Flint

So...uh...what's the, you know, procedure for gutting a cat? I only ask because I recently lost a smog pump, and was kind of noticing that it ran better, heheh.

Ketchmi

Uh, I have two authentic Ott's at the shop, one has never been installed.........

Gutting cats is a pain in the a**! A long prybar with a flat end, driven repeatedly through the ceramic substrate while twisting to remove the wire structure at the same time. Not fun and not something you want to breath in too much.........

Tom Cloutier

I have been making X-pipes almost steadily for the last 2 months. The new X is very much like Louie's (the critical inlet and outlet angles and the width of the venturi throat remain the same), but I have modified his layout such that cats similar in size to the Random Tech units can be easily added and even replaced by interchangable straight pipes, such as on George Suennen's car, if desired. Louie and his wife spent a few days with us in Berkeley recently and Louie was VERY impressed with the new X.

All my welds are done with a TIG welder. It's much slower, but looks much better than MIG welding. Where necessary, the joints are blended inside the pipes to facilitate smoother gas flow. The 3/8" thick steel flanges are welded to the down tubes from the inside for a much better appearance than those welded on the outside. Then the pipes are sprayed with 3 coats of high temp ceramic paint.

I have just ordered a new ceramic coating good for 2000-deg F. The ceramic coating insulates the pipes, reduces the amount of heat transferred to surrounding parts, protects the pipes against corrosive exhaust gases, changes the pipe texture to increase flow rate, and most importantly, keeps the exhaust gases hotter. The higher temperature increases the kinetic energy of the gases which means they flow faster. The faster the gases are removed from the exhaust system, the less back pressure the next cycle of gases see when the exh valves open. This means increased performance. I expect to be able to offer this coating for about $50 per X-pipe.

Some of you asked about gutting cats. In general, this is not likely to improve performance very much (if at all) unless your cats were severely clogged. The problem is that the exh gases are flowing rapidly down the 2.5" diameter pipe (or whatever you happen to have) and then suddenly enter the huge volume of the empty cat. The gases expand to fill this volume and lose speed as a result. This could even result in a power loss! I don't have any dyno data to show this, but that's the theory. A way to overcome this problem is to weld a pipe into your newly gutted cats. Don't be deceived by louder exhaust systems--the extra noise does not necessarily mean more performance even though it seems so.

I don't know what to think about the cat situation. I showed the Random Tech cats for George S's car to a friend who runs a muffler shop and he said something like, "Oh yeah those are just pre-cats. They'll rot out after about a year." I've been hearing similar stories about the relatively short life expectancies of these cats. If in fact the cheaper Magnaflow, Carsound, etc cats have similar flow rates to the big buck cats, why not go with the cheaper ones? Any cat with a 2.5" inlet and outlet and similar length to the Random Tech cats (7" - 8") and a diameter no greater than 4" will work with my current X design.

Someone mentioned the power gain after putting the cats on George S's supercharged car (I think). We can't draw that conclusion. When you reduce the flow restrictions, as we did by installing the X, the supercharger can attain higher boost pressures because there are fewer pumping losses with the free flowing exh system. So we saw increased power, but can't really say how much was attributable to the X and how much to the increased boost pressure. When we added the cats we saw a further increase and I think higher boost pressure too, but this was definitely not because the flow rate was greater with the cats than without. The most likely explanation (from Tim Murphy) is that the drive belt was probably gripping better.

So what does one of my X-pipes cost? $350 including shipping within the continental USA. $450 for 304 stainless steel. About $50 for a black ceramic coating. Included are an oxygen sensor bung and 2 heavy duty band clamps to attach the X to the stock pipes. Installation is pretty straight forward and can be done on jack stands in your driveway with only a few hand tools.

I hope this information is useful.

Tom Cloutier
the Power Broker

Lagavulin

This statement is incorrect. Reducing flow restrictions will result in lower registered boost pressure since boost is merely a measure of ....flow restriction.

James-man

Tom,

Have you put this on your website yet?

Thanks!

heinrich

Yep you're right. Good catch but I think at least his intent is good in that free flow == .

Tom: I want a 350-dollar unit and would order one today. However ... I want to see dyno results as compared to a true Ott X ......
Heinrich

Warren928

Jim,
49 hp from an X-pipe and MSDS headers is a healthy increase!

Blau, you may have posted this or someone else has, but how does the X-pipe with cats increase / decrease HP?

blau928

Warren,

If the Cat poses no restriction, then it will not affect the power output.. In supercharged systems, in several cases cars have made more power with the Random/Race cats on.. I suspect it has to do with the scavenging effects of the entire system, and the pressure and gas flow associated with it.

Exactly why, I am not sure, as I have not studied thermodynamics and airflow computation or fluid dynamics etc..

However, it has been observed on several different models of cars... Ford Cobras to 928's (George's)

I will test mine when I have finished installing my SC system.. I can let you know then if it turns out to be the case as well..

Regards,

blau928

Warren,

There are two types of Random Cats.. Ceramic, and Metallic.. The metallic ones flow a bit more ari I believe....

Tom Cloutier

Lagavulin,
Thanks for catching that. I fell prey to the common lore and you've given me the opportunity to think this through. It seems that perhaps exhaust system efficiency has little effect on boost pressure since we are primarily pumping into a closed cylinder rather than directly into the exh pipe. Where the improved pipe flow comes into play is through better cylinder scavenging and therefore a more concentrated incoming charge.

I think the increased boost on George's car must have been a result of improved belt grip. If no changes have been made to a system and one sees higher boost pressure, then there's probably a potato in the exh pipe!

What are your thoughts about this?

Cheers,

Tom Cloutier

Benton

Tom,
Are the TIG welds on the SS back purged?

heinrich

Tom, again:

POTENTIAL CUSTOMER ASKING AGAIN:

Can you post dyno numbers on your X vs Louie's?

Vlocity

I have a set of MSDS Headers on order. Does anyone have a ready to go X- pipe that will join up to the headers?

Regards,

Ken

Ketchmi

Not us, we don't plan on doing custom X-overs, just the plain old generic kind that bolt up to the factory system, in stainless, or mild steel, with cats, or without cats, with as many O2 bungs as you specify.

heinrich

Dave I assume your pricing will be favourable?