4.0 SOHC Performance Motor Build | Page 16 | Ford Explorer Forums - Serious Explorations

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4.0 SOHC Performance Motor Build

I've been helping the mustang crowd come up with a decent set of rods to use in place of the stock forged I-beam rods and I've found a couple different options out there. I want to use this thread for documentation purposes for all the options found and eventually, there will be info about all things needed to build this motor along with the estimated cost. Finally, after the research is done I'm going to put a motor together.


The Objective

A 4.0 SOHC that will consistently hold 500HP and 600HP at the drag strip. (for a decent cost) - in other words, if this can't be done for a certain price, then a different motor is a better option.


Stock 4.0 SOHC INFO

Deck Height 8.858
Bore 3.953
Stroke 3.31
Rod Length 5.748
Piston Pin Height 1.44


Cylinder Bore
Diameter 3.9530
Out-of-round limit 0.0010
Taper 0.0010


Piston / Rings
Standard DIA 3.9520 3.9528
.5 MM OS 3.9716 3.9724
1 MM OS 3.9900 3.9910
Piston to bore limit 0.0012 0.0020
Compression Ring end gap (top) 0.0080 0.0180
Compression Ring end gap (Bottom) 0.0180 0.0280
Oil Ring Snug Fit


Crankshaft and connecting rods
Crankshaft endplay 0.0020 0.0126
Connection rod journal DIA 2.1250 2.1260
Out-of-round and Taper limit 0.0003
Bearing oil clearance (desired) 0.0003 0.0024
Bearing oil clearance (allowable) 0.0005 0.0020
Connection rod endplay 0.0036 0.0106
Main bearing journal DIA 2.2430 2.2440
Out-of-round and Taper limit 0.0003
Main bearing oil clearance (desired) 0.0008 0.0015
Main bearing oil clearance (allowable) 0.0005 0.0020


Valves and related
Intake
valve seat angle 45 Degrees
valve seat width 0.0600 0.0940
valve seat runout limit 0.0020
Stem diameter standard 0.2740 0.2750
stem to guide clearance 0.0010 0.0020
valve face angle 45 Degrees
valve face runout limit 0.0010

Heads
68CC cambered

Camshafts
lobe lift (intake and exhaust) 0.2590
Allowable Lobe lift loss 0.0050
endplay 0.0003 0.0070
Journal DIA (ALL) 1.1000 1.1040
Bearing Inside DIA (ALL) 1.1020 1.1040
Journal-to-bearing (oil) clearance Standard 0.0020 0.0040
Journal-to-bearing (oil) clearance Service Limit 0.0060

Rods

Rod Option 1

The first rod option is a Forged H-beam Manley rod that states it holds 700-800HP on a 4.6 V8. We v6 dudes have to overkill here because 500 HP on a v8 is different for 500HP on a v6.

4.6 L Stroker w/ 22 mm pin and a 2.000" crank journal
Part No. 14044-8
Center-to Center 5.850"
Big End Bore 2.125"
Big End Width .940"
Pin End Width .940"
Pin Bore .8671"
Gram Weight 612


Here is the rod.



With this rod option, the rod journal (big end with the lip) will have to be narrowed by .064" per side. It should only be the little lip you see sticking out. The chamfer will then have to be re-cut and this should be it.

This rod is longer than the stock 4.0 SOHC (Stock is 5.748" and this one is 5.840") this means the custom piston being made needs to have a shorter pin height.

Custom pistons with floating pins will then need to be made to whatever compression you want. These rods go for around $579.50 for a set of 8. This means if you buy 3 set's for a v6, the fourth set is free. Furthermore this means the rod cost per rod will be $72.44 (Not counting the machining cost) If we estimate the machining cost, say 150.00 per set of 8, we come up with $91.19 / rod.

The H-beam rod option already available for the 4.0 SOHC is $125.00 per rod so you can see we've already beat that.

So, to recap this option.

Estimate $91.19 / Rod
Estimate HP the rod can handle is 700-800HP

This should be good for 500HP on the 4.0 SOHC


Rod Option 2

SBC rods.

UPDATE (9-5-2009) - I've decided to go this route for rods. The first option is still available; however, the cost was the deciding factor.

The second rod option is a SBC eagle H-Beam rod that is 5.7" long from center to center. The stock 4.0 sohc rod is 5.748" so this rod is .048" shorter. This means the custom piston being made needs to have a longer pin height depending on the compression desired. The rod journal bore on this rod is 2.1" where as the stock 4.0 SOHC has a 2.125" rod journal. This means the bore has to be opened up. The cost per a set of 8 is lower for this rod ($359.00) so this puts us at $44.87 / rod. The machining cost will offset this and I'll update the thread when I get the info.

The good about this option is the ARP rod bolts are 7/16" where as the first option has 3/8" rod bolts.



Pistons

Compression Ratio for boost

UPDATE (9-5-2009) - I've decided to go with a 9.5:1 compression ratio (custom forged piston) and then get the piston tops coated.

Here is a formula for helping pick a compression ratio for a boosted engine. Anything between 16:1 to 18:1 is what to shoot for on a street set-up. Anything above 20:1 is race car country.

((boost psi / 14.7) + 1) x motor compression = effective compression.

Here is the 4.0 SOHC with 9.7:1 compression running 14 LBS of boost...

Effective Compression
18.93809524

Here is the 4.0 SOHC with 9.5:1 compression running 14 LBS of boost...

Effective Compression
18.54761905

Here is the 4.0 SOHC with 9.5:1 compression running 16 LBS of boost...

Effective Compression
20.25782313

Here is the 4.0 SOHC with 9.5:1 compression running 50 LBS of boost...

Effective Compression
42.69319728
(Okay, this is a little much)


A motor with 8:1 compression running 18 lbs boost VS a 9.5:1 compression motor running 12 lbs boost will have almost the same effective compression and about the same peak power. The big difference will be where you see the power, and how much of a demand will be placed on the supercharger/turbo. Obviously, the 9.5:1 motor is going to have far greater torque and low end power as the boost is only starting to come in. It is also going to be much easier to find a blower/turbo to survive at only 12 lbs of boost -vs- one that would have to put out 18 lbs of boost. It is now very easy to see why a higher compression motor with lower boost is becoming so popular.

Assembly Instructions

Download SOHC_Engine.pdf from FileFactory.com

There's still a BUNCH of work that needs to be done here so this should be considered "A work in progress" until I remove this line from the thread.
 



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I'm not a good camera man, sorry.

IMG_20120331_130508.jpg


IMG_20120331_131056.jpg


IMG_20120331_131132.jpg
 



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That looks very good, and I like the tip.
 












Still have work to do to this tip. I'll surprise you.
 












Jon is on the list. But there is more. I think I watch too much american chopper! LOL

Plus I need a resonator. I've tested the theory and it sounds good. Just have to make it happen now. The turbo on my ride acts like a muffler, the cat (none ceramic) cleans up the sound just a bit, and the resonator takes out the "rasp". So we'll see how this turns out.

But basically, the tip you see (about 6 inches from the end) needs a series of small holes drilled in an orderly fashion, then round bar to give a "rolled" lip appearance, then sound absorbing material, then go over the top of that with the outer shell, which mirrors the tip you see but bigger. The slash cut on the outer will be all the way across and you will see the series of holes from the inside shell (existing tip). So the holes have to be perfectly aligned which I'll have to get done on a mill.

Then I was thinking of getting the entire thing coated in flat black for an army stealth look.
 






Oh man, I'm so sad that moderator "SVO" deleted all his comments cause I could probably gain knowledge from his build... also a little annoyed I just read 13 pages to find out how the stroker 4.0 sohc turned out and there's no answer. I'm looking at attempting 400hp N/A I'll be happy with 370 but I may end up with 320 or so and do like a 5psi boost on it. But with my research I feel like 370 N/A with my plans should be no problem.

And of course I know I resurrected a thread that's been dead for 5 years
 






Performance parts for the SOHC V6 are limited and expensive even though the engine was used in the Mustang. Most Mustang owners upgraded to the V8 rather than modify the V6. The V8 had more potential and did not have the V6 inferior camshaft drive design. The block has limited overbore potential due to thin cylinder walls. When I checked a few years ago a stroked crank was not available and offset grinding of a stock crank was not desirable. A new custom billet crank was around $5,000. For a street vehicle, unless you're wealthy, I don't recommend investing $10K upgrading an interference engine that can easily be destroyed by camshaft timing failure. Gaining power by boost seems the most cost effective method. The stock engine is strong enough to endure a reasonable power increase. If the engine is destroyed due to camshaft timing failure it can be replaced with another stock engine. The performance investment is in the external boost components and the tune.

My performance objective was to have a 4K pound vehicle accelerate briskly at low engine speeds as if it had a V8. That's why I chose to install a roots type supercharger. If your goal is to increase mid to high engine speed power then alternatives are a centrifugal supercharger or a turbo charger. All three options will require a custom tune which can be fairly expensive.

Be realistic in your goals. My criteria for performance improvements was to gain 1 rwhp per $100. I spent about $1K on a high flow intake system (large MAF sensor, large throttle body, custom tune) and gained about 10 rwhp. I spent $1k on a custom high flow exhaust system using the stock exhaust manifolds and gained a measured 10 rwhp increase in max rwhp without losing low engine speed torque. My best investment was to add the M90 supercharger.
 






My 4.0 sohc is a swap into a 1990 ranger. I can assume 207hp factory. Well you've got to factor in egr delete which is probably a couple hp, my high flow exhaust with no cats, no baffled muffler just a straight through muffler with stainless mesh packing. PCV delete reduces hot air in the intake, a/c delete gives a couple more hp.

At this point I assume I'm sitting at 230hp here's my thoughts on upgrades, I plan to dyno after all these upgrades are finished and possibly hit 370-400 n/a

Morana new cast heads $450 (allow for larger porting than stock heads)

Cam regrind for $200-400 or maybe 2 new billet cams if it's not more than $700 very aggressive lobes.

Super six sized stainless valves, maybe round the numbers up for a tiny bit more flow than their stage 3

Local shop to port the heads as far as I can get them, I might cad/cam the dimensions to figure out how far I can go.

Custom aluminum or stainless intake for a larger throttle body and larger ported intake into the heads.

Long tube headers

Might end up going with a larger exhaust even though my exhaust is brand new ( I was shooting for 270hp now I'm shooting for 400)

Accel coil

Granatelli zero ohm spark plug wires

Haven't decided yet if I'm gonna do a stroker motor or not but I don't think I can meet my goal without going stroker. I think if it was a stroker it could increase the cam and head benefits by more than you'd think.

Also since I do not intend to add boost, I'm thinking high compression pistons, plus I already purely run 91 octane, I'm not worried about a high compression motor with no boost.

Larger throttle body ported, polished and knife edged, hour glass shaped throttle plate pin

Electric fan

Underdrive pulley

Now what am I assuming I can get from these mods horsepower wise?

Heads with a super stage 4 port and polish +40-50hp

Nasty aggressive cam, more flow than the super 6 or morana cams available... +40-50hp

Stroked motor + high compression
Could give me another +30-50 maybe more if it mixes just right with the heads and cams

Headers +15hp

Higher flow intake +5-10

Accel coil +5hp

Granatelli wires +2-5hp

Electric fan (motor trend on YouTube proved an electric fan frees up 6hp on a 400hp motor compared to stock clutch fan, so I assume half that) +3-4hp

Underdrive pulley I'm guessing +5-15%

So on the low side that's +140hp before the underdrive pulley that puts me at 370 exactly. My main idea was a budget of $3,000 and assembling it myself and install the motor myself, but if it's a stroker then I feel like it would be very very hard to keep it within a $5,000 budget.

I just like the SOHC, don't try to convince me to do a v8 because this is what I want and I do have the ability to drop $5,000 onto a motor this year if I was really interested in it. I think it's well within reach, I just have to work for it.
 






What I want to do, is take my daily driver that I already have over 200 hours of work into for the motor swap, invest about 2-3 months of paychecks into (since I have zero bills to pay for) and have a motor that has double the output of my daily driver. Then when the motor is finished as it sits on the engine stand in my buddies shop, in one weekend swap it into my daily driver, pop the new tune in, and double my output in a weekend. I dont want to figure out how to put something else in there because I've already done that to put the SOHC in.......

http://www.explorerforum.com/forums...c-iv-ranger-99-sohc-swap-a4ld-to-m5od.455641/

I just want a spare motor and the availability to change the output in a single weekend.

I do not own a garage or a place to put a 2nd vehicle, but one of my best friends will allow me to use his shop for a single weekend, and I'm sure an engine block on a stand for 1 month won't hurt.
 






I also prefer the V6 over the V8 because it fits better in the engine compartment and has overhead cams. I dislike it's unreliable camshaft drive system and the rear location for the right camshaft cassette. I wasn't aware that aftermarket heads are now available. Improved head flow capability will increase upper end power. The stock ignition system is adequate to 6,500+ rpm so I doubt you'll see any measurable gain with the Accel coil. New spark plug wires may help some if your stock wires are old. Most of your proposed mods will increase mid to high engine speed power while reducing low speed torque. What is your goal other than a high hp number? My mods were to increase overall drivability and throttle response while staying with the 5R55E.
 






My goals are
1. Double the engine output (double was just a thought and now it's the goal, I'll be okay if it's 30-80hp less)
2. Do something that's never been done before
3. Build my first performance motor (I've rebuilt a couple of motors back to stock/oem specs but never any major performance mods so I'm looking to learn)
4. See if I can get a better power to weight ratio than my older brothers Lexus sc300 n/a (I believe he has a 2JZ-GE and out of my brothers and I I'll have the fastest daily driven vehicle)
He has a 3500lbs car with 225hp
I have a 3950 or so lb ranger and to overkill his figures I said "double it" which one of my best friends is shooting for 300hp in his vw cabriolet which is a ton lighter I know, but I want to one up his hp figure too.
5. Get that aggressive lopey cam sound I've always dreamt of having since I was a child.
 






Got away from the Explorer for a while, other projects with more potential, and only so much time. Also the ultimate result was a bit embarrassing. Went full out crazy with the 4.0 SOHC NA engine build. Two major caveates, had another well known shop do all the work and it had to appear California emissions legal while passing a smog check. Used Super Six heads, cams and did all of the other typical NA mods from air filter to exhaust exit. Even used a Ford MAF housing and replaced the "tamper proof" bolts and factory epoxy. Looked good but could use more cam. Idea was to get more HP by spinning engine a little faster, get more torque via compression increase.

Now the big dollars. Billet cams or regrinds as no blanks still exist for SOHC 4.0. Couldn't find a pre-existing piston/rod/crank combo that would work. Custom pistons and H beam rods not that expensive (went with I beam) in grand scheme of things. Still had to run on pump gas so stopped compression at about 10.5. Settled on reground cams after talking with cam manufacturer. Predicted that Super Six specs was about all that could be used on street while passing CA smog and inspection. Increased the overlap a couple degrees, duration a few more. Cobbled together a stout set of valves, springs etc.

Engine made just over 300 HP during breakin dyno pull and about 280 lbft torque. All for just over $20k. About what I expected. Now the embarrassing part. Wife had a bad run with cars. Took out 4 of ours in 24 hours. So next day she drove Explorer to work. Lost oil pump and spun a rod bearing getting to side of road. CHP made her move it off of narrow exit ramp to safe location. Goodbye lower end. Flat bedded home 70 miles.

End of my sad story; engine a total loss and new Raptor due out soon, out of desperation and unwilling to divert much more cash to the Explorer I Called Ford. Said they would put in engine with unlimited mileage 2 year warranty for $5000. I said great. 3 months later, they actually get said engine with explanation that none were available remanufactured and had to "build" one. I'll get back to the Explorer drive train sometime, but for now its all stock.
 






Thanks for the update. Sorry about the eventual outcome. Since you've used Super Six heads and cams you can settle a question for me. The SOHC V6 heads have no camshaft bearing inserts. Are there any issues with using the Super Six heads with a stock camshaft? Or for that matter, are there any issues with replacing a stock cam with stripped sprocket retaining bolt threads with a new stock cam? It seems to me that the cam bearing journals will wear the head bores and after a certain amount of wear the head is no longer usable.
 






Yes Joe, thanks for the update, and your efforts with the SOHC engine. Long ago I toyed with the idea of the DOHC 2.9 heads, which a couple of people did get running on the SOHC shortblock. But I wanted more power, and the DOHC heads aren't really much bigger than the SOHC heads, made for the smaller 2.9 engine. The trans is still a weak link, so I pushed that idea aside, and eventually forgot about it.
 






Just a bit to clarify. I don't mean to discourage anyone from building a NA SOHC. Just understand that if its going to be street driven, you are unlikley to get much more power then I did. We came in right at our predicted output.

The heads were SuperSix stage three. Used their stainless valves but the rest of the valve train along with the cam regrid was provided by a well known cam manufacturer through their custom shop. As compared to the SuperSix cams, our final grid had a couple degrees more overlap, slightly more lift and more duration. Looking at Comp cams web site, I see they now offer mild "towing" cams for the SOHC V6. Others may start here or just use the SuperSix regrinds. I also see that SuperSix has streamlined their catalog and offers H beam rods and custom pistons all at "reasonable prices". We used the stock crank shaft, sonic checked, shot peanned and magnafluxed. Then it got a little manual stress relief. Told it should be good to 6500 RPM. Perfect for us since we shifted at WOT at 6200 and completed it by 6300rpm.

It provided a slight burble at idle, not lumpy. Attracted no extra attention from smog guys and still passed using new stock cats in basically stock location (required in CA). Cats were opened up a bit to accept lager exhaust tubing (all mandrel bent). Levels were elevated but within our new stricter limits. If she didn't, I would have added an extra high flow aftermarket 3 way cat down stream of factory cats. It should have cleaned up nicely. Smog legal headers and a combo K&N and Volant smog approved intakes were the only signs of a modified engine.
 






As for the SuperSix cams, we did not use those. We used new old stock cams fresh out of the box. Im told that a cam can be reground once and maintain its durability. I have no tests to confirm nor refute that so after ours were ground and the journals all looked over, we had them heat treated. As to your question, I don't really know for sure. SuperSix says stock cams can be used in their heads. We did use stock cams. Obviously, there is more potential for head wear then cam wear. Then heads were meticulously machined. Careful attention was paid to all aspects of assembly and appropriate lubes were used throughout. The engine was fired, run through a 20 minute breakin procedure, shut down and then had the oil pan and valve covers removed and all accessable bolts torque checked as appropriate. At least that is what was requested of the shop that completed the build.

Would there be unusual wear in the heads? I don't know. No one approached me about any concerns and they talked to me about how I wanted things done a couple times a week.
 






I too have thoughts of grandeur when it comes to a high power 4.0L.
 






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