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Seeking 383 propane engine build advice
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<blockquote data-quote="Burbling2500" data-source="post: 1571630" data-attributes="member: 21902"><p>Here is the work order as it stands.</p><p></p><p>Thank you [USER=700]@extremetownie[/USER]. That is inline with my understanding as well. It seams that propane becomes more efficient at the higher compression. Going with stock compression under 10 sounds like it is not optimizing the propane unless there is something in the quench of the d dish Pistons effectively accomplishing this?.. The build is more or less to be a tow for our camper and daily driver so longevity over short term performance.</p><p></p><p>It will have unleaded as a back up cross country when propane isn't an option. It seams 10:1 to 11:1 would be the sweet spot to run either 92 or premium unleaded or propane...the camper also has a 60 gallon automotive tank that serves the camper so really about a 1400 mile combined range without fill with all tanks.</p><p></p><p>No doubt unleaded has been more dialed in over the years and has more btu's for squeezing every bit of performance, but our main goal is economy. Being able to buy a whole year of fuel at a time off season for around $1.99 gallon. Equal to about $2.30 gallon unleaded. The idea is it won't really matter how much market instability occured.</p><p></p><p>The math comes out to about 2-3k in fuel savings annually or maybe 25k in the life of the engine. If the build can be reliable enough to make 200k.</p><p></p><p>So my curiosity on compression ratio. If there is say a 10% loss of the efficiency of propane going from 11:1 to the 9.4:1 that is around 4k in fuel costs not saved. I don't want to push performance and compromise longevity either. End goal is a dry fuel tow vehicle that lasts.</p><p></p><p>Looping back to my original novice question. Is there a reason I wouldn't want the engine builder to get at least a 10:1 compression on a 383 with my application? When I ask him he just says 9.4:1 will do fine because of the quench factor. I'm a novice and maybe there is something I am just missing, but paying 7k cash for the build so definitely want it right.</p><p></p><p>Rock crawler folks like you seam to have the most hands on experience with SBC propane.conversions so I am hoping to either get confirmation that this engine builders plan for compression is sound or be able to share the specific reason of why I want the higher ratio.</p><p></p><p>I can only assume there is something I am missing about another factor of a 383 quench factor that would make higher compression redundant or unnecessary</p><p></p><p>I'm meeting with him tonight to go over the game plan once more before the build. Again, I like this guy. He has over 30 yrs building alt fuel industrial and marine engine and I sure don't want to be an ass, but just hung up on the compression ratio...maybe he assumes we'll end up using unleaded more in the end, but with an onsight 1200 tank and 1,000 mile propane range on board I don't plan to ever use unleaded except the first 5 minutes in cold weather start up.</p><p></p><p>Please advise and thank you again and in advance for any help.</p><p></p><p></p><p></p><p></p><p></p><p></p><p></p><p></p><p></p><p>From my</p></blockquote><p></p>
[QUOTE="Burbling2500, post: 1571630, member: 21902"] Here is the work order as it stands. Thank you [USER=700]@extremetownie[/USER]. That is inline with my understanding as well. It seams that propane becomes more efficient at the higher compression. Going with stock compression under 10 sounds like it is not optimizing the propane unless there is something in the quench of the d dish Pistons effectively accomplishing this?.. The build is more or less to be a tow for our camper and daily driver so longevity over short term performance. It will have unleaded as a back up cross country when propane isn't an option. It seams 10:1 to 11:1 would be the sweet spot to run either 92 or premium unleaded or propane...the camper also has a 60 gallon automotive tank that serves the camper so really about a 1400 mile combined range without fill with all tanks. No doubt unleaded has been more dialed in over the years and has more btu's for squeezing every bit of performance, but our main goal is economy. Being able to buy a whole year of fuel at a time off season for around $1.99 gallon. Equal to about $2.30 gallon unleaded. The idea is it won't really matter how much market instability occured. The math comes out to about 2-3k in fuel savings annually or maybe 25k in the life of the engine. If the build can be reliable enough to make 200k. So my curiosity on compression ratio. If there is say a 10% loss of the efficiency of propane going from 11:1 to the 9.4:1 that is around 4k in fuel costs not saved. I don't want to push performance and compromise longevity either. End goal is a dry fuel tow vehicle that lasts. Looping back to my original novice question. Is there a reason I wouldn't want the engine builder to get at least a 10:1 compression on a 383 with my application? When I ask him he just says 9.4:1 will do fine because of the quench factor. I'm a novice and maybe there is something I am just missing, but paying 7k cash for the build so definitely want it right. Rock crawler folks like you seam to have the most hands on experience with SBC propane.conversions so I am hoping to either get confirmation that this engine builders plan for compression is sound or be able to share the specific reason of why I want the higher ratio. I can only assume there is something I am missing about another factor of a 383 quench factor that would make higher compression redundant or unnecessary I'm meeting with him tonight to go over the game plan once more before the build. Again, I like this guy. He has over 30 yrs building alt fuel industrial and marine engine and I sure don't want to be an ass, but just hung up on the compression ratio...maybe he assumes we'll end up using unleaded more in the end, but with an onsight 1200 tank and 1,000 mile propane range on board I don't plan to ever use unleaded except the first 5 minutes in cold weather start up. Please advise and thank you again and in advance for any help. From my [/QUOTE]
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