I just wanted to share this news with Y-Blockers considering the "H" pipe in their exhaust.  The race truck was chassis dyno'ed without the H pipe, with H pipe, and with H pipe and 6" Flowmaster race mufflers.  Also the H pipe did quiet the exhaust a little before mufflers were installed.

Obviously this is not pure scientific research, but it did help me to decide what exhaust configuration to run.  As you can imagine, each and every engine with different cu. in., horsepower and muffler type will give varied results.

Here are my results at the rear wheels with pulls from 3000 to 7000 RPM:

Exhaust configuration     Max Horsepower (RPM)     Max Torque (RPM)

  No H pipe or mufflers               237 (6600)                     211 (4800)

  H pipe with mufflers                 247 (6800)                     216 (5000)

      H pipe only                         250 (6800)                     217 (5000)

For me it was a 5.5% increase in horsepower with the H pipe alone.  Torque is important, but the hp is what helps me push that air at the top end.  An increase in torque should give you a little better performance from stop light to stop light. When I told the dyno tech that the mufflers were by Flowmaster, he said he notices better increases with Dynomax???

When Tim McMaster finishes the new engine, we will dyno again using a new "X" pipe system with and without Dynomax mufflers.  Attached is a picture of the current exhaust system.  Existing crossmembers didn't allow for an H Pipe closer to the header. I've been told closer is better, but I did this on the road between Columbus 08 and Maxton with limited facilities.  The new X pipe system will be much closer to the collectors.  Also Tim has posted a video of the dyno pulls in the "Racing" section under "Flying Yellow Brick at Maxton".

Hope you enjoyed the report.

Charlie Burns Laton, Ca (South of Fresno)



BurnsRacing981@gmail.com

Excellent! How much did the H-pipe help with the average numbers?



Why not go ahead and do the x-pipe and dynomax mufflers for an apples to apples comparison? With the new engine, the numbers will be meaningless in relation to this engine.


Lawrenceville, GA

Charlie,

Thanks for the comment.   You are so correct about the apples to apples comment.  Time and money just will not allow for everything at once.  I really just wanted to know if we were headed in the right direction.  We dyno'd yesterday and today I am removing the old engine and there is no looking back.

I may still do the apples thing.  With the new engine, I will probably chassis dyno with both brands of mufflers along with H pipe vs X pipe system to get even better comparison numbers.

I would love to answer regarding the "average numbers", but I didn't understand the question.  Please help me. 

 

Charlie Burns Laton, Ca (South of Fresno)



BurnsRacing981@gmail.com

It will be cool to do them all just to see what happens.

How did average torque and horsepower compare in relation to the base-line averages?  I guess more easily stated, did it enhance the entire power band or did favor the bottom end or top end?

Lawrenceville, GA

Charlie, I think I would also test the X configuration for the crossover pipe. Supposed to flow even better! Records are gonna fall! Chuck in NH

Y's guys rule!
Looking for McCullouch VS57 brackets and parts. Also looking for 28 Chrysler series 72 parts. And early Hemi parts.

MoonShadow, 292 w/McCulloch, 28 Chrysler Roadster, 354 Hemi)
Manchester, New Hampshire

Charlie,

Interesting question.  The following are the comparisons of torque changes at 3500 and 4000 and max output RPM.

No mufflers, no H pipe:  110 ft lbs @ 3500   145 @ 4000   211@  4800

H pipe with mufflers:     105 ft lbs @ 3500   140 @ 4000   216 @ 5000

H pipe without Mufflers: 110 ft lbs @ 3500   145 @ 4000   217 @ 5000

The H pipe seems to have less torque in the lower rpm range?  Somewhat even at mid-range?  More at the max torque output rpm?  I do not think I would have expected these numbers.  This data certainly does not promote the H pipe for street use.  A street setup engine with these tests would likely show more accurate comparisons.  I trust the DynoJet dyno for accuracy, but as you know there are so many variables to consider to get the data more reliable.  Inputs like temperature and humidity (it was intermittent rain and sunshine), engine temperatures (we didn't log the engine temps for each run), etc, you get the idea.

I don't think I would make a decision on H pipes for street use based on this data, but I do believe an H pipe would help torque in street engines.  Let's see what happens with the X pipe.

Thanks for the comment Chuck.

    

Charlie Burns Laton, Ca (South of Fresno)



BurnsRacing981@gmail.com

Hey Charlie! There is that 200 rpm variation between the first and the second and third pull. How much does that affect to those hp numbers and torque numbers?

I checked our dyno results and at the last pull as for an example the difference between 4200 rpm to 4400 rpm is 8,2 horse powers. 4200 / 304,3 versus 4400 / 312,5 .

Between 4400 to 4600 rpm the difference is even bigger. 312,5 versus 324,0 HP.

Hmmm... interesting.....

 Seppo from Järvenpää, Finland
www.hollowheads.net (just click the hole in the head to proceed)

Hello Seppo,

My spreads are also growing with rpm, but at a much smaller rate than yours.  All my curves are nice, smooth, and fairly even progressions all the way to the max hp and torque readings (probably due to the small engine).  You can almost hear it in the dyno video Tim posted.  Tim also posted the Bonneville record run (camera in the truck) and you can hear the smooth, even climb in rpm while in 3rd and 4th gear (both videos are in the "Racing" section in the Maxton Record Run post).  The non H pipe setup tailed off at a faster rate after both max torque and max hp than did the H pipe setup.

No H pipe & No Mufflers

hp @ 4800 = 196     hp @ 5000 = 199     hp @ 5200 = 203

H Pipe & Mufflers

hp @ 4800 = 200     hp @ 5000 = 205     hp @ 5200 = 210.5

H Pipe Only

hp @ 4800 = 201     hp @ 5000 = 206     hp @ 5200 = 212

Hope you find this interesting.  It is nice to answer technical questions once in a while instead of just reading the posts.

Charlie Burns Laton, Ca (South of Fresno)



BurnsRacing981@gmail.com

Charlie.  Thanks for sharing your data as that is a wealth of information.  You can likely get a better picture of how the curves look by simply graphing all torque data to a single graph and all the horsepower info on another and then observing how the different runs overlap or intertwine with themselves.  I do this frequently with engine dyno data as peak numbers rarely tell the whole story.

Lorena, Texas (South of Waco)

Well that answers a "BIG" question on my new exhaust system. But I'm going to wait and see what the figures are for the "X" configuration compared to it first. Thanks so much for the figures.

                                    Michael

Michael

Sandy Valley, NV