i have a 1987 TPI Corvette
but it does not sound like the old muscle cars
is it because the fuel injection ?

Nope. induction has little to no effect on exhaust tone.

my 87 L98 does not sound or idle like the old school 350's
i dont know why

the camshaft has a big part of it

the on board computer controls all the fun stuff. if you wanna make it sound old school then strip out the computer and go with a carbed engine and ruff idel cam

its because of the computer controlling timing ?
i have a zz4 cam
thanks

The ZZ4 112* Lobe seperation angle cancels out much of the lope your looking for.

Wide LSA camshafts definitely smooth out an idle, but so does a well set up EFI. I've seen carbureted cars with hairy idles get tamed pretty decently with a good EFI setup.

EFI can tame a cam a little, but your TPI's engine doesn't sound like a muscle car because it isn't. Muscle cars had 10.5:1 compression and cams with 110 LSA. Your TPI has 8:1 compression and a 117 LSA.

Yup, only thing that effects sound are the exhaust valve timing and the exhaust system.

Well, there are a few thousand things that affect sound. Cam grind is a huge factor. The air filtration can have an affect on things at WOT. Exhaust, engine geometry (inline? V? bank angle?), head design, compression, engine composition (iron or aluminum), firing order... the list is huge.

But, if you want your small block to sound like a muscle car, you'll need a comprehensive set of upgrades; head work, possibly pistons, and a repreduction cam. Only expect the sound, however. Don't expect much more power. Muscle cars were hot for their time, but by today's standards they aren't that spectacular. If you think about it, today's chevy small block gets 505 hp naturally aspirated with a silky smooth idle, nearly silent running, and gets almost 30 mpg in the vette.

Take advantage of today's cam, intake, and head technology and I think you'll be well pleased. Yesterday's muscle car sound came with about 1hp per cubic inch and was measured on an optimistic gross scale. Today's same sound can come with 2hp per cube measured much more accurately.

A set of Flowmasters (if you can stand the drone at highway speeds) makes them sound pretty good.

Mostly the cam, modern cams have little to no overlap regardless of how much duration. This takes a lot of the rumpity rump sound out of the idle.

Bogie