Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions

What is the purpose of sleeving the bore of a new engine with cast iron? The ohv Snow King Tecumsehs still have the sleeve while according to my dealer the Briggs Snow Intek does not.

I am aware of sleeving being used to keep in service engines that have been bored to the point that the cylinder walls are too thin. Again,why on a new engine?

Marc 

Small engines starting at -40C and getting warmer needs those cast iron  Cylinder Sleeves why?

Because they have aluminium blocks and it's very important that the piston runs in a iron enviromment.

boblloyd wrote:
I would agree with this.

Throwing more iron into the fire...

I don't have any answers to the issue at hand, but I am throwing in information that may have been used in the companies decision.

Aluminum and steel expand and contract at different rates.  Steel expands/contracts less per degree than aluminum does.  If one had an aluminum piston that gets hot, within a steel bore, the seal/ gap between them might become better as the engine is warmed (assuming tolerances would never allow siezing of the piston).  If one had a steel piston inside an aluminum housing, and subjected it to temp extremes, the seal could be great at startup, but get worse as it is goes 

Also, the rings on a piston are usually steel.  As long as there is no foriegn matter in the upper or lower part of the piston, abrasion wouldn't be an issue; but if foriegn matter got stuck near the rings it would tend to scratch the aluminum housing first.

Depending on the process that was used to create the housing, a cast aluminum may have a porous surface, in turn a machined steel liner would assure a good finish inside the bore.  The Aluminum does disipate heat far faster than would a steel housing.

FWIW,

Walt 

jubol wrote:
Fred,
The only things that are odd are that the information I relayed is from Briggs tech support from a call made late last year, and if you go to the Briggs website Dura-Bore cast iron liner used to be the first thing listed for all the Inteks. Now there is no mention of Dura-bore for the Intek Snow.

Commercial Intek

Residential Intek site

Rob,

Read above, where I refered Mark to the Engine Warehouse.

At their  site, Intek engines spec sheets refer to a cast iron liner, at least 7.5 HP and up.

                                                      Fred

look  at the price for  a short block cast iron sleeve or alum. bore .Big diff  in price .Heat  is inside from combustion  as far as thermel  exspansion  it travels in all directions . Bottom line cheaper to produce.No cast iron sleeve stay away. Just my opinion. and you no what they say about opinions,there like a xxxxx holes every one has one.

millwright

Hi Guys!

Fred-I saw the Small Engine deal last night. The problem is that Briggs Tech Support told me  over the phone the only way to be sure is to check the spec # on the engine . He assured me there are two classes of Intek Snow Engines-One aluminum bore and one cast iron bore. For some reason they have decided not to distinguish the difference accept by spec #. Also interesting to find cast iron  bore Intek Snow Engines on the Small Engine Warehouse list rated at 7.5hp.

The only way to tell is chack for the spec# on the block. While the lists at Small engine warehouse refer to the cast iron models as Snow Intek IC engines if  you click on the picture notice it doesen't say anything about IC on the engines. 

This will all resolve itself next week when I can get a look at the engine. 

Marc

jubol wrote:
I saw that Fred. My confusion comes from Briggs changing it's website, and the information that I got from Briggs. I think Marc should get the model numbers and get some good information from that really knows. It's a lot of money, and it doesn't hurt to be sure.

I saw these that you had posted. There are other 7.5 Briggs on that site with an "essd" at the end that don't say cast iron liner.
SEW 7.5 Briggs

  Rob,

        Some 7.5's do and some 7.5's don't, but all the 8 and above that I checked did have cast iron liners.

Like Richie thinks, OPE Engine makers are blowing smoke!!!

        I've been checking into Tec's OHV engine spec's and found the following.

The Tec 8,9, 10 and 11HP OHV engines have all the same specs.

Same displacement, weight, bore and stroke!! So how are they different? Don't know for sure!

So I have come to the conclusion that Tec and Briggs are controlling HP 3  ways on each engine.

                1. Different Carb's  ( different jets) .

                 2. Different cam shafts.

                 3.The length of time the  intake and exhuast  valves are open, and height of valves when open.

Those 3 things would change the amount of fuel in the cylinder, reduce engine breathing ability and maybe compression slightly, thus changing amount of HP produced.

                                                                      IMHO                                            Fred   

A cast iron cylinder liner is a nice feature on a snow blower, not a deal buster.
*The steel sleeve will finish and wear better than aluminum but in a vertical piston application (like a snowblower)  wear should be trivial. I have seen horizaontal pistion cylinders (like some lawn tractors and RERs) show pronounced bottom side wear perhaps due to gravity.* With reasonable lube maintenance an aluminum cylinder will go the distatnce on a snowblower.
*Aluminum is an excellent conductor of heat hence the "cool bore" trade name.
* It's all about pricepoint and features.  If the OEM wants the cast iron cylinder as a selling point they spec the engine that way. If they want the lowes unit cost they go  all aluminum. I would not say it's all hype since the cast iron bore is a better engine, just not in a significant way for snowblower applications. At some point due to volume or design the manufacture may only offer one or the other on certain sizes.
* The B&S trype number details the specific feature set of an engine while the model describes the major features. The type leads to the governor spring/setting spec and as beat to death in another thread can put the engine in a different HP rate depending where the RPM setting falls on the torque curve and how the calculate out.  That being said 2 virtually identical engines can be selling with different HP ratings. Also like many specifications the advertised number will be something they can consistently meet/exceed. How much tolerance they hold in reseve can be adjusted for a price, or to win a contract.

Pete