Are they worth putting on?

 

No

Here is what works.

Remove cats or go hi flow.
Install dual outlet mufflers.
Long Tubes (I don't like them on street cars)
Aluminum under drive pulleys
1,6 RR's
Remove your frisbee
Throttle Body bypass
Cut air filter lid

Some of these are very minor but add up and are cheap and easy.

 

Thanks BADDUCK, I’m not totally up on some of the lingo?

Remove cats or go hi flow – Where can I get a pipe to omit precats?

Install dual outlet mufflers – Has Eliminators

Aluminum under drive pulleys - What are they?

1,6 RR's – Ditto ???

Frisbee – Done

Throttle Body Bypass – Done

Cut Air Filter Lid – Done

 

I just went to a muffler shop and had them cut off the precats and sleeve the pipes. Also get a hi flow main cat.
March makes aluminum 3 piece U D set called Power & Amp with a smaller alt pulley. You will need a new belt as well. They claim 8 HP. For sure you spool up quicker.
1.6 Scorpion full rockers is what I used. They will increase valve lift and lighten your valve train. Do some searches. You will want new valve springs.
Eliminators are fine.

 

At the top of this tech section of the C4 forum are special posts called "stickies" this where valuable and correct info has been collected and permanently posted for all of to read and gain knowledge. Look at the stickies particularly the one 5th from the top that says "links to old tech tips" and also the 3rd from the bottom that says "C4 technical summary" read these and you will gain a wealth of info on what works and what doesn't.

 

=Remove cats or go hi flow – Where can I get a pipe to omit precats?
Have a local shop build up a set or check MAM for mandrel-bent front Y.

-Install dual outlet mufflers – Has Eliminators
For mufflers I like Flowmaster or Magnaflow.

-Aluminum under drive pulleys - What are they?
March makes a nice set: underdrive (smaller) crank pulley & overdrive (larger) alt pulley.

-1,6 RR's – Ditto ???
1.60:1 full roller rockers increase valve lift ~6.7% and duration at .050" by 2deg.

You might also install a 160 deg T-stat with fan switch and an AFPR to bump fuel pressure so fuel flow at WOT will match increased air flow.

Cut back the ground electrode to the inside edge of the center electrode on stock spark plugs will inprove the charge burn and bring a little HP gain.

 

read this website too....might as well be a sticky too.

http://temp.corvetteforum.net/c4/vader86/

 

Thanks for all the help! Good write up by Veder86’s he spells it all out.

I’ll be going with long tubes and no precats to start and take it from there.

What will I need to do if anything if I remove the main cat? We no longer have testing in Minnesota.

 

Doesn't Minn. have emission testing?

If so, you will need cats.

 

Nope, no emission testing here anymore

 

Are shorties worth putting on? I put them on for the following reasons:

1) The installation was just about a remove and replace the old cast iron manifold. No fabrication was necessary with the exhaust pipes.

2) The shorties reduce the heat in the engine compartment over the cast iron manifold.

3) They look much better than the old rusty manifolds

4) They do improve the quality of the sound

5) They do improve the exhaust flow, but not as much as the long tubes.

6) If you are looking for every bit of horsepower you can get, go with the long tubes. I wasn't looking for the fastest Vette, just a better running one that looks a little better, without the hassle of fabricating the exhaust. Shorties are used on many hot rods with nice results.

I know this is not what most Vette guys will go with, but I just wanted to give you the positive side of Shorties.

 

They can also weigh quite a bit less than manifolds and although that won't show up on a dyno it will show up in reduced ETs.

 

 

aftermarket shorties are better than the stock and flow better. But to gain something you can feel go with long tubes as TPIS as they are to bolt on with no mods other than replace the airtube to cat but if you do not have cat thats no problem. There is one headerbolt which must be torx or umbraco else it is straigt bolt on.
But whatever you do buy ceramic coated headers both inside and outside coating. That will decrease the heat tremendously and also ensure tethe heat is transferred through the exhaust making it more efficient

 

On my '95 the shorties were worth 9 rear wheel horsepower. Long tubes are not a Kalifornia smog legal option because the catalytic converter must remain in the factory location.

Not all shorties are created equal, some actually hurt exhaust airflow. When I installed the headers ~ 14 years ago I went through several brands before I found a well designed and well made LT shorty header

The ones I rejected:
1) One set had the wrong cylinder head flange port shape - they were not the "D" port and they blocked the very top part of the cylinder head port - which is the highest flowing most critical part of the port.
2) One set had the primary tubes pinched down to half size as they went into the collector.
3) One set didn't have the collecor in the right place, it was off center by more than 1/2" and would not connect to my head pipes/catalytic converters without some monkeying around and eliminating some of the factory catalytic converter bracketry.

I finally got a set made by Watson (NLA as far as I know), that were perfectly made without any of the above mentioned problems.

On the LT1/4 cars there is an alternative way to get the same horsepower increase while retaining the factory cast iron exhaust manifolds: eliminate/minimize the siamese center port. I.E., split it into two distinct flow paths. Easy to do, just machine a radial slot in the center exhaust manifold port top and bottom, then trim a piece of stainless steel to fit those slots and go as far as possible into the exhaust manifold. Until you do that the factory LT1/4 cast iron exhaust manifold is essentially a three port manifold on an engine with 4 exhaust ports.

Thomas

 

I use Hooker Shorties and I noticed an increase on torque the second I left the garage.

If you dot live in California, go with long tubes.

 

Long tubes are not just for flow but for "scavenging". This is not what you get from shorties.

When the exhaust valve closes, exhaust pulse continues down the primary tube. Vacuum is created between the exhaust pulse and the valve. THis vacuum helps pull more air into the cylinder when the intake valve and exhaust valve are open at the same time.