Exhaust Testing – 272 Y-Block


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By Ted - 15 Years Ago

Here are the dyno results on some exhaust testing performed on a +060 over 272 Y that had stock 1956 ECZ-C heads, 1957 ECZ-B 4V intake, an Isky E4 camshaft cut on 112° lobe centers, and a Carter 600 cfm carburetor sitting atop a ½” phenolic four hole spacer.  This test compares engine performance with a set of long tube headers against a set of rams horns exhaust manifolds.  The headers used are the EMC (Engine Masters Challenge) headers which are a 1.75”/1.875” stepped header with mufflers.  The ram horns manifolds were hooked up to ~5’ of 2½” diameter exhaust piping with no mufflers on the ends.  Also had the opportunity to test with and without the air cleaner for both exhaust tests so here are the graphs for each scenario.

 

 

From a scoring standpoint and without the air cleaner on the engine, the EMC headers with mufflers scored 1564.8 points while the rams horns manifolds and open pipes scored 1547.6.  Scoring with the air cleaner in place had the EMC headers at 1536.3 points while the rams horns manifolds scored 1500.5 pts.

By YellowWing - 15 Years Ago
Interesting how removing the air cleaner moved the two setups so much closer in performance. Thanks for all the testing you do Ted. Mike
By Unibodyguy - 15 Years Ago
Ted I actually thought there would of been a whole lot more difference than what there was between the two. I guess the old Ram Horns aren't as bad as I thought they were.
By pcmenten - 15 Years Ago
Ted, Thanks for posting those graphs. Seems like the ram's horns do alright. Do you think the 1.75/1.875" headers are optimal for a 282" y-block?



I notice a very slight inflection at 4700. It's no big thing but it caught my eye. Valve spring harmonics?



And I was a little surprised at the lobe centers. The street power Y-block cams usually get ground on 110 degree lobe centers. I had assumed that was because of the long rods. I'll have to look a little bit at the E-4 cam specs and timing, but that looks like a nice cam.



Would there be a slight mis-match between the ECZ-C head ports and the ECZ-B intake ports? I'll have to go dig those out of my parts stash to give that a look. I had purchased a couple of ECZ-A intakes and old Carter carbs just to try to get a good matching combination with ECZ-C heads for mild 292s.



Edit: no, the inflection isn't valve spring harmonics because removing the air cleaner cause a noticeable change. Must be intake or exhaust effects.



Edit number 2: I'm going to guess that the inflection is intake harmonics because both the rams horns and the headers have it.
By aussiebill - 15 Years Ago
Ted, as allways we are greatfull for your informative testing results, they help form a baseline for specific engine packages. I was impressed how the rams horns went, although helped by no mufflers to help equalise the headers better scavanging etc, but would it be possible to test R/Horns against standard  cast t bird dual headers. i am thinking the R/H,s may have small advantage but might be supprised, thank you. regards bill.Smile
By Y block Billy - 15 Years Ago
Were these original Rams horns or Mummerts?? are Mummerts modified any from originals????  Were these port matched at all or opened up any?? How much wittling if any can be performed on the Rams horns to bring them even closer to the headers???
By Ted - 15 Years Ago
Unibodyguy (10/31/2010)
…. I actually thought there would of been a whole lot more difference than what there was between the two. I guess the old Ram Horns aren't as bad as I thought they were.
I’ll attribute part of the ‘lack of difference’ between the two tests to the stock unported heads being used.  Ported heads are expected to exhibit a larger difference.

aussiebill (10/31/2010)
…. I was impressed how the rams horns went, although helped by no mufflers to help equalise the headers better scavanging etc, but would it be possible to test R/Horns against standard  cast t bird dual headers.  I am thinking the R/H,s may have small advantage but might be supprised.
Stock exhaust manifolds, rams horns manifolds, a set of Fentons, and a variety of headers are still being planned for a very in depth exhaust test on the 312 dyno mule in the near future.  At this point, I’m still gathering up all the parts and pieces for that particular test using the time proven +060 over 312 dyno mule with the Mummert 4V intake and a Holley carb.  Also working on getting mufflers on hand that will allow many of the exhaust combinations to be tested with and without mufflers.  That 312 engine will continue to use the same 238° @ 0.050” Crower cam that’s been used for past testing of heads, intakes, and carbs along with the Harland Sharp 1.6:1 roller rockers.  Changes to the engine for the exhaust testing will include an Innovators West harmonic damper and a set of nicely ported ‘G’ heads that have also been milled to raise the compression ratio over what it is with stock heads.  Only reason for the Innovators West damper is that the damper ring on the stock harmonic damper finally gave up and there was a spare IW damper sitting here.  The ECZ-G heads for the test will be a pair that have been conventionally ported with the exhaust ports being shaped such that most exhaust systems being used will be compatible without a drastic port mismatch.

I’ll add that ported heads are a prerequisite in this type of test in that power output changes due to exhaust system variables will be more defined if the heads are not the bottleneck.  Simply stated, ported heads are much more responsive to exhaust system changes or upgrades.

Y block Billy (10/31/2010)
Were these original Rams horns or Mummerts??  Were these port matched at all or opened up any??
These were stock and original rams horns manifolds.  Ports in the stock rams horns manifolds still exceeded the stock exhaust port sizing on the heads.
By mctim64 - 15 Years Ago
Thanks for the testing Ted!  Can't wait to see what the "Mule" does with all the other headers.  Sandersons especially. Wink
By grovedawg - 15 Years Ago
Ted,



Thank you so much for putting time into these posts to help us understand what to expect with the different exhausts. Ryan