70 z w/sus - header or ex manifold??
01-14-2004, 10:46 AM
#1
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Join Date: Jan 2004
Location: Texas
Posts: 125
70 z w/sus - header or ex manifold??
On my previous Zs, I ran the 4bbl set up with a header. I'm currently building a 70 model and have been told that running the stock - boat anchor - exhaust manifold would work well with the SUs. My 70 Z will be running a brand new L24 , topped off with an E88 head. The head will probably be stock (still pondering what to do there). The exhaust manifold suggestion goes against everything I've always believed (headers having more flow - lighter - etc.), but thought I'd float it to see how you Z nuts feel.
What do ya'll think??
What do ya'll think??
01-14-2004, 03:51 PM
#3
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i dont understand either, use the header.i recently installed a trimil header with jet-hot coating,there is no way i would even think about going back to the stock manifold. i cant believe how much cooler the engine feels, there is almost no raidient heat comming from the exhaust. i have not driven the car for about 1 year for other reasons i wont mention,but i plan to take it out to the msa west coast nationals in april. i go down to the garage just to look at it, man that nickel coating looks awsome.and the build quality is very good, i installed it in the dark with no problems.i'll bet those who dont like headers never drove a small block chevy.
01-15-2004, 01:17 PM
#4
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Posts: 125
Look here
Thanks for the advice - I think I'm going with the 6 to 1 header (mainly cuz I have one).
Check out what I found. Read below.
HEADER
- The stock Z exhaust manifold is said to actually flow pretty well for the street.
- A header allows better top-end breathing by providing better "scavanging" of the gases from the exhaust ports, with gas mileage usually going up. The standard improvement advertised by header companies on most motors is advertised at 5-15hp.
I remember reading years ago that the Corvette 427 L88 motor would pick up 150hp just by adding headers. And anyone one who's ever modified a motorcyle can tell you how much of a difference a tuned header makes to increase performance. While a Z engine in stock form likely would see no difference, a L28 with a bigger cam, higher compression and ported head could really utilize one. Every road-race car in the world uses headers...good enough for me.
I've only tried one header brand so far: Motorsport Auto. The welding inside the collector was pretty poor, and the fiber gasket they provide doesn't last very long. Still though, it's worked fine for me with no problems. I think Thunderbird, Monza and Pacesetter are the only other companies that still make them for Zcars. So if you find a mailorder company that has a "noname" header, I would bet it's one of those. 6-1 or 6-2 collector? Supposedly one is better for torque, one for horsepower, I don't think it makes any difference. I like the 6-2 because fabricating the exhaust is easier. Buy whichever feels comfortable to you.
If you plan on keeping your Z for another 20 years, I would make sure you have an extra stock exhaust manifold in the garage as a replacement. I suspect Z headers will be difficult to find in the coming years as these cars get really old. Also, if you stay with the stock manifold, I would exhange the stock 240Z manifold with a square port '75-76 for street performance
Check out what I found. Read below.
HEADER
- The stock Z exhaust manifold is said to actually flow pretty well for the street.
- A header allows better top-end breathing by providing better "scavanging" of the gases from the exhaust ports, with gas mileage usually going up. The standard improvement advertised by header companies on most motors is advertised at 5-15hp.
I remember reading years ago that the Corvette 427 L88 motor would pick up 150hp just by adding headers. And anyone one who's ever modified a motorcyle can tell you how much of a difference a tuned header makes to increase performance. While a Z engine in stock form likely would see no difference, a L28 with a bigger cam, higher compression and ported head could really utilize one. Every road-race car in the world uses headers...good enough for me.
I've only tried one header brand so far: Motorsport Auto. The welding inside the collector was pretty poor, and the fiber gasket they provide doesn't last very long. Still though, it's worked fine for me with no problems. I think Thunderbird, Monza and Pacesetter are the only other companies that still make them for Zcars. So if you find a mailorder company that has a "noname" header, I would bet it's one of those. 6-1 or 6-2 collector? Supposedly one is better for torque, one for horsepower, I don't think it makes any difference. I like the 6-2 because fabricating the exhaust is easier. Buy whichever feels comfortable to you.
If you plan on keeping your Z for another 20 years, I would make sure you have an extra stock exhaust manifold in the garage as a replacement. I suspect Z headers will be difficult to find in the coming years as these cars get really old. Also, if you stay with the stock manifold, I would exhange the stock 240Z manifold with a square port '75-76 for street performance
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