Disappointed Dyno

[JEWC_Motorsports]

The cats are in, but the tune is for an O/R H pipe. Bama said that I only needed the Cats in the tune if I was installing the rear 02 sensors.

Can someone explain to me how this could be ok for your cats? Over time wont this hurt them since the rear 02's are what add fuel and help them burn off the contaminants? Plugged cats=drop in hp=blown motor???

 

[HellsBells]

Can someone explain to me how this could be ok for your cats? Over time wont this hurt them since the rear 02's are what add fuel and help them burn off the contaminants? Plugged cats=drop in hp=blown motor???

You're right.

If his tune is overly rich, then it will damage the cats. If his tune is overly lean, it will also damage his cats. Now, whether his cats will ever get so damaged that it will clog and blow the motor is a different story.

Also, my car made 300whp and 308tq with: intake, hot rods, o/r pipe, mufflers, 93 BAMA race tune.

 

[Cammed 05]

My car made 331/327 with Mac lt's, o/r h, hot rods, jlt, and a Bama 93 tune with 4.10's. Only went up to a whopping 385 with a 125 shot. Then again my buddy with same mods minus the spray but frpp manifold, pullies, and throttle body. He made 318 on the same dyno went and ran on another dyno and pulled 347 with out the hotrods. No way his car lost 30hp lmao.

 

[Huck]

You're right.

If his tune is overly rich, then it will damage the cats. If his tune is overly lean, it will also damage his cats. Now, whether his cats will ever get so damaged that it will clog and blow the motor is a different story.

Also, my car made 300whp and 308tq with: intake, hot rods, o/r pipe, mufflers, 93 BAMA race tune.

I asked Bama about the rear 02 sensors and the impact of hot having any. I was told that the only purpose was for emission testing and that there was absolutely no impact to the engine. I have the front sensors (in the headers) but none after/in the cat.

 

[91boost]

When were you there? I was there and had mine on the dyno today to. Mine made 251 hp and 256 tq. I have sct tuner cold air and axle backs through a auto.

 

[Newman]

That does sound low, def have a few left revving it more. I must be lucky with my set up putting 350hp to the wheels on 305-35-20's.

AND that was with 2 different cams in my car. YES I SAID 2 DIFFERENT CAMS.(one of each)

 

[Huck]

When were you there? I was there and had mine on the dyno today to. Mine made 251 hp and 256 tq. I have sct tuner cold air and axle backs through a auto.

My time was 11:15

 

[Greg Hazlett]

When were you there? I was there and had mine on the dyno today to. Mine made 251 hp and 256 tq. I have sct tuner cold air and axle backs through a auto.

WOW..that is really low....my 2010 automatic made almost that bone stock with 300 miles on it!

 

[Ampire]

With just a C&L intake and a tune I made 303/310 on JPC's dyno. You would pick up another 30 on top of that with LT and cams, so you are definitely reading low.

What is your 1/4 et? That will tell you more than any dyno.

 

[HellsBells]

I asked Bama about the rear 02 sensors and the impact of hot having any. I was told that the only purpose was for emission testing and that there was absolutely no impact to the engine. I have the front sensors (in the headers) but none after/in the cat.

Right. No impact to the engine, but it will fry your cats overtime. The rear o2 checks for catalyst efficiency and adjusts the tune to run richer/leaner to keep the cats at optimum temperature. Too cold and they don't work as well for emissions. Too hot and they will melt.

 

[Thekid760]

What was your AFR?

 

[Huck]

With just a C&L intake and a tune I made 303/310 on JPC's dyno. You would pick up another 30 on top of that with LT and cams, so you are definitely reading low.

What is your 1/4 et? That will tell you more than any dyno.

1/4 et? Assume this is a racing time? My last race was 1975 in a 66 Mustang on Woodward Ave (home of the Dream Cruise). I am in the over 50 crown and have never raced my car. Don't have the reflexes for it anymore.

 

[Huck]

Right. No impact to the engine, but it will fry your cats overtime. The rear o2 checks for catalyst efficiency and adjusts the tune to run richer/leaner to keep the cats at optimum temperature. Too cold and they don't work as well for emissions. Too hot and they will melt.

Wow, would have been nice to get this info from Bama when I was asking all my questions. Looks like I need to order the Pypes Cats with the bung hole. Damn, I just had my cats welded in to seal a small leak.

 

[Huck]

What was your AFR?

I don't know what AFR is. If it has anything to do with racing see my previous post.

 

[JeremyH]

Right. No impact to the engine, but it will fry your cats overtime. The rear o2 checks for catalyst efficiency and adjusts the tune to run richer/leaner to keep the cats at optimum temperature. Too cold and they don't work as well for emissions. Too hot and they will melt.

Call me crazy but im pretty darn sure the rear o2's on the 3v do not do this like the coyote does. They are merely a cat detector but have no way to impact the tune iirc. But I agree if you have cats no reason to have the rear o2's off, not that it would effect the tune either way though.

 

[HellsBells]

Call me crazy but im pretty darn sure the rear o2's on the 3v do not do this like the coyote does. They are merely a cat detector but have no way to impact the tune iirc. But I agree if you have cats no reason to have the rear o2's off, not that it would effect the tune either way though.

I know most modern cars do this, not just the coyotes, but if anyone knows for sure I'll let them chime in. My thinking is that if they didn't do this, all cars would get a lot more issues with their cats going bad.

 

[BruceH]

Call me crazy but im pretty darn sure the rear o2's on the 3v do not do this like the coyote does. They are merely a cat detector but have no way to impact the tune iirc. But I agree if you have cats no reason to have the rear o2's off, not that it would effect the tune either way though.

I've run factory cats the entire time I've owned my car except for one week of high flow cats.

If I don't turn the rear o2 sensors off they will override the fuel tables in open loop and will force open loop during closed loop pedal position during normal driving in order to cool the cats. I have observed it on the dyno during open loop.

I've had them turned off for at least 3 years of use and my factory cats are still going strong. I am looking for a local set to put in the attic just in case however.

 

[Ampire]

I don't know what AFR is. If it has anything to do with racing see my previous post.

Air fuel ratio. This tells you whether the engine is rich or lean and is a good indication of safe power potential. AFR is detected by a wideband oxygen sensor in the exhaust system or by a sniffer on the tail pipe. Too rich and it won't produce as much power. Too lean and it will knock. Ideal (safe but still performing) AFR on a naturally aspirated engine is usually around 13.

 

[JeremyH]

I've run factory cats the entire time I've owned my car except for one week of high flow cats.

If I don't turn the rear o2 sensors off they will override the fuel tables in open loop and will force open loop during closed loop pedal position during normal driving in order to cool the cats. I have observed it on the dyno during open loop.

I've had them turned off for at least 3 years of use and my factory cats are still going strong. I am looking for a local set to put in the attic just in case however.

It forces open loop during closed loop?

I think I understand what you are trying to say though, based on that I would def turn them off, as long as your tune is spot on I dont see it being an issue, other than the fact that wot stoich is richer on force induction so the cats will be cooler anyway I would think, then exhuast pressure and heat go up too.

 

[BruceH]

It forces open loop during closed loop?

I think I understand what you are trying to say though, based on that I would def turn them off, as long as your tune is spot on I dont see it being an issue, other than the fact that wot stoich is richer on force induction so the cats will be cooler anyway I would think, then exhuast pressure and heat go up too.

Stoichiometric is the ratio of air to fuel to achieve 1 labda. The lambda changes during open loop.

You can call it whatever you want but my books refer to it as "forcing open loop" and watching it on a wideband during normal driving that's about what it does. Open loop is anytime the closed loop feedback system isn't being used, ie narrowband oxygen sensors trimming the fuel delivery that's based on maf transfer.

Open loop tables don't automatically go to one value. The table is populated with different values based on pedal position and rpm. I'll post up a screen shot of mine if I can remember how to save and post a screen shot.

I had to look it up and I'm getting away from the topic so I'll stop after this and hope the OP gets a reputable dyno tune that can be tailored to his motor instead of a one size fits all conservative tune.