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Let's talk about longtube headers...

75K views 180 replies 37 participants last post by  TexasRed 
#1 ·
Recently a good customer of ours said he wanted to do some exhaust upgrades. Longtube headers and catback system. He was afraid of losing power because he heard that longtube headers on the HC platform cause this to happen.

I just wanted to start this thread to see what your thoughts are on this subject. Not to tear anybody down, just to get you guys the right information. I'm sure there are some out there that will agree with what we have to say and there will be plenty out there that will fight us every step of the way. Regardless, this will be a nice way to breakdown some of the misleading information about adding longtube headers to your HC platforms.


....ready, set, go!
 
#6 ·
No worries Sammy. I wasn't trying to poke fun at ya or anything. I just hear guys talk about this subject and move on to the next mod because they heard someone say something about headers losing power. What's surprising to me is that no one actually takes the time to break down what's happening when you add longtube headers to a HC.
 
#7 ·
Longer primaries increase peak power below peak torque, loosing power above peak torque. Length changes move the amount of torque above or below peak torque rpm. Too short peaks exhaust gas velocity too early in rpm curve limits top end hp. Too large you get very peaky output.

Diameter affects flow / velocity, smaller better mid range torque, falls off higher rpm. Larger adds high rpm power at expense of low speed torque.

Your'e moving peak torque, hp and their curve envelope widths in relation to rpm and each other when changing headers.

In short you should have a goal and I bet you do Skip. (Still lots of heavy lifting manno you guys must have big Gorilla guns.) So what are you cooking up headers wise?
 
#9 ·
Longer primaries increase peak power below peak torque, loosing power above peak torque. Length changes move the amount of torque above or below peak torque rpm. Too short peaks exhaust gas velocity too early in rpm curve limits top end hp. Too large you get very peaky output.

Diameter affects flow / velocity, smaller better mid range torque, falls off higher rpm. Larger adds high rpm power at expense of low speed torque.

Your'e moving peak torque, hp and their curve envelope widths in relation to rpm and each other when changing headers.

In short you should have a goal and I bet you do Skip. (Still lots of heavy lifting manno you guys must have big Gorilla guns.) So what are you cooking up headers wise?
Great break down man! This helps the technical guys. What about the avg Joe? What do you think goes through their head when they hear "Longtube headers are useless on the HellCat" ?

What I heard about the longtube headers on our platform was there was no gains at the track on a car that had them installed . Not sure which manufacturer headers were installed. If a vendor makes some with proven results that contradict this Im all over it.
We're not trying to make a new set of headers for you guys. Plenty of top tier major players in the header game already have this covered. We're just wanting to see what data and information you guys have on them. This guy that added the longtubes, did he compensate for the loss of boost that was experienced after opening up the airways? Or did they simply install the headers and go out and make run thinking they would pick up a ton of power mid/top end?
 
#10 ·
I know Topcat tried them and they did not help his car. My understanding was always that they lower boost but still make similar horsepower.
 
#11 ·
I'm sure he lost boost pressure from the addition of the headers. I'm sure his cylinder pressure also went down with the addition of headers too. Similar hp at the same boost levels or did they compensate for the loss of boost by way of a smaller pulley to make up the difference? This is a pretty important thing to factor in when comparing boosted power vs boosted power.

A 15psi HC would probably run faster than a 14psi HC with headers right? I can bet you that 14psi HC with headers is probably a happier running motor overall however. Once you compensate for the loss of boost I'm sure there will be substantial gains to be seen across the power band at the same boost level.
 
#12 ·
Headers on a Hellcat is a complete waste of money, period, Topcat used them, told the forum and me that they were a waste of money. I was a jackass and bought them anyway, American Racing Headers complete system, I cannot see the difference. NYCSRT (Eric) went 9.71 in 93 degrees in Milan with terrible air with stock exhaust, he is going to go 9.5 or better with good air at Atco. When you can go 9.5 with the stock exhaust, I say headers are a waste of money.
 
#14 ·
Skip,

In theory I should be making less boost, however without your 3 bar MAP sensors I do not know. My point is if you can go 9.5's with the stock shorties and this is possible (Linda went 9.71 with boost only), then why spend the money for the full length headers? I would not be surprised if NYCSRT went into the 9.4's at Atco. Maybe they are good for 20 HP but to pay $ 3,000.00 for 20 HP is just not a good bang for the buck. Plus they are a ***** to install. Maybe if the goal is to max out a 93 tune Cat, then full length headers and camshaft makes some sense. I am just trying to save the members here some money.

Skip, thank you for sponsoring the MSHS event in Virginia, great time. Demon Performance produces some really quick jeeps and for the first time this whole year I actually got around a jeep in the 9.5 class (I do not know what shop the jeep was from). Always good talking with you and Laser Doc's build is really exciting. I know he will keep us posted. Will you attend Atco?
 
#17 ·
Skip,

In theory I should be making less boost, however without your 3 bar MAP sensors I do not know. My point is if you can go 9.5's with the stock shorties and this is possible (Linda went 9.71 with boost only), then why spend the money for the full length headers? I would not be surprised if NYCSRT went into the 9.4's at Atco. Maybe they are good for 20 HP but to pay $ 3,000.00 for 20 HP is just not a good bang for the buck. Plus they are a ***** to install. Maybe if the goal is to max out a 93 tune Cat, then full length headers and camshaft makes some sense. I am just trying to save the members here some money.

Skip, thank you for sponsoring the MSHS event in Virginia, great time. Demon Performance produces some really quick jeeps and for the first time this whole year I actually got around a jeep in the 9.5 class (I do not know what shop the jeep was from). Always good talking with you and Laser Doc's build is really exciting. I know he will keep us posted. Will you attend Atco?
I'm sure you're making less boost with the addition of the longtubes. What pulley combination are you running? If you're making less than 18psi then send me over your WOT logs pre headers and post headers and I can tell you exactly what type of pressure loss you're experiencing from the addition of longtube headers. You don't need a 3 bar map to loss of pressure, we can see that throughout a log even if you're making slightly more than 18psi. I understand that you can run very fast without the addition of headers and they are not cheap to purchase/install. That's not what I'm trying to prove here at all however. I'm trying to dissect the information you guys have and maybe do our own testing to prove other wise. I believe in engine efficiency through and through, a HC motor running higher amounts of boost with longtube headers will experience less cylinder pressure, no doubt it. Which results in a healthier running setup under higher loads. It will in turn lose boost pressure due to the airways being opened up, which in turn equates to loss of power(in a nut shell). We have countless 1000+ whp cars out there equipped with the right parts to make then run hard and still be very reliable, most of which have headers. Our big race turbo jeeps also have custom mid length headers that help with spool efficiency on these big turbos we run. The hunt for power has no set price tag either. If you want to be the fastest, you have to be willing to pull out all stops and do what's necessary to make that happen. I know TC and Linda have thrown a lot of things at their cars and I know they've done plenty of before and after testing, over and over. One persons findings don't always hold true however, there are a ton of variables to consider. We always respect and appreciate when people are testing things for the greater good.

We love being a sponsor at these events. It's always a pleasure coming out and helping our customers and other racers too. Having track side support is a very nice thing for the newer generation of racers too. We will most certainly be at ATCO, we are not the main event sponsor like we were with this past VMP but we will always sponsor the Super Pro class regardless. We hope to have a couple 8second runners this time out too. The cooler weather will def help our cause ;)


The other problem with compensating for boost loss is that with a 2.75 upper and 10% lower Im not comfortable spinning the supercharger any faster. At least not until someone gets hard numbers from ihi on the critcal speed for our superchargers
What boost levels are you seeing? Are you past the TMAP readings? I'll make some calls. We have some connections that may get us the info you seek. I understand your concern too, ruining a 10k blower assembly is not something anyone wants to experience.

Hey Skip,
You can't be sure of anything you have not seen yourself. I see a post like this and I get why you may defensive and I am also too.
"The Truth is Told At the Track."
The Best way for you "to be sure" of anything is give us your track proven information.
This is what "Top Cat" provided to our forum memebers. The Hell Cat R+ D is still being tested in many Performance shops. ;)
I agree with Cole, Thanks for your sponsorship to the MSHS races and for everything you did at VMP was a very nice for all in attendance.
Linda:)
Linda, I'm a firm believer in the saying "The proof is in the pudding" Over the years we've said "I told you so" to many a naysayer and shops alike. We hate being right in this type of manner, but we don't talk about something until we have hard data. I know TC did a lot of things on the proving grounds, but that doesn't mean that if his results and findings were poor that we should write it off. I bet if he had a keyboard and the internet in heavan he would be on my case right now going back and forth with me.

Track proven information and dyno data is what we always back our testing with. Not false advert and snake oil lol. I love how some places sell you fancy pictures and badging though, makes my chuckle when you see their results!

I tell you what. I'll give this a go with a HC soon. We already have pre header dyno data on it and know exactly what it makes for boost. We'll add a set of longtubes into the mix and compensate for the loss boost by way of an upper. We'll run it on the same dyno under the same conditions with the same boost levels as previously tested. That should give us the necessary proof in the numbers. If we lose power, I'll bite my tongue on this subject and let it go.
 
#16 ·
I'm sure he lost boost pressure from the addition of the headers. I'm sure his cylinder pressure also went down with the addition of headers too. Similar hp at the same boost levels or did they compensate for the loss of boost by way of a smaller pulley to make up the difference? This is a pretty important thing to factor in when comparing boosted power vs boosted power.

A 15psi HC would probably run faster than a 14psi HC with headers right? I can bet you that 14psi HC with headers is probably a happier running motor overall however. Once you compensate for the loss of boost I'm sure there will be substantial gains to be seen across the power band at the same boost level.

Hey Skip,
You can't be sure of anything you have not seen yourself. I see a post like this and I get why you may defensive and I am also too.
"The Truth is Told At the Track."
The Best way for you "to be sure" of anything is give us your track proven information.
This is what "Top Cat" provided to our forum memebers. The Hell Cat R+ D is still being tested in many Performance shops. ;)
I agree with Cole, Thanks for your sponsorship to the MSHS races and for everything you did at VMP was a very nice for all in attendance.
Linda:)
 
#18 ·
What boost levels are you seeing? Are you past the TMAP readings? I'll make some calls. We have some connections that may get us the info you seek. I understand your concern too, ruining a 10k blower assembly is not something anyone wants to experience.

Skip
If you can find the RPM limits of the stock blower that would be great! Please let us know if you find the answer.
 
#27 · (Edited)
If you can find the RPM limits of the stock blower that would be great! Please let us know if you find the answer.
I will do my best for ya.

Skip,
I'm seeing 32.2psi or so on the map sensor with my setup. I think thats about the max the sensor can read. I know of at least 3 cars that have had SC failures. It would be awesome if somebody could find out those specs from ihi, I'm sure they have tested their product to a failure point
Yep, looks to me like it's pegged out for sure. SC failures are really though to dissect. If they were making gobbs of boost and spinning it beyond it max efficiency rpm zone then I'm sure that didn't help the blower either.

Skip,

I am pegging out the MAP sensor, I run the 2.4 pulley with no slip, without 3 bar MAP sensors the data logs are telling you nothing . I am running well north of 18 pounds of boost. What I am telling you is my brother, Team Hellcat NYCSRT is running the same traps as me with stock exhaust, with a cat delete. Linda is running 9.71 with Boost only with stock exhaust.
Why would anyone spend 3K or more to run the same times? Yes, the long tube headers might, in theory make more HP, but it is not equating to track times. I say spend the 3K on a family trip, spending on headers is pissing money away, I know, I did it, even though Top Cat told me otherwise. If you think that you can design a better header than Cooks or American Racing Headers, go for it. All I can say is that some of the fastest hellcats to date, do not run headers.

Skip, NYCSRT has trapped 143.7 with stock exhaust, I have trapped a best of 143.9, both in heat and shitty air. Do you think the difference is worth 3K?
How do you know there's no slip? Without a 3 bar MAP in place your MAP readings will always be flat-lined when going WOT if you're making more than 18psi. Belt slip doesn't always have to be a sound or shredding of a belt, we go through countless belt problems on other applications when guys are trying to make big boost on a 6 rib drive that can't grip the load. I'm not arguing with you on the cost vs gains for headers. They are not cheap, they are not easy to install. Has anyone really tested them apples to apples on the same application, on the same dyno, under the same conditions, running the same boost levels to see where the differences in the power is, if any?

Not more like, they are shorty headers
They are, not arguing with you there either.
 
#23 ·
I never even thought about headers. I have seen 3 Hellcats with headers all with 850+ rwhp and the gains were so minimal its not worth the money. Granted to get the real rwhp gain if the car loses 2 psi add the 2 psi back and compare the two. Most I seen was 27 rwhp to the ground. Cars making this kind of power the gains should be big if there is a exhaust restriction.

Mike
 
#24 · (Edited)
I won't be doing headers.

This discussion is identical to cam selection on 5.9 Cummins. An aftermarket should make more power, but there are many people out there making 1,000+hp on the stock cam.

To me, this is one of those things that you can get away with not doing. Does it help? It has to, just the paper specs says it will, but, sometimes paper doesn't work into the real world.

On another note, I'll be doing a cam, not for the power, maybe I'll get a little power, but I want the chop chop. Nothing says power like a little chop. I'm really vain like that.
 
#31 ·
Skip,

You are on fire this morning, asking some tough questions on a few threads. Attached is photo of my belt setup, I can safely say there is no slip going on the pulley. I cannot address your questions as I did not perform dyno pulls before and after the install. View attachment 80993
Meh, just the usual Monday morning start for me.

I see that you have the added idler, we've also done that here on a few applications as well.

skip potstirring arnt you unless you gonna make em
Nah, not going to make new headers, just going to do a true apples to apples test with a set of Kooks to show you what we find. I've had a few guys in the past month tell us that headers lose power because someone said so. We don't work that way. If they truly lose power, then I'll let you guys know here soon enough. shadowsk has been gracious enough to allow us to perform this test on his vehicle as we've already worked on it. It made a little over 700whp with a lower upgrade added to the mix and our tuning. We'll add in the headers and see how much boost we lose and then we'll add an upper to compensate for the loss. Most likely a 3.10 upper should do the trick to get it back up to the current boost level. Then we'll hit the rollers and over lay the data to compare.
 
#36 ·
Cats or cat delete is another variable.
Didn't Top Cat do cat delete to run race gas?
 
#40 ·
I do not know, without 3 bar MAP sensors, very tough to tell. Josh may know. It may be similar to boost reduction you get if you run the mid pipe cat delete pipe in stock exhaust system. I have never read a post where the boost reduction was documented (assuming there is a reduction in boost).
 
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