Slower after headers and h-pipe?

88GThatchback

Founding Member

Jul 8, 2002

226

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16

Livermore, CA

Mar 11, 2004

#1

• Mar 11, 2004

• #1

I installed some BBK shortie headers and BBK high flow h-pipe. I ran my car at the track last light and ran a 14.7 @ 94mph with a 2.1 60'. Before I installed those I ran a 14.4 @ 96mph with a 2.1 60'. Is it normal to slow down with just exhaust? I have 202hp and 263 ft tq. I would have thought I would run at least as fast as before. If I got a new intake like a performer RPM or something, would that get me a couple tenths? Otherwise I don't see how I could have run so slow.

Thanks,
Clay G.

 

1

10HoleLX

Member

Mar 6, 2004

257

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17

Southern California

Mar 11, 2004

#2

• Mar 11, 2004

• #2

88GThatchback said:

I installed some BBK shortie headers and BBK high flow h-pipe. I ran my car at the track last light and ran a 14.7 @ 94mph with a 2.1 60'. Before I installed those I ran a 14.4 @ 96mph with a 2.1 60'. Is it normal to slow down with just exhaust? I have 202hp and 263 ft tq. I would have thought I would run at least as fast as before. If I got a new intake like a performer RPM or something, would that get me a couple tenths? Otherwise I don't see how I could have run so slow.

Thanks,
Clay G.

Click to expand...

Seems like your engine wants more back pressure.
You'll probably regain that power loss if you reinstall your tailpipes.

 

CobraWannabe

Member

Jul 16, 2003

321

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17

Lancaster, PA

Mar 11, 2004

#3

• Mar 11, 2004

• #3

How long ago was it since you ran before you installed this stuff? It doesn't sound right.

 

F

FordRangerFan17

New Member

Mar 5, 2003

65

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0

Plainfield, Illinois

Mar 11, 2004

#4

• Mar 11, 2004

• #4

you need to open up the intake side of the equation via aftermarket MAF, TB, intake manifold, and preferably a good set of aftermarket heads. the two go hand in hand, there is no real benefit to only working on 1/2 of the equation for power.

 

88GThatchback

Founding Member

Jul 8, 2002

226

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16

Livermore, CA

Mar 12, 2004

#5

• Mar 12, 2004

• #5

The last time I raced before I put on the headers and h-pipe was in september. I put the stuff on in december. Got it dynoed a couple weeks ago. Heres my time slips. Looks like I my 60' is lower on the last run, but right after that i slowed down. I tried shifting at 4800-5000 but got a 14.9 so I tried shifting at 4500 and got 14.8 and a 14.7.

Reaction: .720
I1: 2.165
I2: 6.075
I3: 9.323
I3 MPH: 75.169
I4: 12.105
ET: 14.448
MPH: 96.835

Reaction: .299
I1: 2.138
I2: 6.210
I3: 9.522
I3 MPH: 74.003
I4: 12.372
ET: 14.763
MPH: 94.934

Thanks,
Clay G.

 

maverick0716

Founding Member

Jan 12, 2002

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Chilliwack, BC, Canada

Mar 12, 2004

#6

• Mar 12, 2004

• #6

Try shifting at around 5200

 

N8Miller

I need NOS....make it 2 of the big ones

Founding Member

Jul 26, 2000

2,661

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Kingston, PA, USA

Mar 12, 2004

#7

• Mar 12, 2004

• #7

i agree with fordranger, you need to get that thing flowing some good air. an intake would probably make a good difference. once it starts to flow in fast, then it needs to leave fast.

 

IMissMy93Fox

New Member

Mar 9, 2004

143

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0

Mar 12, 2004

#8

• Mar 12, 2004

• #8

4500 seems like kind of a low shift point to me. I used to shift up around 5500...

 

five_o_stang

New Member

Jan 8, 2004

92

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0

Georgia

Mar 12, 2004

#9

• Mar 12, 2004

• #9

the lack of back pressure is what's causing it.....learned that from a guy that raced for Dugan Racing here in Atlanta...w/o the intake opened up you lose a fair amount of torque...it's normal.....open 'er up and you'll see the difference

 

bmo37

Founding Member

Jun 27, 2001

2,368

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46

New Jersey

Mar 12, 2004

#10

• Mar 12, 2004

• #10

i say backpressure and a loss of torque from switching from a smaller diameter tube to a larger one, you gained more hp but you lost torque thats usually the case with an exhuast swap untill you start modding the h/c/i to gain it back. Remember torque is key not always hp like many people think.

 

willys1

Active Member

Dec 2, 2003

1,004

1

36

New Jersey

Mar 12, 2004

#11

• Mar 12, 2004

• #11

When I put on my shorties,I definitly had a lose in low end torque But when I put on my off rd BBK H-pipe,I noticed a gain in power I still have tail pipes,and I opened up the breathing up front! Im getting a T-moss ported lower,It should breath alot better,but wont over do it,I should keep my low end torque,and good throttle response!

 

90mustangGT

I felt sorry for girls because

Founding Member

Jan 15, 2002

2,773

17

89

Dallas, GA

Mar 12, 2004

#12

• Mar 12, 2004

• #12

My guess is that your exaust on a mostly stock motor like yours too much, because the biggest restriction in the 5.0HO motor is the exaust ports, followed by the lower intake. The exaust ports just can't feed the headers, or should I say that benifits can't be acheved.

Don't get me wrong, I see your setup and it seems yours setting up a wicked car. Just keep on building, your doing the right things. I see a you've built a good ignition system and quite a suspension, now exaust, just keep on it, it will all work out very nicley in the end.