exaust options

[Sonny]

Does anyone have any info they would de willing to share on putting stinger pipes on a "D" mod Merc? I've heard of some guys useing wrap arround pipes like snowmobile pipes, and I've seen some photo's of straight stinger pipes that were adjustable but not set up to slide like a pro exaust. I was just wondering were this technology stood? The megaphones are cool, but I think they've taken me out of the running for neighbor of the year?

[alky6]

Honestly, We've worked out expansion chambers on a Mercury for many years. There is potential for making more peak horsepower with the chambers but the torque curve is so steep (very narrow) that you cannot utilize the power. I suppose if you had a transmission and could keep the rpm at optimal it would work. Unfortunately the cross flow scavenging process does not lend itself to expansion chambers. Stick with the noisy but nastalgic megaphones or purchase a PRO alky engine tp play with expansion chambers. Sorry for the bad news.
-paul

[nightmoves]

Again???

Just say it Sonny.... Y-A-M-A-T-O........... Come on I know you can do it

[Stuboat97]

Exhaust Options

This may be worth following up more seriously. I raced too long ago, but more recently raced OB RC. The pipe man was and still is Jim Irwin. He has worked full scale tuning but is presently into RC outboards. His pipes are the best and the newer QUIET pipes are even better than the noisy ones. I talked to him on the phone about building quiet pipes for 22 ci OB's. Anyone inclined to climb out on the road to the future of performance and doin' it quieter should at least talk to Jim. He's near Indianapolis and very excited about what he does. I ran his mod engines and pipes and think that he could help in the quest for quiet.
Contact Irwin Products by Phone: 765-747-4190
Hope this may help.
stu

[switzerbullet]

Doesn't water injection into the elbows help to quiet down the megaphone exhaust. What about a high pressure mist like an intake water injection system instead of just running water out?

[pro350hydro]

Doesn't water injection into the elbows help to quiet down the megaphone exhaust. What about a high pressure mist like an intake water injection system instead of just running water out?

Water injection can help quiet down an exhaust, and can also help adjust your usable torque curve if injected properly.

Now with that said, think about the above post that says the torque curve is so narrow, that it is virtually unusable..........

[Sonny]

I hope this comes through large enough that it can be read. It is the horn or bell dementions for the alky merc motors and the horsepower spec's in relation to rpm's. I can e mail the full size image to anyone who is interested in having it. But the info suggests that a stinger pipe is a home run. This water injection deal sounds pretty interesting too. Does anyone have any photo's of a working water injection opperation??

[pro350hydro]

I use water injection to drop the torque curve on my 6. There is no noticable change in the sound .... it is still deafeningly loud.

Agreed with megs, no noticable difference

Stop runnin your Mod motors in your neighbor's yard ..... or get more friendly neighbors like mine

Thats right, find a neighbor who will pull a rope from time to time.

[nbass]

Expansion chambers for a Merk 44

We spent a couple of years trying different expansion chamber designs for a 44 merk with very little usable success. At one point we got a very small boost at very high RPM that was way past the peak of the torque curve. (hence not usable) Our test results indicates that the mean effective pressure for the 44 is too low to have an effective exhaust wave. Other limitations include the exhaust port arrangement and the limited transfer ports.

I would be interested if anyone else made expansion chambers work.

Good Luck,
Neil Bass

[pro350hydro]

I remember have a similar discussion last year or so on here about expansion chambers on mercs. From everything I have heard (like Neil Bass said) it has a lot to do with the porting and the deflector pistons. However, a few chimed in and said they had seen a few guys figure it out. Would like to hear more about people success and or problems with pipes on a merc deflector motor.

Seems like someone back east had a c merc that ran pretty well. Can anyone elaborate on this????

Sattler

[Doug4N]

Pipes

Bob Goller set a number of records with an expansion chamber 30 merc. His engines still hold a few. John Mawk (sorry if I spelled your last name wrong) has one that runs well too. I am working on one as well, still don't have all the bugs out, but it goes faster with every change. The design of the pipe is all important. I do not believe that an alky pipe will work, higher power engines need large angle divergent cones. I think a more conservative design is necessary

[jeff55v]

Chambers on a Merc?

I too have read a lot of inquiries on this subject over the past couple years. I've never tried expansion chambers on a merc myself. They don't work well on a deflector piston seems to be a popular reply to the question from other people. Maybe good 'ol low tech megaphones are the best thing for a low tech deflector motor? ( no offense )
I've heard before about some race site sponsors stipulating that there be no open megaphone exhausts at their race. That virtually outlaws a bunch of the fast MOD motors at the race site. And the noise problem has propted some race sites to become strictly S.O. races.
Gee, if only there were a competitive loop charged motor that was legal to race in the D MOD class. Are there any on the drawing board for the MOD commission? If so, maybe then development of a functional set of expansion chambers could be possible. A quieter D Mod class might be more popular with the neighbors and race sponsors alike.

[Dave M]

Whatever

You know, I tried this quiet them down thing not long ago on this site, I thought I was going to be getting mail bombs in the mail from the responses, so I dropped it. Nobody seemed to want to work anything out, and if they knew anything they were not telling anyone. Oh well, best of luck.

As for chambers, you can get them to run on a 44, you just can never get the peak performance. They work, just not as well as megaphones. As someone said, these deflectors have been around a long long long time.

There, my two cents worth, which apparently is worth less than a haf a cent.

[Abbott Racing]

back a number of years ago, Chick Larose, drew up a set of plans for expansion chambers for my e mod (merc) I will make an effort to go through my bookcase and find that set of drawings. If I can find them I will scan them and send them to Dan to post on the site for the members.

[Mike Schmidt]

Pipes....

The 22/44/66 inch Merc's run very well around the race course with open pipes. They can be made to run faster or punch harder with chambers, but not both. Back in the early '80s the guy that designed Goller's C Mod pipes (Larry Honeyman) designed a 25 Mod pipe for the Dewald's. I built them the pipe, elbow and bracket. It was 3 MPH faster than the Bayer open megaphone they were running. If there had been good water at the kilos in Lowell, it would have owned the kilo record. Back around 1986 I built a setup for a "E" Mod Runabout based on the same pipe for George Luce. It went O.K., just not as good as his O'brian open megaphones. When he got out of boat racing Ken Desabrais from up in Mass ended up with the motor. Kenny would run top 3 or so against the open pipe motors of the day. If he got a great start or Fryklund screwed up, he could win. When the race site required closed pipes he would flat kill them. For a fast "play" motor they would work great. For a race site that has noise problems, they will work great.

If someone more computer literate than me wants to post a sketch for me, E-mail me your address and I will mail you a sketch to post.

Michael D-1