fuelman8

What mods are done to the 3.8 HP zenoah to take it to 5 HP?

I'd like to see if it's something I can do or just buy it with the mods done.

pyro1

Porting & timin, zero drag seals can add some rpms. A good tuned pipe.
I'm sure some engin builders can give you more details about this subject.

Believe It

going to a thinner base gasket (or using no gasket at all) to tighten up the squish (more compression), raising the roof of the exhaust port and lowering the floor of the intake port.. matched with a tuned pipe is supose to make 5-5.5hp without ever touching the transfer ports.

radioactiver/c

Hard to buy a 5 hp (so called mid mod these days) most engine builders do full mod for about $600 , this yeilds 5.8-6.2 hp. Beware of outrageous claims of hp levels of more than that.The factory cylinder casting does not have enough material around transfer ports to suport that power level.

to be breif and keeping this complex topic simple
Set your squish to .018"
stay on the conservitive side with intake and exhaust timing, shoot for 146-148 on intake and 176-178 on exhaust
widening ports without increasing timing will increase power also but don't go too far,stay under 15/16 max width
combined widening and increasing timing will make morepower and increase rpm
swap stock carb to WT257

BB Modss

The zen 7 from the UK makes a true SAE corrected 7hp...

fuelman8

Thanks for the info guys

martno1fan

NOW YOU GONE AND DONE IT LOL

ken0276

My Feedback: (2)

The pond seemed a bit small for that engine, there is big one located at N15 and 169, 4 times bigger but havn't run there yet.

martno1fan

Ken can you elaborate mate ,are you saying you have the zen 7 or are you on the wrong thread just kidding .

ken0276

My Feedback: (2)

martno1fan, I have 4 mod 260s, Zen7 is best for the speed within those 260s, by the way, Thanks for the replying for its specs.

radioactiver/c

that engine was dynoed by an independent and it was no where near 7 hp

The world record is held by Quick Draw, the nearest zen record is 10 mph slower. You won't convince anyone that the zen makes more power than the QD.There is only so much you can get from a zen and the top engine guys in the US are getting all that can be wrung out of a zen.

BB Modss

Who did the dyno test and what dyno? Ken has the zen 7 and he out pulls my QD25ht!

Also,since you seam to be a bit snippy, no one was saying zens make more power the QD's.

martno1fan

Mate i got shot down plenty of times for even telling guys the zen from dave was rated at 7hp let alone anything else.All i can say is this that that motor has beaten qd 25 and 35 motors in races and by more than two laps and thats FACT.Of course boats and setups come into the equasions too but im glad to see someone over there supporting the 7 hp claims.My mate has just aquired one and will be testing it for himself pretty soon.As far as i know no one has run a zen 7 in a speed record attempt? .Dave uses his for racing and seems to do ok for a begginer sorry Dave couldnt resist .Ken have you had it dyno'd or have you had it gps'd at all? my mate is planning on using it in a cat from Dave and apparently the ptototype did 69+ mph so it should be fun [X(].

Believe It

i can make a bone stock 302 sbf make over 700 SAE corrected HP on a engine dyno.... the fact is there was a zen7 dyno'd here in the states, it didnt make anywhere near 7hp, nor did it run like it made anywhere near 7hp... just stating FACTS.

BB Modss

Show us the dyno data,and dyno specs, I do not own this motor, but my buddy Ken does and he walks away from my cat with his zen7! This need not be a pissing match, The motor is strong, why does every one say "no where close" when they wont say what the motor DID make, what was the relative humidity and pressure? altitude? Have Dave post the dyno charts he made, have the other dyno guy post his, what type of dyno? fluid brake or inertia? what rpm's were achieved? What is the port timing on his motor?


Im all for a stronger zen, but see me eye to eye on this guys, Provide some hard data for us to go on, if his motor isn't making 7hp then what is it making, what pipes were tested?

radioactiver/c

7hp claims are about a full hp than the best US builders and more than QD.
You slam the US builder who hold the world record and QD in one shot, nice shooting Tex.
The dyno run was made back to back with another 260 from top engine builder, both made just about 5.8 hp
Back to back test take the question of dyno type out of the equasion.

The US engine builders hold the record, and make about 6 hp, how is it that only one guy can make nearly a one hp more and no one else seems to be able to do it?
If the top engine builders in the US can't get 7, then it can't be done. Go to IMPBA and NAMBA and look at the record book for yourself.

BB Modss

I know the records, Im not shooting any American builders down with any of my statements, I simply want to know the facts. When was a zen7 ever given the chance to run a speed record?

Believe It

I talked to the person who dyno'd it myself, and am also friends with the OWNER of the motor. There is no need to give you numbers, because like i said... i can put a stock 302 (that only makes 225hp) and have the dyno read a SAE corrected 700hp. Dyno's also do not give a 100% true and accurate number. They are for testing to see if you make accomplishments or not.

Forget the DYNO numbers, the boat ON THE WATER could not produce numbers that his regular US built mod Zen's could turn out... but is supose to have 1hp more (and more torque...)

M&D's real zenoahs dont make "7hp", and didnt see "7hp" with a zen based motor until the custom CAST jug. Butch, Carlo, Al, Ron Buck, etc. dont have a 7hp zen, but Dave does. Thats cool... he must know some serious tricks in these old school tech motors that nobody else does to be making almost a full 1hp more then the top builders here in the US.

If Ken's Zen7 outruns your QD...thats cool.. maybe its in the prop? setup? hull alone? Are you comparing IDENTICAL boats with IDENTICAL setups with IDENTICAL props with just different motors?

Believe It

making more hp and torque, Dave should come reset all IMPBA LS27 records then.

martno1fan

This is just gonna get uggly again so i just wanna say lighten up guys and Happy Christmas

BB Modss

Im all for progress, But lets try to give the motor some credit, it has taken a handful of records over in the UK, Lets all buy one for xmas and give them a shot next spring, I had made plans to buy a set of them, 1 for me, 1 for Bob so we could do some in water test.

On a side note,
That M&D jug is sexy looking....

martno1fan

can you buy me one buddy

Zac Price

Here is the last heated debate..

[link=http://www.rcuniverse.com/forum/m_4875136/mpage_1/key_/tm.htm]old post[/link]



Hooper (not a builder, just a guy who "likes to know") compared 3 builders in one day. Answered my doubts.

BB Modss

Good reading in there, This thread is pointless as i see now, No need to upset the rcu balance of good and evil.

juicr

It might make 7hp across the big pond, but not here in the USA!![X(]