Cat Hpipe VS Stock VS OffRoad

Skyman · 02-13-2002, 03:55 AM

Well when I changed my car from the stock Hpipe to the offroad I got HUGE Gains. It was one of the very last mods I did, so I figured the stock Hpipe was kinda clogged and thats why it made such a huge difference.

Well I just put on a MAC Hi-Flow Cat H-pipe and my car is wayyy quieter! Which is alright, but I lost tons of power.

I DONT GET IT!??!

Everyone had me convinced I would loose maybe maybe 5hp.

It definatly lost about 30-40 hp on the butt dyno. It doesnt feel alot faster than when I had the stock catalytic H pipe on.

It used to just annihilate the tires going into 2nd gear for 30-40 feet, now it just spins em for about 5-10feet.

Is there any explanation for this?

HELP, I need more HP. Im going to have to do something drastic, the car is not what it used to be.

Skyler

Skyman · 02-13-2002, 06:31 AM

Well I just went and ran my cousins 1968 Mustang.

He traps 100mph at the track and I would always just pull like crazy on him.

Guess what.

WE RAN DEAD EVEN TONIGHT.

Neither one of us could pull either way.

So I've lost 7mph atleast w/ this H-pipe, wtf gives.............

Sky

byrnech · 02-13-2002, 06:42 AM

maybe the MAC "high flow" cats aren't as high flow as they are supposed to be. Why are you changing over to cats? For emissions? I have swapped out a set of high flow cats for my off road before, and it wasn't that bad. I think they are bbk or something. But it did make it a bit quieter. I should be back in cali in about a month or two, I hope to see you at carlsbad when I get back to the states. Later, -Chris

Rick 91GT · 02-13-2002, 08:27 AM

Sky- Long time no talk, hope all is well besides this H-Pipe issue.
We run the MAC High Flow cats on Dads 93 Cobra and they flow pretty good, ran much better and picked up mph over a stock H-pipe, his only had 30K on it. He traps 119 with the blower on it so I say get it to the track and see how it runs, you may need a different tune.

They say the Off Roads are worth 10-15hp depending on the set-up, more in the upper rpms. Why did you put it back on, just for testing or as a precaution, I heard they are cracking down out there.

Take Care,

Rick

Skyman · 02-14-2002, 01:50 PM

Im thinking they are clogged?

I am running dead even with a 100mph trapping car.

The power is gone, it doesnt even burn the tires into 2nd gear anymore.

I don't understand how it could possibly rob that much power, is there a chance they came clogged??

Is MAC ****!?

Skyler

88COBRA · 02-14-2002, 09:56 PM

Hey Skyman....

My friend went from off-road to the MAC cat pipe and he did not notice a difference at all.

I myself will be going with a MAC cat pipe. Their pipes are quality pieces for sure.

If you can, get to a dyno, I would like to know.

I know what you need....a supercharger

Let us know what happens.

jonnyk · 02-14-2002, 11:46 PM

How long has it been on the car? Has the computer had time to adjust? It will give the O2's much different readings now...

Skyman · 02-15-2002, 03:22 AM

Hey Rick! Yea, how are things, man your car keeps gettin faster, mine seems to be getting slower and less and less fun to drive. Man Im about ready to get rid of it.

Its definatly lost a LOT of power, no need to hit a dyno, I know my car well.

I am going to check everything out under the car tomrrow, tune it up and reset the comptuer, after that Im going to get a bassani pipe and see what happens.

Im really frustrated and pissed.

Skyler

PKRWUD · 02-15-2002, 05:59 AM

Sky-
With a vacuum gauge, there are two easy tests you can run to determine if your exhaust is restricted (cats clogged).

First test:
1) Attach vacuum gauge to manifold vacuum source.
2) Observe vacuum at idle.
3) Snap throttle to WOT and release, while watching the gauge.

The vacuum gauge should drop to almost zero when you hit WOT. When the throttle snaps closed immediately after, the vacuum should read 4" to 6" higher than what it did at idle. It should then settle back at the same reading it was at idle before the WOT snap. This whole exchange should go from idle reading to idle reading in 2-3 seconds, tops. If it takes longer for the gauge to return to the same idle reading, your exhaust is restricted. The longer it takes, the worse the restriction.

Second test:
1) Attach vacuum gauge to manifold vacuum source.
2) Warm up engine.
3) Observe vacuum at idle.
4) Leave engine idling for 10 minutes. Do not touch anything on the car during this time. In fact, go inside and fix some coffee.
5) After 10 minutes, observe the vacuum.

If the vacuum is the same or higher, you don't have any resctrictions. If the vacuum gauge has dropped, you do have a restriction. The more it drops, the greater the restriction. If it drops 1" or more, you have a serious restriction. 2" or more and you might as well have the exhaust welded shut. Keep in mind that a rich exhaust will clog up cats in a hurry.

86GT · 02-15-2002, 01:13 PM

I noticed a loss when I switched from shorties/off-road to long tube/mac cat pipe. It was the same thing for me, wouldn't pull nearly as hard. I've never tracked my car with the this combo with shorties/off road, only long tubes. I trap 107-108 this way, and I feel that with the offroad it's faster. Must be MAC's quality biting us in the butt again. I'm getting an off-road pipe for the long tubes soon, and then I'll know for sure what the difference is.

Chevyguy · 02-15-2002, 05:10 PM

Anyone running the BBK or Bassani Cat pipe for long or short tubes?? Wonder if they have similar experience?

stock89 · 02-15-2002, 11:31 PM

This guy I know just took a stock H and hollowed out the cats by bute force beating and a long metal rod. Makes it at least look like it has cats if someone does stick there head under there, and is a lot cheaper to buy a used H pipe than an OR. Any ideas on how well this thing will perform??? In theory I would say better....

Bad89stang · 02-16-2002, 02:47 AM

Skyler, I have only off-road H, flows, CAI, and 3.55 gears and my car smokes 1st and spins all the way through 2nd. Sounds like the MAC H-pipe took about 30ft/lbs of torque. Just guessing.

shadowblue89 · 02-16-2002, 12:51 PM

Hey Skyman,
I also have just recently put on the Mac High-flow cat h-pipe. My experience very different though. I actually gain a lot of low end and did not notice a difference on the top end. I had a mac off road h-pipe before hand.

Skyman · 02-16-2002, 02:26 PM

GOOD NEWS!

Well I reset my computer by taking the battery off for a half hour and hooking it back up.

THE CAR PULLS LIKE CRAZY AGAIN!

I guess it had to adjust to the new H-pipe.

Pretty interesting huh? Well I am excited now. It is jurking and bucking a little bit in the low rpms.

Im sure I can tune those bugs out though.

Skyler

jimberg · 02-17-2002, 02:54 PM

I was going to say that I had a similar experience with going from my BBK hi-flow h-pipe to an off-road x-pipe. I thought I made a huge mistake since it was so sluggish. Resetting the computer was the trick.

I hope you have your air pump hooked up to those cats. If you don't, they won't work as well and will get clogged in no time.

02-13-2002, 03:55 AM	#1
Skyman I need 110mph Trap Speed! Join Date: Feb 1999 Location: So, CA Posts: 4,315	Cat Hpipe VS Stock VS OffRoad Well when I changed my car from the stock Hpipe to the offroad I got HUGE Gains. It was one of the very last mods I did, so I figured the stock Hpipe was kinda clogged and thats why it made such a huge difference. Well I just put on a MAC Hi-Flow Cat H-pipe and my car is wayyy quieter! Which is alright, but I lost tons of power. I DONT GET IT!??! Everyone had me convinced I would loose maybe maybe 5hp. It definatly lost about 30-40 hp on the butt dyno. It doesnt feel alot faster than when I had the stock catalytic H pipe on. It used to just annihilate the tires going into 2nd gear for 30-40 feet, now it just spins em for about 5-10feet. Is there any explanation for this? HELP, I need more HP. Im going to have to do something drastic, the car is not what it used to be. Skyler __________________ 2001 BMW M3 6spd 12.79@108 RIP ---- 1993 Notch w/ 98 4V 4.6 Fasttt... -1989 Saleen Mustang #406- 12.32@109 -1999 Black Cobra Coupe- JBA Shorties, Bassani Cat-X, Magnaflow 3", Pulleys, 85mm Pro-M, Ported Intake, Soild Rear w/ 4.30s, Tubular Front End, X2C arms, 13lb batt, few others.

02-13-2002, 06:31 AM	#2
Skyman I need 110mph Trap Speed! Join Date: Feb 1999 Location: So, CA Posts: 4,315	Well I just went and ran my cousins 1968 Mustang. He traps 100mph at the track and I would always just pull like crazy on him. Guess what. WE RAN DEAD EVEN TONIGHT. Neither one of us could pull either way. So I've lost 7mph atleast w/ this H-pipe, wtf gives............. Sky __________________ 2001 BMW M3 6spd 12.79@108 RIP ---- 1993 Notch w/ 98 4V 4.6 Fasttt... -1989 Saleen Mustang #406- 12.32@109 -1999 Black Cobra Coupe- JBA Shorties, Bassani Cat-X, Magnaflow 3", Pulleys, 85mm Pro-M, Ported Intake, Soild Rear w/ 4.30s, Tubular Front End, X2C arms, 13lb batt, few others.

02-13-2002, 06:42 AM	#3
byrnech Registered Member Join Date: Jun 2001 Location: Anderson, TX. Posts: 166	maybe the MAC "high flow" cats aren't as high flow as they are supposed to be. Why are you changing over to cats? For emissions? I have swapped out a set of high flow cats for my off road before, and it wasn't that bad. I think they are bbk or something. But it did make it a bit quieter. I should be back in cali in about a month or two, I hope to see you at carlsbad when I get back to the states. Later, -Chris __________________ 331 10:1, AFR 185's, TFS-R intake

02-13-2002, 08:27 AM	#4
Rick 91GT Procharged! Join Date: May 1999 Location: Hanover, PA Posts: 1,539	Sky- Long time no talk, hope all is well besides this H-Pipe issue. We run the MAC High Flow cats on Dads 93 Cobra and they flow pretty good, ran much better and picked up mph over a stock H-pipe, his only had 30K on it. He traps 119 with the blower on it so I say get it to the track and see how it runs, you may need a different tune. They say the Off Roads are worth 10-15hp depending on the set-up, more in the upper rpms. Why did you put it back on, just for testing or as a precaution, I heard they are cracking down out there. Take Care, Rick __________________ *D/R 10108 NMRA Drag Radial, 25.5 chassis, F1R* *Check out RNH Performance Performance Engines and Custom Fabrication.* *From Mild to Wild we can build what you want, when you want it.* FOR SALE Stainless Steel Torque Box Supports

02-14-2002, 01:50 PM	#5
Skyman I need 110mph Trap Speed! Join Date: Feb 1999 Location: So, CA Posts: 4,315	Im thinking they are clogged? I am running dead even with a 100mph trapping car. The power is gone, it doesnt even burn the tires into 2nd gear anymore. I don't understand how it could possibly rob that much power, is there a chance they came clogged?? Is MAC **!? Skyler __________________ 2001 BMW M3 6spd 12.79@108 RIP ---- 1993 Notch w/ 98 4V 4.6 Fasttt... -1989 Saleen Mustang #406- 12.32@109 -1999 Black Cobra Coupe-** JBA Shorties, Bassani Cat-X, Magnaflow 3", Pulleys, 85mm Pro-M, Ported Intake, Soild Rear w/ 4.30s, Tubular Front End, X2C arms, 13lb batt, few others.

02-14-2002, 09:56 PM	#6
88COBRA STANGPOWER.COM Join Date: Jun 1999 Location: Ontario, Canada Posts: 1,045	Hey Skyman.... My friend went from off-road to the MAC cat pipe and he did not notice a difference at all. I myself will be going with a MAC cat pipe. Their pipes are quality pieces for sure. If you can, get to a dyno, I would like to know. I know what you need....a supercharger Let us know what happens. __________________ My WebSites: VortechPower.com - Brand new site for Vortech users! NOVIPOWER.COM - Devoted to the performance of the NOVI supercharger STANGPOWER.COM - A small community based in Canada for Mustangs *MORE WebSites Coming soon* PLEASE NOTE: I am not an affiliate (nor do I work for) any Mustang parts retailers - I create informational Mustang WebSites

02-14-2002, 11:46 PM	#7
jonnyk Being stroked is great Join Date: Oct 1998 Location: Alberta, Canada Posts: 772	How long has it been on the car? Has the computer had time to adjust? It will give the O2's much different readings now... __________________ Novi 2000 now spinning off the snout of the 331... Mods Pics

02-15-2002, 03:22 AM	#8
Skyman I need 110mph Trap Speed! Join Date: Feb 1999 Location: So, CA Posts: 4,315	Hey Rick! Yea, how are things, man your car keeps gettin faster, mine seems to be getting slower and less and less fun to drive. Man Im about ready to get rid of it. Its definatly lost a LOT of power, no need to hit a dyno, I know my car well. I am going to check everything out under the car tomrrow, tune it up and reset the comptuer, after that Im going to get a bassani pipe and see what happens. Im really frustrated and pissed. Skyler __________________ 2001 BMW M3 6spd 12.79@108 RIP ---- 1993 Notch w/ 98 4V 4.6 Fasttt... -1989 Saleen Mustang #406- 12.32@109 -1999 Black Cobra Coupe- JBA Shorties, Bassani Cat-X, Magnaflow 3", Pulleys, 85mm Pro-M, Ported Intake, Soild Rear w/ 4.30s, Tubular Front End, X2C arms, 13lb batt, few others.

02-15-2002, 05:59 AM	#9
PKRWUD Junior Member Join Date: Mar 1999 Location: Ventura, California Posts: 8,981	Sky- With a vacuum gauge, there are two easy tests you can run to determine if your exhaust is restricted (cats clogged). First test: 1) Attach vacuum gauge to manifold vacuum source. 2) Observe vacuum at idle. 3) Snap throttle to WOT and release, while watching the gauge. The vacuum gauge should drop to almost zero when you hit WOT. When the throttle snaps closed immediately after, the vacuum should read 4" to 6" higher than what it did at idle. It should then settle back at the same reading it was at idle before the WOT snap. This whole exchange should go from idle reading to idle reading in 2-3 seconds, tops. If it takes longer for the gauge to return to the same idle reading, your exhaust is restricted. The longer it takes, the worse the restriction. Second test: 1) Attach vacuum gauge to manifold vacuum source. 2) Warm up engine. 3) Observe vacuum at idle. 4) Leave engine idling for 10 minutes. Do not touch anything on the car during this time. In fact, go inside and fix some coffee. 5) After 10 minutes, observe the vacuum. If the vacuum is the same or higher, you don't have any resctrictions. If the vacuum gauge has dropped, you do have a restriction. The more it drops, the greater the restriction. If it drops 1" or more, you have a serious restriction. 2" or more and you might as well have the exhaust welded shut. Keep in mind that a rich exhaust will clog up cats in a hurry. __________________ Webmaster: Rice Haters Club Jim Porter Racing Peckerwoods Pit Stop Support Your Local RED & WHITE!

02-15-2002, 01:13 PM	#10
86GT Sniffed too much n20 Join Date: Oct 1998 Location: Ont, Canada Posts: 1,018	I noticed a loss when I switched from shorties/off-road to long tube/mac cat pipe. It was the same thing for me, wouldn't pull nearly as hard. I've never tracked my car with the this combo with shorties/off road, only long tubes. I trap 107-108 this way, and I feel that with the offroad it's faster. Must be MAC's quality biting us in the butt again. I'm getting an off-road pipe for the long tubes soon, and then I'll know for sure what the difference is.

02-15-2002, 05:10 PM	#11
Chevyguy Backyard Mechanic/Chemist Join Date: Feb 2001 Location: Acton MA USA Posts: 435	Anyone running the BBK or Bassani Cat pipe for long or short tubes?? Wonder if they have similar experience? __________________ 2001 Crown Vic Maurader Airbox/MAF, DR chip Edel IAS shocks Single exhaust :wtf: 93 P-71 Vic interceptor Backup car now 90 5.0 LX Notch SOLD 74 Chevy Laguna type S-3 454 under construction Currently apart undergoing bodywork.

02-15-2002, 11:31 PM	#12
stock89 Registered Member Join Date: Oct 2001 Location: Mannheim, Germany Posts: 124	Stock h pipe hollowed out? This guy I know just took a stock H and hollowed out the cats by bute force beating and a long metal rod. Makes it at least look like it has cats if someone does stick there head under there, and is a lot cheaper to buy a used H pipe than an OR. Any ideas on how well this thing will perform??? In theory I would say better....

02-16-2002, 02:47 AM	#13
Bad89stang Registered Member Join Date: Aug 2001 Location: Ft. Worth, TX Posts: 456	Serious torque loss.... Skyler, I have only off-road H, flows, CAI, and 3.55 gears and my car smokes 1st and spins all the way through 2nd. Sounds like the MAC H-pipe took about 30ft/lbs of torque. Just guessing. __________________ You're gonna need your seatbelt

02-16-2002, 12:51 PM	#14
shadowblue89 Registered Member Join Date: Jan 1999 Location: Las Vegas NV Posts: 286	Hey Skyman, I also have just recently put on the Mac High-flow cat h-pipe. My experience very different though. I actually gain a lot of low end and did not notice a difference on the top end. I had a mac off road h-pipe before hand. __________________ Charlie 89 GT 5spd

02-16-2002, 02:26 PM	#15
Skyman I need 110mph Trap Speed! Join Date: Feb 1999 Location: So, CA Posts: 4,315	GOOD NEWS! Well I reset my computer by taking the battery off for a half hour and hooking it back up. THE CAR PULLS LIKE CRAZY AGAIN! I guess it had to adjust to the new H-pipe. Pretty interesting huh? Well I am excited now. It is jurking and bucking a little bit in the low rpms. Im sure I can tune those bugs out though. Skyler __________________ 2001 BMW M3 6spd 12.79@108 RIP ---- 1993 Notch w/ 98 4V 4.6 Fasttt... -1989 Saleen Mustang #406- 12.32@109 -1999 Black Cobra Coupe- JBA Shorties, Bassani Cat-X, Magnaflow 3", Pulleys, 85mm Pro-M, Ported Intake, Soild Rear w/ 4.30s, Tubular Front End, X2C arms, 13lb batt, few others.

02-17-2002, 02:54 PM	#16
jimberg Registered Member Join Date: Oct 1998 Location: Rogers, MN Posts: 2,089	I was going to say that I had a similar experience with going from my BBK hi-flow h-pipe to an off-road x-pipe. I thought I made a huge mistake since it was so sluggish. Resetting the computer was the trick. I hope you have your air pump hooked up to those cats. If you don't, they won't work as well and will get clogged in no time. __________________ 351W 89 Mustang GT Convertible

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