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Headers vs. manifold

That drop for the DS is stainless, I have sat the truck down on that pipe and you can see where its bend.. I cannot bend this with a small sledge.. the pipe deformed a little but for a prefabbed part thats mandrel and for the price I couldnt pass it up. Ill buy another if I crack this one. I like how the other pic is but those headers are shorter as you said.
I had a 72 with hooker comps and basically the same setup motor wise and it made less low end power. Im sticking with my thorleys they seem to work.
 
Those are Hedman 69830's. I'd say if anything they are mid-length's. They do not appear to be as short overall as the standard "shorties" people talk about. I'm sure the pipes are shorter, but I think they also shortened the collectors a fair bit, and you can work around that if desired. Since they don't drop as far, they tend to clear shackles better than longer ones.

Just because they are long tubes does not mean they make more torque. 1-5/8 primary is already oversized for a mild 350 at low RPM's (which will hurt low end), a shorter header with 1-1/2" primaries would very likely make the same power down low than a longer header at 1-5/8". Unfortunately not aware of any headers that fit like the 69830's but 1-1/2", but if there were I'd probably buy them vs. the 69830.
 
While I do not disagree with your claim about pipe diameter, the tri y is designed to scavenge at lower rpm so were almost comparing apples to oranges, Plus the fact that we are not discussing the fact that I have a cat plus a large muffler which both add back pressure could make the difference up. I also dont know that a smaller diameter header with shorter primaries would make the same power, maybee at the rpm ranges your talking about but overall you would still sacrifice power somewhere.

The key that I have learned is to match it all, this is induction and exhaust all need to match for it to work. the issue being the advertised ranges are what you have to work with. in my case the intake rpm air gap is 15-6500 i have a larger carb 700cfm, my headers are larger primaries 1 5/8, exhaust is 3 inch next is cam that matches the rest. this will net you a better overall performing motor. Dont forget about the converter, its the second most important thing in the package, you want to get the motor in the tq range quickly as possible without destroying street ability. I used a 2200 stall in my 72 and that was fantastic for the combination. I may go to a 2600 for this setup because I wont be towing. One note if you think 2600 is high gm used that stock for a 6.0 ls 2500hd because the 4l80 first gear is to high for the smaller 6.0... intresting huh?
 
I'm not arguing for or against the Tri-Y's at all, just in general shorter vs. longer. Are Tri-Y's available in a length that will allow what Mastiff wants to accomplish? I wouldn't say no way to them, if they allow him to go over the front shaft, then go with them.

All conventional exhaust is a compromise, really have to pick your poison. Is upper or lower end where you want your power? You can't have both (in our case) although variable exhaust is apparently out there, just not applicable for this.

For *my* purposes I'd choose low end over upper end because that is where the engine makes it's power. As you mention, you need to look at it as a system. For a mild 350 with a mild cam and stock heads, trying for upper-end power via exhaust is counterproductive, but if you have an engine built to make power at a higher RPM, it makes far more sense to optimize exhaust for where the engine makes it's power.
 
a long tube with the right primary size for the mill will out perform those hedmans across the board...
 
No question there. Longer is always better if looking solely at performance.

No choice if you need shorter though, all you can do is optimize for your application, and choose whether you need low or high end power based on tube size.

AFAIK though, the Hedman's linked are about all that we know of that clears essentially every drivetrain combination in these trucks.

Edit: Don't want to add another post that people have to work at, but if anyone wants to compare the hedmans, go to schucks.com (yeah yeah, it's oreillys now) and type in 69830, click on the header link then click on the pic. In another tab open up shucks.com again, and type in 69890, which is the long tube they say is for our trucks. Look same pic up, and compare. Obviously shorter, but it appears to me Hedman tried to get as much length as they could out of the pipes on the 69830 in a more compact package.
 
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I always assumed the thorleys where VERY similar in their output to those.. just had the funky tri-y primary thing going on... in other words, you would never have shackle issues with a tri-y...
 
ryoken said:
I always assumed the thorleys where VERY similar in their output to those.. just had the funky tri-y primary thing going on... in other words, you would never have shackle issues with a tri-y...
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My tri-y's are very close to the shackle. They will probably hit on hard compression, though not enough to damage anything. I could grind away a bit of flange and be okay.
 
Mine have rubbed the flange, I reversed the bolts and ground down some of the flange. I may change the flange anyway at some point..
 
Well if you want to move away from Thorleys, I'm probably interested in them.
 
sreidmx said:
fea11f951998b7c1a401482d20a99af9.jpg
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O god :eek1:. No offense but thats horrible.




I love me my headers but that being said sometimes, especially on an offroader, packaging is more important that squeezing every horsepower out of it. The best manifolds to be had are old school ramshorns from SBC vettes.

Honestly a pair of flipped block huggers can get your exhaust running forward, and wrapped under the oil pan up front, then merged on the passenger side before you even get behind the motor. Its how all the KOH/Ultra4 cars package their front engine exhausts.
 
Mastiff said:
How would you route your pipes?
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But if I tell you, I'll miss out on a good deal :confused:.

I had true duals, then switched to a single muffler with dual in/out. So there is a pipe on both sides of the transfer case, then it crosses over behind the T-case. It is pretty tight between the NP208 and frame on the PS with the 2.5" pipe, so it is actually flattened just a little in that section.

PICT0256.jpg
 
Blue85 said:
But if I tell you, I'll miss out on a good deal :confused:.
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Ha. Yeah, I've considered that approach but I'd have to redo my fuel lines a bit.

Honestly, I don't care about performance that much. It's tempting to get some manifolds, put a good coating on them and be done with it. A bonus would be having the O2 sensor up where it should be. The bung on the Thorley's is far down and I've never been totally confident it's staying hot enough.
 
it should be a 3, or 4 wire heated one....if it's not heated, you very well could be having issues..
 
Run duals past the transfer case. You can male a heat shield for your fuel lines.

Martin
 
ryoken said:
it should be a 3, or 4 wire heated one....if it's not heated, you very well could be having issues..
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Yeah, it's a 3-wire heated. It's probably okay, I'm just paranoid since I went through so much trouble with that TBI conversion.
 
Stomis said:
O god :eek1:. No offense but thats horrible.




I love me my headers but that being said sometimes, especially on an offroader, packaging is more important that squeezing every horsepower out of it. The best manifolds to be had are old school ramshorns from SBC vettes.

Honestly a pair of flipped block huggers can get your exhaust running forward, and wrapped under the oil pan up front, then merged on the passenger side before you even get behind the motor. Its how all the KOH/Ultra4 cars package their front engine exhausts.
Click to expand...


I agree its a terrible design, however its stood up to my abuse.. I have to imagine its pretty thick pipe, it does kill my clearance, when it cracks maybee Ill reroute it.. For a trail truck that doesnt go crawling much or sand its fine.
 
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