Cjunkie

Mark IV BBC had the IE valve arrangement like Ford not the siamesed exhaust valve like the SBC.

barchetta1

I figure cam first and take it from there. No point in doing anything really until the cam is done. I just dont know how driveable it will be with a cam that lifts as high as that one does. I guess thats why I started this thread but it just didnt go in the direction I anticipated.. anyway, thanks for all the advice..

84 4+3

lift isn't everything. Duration and such also is. Is your car auto or manual. Six speed would be more forgiving as the auto you may need a stall. The hot cam isn't extremely aggressive. I mean it is but it's still on the milder side of what can be done.

What are your goals for swapping the cam? Comp has some videos on their site with some of their available cams. You could see what you like there and cross check on youtube. Don't do it just for sound is all I'm saying.

MatthewMiller

I agree with all of this. My car has long-tubes followed by a custom 3" exhaust with good aftermarket cats, an X-pipe, and then Corsa mufflers at the back. That rasp when he revs it is definitely provided by the X-pipe. I get compliments on the sound of my car pretty frequently.

I am actually surprised that the car in the video has as lumpy an idle as it does with just a Hot Cam. Maybe he has the idle as low as stock. I have considerably more overlap, but mine idles around 1000rpm to make sure it stays happy.

TKO Performance

JrRifleCoach

Brutal! Just BRUTAL!

barchetta1

I agree, I dont think its just a hot cam. My scca gt1 car had a very high lift/high duration cam and that is how it sounded. I wish I had my spec sheet but that was 26 yrs ago. Im gonna write him and see if he responds.

drcook

my 2 cents worth, just to muddy the thread up a bit (also I don't have speakers on this computer right now), but the sound of a built 327 through side pipes. that is my holy grail, ranking right equally next to a big block through headers, either mopar or chevy.

barchetta1

Link?

barchetta1

He explains some in the youtube comments

gyro9
5 years ago I started modding. I did the HotCam kit, which included the 1.6:1 roller rockers. Then, I replaced the stock exhaust headers with Stainless Works long tube headers. In addition, I replaced the original catalytic convertors with Random Tech high-flow bullet cats and replaced the resonator with a MagnaFlow stainless steel X-pipe. This winter, I installed new mufflers, the HOT (high output turbo) mufflers from CorvetteCentral.


For the HotCam, parts and labor came to about $1250. Total mods in the car now total about $7K.


When asked if he pulled the motor:
No, the motor wasn't pulled out, just lifted in front with a jack from below after loosening the front engine mounting bolts. Only the radiator and A/C heat exchanger were removed. Even the hood was left on.

The exhaust mods (see 'About this video' above) also had a lot to do with the sound, especially the mufflers and X-pipe.

Cam Style: Hydraulic Roller Operating Range: 1,800-5,800 RPM Advertised Duration: Intake 279 Exhaust 287 Duration @ .050: Intake 218 Exhaust 228 Lift with 1.6 Rockers: Intake .525" Exhaust .525" LSA: 112

The GM HotCam kit comes with the camshaft, 1.6 roller rockers, and valve springs. I don't recall the exact cost, but I think it was about $400. Installation was about another $1K. Before I did the headers, the cam alone didn't help very much. With only the cam, I took only 0.05 seconds off my best quarter mile time. After I did the headers, another 0.25 seconds came off. Most 'experts' recommend doing cylinder heads along with the cam, rather than doing the exhaust, for a better combination.

It's an auto. The chip that was in it during that video recording had an idle of about 800 rpm. I later replaced it with a 900 rpm idle to improve low rpm performance.

ghoastrider1

that last vette sounds great..like a vette oughta sound.

drcook

Sorry, this is the one that got away. I had to sell it when I was a single father, raising 2 children and we needed a house to live in. Seeing as how I don't have the money to purchase another C2, I will forever be chasing
the sound.

I will look and see if I can find a youtube vid with sound of a 327. They had a sound of their own.

While the firing order and such is the same, 327's, like the 302 engine developed for road racing and sold in Camaros are revvers.

The engines that are not muffled coming through cats and such had a different sound in my opinion.

Not having sound to listen, but here is a 327 pulling a 350. If I get a chance to do another car besides my '96 (which is an A4), I would like to get a '94/'95 M6 and have a 327 crank custom ground for it. Optionally, I recently read about a LSx based 327 engine (I don't remember the x designation) that pulled some pretty strong numbers. I was shifting at 6500 rpm (held it at that redline) at just under 110mph from 2nd into 3rd. While I know that torque gets you going, a high winding engine is fun.

MatthewMiller

I guess I didn't realize that the hot cam has that much advertised duration. I was always under the impression that it was similar to the stock LT4 cam, but it's a lot more cam than that. It actually has more duration than my cam, but considerably less lift (much less aggressive ramp rates). Mine has 108* LSA, though, so the overlap (at least insofar as it affects idle) is probably similar (mine should have a lot more overlap at .050", which is what really affects the power).

Going off on a bit of tangent here, but this is relevant if the OP is considering this cam. Just based on the numbers, it seems that the Hot Kit cam is intended for stock heads, with its relatively low lift. And it's wider LSA of 112* suits it to more stock-oriented cars, too, than my cam. While any engine benefits from better-flowing heads (without going into velocity vs runner volume), I would expect even an otherwise-stock LT1 to get faster with the Hot Cam. I thought that was kind of the point of the Hot Cam kit? Maybe that guy's exhaust (cats) was not working well? Who knows?

Mr. Peabody

So to go to the OP's original posted question..... the cheapest/most reasonable route to get to HIS desired sound.

I don't think that there is an inexpensive way to get there.

IMHO long tube headers are the most significant improvement you can make towards getting the lower rumble. That's originally why I got my Stainless Works header setup. I just loved the difference in the sound that one change made......... and headers alone won't require a re-tune on an LT1.

But to make the sound sweet you need a little lope and (again IMHO) you can't go wrong with the Hot Cam Kit ... although I think it now goes for quite a bit more than when the previous poster installed his kit. The nice thing about the kit is that if your not an expert all the parts are matched to perform properly with each other. Note my heads are stock.

To get the most out of the cam swap however you will need to have a tune done to the car. Back when I had this done ....... 70,000 miles ago ... I think I gained around 40+ RWHP on a mustang dyno. Mine was intentionally set to idle high around 700 - 800 for driveablity issues in bumper to bumper rush hour traffic.

I think my car sounds wonderful..... and while it wasn't inexpensive I'm still driving it briskly .. now with 135K on it

barchetta1

Thanks this is helpful. I dont mean to sound mean but this is the difference between an armchair quarterback and the real deal.

I cant help but assume you did more right off the bat though than just do your headers? Surely you changed your exhaust downstream?

I just cant seem to find anyone who left the stock exhaust in place and did the cats.. or left the stock exhaust alone and did LT headers.. but cant help but wonder what those to might sound like.

I did a lot of reading last night about exhaust systems and power and now am scared to death to touch mine which is 100% factory with no rust on it.

that being said, yesterday, in a cabin fever moment, I started her up with the garage doors shut. its sounded like a soccer mom mini van. IT HAS TO GO..

Im scared to death to mess with my unmolested 73k miles 96 but life is short. Im going get a few quotes on the hot cam install.. perhaps today whilst "working".

A few questions:

If headers are the key to the sound; how do I choose a set?

How do I choose a header back exhaust that works well with a cam?

What would the result be if I ran my stock exhaust be with headers, and perhaps no cats and a cam? Would it be too quiet?

How driveable is that car in the video I posted? Would I need to mess with the torque converter??

Would low end torque be hurt badly? Should I abandon this and go straight for rear end gear for now?

Anyone know where I can get a tune for a 96? what is involved? Is that a physical chip or a laptop upload?
thanks

MatthewMiller

For whatever this is worth, I did this with my old 89 Mustang, but I used an H-pipe with high performance cats. It sounded better than stock, a bit louder (but not much), with a nice burble. It wasn't close to that Corvette in the video, though. You'd probably like the improvement, but the raspy bark at high rpms won't be there. That really only comes from using an X-pipe. You could put one in place of your center resonator, which along with headers would really make a difference. Basically, you need to find a C4 that has long-tube headers but the stock cam to learn what it sounds like, and then go from there.

Definitely don't throw away whatever you remove. Store it in the attic or basement.

The first question you need to answer is whether or not you have to pass an emissions inspection where you live. If so, do they just plug the car into a scanner and look for trouble codes? Or do they do a visual inspection? If the latter, you need headers that have fittings for the AIR tubes to connect. You can make the car pass the scan test without AIR hooked up, but it won't pass if they visually look for the system to be in place and connected. Same thing goes for cats, btw.

If the visual test is not a problem, you can get plain headers, but they still need to have bungs for the pre-cat 02 sensors (car won't run right without those!). The bungs can be easily enough added by a shop, if they don't come that way. I'd review a few threads about different options - I don't know which are the best fitting and quality. I have Hookers on mine and they fit and work very well.

Really, after the headers you just want the most free-flowing exhaust possible, where performance is concerned. The other thing you have to consider regarding emissions testing is whether to use cats again or not. You can't pass a visual inspection without them, but you can make the car pass the scan. If you need to pass the visual exam, you will want a system that has cats in it. This is by no means the end of the world for performance. I have cats on mine, and it's loud and sounds awesome.

BTW, whether you have the AIR system and cats installed or not, you may need to turn off the after-cat O2 sensors. They will be considerably further from the engine and may not work properly, even if they are installed and plugged in.

It's probably still pretty good on drivability. You'll definitely want the idle closer to 1000rpm. I bet you can get away with the stock t/c - the C4s always seemed to have a little higher stall speed than other auto cars. You would definitely benefit from a looser one, if you ever wanted to up your game.

It will be a little less, but not as big a hit as some will have you believe. It's all a matter of degrees: if you have a 2/73 rear gear now, you would benefit from a shorter gear, but you can run the stock gear if you want.

Changes in tune are done by uploading a new binary file to the PCM, not with chips. The 96 cars are the first and only year of C4s with full OBD2. As such, there is only one software package now that will work with them, called Jet DST. It's not cheap, but it works well. You can do this yourself, if you're willing to invest the time to learn what changes to make. Or you can work with the guy at http://www.lt1pcmtuning.com/. With straighforward changes like headers and a Hot Cam, he probably has a very set of calibrations for you. The PCM calibrations is also where you turn off the tests for the AIR system and the downstream O2 sensors, if you need to do that.

barchetta1

This is great! thank you. Now I just need to put together a project plan with implementation path and costs.

I have a horrible gear in my car.. its a 2.56 I think.. or 2.54? Per the 96 spec I can find.. I have not rotated the wheels and counted the driveshaft turns to verify yet.. maybe next weekend..

Since sound/low end torque are my goals I may start with the exhaust and go from there.. only because it will give me a little instant gratification.. but its seams this is a package deal and aint gonna be cheap.

From a cost stand point I may never get there but at least I can dream.

MatthewMiller

It should be a 2.59 unless your car is a Z51 or otherwise had the "performance axle ratio." Upping that to 3.07 or 3.33 all by itself would make a real difference in how your car accelerates.

So the cam will make a real difference in how the car sounds at idle. But if sound is the only reason you would replace the cam, I would advise you to ride in some C4 automatics that have a similar cam installed first. You may decide that the downsides just aren't worth it. I addition to a loss of a bit of off-idle grunt, you'll have to deal with reprogramming, worse in-town fuel mileage, etc. OTOH, you could just do the headers and exhaust right now and avoid all the other mods, even including the tune (if you get AIR-compatible headers with cats and can make the downstream O2 sensors connect). Combine just the exhaust with a steeper rear gear, and you will have a better sounding car that is noticeably faster, for a whole lot less money and time/hassle than doing the cam. You can also add the cam later, if you have already done those things. It's just a question of how far you want to go with it all.

rblakeney

As I outlined in post number 5, I have gutted my cats and left everything else stock. My car has an L98 engine, however. I'm happy to attempt a quality recording if you would like to hear it.

rblakeney

Just found this discussion on exhaust sounds as well:

https://www.corvetteforum.com/forums...are-yours.html