CMI Sporttubes vs. Typhoon header for 496 HO
11-12-2011, 10:07 AM
#1
CMI Sporttubes vs. Typhoon header for 496 HO
I suppose they are close to equal re. performance, but how about quality over time? I´m thinking about risk for cracks and leaks here.
Also, have anyone experienced reversion or failure caused by lean running using these types of headers on a otherwise untouched 496 motor?
Also, have anyone experienced reversion or failure caused by lean running using these types of headers on a otherwise untouched 496 motor?
11-12-2011, 11:26 AM
#3
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Scandinavian:
I suppose you are going to be boating in salt water most of the time. It will be important to stay with an all stainless header. We have tested stock 496's with the CMI -496 e-top system and we saw about +22HP over the stock Mercury exhaust manifolds with the turbulator plate removed.
Raylar has not yet tested the newer Hardin Typhoon header system. These two are both what I call short primary tube headers and both have a similar 4 tube tube length and collector sizes so I would suspect the power increase to be very ,very similar with either set. As for durability I have not heard of cracking or problems with either of these particular model 496 header kits and I know the both have been in the market place now about two years. I know the CMI 496 E-top header kit is priced about 10% less than the Hardin Typhoon but that is standard pricing and I don't know if either manufacturer will meet each others pricing, that's for you to negotiate.
As for header maintenance it is very obvious that flushing after every outing and use is critical especially with fairly long intervals between use and completely draining all the raw water from the header and its plumbing is mandatory for winterization in cold climates where freezing occurs. I would also say its not difficult to pressure test these header right on the engine with compressed air. This can be done fairly easily once every one or two years depending on what your usage is.Plug the raw water entrance fitting and put about 40-60 psi of air into the other outlet at the collector and listen carefully for air leakage and use a guage to see any pressure drop after the system is pressurized.
As for the possibility of leaning the air fuel ratios with either set I would suggest if you have a Merc 496 Mag Or HO engine you can purchase a Raylar adjustable fuel pressure regulator kit and it will allow you to turn the fuel pressure up to offset a slight fuel lean condition that could be present at higher rpms under full loads. Our dyno testing showed that this type of shorter tube header tended to lean the top end air fuel ratios slightly more so on the Mag engine than the HO engine and this condition will vary depending on the model year and its specific programming in the ECM.
Hope this information helps with your selection process.
Best Regards,
Ray @ Raylar
I suppose you are going to be boating in salt water most of the time. It will be important to stay with an all stainless header. We have tested stock 496's with the CMI -496 e-top system and we saw about +22HP over the stock Mercury exhaust manifolds with the turbulator plate removed.
Raylar has not yet tested the newer Hardin Typhoon header system. These two are both what I call short primary tube headers and both have a similar 4 tube tube length and collector sizes so I would suspect the power increase to be very ,very similar with either set. As for durability I have not heard of cracking or problems with either of these particular model 496 header kits and I know the both have been in the market place now about two years. I know the CMI 496 E-top header kit is priced about 10% less than the Hardin Typhoon but that is standard pricing and I don't know if either manufacturer will meet each others pricing, that's for you to negotiate.
As for header maintenance it is very obvious that flushing after every outing and use is critical especially with fairly long intervals between use and completely draining all the raw water from the header and its plumbing is mandatory for winterization in cold climates where freezing occurs. I would also say its not difficult to pressure test these header right on the engine with compressed air. This can be done fairly easily once every one or two years depending on what your usage is.Plug the raw water entrance fitting and put about 40-60 psi of air into the other outlet at the collector and listen carefully for air leakage and use a guage to see any pressure drop after the system is pressurized.
As for the possibility of leaning the air fuel ratios with either set I would suggest if you have a Merc 496 Mag Or HO engine you can purchase a Raylar adjustable fuel pressure regulator kit and it will allow you to turn the fuel pressure up to offset a slight fuel lean condition that could be present at higher rpms under full loads. Our dyno testing showed that this type of shorter tube header tended to lean the top end air fuel ratios slightly more so on the Mag engine than the HO engine and this condition will vary depending on the model year and its specific programming in the ECM.
Hope this information helps with your selection process.
Best Regards,
Ray @ Raylar
Last edited by Raylar; 11-12-2011 at 11:29 AM.
11-17-2011, 12:59 PM
#4
Thanks a lot Ray for taking time and posting such a long and informative answer! Seems like reversion is not a big issue since You don´t mention it. Re. fuel pressure I think I can monitor it through my Livorsi Smarcraft gauge, if not I will contact You. Thanks again!
