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I think I'm down to the final couple hurdles in this LS swap and could use a hand if anyone is familiar with different headers. In a DeLorean so space is at a premium. These are the stock manifolds for a 2005 L33 Silverado 5.3. The LH side could actually be fairly close, except the 3 bolt flange hits the chassis, so the manifolds can't press up against the heads. Same issue on the RH side, although it seems to be tighter (manifolds are asymmetrical so that side seems larger). Hard to get a wide angle photo, I'll try again tomorrow.
The 3 bolt flange style definitely seems to be a problem. (I was only trying these manifolds out since they came with the engine). My first thought was a turbo-style header that goes straight back (or forward in this case) but as you can see in the first photo, I need to go 90 degree down before the axle shafts, so some downward angle may be good. Additionally, turbo headers seem to be 3", which is far too large.
Looking at photos, GTO headers seem to go too low to clear the DeLorean crossmember. Corvette seems to exit too downward as well.
Something with this truck angle, but closer to the block, and a smaller flange would probably fit the bill. Any suggestions?
(Hard to see in the photos, but I think if the manifold could get closer to the head, the 3 bolt flange would stick out even farther, making the below style fit even less.
I think I know the cons about the below Speed Engineering swap headers (block interference at the starter, I need to look at my car and see what I have going on there. https://www.ebay.ca/itm/274322690405...gAAOSwb69Z1slz
There is also this similar Chinese brand (same brand? Different name? Who knows), which I am wondering if they come out of the same factory, except these have 3 bolt flanges vs v-band clamps. I particularly like the 'graphics' that show the air going the incorrect way.
Probably close to around stock (310hp I believe in the L33?). Maybe a cam in the future. Nothing major. Much more concerned about fitment than power in this car. I see with some reviews of the "Speed Engineering" headers, some guys mentioned they hit a boss on the block. Anyone familiar?
Roger that, the reason I asked is that if you're just looking at a stock-ish build, why even dink around with headers at all? Iron manifolds will likely fit way better, be cheaper, quieter, and be overall less of a headache.
Unfortunately the stock truck manifolds i have don't fit (first post, all manner of flange interference with the chassis). Maybe there are some other ones that do fit better (Trailblazer/Envoy??) but I don't have at my disposal unfortunately (nor is Kijji offering up any deals). The reason I feel like I can be a bit riskier with cheap headers (mild or SS), is I could reweld the steel ones if need be. Am I thinking off-base here? I'd be all in with stock manifolds that fit though!
(Those second ebay headers I listed are about half the price of the first ones, but have a 3 bolt flange instead of a V-band.. Kind of deters me. Plus, they can't be bothered to clean up the sooty welds for ebay photos??)
If stock manifolds don't fit, how are headers going to? I just did some cursory googling and it looks like guys have build their own headers from a tubing kit.
I wouldn't' buy anything "brand new" on ebay if my life depended on it, just not worth it. Watched too many guys buy fake garbage and then just have to go buy the right stuff in the end.
Last edited by theunderlord; May 23, 2022 at 01:32 PM.
Reason: removed link to crazy persons company. :D
I suspect the Summit ones are made by Patriot, since Patriots are the only ones I can find that have the ball and socket flange, and the collector with an O2 bung.
I live up north in Commieville, I suspect both policies blow. Summit isn't too bad, I have to ship it locally to a Fedex depot, and they take it from there (I think they must wait, then ship them all back via a Fedex truck at once). But you still lose out then on the shipping and tax that you originally paid ($100 in this case). Jegs, it looks like you have to ship it all the way. I have never dealt with a return to Jegs. The purchased I have made, haven't been fantastic either (I get the parts in the end, it just takes much longer). I suppose I need to convince myself the ball and socket and o2 bungs are worth the $100?
Canada! ahh, got it. Yeah shippings a bitch up there. I used to have guys in my old car club come down from Vancouver and pick up all the stuff they bought and had shipped to my machine shop.
50 bucks a side for 02 sensors and adapters, might be worth is, less work later?
Well, I used to call it Canada. Not anymore! (I also used to ship to Buffalo, but don't have enough time to do that anymore. Would only be an hour if not for the crossing). I will probably agree with you on this front too.
(Look at that, I've gone from nice stainless headers, to rusty cast manifolds because of your input!
I wish they would publish an estimated max (potential) horsepower though!
Those stock manifolds can support quite a bit. I mostly hack them up and use them for boost, but they don't slow the flow down to a turbo, so I'd guess they will support 500.
On another note, if you have the equipment, you can pretty easily cut and weld on those. The material they cast them out of, is very acceptable to modifications without much issues.
If the manifolds work except for the flanges, why don't you cut the 3 bolt flange off and weld on a v band. Turbo guys do it all the time.
X2
I modified a truck manifold by cutting it along the sharpie lines and welding on a section of schedule 40 pipe. You can eliminate the kickout and add another turn down with a V-band in an area with better clearance.
Last edited by fieroguru; Jun 5, 2022 at 08:03 AM.
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Header selection help for swap. Tight clearance 
I just did some cursory googling and it looks like guys have build their own headers from a tubing kit. 
does one or the other have a better return policy in case there's fitment issues? 
