Bruce Nunnally Posted October 31, 2015 Report Share Posted October 31, 2015 Honing out the Y Pipe, this is a Cadillac Y Pipe, the years range on all models of the Deville from 93 thru 2010, the Eldorado 93 thru 2002, the Seville 93 thru 2004. Bruce 2023 Cadillac CT4-V Blackwing Follow me on: Twitter Instagram Youtube Link to comment Share on other sites More sharing options...
Cadillac Jim Posted October 31, 2015 Report Share Posted October 31, 2015 I looked for headers for my 1997 ETC for years and never found anything other than mention of something that went under the oil pan, which is unacceptable for the street. This is the next best thing. If there are dnyo numbers/curves for a car with and without this treatment, no other changes, that would sell it pretty well, I would think. -- Click Here for CaddyInfo page on "How To" Read Your OBD Codes-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data -- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC Yes, I was Jims_97_ETC before I changed cars. Link to comment Share on other sites More sharing options...
KHE Posted October 31, 2015 Report Share Posted October 31, 2015 If this made a significant difference, I would think GM would have specified the pipe be machined at the original supplier. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
Bruce Nunnally Posted October 31, 2015 Author Report Share Posted October 31, 2015 If they both dumped into a larger collector air velocity would be an issue, but since they merge to a single size pipe the mod seems intuitively to improve flow. it would be seem best to replace with a true Y pipe further down instead of modifying each one by hand, but not sure the market is there. A chain style pipe cutter might work well here but no clearance. I agree it would be nice to flowtest but that needs a test bench and people would still ask for road and dyno tests and buyer reviews. Bruce 2023 Cadillac CT4-V Blackwing Follow me on: Twitter Instagram Youtube Link to comment Share on other sites More sharing options...
Timothy Carroll Posted October 31, 2015 Report Share Posted October 31, 2015 Hey guys! I know this does make the same sense to some as it does to us as engineers, but anything inside the pipe will have some kind of back pressure, in this particular case an 1-1/4" of pipe was a bit extreme! We see them much less and rarely more then that but in any case it was a serious restriction. If you have seen our header builds we have built with dual flex and a two point collector for as much flow as possible then you understand we know the flows, you can view one of these on our site. The two point collector is expensive to say the least and is done in your car. The question is; how much difference between the two point collector and is the honing of the original and believe it or not? it is less difference then the honing versus leaving this blockage inside. I think we will do a visual smoke video of how this restricts and take the doubt out of it, but I am a busy man so it won't be tomorrow, LOL but as with all things I will get to it. I explain it this way; you have a single pipe going to your split in the rear to two mufflers, both mufflers allow exhaust to escape? Now, they are coming out of one pipe slightly larger then the two splitting off, but the two splitting off make up for more volume of flow! If you were to seal off one side? You still have an open port, correct? Because you are now using a smaller volume of escape then the pipe coming from the front, it is bottle necking it at this point, yes it will feel much more powerful of pressure coming from the one side but much less then the two were allowing together is actually escaping ! So you ask yourself, where is the extra volume that is not being allowed to flow out of the one side? This is called back pressure, like it or not your flow is slowed! Not much, but a little. This is the same issue with this blockage, for the average Joe it may not be much, but for the guy looking for max capability, this is substantial. Link to comment Share on other sites More sharing options...
Timothy Carroll Posted October 31, 2015 Report Share Posted October 31, 2015 To KHE, Why GM did a lot of things is questionable? To say the least! From the day they failed the first Northstar to the day they discontinued it, never once did GM Engineers solve the Head Gasket issue, but between Jake and myself, well, we solved it overnight, oh and most of that credit can go to Alan Johnson after all he was doing it before we were. We call factory hold back a drive 55 era. Link to comment Share on other sites More sharing options...
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