HO & SO?

Topic: HO & SO? (Read 2816 times) previous topic - next topic

HO & SO?

June 09, 2005, 04:35:07 PM

High Output and Standard Output right? I've theard the terms but could someone tell me what the key differences are? Thanks.

Re: HO & SO?

Reply #1 – June 09, 2005, 06:08:21 PM

cams, heads, intake throttlebody and egr, computer, injectors, i think i hit all of the bases.......

Re: HO & SO?

Reply #2 – June 09, 2005, 08:45:33 PM

Same as above but in the 87 and up sefi engins the HO pistons are forged and have valve reliefs and the SO pistons are cast and have no valve reliefs.

Re: HO & SO?

Reply #3 – June 10, 2005, 08:15:46 AM

What about the bottom end? Are the crank and rods the same?

Re: HO & SO?

Reply #4 – June 10, 2005, 09:57:20 AM

Quote from: thesoldan

What about the bottom end? Are the crank and rods the same?

Yup, crank, rods, block('86-up) are identical....

Here are the differences.

.........HO 225 HP----vs-----SO 150 HP.........
(this applies to SEFI '87-up, See notes at end)

Heads, the HO uses the truck E7TE while SO uses the restrictive E6SE high swirl.

HO pistions have valve relifs, while the SO are flat top

HO has a a cam with more lift and duration than the std 5.0(also different firing order, but both are roller).

The HO inj are 19lb(orange top), while the SO are 14lb(white top)

The HO upper Intake has a larger opening(lowers are identical)

HO has a 60 mm throttle body, the SO is only 50 mm(EGR spacer is smaller as well).

The HO has headers with true dual exausts, while the std 5.0 has cast iron exaust manifolds and single exaust(the '88 Tbird/Cougar used a one into two system with dual lers and tail pipes).

NOTE '86 Mustang (also '86-'87 LSC Lincolns) used the the E6 head and were rated at 200 HP. They also used the flat top pistons, std upper intake, and a unique 58 mm throttlebody. Otherwise the were same as later HO.

Re: HO & SO?

Reply #5 – June 10, 2005, 01:29:31 PM

Quote

SO pistons are cast and have no valve reliefs.

Some of the earlier Flat top pistons were forged as well

Re: HO & SO?

Reply #6 – June 10, 2005, 04:03:28 PM

This is probably a stupid question but how different is a 302 from a 351? I only ask because I'm making plans to buy an engine for rebuilding and really the only reason I'm sticking with 302s is that I have a trunk full of parts for one that were intended for my current engine. I've got head gaskets, valve cover gaskets, intake manifold gaskets, and a set of valve lifters. If I could use any of that in a 351 I'd be tempted to go down that road.

Re: HO & SO?

Reply #7 – June 10, 2005, 04:05:49 PM

I'm not sure but I "think" that all those parts interchange. I know the main difference between a 302 and a 351 is that the bores are different sizes and that a 351 has a taller deck height.

Re: HO & SO?

Reply #8 – June 10, 2005, 04:45:14 PM

I always thought the bores were the same, but the stroke (and deck height) was different. Because of the deck height differences, 302 intakes will not fit on a 351 and vice versa. Your gaskets should fit, but the two rubber end pieces won't, they'll be too short.

Re: HO & SO?

Reply #9 – June 10, 2005, 06:14:47 PM

Since I don't have the dimensions of a 351 handy I'll ask those of you who have done this modification on a similar Thunderbird: how well do these fit? My car has a classic circular air filter, will that have to be replaced for the engine to gain clearance or for that matter will the hood need to be modified?

Re: HO & SO?

Reply #10 – June 11, 2005, 04:23:58 PM

K I found a file with the heights of most common Ford engines and at most the 351 seems to be about 1.3 inches taller than the 302. So I cut the end off a candy box measured at 1.5 inches and placed it on the air filter and closed the hood. Both times it didn't crush or move the box but the presence of grime on the top of the box each time suggests a snug fit. I think I should be alright.

Re: HO & SO?

Reply #11 – June 11, 2005, 05:01:24 PM

you should still be fine. There are several in the user ride of the cool cats section with 460's. They are even taller. At worst you are looking at a k member from a stang that will drop it down an inch or so.

Re: HO & SO?

Reply #12 – June 11, 2005, 10:11:48 PM

Most of the 351 intakes are taller than the 302 piece, so you better add another inch or so to that 1.3".....

Re: HO & SO?

Reply #13 – June 13, 2005, 02:31:16 PM

302 AND 351 same bore different compresion hight. (center of piston pin to top of piston) 302 3.00 stroke 351 3.50 stroke. motor mount are the same but as stated it will be taller. what year is yours if its the 85 and older you can get lowerd mustang motor mounts. you will need different down pipes oil pan intake I know Im forgetting others.

Re: HO & SO?

Reply #14 – June 13, 2005, 04:37:06 PM

Mine is an 83. 302 with TBI.