Why are some stock engines better than others???
01-06-2006, 07:00 PM
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Why are some stock engines better than others??? For some time I have been trying to grapple with the concept of why some factory staock LS1 engines are slugs and others are absolute rockets.
Having seen many different LS1's on the dyno and seeing the wide variation in base output, I have the following theories:
Production tolerances, i.e. some engines have "better" piston to bore clearances rounder bores etc.
Bearing clearances, some engines have bearing clearances that fall in the correct range of the manufactures tolerances.
Engine balance: some engines have a better natural balance of their reciprocating components.
Some LS1's have good valve spings that do not float, whilst others are just garbage.
Cating quality and core shift: some engines have excellent castings particularly with their heads which maximise runner volume and flow, whilst other are of lesser quality.
Intake and exhaust manifold match, some engines naturally match up better resulting in lessor intake and exhaust restricion.
Although the factory base tunes are pretty much the same in certain cases the tune may be more appropriate to that paticular engine.
And finally running in procedure, ensuring that the piston rings are properly bedded in seems to have a significant impact on the engines final out put as well as oil consumption or lack of.
Other peoples thought on this topic would be appreciated.
Having seen many different LS1's on the dyno and seeing the wide variation in base output, I have the following theories:
Production tolerances, i.e. some engines have "better" piston to bore clearances rounder bores etc.
Bearing clearances, some engines have bearing clearances that fall in the correct range of the manufactures tolerances.
Engine balance: some engines have a better natural balance of their reciprocating components.
Some LS1's have good valve spings that do not float, whilst others are just garbage.
Cating quality and core shift: some engines have excellent castings particularly with their heads which maximise runner volume and flow, whilst other are of lesser quality.
Intake and exhaust manifold match, some engines naturally match up better resulting in lessor intake and exhaust restricion.
Although the factory base tunes are pretty much the same in certain cases the tune may be more appropriate to that paticular engine.
And finally running in procedure, ensuring that the piston rings are properly bedded in seems to have a significant impact on the engines final out put as well as oil consumption or lack of.
Other peoples thought on this topic would be appreciated.
01-06-2006, 10:01 PM
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Thinking obout this some more, the only true way to know would be to obtain two engines one which was high in power and one which was low in power and to strip them and measure up, cc, weigh etc and note the differences, looking for any obvious anomolies that increase/decrease horsepower.
01-06-2006, 11:10 PM
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I ran 13.2 at 108.97 100% stock with a M6 and stock 245 tires. It is a 2000Z28. Very strong stock car. Beat up on many SS ws6 and vetts. The car had 23k miles on it. IMO ls1 perform there best stock around 15-30k and if they are abused their whole life around 70k they realy start to be noticably slower. I babied mine alot and only got on her friday/saturday nights. But then again I only drive it on the weekends.....
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01-07-2006, 12:33 AM
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my car makes good numbers as far as bolt on ls1's go... but at my dealership we have a 99 t/a vert with 245 tires, 2.73 gears and automatic tranny.. and that thing boogies! suprised the hell out of me when i drove it. its bone stock. and its pretty damn good on gas
01-07-2006, 09:48 PM
#16
Some very good info in the original post. I also believe that how the engine was driven while being broke in has something to do with it as well.
About the 70k and the power falling off......I have a friend with a 00 Formula m6 with 101,000 miles on it. It is stock besides an 80 series blowmaster in place of the stock muffler. That's it, no lid, no filter, NOTHING else. I just rode in it and drove it this past week, and it moves. He didn't always own it, so who knows how it was driven or maintained, but I know it runs like a top. With only 36k on mine, I should have a long time before I have to freshen up the ole 346
About the 70k and the power falling off......I have a friend with a 00 Formula m6 with 101,000 miles on it. It is stock besides an 80 series blowmaster in place of the stock muffler. That's it, no lid, no filter, NOTHING else. I just rode in it and drove it this past week, and it moves. He didn't always own it, so who knows how it was driven or maintained, but I know it runs like a top. With only 36k on mine, I should have a long time before I have to freshen up the ole 346
01-07-2006, 10:12 PM
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When I took a tour of the Piper Aircraft Company factory in Vero Beach, FL, this exact question came up when we were walking through the engine building area. For every individual part of the engine there is a person sitting at a table, they check each part for tolerances to make sure they are within manufacturers specs. The bad ones get tossed out and the ones that are within spec all make it to an engine. The guy was saying that some engines that they test are noticeably more powerful. These engines just got a nice batch of perfectly made, perfectly spec'ed parts. The building isn't better from engine-to-engine because thats all done exactly the same. The engines that get parts that are within spec but towards the bad end of the spectrum, are the ones that make the amount of power that the manufacturer wants it to have as a minimum.
Sounds logical to me. So maybe when GM or FORD or Dodge give a car to a magazine to test and than write an article about, they purposely use these perfect parts to build that test car so it its a FREAK.
Sounds logical to me. So maybe when GM or FORD or Dodge give a car to a magazine to test and than write an article about, they purposely use these perfect parts to build that test car so it its a FREAK.
01-07-2006, 10:24 PM
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good thread. i was told one time that on some of the ss's in i think 01 or 02 had some ls6 parts on them, because they ran out of ls1 parts. but i dont know if that is true or not, might be on how hard a person drives there's
01-07-2006, 10:26 PM
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Originally Posted by 2000SLPZ28
good thread. i was told one time that on some of the ss's in i think 01 or 02 had some ls6 parts on them, because they ran out of ls1 parts. but i dont know if that is true or not, might be on how hard a person drives there's
01-07-2006, 10:41 PM
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Originally Posted by Quickin
When I took a tour of the Piper Aircraft Company factory in Vero Beach, FL, this exact question came up when we were walking through the engine building area. For every individual part of the engine there is a person sitting at a table, they check each part for tolerances to make sure they are within manufacturers specs. The bad ones get tossed out and the ones that are within spec all make it to an engine. The guy was saying that some engines that they test are noticeably more powerful. These engines just got a nice batch of perfectly made, perfectly spec'ed parts. The building isn't better from engine-to-engine because thats all done exactly the same. The engines that get parts that are within spec but towards the bad end of the spectrum, are the ones that make the amount of power that the manufacturer wants it to have as a minimum.
Sounds logical to me. So maybe when GM or FORD or Dodge give a car to a magazine to test and than write an article about, they purposely use these perfect parts to build that test car so it its a FREAK.
Sounds logical to me. So maybe when GM or FORD or Dodge give a car to a magazine to test and than write an article about, they purposely use these perfect parts to build that test car so it its a FREAK.
I have heard of factory test cars having hand built engines in the past and that was the explanation as to why they were so quick in acceleration times etc. Maybe an urban myth but who truely knows?