BIG BORE POWER ??
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- เผยแพร่เมื่อ 24 พ.ย. 2023
- Testing out an aftermarket Big bore cylinder on our chainsaw. The g366 gets a cheap big bore kit. Will it make any power?
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Id love to see a scientific approach to the benefits of a dremel port job something done without a timing wheel...widen intake, widen exaust, lower transfer work. No significant timing changes, something anyone can do with a cheap dremel set and see if the gains are worth effort...
Without a timing wheel pretty much pointless too do any port work honestly especially if using aftermarket cylinder
@michaelreese4503 I'd disagree... more flow should equal more power. What I'd like to see is a quantitative value for how much more power, while I do have a lathe, timing wheel, pencil grinders ect... I don't have a dyno and I do know that saws I built prior to have all those niceties did seem to gain power but I don't know how much of the perceived gain was actual hp and how much was psychological
@matthewbutcher203 more flow won't help poor timing numbers much is my point also opening up the intake too much will actually loose horsepower I get what your saying but without a timing wheel it's a shot in the dark my opinion
Maybe not without a wheel, as anyone can make or buy a wheel. But, without machining the band and base, as not everyone has a lathe.
Dremel in the rite hands can work miracles. 🙌 . I'm lucky enough to get good results
You know it's going to be a good day when you get to break out the thermal imaging detector And the Play-Doh 😅
Use the thermal camera to determine optimaol run time for piped saws
Went from a 47 to a 54mm cylinder on a dolmar and it was a huge difference, it also went from 64cc to 84cc doing that so you’d expect a lot from that anyway.
I had both and my ported BB was impressive.
You can also clean up the windows in the piston a bit.
Definitely opening up the lower transfers, check port times and a good muffler mod will bring it to life.
Also seems like you could file your rakers down a bit so they get a chance to apply some of that torque in the cut and probably improve cut times. Removing a thicker chip will get you thru the cut quicker, as long as the rpm’s stay above 8500.
Happy Thanksgiving 😜👍
It has a muffler mod on it, as well as a large carb and intake mod.
taking the rakers down might help the big bore time, but would also probably handicap the stock bore, so it could be done once, but makes it kind of hard to do back to back timed cuts
@@DavidBaumgarner well David…if the rakers aren’t low enough, the saw over-revs and timed cuts won’t represent it true potential…kind of like a dull chain.
As for the larger carb, it wasn’t a lack of fuel with the original carb that was holding it back, I know because I built a couple of these too…but thanks for your thoughts.
Hey Red just another future video idea...
I'm sure we've seen it mentioned in "an oil thread" where some old timers and marine/bike racers insist that more power can be had from a higher oil ratio in the mix. I'd love to see that tested in a chainsaw.. maybe a 50:1 vs 16:1 or even higher on the dyno!
It certainly seems like something that would bait a few clicks/views anyways 😁
Excellent video series !!
I made my firewood saw (291) a screamer. It ran awesome. Unfortunately I learned the hard way about the wrist pin retaining clip ears. After many hours one of the ears broke off and wedged between the transfer port and piston destroying my oem cylinder. The 291 isn’t a popular saw so no cheap aftermarket cylinders are available with the new style intake. It’s a big paperweight for now.
One thing I think affects the big bore kit's is lack of case pumping volume to efficiently feed the larger displacement.
Hi Joe, I think the big bore will come around with some port work on the lowers and intake to help flow volume to the upper transfers. Looking forward to the results.
Really cool to watch you play along with this saw.
Amazing content Joe thank you
Great video Great details 😊
Think as you say, the stock BB Transfers limit the flow.... I would open them up to same as stock bore and compare again as a next step.... And then get onto the porting.... Great work as always!
Play-doh aint just for snacking
Thnanks for the info on the carb mod needing to be cleaned out more than not make sense!!
I think you'd get quicker cut times on both cylinders with a little more load on them.
I'll have to try that sometime. Normally just let the saw do its thing with light pressure. Maybe moderate pressure will help speed the cut time
Yeah i would be interested in the same saw dynoed running different oil ratios .
Good job Joe.
Playdough is a handy tool.
Good video joe
Great video!
Joe giving us more and more knowledge with numbers not guesstimation, i have often wondered about these bb kits, did gain some torque especially down low, interesting!
The stock cylinder definitely had more area under the hp curve in the usable power band than the big bore cylinder.
I know it wouldnt really be worth it to chuck it up in the lathe but i think it would be interesting to see the bb with the .018 squish. Doubt it would be a big difference but may be some. Also the timing advance on the 2 compared. I wonder if the advance will help about the same or less. The little experience i have with bb kits and factory the port timing # was usually pretty wildly off so if you did get a oem it would be pretty interesting to see the number differences and wich one did make more power.
I think you'd have to rework the transfers to to bottom to get it making power. Maybe build some external transfers with half a bucket of JB 😊
Nice video! I think you showed alot with the play do comparison as to why there is little to no gain with the aftermarket BB kits. I put a tack on the ported MS361 I am currently felling with and it was spinning at 14,600 rpms, tuned properly. I now have 6 years of production cutting on this saw. Some of my other ms361's range between 14,000-14,400 rpms on average stock and ported. At least with an all oem saw they like the RPMS. I am now looking forward to see how my ported NWP BB kit compares. One thing to be mindful of when doing test cut comparisons is that with every cut a chain gets duller and cuts slower. I like to do test cuts with brand new loops off the same 100 foot roll with the depth gauges set properly with a progressive depth gauge for the wood I am testing in. The C83 usually needs the depth gauges adjusted out of the box for both hard and soft woods. Lacking a dyno myself this has been a more accurate way to test different mods. I generally am making up 8-10 loops of 24" for bucking chains at a time so I use them for testing cuts.
My saw salvage big bore kit on my 039 has something like 60 thou squish so needless to say it was a lemon so I switched back to the stock 029 super kit .….
Thermal camera could ve imolemented to see how a saw reacts to muffler modding. I'd assume a freer flowing muffler doesnt trap heat and the saw runs cooler
Thanks for the comparison
I would be interested in seeing additional stock muffler mods. Enlarging the stock port, bolt on 2nd port (bark box / straight shot), 3 ports.
I wonder what caused that dip in th small cylinders curve right where it should have been making peak power. Without that the big bore isn't close.
What’s all those wiseco pistons in the back Joe?!?
The few times I’ve ventured into “big bore” territory it’s been nothing but dissatisfaction/disappointment. Now a 266/268 to 272 is “technically” a big bore but THAT combo kicks ass with oem jug/slug, oem jug meteor slug and even meteor jug/slug …. Difference in the wood was VERY noticeable-I don’t think folk realize how well the ol gal 272xps can buzz thru the timber ! The China dolls don’t seem to flow as well idk 🤷
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It's almost addictive The way those cylinders resonate with that lyrical ringing sound when you handle them ... What big bore kit are you using ?
That was just a cheap farmertec one.
@@dynojoemods2764 👍
Do you think that the performance would improve with run time? Looks like either setup is a viable option.
It might bump slightly as the rings fully seat in.
is this holzfforma bigbore cylinder? I bought a g660 bigbore kit, port timings were bad and the piston had shorter skirts than the stock one.
You ran this with the base gasket delete right? Would it be worth going a step back and doing a comparison with and without on the bigbore?
The other gained with tighter squish, figured the big bore would like it as well. Seems to be making power high enough in the rpm still raising the ports back up with a gasket may lose power.
Great series Joe! One question though, along similar lines: I have a Stihl 044, & was thinking about getting an 046 piston/cylinder. Will doing this not produce any meaningful gains vs the factory 044? Would porting the 046 cylinder give significant improvements? Thanks!
Only power gain would come from the displacement increase without any porting done. And depending on how good or bad each cylinder is would really dictate which makes better power
@@dynojoemods2764 Thanks!
I believe that with the MS660 the big bore has a shorter skirt piston, and has a problem of free porting when port work or base gasket delete is done. Is it the same with the g366 ?
The g366 appears to have plenty of room till free port. But it is a good habit to check every build.
Wonder what a vp 40/1 94 octane would do in power wise over your pump gas octane.
Not much without more compression and ignition timing. There is some debate on mix ratios and peak power (most refer to marine racing where they found that oil rich fuel could make more power. I'd LOVE to see that tested on the dyno. I may bring that up on the main comment section...
Was that chain sharp? Didn't see many chips compared to the sawdust. Maybe it's just me.
It has some use on it for sure. But I wouldn't call it dull yet. A lot was how the camera was zoomed in and the wind blowing chips around.
One thing I noticed is that the big bore didn't 4 stroke as much, at least that's what it sounded like.
Yeah, she sounded pretty lean, almost screeming. Sometimes the bigger bore wants more fuel? They actually pull harder with more gas, even though they don't have the revs.
The big bore had a slightly different sound to it and seemed to like being just on the edge of lean. But I am fighting a tune issue with this carb/setup.
Yeah, I know you know what you are doing, and know how to tune really good, and have a dyno to prove the tuning anyway. And, I generally like them a little on the leaner side, because they run cleaner. But, I have seen saws that like a lot more fuel too (my dolmar 6100 likes to be fat, something about the reeds and being strato). Thanks, and look forward to some porting.@@dynojoemods2764
How about trying this saw with an 8 pin and see the performance difference
Might have to try that sometime.
What does the upper ports do. Is that where fuel comes out of?
Yes the uppers are where the charge come up through the case.
Halo bos. Mesin nya keren. Apakah mesin itu bisa di perbesar tenaganya.
We will try and get more power for sure
I think you needed to sharpen that first saw
Possibly could use a touch up, but same chain on both.
Yep unless you do pirt work the BB gains nothing!
Every video I've ever seen I read the same comments about the big oil debate. Sorry but more oil hurts the octane rating. Any hod rodder knows when you add compression and timing you need more octane. Not less.
Squish will be over .0020
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