Making your own hyperflows...

So I had a '89 Mondial t, with no cats/O2 (lambda). It stunk to high hell and ran excessively rich at 383 ohms on the MAF. I added the O2 (lambda) which eened out a rough running and found the mixture point to be closer to 470/530 ohm for L/R banks. I have posted to how I did this, the pins and wiring.

With O2's I wanted to go further and eliminate the stench of the exhaust (the O2 changed it from tear inducing and dizzying to a mere smell typical of older cars). So I bought two universal catalysts from Magnaflow (part number 59954) with 100 CEL metallic cores. These have a matching 2" diameter, are spun casings and fantastic value at USD150-200 depending from the source and country (US eBay). My car came with straight pipes. I removed them and the exhaust box, and I then had them TIG welded for GBP 160 at the fantastc www.rodznsodz.com crew in west London (UK) about 2in. aft of the O2 boss, and reinstalled everything. We made an aluminium heatshield to protect the starter engine from some lightweight sheet.

Here's the result. On a dyno the before and after numbers were identical 296 RWHP before and 297 after (within a measuring tolerance of +- 3%). As to the effect, when first started the smell is the same, but within 5 minutes there is NO smell, in fact the exhaust is like a damp blow-drier blowing in my face.

I drove the car to Paris over the weekend (670 miles btw), and pulled over after a 10 minute WOT drive, cats were slightly purple (like a motorcycle exhaust) but no glowing or anything else.

Total cost was $375 for te cats, and time and materials. I enclosed some pictures, and found out that hyperflow, stebro and many others use the same Magnaflow cores. Difference is in the chroming/polishing, which quite frankly won't last the first rainy drive. So I got 100% hyperflow performance but for 1/3 of the price and 1/2 a morning of metalworking...

Enclosed are the pictures.

Marco
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How do we do the induction - I have a spare Gearbox to be tested on... ;-)

Marco

 

It seems I bought the wrong cat from my expectation, and a few people in the forum misunderstand the CEL ratings. By explaining this I show how I dummied, however it is for the greater good.

The CEL number denotes the number of cells (holes) the cat has per square inch. The definition of a hole, is that it must be surrounded by something (otherwise it would be a space), this something is the catalytic converter matrix. If you have more CELs, then you have more holes, then you have more matrix. Now you collapse all the cels, and that matrix, will turn into a solid mass. The more CELs, the more matrix mass. Clearly the more CELs the more efficient a given core is for a constant length as there is more surface for the oxidation to take place on.

So in order to meet specific emissions, you will find that the lower CEL cats have longer cores, and the higher CEL cats, shorter cores (or multiple cores). Usually, cats have wider cores than the inlet pipes, so that the overall area of all the holes matches that of the inlet and outlet. You will find that most catalytic converters (modern ones) tend to flow very close to straight pipes. The problem comes when you have high CEL cats who then become more prone to clogging as the holes are smaller.

I may have 300 CELs, while I believed they were 100 CELs, so that is a ding on me. But 100 CEL is less restrictive than 300 CEL for a given diameter. Now to meet EPA and other regulation, you will find that 100 CELs will be a number of times longer cores than the 300 CELs. Fluid dynamics tell us that turbulence increases along a steady diameter, so I believe that the truth of CATS is somewhat balanced.

If I inadvertently (giving me credit so I don't have to say stupidly) put in 300 CEL, I can then tell you they had NO effect on the power output on the engine. I dynoed the car after fitting them and the O2 system, and I had +- 3% variation along the curve, which is within the calibration tolerance of the system.

I don't need the extra 7 hp at all costs, this is my family daily runner, I now have a smell free car, running at optimal emissions and fuel consumption, the engine hums, and I did it all for under $1000 and 3 days worth of work. Considering that is all cheaper than a single hyperflow, well I think I'm ahead.

Consider that the hyperflows probably have 1-3 % better flow than my set-up, spend your money, I'll save mine ;-)

Marco

the flow is only restricted if the core part of the catalyst is not wide enough

the holes are surrounded by

 

So I did that too, just was too lazy to post it... Took me 90 minutes, made NO difference, however finally removed a rattle...

Had to cut the outer lining, remove the glass packing, open up the inner muffler can, remove a rattling baffle, then re-weld the whole thing. Could not TIG it as the muffler surface was too rough, so I user a grinder to smooth it out from Frankenstein to cosmetic surgery scarring, and painted the whole thing in high-heat silver. While I was there, I cleaned up the pumpkin and did some other basic stuff...

PS. I called my Magnaflow importer, he confirmed that as far as he knows the 59954 cats I bought were 100 CEL metallic cores, that is what it says on his system. Either way be they 100 or 300 it appears that the only difference was in smell, the performance is identical to the straight pipes I used to have and cut to weld the cats onto...

More pics...

Marco
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On the last picture you can see the aluminium heat shield I made to protect the starter motor from the heat radiation from the catalytic converter...

I'm sure that those cats will melt then evaporate small amounts of oils and bearing greases, which over time lead to dry bearing rollers and seals and their failure...

Marco

 

First of all it was a foray into the Motronic 2.5 system, then it became an attempt to understand the dynamics of emission controls, then an exercise at learning about welding, then one of just making the Ferrari experience a pleasurable for me, my family and neighbors (the noise).

Fundamentally it also was an exercise in giving back to the f-chat community, for those who find stock cats too expensive to replace, for those who want to add a closed loop system to their early (<91 motronic 2.5) euro cars, which may be running too rich or too lean when in open loop, and for the general knowledge, which I dare say was a little thin... and for those who wanted hyper-flows but at 1/5 of the price!

I wanted the whole thing to remain as stock as possible, this is a family runaround for me used 7 days a week (9000 miles in the last 10 months). Thanks for everyone's speculation.

I posted info on how to cross wire your MAF's in the event of one failing. Yesterday, the remaining one failed (in heavy rain), over-reading the air mass, resulting in an over rich mixture. The cats were glowing BRIGHT (not dull) red, the exhaust tone was deeper, there was black smoke pouring out and a very irregular heartbeat. In fact the car only worked fine at WOT (thus on tables).

I bought a BRAND NEW Bosch MAF with part number 0280 212 018 for GBP 190 from a Bosch dealer who told me he had it on a shelf for over 15 years and gave it to me for 1/2 price. I'm back to a shared single MAF, but everything is now perfect again, with a brisker acceleration I may add...

I have to say though, that while terrifying, the catalysts did NOT melt, warp or otherwise. They stood up to the abuse, and when cooled off worked flawlessly again. I took them off, to see if the baffles were warped, no way, not even clogged.

Good on the magnaflows...

Marco

 

My homemade thermocouple sensor relays worked perfectly, I got two warning slow down 1-4 and 5-8 signals. in the M 2.5 there is no ECU shutdown as the 2.7, only the light on the dashboard... Made them with a maplin circuit (same as radioshack in the US) and a pair of 1000 deg. C rated thermocouple probes, total cost GBP 60 and 2 hours of soldering, drilling and wiring...

M