Thread: 3.5 efi vs 3.9 efi

Thanks for the info. What is a seasoned block?

CSK wrote,...

Thanks for the info. What is a seasoned block?

A seasoned block is one that has already been used. In other words second hand.

Ron.

RoverP6B ,First of all what is the blocks composition ? A seasoned block is second hand ? been used ? No , No cigar for that !!
Scientifically ther are reasons a block can get the "seasoned" tag
First one , Number of heat cycles , second one , time stressed , third one stress relieved . by either High heat or Low heat ,
Number of heat cycles , how many times is the engine taken to full operating temp and returned to ambient temp . Number needed , in excess of 5000 (For cast iron)
(if you start and stop your engine 3 timeds a day thats 1500 days or 5 years )
Then theres time stressed , for how long was the engine run to full power and stressed to the same level , A 100 full power runs of 1 min will do the trick,
Then thers Heating or cooling .
Heating the whole block up to around 850C will do a good job of stress relieving , obviously not much good fpr a Alloy block !!!
Then thers the Low temp approach , common;y known as Cyrogenics , its also a method of strees relief .
To understand how these things work you have to some metallurgy knowledge , crystalline structure , carbon content.

400HPONGAS wrote,...

RoverP6B ,First of all what is the blocks composition ? A seasoned block is second hand ? been used ? No , No cigar for that !!
Scientifically ther are reasons a block can get the "seasoned" tag
First one , Number of heat cycles , second one , time stressed , third one stress relieved . by either High heat or Low heat ,
Number of heat cycles , how many times is the engine taken to full operating temp and returned to ambient temp . Number needed , in excess of 5000 (For cast iron)
(if you start and stop your engine 3 timeds a day thats 1500 days or 5 years )
Then theres time stressed , for how long was the engine run to full power and stressed to the same level , A 100 full power runs of 1 min will do the trick,
Then thers Heating or cooling .
Heating the whole block up to around 850C will do a good job of stress relieving , obviously not much good fpr a Alloy block !!!
Then thers the Low temp approach , common;y known as Cyrogenics , its also a method of strees relief .
To understand how these things work you have to some metallurgy knowledge , crystalline structure , carbon content.

That's fair enough. My understanding was based on a converstation with an engine builder some years ago, so although the reference that I made to a seasoned block being used, that may well be necessary but not sufficient in order to accurately describe such a block.

Ron.

a seasoned block as I know it is a good condition second hand block that' s been rebuilt for performance.

the logic is that the block has been heat relieved through operation and is known not to have any defects. This only applies if the engine hasn't been abused or killed via over heating or mechanical damage.

In answer to the original question. Id go the 3.9 and either pin the liners OR do the top hat conversion.

I thought Seasoned meant used
Stress relief is completely different its an actual process carried out on any block new or old as described above

true enough but you can get a brand new block, go through a specific stress relief process lets just say a good heat soak at 850 degrees with an appropriate cool down only to build an engine out of it and find that due to a casting defect one of the support webs (an example only) has a bubble in it that will lead to a fracture when placed under the duress of use.

its an old school thing and with modern casting techniques, metalurgy and non invasive/destructive testing techniques is more or less obsolete.

Originally Posted by Blknight.aus

a seasoned block as I know it is a good condition second hand block that' s been rebuilt for performance.

the logic is that the block has been heat relieved through operation and is known not to have any defects. This only applies if the engine hasn't been abused or killed via over heating or mechanical damage.

In answer to the original question. Id go the 3.9 and either pin the liners OR do the top hat conversion.

If the liner has slipped due to cracked block, will pinning the liners be just as good as the top hat conversion. Also, I bought this thing for 3k and has quite a few electrical woes, body is good and no oil leaks but it still doesn't seem worth it. thats why I was considering getting a used 3.5 efi and just doing a quick motor exchange. The 3.9 to me is evil because of this common flaw of liner issue. Looks like good 3.5efi runners are going for around $1200-$1500. Only going to be used for weekend/camping trips. It all comes down to money. I'm nearly thinking of buying another Rangie with good motor to use as spare parts. I see a few for around the $2000