I have 2 sets of headers that I can install on my car and would like your input on which set I should go with as I would really like to maximize performance but am not sure on which set to use based on my dyno chart and my goal.

This ios a 69 L46 motor rebuilt with 9~9.5:1 about 10,000 miles ago and performance intake and some other goodies. Currently has block hugger headers with a 2.5" straight pipe older somewhat rusty through flowmasters.

Header #1
Hedman #68300
1 5/8" Primary Tubes
16 guage
1/4" flange
Benefits I see is that the tubes are thicker 16 guague and are 1 5/8" so I should not loose any torque, but they are not equal length and have a nasty 90* bend in them.

Header #2
Hooker Super Comp #2134
1 3/4" Primary Tubes
18 guage
5/16" flange
Benefits I see are the tubes are very close to equal length (I measured with filling them up with water and then comparing the difference in water volume needed) and have more smooth bends, but the tubes have thinner walls and are larger 1 3/4".

Also going with the header install at the same time will be a complete Magnaflow muffler & x-pipe system all 2.5" mandrell bent.

I am not worried so much about low end power below say 2,500 rpms because I have maximized my gearing to compensate as the car now has a 6 speed ROD with a 3.70 rearend with a torque multiplication ratio of 11.137 for first gear. I am more concerned about hp/ft lbs. around the 2,500 to 6,000rpm range.

I am trying to weigh the benefits I guess of smaller tubes with 90* bend vs. larger tubes with a more smooth bend.

Which do you all think I should go with based on my dyno chart and where I want to maximize my HP in my rpm range?

 

I really have no idea but based on the priciple of you get what you pay for, I would go with the Hookers.

I am looking at exhausts at the moment and nearly everyone has advised me to go with the Hookers. They seem to be one of the top after market manufacturers.

 

bump??? I have appointment scheduled for Monday & Tuesady to have the exhaust shop do the work so I would like to know what you all think. Will I loose any HP going to the 1 3/4" headers that are more free flowing or should I stick with the smaller 1 5/8" with a harsh 90* bend?

 

With the 350 motor and some mild perfromance you would be fine with the 1 5/8 headers. When you start getting up in cubic inches or start turning a lot of rpms then you might be better off with the 1 3/4. I just switched out the 1 5/8 on my 350 which I ran to 6500+ rpm a lot. I put on the 1 3/4 Hookers with a 385 ci SB and it turns 7000 rpm. The HP difference between the two dofferent headers in your case would be very small. The 1 5/8 fit my car better also.

 

You've only got 183hp? Shoot, my L81 had that much with the stock exhaust...

Oh, and I personally went with the best deal I could find on headers. Summit long tubes. They're probably made by either hooker or hedman but they're sold under the summit name for $75 now.

 

It would be nice if they are coated. Larry

 

Didn't mention wanting a coating... I figure for what it's worth I could buy 5 sets of headers for as much as the coating costs.

 

I was referring to the original post, but I have to agree..... they do really like that coating. I couldn't swing it....I bought regular Hedman. Larry

 

Well....the dyno is known to not be the at all generous in HP numbers, but even factoring this in the figures are still a bit lower than I had expected although the car does accelerate much more quickly than the dyno number would suggest as the torque multiplication factors have been maxed out through the 6 speed and rearend combo. We will see how it does at the Corvette Challenger Series @ Moroso on Aug 2nd. I just finally got the car back out of the shop a couple days ago with the new 6 speed installed and so I am enjoying it for now, but within a year I will be pulling the numbers matching engine and dropping in a new GM crate Hot Cam 400+hp small block which will definitely get me some nice 1/4 ET's.

Anyway...The Hedmans are chrome or ceramic coated (look really nice and shinny) and the Hooker are just plain normal painted if this helps at all. I am leaning more towards the Hedmans right now since I am not putting down that much HP, but I was still surprised to see 260 ft lbs so I am somewhat hesitant to go with the smaller diameter 1 5/8" in fears that I will kill the 260 ft lbs to even a lesser number.

 

The bigger diameter won't help your torque, let me tell you that right off the bat. You have to pushing AT LEAST 400hp to need 1 3/4"

Like I said, my L81 with a mild cam, long tubes, sidepipes, HEI, and normal q-jet is putting down more power than that.

 

Hi Rob..I bet You been out enjoying the new 6speed

I think Id be considering matching a new "header & muffler" setup to the new 400hp engine youll be getting soon. Looks like the engine you have in now is low power but valuable because its number matching , so just leave it intact and pull your present exhaust, store it, and choose the new system to go with your future 400hp engine, That way you wont have to rebuy the exhaust, you wont be seeing any significant difference on your present engine anyway. The 1 5/8" primaries is plenty good for your future 400 HP+ motor too.
Also..
You mentioned your not concerned much about low end torque with your new gearing, Let me point out that your overdrive gear will be pretty dead if theres no low torque available when you shift to 6th. Im not saying thats a problem, in fact its not. All it means is if you dont have low end torque your car will excelerate "Real slowly" in 6th till you get up to maybe 80+ then the overdrive gear will be under power again and will pull hard to maybe 130-140 or wherever 6000rpms is without over reving. This was the case with my .62 overdrive gear. Doesnt make much difference now, but its good to know, makes choosing what cam and what intake port size for the new heads a little easier in the future. Just thought Id mention it, Im having the same considerations ever since installing the ROD.

Tom

 

Thanks for the suggestions guys. I finally got my new exhaust system done and it came out awesome. I ended up going with the Hedman Ceramic/Chrome looking (Polished inside & out) headers vs. the Hooker Super Comps as the Heman were brand new with a nice chrome/ceramic finish inside & out to give the car a little more shine in the engine compartment and I did not want to deal with loosing HP from going with the larger Hooker's and any fitment issues. We also went with a full 2.5" mandrel bent exhaust with x-pipe and magnaflow mufflers. I previously had a very old set of block hugger headers and a 2.5" pre-fabbed exhaust (not mandrel bent) that was all clamped together finishing off with a set of flowmasters. I took the car to a place called Miami Muffler located in South Miami and they are the only ones in the state that have a mandrel bending machine. The old exhaust system had some really nasty flow restriction bends from not being mandrel bent and was just 2 straight pipes. I am very surprised to feel a difference in power. The car really moves nicely now and I am now spinning the rear wheels much easier. I have to re-learn how to take off from a light without spinning the wheels as all the way home I was having trouble launching the car without spinning the wheels unlike before where I had it done on how to luanch without spinning. I hope to get a dyno run done (August 11th) by the same shop that did my last dyno run up in Orlando so we can get a direct comparison of the difference. I have a few logistics to work out but I should be passing through Orlando from Miami with the car so it would be cool to see a back to back comparison. Also for the sound of the car I really like it a lot. The idle is about the same with a nice rumble, cruising now at any speed I can barely hear the exhaust (no dronning, just a sweet subtle little note coming from the rear at the most if you strain to listen for it), and now at wide open throttle (WOT) I have a nice smooth roar coming out the back end. Everybody now says it sounds like a vette should be being smooth letting others know I mean business, but not obnoxious. Before when I was at WOT it was extremely loud and also there was a constant roar/dronning sound while cruising with old system. I will try to get some video clips and also pics in the next few weeks of the system for you all to hear as your guys input really helped me to make a good decision on my exhaust system from your pics and video clips and hope my pics and video clips can do the same for others.

Cheers....

 

I have modified hedman and hooker headers and found the hooker far superior in quality. Unless you are buying the hedman elite headers hedman uses 18 gage material, not 16 gage in the normal headers. Hooker uses the 16 gage in the super comps.
Hedman makes a good cheap header but hookers are better quality.
This does not apply to the hedman elite.

 

These were the headers that I am using Hedman 68300 and use the thicker 16 guage. I got them from the previous owner of my car who never installed them. He bought them with either a highly polished ceramic coating or chromed (obvisiously I am not an expert here in the stuff) with them being coated both inside and out making them really shinny and smooth.

http://store.summitracing.com/partde...5&autoview=sku

The other pair of headers headers that I had to install were a used set of Hooker Super Comps #2134 being only painted (not ceramic coated) and have the thinner 18 guage pipes. So now that I am satisfied with my current setup I will be selling theh Hooker here shortly after I take a few pics of them.