c4- exhaust

[grumpyvette]

theres plenty of math, but clearance issues, and packaging limitations, are the factor that limits what CAN, be done in most cases
I,m constantly amazed at the guys that seem to be limited in what they do,to their cars, by what some catalog suggests is the only option you have, available, the truth is that you can fabricate or modify a great many components to fit your car that are not
"OFF THE SHELF COMPATIBLE"
nearly anything in exhaust pipe, transmission supports mufflers etc, can be fairly easily modified to fit or a complete exhaust can be fabricated if you have some basic skills and a decent mig or tig welder or even an oxy-acetolene torch.

once you stop thinking that your only option is parts listed as direct bolt on replacements youll find a great many more parts can be made to fit your car very easily.

http://forum.grumpysperformance.com/viewtopic.php?f=56&t=1166

http://www.classicchambered.com/classic/products.html

http://forum.grumpysperformance.com/viewtopic.php?f=56&t=1730

yes I know some of you reading this would rather slit your wrists that read links, but try it, youll be amazed at what you can learn

http://victorylibrary.com/mopar/header-tech-c.htm

http://victorylibrary.com/mopar/cam-tech-c.htm



http://www.flowmastermufflers.com/mufflers.html

first ID advise STAINLESS as the material, because you don,t want to be doing this again in 3-4 years, an use of 2.5" minimum,pipe size helps a good deal, 0r better yet 3" IDEALLY for size on the pipes on a performance exhaust..especially with nitrous
the (X) (IDEALLY) (H) if forced , by clearance issues, should be as close to the header collectors as the available space/clearance allows, that's generally near the front u-joint due to the trans pan required clearances, the OPTIONAL second (H) to lower resonance, should be installed connecting the two exhaust pipes just in front of the muffler entrances

http://www.melroseheaders.com/products/smooth_flow_exhaust_systems/c-4.php

Id buy this or duplicate this EXHAUST,and add an (H) where it connects to the mufflers, similar to this

the second (H) goes a long way to destroy resonance

http://store.summitracing.com/partdetail.asp?autofilter=1&part=SUM-642030&N=700+115&autoview=sku

http://cgi.ebay.com/ebaymotors/JVT-93-9 ... ccessories

the idea is to minimize flow restriction and maximize cylinder savaging in the rpm range you'll operate in the majority of the time

 

[grumpyvette]

have you replaced the exhaust system on your c-4 corvette ?
you can do it your self if youve got some fabrication skills and a decent welder, or you can buy a pre-made system like the melrose one above,careful shopping will provide individual components.
many of you may not be aware that just as the stock TPI intake is restrictive so is the STOCK 2.25"/2.5" exhaust system, IN fact swapping it out for a 3" full length exhaust makes almost all other engine mods work better. with no other changes at all ive seen several corvettes pick up two tenths to a full five tenths in one case in the 1/4 mile by installing full length headers and a full 3" exhaust with free flowing mufflers, all the fancy engine parts in the world won,t help if the engine can,t breath!
while its technically illegal to remove the exhaust , emmision equipment , you can install the larger 3" exhaust anf free flowing cat(S) and an (X) or (Y) pipe as necessary if the old system is rusted out/damaged and by now most C-4 corvettes are pass due!
HERES SOME IDEAS

http://vsholley.vwh.net/HiOctn/ProdLine/Products/ES/ESHHA/SplitFlow.html

http://www.youtube.com/watch?v=6grztIXf ... re=related

http://www.burnsstainless.com/Transitions/transitions.html

http://www.racerpartswholesale.com/flomstr1e.htm


http://www.burnsstainless.com/Crossovers/crossovers.html

let me ask you this, "if opening up the headers at the track normally produces more hp and tq, what makes you think that going from a 3" header collector down to a 2.25" stock (Y) can do anything but RESTRICT exhaust flow?"
to answer your question even more directly, getting a 3" (Y) installed from the header collectors to the cat normally shows a gain in BOTH hp and TQ
look at it this way a 2.25 inch exhaust pipe with 14 ga wall thickness has about 3.8 sq inchs of flow area a 3" has about 6.5 sq" of flow area or about 70% less restriction, (thats per side, but at the (Y) its even less at the point they join, what do you think the results will be at high rpms where the exhaust volume increases a great deal? on my vette there was a very noticable increase in hp and no loss of tq after the swap to a full 3" exhaust!

a good amount of resonance in the exhaust can be canceled with (X) pipe installed close to the header collectors and a REAR (H) before the mufflers plus the cones in the exhaust tips
the CORRECT WAY is to install these, it does not effectively block the flow but does effectively alter the frequency of the resonance, lowering the noise a great deal with effecting the engines power output. on some systems installing one per side works on others it takes both exits with one installed but they do work quite well on most corvettes (they install in the exhaust tip)

each year c-4 corvette used a slightly differant EFI system and the O2 sensors varied as did the number used, on the 1985 theres only two,

your 1996 corvette uses (4) O2 sensors, theres one before and one after both cats,in the system, youll need to retain all four O2 sensors or youll throw trouble codes, bungs are easily welded into the exhaust system with or without the cats in the system.