the car sounds nearly as quiet as the day i bought it new.

in the video below i closed the cutout around 1:25

[Dr Jkel]

So If I have stock mid pipe and axle back exhaust it should be kinda tame? Headers and HF Cats.

[Raven02TA]

Originally Posted by Dr Jekel

So If I have stock mid pipe and axle back exhaust it should be kinda tame? Headers and HF Cats.

yes it would be pretty tame and would be relatively close to factory "tone" just louder.

Originally Posted by Dr Jekel

so mine has a LSA of 112, but was told it was mild,
is this true? I think the other numbers were 221/230 maybe and I cant remember
the lift. I guess I will definitly know tomorrow, lol

the LSA doesnt actually decide whether or not the cam is "tame" all the numbers together
pretty much decide it. The LSA only decides the angle at which your lobes are
seperated creating the "cammed" sound.
(however the choppier the cam is. the less streetability you will have) 114/112 are usually the LSA of choice.

[DSteck]

Overlap dictates lope more than LSA. Overlap is simply a byproduct of LSA and intake/exhaust duration.

A 221/230 on a 112 split only has 1.5º of overlap, which won't give that hard choppy idle.

There are other factors that can impact the sound, too. Your headers can change tone (when I moved from 1 3/4" to 1 7/8", mine got a lot deeper). Your compression can affect the pop of the exhaust... Below, my LS7 is still near 11:! compression, while that LS2 has a much higher 12:1 (roughly). The higher your compression, the more of a pop sound it'll give. It's hard to explain in typing.

A 23º overlap cam in an LS7 (mine):


A 18º overlap cam in an LS2 (buddy's):

[JR-Vette]

A CAM can cause more heat, depending on duration/ lift and more air mass the leaner cylinder charge is causing more fuel added, the total will increase more overall heat. Add long tube headers and more overall engine bay heat.
More HP, the more heat and why sparkplug vendors make several steps of colder plugs and heat socks for sparkplug wires.

The more load on engine produces more heat, superchargers will increase overall and intake air temps.

Originally Posted by Darth_Emma

Does adding a cam generate a lot more heat? I am looking for my next engine mod and I'm thinking of a cam and/or supercharger. I know a supercharger can make it get VERY toasty in the engine compartment. I wondered if a cam does the same?

I had my headers ceramic coated (with 2000 degree coating) in anticipation of adding more horsepower to help with heat in the engine compartment. I am just trying to figure out whether to get a cam and a supercharger or just one of them.

I'd love to hear the pros and cons of each. I suppose heat is just one issue. I do know that I LOVE the sound of some of the cammed cars. I do NOT want to go overboard with a cam. I would want one that keeps the car very drivable and reliable on the street.

My current engine mods are: intake, 1 7/8" LT catted headers, Borla Touring exhaust and a tune.

[Dr Jkel]

Originally Posted by Raven02TA

yes it would be pretty tame and would be relatively close to factory "tone" just louder.



the LSA doesnt actually decide whether or not the cam is "tame" all the numbers together
pretty much decide it. The LSA only decides the angle at which your lobes are
seperated creating the "cammed" sound.
(however the choppier the cam is. the less streetability you will have) 114/112 are usually the LSA of choice.

I am pretty sure that I got these numbers wrong. I didn't write them down when I got my cam just took it to the shop to be installed. I have had so many cam numbers in my head the last three weeks I can't remember them all. I want to say 227/239 is more around the numbers but can't be exact and the other numbers are around 617/624 but again I am not sure.

[Dr Jkel]

The more I read the more confused I get, LOL Mine should be done today. I have to honestly say that I really appreciate the help. It seems that the more people say the more I seem to not understand. Some say LSA causes lope, some say the duration and some say the lift.

I think alot goes into choosing a vendor on things like this, ESPECIALLY, when you are a Noob like me at these things. I told my vendor what I wanted, the sound I wanted, how I wanted the car to drive, with respect to cabin noise, and basically everything I wanted and what was important to me, dependability, reliablility and of course that certain little sound I want. Not a junker sound but a cool muscle lope, not like the car is going to stall but just a nice little bump, the added horsepower is just icing since I will not be racing my car at the strip, maybe just suck up some from 35 to 65.

Today I will know how I have faired because the install is supposed to be done and I am supposed to pick it up this afternoon if all goes well. I will actually be amazed if it is exactly what I want. The only reason I say this is not doubting the vendor, but for someone to take what you tell them, without actually hearing what I have pictured in my mind, and providing a product to achieve that, well Amazing is the only word I will have. Especially since the vendor is not located anywhere near me and I am having to have someone else install it.

I am not sure on cam spec and really could care less, I pretty much know I am wrong on the specs, but I have faith in the vendor so we will see. I will say this if he pulls this off I will sure be singing his praises. Come one 3:00 pm, lol

[Darth_Emma]

Dr Jekel:
I'm anxiously awaiting your report on your car. Did you get it back? How do you love it? I am very interested to hear what you think. I need feedback!

I'm so confused about cams and superchargers now. I have a whole lot of reading to do.

[OrangeFury]

Probably a dumb question and perhaps one that has been answered before:

Do CAI, Exhaust, etc mods void your manuf. warranty?

[Dr Jkel]

Originally Posted by Darth_Emma

Dr Jekel:
I'm anxiously awaiting your report on your car. Did you get it back? How do you love it? I am very interested to hear what you think. I need feedback!

I'm so confused about cams and superchargers now. I have a whole lot of reading to do.

Got it back tonight will post more tomorrow am, will post everything you might want to know around 6:00am CST 5-20-10, I think you will learn alot from my post but it will be long

[Dr Jkel]

Originally Posted by OrangeFury

Probably a dumb question and perhaps one that has been answered before:

Do CAI, Exhaust, etc mods void your manuf. warranty?

not necessarily, if you have to have your car tuned it will.

[camarohead]

Originally Posted by OrangeFury

Probably a dumb question and perhaps one that has been answered before:

Do CAI, Exhaust, etc mods void your manuf. warranty?

a catback or axleback wont for sure. a cai shouldnt but if u have a really anal dealer, like mine, they may void it. if you want to keep the warranty, i would ask the dealer what will and what wont void the warranty.