D-mod 1 2/3 record

[brill27]

how high on porting did you dare to go jerry . did you ever go to far . just wondering shawn brill

[trident]

44 Porting

Yes, my first attempt at a 44 Mod had ports way too high. Very fast, but took two racecourses to get there!

Backed the porting down, it was still plenty fast, and I worked at fattening the power curve from there.

Strong mid range with fast enough on top was my winning package, as I was always way overweight. Needed wide power band to haul my large self...

My preference is maximum port area with moderate port timing.

Jerry

[David_L6]

Wonder how many people today remember Mike Doran , when I started running DMH and EMH in 1970 he was the best in these classes good driver and great eq. they called him Mr clean because his stuff looked so good. I know what his down fall was (never leave a good thing) . He should have never went with those fiber glass Hydro's .

I never met Doran in person but I talked to him on the phone a few times after I bought his last E motor from Floyd Hopkins when he was selling Lee Dingman's stuff. That was one heck of a motor! When I could get the set up right on the right course (I had props for 1 mile courses at about the time that most courses were being set up shorter :-( ) and keep the water leaks patched up (that motor had HUGE ports! - all the way through the water jacket) it was almost impossible to beat. The last time it was raced before I sold it Ralph Cook drove it and he'd never been in my boat before (I was wearing a knee brace and going in for surgery the next week) at an NBRA Short Course Nationals race on my Arltralite hydro and he cleaned house (won 3 of 4 heats and finished 2nd in the 4th heat with a loose needle). I loaned the motor to Ralph once for him to run on his runabout and he won even with a small water leak that was cutting the motor back to 2 cylinders in the turns. The water leaks only affected the motor in the turns - about a third of the way down the straights the exhaust pulled the water out of the cylinder and the motor took off.

There were a few other "trick" things to that motor too but the ports really were HUGE. I talked with Harry O'Brien a few times about the motor and he told me that it was built in his shop so the O'Brien motors that are still floating around out there are probably very similar if not identical to Doran's motor.

[David_L6]

Yes, my first attempt at a 44 Mod had ports way too high. Very fast, but took two racecourses to get there!


Jerry

Your ports must have been VERY high! I know the ports were high in my E motor and Kenny Bayer once told me how his E motors were ported and neither were low. I guess it really is in the set ups and props... Harry Brinkman believed in low but wide ports and the motors he built ran well.

[mercguy]

I am wondering if he built that engine just for records with high porting and no drag. was that a Lonnie engine . an awesome record

nope, definately not a Lonnie engine and not built just for records, as he races the same powerhead alot....they (William's) build their own engines..........

[brill27]

david, the 44 I ran at centrallia was one harry obrian built just before his sight got to bad to do the machining. it has won 6 nationals in apba . vanover in hydro and dunn in runabout. we just keep it fresh and it runs awesome. I remember being the deck rider for mike obrian when I was a teenager . we won nats 3 years in a row. he would run wideopen to the first turn and then half throttle the rest of the laps . awesome horsepower that I have never forgot.

[trident]

44 Ports

Your ports must have been VERY high! I know the ports were high in my E motor and Kenny Bayer once told me how his E motors were ported and neither were low. I guess it really is in the set ups and props... Harry Brinkman believed in low but wide ports and the motors he built ran well.

Well, that depends on what we mean by high. Not to go all Bill Clinton here, what is, is... but those first ports proved too high for good lap times with my weight. Also, fussy to prop. Still, I suspect I was in the range of a lot of other Mod builders. Don't know for sure, they weren't talking...

On a 44, is high, high, compared to 44 service block with 5/8 round ports or compared to the old 55H D ports? Remember those 55H ports were up .060" over the round ports or service ports on both 40 and 44... I ran a lot better with the low port service blocks in DSH, yet the 55H ports clearly had more top end.

When I went down on port timing, and found more area along with better flow through the motor, my speeds stayed high and I gained a lot of midrange, which improved lap times. That proved a winner.

Remember, too, as you raise the exhaust ports you lose effective compression ratio, as nothing compresses until the ports close. This is an issue on a fixed head motor, like the Merc's.

BTW, my APBA and UIM records were ALL set with my 'regular' motors. I didn't have any extra trick higher port motors for big courses. I just ran my best and freshest, pulling big props with carefully worked out setups.

Anyway, enough about what I did, back in the day.

Congratulations to Jason on his new record. Impressive run... loved watching the video.

Anyone who wants to further discuss ports or whatever, just drop me a note.

Jerry

[Sonny]

I've got a question

I went to painstaking lengths to write Harry Brinkmans port diagram out in machine code (G code) spent hours setting it all up and ran it. The cnc machine cut the ports perfectly down to within .0002. When I assembled the motor I noticed that with the piston at top dead center the skirt of the piston was not long enough and a tiny little hole was visible in the lower corners at the bottom of the ports. All of the top engine builders I have talked to say that many are like that and it is not a big deal. There rational is that there is no compression in the front of the house when the piston is at tdc... that is when the vacuum is sucking on the carb drawing in new fuel and that by the time the piston gets high enough to open the crankcase all the sucking is done. the gentleman who was going to help me finish my motor wont touch it because he believes that if the case is open even the teeniest tiniest little bit that the motor is ruined. So.. who is right?

[David_L6]

It isn't ruined. I've had motors like that that ran well.

[Guest]

Free porting the piston

Although the piston clears the bottom of the exhaust ports by a slight amount I agree with David that the engine should run well. If the opening is very slight (a few thousands) you might try to see if you can selectively find pistons with the longest skirt. If the engine is standard bore I could check a bunch of my used pistons to see if it can be closed up.

Alan

[brill27]

Sonny,we have had many engines with uncovered ports . The split second the port is uncovered wont hurt the performace at all. We had a c merc that we cut one port backwerds and it still was fast.98 aof c hydro national champion engine even.

[Larry M]

Did you use the same diameter cutter in all the corners? I always use a bigger cutter in the outer bottom corner so the piston will cover the opening with the bigger radius.

Larry Mac