What on these motors are extremely restrictive? I've heard many different parts.

 

The intake, the T pipe, the exhaust manifolds.

 

Intake as in manifold? or the entire thing starting from the filter to the TB and manifold/runners?
What about the stock cat/catback system?

 

Sorry, the intake manifold - specifically, the intake upper plenum transition into the middle runners.

 

Any other things besides intake manifold and exhaust manifold/y-pipe?

 

Those are the biggest things. Once those are done, then do a cam swap to take advantage of the added flow - P&P the heads, and increase the compression - you'll be all set then

 

Intake runners don't suck very good at all. There to small.

 

The #1 biggest restriction in the flowing of air/fuel mixture into and out of these motors is the head intake runner port. It has bend upward followed by an immediate 135* turndown into the combustion chamber. The floor of the runner port just before that bend has a sharkfin sylr vane on it that channels the gasses to the sides and top of the ports creating a low pressure zone behind it helping the gasses to "bend" the corner giving a 17% better flow than without the vane.

When air is forced into these heads via a turbo or supercharger boost, they respond very very positively in results over the ports sucking intake gasses and the #'s mulitply very rapidly with big HP gains over conventional 90* V6 and V8's in naturally asperated compared to force fuel results.

The very best thing to increase power is to increase flow. Supersix is the only company producing over-the-counter bench flowed heads with larger intake valves than stock. These heads with the larger valve option will greatly help a naturally asperated 60* v6 produce power under suction intake.

Exhaust side of the heads is fine and outflows the intake side by far.

 

The exhaust ports (minus the smaller valve) are all most a copy of what you would find in larger more power full engine, compairing by size shape and flow.
Some people don't belive in the intake port vane and claim higher flow bench numbers once it is removed. I like to leave it.
Remove it if you want a low end only engine, I think it helps flow more at higher port velocitys.

 

So for the most part..just the intake and exhaust manifolds.

 

Though Id put money into intake work first.

Biggest mod over stock that made a difference for me was
a "true" cold air ram air intake. On those hot summer days day with a almost 200F temp the old girl got real sluggish with the heat and hot under hood air.

now that I can keep a constant temp of 180-85 or less It run crisp and responsive all the time.

Get your temps under control in a steady zone and feed that suck cool fresh air.

 

man i gotta get headers....

 

Me too,but they are not smog legal for the 3.1's And no headers means no Y-pipe also I'll start working on the intake side then.

 

Are the stock cats or catback section restrictive at all? Pipe size and muffler/cat flow?

 

how can i get ahold of SUPERSIX, id like to just buy a set of good heads for my 3.4 instead of doing it myself(no time lol)

oh and arent pacesetters headers smog legal? that was the whole point of them making them, i could be wrong though

 

The Pace Setter headers are only smog legal for '85-'89 fuel injected 2.8L V6's that do not have AIR. There are no provisions on the headers for the AIR system used on the 2.8L, or the AIR system used on the 3.1L (they were two different setups).

They will bolt-up to a '90-'92 3.1L third-gen - but the CARB EO number doesn't cover '90-'92 3.1L cars.

 

wow thats pretty gay.....i thought that was the whole point of those things for all years...oh well good thing i dont need the smog cert.

 

nevermind i found it.....

http://www.supersixmotorsports.com/

looks like for a set of heads will be around 850, proted polished all that good stuff, im gonna see if i can send my manifold along with to have that matched as well when the time comes, i was looking to spend about that on my heads anyways and this way i dont have to do the work plus i know they will be done right

 

i heard somewher that they were making a set of headers with AIR compatability.

 

Or you can get the exhaust manifolds off of a 3100/3400 from 95-current. They bolt right up and have alot bigger ports and are designed better than the 3.1 and 2.8's You will have to have your down pipe modified a little bit to have it connected but it should give a few HP. Headers would be better though.

The whole top end is restictive on the 2.8 and 3.1's. HP occurs at about 4800 RPM on them. You can get alot more power with heads and intake off of an engine GM already makes. Ofcourse it probably involves more work than you wanna do. Esecially if you have a distributer. Unless you are rebuilding the engine when you tear into it. Because it involes a piston change. But that would also mean you aren't on a budget.


I just noticed you are working on a 92 V6 RS. They have DIS correct? Which are you building a 3.1 or 3.4? Either way you can switch to 00+ 3100 or 3400 aluminum heads with a P&P, intake, and the corresponding pistons. A nice cam. Either stick with flat tappet (requires custom length pushrods) or go for a roller. Some pistons to set you at about 10:1 Compression and some headers and you are looking at around 200 HP.