92 or 102mm Throttle Body on 521ci stroked 496 Merc with Raylar Cool Cap intake
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I agree small restriction. For ultimate power we want less restriction, but.....not sure if there is going to be the desired 20hp in reducing the restriction further. Tuning can become tough with a single throttle blade. Turns into an on/off switch unless linkage is slowed from throttle.
But....maybe worth it, Anybody else do it or are you the guinea pig to find out ?
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I have not found anybody so far that did a 102 mm TB NA.
I loaded all my engine parameters into Performance Trends Engine Analyzer v3.4 and matched my dyno data at 5400 rpm including the 1"Hg intake vacuum. Then adding the 102mm TB dropped the intake vacuum to 0.6"Hg but only netted 7 hp increase. I know of a test on an unstroked Raylar 496 where the TB cfm was essentially doubled and only produced 7.5 hp increase at 5200 rpm. I think SB's reservations and others are likely correct. I am at the point of significantly diminishing returns so will not be pursuing a larger TB set up. Thanks for all the suggestions.
However plugging in a 0.65 lift cam shows a +18hp gain potential so that is still under consideration.
I loaded all my engine parameters into Performance Trends Engine Analyzer v3.4 and matched my dyno data at 5400 rpm including the 1"Hg intake vacuum. Then adding the 102mm TB dropped the intake vacuum to 0.6"Hg but only netted 7 hp increase. I know of a test on an unstroked Raylar 496 where the TB cfm was essentially doubled and only produced 7.5 hp increase at 5200 rpm. I think SB's reservations and others are likely correct. I am at the point of significantly diminishing returns so will not be pursuing a larger TB set up. Thanks for all the suggestions.
However plugging in a 0.65 lift cam shows a +18hp gain potential so that is still under consideration.
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Yes that took me by surprise as well but I am new to high performance engine durability. The 138 psi is based on an average of all eight cylinders. 145 psi highest and 130 psi lowest. The % fuel in the oil has doubled each of the last two seasons from a low of 1.3 % up to 4.5% last time indicating increased blow by as well it would seem. It is a little peculiar that one of my better runs ever was 85.5 mph last spring when BobL and his boating friends were visiting our home lake. This was with the lower compression, only 95% relative HP atmospherics, no bow cover on the open bow and a passenger. Best ever was 89.2 mph just the fall before, 100% relative atmospherics, driver only and bow cover on with the labbed B30.
Really looking forward to see what it will do when refreshed and maybe one or two more hp tweaks.
Really looking forward to see what it will do when refreshed and maybe one or two more hp tweaks.
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Thanks Bob. Yes I am getting a little bored. The refresh gave me the excuse I needed to play around a little to find some more (not to expensive) hp. You know me. I do not want to leave any HP on the table.