OzzyTom

Bee Jay...

What's with the squeal under full throttle?
Is it a loose fan belt or is it your converter or trans?

Very audible even over the exhaust .....

pauldana

how much $$?

sfrank2886

Yes, how much for x pipe and extensions to collectors to the front only? I am interested. Also looking to add this to hookers 2456.

larryg3

nice set up pauldana

Bee Jay

Update, I replaced the two Flowmasters with one dual in dual out Magnaflow muffler. I saved 25lbs. Check out this thread:
http://forums.corvetteforum.com/c3-t...w-exhaust.html

gkull

If you would also do the 4-7 firing order cam swap it would even sound more like a Ford

Bee Jay

What else does the 4-7 swap do other than changing the sound? More power? Smoother running? Better gas milage? More torque? Better exhaust scavenging? I can't seem to get a straight answer. I know that GM did the 4-7 swap on the new LS engines. Why? You know me, I'll try anything once, twice if I like it.
Bee Jay

LancePearson

Here is a link of photos on vir with a sound clip of my 76 with new straight duals through twin bullet ceramic grid cat converters and into flowmasters which are great so long as you don't drive at 32 mph where they drone. deep sound and when at highway speeds it's all left behind you but winding up through the gears it sounds good...no H or X pipe on mine. the clip is the music to the photo slideshow and is a recent local drive sound clip. Got rid of the 2-1-2 through pellet cat converter...yuk to the EPA.

http://albums.phanfare.com/slideshow...T&a_id=5066328

gkull

The local chevy drag race shop that has two cars that compete on the national level of NHRA sportsman racing told me "No Difference" These guys make their own sheet metal intakes and us up to 1.000 inch lifts in small block chevy motors that do 10,000 rpm.

His only disclaimer is that mildy modded carburated motors with single plane intakes tend to run #7 cylinder leaner and the 4-7 helps balance this out. In a sequential fuel injected motor this would not matter.

So the gain is the exhaust sound. When you are timing cars flying by on the main straight wall The Fords and 4/7 swap chevy motors just have a nice scream to them at 8000 rpm compared to the chevy small and big blocks.


IMO - your best gain would be a stroker crank.

Bee Jay

Yep, my dream is a Dart or World aluminum block stroker engine around 427 cubic inches. When I find the block, and the internals to go in it, your building the engine for me, or at least help me build it. I just haven't formally asked you yet. Are you doing the C3 run on April 30th?
Bee Jay

eastltd

Who's system is this?

AZDoug

I am a little late to this thread, but adding an H pipe, of the same 2.5" diameter as the rest of the exhaust system, about 6" from the header collector, gave me an extra 125 ft-lb of RW torque at 1500 RPM up through about 3000 RPM, where the effect started to rapidly go away and everything equaled out over 3500 RPM vs no H pipe.

Doug

couperdecar

An extra 125 ft-lbs of torque? Is that a miprint or is that real? If thats real I'm thiking thats going on my 'must do' list. Anybody else have that big a jump in Rear wheel torque?

AZDoug

It isn't a misprint, it was actually 175 more ft-lb,

The H pipe, on my motor, no other changes, raised the RWTq to 400 ft-lb at 1500 RPM on the small block in my '61, and also got rid of an annoying reversion issue at around 2300 RPM. This is an EFI motor, but that mainly has to do with tuning.

1.62" hedman headers, full 2.5" exhaust out to the behind the rear wheels with Borla muffs

It is a pretty quick, yet mild mannered, street car

Doug





Doug

Danish Shark

It's a DIY job, and since it's made i Denmark you don't wanna know what it cost