40 horsepower headers
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From: Hudson WI
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40 horsepower headers
I keep reading about 40 horsepower headers on stock engines.
Does that sound high, or is it just me being skeptic? I know a guy that did back to back tests on an engine dyno in Detroit that told me that he saw very little gain on a stock engine with headers. He built the engine in one of the past Optima Ultimate Street Car events after SEMA and his car won the one the regional events, so he knows what he is doing.
And yes, I have headers on my car and it makes good horsepower numbers, but it is also a stroked LS3.
Opinions welcome, but more important, dyno sheets with headers only and no tune.
Does that sound high, or is it just me being skeptic? I know a guy that did back to back tests on an engine dyno in Detroit that told me that he saw very little gain on a stock engine with headers. He built the engine in one of the past Optima Ultimate Street Car events after SEMA and his car won the one the regional events, so he knows what he is doing.
And yes, I have headers on my car and it makes good horsepower numbers, but it is also a stroked LS3.
Opinions welcome, but more important, dyno sheets with headers only and no tune.
Last edited by timd38; Jan 28, 2014 at 09:22 AM.
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I was 375 rwhp - 381 rwtq stock LS3 manual.
After headers catted and a tune I showed 422 both rwhp/tq.
Gain of 47 hp and 41 tq.
Car had 800 miles when original dynoed and with a tune at this point I was 400 rwhp/tq.
So the headers add 22 hp/tq as alone mod.
American Racing 1 3/4 in. catted.
After headers catted and a tune I showed 422 both rwhp/tq.
Gain of 47 hp and 41 tq.
Car had 800 miles when original dynoed and with a tune at this point I was 400 rwhp/tq.
So the headers add 22 hp/tq as alone mod.
American Racing 1 3/4 in. catted.
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Joined: Aug 2005
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From: Hudson WI
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I was 375 rwhp - 381 rwtq stock LS3 manual.
After headers catted and a tune I showed 422 both rwhp/tq.
Gain of 47 hp and 41 tq.
Car had 800 miles when original dynoed and with a tune at this point I was 400 rwhp/tq.
So the headers add 22 hp/tq as alone mod.
American Racing 1 3/4 in. catted.
After headers catted and a tune I showed 422 both rwhp/tq.
Gain of 47 hp and 41 tq.
Car had 800 miles when original dynoed and with a tune at this point I was 400 rwhp/tq.
So the headers add 22 hp/tq as alone mod.
American Racing 1 3/4 in. catted.
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From: Northern, VA
St. Jude Donor '15
"In honor of jpee"
as to your question, as said above from what I've seen headers and tune can go maybe close to/in the vicinity of 40 rwhp. but that may be on different days (baseline to header/tune installation), and in fact, there may be no baseline done at all---just an estimate of what the car's putting down. in which case, if someone "assumes" the car's a 375 rwhp (LS3) stock engine car, coming on w. a sheet that says 405 rwhp seems (almost) reasonable, right? but what if it really was a 385 or 390 stock engine at the time of the headers and tune? hmmm.....
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From: St. Louis, MO
St. Jude Donor '08
50 rwhp from a tune and CAI and headers is about right on an ls2, ls3 will get a little less as the air cleaner is better on an ls3.
Here are the dyno results from all my mods from CAI/Headers/Tune to heads and cam.
http://forums.corvetteforum.com/c6-t...ast-heads.html
Here are the dyno results from all my mods from CAI/Headers/Tune to heads and cam.
http://forums.corvetteforum.com/c6-t...ast-heads.html
Decided yesterday to overlay all my mods since I've self tuned and dyno'ed each time I did major mods.
I found it interesting and thought I'd share.
See below. Each line represents progressive mods:
1. stock;
2. headers & tune (3.90 gears at same time);
3. G5x3 cam & .040 gaskets (11.4 compression);
4. FAST, and
5. used AFR 205 heads.
What strikes me is how dramatic the gains from headers and a tune were. Combined with the gears, it felt like a different car, and I got a full second + 10 mph in the 1/4 from those mods, from 12.9@108 to 11.8@118. The car was dead nuts reliable at this level.
The second take away is how all the remaining mods really only mattered from 4500 on. Thus I very seldom notice them on the street, only on the track. Not counting the cool sound of the cam.
Mods 3-5 did take off another second and added 10 mph - to 10.8@128. But it cost a lot more and I broke a diff and two transmissions on my way.
This graph shows what I've been saying for while; headers, tune and gears give you by far the best bang for the buck from idle to redline, the remaining mods only matter from 4500 on. Most street driving is below 3000 rpm...you do feel gears and headers even at that level.
Hope someone finds this useful as they decide upon mods.
I need to add...without question...the best drag strip mod for return on $$ is...
SEAT TIME.
And personally, I find that mod the most rewarding.
Another item Tommy kindly reminded me of, is weight reduction.
If you are drag racing, you can expect .1 to .15 from putting skinny tires up front (saving 50 lbs+ of rotating weight) and taking out your passenger seat (53 lbs).
I found it interesting and thought I'd share.
See below. Each line represents progressive mods:
1. stock;
2. headers & tune (3.90 gears at same time);
3. G5x3 cam & .040 gaskets (11.4 compression);
4. FAST, and
5. used AFR 205 heads.
What strikes me is how dramatic the gains from headers and a tune were. Combined with the gears, it felt like a different car, and I got a full second + 10 mph in the 1/4 from those mods, from 12.9@108 to 11.8@118. The car was dead nuts reliable at this level.
The second take away is how all the remaining mods really only mattered from 4500 on. Thus I very seldom notice them on the street, only on the track. Not counting the cool sound of the cam.
Mods 3-5 did take off another second and added 10 mph - to 10.8@128. But it cost a lot more and I broke a diff and two transmissions on my way.
This graph shows what I've been saying for while; headers, tune and gears give you by far the best bang for the buck from idle to redline, the remaining mods only matter from 4500 on. Most street driving is below 3000 rpm...you do feel gears and headers even at that level.
Hope someone finds this useful as they decide upon mods.
I need to add...without question...the best drag strip mod for return on $$ is...
SEAT TIME.
And personally, I find that mod the most rewarding.
Another item Tommy kindly reminded me of, is weight reduction.
If you are drag racing, you can expect .1 to .15 from putting skinny tires up front (saving 50 lbs+ of rotating weight) and taking out your passenger seat (53 lbs).
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From: Hudson WI
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I guess the moral of the story is that when people install headers, they get a tune and then it appears that they got 40hp from the headers, I guess you could say that is true, because you need a tune when you get the headers.
That bring said, a header install really costs about, say, $400 more because of the cost of the tune.
That bring said, a header install really costs about, say, $400 more because of the cost of the tune.
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From: St. Louis, MO
St. Jude Donor '08
I guess the moral of the story is that when people install headers, they get a tune and then it appears that they got 40hp from the headers, I guess you could say that is true, because you need a tune when you get the headers.
That bring said, a header install really costs about, say, $400 more because of the cost of the tune.
That bring said, a header install really costs about, say, $400 more because of the cost of the tune.
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Joined: Nov 2013
Posts: 431
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From: Oconomowoc Wisconsin
Tune magic...
I guess the moral of the story is that when people install headers, they get a tune and then it appears that they got 40hp from the headers, I guess you could say that is true, because you need a tune when you get the headers.
That bring said, a header install really costs about, say, $400 more because of the cost of the tune.
That bring said, a header install really costs about, say, $400 more because of the cost of the tune.
What I thought was amazing is they felt there was 30% more performance in a custom tune vs. what the factory gives you. They thought the factory tune gives you about 70% of what the engine could do. Now does that mean go dial it in and expect to get the same longevity that the factory tune give you...probably not but GM has this thing called a warranty and fleet mileage numbers and emissions, etc. they give you what they give you for many reasons.
But do some mods and wrap them with a good tune and get the fuel/air ratios where you want them, timing and on and on and you should be able to keep your longevity and enjoy a bunch of extra fun...
Last edited by vforrest; Jan 29, 2014 at 11:12 AM.
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C6 of Year Finalist (performance mods) 2019
Dyno numbers are pretty meaningless unless you are using them as a comparison during the same dyno session. When the circumstances change, so do the results.
Here's some of my numbers and I'm sure they won't fit with expectations of the results. Since dynos make adjustments for DA, the PB track times I list have also been DA adjusted.
Bone stock 12.40
propped shroud 12.17
added tune 12.16 -- Dyno 1st pull 306hp - final pull 320hp
added CAI plus retune 11.92
added Z06 mufflers 11.90
added DR 11.81
tweaked tune 11.72
added Z06 manifold/h-pipe retune -- Dyno 1st 372hp - final 386hp 11.64
3200 converter 11.34
tweaked tune 11.19
3600 converter 10.92
swapped Z06 for headers/added ported manifold -- Dyno 1st 410hp - last 411hp 10.83
So according to my Dyno HP, there should be lots of LS3 bolton cars running 10's who have those 420-450 HP Dyno sheets with the 40 HP headers and 46 HP CAI.
Now that I've switched to a 4000 stall I managed a 1.56 60' in 4600' DA to match my PB 60' time that was done in 300' DA. My Dyno HP hasn't changed, but I'm expecting 10.6x's in good air.
Here's some of my numbers and I'm sure they won't fit with expectations of the results. Since dynos make adjustments for DA, the PB track times I list have also been DA adjusted.
Bone stock 12.40
propped shroud 12.17
added tune 12.16 -- Dyno 1st pull 306hp - final pull 320hp
added CAI plus retune 11.92
added Z06 mufflers 11.90
added DR 11.81
tweaked tune 11.72
added Z06 manifold/h-pipe retune -- Dyno 1st 372hp - final 386hp 11.64
3200 converter 11.34
tweaked tune 11.19
3600 converter 10.92
swapped Z06 for headers/added ported manifold -- Dyno 1st 410hp - last 411hp 10.83
So according to my Dyno HP, there should be lots of LS3 bolton cars running 10's who have those 420-450 HP Dyno sheets with the 40 HP headers and 46 HP CAI.
Now that I've switched to a 4000 stall I managed a 1.56 60' in 4600' DA to match my PB 60' time that was done in 300' DA. My Dyno HP hasn't changed, but I'm expecting 10.6x's in good air.
Tech Contributor
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From: St. Louis, MO
St. Jude Donor '08
Tom, I actually have noticed that Dynojet 248 Inertia dynos are VERY comparable from location to location and day to day...IF and only IF their weather stations are accurate.
There was a thread a while back of LS2 guys posting up their dyno results for mods....and it was SCARY consistent from locale to locale and car to car.
There was a thread a while back of LS2 guys posting up their dyno results for mods....and it was SCARY consistent from locale to locale and car to car.
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From: Indianapolis IN
Joe, when you say you broke stuff after all the mods,,,,,,,,,,,, do you think a street car without drag launches would have the same problem with breakage? Only aggressive acceleration / spirited riving etc
I appreciate your posting your results, the over 4500 RPM results make sense, I had the same issue on my 1985 406 ci build, that's why I went fro big TQ after being disappointed while driving around the city
I appreciate your posting your results, the over 4500 RPM results make sense, I had the same issue on my 1985 406 ci build, that's why I went fro big TQ after being disappointed while driving around the city
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From: St. Louis, MO
St. Jude Donor '08
Joe, when you say you broke stuff after all the mods,,,,,,,,,,,, do you think a street car without drag launches would have the same problem with breakage? Only aggressive acceleration / spirited riving etc
I appreciate your posting your results, the over 4500 RPM results make sense, I had the same issue on my 1985 406 ci build, that's why I went fro big TQ after being disappointed while driving around the city
I appreciate your posting your results, the over 4500 RPM results make sense, I had the same issue on my 1985 406 ci build, that's why I went fro big TQ after being disappointed while driving around the city
What breaks parts is wheel hop, and street tires wheel hop more than drag radials by a mile. Avoid wheel hop at all costs. Let out.
What also breaks parts is shifting too fast and missing gears. 3rd gear blocker ring is weak in a T56. Go easy on it.
A c5 or c6 is a very reliable car on the street or track with boltons, which is a high 11 second car.
Once you go into the 10's which is around 500 rwhp, give or take 30 or so, you are exceeding the limits of the drive train and things are going to break. It's just a matter of time. I would tell you that a high 11 second car is going to last a long time with 400 rwhp or so.
If you want things to last, a z06 rear end is much stronger, as is the 08+ 6060 transmission.
For your use as you propose, so long as you avoid any wheel hop, your car will last a very long time. These are wonderfully engineered and built cars.
The best bang for buck for cruising the city is 4.10 gears by the way. Over anything else it makes the car feel like it lost 500 lbs.
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From: St. Louis, MO
St. Jude Donor '08
I always recommend both. And for an ls2, a cold air intake makes a huge difference as well as it gives you back up to 12 degrees of timing due to the stock IAT timing reduction table. LS3's have a great stock air filter so all you have to do is prop open the shroud (some report surging from doing this however as the MAF is sensitive).
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St. Jude Donor '15
"In honor of jpee"
Dyno numbers are pretty meaningless unless you are using them as a comparison during the same dyno session. When the circumstances change, so do the results.
Here's some of my numbers and I'm sure they won't fit with expectations of the results. Since dynos make adjustments for DA, the PB track times I list have also been DA adjusted.
Bone stock 12.40
propped shroud 12.17
added tune 12.16 -- Dyno 1st pull 306hp - final pull 320hp
added CAI plus retune 11.92
added Z06 mufflers 11.90
added DR 11.81
tweaked tune 11.72
added Z06 manifold/h-pipe retune -- Dyno 1st 372hp - final 386hp 11.64
3200 converter 11.34
tweaked tune 11.19
3600 converter 10.92
swapped Z06 for headers/added ported manifold -- Dyno 1st 410hp - last 411hp 10.83
So according to my Dyno HP, there should be lots of LS3 bolton cars running 10's who have those 420-450 HP Dyno sheets with the 40 HP headers and 46 HP CAI.
Now that I've switched to a 4000 stall I managed a 1.56 60' in 4600' DA to match my PB 60' time that was done in 300' DA. My Dyno HP hasn't changed, but I'm expecting 10.6x's in good air.
Here's some of my numbers and I'm sure they won't fit with expectations of the results. Since dynos make adjustments for DA, the PB track times I list have also been DA adjusted.
Bone stock 12.40
propped shroud 12.17
added tune 12.16 -- Dyno 1st pull 306hp - final pull 320hp
added CAI plus retune 11.92
added Z06 mufflers 11.90
added DR 11.81
tweaked tune 11.72
added Z06 manifold/h-pipe retune -- Dyno 1st 372hp - final 386hp 11.64
3200 converter 11.34
tweaked tune 11.19
3600 converter 10.92
swapped Z06 for headers/added ported manifold -- Dyno 1st 410hp - last 411hp 10.83
So according to my Dyno HP, there should be lots of LS3 bolton cars running 10's who have those 420-450 HP Dyno sheets with the 40 HP headers and 46 HP CAI.
Now that I've switched to a 4000 stall I managed a 1.56 60' in 4600' DA to match my PB 60' time that was done in 300' DA. My Dyno HP hasn't changed, but I'm expecting 10.6x's in good air.
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I will go forward with the plan of ported intake, headers, cam, tune, maybe Lingenfelter ported LS2 heads if I get the urge.
Already have a NXT Catback and already have a Callaway Honker.
Thanks for everyone's input, I've been slow on mods, but I have added a new Double D Mods Kenwwood stereo sub, amp and speakers, and new tires and ZO6 wheels,
Already have a NXT Catback and already have a Callaway Honker.
Thanks for everyone's input, I've been slow on mods, but I have added a new Double D Mods Kenwwood stereo sub, amp and speakers, and new tires and ZO6 wheels,
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From: Peoria/Phoenix AZ
C6 of Year Finalist (performance mods) 2019
those are some dramatic drops in ET and increases in HP even taking what you said re different days, track/atmosphere conditions. The most interesting to me is from bone stock to just before a trans converter, not to mention the initial 306 rwhp going up to 386 w. Z manifolds/full exh., CAI and tune. Not to mention a drop w. drag radials added of 3/4 sec.
BTW, the DR's only produced a .09 improvement, which was due to the ability to launch harder.