function of load on the eng.

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Try drilling a small bleed hole where the converging cone meets the stinger. I Had exactly the same phenomenon with a blue head 67EXR and the CMB big belly pipe in a rigger, and that did the trick. Credit where it's due - I got that tip from John Finch.
 
Over rev I guess is not the best way to describe what is going on.

The high revs are what I want to make speed.

The problems is that with a prop that is on the edge of not enough load the eng will rev real good.

It is what happens after it gets there that is the problem.

The stinger is at .500 on this pipe. More than enough to let it rev.

It still responds at low speed as in milling up to the line at a ideal and popping off good.

So the stinger is not to big.

Holding heat in the eng with a smaller stinger is just a patch for other problems.

If the burn is good and the ex gasses are at temp smaller stinger dose nothing but choke the eng.
 
How much more is there than a 2167/3?

Thats the problem no props out there that will work in a heat racing boat.

If it was a point and shoot no problem.

But you cant throttle and drive any more prop and have the boat handle the way it should.

You need the revs.

In a big eng you need load to burn the fuel.

Gas props don't work I tried them.

I have hit the wall with the props that are out there.

The pipe is the key I feel.

Many of the Tidewater props that ABC picked up are to small for the power of a good running 1.01.

Andy never ran a 1.01 so he has no testing to go by as most of theses props are his design.

Just slapping a big prop on is not the answer I have tried.
 
No problem with it living. Have bin running the Piston for a year now.

The billet pistons from Scott are the only way to go.

Thy are heaver but after weighing every thing thy brought the eng into balance better.

The vibration that was breaking things is gone.

Have bin running the full complement bearings that I had made for a few months now.

Thy are lasting much longer than any I have run so far.

Ex port timed area can not be made bigger as I run stock ex port with no modification at all.

With out a rod or stroke change it will not happen.

The next step will be the EVO three port ex sleeve.

I have a RS case board out now to fit one.

This will be the next build up.
 
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Stock timing all the way around. 128 132 188

It revs real nice just falls flat half way down the track with the props that let it rev.

H50 6.9 loaded all the way around good. Prop shop 7022 comes off the corner and just screams to top Rs then falls flat on its face about half track. The acceleration is ballistic.

The H50 will pull hard off the corners also but it dose not get near as many Rs.

The H767 I did also performed the same as the 7022

Lost that prop in testing last weekend when the rudder bracket broke exiting out of the conner on a good run.

The B&B stuff just dose not hold up to my boat. This was the second failure.

Andy made a new reinforced bracket for me last week.

Will try a S40 this weekend.

You would have to see it run to understand what I am talking about.

It is really hard to tell till you race other boats how it pulls off the conner.

Static testing by your self will only reveal so much.

The 3 port ex will make it worse with the pipe as it is now that is for sure.

But I think more timed area at the top of the port will lend to better situation for tuning.

Like you said more timed area but in the right place.

Weight will not hurt RPMs. As long as the eng can handle the weight it is not a issue.It will carry momentum thew the corners.

We are talking track racing not saw.
 
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I will try a little more ex and see where it goes.

I just hate to lose all the bottom end I have now.

Real nice to crawl up to the line with your finger off the trigger and have it pop right off.

Try entering turn two with 10 second on the clock and hit the start?

can you do that?

Can you spin out dead stop in the water with a boat stuck on your sponson shake it lose and get back on pipe

with broken boom tubes?

I want it all no compromizes.
 
Well dumb arss added 5 clicks more rudder in between heats to try and move left better.
Never said I could drive the dang thing.
I like coming from the back of the pack also and picking a hole .
Blows every ones mind when I come out of the tails and walk away from the pack.
I will try the higher timing.
But I love that acceleration and it is already faster than the other boats.
Will see at the next race how it goes.
Testing by my self don't tell me a thing.
The gun had it only going 70 on the front stretch at one race.
Some of the boats I race have 89 on the gun.
And I leave them standing.
SO what good is the gun?
That is why I don't talk MPH any more. It is all BS for the key board.
I know its the CF cowl that throws the gun off.

I am also going to try a new front section on the pipe.

The first pipe I had made has a different 3 stage front section on it.

When I get it back from Jerry. I will cut the two apart and put the 3 piece front on the two piece back I have on the new pipe.

This way I can test a shorter front cone with out having a new pipe made from scratch.
 
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Greg Robertson said:
Tom is Right

I think 188 is way too conservative.

I would think 194 - 195 would be more like were you need to be.

My .21 Hydro would do exactly what you described. In fact at 1 point it was faster in the turns than on the straight

If I put more prop on it the launch became an issue.

I raised the exhaust 4 degrees. Made all the difference
Click to expand...
You guys that are running 190 to 195 exhaust duration,is that the full width of the exhaust port ? J.
 
Well I did some checking to make a timing move and what did I find.

Well dumb arss had his head up his you know what the last time he checked the eng.

The numbers are off from what I THOUGHT I HAD.

This thing is at 125,128,186 Did it 5 times and I was dumb founded.

Will cut .015 of the top of the piston and start at 129,132,189 comes to a perfect 30 deg blow down on the program.

Will see what happens now!!!!!!!!!!!
 
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You know what really blows my mind is the power this thing has with theses numbers.

And the RPMs it will run.

Makes me think a little.

Are high timing numbers the answer to a good driving boat?

Or can the right pipe mean more?
 
Ok got it all re-timed.

130,133,190 with 9.2CR and a .90 cc head set at .011 and a flat squash angle.

Will see what happens this time.
 
Its all me in that department.

Now the pipe is a different story.

That is where the power is coming from.

Scott has bin very instrumental in this pipe design with guidance from Andy.

I am just the middle man bringing it all together and reaping the benefits of the testing.

O and Dick keeps it all real for me.

I ask a lot of different people a lot of question and then try every thing.

Testing almost every weekend is the only way to learn what is what.

three years testing this one eng and boat almost every weekend.

I really need to get a life some day.

I love Florida!!!!!!!!
 
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