glennb2006

Now here is a thought - and this was brought on by the post "max RPMs for a tuned Zenoah".

It seems to me from what I can gather, that most of the tuners use basically the same tool for the job - a Dremel or some similar grinder - die grinders being a favourite.

Now, these tools are fine for one offs, but it seems to me that if you are porting several motors per day or week, then due to the very nature of the tools used for removing material, and the fact that they are hand held, then there are going to be differences and inconsistency.

I'd have thought that someone who had a machine set up to do the porting jobs would have a better chance of getting consistant results.

As much as anything, I posted this to generate discussion - it would be nice to see a response from one of the tuners on this one.

Regards,


Glenn

stuch

Tony at WHH uses machines to do his mod motors. he did one before my eyes it took like 15mins to do all the steps. and then onto the dyno...

OLD_SLOW and in the WAY

from the time i opened a box to the time i put postage on it would take me 8 hours to do an engine by hand. the burr bits will last a long time, hundreds of engines.

MrMikeG

The best builders all hand grind the finishing angles. I have 3 CNC'ed motors, they still needed cleaning up by hand from the builder. Once you have seen the inside of a good motor you will understand why. I doubt too many "Pro-builders" use a Dremel any more, as Larry said "Burr bits last a long time" my guess is he's using a diegrinder.

Scott Schneider

It is not so much an issue of what you grind on ... but HOW and WHERE you grind !!

Unfortunately most novice engine porting attempts done with the Best Of Intentions, ROYALLY screw up the engine unless they have a QUALITY one to try and copy !!

* just making this bigger, that wider and more is better can raise power to some degree, but in most cases the trade off of where in the rpm range the gain is found is not worth the effort when you need a broad usable power spread.

WHAT TOO DO inside a Zenoah has been well documented for years now.
Why do you think we have SOOOOO MANYYYYYY tuners offering the service these days ?

Far too many of these wannabee tuners change something about what they do to prevent being tagged as copy cats, some actually find some power or range for the efforts.
But damn few do anything exotic or special, a lot are still hack jobs being sold too the naive boater trying to save a buck by NOT buying modified engines from tuners who have DOCUMENTED results for there tuning efforts.


Barry Low who works with Craig of swashdrive jets in Australia tried to do multi axis CnC machining of cylinders. results were VERY consistent and good gains in power were found.
But they as many who have tried it soon realize HAND WORK is the ONLY way too do the compound angles required to get MAXIMUM gains in performance.
A combo of machined rough in and hand finishing would be best IMO, but still labor intensive any way you do it !!

Still do ALL my mods by hand, still do more work than others sell, still have as much or more power than needed to win races ..... pay NO ONE for engine work !!

** Do It Yourself !! http://www.modelgasboats.com/Magazin...e_Porting.html

** Or go REAL EXOTIC like this http://www.modelgasboats.com/index.p...=1668&catid=14

glennb2006

Cheers,

interesting to see the comments, I have spent a long time around a lot of two stroke motors (on bikes) and one of the things we spent ages working on was consistency - part of the reason for my posting.

There are always going to be good, and better motors then, from the same builder.

Glenn

martno1fan

I have to agree with Glenn if everyones doing it by hand how do you get consistant results?,what happens on a Friday when your in a hurry to finnish up for the weekend .
Mart

POKIJO

The art of engine tuning/porting is a skill. Not many people have this skill. It makes no difference whether it is monday or friday. Knowing how the measure correctly is also as important as been able to machine the cylinder. Finnishing of a modified engine will always require skilled hand work. I am sure you are not gonna let your dentist put a milling machine in your mouth to accurately fix your teeth. Cylinder modifications are similar, except for the pain of course. Die grinders are only some of the tools used, there are various pencil grinders that are used for specific work and 90 degree dentist grinders used for transfer ports and exhaust port chamfering. Tunsten carbide burs last a long time, probibly longer than the specialist using them. A tuner used to working on complicated multi cylinder engines, will surely have no problem accurately finnishing a little zenoah cylinder whether it in monday or fryday. If he is a specialist, friday will probibly not be the last day of the week. He will still be grinding on saterday. You get what you pay for. This is a fact of life. Chow

POKIJO

Many people have milling machines. Not many have the skill. Or know a good dentist[&o]

martno1fan

My coment was a little tongue in cheak ,but if all mods are done by hand i have to agree with what was said earlier how can you get consistant results ?,are you saying none of the motor modders get one wrong?if you are then i have to say that is impossible.
Mart

OLD_SLOW and in the WAY

when engines are done with CNC you chuck em up flip the switch 10 minutes later they are done and everything comes out within a half a tenth of a thousandth and everybodies happy... you will never understand hand porting unless you been there done that, you get the feel for the burrs cut and have visual and tactile cues you follow. you can come pretty darn close albeit not cnc perfect, but the difference between engines is really neglible, once you've done a few dozen

POKIJO

I agree Old and Slow, The methods of measurement are as important as the grinding.

MrMikeG

I use a degree wheel to set my timings the same. Some people have created blanks they drop in the head to show them the different port timings. Both are good but I know which one is faster! I can do it all with a straight dremel and carbide bit. The last cylinder I did took a couple of hours, then a couple more on the piston. I have some "new" ideas for the next mod, might start on it this weekend!

POKIJO

So you dont grind the transfer ports Mike? Surely, the cnc guys are only cutting the exhaust port, if it only takes a couple of minutes.

MrMikeG

I do the transfers with the degree wheel as well, you can see when they open through the exhaust port. The CNC guys do intake, Transfers, and exhaust on the mill, they even do eyebrows on the transfers! It really is a work of art!