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Thread: 1995 K1500 header install

  1. #1
    Fuel Injected! Roadknee's Avatar
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    1995 K1500 header install

    I’ve thought about headers off and on for about 5 years. After 20 years of use one of the OEM manifolds developed a crack so I decided to take the plunge. I don’t care much for the shorty headers that bolt in place of manifolds. For a compromise between fit and function I decided on a set of mid-length headers. I have a well-respected header design program called Pipemax. For a 5.7L engine making 300 hp at 4,800 rpm (my goal) it recommends 1.275” -1.4” I.D. primaries and a 2.5” OD collector. The big name offerings used 1-5/8” diameter 18 gauge tube which is both oversized and a little light for truck use. Some of them also have a poorly shaped 3” diameter collector. I came across L&L Products that manufactures their own line of headers in-house in Texas. They offer a header with 1-1/2” diameter 14 gauge (0.090" wall) primary tubes (1.320” I.D.) a 2-1/2” merge collector ½” thick flanges and a high temp nickel coating inside and out. The flange opening is about the same size and shape as a stock SBC exhaust port unlike many of the big name headers with a huge flange opening to accommodate big aftermarket performance heads.

    Bolting the headers on was pretty straight forward. L&L forgot to send the flange gaskets so I used a set of FelPro 1404s I had kicking around. I ended up deleting the alternator/power steering support bracket on the driver’s side for now. I’m looking at a way to modify and reinstall down the road when I do the engine swap. There is no provision for the hot air tube on the passenger side, which I’ll address before it gets cold. The headers arrived with a set of connecting pipes for twin cat vortec engines. I would have used them, but they were only 2” diameter. Instead, I purchased some 2.5” mandrel bends from Summit an O2 sensor bung and a new Walker cat, and a 2-2.5” into 1-3” merge collector from Cone Engineering to build a custom Y-pipe.

    I drove over to my dad’s with the open headers and connecting pipes installed. I had disconnected the O2 sensor and despite getting up to operating temp for several minutes the ECM never through a code. It took dad and I about 4 hours to fab up and install the Y-pipe. I’m pretty pleased with how it came out.

    With the headers installed the exhaust note is unchanged at idle and low cruising speeds. I don’t notice any header noise in the cab, probably due to the thickness of the tubes. It has a little deeper rumple when I lean into the throttle, which I like. The rest of the system is 3” single with the longest 7” diameter see-through Magnaflow muffler I could find. I’ve only driven around town so far so I can’t say if it makes any more power. Keep in mind right now I’m running a bone stock 165K mile L05.

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    Fuel Injected! brian617's Avatar
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    Very nice! If you don't me asking, what kind of money on the headers themselves?
    89 K1500 Scottsdale 5.7L 5spd 3:42 RamJet cam Dart iron TBI heads 427 PCM swap
    95 C2500 Cheyenne 6.5L turbo diesel 4L80e 4:10 DB2-4911 Manual pump conversion 0411 PCM trans control 2Bar COS
    05 Outback XT 2.5L turbo gas auto

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    Fuel Injected! Roadknee's Avatar
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    $600 shipped.

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    Fuel Injected! Roadknee's Avatar
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    Just got back from a 25 minute loop I like to take when I'm tuning, which includes a flat section of highway where I can run a 0-60 mph pull. I was curious whether the headers would require any changes to the VE tables. Nope. The BLM average were in the 122-128 range; where they've been for the last year. The WOT 0-60 mph run yielded the same 10.0 second time it always has. So my bone stock LO5 shifting at 4,400 rpm sees no benefit at all running a good set of headers and a 2-1/2" Y-pipe as compared to the stock iron manifolds and 2" Y-pipe. Can't say I'm disappointed, or even really surprised. It does sound better. And I'm certain this exhaust system will be much better suited to support the 300 hp engine, once I get around to finishing and installing it.

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    Fuel Injected! JeepsAndGuns's Avatar
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    I too contemplated on a set of headers for my cherokee for a long time. I did end up going ahead and buying some. Mine are full length and I did feel a noticeable difference in power and sound, both for the good. Sorry to hear yours did not make a difference.
    79 Jeep Cherokee, AMC 401, T-18 manual trans, hydroboost, 16197427 MPFI system---the toy

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    99 Jeep WJ Grand Cherokee limited, 4.0L, auto, 2wd, leather and power everything, 99% stock---the long distance highway ride.

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    Quote Originally Posted by Roadknee View Post
    Just got back from a 25 minute loop I like to take when I'm tuning, which includes a flat section of highway where I can run a 0-60 mph pull. I was curious whether the headers would require any changes to the VE tables. Nope. The BLM average were in the 122-128 range; where they've been for the last year. The WOT 0-60 mph run yielded the same 10.0 second time it always has. So my bone stock LO5 shifting at 4,400 rpm sees no benefit at all running a good set of headers and a 2-1/2" Y-pipe as compared to the stock iron manifolds and 2" Y-pipe. Can't say I'm disappointed, or even really surprised. It does sound better. And I'm certain this exhaust system will be much better suited to support the 300 hp engine, once I get around to finishing and installing it.
    Primaries are too small on your headers to see any real HP gains. There is a reason the aftermarket all use 1 5/8" or 1 3/4" primaries. I had a set of Flowtech 115000 1 1/2 primary, 3" collector headers into dual 2.5" exhaust with a X pipe on my 305 and later 350 in my 83 G20 with TBI swap. Going from manifolds to headers and a good exhaust was VERY noticeable even with the small factory marine cam (200/212 @ .050", .400/.410 on 110 lsa) I had in the 305 at the time. I was putting down about 180 RWHP and 270 RWTQ from the 305. I swapped a stock TBI 350 gm crate engine into the 305s place after overheating it an popping a head gasket. Made 178 RWHP and 262 RWTQ. I did a few extra bolt-ons (TBI spacer with open center, power bowl, 454 TBI, 1.6:1 full roller rockers, and an underdrive pulley) )and got it up to 210 RWHP/310RWTQ. When I got serious with the 350, I swapped to Doug Thorley Tri-ys with 1 5/8" primaries, 2" intermediate pipes and 2.5" collectors using the same 2.5" dual exhaust. Even before the cam swap the header change alone was once again very noticeable. With a production LT4 cam, 1.6:1 rockers and my setup I was cranking out 255 RWHP and 320 RWTQ.

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    Fuel Injected! Roadknee's Avatar
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    Quote Originally Posted by Fast355 View Post
    Primaries are too small on your headers to see any real HP gains.
    This can not be any further from the truth based on the experience of professionals that make their living designing and building custom headers and exhaust systems for winning teams

    Quote Originally Posted by Fast355 View Post
    There is a reason the aftermarket all use 1 5/8" or 1 3/4" primaries.
    There is a reason and it's because companies are in business to sell product, and the belief of majority consumers that bigger must be better.

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    Quote Originally Posted by Roadknee View Post
    This can not be any further from the truth based on the experience of professionals that make their living designing and building custom headers and exhaust systems for winning teams

    There is a reason and it's because companies are in business to sell product, and the belief of majority consumers that bigger must be better.
    Actually what I wrote is pretty accurate. Plenty of dyno data out there that supports what I posted as well as personal real world experience. The LT1 cammed 1999 Suburban picked up very noticeably with Hooker 1 5/8 primary long tubes with 2.5" collectors into a Hooker 2.25" dual exhaust setup running thunderbolt 5" spun metallic core cats and hooker aerochamber mufflers.

    My Titan gained almost 30 RWHP on a Mustang dyno stepping up from the factory manifold cats to catless 1 3/4" 14 gauge T304L mid length headers with 2.5" merge collectors into the 2.25" dual exhaust. It was a monster after headers for a 5,800 lbs 4x4.

    The 305 Vortec in the Corvette had a set of stock L82 Ramshorns on it and I put 1 3/4" primary, 2.5" collector headers onto the same dual 2.5" exhaust it had with the ramshorn. Ran 2-3 tenths quicker in the 1/8 with zero other changes.
    Last edited by Fast355; 06-18-2015 at 03:30 AM.

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    I was running 0-70 in 8 seconds in nearly 100*F weather in a 5800# truck with a 5.6L engine and 1 3/4" primary headers. It got out of its own way pretty quickly.

    http://www.youtube.com/watch?v=lELdtvmah2A






    I also towed with it, plenty of low-midrange grunt over stock.


    The Express has Thorley Tri-ys and gained noticeably as well even shifting at only 4,900-5,000 rpm in Tow/Haul mode.




    Doug Thorley even used dual 3" pipes to mate the headers to the factory Express van exhausts. I reduced from 3" to 2.75" to 2.5" at the cats and used a dual in/single out muffler.



    The van has a huge gearing disadvantage compared to the 5spd in the Titan yet it still pulled down a respectable ~8.xs 0-60 and 11 sec 0-70. For a 6,200 lbs beast with only a 3.73 gear and a 4L80E it is not short on torque by any means. The 4L80Es tall 2.48 1st and 1.48 2nd gear ratios are like having a 3.00 rear gear with a 4L60E in first and a 3.23 in 2nd and the 60 lbs stock 13" torque converter also doesn't help the off the line jump very well either, despite having a dual stator and 2,200 rpm stall speed. When you go WOT from idle it kinda lags, hesitates for a second, then takes off like a proded bull!

    http://www.youtube.com/watch?v=-6DZhPN7VHQ

    Finally the 99 Burb....0-80 mph in 13 seconds on an uphill onramp in 90*F weather.

    http://www.youtube.com/watch?v=LYdyu501Z4Y

    Like I said I think I have a little first hand experience at making these engines run pretty strongly.

    I also had both 1 1/2" long tubes and 1 5/8" tri-ys on the same engine in my G20, the larger tri-ys blew the smaller headers away from off-idle through redline.



    When I put the healthy TPI enging into the G20 I was glad I had the extra headroom to make more power.

    Last edited by Fast355; 06-18-2015 at 02:27 PM.

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    Im no expert but I've done a ridiculous amount of research in choosing headers for my build. The general consensus on primary size is where you want your power, smaller = low and mid range while larger = more top end. Port alignment and collector size/design are every bit as important as primary size. Just because you saw gains with larger primaries doesn't mean it is because they were larger, its the complete package that makes a difference.

    Superchevy has an article on a header test using a smeding 383 and 4 different size headers. The 1 1/2" primary, while intended to just establish a base line for the test, supported well over 400 hp and ended providing the best overall power curve below 5000 rpm. The larger sizes didn't pull ahead until 4500+ and at the sacrifice of low end. Headers by Ed states that there is no point in having a primary size larger than your exhaust valve so if you have a typical svc with 1.5" valves, no need. Unless you're building a high rpm motor, bigger is not better.

    If your talking vortec heads, the biggest problem is port alignment. Unlike standard sbc heads, vortec's have a raised port (approx 60% of the port is above the bolt centerline) so smaller primary headers tend to cover the top of the port. Bigger primaries while uncovering the whole port present sealing problems at the bottom of the flange.

    I myself went with a set of flowtec 11508 flt headers (less than $150). Basically the same headers in superchevy's test, 1 1/2 primary and 2 1/2 collector. Replaced the wimpy 1/4" flanges with a set of 3/8" cnc cut flanges that I bought on ebay from Hells Gate Hotrods. He sells a set of sbc for $45 and made me a custom set for the vortec port alighnment for less than $100. I went a step further and bought a set of Meg's weld on merge collectors from cone engineering for $125. After finish assembly I sent them to a place called pro kote Indy in Indianapolis and had them professionally cleaned and ceramic coated for $220. Just got them back and they look awesome. For less than $600 I got ceramic coated, perfect fit headers with perfect port alignment and plenty of sealing surface.

    Assembling motor now. Let you know how the do when I get it running.
    95 GMC K2500, 4l80e, 4.10 gears, 355 L05 4-bolt block, ARP rod bolts, Speed-Pro H423DCP-30 pistons, moly rings, 217 heads, vortec cam, TBI mods, cop car injectors, headers, 2 1/2" Y-pipe and 3" single exhaust with high flow muffler and cat.

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    Im no expert but I've done a ridiculous amount of research in choosing headers for my build. The general consensus on primary size is where you want your power, smaller = low and mid range while larger = more top end. Port alignment and collector size/design are every bit as important as primary size. Just because you saw gains with larger primaries doesn't mean it is because they were larger, its the complete package that makes a difference.

    Superchevy has an article on a header test using a smeding 383 and 4 different size headers. The 1 1/2" primary, while intended to just establish a base line for the test, supported well over 400 hp and ended providing the best overall power curve below 5000 rpm. The larger sizes didn't pull ahead until 4500+ and at the sacrifice of low end. Headers by Ed states that there is no point in having a primary size larger than your exhaust valve so if you have a typical svc with 1.5" valves, no need. Unless you're building a high rpm motor, bigger is not better.

    If your talking vortec heads, the biggest problem is port alignment. Unlike standard sbc heads, vortec's have a raised port (approx 60% of the port is above the bolt centerline) so smaller primary headers tend to cover the top of the port. Bigger primaries while uncovering the whole port present sealing problems at the bottom of the flange.

    I myself went with a set of flowtec 11508 flt headers (less than $150). Basically the same headers in superchevy's test, 1 1/2 primary and 2 1/2 collector. Replaced the wimpy 1/4" flanges with a set of 3/8" cnc cut flanges that I bought on ebay from Hells Gate Hotrods. He sells a set of sbc for $45 and made me a custom set for the vortec port alighnment for less than $100. I went a step further and bought a set of Meg's weld on merge collectors from cone engineering for $125. After finish assembly I sent them to a place called pro kote Indy in Indianapolis and had them professionally cleaned and ceramic coated for $220. Just got them back and they look awesome. For less than $600 I got ceramic coated, perfect fit headers with perfect port alignment and plenty of sealing surface.

    Assembling motor now. Let you know how the do when I get it running.
    95 GMC K2500, 4l80e, 4.10 gears, 355 L05 4-bolt block, ARP rod bolts, Speed-Pro H423DCP-30 pistons, moly rings, 217 heads, vortec cam, TBI mods, cop car injectors, headers, 2 1/2" Y-pipe and 3" single exhaust with high flow muffler and cat.

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    Quote Originally Posted by old truck guy View Post
    Assembling motor now. Let you know how the do when I get it running.
    The cam in your signature is one of the ones I considered using. It actually came down to the that one and the one I am using now which has much less lift. I'd like to hear how it works for you.

    BLG
    Last edited by BLG355; 06-26-2015 at 03:13 PM.
    My Build: 95 K1500, 355ci w/ OEM roller setup - zero decked, Eagle steel crank, Scat bushed H-beam rods, Speed Pro 2V flat top pistons - Rotating assembly balanced. Dart 165cc Iron Eagle S/S heads - 72cc chambers - 1.94 / 1.50 valves. Isky roller cam - 204/209 dur @ .050 - .480/.496 lift with Comp Magnum 1.6 rockers, Edelbrock 3704 intake - Bored to 52mm - 454 throttle body, Delco EP381 fuel pump @ 18 psi running through 80# 454 injectors. Hedman Headers into 3" Dynomax exhaust.

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    Quote Originally Posted by BLG355 View Post
    The cam in your signature is one of the ones I considered using. It actually came down to the that one and the one I am using now witch has much less lift. I'd like to hear how it works for you.

    BLG
    Yeah I was concerned about lift too. Spring upgrade in my vortec's is good to about .550 which is right where the advertised lift for my cam is but it's spec'd with 1.6 rockers. I went with 1.52 which brings my total lift down to about .522. Your, s sounds like a nice build. A bit more than mine. Is that isky enough cam?
    95 GMC K2500, 4l80e, 4.10 gears, 355 L05 4-bolt block, ARP rod bolts, Speed-Pro H423DCP-30 pistons, moly rings, 217 heads, vortec cam, TBI mods, cop car injectors, headers, 2 1/2" Y-pipe and 3" single exhaust with high flow muffler and cat.

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    Fuel Injected! BLG355's Avatar
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    I thought about going with a larger cam, but I do planning on doing some towing and I wanted a big increase over stock without any drivability issues. To keep things simple to pass the PA emissions test, I decided to go with the Edelbrock TBI intake so the EGR was physically bolted in the proper place. So that lead me to look at the Dart S/S heads, which stop increasing flow rate at .500" lift. And the dart heads have a very nice combustion chamber, plus it is 72cc. I wanted to keep a good quench distance of .039 and with flat tops with only 2 valve reliefs, I am right at 8.0 dynamic compression with this cam. So, for this motor, this cam has incredible torque, plus just enough to pull 5500rpm shift points. I upgraded to the 454 throttle body because I was down to 88kpa at 5200rpm, now the motor is over 95kpa at 5500+ rpm(not that I need it there). If I was going with different heads I probably would have went for the comp cam, but I do love Isky grinds. I use them in race motors with excellent results.

    BLG
    My Build: 95 K1500, 355ci w/ OEM roller setup - zero decked, Eagle steel crank, Scat bushed H-beam rods, Speed Pro 2V flat top pistons - Rotating assembly balanced. Dart 165cc Iron Eagle S/S heads - 72cc chambers - 1.94 / 1.50 valves. Isky roller cam - 204/209 dur @ .050 - .480/.496 lift with Comp Magnum 1.6 rockers, Edelbrock 3704 intake - Bored to 52mm - 454 throttle body, Delco EP381 fuel pump @ 18 psi running through 80# 454 injectors. Hedman Headers into 3" Dynomax exhaust.

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    Fuel Injected! Roadknee's Avatar
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    Quote Originally Posted by Fast355 View Post
    Like I said I think I have a little first hand experience at making these engines run pretty strongly.
    I don't think you'll find anyone who will disagree with that. I've personally been very impressed with your results for about a decade now. I simply don't agree with your opinion that 1-1/2" headers are holding back my stock LO5. FWIW, I don't think it would gain or lose anything measurable with a decent set of 1-5/8" headers either.

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