Thanks for doing the before/after dynos CJ. Most did dynos after all mods and noted increased throttle response/etc.

I know of only one before/after dyno on the 200 cell CATs was told they decreased HP slightly.

I have brought this up numerous times (I would buy if I saw results), but it keeps falling on deaf ears.

 

Was that anything to do with Star Motorcars?

 

Reducing HP is kind of hard to believe, I'd have to shift more towards increased horsepower and maybe if any slightly decreased torque becasue of the reduced back-pressure..never heard of any high-flow catalyst reducing HP from a Before and After dyno on any brand

 

Yes, one of the Star locations.

 

OK boys, heres an update:

I received my cats last week, they were in a pretty battered box. I haven't had a chance to open them, and inspect them, but I will on Friday. If all is well, I will be installing the cats sometime late next week or early the following week after that.

Maybe I might be able to get in on Monday, we'll see.

As far as the before and after dynos....... wait for it..... wait for it..... I will be doing the before and after dyno by the shop that installs my Cats. Lets all hope for a nice bump in power, I will post my results regardless of what the outcome.

 

Irish-

I am sure that there are quality levels, even in cats. Is there a case to be made that designs/construction quality might affect the hp/torque scale? I have to assume that the quality of construction would dictate differences, in the same vein that any consumer product would, and might account for +/- hp and torque variances; one company might show an increase in both, and another would show hp but lower torque.

 

Well anything in this world is possible..the engine is a giant air pump, the faster th air can come in and the faster it can come out is the change in horsepower, the less destorated entry of air and the less destorted exit of air is the change or torque...so if you put a 200 cell cat you increasing the flow and destorting the air flow on exit..aka noise destortion..by doing this in this situation you will most prob see a nice increase in horsepower and either same or close to previous torque or at times a decrease..

Really your on the right track and this takes a lot of variables to count..like what type of headers are they and will they perform better with a 200 cell cat..V8V's have a a mid length header..there longer than the normal shorty and shorter than the usual long length..I believe the real difference between these manufactures of these cats will be the size of piping rather than the cat cell(a high flowing cat cell amount is the same on all, that's if the manufacture whats to make a cat for OBDII vehicles)..so my conclusion(just looking at number on paper and not stuff like contrsuction..so contruction would be the same on figures), would be larger piping will net more HP and no real change in TQ, the small piping(same as OEM on entry and exit) will net more torque and some rise in HP..

If this vehicle was forced induction..theory would be slightly different..

 

Once you switch over from OEM style cats to the metal matrix high flow units, it really comes down to the quality and also quantity of the catalytic materials themselves - the coating that is on the cellular matrices. If you are using a high quality, high gsm loading, you can then reduce the cell count, resulting in better airflow (and less head buildup.) For example, on the V8, the stock cats are actually a 600 cell primary and 400 cell secondary with an O2 sandwiched in between. If you use a high quality/quantity catalyst material you can go as low as a 200 cell count matrix and still run within the system's 'normal' parameters.

 

I should have been more precise. but that was the track that I was on: What I was looking for was a relationship between the quality of the cats themselves, and the results that various quality levels bring.

 

That's the right track - basically, the higher the quality, the lower cell count you can get away with without triggering CEL's. (that's a little simplified but basically right)

 

CJ-
Any updates on the install and dynos?

 

Its a hassle for me run up the tuning shop on a weekday, so its taken me a while to get it scheduled.

I really want to get it done ASAP, I hope I'll have it done the week after next.

 

$75 before $75 after

 

I have Larini cats and a Milltek rear box. Love the sound despite some droning on the highway. Crackle- pops and 30 lbs of weight savings.

 

Today's the day. Getting the cats installed and doing before and after dynos.

****UPDATE*****
Just did 'before' dynos and max power was 338hp at the wheels and 273lb ft. torques. Done on a dynojet, and video recorded. Will scan sheets for people tonight.

Its currently +31 degrees, 82% humidity, 30.58in pressure.