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Immo
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Immo Nov 14, 6:00pm - #60303 

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2000 Toyota Celica GT

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Tilburg, The Netherlands
hotshots headers <-> backpressures <-> low-end torque

I tried searching, but I can't seem to find a pleasing answer.

Will the hotshots header(s) lose or gain me low-end torque?

From what I understand the exshaust can leave the engine easier, thus gas can get in faster and thus more torque?
Is that correct?
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trog2233
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trog2233 Nov 14, 6:02pm - #60304 

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2004 GMC Canyon Z-71

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Williamsport, PA
Gain...improves low end and mid range thumbsup
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Immo
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Immo Nov 14, 6:59pm - #60305 

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Does anyone have a dyno for it?
I can't seem to find it
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vejita_13
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vejita_13 Nov 14, 8:03pm - #60306 

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2002 Toyota Celica GT

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SACRAMENTO, CA
http://www.nsxprime.com/FAQ/Miscellaneous/exhausttheory.htm


i think it might be the other way around. according to this site, oem exhausts make good low end torque, but aftermaket ones are better for top end power
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glitch
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glitch Nov 14, 8:05pm - #60307 
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Oakland, CA
you will sacrifice low end power to gain more high end

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Immo
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Immo Nov 14, 9:13pm - #60308 

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These are contradicting remarks already smile

Any dynoes on the hotshots header?
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vejita_13
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vejita_13 Nov 15, 1:09am - #60309 

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2002 Toyota Celica GT

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how is that contradictory? did you check the site?
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s355
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s355 Nov 15, 1:38am - #60310 

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2000 Toyota Celica GT

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FACT: equal long tude headers will increase HP due to flow dynamics at higher RPM. Due to the loss of controled back pressure the fuel/air charge hauls ass to fast to give a high denisty charge at low RPM with a result of loss of torque. In the V8 world a two stage header is used, with small tubes out of the head graduating to a larger set before the collector. This allows a medium between the two worlds. The header is to take advantage of the scavening effect of flowing gas to help pull the gases from the other tubes. Long flow headers, tall cams, port and polished heads, big vavles all will give you high RPM HP, but you better come off the line tachin up or you will fall on your face.
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shabu
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shabu Nov 15, 2:19am - #60311 
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I would love to see a dyno for this also - I think a couple of unhappy gts owners have found that not all headers are created equal!
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Elec-FuYu
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Elec-FuYu Nov 15, 3:15am - #60312 
2003 Silver Toyota Celica
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2003 Toyota Celica

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B.C. Coquitlam
one of my friend has his exhaust diameter customized too large...thus his Manual GTS has no power at all...

I am a HID Maniac!!
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Michael Aristide
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Michael Aristide Nov 15, 4:52am - #60313 
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I don't know how many times I've posted this on this site. ohboy Less backpressure isn't the reason why cars lose power. It's the fact that if the diameter is too large, the exhaust gas velocity slows down and cools more, so the exhaust scavenging is reduced. Backpressure is always bad, high exhaust gas velocity is good. thumbsup Wrapping the headers will help that alot.
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Immo
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Immo Nov 15, 10:49am - #60314 

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Originally Posted by vejita_13
how is that contradictory? did you check the site?


I don't mean the site, I mean th remarks here
Some say I will lose low-end, others say I will gain
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Immo
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Immo Nov 15, 10:51am - #60315 

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Originally Posted by Michael Aristide
I don't know how many times I've posted this on this site. ohboy Less backpressure isn't the reason why cars lose power. It's the fact that if the diameter is too large, the exhaust gas velocity slows down and cools more, so the exhaust scavenging is reduced. Backpressure is always bad, high exhaust gas velocity is good. thumbsup Wrapping the headers will help that alot.


Maybe a dumb question

With wrapping the headers you mean put some heat-resistant something around it to keep the heat in?
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Michael Aristide
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Michael Aristide Nov 17, 7:25pm - #60316 
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Miami/Daytona Beach
Originally Posted by Immo
Originally Posted by Michael Aristide
I don't know how many times I've posted this on this site. ohboy Less backpressure isn't the reason why cars lose power. It's the fact that if the diameter is too large, the exhaust gas velocity slows down and cools more, so the exhaust scavenging is reduced. Backpressure is always bad, high exhaust gas velocity is good. thumbsup Wrapping the headers will help that alot.


Maybe a dumb question

With wrapping the headers you mean put some heat-resistant something around it to keep the heat in?


That's correct thumbsup It'll keep the exhaust gasses hotter as they exit the engine improving exhaust scavenging... Might wanna wrap from where the headers start all the way back to the cat... Although some say it causes the metal to deteriorate faster, it'll still last you years to come...
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Rave669
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Rave669 Nov 17, 10:09pm - #60317 

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2002 Toyota Celica

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Lisle, IL
The formula is simple:

the longer the runners on the header the more HP you get, and the more torque you lose.

The Hotshot unit, I have been led to believe, is a shorty header, it should give you good low to midrange power gains, and step up the tourque below 5 grand pretty well.

also there are two types of header 4-1 and 4-2-1

4-1 headers go from four pipes merged straight into one single collector, this type is best for torque gains.

4-2-1 are staged headers, four pipes merge into two, and those two merge into one, this reduces your backpressure a bit and is good for hp gain, but not as good for torque.

the hotshot header for the escort I owned at one pont was a long tube, 4-2-1 header. it flowed really nice, and made nice power from 3K to redline, torque shot up form around 3-5k.

a shorty header with a 4-1 setup will make good power all across the powerband, espescially from 1-5K, and torque will be much improved over stock, especially in the top end of the powerband.

the key is finding a header that has been properly tuned for your specific application. If you need more midrange power and torque, better to go with a hotshot header, but if you need top end power, then going with a full race, long tube 4-2-1 would be good (think trial or Brash Boy header).

Also realize this... a header won't do much unless you have a matched exhaust to flow the extra fumes from your cylinder head. most current cat-backs should do the job. more backpressure for more torque, less for more HP. also, the less restriction you place on your exhaust, the higher in the powerband your gains will be noticable.

if after your header is installed, it feels as if you are losing too much torque, try putting a silencer in your exhaust, or add a resonator upstream (I did this on my escort, the header, hi-flow cat and large exhaust made the car way too loud, and it lost torque. adding a nice, 8" resonator fixed this problem)

hope this helps,

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Michael Aristide
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Michael Aristide Nov 17, 10:17pm - #60318 
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Miami/Daytona Beach
You've got it backwards man. 4-2-1 headers provide better mid-range torque than 4-1 headers. And unless you're running a 3" exhaust or something, an aftermarket component will not make you lose torque, it will just shift it up in the powerband, giving you the sensation of less torque. And you seem knowledgeable enough, but you still don't understand the concept of backpressure vs. exhaust stream velocity... wtf
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Steven
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Steven Nov 17, 10:50pm - #60319 
2001 Spectra Blue Mica Toyota Celica GTS
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I know a >$100 secret for getting back low-mid range torque.
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