Piston wash patterns

[Canadian farm boy]

What saw is that David?

Looks like an 1125 series stihl to me. I'd guess it's an 036

 

[Canadian farm boy]

A 361

Well crap. At least I was close. Lol

 

[Bigmac]

They were shorties, but top rated JBA Firecone. I was disappointed with the results and expected an improvement in torque.

Less restrictive mufflers, and less restrictive cats made nice improvements across the RPM range.

The failure of the headers still baffles me, but the car sounds and runs better w/o them. (the sound got a bit tinny).

From my understanding long tubes are the only header you want to buy for making power, shorty headers don’t have enough pipe length to the collector, and the exhaust pulses can’t be tuned. Good long tubes can actually gain mid range power. All the testing I have seen with headers say shorty header don’t have much or any gain over manifolds. Try some long tubes!

 

[Bigmac]

2 stroke engines run via scavenging. Different types exist (ie loop, cross, etc.), but without scavenging the engine wouldn’t run. Pipe or not.

Sorry I should have phase my question better, in my mind I was joking, but it sure dose not read that way! Lol In saw motors the can muffler is hindering scavenging so much it is creating carbon build up and a more distinct piston wash. What is the best mods to the muffler to add in scavenging, is a big hole the best thing?

 

[MustangMike]

From my understanding long tubes are the only header you want to buy for making power, shorty headers don’t have enough pipe length to the collector, and the exhaust pulses can’t be tuned. Good long tubes can actually gain mid range power. All the testing I have seen with headers say shorty header don’t have much or any gain over manifolds. Try some long tubes!

Long tubes are not emissions legal (they bypass the cats). The JBA firecone is a patented system, looked promising. However, forced induction changes things, and other SC makers stated that headers did not help their engines even if they helped naturally aspirated ones. You would think it would be the opposite, but I guess the SC likes some back pressure. You just don't know till you try.

 

[J_M____]

Superchargers like very short tube headers that dump into a large collector. Long tubes help scavenge the exhaust when the motor is NA but a supercharger will push the charge out, the quicker it gets out the more power they usually make.

 

[MustangMike]

I think they specifically designed this one, and the tune, for this engine, so it is likely tough to improve much upon it. Ford helped with the tune, making it 50 State legal. They were sold through Ford Performance Parts.

It is an intercooled twin screw. I'm sure a Roots, or Centrifugal, are different yet again.

 

[Moparmyway]

I think they specifically designed this one, and the tune, for this engine, so it is likely tough to improve much upon it. Ford helped with the tune, making it 50 State legal. They were sold through Ford Performance Parts.

It is an intercooled twin screw. I'm sure a Roots, or Centrifugal, are different yet again.

Twin screw is a Roots

 

[MustangMike]

No, Roots has more low end and is more parasitic. They are different.

The twin screw is in the middle, more top end than a Roots, and more bottom end than a centrifugal.

 

[Bigmac]

No, Roots has more low end and is more parasitic. They are different.

The twin screw is in the middle, more top end than a Roots, and more bottom end than a centrifugal.

Didn’t know you car was SC, to bad that cats are so close, but some of the new cats are pretty free flowing! The cats could be hurting collector flow, and making gains hard. Headers at least should help reduce heat in the engine, but if it has NA cam profiles then the overlap might like the back pressure to prevent the boost from pushing fuel/air out the exhaust. And with the cats being close and federal laws, why mess with it!

 

[MustangMike]

The headers were when I still had factory cats, now have Magnaflow and they did improve things. Headers were a PITA to install, so I'm not going through that again. Pleased with the way it runs with the new cats and JBA mufflers, so I'm leaving it be.

The launch, 1st + 2nd are all about how well you can drive it, more power will not help you. On a good road I usually grab well in third, but almost lost if once on a road that wasn't quite perfect.

Although you generally feel "hooked up" in 3rd + 4th you aren't really. If you forget to disengage the traction control, it will shut you down, even in those gears on the highway.

I've got a Steeda suspension in it, so it is very stable and does not feel as insane as the old cars did, but it will build speed deceptively fast, and all of a sudden you are closing in on the car in front of you much faster than you expected.

Steeda Suspension, pan hard bar, 9.5" wheels, clutch, rotors, MGW shifter, Griggs Racing lower control arms and torque arm and pumpkin cover.

Whipple Intercooled SC with small pulley and extra large intercooler reservoir. Comes with Ford Racing tune which is 50 State emissions legal. Drives as nice a stock, just feels like an old fashion build big block when you get into it. Engine also has Eagle steel crank + rods and forged pistons, 4.9 liter (from 4.6).

Runs strong, handles great, is a nice combo of drivability, reliability and performance. With AC, power windows, fuel injection, VCT, multi valves (3) etc you just get a good combination that a tradition muscle car could not provide. This is my daily driver with almost 140,000 miles.

From 60-120, I have even embarrassed crotch rockets (including a Yellow Ducati who promised to annihilate me).

Since it came from the factory with only 300 Hp, it makes a fun sleeper. I've had numerous cars follow me off the highway to ask me what the H*** I had under the hood.

The only race I've lost with it was a 4wd Mitsubishi with 22 psi turbos. W/O drag radials, I just could not launch with him. I had a worked BMW M3 run with me on the highway, but he did not out run me. Whichever car hit it first ended up in front, it seemed we were equal.

 

[Wolverine]

From 60-120, I have even embarrassed crotch rockets (including a Yellow Ducati who promised to annihilate me).

SMH.
I'm picturing you, sitting on you torque peak rolling up to an unsuspecting (squid rider) 600 in top gear...
lmao! W/ bikes it's 80% rider, so you are whooping what we call squids. Congrats.

 

[MustangMike]

I stopped at a gas station, and two crotch rocket bikes (including the Yellow Ducati) came in. The guy on the Ducati said "nice car". I told him it was SCed, and ran pretty strong. He responded he had done over 180 and "I will annihilate you at any speed". I told him 0-60 bikes launch much better, and at high end wind resistance gives the bike an advantage, but at the speeds in between I thought I could give him some trouble.

After some back and forth, he asked if I was headed South, I responded "I am now". We agreed that we would go side by side at 60, he would let me hit it first, and he would blow by me. We did it twice (on I 684), 60-120, he did not go by me either time. Gave me a big thumbs up when we parted. But it is not the only time I have held off crotch rocket bikes at highway speed. My car is tough in that speed range.

If you compare 1/4 mi times of a bike and a car, most of the bikes advantage is in the 0-60 area, in fact, that is usually the entire difference in time.

 

[Moparmyway]

No, Roots has more low end and is more parasitic. They are different.

The twin screw is in the middle, more top end than a Roots, and more bottom end than a centrifugal.

Roots ;

Whipple:


Both twin screw Mike.
I use these types of compressors every day. There really isn’t any difference between them

 

[cus_deluxe]

The headers were when I still had factory cats, now have Magnaflow and they did improve things. Headers were a PITA to install, so I'm not going through that again. Pleased with the way it runs with the new cats and JBA mufflers, so I'm leaving it be.

The launch, 1st + 2nd are all about how well you can drive it, more power will not help you. On a good road I usually grab well in third, but almost lost if once on a road that wasn't quite perfect.

Although you generally feel "hooked up" in 3rd + 4th you aren't really. If you forget to disengage the traction control, it will shut you down, even in those gears on the highway.

I've got a Steeda suspension in it, so it is very stable and does not feel as insane as the old cars did, but it will build speed deceptively fast, and all of a sudden you are closing in on the car in front of you much faster than you expected.

Steeda Suspension, pan hard bar, 9.5" wheels, clutch, rotors, MGW shifter, Griggs Racing lower control arms and torque arm and pumpkin cover.

Whipple Intercooled SC with small pulley and extra large intercooler reservoir. Comes with Ford Racing tune which is 50 State emissions legal. Drives as nice a stock, just feels like an old fashion build big block when you get into it. Engine also has Eagle steel crank + rods and forged pistons, 4.9 liter (from 4.6).

Runs strong, handles great, is a nice combo of drivability, reliability and performance. With AC, power windows, fuel injection, VCT, multi valves (3) etc you just get a good combination that a tradition muscle car could not provide. This is my daily driver with almost 140,000 miles.

From 60-120, I have even embarrassed crotch rockets (including a Yellow Ducati who promised to annihilate me).

Since it came from the factory with only 300 Hp, it makes a fun sleeper. I've had numerous cars follow me off the highway to ask me what the H*** I had under the hood.

The only race I've lost with it was a 4wd Mitsubishi with 22 psi turbos. W/O drag radials, I just could not launch with him. I had a worked BMW M3 run with me on the highway, but he did not out run me. Whichever car hit it first ended up in front, it seemed we were equal.

Just think of all the saws you could buy instead of that silly car stuff mike

 

[srcarr52]

Roots ;

Whipple:
View attachment 141171

Both twin screw Mike.
I use these types of compressors every day. There really isn’t any difference between them

There is quite a bit of difference in internal design, but they package and install about the same.

Screw chargers are much more efficient, especially in higher boost applications and they are more reliable. So of course they cost more.

 

[Wolverine]

The glare kinda messes with reading this picture. After a tank or so I pulled this saw apart to look at wash (was the first and only saw I did transfer work to). I was satisfied with what I saw, looked even enough.

 

[Moparmyway]

There is quite a bit of difference in internal design, but they package and install about the same.
.

Basically roots compresses top to bottom and screw compresses back to front.

Both have twin screws and both discharge from the bottom . Roots might have teflon, nylon, or other seal strips for more efficient operation, but essentially, they both operate by spinning twin screws and compressing air as they squeeze it out.

 

[kingOFgEEEks]

Basically roots compresses top to bottom and screw compresses back to front.

Both have twin screws and both discharge from the bottom . Roots might have teflon, nylon, or other seal strips for more efficient operation, but essentially, they both operate by spinning twin screws and compressing air as they squeeze it out.

I always thought that screw type is just a subset of Roots type. So all screw type superchargers are also Roots type, but not all Roots type are screw type.

 

[srcarr52]

Basically roots compresses top to bottom and screw compresses back to front.

Both have twin screws and both discharge from the bottom . Roots might have teflon, nylon, or other seal strips for more efficient operation, but essentially, they both operate by spinning twin screws and compressing air as they squeeze it out.

The method of compression is different. The key is screw chargers are more efficient, capable of higher boost and have a less pressure fluctuation and the price coincided with the benefits.

I always thought that screw type is just a subset of Roots type. So all screw type superchargers are also Roots type, but not all Roots type are screw type.

Not really. Roots, (sealed or unsealed) have matching profile vanes that are either straight or have a pitch of less than 1 turn for the length of the rotor multipled by the number of vanes so the vane can seal against the house of the blower.

A screw charger usually has vanes with different profiles per screw. The pitch of the vanes are greater than 1 turn per the length of the screw.