Chainsaw Porting Theory

[riverrat2]

Absolutely, unless you are cutting at high elevations. Compression increase is a power adder. Too much compression can work against you in a work saw. Work saw I'm classifying a saw saw that runs all day. Not the one truck load firewood cutters. Not your 3 minute YouTube videos.

I'm not saying it's not done, or I am right. I am speaking of my experiences from my uses. The closer I get to 200lbs of cranking compression the more I find tunes change with saw getting to operating temperature. Cold saw it so rich it won't rev up till it gets to temperature.

Saw with closer to 175/185 seem to perform better from start to finish. Make sense?

Stock saws once tuned in, have you ever had to retune once dialed in in same cutting conditions?

Could not agree more 175-190 psi is perfect compression for a work saw

 

[Dieselshawn]

mdavlee: you mean 0 as in engine is dead?

 

[super3]

I think he is referring to winding it all the way around .

 

[jmssaws]

A buddy has a twin turbo 24v that he regularly breaks rods in. Runs good but very hard on parts.

 

[Mastermind]

Randy, on that Poulan I found if you use the metal throat insert and the outer ring from a Stihl ( I don't remember the model I used one from) but it helps. Does it have a 137 or a 164 on it?

Can't recall my friend. I'll check it out.

 

[MustangMike]

My next door neighbor used to run propane injection on his F-350 diesel. Very fast, but could not keep drive trains in it.

 

[MustangMike]

Full Disclosure: I just put a new long block in the Mustang. Running 530 SC hp with the powdered rods in that 4.6 for 119,000 miles, well, they didn't like it, and I put one through the block. I was beating the snot out of it!

Nice to have a Nephew who is a Service Mgr, kept MechanicMatt busy over the last 2 weeks. Feels like new again, but I'm still breaking it in.

It is like my Mother once told me, you earn it in the hundreds, and spend it in the thousands! Oh well, it is nice to have it back! May it last another 119,000!

 

[Dieselshawn]

Jmssaws: something must not be right to be breaking rods in the 24v. Sounds like high rpms or well over 1,000 hp?

 

[MustangMike]

Jmssaws: something must not be right to be breaking rods in the 24v. Sounds like high rpms or well over 1,000 hp?

The 4.6 ltr 3V has powdered rods, and it is well know that this is the weak part of the engine. They use powdered rods in diesels, so they will handle torque, but not RPMs. The rev limiter on these motors is set an an annoyingly low 6,250 RPM. If you are moving in 1st or 2nd, it hits it almost immediately when you punch it. The motor did not come with the SC, we installed it, and I had it at redline a lot more than it liked. It does not owe me anything. You play, you pay!

 

[mdavlee]

mdavlee: you mean 0 as in engine is dead?

When it spins past 4k to the peg it sets on when the engine is off. Fly cut pistons and shaved head with Enterprise Engine cam. Truck had 4.10 gears and 4k gsk kit tight. Thing would make 10-20 lbs of boost in a free rev. Double disc clutch 3rd gear launch was fun with boost.

 

[smokey7]

I realize every saw is different. What I'm starting to wonder is if we can group them by starting timing numbers or quad port or 2 port or husky stratos then old vs new. I'm aware you will never have the perfect combo but will have a better idea of what the trade offs you are making.

 

[Dieselshawn]

Mdavlee: I'm sure lots of 3rd gear boosted launches are fun. I do the same too.

I also get my boost up to 30 psi with a couple of hits on the throttle, then start the clutch in sled pulling while in 3rd high.

Best gear I've ever pulled in.

 

[jmssaws]

Jmssaws: something must not be right to be breaking rods in the 24v. Sounds like high rpms or well over 1,000 hp?

He broke 3 24v rods then switched to 12v rods and is breaking them. 1000hp? I don't know but it's a dually flatbed with chainsaws and a 300 gallon drag tank on the back and it will destroy a good running car. I'm thinking 70 lbs of boost is what's breaking rods. It has a belt drive injection pump also.

 

[smokey7]

Wow that's nuts. That has to be one he'll of a turbo setup and some real hot intake air temp at that much boost!!

 

[Al Smith]

That that goes extremely fast does not go extremely long .

 

[jmssaws]

That that goes extremely fast does not go extremely long .

Well said

 

[mt.stalker]

That that goes extremely fast does not go extremely long .

It will if this is on the hood !!!

 

[junkman]

ahem ...... porting saws ?

 

[jmssaws]

I'm porting right now, anybody else grinding besides me?

 

[srcarr52]

I'm porting right now, anybody else grinding besides me?

Nope, stabbing away at a keyboard, writing Fortran code.