Finally got pics! Reply #30 – November 15, 2011, 03:04:45 AM So let me ask you this. Bottom end is identical, minus pistons, which have less clearance on an s.o. motor, so how could the compression be higher without have smaller chambered heads?I honestly don't belive there is much, if any diffrence in stock blocks other then machining tollerances. I am also curious what cam you cannot run on an s.o. motor, because of the pistons, that you can with stock h.o. pistons. Quote Selected
Finally got pics! Reply #31 – November 15, 2011, 10:01:50 AM If the cam is too big for the SO motor, it will be too big for me anyhow. What is gained by changing firing order besides a need to change PCM? Quote Selected
Finally got pics! Reply #32 – November 15, 2011, 01:41:27 PM Quote from: Haystack;372997So let me ask you this. Bottom end is identical, minus pistons, which have less clearance on an s.o. motor, so how could the compression be higher without have smaller chambered heads?I honestly don't belive there is much, if any diffrence in stock blocks other then machining tollerances. I am also curious what cam you cannot run on an s.o. motor, because of the pistons, that you can with stock h.o. pistons. HO pistons have valve reliefs that are deeper than the dish in SO pistons, allowing better PTV clearance, which allows for bigger cams.. i believe the compression distance is the same on both SO and HO pistons, but the dish in the SO pistons drops the compression .3:1 compared to the HO's Quote Selected
Finally got pics! Reply #33 – November 15, 2011, 01:45:14 PM Quote from: Chrome;373018If the cam is too big for the SO motor, it will be too big for me anyhow. What is gained by changing firing order besides a need to change PCM? the HO firing order produces more power.. i believe it's a 25hp difference, stock cam to stock cam.. like i said, i BELIEVE that's the number, i may be wrong.. i'd have to look it up, but between the small compression jump and firing order change stock to stock, there is a reasonable power increase.. ford detuned the SO for the birds so it couldn't compete with the mustang.. there was a conversation about this on here not too long ago.. lol Quote Selected
Finally got pics! Reply #34 – November 15, 2011, 11:25:04 PM 1987-1988 5.0 HO motors produced 225 horsepower, the 1987-1988 SO produced 150 horsepower / 155 horsepower with dual exhaust in 1988. The tubular headers, e7 truck heads,valve relief forged pistons, better flowing upper intake plenum, bigger throttle body and fuel injectors work with the HO camshaft and computer to produce the 225 horsepower 5.0 HO speed density Mustang motor. Quote Selected
Finally got pics! Reply #35 – November 16, 2011, 12:54:10 AM What I was saying, I have had an h.o. and s.o. piston side by side, and the bottom of the dish was about the same as the h.o. piston top. The ptv clearance is virtally identical between both motors. The power difference is all in the heads(maybe 5-10 hp) intake and throttle body (about the same) cam (10_15) and exhaust (5-10 hp). All of those things working together give you more power. The block has nothing to do with it, because it is the same, minus valve releifs.Also, the same compressiong on a dished piston will create more power then a flat top with valve releifs. I would bet the machining tolerances are bigger then the differences in the piston height. And if you need more clearance in a s.o. block, just add your own valve releifs. Generally the stock h.o. came is close enough in power, that there isn't much reason to throw in a bigger cam. Especially if you have a good set of heads, intake and exhaust. Quote Selected
Finally got pics! Reply #36 – November 16, 2011, 12:56:34 AM Oh, and unless you mill down the gt40 heads, they usually have 64cc heads, and stock is usually around 58cc. So you actually lose compression and gain air flow. Quote Selected
Finally got pics! Reply #37 – November 16, 2011, 01:04:17 AM are you talking about gt40p's or standard gt40's? because the p heads all have 58cc chambers Quote Selected
Finally got pics! Reply #38 – November 16, 2011, 02:15:09 AM Every set I have looked at had the 64cc. Not sure which is which. Quote Selected
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