Effective Compression Ratio is the same as Trapped compression ratio. ECR or TCR. It is when the exhaust port closes. If you raise the E port you are compressing less, so you can make the head...
Type: Posts; User: Mike Wienandt; Keyword(s):
Effective Compression Ratio is the same as Trapped compression ratio. ECR or TCR. It is when the exhaust port closes. If you raise the E port you are compressing less, so you can make the head...
More to think about:
Fuel and compression ratios. I'm assuming most motorheads here are playing with these feature.
If a Gas piston temp is a base, Alcohol piston temp are much cooler so for...
Buy three different brands of pistons for the same model engine.
Measure and record the A,B, C and D dimension. You will find a difference.
Some is due to the different alloys may have different...
Piston Fitting 101 from WPT, Mike Wienandt
Bore in mm 62.28 ,+.020
Stroke mm 55.6
Con Rod Length, mm 111.2
Cylinder # 1 ...
I used to work at Mercury Racing. That is where I learned the system. They used a 30min total on all 2.5 race engines. It was a hurry out the door issue yet verifying everything was going to right...
When doing three cylinder engines like OMC 50 cu or SST60 type engine be carfull of the engine vibration at 4000 rpms. We avoid that rpm.
run 3500 at 3/4 throttle
1 minute idle
3500 at WOT
1...
This is the dyno break used by WPT for Tohatsu Sport C two cylinder.
Break in setup
Main Jets # 220
Spark Advance 1/8 back from stop
Fuel 93
Oil Ratio 16:01
The...
Jeff, here is what i have learned over the 45+ years doing this
Start the engine, verify it is cooling correctly. Only idle as long as it take for general check over. Make sure spark timing is with...
With the water pickup so far back on the torpedo I find it hard to believe you have enough water pressure in positive trim position. Caution
Use water pressure gauge. not less than 15 psi about...
All very important points here.
To convert a modern carb to alcohol is a task. Flushing engine with gas as Rob mentioned is a must. Most fuel pumps won't work for this. That is why Pro engines...
As a rule of thumb, the fuel volume is 2.1 times more than gas. So with the same size carb, the main nozzle and main jet must be increased. A typical gas engine is about 6:1 effective compression...
No OD, Merc racing did not use letters when they issued S/n that I know of. The Mercury Racing outboards were never followed very good in the EPC. You can only look up parts by model, it's not...
The 7 18 03 is the date the engine was made. The S/n is 037625
I wish I knew how to make an attachment, I could supply drawing or photo.
I never make the chamfer to the deck less then 1.400. The real port is lower yet. I don't raise that at all. I leave stock and do all the work with the chamfer. Raising the root of the port kills...
Is that Bridge port or oval port? That's higher than any mod Bridge port I make and if it's an Oval port that's still high even in the middle of the port. Remember the higher you make the port, the...
If you can pull a good prop load at 7800 rpms, I would agree don't shorten it. With the longer pipe it will, get on plane better and have more low end power with the long pipe. you may want to...
No problem Phil. Im going to guess here but I think for best engine performance the tuner length to powerhead should be maintained. For a 20 " would usually be on a larger boat that would require...
Yep you got guys
Are both head gaskets the same quality material. The really old black OMC ones were best but can't get them anymore. As far as the thickness, Check the squish clearance. Don't want less than...
Measure the length from powerhead gasket to the end of the tuner. Make it 1" longer than the SST 60 spec for a V bottom. It will have more bottom end yet rev high enough to make you go fast.
Yes, that sounds like good idea.
The early 56 block was not sand cast. It was permanent mold. The surface was smooth and shaped very well. The proto type engine tested for SST 60 was made of this, but when the engine was...
When milling the head, if you make it very tight spec the head will flex and not hold head gasket seal. That is one reason why I weld the thermostat hole. To give the head strength there. Would...
The SST 45s we build today are 71-73 hp at the crank. Takes some careful details to make that happen. Always on the search for good parts.
The best block for mod engines is the early 56 ci permanent mold block, not the foam block. Bridge port, not oval port . I think about 87-88 I have built with all of them . The transfer ports are...
Was reading one of the other posts, The engine has a bad harmonic vibration that you must avoid to prevent damage of the engine. 4000-4300 it shakes so bad it screws up the fuel in the float bowl...
there are two main kinds of carbs, What I call 2 jet and 3 jet. The 3 jet is from SST 45 and also older 50 ci engines. I have never been able to make 56 ci engine run on the 3 jet carbs correctly.
I have built over 15 national championship winning SST 60s. The last 8 years I have run been about 100 - 102 hp at the crank. We dyno with the exhaust housing and gearcase so we match correct...