a well designed c4 exhaust

grumpyvette

Administrator
Staff member
theres plenty of math, but clearance issues, and packaging limitations, are the factor that limits what CAN, be done in most cases
remember an internal combustion engine works by use of producing rapidly expanding gases over a piston to produce pressure that forces the piston to spin the crank, those gas pressures exceed 600 psi and over 1000F temps, a well designed exhaust system will have a low enough restriction to exhaust flow that the max positive pressure will remain below 2 psi at peak rpms, and ideally less

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

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

http://www.corvettefever.com/techarticl ... index.html

viewtopic.php?f=56&t=91

http://www.corvetteactioncenter.com...xhaust-that-gains-28-hp-and-is-quiet-512.html

MOST OEM CORVETTE EXHAUST SYSTEMS, AND SOME AFTERMARKET, ARE HIGHLY RESTRICTIVE
http://www.corvettecentralexhaust.com/c4/stock/systems/

http://www.parts123.com/parts123/yb.dll ... 000050Q~~~

http://www.parts123.com/parts123/yb.dll ... 1~cadefibQ

Id also point out that cam timing matched to the exhaust scavenging has a huge effect on potential intake flow rates
exhaustpressure.jpg

EXFLOWZ4.jpg

pistonposition2a.jpg


first ID advise STAINLESS as the material used in an exhaust and 2.5 minimum,pipe size 0r better yet 3" pipe size aft of the header collectors feeding into the (X) pipe, IDEALLY for size, on the pipes on a performance exhaust.especially with nitrous and ideally with
the (X) pipe located as close to the two header collectors as under the car clearances allow.(IDEALLY) if your forced to use an (H) pipe and ONLY if forced, by clearance issues, it ,should be as close to the header collectors as the available space/clearance allows, also, thats 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


c_4_system.jpg

c_4_system.jpg

The melrose exhaust is a very well designed system, and keep in mind the exhaust gasses travel to the rear and pass through the (X) pipe they dissipate HEAT and loose some pressure and volume as a result, the (X) tends to mellow the growl slightly also, thus the two exhaust pipes past the (X) pipe share the split flow ,thats now sharing twice the original exhaust cross sectional area, at a reduced restriction, if I had the cash available thats the route ID suggest going , then you just need a decent quality, low flow restriction set of mufflers, added to the exhaust
Id buy this or duplicate this EXHAUST,and add an (H) where it connects to the mufflers, similar to this
wlk-40313.jpg

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

viewtopic.php?f=56&t=10419

the idea is to minimize flow restriction and maximize cylinder scavaging in the rpm range youll operate in the majority of the time
 
Last edited by a moderator:
NANCY said:
What is the stock stall speed for a '85 Corvette 700R4?
and what can I do to boost the responsiveness, or way it responds when I jump on it without throwing huge amounts of cash into the project? Thanks,

most early TPI stock converters on stock TPI engines stall at about 1900-2000rpm,the stock TPI intake,manifold design , while very effective at producing low speed torque, is very restrictive to air flow above about 4500rpm as it was designed for a 305 displacement engine originally, and the cylinder heads, cam and exhaust are all very restrictive to air flow over 4000rpm, and the stock cars came with pathetic 2.57:1-3.07:1 rear gears too increase or add decent mileage and reduce emission test results at the expense of performance.
keep in mind that what goes in , needs to exit at a low restriction or it reduces the potential power and that your engines generally far more efficient in the mid rpm ranges at producing power, so keeping it there as much as possible helps your car run more effectively, in that theres more efficient use of available power.
c4engine.jpg

volumetric.gif

swapping to a 3.54:1-3.73:1 rear gear and a 2800-3000rpm stall converter even with the stock engine gives a very noticeable improvement in performance but requires an additional trans fluid cooler,and benefits a great deal from a cam upgrade

on the early flat tappet cam TPI versions the crane 114132 has proven to be a trouble free and welcome upgrade worth 30-35 hp and its especially effective with 1.6:1 roller rockers and new valve springs and long tube headers
crane114132.jpg


RELATED INFO
viewtopic.php?f=55&t=10494&p=44299&hilit=tuned+port+restrictive#p44299

viewtopic.php?f=80&t=10514

http://garage.grumpysperformance.co...rger-intake-runners-l98-tpi.13785/#post-70716

viewtopic.php?f=55&t=1509&p=3459&hilit=base+runner+plenum#p3459

viewtopic.php?f=80&t=10433&p=43428&hilit=tuned+port+restrictive#p43428

viewtopic.php?f=56&t=495&p=35063&hilit=tuned+port+restrictive#p35063

viewtopic.php?f=56&t=1503&p=3419&hilit=tuned+port+restrictive#p3419

viewtopic.php?f=32&t=546&p=685&hilit=tuned+port+restrictive#p685

viewtopic.php?f=71&t=741

viewtopic.php?f=52&t=1070&p=35188&hilit=volumetric#p35188
 
Last edited by a moderator:
I replaced my from Y pipe a while back due to a rattling pre cat. I went with the Magnaflow 93987. Nice mandrel bent piece. Here's some comparison pics with the stock unit. The crimp bends on the stock unit are a performance killer. I do notice a little improvement on the low end, feels more torquey. Also noticed a very slight increase in drone around 1400 RPM, It's not horrible and something I can live with.
http://garage.grumpysperformance.co...reasonable-mild-but-dependable-upgrade.12130/
When I got the car it had muffler eliminators on it. Like these, http://www.ecklerscorvette.com/corv...less-steel-quad-zr1-style-tips-1984-1991.html It has a nice rumble at idle.
25-11310.jpg


Grumpy, have you used muffler eliminators on you C4's? If so, whats your thoughts of them?
 

Attachments

  • Last Import - 1.jpg
    Last Import - 1.jpg
    59.5 KB · Views: 27
  • Last Import - 2.jpg
    Last Import - 2.jpg
    58.6 KB · Views: 27
  • Last Import - 3.jpg
    Last Import - 3.jpg
    54.6 KB · Views: 27
Last edited by a moderator:
Exhaust noise is the perceived vibration or resonance caused by the high pressure pulse of exhaust gases exiting the engine in strong intermittent pulses that match the engine rpm, you reduce the perceived noise by absorbing or dissipating the strength of the individual pulses and by damping or blending the low and high pressure peaks in the pulse strength, this has been well proven, to be helped by adding an (X) pipe to the exhaust as it effectively doubles the cross sectional area,of each header collector if the exhaust pipes are the same diameter past the (X) thus instantly reducing the gas velocity and blends the pulsed thus effectively changing the two exhaust pulse per cylinder bank per rotation into four less intense pulses past the (X) pipe , this also tends to equalize the exhaust flow rates, reduce flow restriction and thus change and in most cases MELLOW or LOWER the strength of each individual pulse by interrupting the original frequency range caused by the engines exhaust pulse strength in the process.
v8-sound.png

Ive found that mounting DUAL in series (X) pipes has both a slight beneficial increase in exhaust scavenging, and a noise reducing tendency, the use of dual in series (X) pipes, very defiantly changes the rpm range and tone of any exhaust note!
for those guys who are less than familiar with math,or exhaust physics,
that might be thinking why did he go from a 3" exhaust pipe entering the muffler ,
to dual 2.5" pipes exiting the mufflers remember the exhaust pulsed enter the exhaust header primary pipes ever 90 degrees of engine rotation, these pulsed masses of exhaust gases
travel rapidly to the header collector then exit and the gases enter the approximately 7 square inch area cross section on the exhaust pipes,
they travel to the first (X) where the mass splits into a dual exhaust with each side having that approximately 7 square inch area cross section on the exhaust pipes,
each 3" exhaust sides flow mass has been reduced to half its original volume but now flows at a reduced speed to the second (X) where the pulse energy , now equalized and reduced now collides
this further equalized the flow as it temporarily recombines and re-splits, this further stabilized the pulse into a more consistent flow, the sound energy has been partly eliminated as the two (X) pipe intersections allow both sides of the exhaust to blend and lower the effective speed and restriction to flow.
now the mass of gas that was blended twice and has lost much of its heat, pressure and energy exits, that approximately 7 square inch area cross section on the exhaust pipes, into the muffler where its further cooled, slowed as it expands and can further reduce its speed and pressure as its now exiting a dual 4.9 square inch or about 9.8 square inches

tubingsizeversusarea.png


dualxmod.jpg

xpipehel.png

several of my friends have chosen to install those muffler eliminators and obviously each of us has a individual tolerance for noise level and the type of exhaust note or rumble we prefer
I know many of the younger guys seem to like that raspy exhaust sound and I was amazed at how quiet the car actually is with no mufflers at all,just those muffler eliminators, if you run the dual (X) pipes but I think many of us older guys will still find mufflers preferable.
http://www.ecklerscorvette.com/corv...less-steel-quad-zr1-style-tips-1984-1991.html It has a nice rumble at idle.
25-11310.jpg

the C4 corvette with an engine that is designed to exceed 450hp will require a low restriction exhaust, it would generally help to have long tube headers and a 3" dual exhaust with (X) pipes behind those header collectors and dual 3" inlet mufflers would in most cases help power output over the OEM exhaust design
INSTALLING AN (X) PIPE IN THE EXHAUST ON A DUAL EXHAUST CAR

http://pypesexhaust.com/p-13194-dyno-tests.html







Hot rod (oct. 2000)


355 SBC
9:1
trickflow alum heads
2.02''/1.06'' valves
comp magnum 286 hyd. cam (236/236 deg @ .050'', .490''/.490'' lift, 110 lsa)
edelbrock performer rpm intake
demon 750 cfm carb
3'' dual pipes
flowmaster "big block" mufflers
hooker 1-5/8'' long tube headers

Headers Headers with X-pipe
RPM HP TQ RPM HP TQ HP gain TQ gain

3000 219.8 384.7 3000 231.2 404.7 11.4 20.0
3100 224.5 380.4 3100 235.3 398.7 10.8 18.3
3200 229.7 377.0 3200 242.6 398.2 12.9 21.2
3300 234.6 373.4 3300 252.0 401.0 17.4 27.6
3400 240.1 370.9 3400 262.1 404.9 22.0 34.0
3500 246.5 370.0 3500 271.2 406.9 24.7 36.9
3600 255.5 372.8 3600 280.5 409.3 25.0 36.5
3700 269.1 381.9 3700 290.3 412.1 21.2 30.2
3800 283.8 392.3 3800 300.3 415.0 16.5 22.7
3900 295.5 397.9 3900 308.6 415.6 13.1 17.7
4000 307.6 403.9 4000 317.4 416.7 9.8 12.8
4100 320.7 410.8 4100 326.9 418.8 6.2 8.0
4200 332.6 415.9 4200 337.0 421.4 4.4 5.5
4300 343.5 419.5 4300 345.7 422.2 2.2 2.7
4400 351.8 419.9 4400 352.9 421.2 1.1 1.3
4500 358.7 418.7 4500 358.7 418.7 0 0
4600 362.5 413.9 4600 363.7 415.2 1.2 1.3
4700 367.1 410.3 4700 369.5 412.9 2.4 2.6
4800 371.2 406.2 4800 375.8 411.1 4.6 4.9
4900 374.8 401.7 4900 380.1 407.4 5.3 5.7
5000 376.7 395.7 5000 381.8 401.1 5.1 5.4
5100 378.2 389.5 5100 381.1 392.5 2.9 3.0
5200 380.8 384.6 5200 381.5 385.3 0.7 0.7
5300 383.8 380.4 5300 384.0 380.5 0.2 0.1
5400 387.0 376.4 5400 387.7 377.0 0.7 1.4
5500 390.0 372.4 5500 391.9 374.3 1.9 1.9
5600 394.8 370.3 5600 395.6 371.0 0.8 0.7
5700 397.2 366.0 5700 400.0 368.6 2.8 2.6
5800 397.1 359.6 5800 402.9 364.9 5.8 5.3
5900 393.3 350.1 5900 401.2 357.2 7.9 7.1
6000 388.0 339.6 6000 394.8 345.6 6.8 6.0



peak HP gain 25.0 @ 3600 rpm
peak TQ gain 36.9 @ 3500 rpm

AVG. HP from 3000-6000 rpm 7.99
AVG. TQ from 3000-6000 rpm 11.1

AVG. HP from 3000-4500 rpm 25.8
AVG. TQ from 3000-4500 rpm 17.2
71RS/SS396
RELATED INFO

viewtopic.php?f=56&t=1503

viewtopic.php?f=2&t=9827&hilit=mufflers

viewtopic.php?f=80&t=10730&p=46843#p46843
 
Last edited by a moderator:
http://www.melrosecorvette.com/1984...er-system-no-egr-no-air-add-catalytic-option/
one of the better current c4 corvette exhaust system designs is made by www.melrosecorvette.com
The melrose exhaust is a very well designed system, and keep in mind the exhaust gasses travel to the rear and pass through the (X) pipe they dissipate HEAT and loose some pressure and volume as a result, the (X) tends to mellow the growl slightly also, thus the two exhaust pipes past the (X) pipe share the split flow ,thats now sharing twice the original exhaust cross sectional area, at a reduced restriction, if I had the cash available thats the route ID suggest going , then you just need a decent quality, low flow restriction set of mufflers, added to the exhaust
one of the better current c4 corvette exhaust system designs is made by www.melrosecorvette.com



two stainless mufflers similar in design to this with a 3" inlet and dual 2.5" outlets seem to match the application, but measure very carefully after the exhaust is installed to verify you have the required clearance to mount and correctly connect them of course, before ordering
http://www.jegs.com/i/Flowmaster/389/80430402/10002/-1?parentProductId=1030933

vettemuffp.png


reading through these links, and sub links related to basic engine building will be useful, if your thinking of getting into a major engine rebuild

grumpy, who makes a really good quality header for my car?


I get similar questions all the time, and there ARE certain brands that do have a reputation for better fit and finish on headers,
but your results are totally dependent on you doing accurate ,prior research, your asking the correct questions,
knowing exactly what cylinder heads your using,and yes better quality tends to cost more than bargain basement prices!
knowing exactly what car it will be installed into and if your dealing with a better quality manufacturer helps.

http://www.superchevy.com/how-to/148-0404-best-headers-shootout/

http://www.lemonsheaders.com/

http://www.stahlheaders.com/

http://www.stainlessheaders.com/

http://stainlessworks.net/products/performance-systems/headers

http://www.burnsstainless.com/

https://www.carid.com/performance-headers.html




http://garage.grumpysperformance.co...pans-that-fit-the-c4-corvette.3071/#post-8131

http://www.ebay.com/itm/Chevy-Small...ash=item5888ff955f:g:mm4AAOSwDN1USU-o&vxp=mtr

http://forum.grumpysperformance.com/viewtopic.php?f=54&t=206&p=390&hilit=+seal+thick+pan#p390

http://garage.grumpysperformance.co...s-on-building-a-383-sbc-stroker.428/#post-524

http://garage.grumpysperformance.com/index.php?threads/oil-system-mods-that-help.2187/

http://garage.grumpysperformance.com/index.php?threads/building-a-custom-wet-sump-oil-pan.65/

http://garage.grumpysperformance.com/index.php?threads/whats-a-windage-tray-do.64/

http://garage.grumpysperformance.co...alling-connecting-rods-pistons.247/#post-1745
 
Last edited by a moderator:
Grumpy, I want to make sure my corvette engine lasts awhile and has zero problems , and I see conflicting info on the headers, cams oil pans rear gears etc., any input here might be useful?


Without getting into specifics youll generally want a low restriction exhaust , an enhanced cooling and lubrication system, and youll want to carefully match the cam timing engine size and drive train gearing to the intended application, and most newer guys to this engine building hobby, tend to over cam, the cars, while not looking into the correct matching drive train, gearing converter stall speeds, engine lubrication, oil cooling and low restriction exhaust components that are critical to long term durability.
adding an effective oil cooler and transmission cooler can go a long way to increase your cars drive train and engine durability.
use of a 7-8 quart baffled road race style oil pan with a windage tray, and the longer high quality oil filters with a high quality synthetic oil and fairly consistent regular oil and filter changes will significantly help long term durability.
theres two areas in engine building I constantly see either being ignored or where guys think that taking parts out of the box and bolting on a few components with little or no understanding of how they function, how they must be fitted, clearanced or selected to match other components or how the other components must be carefully matched to allow those parts to function correctly, makes the use of the parts or lack of proper installation either nearly useless or a waste of time and effort due to a near total lack of understanding of how the parts are intended to work.


read the links
http://garage.grumpysperformance.co...at-manifold-air-temp-sensor.10349/#post-42530

http://garage.grumpysperformance.co...elay-switch-locations-and-info.728/#post-9217


that's the full concept of effective exhaust scavenging, of the engines cylinders,which includes matching the headers,exhaust system and engine displacement cam timing and compression to the intake and intended drive train gearing so everything matches the intended rpm and power band.

in the ideal exhaust system youll want to have less than .5
(thats 1/2 a PSI of back pressure) at the engines peak rpm

expsize.png


exarea.gif

http://www.exhaustvideos.com/faq/how-to-calculate-muffler-size-pipe-diameter/

http://www.mk5cortinaestate.co.uk/calculator5.php

fe008cfd.gif

3" o.d = 2.87" diam. inside--approximately 6.5 sq inches of area
2.75 o.d = 2.62"diam. inside--approximately 5.4 sq inches of area
2.5 o.d = 2.37" diam. inside--approximately 4.4 sq inches of area
2.25 o.d = 2.12" diam. inside--approximately 3.5 sq inches of area

pipechart.gif


expipesz.jpg

well worth reading

http://www.popularhotrodding.com/engine ... ndex1.html


http://garage.grumpysperformance.com/index.php?threads/exhaust-components.361/

0505phr_exh_12_z.jpg


tubingsizeversusarea1.jpg

http://garage.grumpysperformance.com/index.php?threads/calculating-required-exhaust-pipe-size.11552/

http://garage.grumpysperformance.co...-exhaust-pipe-diam-for-your-application.1730/

http://garage.grumpysperformance.com/index.php?threads/is-backpressure-hurting-your-combo.495/

http://garage.grumpysperformance.com/index.php?threads/building-an-exhaust-system-for-your-car.1166/

http://garage.grumpysperformance.co...-calculators-and-basic-math.10705/#post-72061

http://www.wallaceracing.com/Calculators.htm
http://garage.grumpysperformance.com/index.php?threads/is-backpressure-hurting-your-combo.495/

http://garage.grumpysperformance.co...-between-shorty-and-full-length-headers.1303/

http://garage.grumpysperformance.com/index.php?threads/calculating-required-exhaust-pipe-size.11552/

http://garage.grumpysperformance.com/index.php?threads/calculating-header-design.185/

http://garage.grumpysperformance.co...-guys-that-just-slap-on-factory-headers.3155/

http://garage.grumpysperformance.com/index.php?threads/building-an-exhaust-system-for-your-car.1166/

http://garage.grumpysperformance.com/index.php?threads/anti-reversion-exhaust-design.789/

http://garage.grumpysperformance.co...hing-the-drive-train-to-the-engine-combo.741/

http://garage.grumpysperformance.co...-required-exhaust-pipe-size.11552/#post-59111

http://garage.grumpysperformance.co...lsa-effects-your-compression-torque-dcr.1070/

http://garage.grumpysperformance.com/index.php?threads/port-speeds-and-area.333/

http://garage.grumpysperformance.com/index.php?threads/valve-seat-angles-and-air-flow.8460/

http://garage.grumpysperformance.com/index.php?threads/more-port-flow-related-info.322/

http://garage.grumpysperformance.com/index.php?threads/calculating-overlap-and-lsa-or-lca-etc.480/
And
the effective use of,proper assembly and design of, and enhancements too the engines lubrication system to increase cooling and durability
the oil pan, oil pump, bearings clearances, shrapnel screens magnets windage trays,inertial oil flow control pan baffles
oil coolers oil pressure accumulators, and of course the lubricant oil selected.


http://garage.grumpysperformance.com/index.php?threads/oil-system-mods-that-help.2187/

http://garage.grumpysperformance.co...l-pumps-pressure-bye-pass-circuit-works.3536/

http://garage.grumpysperformance.com/index.php?threads/building-a-custom-wet-sump-oil-pan.65/

http://garage.grumpysperformance.com/index.php?threads/basic-info-on-your-v8-lube-system.52/

http://garage.grumpysperformance.com/index.php?threads/oil-accumulator.1280/

http://garage.grumpysperformance.com/index.php?threads/whats-a-windage-tray-do.64/

http://garage.grumpysperformance.com/index.php?threads/valve-spring-cooling-via-engine-oil.6491/

http://garage.grumpysperformance.co...m-oil-pump-installed-now-no-oil-pressure.525/

http://garage.grumpysperformance.com/index.php?threads/reducing-friction-and-pumping-losses.8966/

http://garage.grumpysperformance.com/index.php?threads/new-sbc-1980-85-oil-pan.6239/

http://garage.grumpysperformance.co...ans-cooler-on-a-c4-corvette.10514/#post-44498

http://garage.grumpysperformance.com/index.php?threads/l98-oil-cooler.10549/#post-44915

COOLING
http://garage.grumpysperformance.co...sion-and-oil-cooler-increases-durability.176/

http://garage.grumpysperformance.com/index.php?threads/how-the-cooling-system-works-basics.853/

http://garage.grumpysperformance.com/index.php?threads/cylinder-cooling-and-tuning-consistency.4701/

http://garage.grumpysperformance.co...ing-system-flow-rates-and-heat-transfer.9880/

http://garage.grumpysperformance.com/index.php?threads/copper-vs-aluminum-in-radiators.4230/

http://garage.grumpysperformance.com/index.php?threads/tips-on-cooling.199/
 
Last edited:
Back
Top