Another Header Question
Thread Starter
Burning Brakes
Joined: Dec 1999
Posts: 1,104
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Another Header Question
Are Headers really worth it! I know there has been endless discussions here including claimed great increases in HP (seems especially relavant with major engine mods), but do you really feel it on a basically stock car that has intake and exhaust done?
I'm considering a Supercharger in the future and don't know if it is worth doing headers now. I know headers would be good with the supercharger, but on the basically stock car, I don't know. Any thoughts?
I'm considering a Supercharger in the future and don't know if it is worth doing headers now. I know headers would be good with the supercharger, but on the basically stock car, I don't know. Any thoughts?
Le Mans Master
Joined: Oct 2001
Posts: 5,577
Likes: 3
From: Southern Maryland Maryland
Re: Another Header Question (fxrhm)
I definitely think headers are worth it just make sure after you install your headers your not running overly rich or lean to offset the gain in HP/Tq. Good luck. BTW A cam is better bang for the buck. :crazy:
[Modified by Phil97SVT, 10:59 PM 3/6/2002]
[Modified by Phil97SVT, 10:59 PM 3/6/2002]
Drifting
Joined: Apr 2001
Posts: 1,773
Likes: 0
From: Norman Oklahoma
Re: Another Header Question (fxrhm)
Since you plan on doing more mods in the future I think headers would be a good investment but there are other things that you would feel more like a cam. Then a good set of headers would really compliment your car
Jerry
Jerry
Thread Starter
Burning Brakes
Joined: Dec 1999
Posts: 1,104
Likes: 0
Re: Another Header Question (Phil97SVT)
I thought the pcm adjusts for the headers :confused:
Would a cam do much without heads?
Would a cam do much without heads?
I definitely think headers are worth it just make sure after you install your headers your not running overly rich or lean to offset the gain in HP/Tq. Good luck. BTW A cam is better bang for the buck. :crazy:
[Modified by Phil97SVT, 10:59 PM 3/6/2002]
[Modified by Phil97SVT, 10:59 PM 3/6/2002]
Pro
Joined: May 2000
Posts: 654
Likes: 0
From: Dallas Texas
Re: Another Header Question (fxrhm)
I have been kicking this around since I have had my car. The headers are $1,000 +. Then about $300 to have them put on. I figure around $1,500 invested in headers total. These headers prices really make me mad, I have had headers on just about every car I have owned. The most I ever paid for a set was $400. But of course I was not putting these on a vette. Its just not worth it UNLESS you are doing heads,cam, or in your case a supercharger. If $$ is no object then go for it. But if you are like me , its just not worth a few hp for the amount of $$.
Good luck !
Good luck !
Pro
Joined: Oct 2000
Posts: 545
Likes: 1
From: Charlotte NC
Re: Another Header Question (Anthony Cleveland)
I disagree. Headers are a definite "must" on any engine with mods, w/o mods they are the first step towards hp gains. If you install a cam, this alone will be money poorly spent without headers and a decent aftermarket exhaust system. In other words if you go with a cam you NEED to do these other mods. A good set of headers can gain you up to 20rwhp alone. That, is bang for the buck! My two cents worth.
Instructor
Joined: Mar 2002
Posts: 239
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From: Fredericksburg VA
Re: Another Header Question (racetchr)
Stock performance rarely gets all of the horsepower potential out of the cylinder heads. An increase in cam timing can push the intake toward its flow potential. The potential of the exhaust port will never be realized without the scavenging benefit from headers. A dyno test will show the horsepower curve will be chopped off flat at the top, and will sign off early because of exhaust contamination. Headers yank the cylinder pressure down low during valve overlap at high RPM, allowing you to use that horsepower hidden on the upper side of the peak horsepower RPM. Cam it out, get the right headers, and gear it to rev straight through the horsepower band.
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Melting Slicks
Joined: Feb 2002
Posts: 3,179
Likes: 13
From: Coal Valley IL
CI 4-7, 9 & 10 Veteran
Re: Another Header Question (HeaderDesign.com)
I just got my car back Tuesday after installing JBA silver ceramic shorties, Corsa Pace car exhaust and Corsa X-pipe. I have not had it dyno'd yet because I just took it out of storage for the appointment and still had old gas in it. I could definately feel a difference in performance when I laid into it taking it home. It was a definite improvement. The shorties allowed me to keep the Cats and all factory emmisions. I have an ATI P1SC on order. Definately get some headers even if you are going to wait on further mods.
Safety Car
Joined: Oct 1999
Posts: 3,514
Likes: 0
Re: Another Header Question (JTE)
I'm getting some for sure, just deciding between the LG's (expensive) or the TTS. For me either one will remove the precats which is critical. Those drain away HP. I am looking to get at least 15rwhp and 15 rwt. I think that's worthwhile for sure.
Joe
Joe
Thread Starter
Burning Brakes
Joined: Dec 1999
Posts: 1,104
Likes: 0
Re: Another Header Question (HeaderDesign.com)
What about at the low end - will headers be efficient without a cam change?
Stock performance rarely gets all of the horsepower potential out of the cylinder heads. An increase in cam timing can push the intake toward its flow potential. The potential of the exhaust port will never be realized without the scavenging benefit from headers. A dyno test will show the horsepower curve will be chopped off flat at the top, and will sign off early because of exhaust contamination. Headers yank the cylinder pressure down low during valve overlap at high RPM, allowing you to use that horsepower hidden on the upper side of the peak horsepower RPM. Cam it out, get the right headers, and gear it to rev straight through the horsepower band.
Instructor
Joined: Mar 2002
Posts: 239
Likes: 0
From: Fredericksburg VA
Re: Another Header Question (fxrhm)
Divide your peak horsepower RPM by 2. If your driving style requires good full-throttle performance below this RPM, then high-performance manifolds, shorty headers, or interference headers are your best choice. If you need best performance above this RPM, then a long-tube header is the best choice regardless of camshaft selection.
To get best low-end performance with long-tube headers, make sure they are not too big or too short for your application. The diameter of the collector should not be oversized either. Race headers are designed so that the header is in tune at RPMs above the peak horsepower RPM, but they compromise the low-end. Fat horsepower curves win races. For the street and occasional race use you should use headers that are in tune throughout the entire midrange, don't help or hurt the bottom end, and give good horsepower.
To get best low-end performance with long-tube headers, make sure they are not too big or too short for your application. The diameter of the collector should not be oversized either. Race headers are designed so that the header is in tune at RPMs above the peak horsepower RPM, but they compromise the low-end. Fat horsepower curves win races. For the street and occasional race use you should use headers that are in tune throughout the entire midrange, don't help or hurt the bottom end, and give good horsepower.
Thread Starter
Burning Brakes
Joined: Dec 1999
Posts: 1,104
Likes: 0
Re: Another Header Question (HeaderDesign.com)
Rodney,
Great info, I appreciate that. So do you know if the following headers are in the low, mid or high efficiency range?
TPIS Long Tube
Belanager Long Tube
B&B Shorties?
Great info, I appreciate that. So do you know if the following headers are in the low, mid or high efficiency range?
TPIS Long Tube
Belanager Long Tube
B&B Shorties?
Instructor
Joined: Mar 2002
Posts: 239
Likes: 0
From: Fredericksburg VA
Re: Another Header Question (fxrhm)
No I don't. You need to ask them what the primary header pipe length and inside diameter are, and what the collector body inside diameter is. You can make the collector length to the x or h-pipe correct at the exhaust shop. Shorty headers are in the low and lower midrange unless the pipes are oversized, then there in the no-range.
Also give me your best estimate of your flywheel horsepower and and peak horsepower RPM, as well as all your engine specs including comp. ratio. What RPM do you consider low-end?
Also give me your best estimate of your flywheel horsepower and and peak horsepower RPM, as well as all your engine specs including comp. ratio. What RPM do you consider low-end?
Le Mans Master
Joined: Aug 2000
Posts: 5,294
Likes: 2
From: Suffolk, Long Island NY
Re: Another Header Question (HeaderDesign.com)
Shorty headers are in the low and lower midrange unless the pipes are oversized, then there in the no-range.
Thanks,
Thread Starter
Burning Brakes
Joined: Dec 1999
Posts: 1,104
Likes: 0
Re: Another Header Question (HeaderDesign.com)
Dynoed at 316.7 RWHP, which equates to (at least I think, divide RWHP by .85?) 372.6 HP at the crank (is that the same as at the flywheel?). HP peaked at about 4600 RPM.
Engine c/r = 10.1:1, which is standard on a '00 C-5, 5.7L V-8.
I consider low RPM about 3,000 RPM's. Thanks for the info - it's helping me think through what to do next.
Engine c/r = 10.1:1, which is standard on a '00 C-5, 5.7L V-8.
I consider low RPM about 3,000 RPM's. Thanks for the info - it's helping me think through what to do next.
Also give me your best estimate of your flywheel horsepower and and peak horsepower RPM, as well as all your engine specs including comp. ratio. What RPM do you consider low-end?
Instructor
Joined: Mar 2002
Posts: 239
Likes: 0
From: Fredericksburg VA
Re: Another Header Question (BLOWNGS)
Shorty headers do a good job of moving exhaust gas at all engine speeds. They will dampen exhaust pressure waves during the lower-RPM, heavy-throttle condition, which is a good thing. Long-tube headers go in and out of tune at low RPM, and the pressure waves are strong. So for low-RPM, heavy-throttle the shorties win. For low-RPM light throttle the long-tubes are best, unless they are grossly oversized. For the midrange and high-RPM at any throttle position, correctly sized long-tube headers are much better than shorties because of the intense scavenging wave present at the exhaust valve during overlap. Engine performance with shorties and manifolds can be improved with careful location of the crossover.
Instructor
Joined: Mar 2002
Posts: 239
Likes: 0
From: Fredericksburg VA
Re: Another Header Question (fxrhm)
Dynoed at 316.7 RWHP, which equates to (at least I think, divide RWHP by .85?) 372.6 HP at the crank (is that the same as at the flywheel?). HP peaked at about 4600 RPM.
Engine c/r = 10.1:1, which is standard on a '00 C-5, 5.7L V-8.
fxrhm - with the exhaust manifolds, cats and mufflers, 373hp at 4600RPM sound like a resonable estimate. I think with headers that the peak horsepower RPM would increase. I conservatively estimated the peak horsepower RPM with headers at 4750. Add a little longer cam and it could quickly go up to 5000. The header would also need to change.
Using 373hp at 4750RPM and 10:1 compression, the optimal primary header pipe size falls between 1 5/8 and 1 3/4. A good street performance header with the 6 speed transmission would be 1 5/8" by 38 1/2" primaries, and 2 1/2" by 15" collectors measured from the end of the primary pipes to the x or h-pipe junction. This header would give you good top-end power and a shift point of about 5000. The entire midrange would be excellent, and throttle response and overall drivablilty would be excellent. An all-out race header for this stock engine would have different dimensions in order to extend the RPM range.
Engine c/r = 10.1:1, which is standard on a '00 C-5, 5.7L V-8.
fxrhm - with the exhaust manifolds, cats and mufflers, 373hp at 4600RPM sound like a resonable estimate. I think with headers that the peak horsepower RPM would increase. I conservatively estimated the peak horsepower RPM with headers at 4750. Add a little longer cam and it could quickly go up to 5000. The header would also need to change.
Using 373hp at 4750RPM and 10:1 compression, the optimal primary header pipe size falls between 1 5/8 and 1 3/4. A good street performance header with the 6 speed transmission would be 1 5/8" by 38 1/2" primaries, and 2 1/2" by 15" collectors measured from the end of the primary pipes to the x or h-pipe junction. This header would give you good top-end power and a shift point of about 5000. The entire midrange would be excellent, and throttle response and overall drivablilty would be excellent. An all-out race header for this stock engine would have different dimensions in order to extend the RPM range.