Might that sort of sizing difference benefit the street headers?


Lawrenceville, GA

Charlie.  You’re on the right track with that train of thought.  What I’m finding is that the collector size itself as a general rule likes to merge down significantly and then expand back out to a larger size.  For the dyno mule, the collector being necked down to 2.5” or thereabouts while the extension behind is larger.  That larger section acts as an expansion chamber and helps to dampen some of the reverse pulsing that is trying to take place.  Then using larger pipes behind this must be used to insure that the flow to the end of the exhaust is not being inhibited.  This has been supported by the fact that the better test values always come about with the larger sized pipes being used.

 

There are some real opportunities to be had in using high flow mufflers also.  Many of the chambered mufflers that have been used thus far in the testing have been a detriment to overall performance.  At this point, I suspect that the EMC headers could stand some additional downsizing on the merge collector.  Right now it’s at 3” and at the time of testing on the EMC Y engine, that was the smallest merge collector on hand.  In fact, Geoff Mummert supplied the one that’s in the headers now.  I’ll also add that Jerry Christenson and Royce Brechler provided the original EMC headers which have only since been modified in the collector area.

Lorena, Texas (South of Waco)

Ted, do you have to run a chamber Muffler for the engine challenge? With our race engines we have found that a straight through glass pack style runs just as well as no muffler. shoenfield style hurts a little, and chamber style losing up to 80hp.

Jepito. The only rules limitations for the EMC competition regarding mufflers dealt mainly with outlet sizes and overall dimensions. Actual muffler design could be varied as long as the muffler fit within the size dimensions specified in the rules. The mufflers used for the Y in the EMC competition were the Magnaflow straight through design and those particular mufflers with the other header modifications actually complimented the overall scoring for that particular combination. Although the peak horsepower does go up when the mufflers are removed from the headers, the scoring falls off significantly and the EMC competition is all about scoring, not peak numbers.
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Here’s the link to the previous page showing both the horsepower and torque graphs using the EMC headers with and without the Magnaflow mufflers as compared to the Sanderson headers on the 312 dyno mule. The EMC headers with mufflers have a very favorable ‘very flat’ torque curve.

http://forums.y-blocksforever.com/FindPost57447.aspx

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And here’s the link to the thread that gives a better description of the EMC headers as well as a picture of both the EMC headers and Magnaflow mufflers.

http://forums.y-blocksforever.com/Topic51508-3-2.aspx

Lorena, Texas (South of Waco)

Ted, did you post the lower RPM results for these test? I have a 64 F100 and would like to update the exhaust to maximize lower torque.

See if this set of graphs helps. This info actually indicates that it may be better in this particular instance to not use the crossover pipes in the exhaust on an engine that's simply running at the lower rpm band most of the time. My own experience with crossover pipes on daily drivers is that they do mellow out the exhaust notes on a V8 and stop some of the ‘popping’ noises that can occur out of the end of the pipes while cruising.

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Lorena, Texas (South of Waco)

Thank you for the information and all of your contributions to the Y Block commiunity. I look forward to reading your post whenever I log on. My quest is for power in the 1000-3000 range and it looks like the cross over is shifting power ever so slightly upward. A good mellow sound is also good so I will start with the ram horns go from there. I am considering a "h" configuration for the exhaust with the tail pipe exiting behind the passenger rear tire. Do you have any recomendations on pipe sizing for an engine that will never turn more than 3500?

True.
I like more my non-crossover Y-Block sounds in Fairlane than the sounds of injection era Mustang with crossover. You can hear Y-BLock beat in stereo while standing behind the car.


Hyvinkää, FI

While a normal thought process might indicate that the smaller sized pipes would enhance lowend torque production, dyno testing that was performed on a Y engine with the different sized pipes indicates otherwise. Here are the graphs showing HP & TQ attributes with the different sized tail pipes installed on the 322” dyno mule.

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Lorena, Texas (South of Waco)

damn! what she said, bigger is better!!! say ted, did you ever test those big tube headers on anything?

 lincoln/merc. y-blocks &mel's                                                               bucyrus, ohio.