372XPW vs 7900/10 vs ms460/1

[mdavlee]

The transfer tunnels do need to be opened on the 75cc xpw, but do you taper them or hog them out all the way down? No, it wasn't your port work that I have on my saw.

They do need opened up all the way. A 365 special cylinder tunnels are a lot bigger. I can't remember who all ended up with a few of them.

 

[RIDE-RED 350r]

I'll throw in my chit to the conversation.

The 372XP (original) was a fine 70cc saw, the 372XPW did bump the displacement up to almost 75cc, but the transfer tunnels are much smaller. Consequently, it really needed port work to wake it up, and the quality of the port job can vary greatly. Some are fast reving cookie cutters, others have more torque to pull longer bars, some just aren't that good either. Randy has one tip for anyone doing these 372xpw's in his build thread to NOT hog out the transfer tunnels, and I guess he learned that doing so is a mistake. I'm sure there are all kinds of mistakes that can be made in porting that model saw. This is to say, the outcome of the port work can play a large role in this comparison, which is usually a ported 372xpw vs a ported 7900/7910.

I have a 372xpw that was ported by someone who carries a good reputation, and it has more power than my old 372xp, but noticeably only in larger wood with bigger bars. With a 20" bar I can't tell any difference. With a 24" bar in wood it really runs almost the same - it isn't until you lean on it, or have hard wood, or move to longer bars that you can appreciate those extra cc's of displacement. I have a 24" bar on my 372xpw, because I have smaller saws for shorter bars, and larger saws for longer bars. If I had fewer saws I might put a longer bar on the 372xpw. It could handle a 28", and if it were soft wood maybe it could pull/oil a 32", but I wouldn't push it past that.

The 7900/7910 has a slight displacement advantage over the 372xpw, but again, you're really only going to appreciate that in bigger/harder wood with longer bars. If you are putting a 28" bar on both saws and cutting big wood you might be able to appreciate that difference in displacement, but with a shorter bar in smaller wood you likely will not see much difference. On the other hand, if you are planning to use a 28" or 32" bar for big wood most of the time, perhaps a 70-79cc saw isn't what you should be looking at. Personally I'd be looking at a bigger powerhead.

I don't have much experience with the 046/460/461, but you can apply similar analogy there.

A well put statement that I agree with. That large hard maple XP_Slinger and I worked on yesterday with my worked 394 burying a 36" bar and running an 8-pin and he running his worked 372XT with 24: bar and 7-pin really was a good medium to show the muscle the 394 has overt the 372. Now make the wood 20" as opposed to 36" and the difference is lost. Very good point based in reality, very much agree.

As to porting my XPW, mine seemed to come out well, did all the work myself. It is capable of revving at/near 14.5k and still takes to dogging in and leaning on it. Ask XP_Slinger and he will tell you. His ported XT is neck and neck for peak RPM, but the XPW seems to have just a little more grunt to maintain power when dogging in. Weimedog has our saws on one of his videos from about a year ago and the last segment is our two 372's cutting head to head in the same frozen hard maple. What it really came down to was the dang chain, as it often does. For what we were cutting, a brand new loop of full chisel was just a bit too agressive and I found myself needing to hold the XPW back just a little bit and using a bit more finesse.. Josh's chain just happened to be perfect for what we were cutting and when we swapped his B&C to my saw, mine ended up being a little faster... Anyway, I'm rambling on here.

Alot of good conversation here, that 7900/10 sounds like it's tough to beat

 

[RIDE-RED 350r]

FWIW, I opened my transfer tunnels all the way up but did not enlarge the transfer port windows in the cylinder except to raise them. My XPW runs pretty darned strong.

 

[RIDE-RED 350r]

I found Weimedog's vid from our little GTG that day. Right around 17:00 is where my XPW began behaving as it should.

 

[TreeLife]

Port velocity is important! I would be tempted to hog the transfers out and apply epoxy to the walls to create a venturi, and stipple the epoxy. Velocity and turbulence within an intake tract is muy importante! Or so one of my instructors told me haha

 

[RIDE-RED 350r]

Port velocity is important! I would be tempted to hog the transfers out and apply epoxy to the walls to create a venturi, and stipple the epoxy. Velocity and turbulence within an intake tract is muy importante! Or so one of my instructors told me haha

You're absolutely right, velocity needs to be maintained and smooth surfaces in the intake tract including transfers is muy mal. That's is the biggest reason I have not enlarged the transfer port windows in the cylinder except for what occurs in the course of raising them. And why I like to leave an unpolished/somewhat rough surface in the intake and transfers.

 

[TreeLife]

Your theory is accurate but opening up your transfer ports would net your more power up top and you may lose some torque down low. Kinda like a dual plane vs a single plane deal

 

[Deets066]

Bead blasted tunnels is a perfect finish, better than oem IMO

 

[TreeLife]

Bigger ports allow greater volume at the sacrifice of velocity, and vice versa. Big ports: lots of max power and top end. Smaller ports: a more broad power band with a lower hp number.

 

[TreeLife]

@Deets066 when I would build a small block I would have the entire intake manifold media blasted inside and out. Everyone thought I was nuts, I just paid attention in class.

 

[RIDE-RED 350r]

Bigger ports allow greater volume at the sacrifice of velocity, and vice versa. Big ports: lots of max power and top end. Smaller ports: a more broad power band with a lower hp number.

Right. But when we mod our saws for a compression increase, be it a simple BG delete or full on squishband and cylinder deck cutting, we need to raise exhaust back up to around stock timing + or - depending on the saw and builder to try and maintain that peak power.. and from there we need to raise the transfers for a desirable amount of blowdown. You are right about big ports and small ports, but I think there is a certain amount of wiggle room there in the middle and that's where alot of us like to play around.

 

[TreeLife]

Oh no, I understand when you drop the jug you need to readjust the port timing I meant more to extreme degrees of port size as an example. I totally do not know everything about saws and am here to learn! Saws are a lot different than other things I've worked on

 

[mdavlee]

There's gains in the whole power and in bigger transfers. You go too big and when they fall off the peak rpm they can't recover as easy.

On several saws I set transfers first and exhaust height is relative. I've went from 90-102 on 70-90cc saws.

 

[huskyboy]

A well put statement that I agree with. That large hard maple XP_Slinger and I worked on yesterday with my worked 394 burying a 36" bar and running an 8-pin and he running his worked 372XT with 24: bar and 7-pin really was a good medium to show the muscle the 394 has overt the 372. Now make the wood 20" as opposed to 36" and the difference is lost. Very good point based in reality, very much agree.

As to porting my XPW, mine seemed to come out well, did all the work myself. It is capable of revving at/near 14.5k and still takes to dogging in and leaning on it. Ask XP_Slinger and he will tell you. His ported XT is neck and neck for peak RPM, but the XPW seems to have just a little more grunt to maintain power when dogging in. Weimedog has our saws on one of his videos from about a year ago and the last segment is our two 372's cutting head to head in the same frozen hard maple. What it really came down to was the dang chain, as it often does. For what we were cutting, a brand new loop of full chisel was just a bit too agressive and I found myself needing to hold the XPW back just a little bit and using a bit more finesse.. Josh's chain just happened to be perfect for what we were cutting and when we swapped his B&C to my saw, mine ended up being a little faster... Anyway, I'm rambling on here.

Alot of good conversation here, that 7900/10 sounds like it's tough to beat

394's are fast with a short bar too, you'd be suprised. Put a 9 pin and a 20" and hang on

 

[huskyboy]

I read somewhere the 365 top end is better suited to the 372 cases as the case volume better suits the 365 top end, is that true?

 

[Deets066]

I read somewhere the 365 top end is better suited to the 372 cases as the case volume better suits the 365 top end, is that true?

They do run good, @mdavlee

 

[Dolmar Junkie]

Still sitting on one

Anything else in blue?

 

[mdavlee]

They do run good, @mdavlee

They are very good runners. The 65cc top end was first so who knows what cylinder they really had in mind when they designed it

 

[Dolmar Junkie]

What you said about larger bars is absolutely true in my humble opinion. As I cut trees and buck logs for a living, the more I can put out per day means the more money I can make. I worked the saws that the business I work for has (which is a pretty broad range to be honest) and found they weren't enough for me. I decided to bring my 7910 to work one day and strapped a nice 28" sugihara bar with a full chisel chain.

Bucking big wood all day (generally over 24 inches and getting as large as 48 inches where I have been cutting) a capable saw is worth it's weight in gold.

I frankly always thought a 372 was a little down on power compared to other offerings on the market within its size range. Note, this is not me pissing on a husky. I love me some husky saws...but the ms460 to me always had it beat. It was as smooth as the husky with what seemed like more torque.

Going back to my 7910...it had all of them beat for torque and cutting speed. I also found replacing the mounts on the Dolmar to be easy and it looked like a good design from what I saw. I think a whole set of av mounts is like thirty bucks. A single mount on a stihl could cost me as much as I don't get preferential treatment at my stihl dealer and get deals. To be frank I just prefer oem parts for repair, but there just aren't many Dolmar dealers near me and parts can be an issue.

So I guess what I'm saying (from a guy who runs a saw for a living) is purchase what you can readily get service on, or buck up and run a more exotic saw like a Dolly and put up with having to order parts. Do I love my 7910? Yep. Would I rather have a different saw for what I do? Nope.

That stupid Dolmar literally makes my day. The way it cackles and roars all day, how much harder I can pull on the handle thru a log or how how much confidence I have in it while I'm bore cutting a big hardwood. I'm just a big fan of it!

There, I will get off my soap box!
Dominick

Hear,Hear Dominick I think you made me tear up a little with that speech!
The best part of waking up, is a Dolmar in your truck.....

 

[Dolmar Junkie]

I found Weimedog's vid from our little GTG that day. Right around 17:00 is where my XPW began behaving as it should.

I have watched this video multiple times and I will say you guys do have some strong Husqvarnas! (Kind of giving me the itch to go outside in the dark and fire up one of my 288's just to hear it and let the neighbors hear it 2 )