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.

 

[CDW6212R]

I thought about using a warning light as my indicator but then decided against it since it could be missed when I am in that "highway zombie mode" while driving to work at 0500 in the morning. :

Good thought Rob, a noise is best for some critical warnings.

 

[Jakee]

Good point. And knowing myself, I should probably add 10 buzzers..LOL

then again, anythings better than having the blue smoke tell you your pump is not on.

 

[Jakee]

Changing this…change that…and after more test runs only to see little puffs of smoke out the exhaust (after driving it for awhile)…..the frustration has finally left me and I’m able to apply logic to this. My thought was the worst; the turbo is gone, or worse, I screwed something up when I rebuilt the turbo. But that’s unlikely as when the truck is started and just idling there is no smoke at all. Driving down the road normally there is no smoke. It happens after I’ve been on the highway going over 60 MPH or when I get on it hard. The RPMs raises the oil pressure and the pump is not running fast enough to keep up…It’s not getting the full amps it needs. My volt gauge is lower than it used to be. I don’t know the exact amperage as the gauge is stock. Just that it’s at lower than the middle section of the gauge; something I don’t remember being the case in the past.

I'm pretty sure this is entirely electrical. I’m going to replace the belt first cuss I have a feeling it’s slipping. That smaller ALT pulley has always made me feel uneasy. I’m seeing small traces of rubber in the engine bay around the belt route. If that doesn’t bring the volt meter back up, I’ll replace the alternator. I do have a 130 amp but I may go up to a 150 amp. I do have the elec. Fan, scavenge pump and alpine sucking the volts so an upgrade couldn’t hurt. I’ve traced down all the wiring and confirmed it’s good. I’m for sure going to add a second relay and run it when the boost hits. This will kick the pump on high just like STS does it with their kit. I didn’t do this before because I didn’t understand how to hook two relays up. But earlier in the thread, Don mentioned adding the second relay. It then dawned on me that this is what STS is using to give pull amps to their pump once the hobbs switch detects boost.

Rob – correct me if I’m wrong, but this is how there harness works, correct?

Soo……it just may turn out that the STS pump was still good and I forked out the bucks for the new pump prematurely. Oh well, it’s all good, and I’ve just perfected my set-up a bit more.

 

[Jakee]

Technical note:

When you dump 2 - 3 quarts of oil into your exhaust, and have a borla pro xs muffler, it takes over 50 miles to get all the oil burned out of it. It will trick you into thinking you're still leaking oil into the exhaust, when in fact, you're just still burning the oil from when the relay went out.

So all is good again.

 

[SVO]

.,

 

[techieman33]

wow, what a tease, all those pretty pictures and not one word to give us any details.

 

[SVO]

.,

 

[CDW6212R]

*snicker*

Ah, really it's nothing all that special, just a lil ole 4.7 liter SOHC, with a tad bit of boost

And is a car engine, or is it???!!!!

Very nice, well done. Where did the extra 40 or so cubic inches come from? The pistons and rods don't look a bunch shorter, what is the bore and stroke now?

That'll move a Mustang.

 

[Jakee]

Very nice. Looks like 350 rods, yes? Intake? I give up on that one...

4.7? Okay, so really big bore and stroked? Share details?

 

[SVO]

.,

 

[Jakee]

Wow, someone is really throwing some money at this. Very good. I look forward to the dyno results. Did you do anything with the heads?

What sort of intercooler is being run with this set-up? Does he have Meth injection?

 

[turboexplorer]

Beautiful build! Im excited to hear how well it runs when it gets tuned.

 

[SVO]

.,

 

[SVO]

Does he have Meth injection?

Here, let me help you to the next level, so your not filling your crank case full of H2O

 

[CDW6212R]

Here, let me help you to the next level, so your not filling your crank case full of H2O

Psst, he likes to pump his oil into the exhaust. That water would make white smoke, or gray with the oil.:

 

[Jakee]

Okay, compression ratio this motor is set-up with?

Pumping oil in the exhaust is my specialty!

 

[SVO]

/.

 

[joecrna]

So SVO, you start with a 4.0 SOHC V6, sonic tested and bored it way over, add custom pistons and rods and top it off with a Vortec. Nice!!! Been working up a plan and accumulating funds myself. Was thinking normally aspirated, built bottom end, head work (similar to SuperSix heads) and custom cams. The really hard part, actually two hard parts, is keeping it registerable in CA and finding someone willing to do my wrenching. Any interest? I've talked to many builders. Either no experience (I don't trust their abilities with this engine), or like Saleen, a V6- maybe in a Mustang but not a truck or a truck would be OK if it was a V8. I have the knowledge and ability myself but lack the space and time.

Jake, the work you did at the beginning of this thread has been invaluable to all of us trying to squeeze the SOHC. Many thanks. Even though I can't go turbo, I always gleen significant information from your build threads.

 

[2000StreetRod]

How long will it last?

*snicker*

Ah, really it's nothing all that special, just a lil ole 4.7 liter SOHC, with a tad bit of boost

And is a car engine, or is it???!!!!

A very nice assembly and installation! My concern about investing in the SOHC V6 is the weakness of the rear timing chain guide. Have you found a way to beef up the traction side of the rear guide assembly? The OEM part has no metal reinforcement and can shear off from fatigue.

 

[Jakee]

Sounds good. Good work!

I guess this means it's my turn?