To sidepipe, or not to sidepipe.. That is the question.

pancake said:

The pace car spoiler i am going to put on will not help ground clearance, either. Besides, the pipes are very close to the ground now where they cross under the diff.

Sbg- do you have any pics of how you wrapped your pipes to prevent heat transfer to the sewer pipe? I am assuming you just wrapped the collector?

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this is the muffler I wrapped.... don't think I actually took a picture of it wrapped. The wrap is actually sitting behind the mufflers in this picture. It was wrapped around the outside of the muffler, not the collector


I didn't care about the collector because my leg would never be close to it while exiting the car.

mrvette said:

Some years ago I got on the phone with the owner of Schoenfeld Headers in Arkansas I think....we got to discussing a set of 151 Chassis headers he made for SBC, happen to fit my car just perfect with the rack steering, and the collectors are higher than the oil pan, and clear the filter/starter just fine.....

they are unequal length headers, I questioned that, and his comment was....'for some reason, cars like unequal length headers, and engines dyno better with equal length headers'......meaning the UNequal length headers give a less peaky torque curve,....makes sense to me....

and he went on to say that putting on any kind of exhaust pipe and especially ANY kind of muffler will totally negate any gain from the headers, in other words, they are a waste of time and money at that point.....

He could have lost a sale with that comment, but in fact for the 150 bux the headers cost me, at that time, they still on the car doing just fine....and my only issue was melting plug ends on #5&6 plugs, screw it, on with a set of Jacobs ceramic caps, melt THAT, bitch....

but that comment that adding ANY muffler and long pipe wipes out any header gain was somewhat surprising to me, but upon thinking about it, I suspect he is correct, but no one wants to admit it.....so a stock set of late 80's headers from GM would work as well, just remove the air pump crap....:tomato:

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close really counts when doing exhaust lengths - and you're right, building for max dyno power isn't the same as building for streetable power. I'm still not sold on the idea of peaky or not - with the numbers that are at issue, I'm not sure that anything other than a dyno would notice the 5 hp here, or the 10 hp there.... properly sized headers, all by themselves, get you 95% of the hp available - the rest is stuff that drive the circle track guys nuts (and NASCAR) but I'm not convinced it's relevant to a street car.

If I were driving my car long distances or often I would probably stay with a rear exit exhaust. I moved to side exhaust to make it easier to work out my rear a-arm suspension and allow me to lower the car for track days.

I run Sanderson cast iron headers into 3 inch pipe then 4 inch into Hooker sidepipe tubes. I picked up the tubes for $100 bucks for the pair. For mufflers I went with ones from Classic Chambered Exhaust. They had mufflers to slide in and their service was excellent. They also have side mufflers so you can run them without the Hooker sidepipe tubes.

Everytime I hear 'sidepipes', I think of this...

http://forums.corvetteforum.com/c3-...mount-headers-horrendous-product-quality.html
:ripoff:

pancake said:

Most of the resident guys over here have way more experience with hot rodding than I do so I want to pose the above question.. Is there a noticeable decrease in performance by adding side pipes vs. running an under car exhaust?

Here's my setup:
4 bolt main vortec 383, 10.75:1 compression, GMPP Fast Burn heads with 2.02 1.60 stainless valves, Howards single pattern hydraulic roller .560" lift 112 lsa..

I am running summit steel headers with 1 5/8" primaries, 3" collector.. and the 2.5" Corvette Central exhaust through magnacrap mufflers. My estimates show that I should step up to something with 1 7/8" primaries and 3" tubing...

Or I could be lazy and just order up a set of those chinese side pipes.

Any input?

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I don't have extensive dyno testing but I have some combined with G Tech data that has led me to conclude that for a small block with Hooker side exhaust the "sweet spot" is approximately 300-350 rwhp.

I was running a 383 with AFR 195 heads, 10:1 RPM Air Gap and Voodoo hyd flat tappet cam, duration @ .050 (Int/Exh): 233/241 .505" .525" lift on the dyno runs. On the street I had three different muffler/pipe combinations. Full 4" pipes with Cherry Bomb glass packs, three inch i.d. four inch o.d. generic glass packs and four inch o.d. auger style mufflers.

Using the G Tech data the performance was as expected. The slowest was the Cherry Bombs (quietest), the auger and large glass packs were pretty close.
On the chassis dyno I ran open and augers. The augers cost 7 HP and 20 ft-lbs over open. The open numbers were 327 RWHP and 380 ft-lbs.
None of the muffled options were quiet enough for my liking. The large glass packs and the augers were painful inside the car even without excessive pedal.
I switched to a larger solid roller cam (around 243-251 duration) and the results were not as great as I had hoped for. I put the engine in a Camaro with 1 ¾ Hooker Super Comp headers, 2 ½" full exhaust and the performance was better throughout the rev range. Both cars had 4:11 gears but the Camaro had a TK600 and the Vette had a T56.

Bottom line is I think with a lesser output engine the side exhaust will needlessly hurt low end and on higher HP it's choking the high end. But I found it hard to keep the noise down at these power levels.

Factory 69 Sidepipes on the 68. Hooker headers on the ex-69 BB. Planned for the 70 BB.

My main reason for going to sidepipes is principally to clean up the bottom of the car and reduce cabin heat.

The stock exhaust runs underneath the floor where the gas pedal is located; i.e. C3 hotfoot. Also, the stock exhaust buggers up working with the shift linkage and working on the rear end suspension. The stock exhaust heats up the tranny, the diff, and also cooks the rear spring...a problem with a composite rear spring.

My factory 69 sidepipe exhaust is much louder than stock. I've read that it's nevertheless more restrictive than the factory stock exhaust!! If so it's the worst of both worlds if reports are true...but it does look really cool!

I read the above linkage to Lar's experience with his Hooker headers. Very disappointing. I had Hookers on my 69, and there was a little fuss getting them to fit..dinging them to clear the steering box, they were otherwise OK. Very noisy and of course they tagged my girlfriend of the times lower leg a. ..only once though.

On my 68 and 69, with the factory exhaust converted to side pipes, I converted the rear exhaust panel to look just like a stock 69 with factory sidepipes. For my 70, I had an original rear exhaust panel for a 69 sidepipe car, converted over to 68 backup lights (original backup light fiberglass brackets).

I'm really disappointed the 69 factory sidepipes...according to what I've read, are more restrictive. Maybe some day I'll get a chance to dyno the car with and without.

LOL.... I also read Lar's product review..... :lol:

incl. the side tubes and heat shields I spent quiet a chunk of money and I probably also got the worst of all worlds: it's restrictive, it's loud.... but it sure looks and sounds cool

I've seen some muffler testing over the years. Funny that none of tjose "tests" show a close to stock or mildly modified 350..... most mufflers claim huge benefits on a 500hp engine.... no idea what the benefit on a 350hp engine is.... 15 hp maybe ??? I trade 15 hp for the "cool" look :trumpet::trumpet: