headers that work with sidepipes

[rlphvac]

do you know of a good set of headers that will work with hooker sidepipes on an81 vette with a HP 383 automatic

 

[grumpyvette]

I've been a fan of big block engines for decades and had a low 10 second 1968 corvette with a crower fuel injected 496 cubic inch big block engine with side exhaust,and a full roll cage.
the basic well proven fact is that almost all the commercial headers were and are designed with fit and ease of fabrication as the primary design parameters and max performance far down the list.
low cost and ease of manufacture , and designing a single header too fit as many applications as possible to simplify inventory issues, has almost always been the manufacturers goal.
longer primary tub length has frequently proven to provide both more mid rpm torque and more average torque, and its the torque within 2000-rpm-3000 -rpm of the peak torque that moves the car during almost all the time in performance use.
longer tubes cost more money and make the header harder to design too fit well, so most manufactures rather design a shorter headers that may fit several similar cars rather than the ideal longer header for a single application.

4 into two, into one collector designs (LIKE BELOW)have also proven to be excellent performers,
but the generally work best if the cam timing and high compression are well matched

one of the rather well established racer tricks has always been to run open collectors too reduce back pressure, as
( headers scavenge best, with zero back pressure)
and in many cases, where clearances allowed, we cut the collectors of commercial headers , and welded on pre made extensions
(LIKE THESE BELOW)and almost always saw a boost in performance

https://www.summitracing.com/parts/FLO-C134218234/

one reason side exhaust on corvettes were and are used is the design allowed decent ground clearance AND long efficient header primary tube header designs.

viewtopic.php?f=69&t=3814&p=43882&hilit=crower+corvette+1968#p43882

viewtopic.php?f=56&t=1730

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

USE THE CALCULATORS to match port size to intended rpm levels... but keep in mind valve lift and port flow limitations
http://www.wallaceracing.com/runnertorquecalc.php
http://www.wallaceracing.com/ca-calc.php
http://www.wallaceracing.com/area-under-curve.php
http://www.wallaceracing.com/chokepoint.php
http://www.wallaceracing.com/header_length.php
http://www.circletrack.com/enginetech/1 ... ch_engine/

http://www.pontiacracing.net/js_header_length1.htm

http://www.wallaceracing.com/header_length.php

http://www.wallaceracing.com/Calculators.htm

https://robrobinette.com/et.htm

https://www.gregraven.org/hotwater/calculators/qm-from-wt-hp.php

http://www.bgsoflex.com/auto.html

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

http://www.can-of-whoopass.com/index.php?pageID=car_stuff&calculator=primaries

I’m trying to decide if a 500HP/500Torque SBC crate engine is worth the expense ($8K – $10K).

Currently, I have a L-82 (4 speed) with Brodix IK180 heads, true dual exhaust with Stan’s Tri-Y headers, Lunati 60101 Cam and 3.73 gears.

I have no idea what my HP is today, but would I notice a big difference in buying a 500HP crate motor compared to what I have today?

If I still owned a C3 corvette, and had $10K or so to spend on a new engine, theres no question at all in my mind that Id have chrome side exhaust and a serious 496-572 big block engine installed in the engine compartment.
500hp SBC are about as common a mustangs and camaros with owners that think they own a fast car, you only live once, build something MEMORABLE and IMPRESSIVE!
I had a 1968 with a full roll cage a 496 BBC and a dana rear at one point and I had lot of memories made in that car, and while it was virtually useless, because any place I drove it I had to park it where I could watch it, and it seemed to attract a police car following it rather rapidly, as I had crower injection sticking out of the hood. it was still a real fun car to drive, as I could smoke street tires effortlessly even from a 60 mph roll.
http://www.herbertcams.com/dhp-555-street-chevrolet-big-block-engine-675hp/
crower mechanical stack injection.

Ive always like the look of corvettes with well designed a side exhaust
but they get a bad reputation from guys who have girl friends burn the back of their legs exiting the car on hot side pipes, or guys that insist on running extremely restrictive inserts to reduce the noise who then bitch about the resulting loss of power

if you can visualize a chrome bumper corvette similar to this picture with those stack injectors sticking thru the hood in a burgundy colored corvette with larger rear wheel flares a tubed rear with huge tires and a full roll cage you be visualizing something similar
Ive always just used the HOOKER or DOUGS side exit headers with the HOOKER or DOUGS side pipes, on my big block corvette,or other C3 corvettes I work on and Ive generally found side pipes provide the best power PROVIDED you fabricate a low restriction muffler insert rather than the factory inserts , and the reason was that the under the car clearance did not allow the use of a true dual 3" exhaust with adequate clearance, while side pipes use a free flow 4" collector which allows far less restriction. something any correctly set up big block you set up to breath would require! all the factory available muffler inserts are restrictive, so restrictive to flow that I've seen dyno tests where just removing the muffler insert in each side pipe was worth 60 plus peak horse power the real advantage of side pipes is that most factory headers have 26"-to_29" primary tubes to make the header fit easily in the area along side the engine, but if you understand the math of a tuned exhaust, it requires a 36"-40" primary pipe length to get the ideal cylinder scavenging, something that just happens to be similar to the length of pipe used in side exhaust set-ups, a properly set up side exhaust can be tuned to provide excellent results.
the muffler inserts vary a great deal in quality and how effective they are in reducing noise so you obviously have options, most of the factory inserts are far more concerned with noise reduction than maintaining peak power levels so I found I had to fabricate my own inserts.
what I eventually found, out was that I could custom fabricate (cut and weld) perforated steel sheet ,
https://www.onlinemetals.com/merchant.c ... &top_cat=1
into cones, similar to the expensive one pictured below and weld them spaced every 6" on a thread rod and make a baffle insert , for the side pipes that did not noticeably restrict flow, or power, but did reduced noise.

btw use poster board(CARD BOARD) and tape to make a pattern , to use before your cut perforated steel to make the cones, youll need a shape thats roughly triangular, the total open area of the holes in the perforated sheet exceed the surface area of the open 4" diam side pipe resulting in little if any restriction to flow

https://www.cmrp.com/cone-calculator

https://www.blocklayer.com/cone-patterns.aspx

http://craig-russell.co.uk/demos/cone_calculator/

http://theurbanfarmingguys.com/iFrameTest.htm

https://planetcalc.com/3831/

https://www.blocklayer.com/cone-patternseng.aspx

YOU MIGHT WANT TO READ THRU THESE LINKS
viewtopic.php?f=56&t=495

viewtopic.php?f=56&t=961

viewtopic.php?f=56&t=185

viewtopic.php?f=56&t=1166

viewtopic.php?f=56&t=7831

http://www.summitracing.com/parts/HOK-2224HKR/

http://www.summitracing.com/parts/HOK-2224-3HKR/

http://www.summitracing.com/parts/HOK-2233HKR/

http://www.summitracing.com/parts/HOK-2222-1HKR/

these muffler inserts below help reduce back-pressure, over many inserts, keep in mind that the efficiency of the headers scavenging the cylinders , and helping to draw in the following intake charge,is almost totally dependent on maintaining a very low flow restriction or back-pressure in the collectors ,especially at mid and upper rpm levels

VIDEO SIDE PIPES HOOKER INSERTS VS SPIRO INSERTS

http://www.spiralturbobaffles.com/

viewtopic.php?f=56&t=495

viewtopic.php?f=56&t=7831&p=27049&hilit=side+exhaust+dougs#p27049

these baffles above seem to work reasonably well but IVE always preferred building a custom set of baffles using perforated stainless, for all the internal baffle components on my corvettes

viewtopic.php?f=56&t=495

viewtopic.php?f=56&t=496

viewtopic.php?f=56&t=961

viewtopic.php?f=56&t=1166

viewtopic.php?f=44&t=1518&p=3473&hilit=preforated#p3473

viewtopic.php?f=56&t=1507&p=3617&hilit=baffles+exhaust#p3617

viewtopic.php?f=80&t=793&p=1150&hilit=baffles+exhaust#p1150

viewtopic.php?f=62&t=1518&hilit=perforated

 

[grumpyvette]

superpowers posted this

http://www.xs-power.com/corvette-headers-2.htm

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

Here is an "how to" guide for installing side pipes on your C3 corvette.

First though a quick review if I may.
I ordered these XS-Power sidepipes on Monday and they showed up on Friday, so I am very happy with the turn around. The packaging was exceptional, it took me over 10 minutes to get the stuff un- packed!

The pipes are mirror polished stainless steel. The welds are all tigged and they are very nice welds. The primaries are 1 7/8" into a 5" collector and then tapers down to 4" and the side pipes are 4".

The very first thing you need to do is disconnect the battery.

Jack the front of the car up and secure it on jack stands

Next remove the stock exhaust and headers from the car.

On the driver side. Remove the Z-bar if you have a manual transmission.

Un-plug the spark plug wires from the plugs, you can leave the plugs on, just be careful!

Install the side pipe header from the bottom of the car. I used a jack stand to hold the collector up while I bolted the header to the block.

Reinstall the Z-bar.

You can now put your plug wires on and re-install your spark plug looms if you have them.

Notice how nicely the pipes fit around the steering gear box.

They fit nice and tight to the frame. They have awesome ground clearance.

Now lets move onto the passenger side.

Remove the dipstick.

Un-plug the spark plug wires from the plugs, you can leave the plugs on, just be careful!

Install the side pipe header from the bottom of the car. Again I used a jack stand to hold the collector up while I bolted the header to the block.

Now re-install your plug wires and looms and you are ready to move to the pipes.

Slide the pipes over the collector and tighten the clamp on the pipe with the hardware that you bought at the store. You remembered to get hardware didn't you. :lookinup:

Mark the frame through the hole in the mounting tab welded onto the pipe. Drill the hole then thread the hole and screw in your fastener.

Guess what YOU ARE DONE. Go hook up your battery and then go out and scare your neighbors! :devil:

Here is a video of the newly installed sidepipes. The pipes are surprisingly mellow when the car is idling and even cruising. I could even hold a conversation without yelling. But when I opened it up...man did those pipes come alive. We also noticed the idle got alittle more lumpy. Must have been all of that extra air the car was able to shed because of the giant primaries.

The install took a couple hours and very few tools. The fit was great and the polished stainless looks awesome! And I saved a ton of money over the hookers.

My overall impression of these XS-Power sidepipes is: AWESOME!