Wanted: Filler block for 25 merc

[Art K]

C- Mod

Hey, guys, I think you are mistaken about Steve Wheeler's 400 Mod Hydro. He doesnt run a 25XS ...he has the 22ci. piston port engine adapted to a 25XS midsection. An open Parker pipe wouldn't work on the loop charged 25XS anyway, it would just make a bunch of noise. Now, an expansion chamber might? I'dlike to try that myself. FYI, the 25xs is only legal in the 400MH class when in the Stock configuration and that is with a carb restrictor. Mike Raceboat61-S

Legal C-mod in NBRA I built one it ran really well, just did not have the time for it as we run D & E hyd & run also. Sold it to another guy and he just doesn`t have the bucks to develope it. I am sure if a few more bucks were spent and some time spent testing it could be more than competitive.
Art K

[Zmenard]

does anyone have a 25xs mid and lower for sale? Id like get my hands on one for sure.

[SPW]

25xs

Just as a point of clarification, The 2014 Modified Technical Manual lists the Mercury 25XS as a legal engine, in stock configuration and with a specified restrictor plate, only in the 350ccMOD runabout class. It is not a legal 400ccMod engine.

john sharp

[dwhitford]

Tuned Exhaust

An open Parker pipe wouldn't work on the loop charged 25XS anyway, it would just make a bunch of noise. Now, an expansion chamber might? Mike Raceboat61-S

Probably not entirely true. While I have no experience with a "Parker Pipe", I do know that a properly tuned and shaped megaphone can help increase output in loop-scavenged engines by increasing the breathing capacity, by helping expel exhaust while drawing in fresh combustion charge. Else why would megaphones have worked so well in 1960s-vintage loop-scavenged Koenigs & Quincy Loopers?

The megaphone draws air, one direction only, hence only partly effective in enhancing horsepower. The midsection and tailcone of an expansion chamber, if all dimensions are right, help to further increase horsepower by stuffing back in some of the expelled fresh charge drawn thru by the megaphone, and hence "going to waste". If timing is correct, this waste fresh charge gets stuffed back into the combustion chamber by an expansion chamber just b4 the compression stroke, and hence does not go to waste in producing power.

Exhaust-port timing, and RPM are the key factors in the design of the length of a tuned chamber, why the PROs have resorted to sliding pipes since the late 1960s: lower RPM from the corners means a longer pipe, and so on in the straightaway, toward shorter & shorter as RPMs increase.

At the lower peak RPMs of Mods (compared w/ PRO engines) the chambers need to be longer to be effective. Added length leads to increasing support problems to overcome cracking & breaking. Were I to start a Mod-engine project, I'd seriously consider turning the powerhead around 180º to reduce the supported length of the exhaust. I'd also run some tachometer test laps to discover the RPM range between corners and straights on a typical oval. This would help me design the best sliding range for the system. In general, the longer the slide, the better. And I'd add water injection, a whole 'nuther topic.

And then I'd patent & market the system ... :<)) -- dave

[brill27]

yea mike I think your right,the 25xs is only legal in 350cc mod runabout in stock form with a restrictor plate. a 25xs is not legal in any class with a pipe on it in apba.

[Zmenard]

i found what i needed in the old mans shed that i got the stuff from. I have just been over looking them. I went from needing one to now i have 7 of them!

[ZUL8TR]

25xs

does anyone have a 25xs mid and lower for sale? Id like get my hands on one for sure.

What about a complete 25xs? I have a seller here in the Orlando area who has 2 of them and a 25xs complete gear foot all new rebuilt by the foot-doctor and a 25xs gear foot housing. No mid sections.

[Zmenard]

Can you pm me prices on all of it please

[ZUL8TR]

Prices

Can you pm me prices on all of it please

Can't get you prices but the owner can give them to you. I will PM you his phone # and you can deal direct.