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Topic: HO conversion for SO vs. HO block (Read 2598 times) previous topic - next topic

HO conversion for SO vs. HO block

OK before I start given out facts here in no-way am I and expert in any account. I’m a glorified parts changer at best who tries to do research and the more I learn the more I realize I don’t know. So I am prepared to be scrutinized on this. (But please feel free to input good info will help).
As some of you now I blew my head gasket so I took the time to put on a set of GT40 heads of a 97’explorer and I wanted to get compression up so my hard work goes to you. I found this web-site helps a lot but you must know all you measurements and be careful of your (.points.) and (-&+). http://www.csgnetwork.com/compcalc.html.
Now for the numbers. HO piston call for a -5.5 cc’s due to the eye brows and slight dish in them I don’t know much about SO flat pistons but I believe from listening to you guys there “0”. Now as for the -5.5 on the HO piston I got that # from a book so I don’t even now if that’s accurate enough but it seems close enough. The book also stated that the HO block calls for a .0135 positive piston crown to deck #. But I found that to be wrong in two ways 1 being my engine builder friend said there never out of the factory w/above deck pistons there always below deck and 2 mine was .007 above deck w/ he saw and said some one was ether in there before you or (decked the block) or you have a unique block from the factory. Any way it does prove one thing the book is a guide line and unless you measure your motor you will be wrong.
So the question I’m bringing up here is, is it worth changing the block when converting to HO well I say no if you keeping the stock cam like most of you say the stock HO cam will clear the pistons w/1.6 rockers and give you more then a half point of compression w/ is good for approx 15 more HP. But if you panning on putting in a aftermarket cam you need the eyebrow valve relief’s.

Now here’s a chart that shows you the difference between HO&SO pistons and by keeping the stock 64cc E7 head on either HO block or your SO block. Keep in mind I used the link above w/ “0” for piston to deck clearance and -5.5 for HO pistons and “0” for flattop pistons. These compression ratios are calculated w/a .041 compressed gasket. Keep in mind I used a .039 and gained a ½ cc.

         


Chamber CC’s/   HO pistons  -5.5 cc/   Flattop pistons
64 cc/                                         8.88                                           9.47                                         
63 cc/                                         8.98                                           9.59                                         
62 cc/                                         9.08                                           9.71                                       
61 cc/                                         9.19                                           9.84                                       
60 cc/                                         9.30                                           9.97                                       
59 cc/                                         9.41                                           10.10                                     
58 cc/                                         9.53                                           10.23

HO conversion for SO vs. HO block

Reply #1 –
The pistons are out of the block on my '86 HO block assembly... It came out of a '86 LSC and was virgin. I never did measure them but from the feel, I'd guestimate the slugs are approx .005" out of the hole...

HO conversion for SO vs. HO block

Reply #2 –
That is nice to know about the change in compression. That didn't even cross my mind. I'm still not sure if I want to find some E7's or GT40's and run a stock HO cam on my SO shortblock or if I want to just do the swap. I've been looking around for a Explorer engine for a while now and I think I found what I'm looking for. It's from a '97 Mountaineer with 83K for $450. I haven't called yet but I'm hoping it comes with the intake and injectors. Are those injetors compatible with our harnesses? And does anyone know if the Explorer 5.0's had forged pistons?
GT40p 5.0 w/ vortech @ 9.5psi, 400rwhp

HO conversion for SO vs. HO block

Reply #3 –
The injectors from the Explorer/Mountaineer will work,I'm using a set on my car right now.I don't think the pistons are forged,though.I may be wrong.
'88 Sport--T-5,MGW shifter,Trick Flow R intake,Ed Curtis cam,Trick Flow heads,Scorpion rockers,75mm Accufab t-body,3G,mini starter,Taurus fan,BBK long tube headers,O/R H-Pipe, Flowamaster Super 44's, deep and deeper Cobra R wheels, Mass Air and 24's,8.8 with 3.73's,140 mph speedo,Mach 1 chin spoiler,SN-95 springs,CHE control arms,aluminum drive shaft and a lot more..

HO conversion for SO vs. HO block

Reply #4 –
Well, that's good that the injectors will work and I hope the pistons are forged because I just talked to them today and I'm going to pick it up hopefully on Saturday. And right now I'm opening up another window to order exhaust and an E-303 cam. yeah for me!
GT40p 5.0 w/ vortech @ 9.5psi, 400rwhp

HO conversion for SO vs. HO block

Reply #5 –
Last year of forged pistons in a 5.0 was '92.  All newer Ford 5.0's with factory installed pistons have hypereutectics.....
-- 05 Mustang GT-Whipplecharged !!
--87 5.0 Trick Flow Heads & Intake - Custom Cam - Many other goodies...3100Lbs...Low12's!

HO conversion for SO vs. HO block

Reply #6 –
Oh well, I guess I will have to scratch the plans for a blower.
GT40p 5.0 w/ vortech @ 9.5psi, 400rwhp

HO conversion for SO vs. HO block

Reply #7 –
The 302 god says you are safe to boost 6psi on the hyper(insert rest of that word) pistons.


No I am not the 302 god.
One 88

HO conversion for SO vs. HO block

Reply #8 –
Quote from: CougarSE;120341
hyper(insert rest of that word) pistons.

:laughing:

eutectics.....

:grinno:

and yes you should be fine if you only run 6PSI..


Nick
Quote
there's only about a half a dozen man made objects that are herd by the human ear below 40Hz,a pipe organ,thunder,the space shuttle lifting off,a jet airplane taking off or landing,a large canon,an atomic bomb ignited in your back yard and the heat wave afterward oh wait you would be dead so you would'nt hear it scratch that!,and maybe beating your hear against a wall less then 40 times a second..rap music is'nt one of them!thats 40-60Hz@100+db the moving air is under 40Hz

HO conversion for SO vs. HO block

Reply #9 –
Quote from: 86elan;120212
That is nice to know about the change in compression. That didn't even cross my mind. I'm still not sure if I want to find some E7's or GT40's and run a stock HO cam on my SO shortblock or if I want to just do the swap. I've been looking around for a Explorer engine for a while now and I think I found what I'm looking for. It's from a '97 Mountaineer with 83K for $450. I haven't called yet but I'm hoping it comes with the intake and injectors. Are those injetors compatible with our harnesses? And does anyone know if the Explorer 5.0's had forged pistons?


The only thing ill say be careful about is the GT40 heads have a bigger intake valve so be careful. The E7 we know work from past write-ups and will minus the chamber size by 5.5cc. so I don’t have all the answers and now you’ll  understand how I feel when I say the more I learn the more I can get myself in trouble and the more I learn the more I realize I don’t now.

HO conversion for SO vs. HO block

Reply #10 –
Two words for flat tops.... TRICK FLOW!!!

HO conversion for SO vs. HO block

Reply #11 –
Quote from: Innes;120416
The only thing ill say be careful about is the GT40 heads have a bigger intake valve so be careful. The E7 we know work from past write-ups and will minus the chamber size by 5.5cc. so I don’t have all the answers and now you’ll  understand how I feel when I say the more I learn the more I can get myself in trouble and the more I learn the more I realize I don’t now.


I'm going to use the whole Exploder engine, not just the heads. That engine only has 5k more miles than mine. I ordered the E-303 cam, x-pipe, cat-back, 2400 stall, and I'm working on the headers on ebay. I still need to order the fuel pump, pres. reg, computer, and MAF sensor
GT40p 5.0 w/ vortech @ 9.5psi, 400rwhp

HO conversion for SO vs. HO block

Reply #12 –
Quote from: TurboCoupe50;120457
Two words for flat tops.... TRICK FLOW!!!


Trick Flow heads work with flat tops?
GT40p 5.0 w/ vortech @ 9.5psi, 400rwhp

HO conversion for SO vs. HO block

Reply #13 –
Quote from: 86elan;120544
Trick Flow heads work with flat tops?


Yup... Been running a set on a '86 GT short block for over seven years now...

HO conversion for SO vs. HO block

Reply #14 –
Quote from: TurboCoupe50;120457
Two words for flat tops.... TRICK FLOW!!!

And you have one up on the HO pistons your compression is up. If the chamber size is 64cc you will be approx 9.5.1 small chamber higher your compression and for every ½ point is an additional approx of 15hp.