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im thinking about getting a bigger cam (383) Please read!

2K views 10 replies 6 participants last post by  pepi 
#1 ·
Hi guys, i have a 383 that has been built pretty well for power. Right now its putting out 365HP and 427TQ to the wheels. At first I ran the engine on nothing less than 93 octane. Then as my wallet got thinner, i started using 89 and performance stayed the same and the engine never pinged or dieseled. I took a risk and added 87 to the 89 just to see what would happen. I decided i would add 87 to the tank until it started pinging or dieseling (if ever) and would add 93 to the tank to even it out if it did. Well now the tank has pure 87 in it, and ive been running it with 87 for a month now. Engine performance is the same and it dosent ping or diesel. Timing is set at 30 total centrifugal all in at 1600 rpm and 20 degrees of vacuum advance. This setup has been great for me!

Anyway, even if i have a straight pipe on this engine, it just isnt very loud. Today an LT1 w/ trick flow heads and a bigger cam fired up, and even with pipes all the way back, it was loud! And it wasnt annoyingly loud, it sounded great! I want that sound and realize that I need a bigger cam, but I dont want to go too big on the cam so I dont lose all the mpg i gained by using a t56. Basically my cruising speed is 1600 to 1800 rpm doing 70-80 mph. I dont want the cam to have to much overlap and have all my fuel going through the exhaust because the cruising speed is lower than usual carbed v8's.

Right now i have a comp cam 510/520 lift w/ 230/236 duration 112 LSA. What would you guys recommend for a nice cam that has a nice THUMP to it, that would also give me some more power on the top end? The engine has a holley double pumper 750 on it and its in an 87 trans am (about 3250LBS) with a T56 6 speed manual and a 3.42 torsen rear end. What do you guys recommend?
 
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#2 ·
My gut feel on this is don't mess with a good thing seems like alot of work for something that is doing so well for you??,,, :spank: but its your deal so,,,

you already have a pretty big street cam, can a bigger cam live with your compression ratio? what is it at?

you could look for a similar cam but with a tighter LSA for a more agressive idle.

2 more of my cents
 
#4 ·
more rpm would = detination

It's kind of tough to put an exact handle on your combo w/o knowing the static compression. The 383 tends to reduce detonation tendancies due to the dwell of the piston near tdc. The cam you describe doesn't start building cylinder preasure until the rpms come past 3000 up due to the overlap. Most likely why your combo is quiet is because that it's burning the fuel much better than you friends combo that's what makes all the noise anyway.
 
#5 ·
red65novawagon said:
It's kind of tough to put an exact handle on your combo w/o knowing the static compression. The 383 tends to reduce detonation tendancies due to the dwell of the piston near tdc. The cam you describe doesn't start building cylinder preasure until the rpms come past 3000 up due to the overlap. Most likely why your combo is quiet is because that it's burning the fuel much better than you friends combo that's what makes all the noise anyway.
:confused: Really?



Back to the OP, with such a low cruise RPM you don't want a larger camshaft, you can try holding the same intake duration and extending the exhaust duration but that will lower mileage. Narrowing your LSA will also lower mileage and make it harder to drive at that low of an RPM. To be honest it sounds like you have a really good combo, if you want a better sound try larger exhaust pipes and some good mufflers. Magnaflows make a sound that I LOVE and they are one of the least restrictive mufflers.

What are you currently running for pipes and mufflers? What size of headers?
 
#6 ·
ap72 said:
:confused: Really?



Back to the OP, with such a low cruise RPM you don't want a larger camshaft, you can try holding the same intake duration and extending the exhaust duration but that will lower mileage. Narrowing your LSA will also lower mileage and make it harder to drive at that low of an RPM. To be honest it sounds like you have a really good combo, if you want a better sound try larger exhaust pipes and some good mufflers. Magnaflows make a sound that I LOVE and they are one of the least restrictive mufflers.

What are you currently running for pipes and mufflers? What size of headers?
Right now Im running a 3" exhaust, y pipe going into an edelbrock true flow muffler w/ dual 2 and half outlets, w/ 4" tips. It dosent sound bad, but you cant even hear it at idle inside the car!
 
#7 ·
IS it possible for you to get true dual exhaust (no Y-pipe)? That along with some flowmasters will get you a lot of noise. I still prefer magnaflow but flowmasters will give you more interior noise than you want!

What size of headers are you running?

It looks like your money would be be spent on getting a better exhaust if you want more sound.
 
#8 ·
yes these cars can have true duals put on them, i run 3" true duals on my 87' camaro. but you will have to have it done at a shop, because it will be a custom exhaust. for mufflers i like Dynomax, for the money they are the best flowing mufflers, Magnaflow are really good but a little pricey too, i dont like flowmasters at all, they have proven that they dont flow nearly as well as some of the other companies out there (like the ones i just mentioned). i use dynomax bullets, 3" center in/out with a 4" outside diameter, my rear suspension is adjusted to about 1.5" higher too + i use a 28" tire. if your car still sits at the stock height then you will want to avoid all speed bumps, or you could even just use 2.5" duals and you should be fine, a 2.5 dual still flows enough to handle up to 500hp

get rid of the Y-pipe and make sure that you are running a decent 1 3/4" longtube headers
 
#9 ·
my87Z said:
yes these cars can have true duals put on them, i run 3" true duals on my 87' camaro. but you will have to have it done at a shop, because it will be a custom exhaust. for mufflers i like Dynomax, for the money they are the best flowing mufflers, Magnaflow are really good but a little pricey too, i dont like flowmasters at all, they have proven that they dont flow nearly as well as some of the other companies out there (like the ones i just mentioned). i use dynomax bullets, 3" center in/out with a 4" outside diameter, my rear suspension is adjusted to about 1.5" higher too + i use a 28" tire. if your car still sits at the stock height then you will want to avoid all speed bumps, or you could even just use 2.5" duals and you should be fine, a 2.5 dual still flows enough to handle up to 500hp

get rid of the Y-pipe and make sure that you are running a decent 1 3/4" longtube headers
Ive been thinking about lifting the car a couple inches for a while, do you have any pics of lifted trans am/ camaros? Im planning on going for 18" vette wheels. If i can lift it, ill go for 3" duals since i already have most of the piping.
 
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