red 1981

[walt12]

Just purchased a red 1981 coupe. I want to install new mufflers & cat. Any suggestions? I want to keep the noise level down but increase flow if possible.
Additionaly, what can be done to the engine, if anything, to increase H.P. slightly with out breaking my bank account?
Thanks,
Walt

 

[78SilvAnniv]

Welcome Walt

I'm sure you'll find CACC to be a friendly and helpful site. Come back often and tell us how you're doing with your '81!
Have you checked out the L81 Registry? Bud (Rare81) will give you more information about that group!
Heidi

 

[Yoda]

walt12 ~ Welcome to the Corvette Action Center Community ~

Just purchased a red 1981 coupe. I want to install new mufflers & cat. Any suggestions? I want to keep the noise level down but increase flow if possible.
Additionaly, what can be done to the engine, if anything, to increase H.P. slightly with out breaking my bank account?
Thanks,
Walt

Walt here are a couple past threads about the chambered muffler question Chambered Mufflers and here is one on Mufflers ..

If the state you live in lets you run without a cat.. you can install a straight through pipe, that seems to help also if you are handing around the engine you can install a set of 1.52 roller rocker, there are a few other things but it would cost a bit, these are a couple of quick items

Hey ... Welcome aboard, and Enjoy the Ride!

 

[sixty9vette]

You'll notice an improvement (over stock) by getting a Car Sound catalytic converter www.car-sound.com (it's claimed to have the best flow). Not that expensive, either. There's a guy on eBay that's been selling new ones for about $55, and I think they usually retail for $150 or so. http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=1860126107
If you want to remain somewhat quiet, the 3 chamber Flowmaster 50 should suit you. They also flow well and their website at one time showed a chart where they flowed slightly better than their louder 40 series (two chamber). There's a performance chip available from Hypertech, but it doesn't make all that much difference. Without getting into the engine, there's not much else you can do. The computer carb can't be modified enough for significant gains, and same with the ignition (but check things like your cap, rotor, plugs and wires. Stick with quality brands such as Taylor, Belden, or Morosso. I don't like Accel). You might notice a bit here & there, but the most significant will be the exhaust until you decide to drop a ZZ4 in there A Transgo shift-kit will help the TH350 a lot, and it's not that expensive.

 

[walt12]

red 81

Thanks Rare 81 & Chris 81 & the moderator for the helpfull info. I am decided to install a set of flow master 50s & a new free flow cat. Presently it is in the shop for a major tune-up, trans rebuild, body work and a few minor repairs. As you can see my bank account is taking a substantial hit. Love the car & cant wait get it on the road.
Thanks agin,
walt

 

[GerryLP]

easy add-on power

Walt,

The rockers replacement that Bud :BOW suggested is an excellent step in the right direction. Factory-stamped rockers rarely maintain a constant lift through its range, so a set of new rockers would be nice and cheap to add-on.

I, however, tend to modify the original equipment in my car with non-original internal components for my car's sub-components. The Dana 44 in my car has a 3.31 ratio. The tranny is beefier inside (including converter), and so on.

So I personnaly plan to rebuild my old and worn original engine with 1.6 ratio roller tip rockers. With a 1.6 ratio one can expect anywhere between 0.025" to 0.030" additional lift for the factory cam. The gains are not very dramatic, but in combination of reduced parasitic drag and additional lift one can expect 10hp gain. I am deriving this estimate from what I have read in Chevy High Performance magazine and others as well, but this is probably arguable :argue Anyways, L81's can notice a 10hp gain in our derated engines easily :cry.

Roller-tip rockers will still allow you to use the original valve covers. Full rockers, however, would require a bigger valve cover, and the A/C bracket will not fit (unless, maybe, you get a custom-made bracket). So if you want to maintain A/C, then stick with roller-tip or stamped rockers.

Right now my car will be travelling around :s with a non-factory short block and aluminum heads. Most of the engine components moved to my new engine, but I purchased the core cost on my new short block, so that I can retain my original block and heads. In the future I will make the above modifications and other additional ones, and eventually the original engine will return to my car as well.

 

[CharlesW]

I want to keep the noise level down but increase flow if possible.

Magnaflow gets my vote. Quiet, but not too quiet, and you can look straight through them. Seems like that should be good for flow.

Charles (newbie)

 

[jon81]

I went with the Mid America true dual exhaust with Flowmaster Delta 50's. I have about $450 in it including installation. Nice mellow sound that doesn't drive you crazy on the interstate.

 

[CharlesW]

jon81:
Where does the MAD true dual system fall in the emissions group? Two cats, or no cat? Is the '81 old enough to be exempt from having to retain the original emission equipment? True duals sound so much better, (to me), than the original setup, that it would be worth the money just for the sound.:t

Charles

 

[jon81]

Charles;

The pipes are catless. I live in WV and we don't have emissions testing. I don't know if you have required emissions testing where you live.

The sound is really nice with no resonance at cruise. The cheapest price I found on the Flowmaster Delta 50's was at http://www.racerpartswholesale.com/. I also added stainless exhaust extensions which gives everything a nice finished look.

 

[GerryLP]

what a goof!

I guess that I placed my reply above in the wrong thread. :duh

 

[CharlesW]

Re: what a goof!

I guess that I placed my reply above in the wrong thread. :duh

Looks like it is quite appropriate for the thread.

Charles

Walt12's question:
Additionaly, what can be done to the engine, if anything, to increase H.P. slightly with out breaking my bank account?

Rare81's answer in part:
also if you are handing around the engine you can install a set of 1.52 roller rocker

GerryLP's info:
The rockers replacement that Bud suggested is an excellent step in the right direction. Factory-stamped rockers rarely maintain a constant lift through its range, so a set of new rockers would be nice and cheap to add-on.

 

[Dave L.]

GerryLP- Maybe I asked this before but what crate engine did you put in your car? Keeping your original engine core and rebuilding down the road is a good plan. I am thinking along these lines for my car. I was considering the base level GM crate engine(#10067353) along with an upgraded cam. This way I could use my original valve covers,flywheel and intake manifold.

Dave

 

[GerryLP]

Burglar,

My experiment with my engine started as a Head and cam change. Evolved into an engine change, and It ended as a sound motor, but a costly one.

My engine is not a crate engine. It is a Hi perf. short block with edelbrock heads, Compcam HE268H, and it has a combination of stock parts (manifold, carb) together with after market parts (roller tip rockers, dual sproket chain, water pump, etc). The cam is based on my wishes for a 330 - 350 Hp engine that will still operate vaccum components. One can get more radical that this cam still.

I did it the hard way, for in my haste, I ended relying on a Speed Shop for the procurement of the components. The net result was a very strong 9.7 CR engine, but I probably could have bought a ZZ4 crate for the amount of money I have spent. Then the labor would have been on me.

Nevertheless, with the labor costs ($650.00 Complete), and incidentals (ARP hardware, hardened push rods, gaskets, and others) I probably overpaid nearly $1,000 by doing the engine A La Carte. The final total was $3,500, and although I have my original cam, heads, and block, the best choice would have been a crate motor (with GM warranty). I've spent GM's profits from a crate motor for a very strong and skillfull knowledge base (the speed shop), upgraded miscelaneous hardware, and a little micro-managing of my engine on my part.

I am very happy with my motor, and I am having fun tweeking it with more parts (WEiand manifold, Jet Performance computer chip, Hedman headers). Researched information here and through key individuals such as Rare81, Tom73, Stingray6974, 69MyWay, Evolution, and in fact the CAC and L81 community at large ).

Yes, crate engine is the answer, but I cannot readily help you on which to choose. Just think of what you want your engine to do and add a good 40% budget for incidentals/unknowns. Does it add to a crate engine, then buy crate engine and avoid the hassles.

As they say: "you can pay me now or you can pay me later, but pay me you will"... :cry