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.

 

[Spdrcer34]

Don isn't saying that EVERYTHING has to be custom. Just the brainchild behind the whole engine itself. The Camshaft.

You can buy OTS heads, rods, pistons....everything......BUT to make it ALL work properly, and to get the MOST reliability out of it you SHOULD get a custom cam.

In Don case, he spent about $100 more for a CUSTOM cam that was higher quality, and FAR more accurate in it's advertised events. Guys will spend THOUSANDS of dollars on parts for their motor, and toss in an OTS cam, and then proceed to beat themselves over the head for months on end as to why it's not making the power it should.

Ryan

 

[CDW6212R]

Very well said, these are not $500 motors any longer. The whole cost is not $500-$1000. You are spending $3000 without trouble, and $4000 and more if done right.

Why spend $3000-$4000 and assume that your choice of cam is worth using because it saves $100 or so? The power difference can easily be 75HP, that's expensive HP to waste.

 

[Limited02]

Point taken, if the time ever comes to when I decide to do a cam(cams for me) swap, I'll be sure to give you a shout on your opinion. I know OTS cams are not as good as a custom cam, but I guess it depends on the intended application because sometimes an OTS cam is doable.

So custom for winners and OTS for weiners

 

[Jakee]

CDW6212R - I'm interested in your build-up. Do you have it documented in here somewhere?

 

[CDW6212R]

Hopefully Alex will be an excellent example of an Explorer, to show two different combinations. He is changing the whole engine, and blower, but really it's the head/blower/cam flow potential which he is greatly improving. If you look past the other new parts, concentrate on those three, he is going to be much quicker.

Jake, my engine is a complete longblock from FordStrokers, the heads, cam and rockers came from Camshaft Innovations. I paid to have it assembled completely, so the important cam and valvetrain should be done right. The shortblock was the $1900 version with upgraded "H" rods and forged crank. I paid them for the head gaskets, ARP bolts, flexplate, and pushrods. After the fact I would have skipped the $450 rods/crank, and paid for a Mexican block and link bar lifters. The cost is the same, and the block is the weakest link.

Mine is built for the truck, so I kept the GT40 intake for now with plans to change soon to a blower and different intake. For anyone else doing a 302 stroker, normally aspirated, do not use the common long runner intakes. They are way too restrictive for these engines. The TFS "R" intake is excellent for EFI use, the box top version likely is best for a blower. That's the lower I'm going to get later.

 

[Jakee]

Sounds like you'll be making some good power with that combo. The piping for the turbo is really not as bad as you think. You could run the intake pipe back under the hood depending on where you mount the turbo.

 

[CDW6212R]

Well I'd be satisfied with it right where yours and James is, under the right seat. But it looks really tight just for the turbo pipe going forward. There's only so much room around the frame and the right wheel well.

 

[Jakee]

Yeah, it's tight but If you study the location long enough, it will fit. I wish I would have taken a little more time with mine. Study Mounty's build cuss I think he was on the right track with the mounting. If you do decide to go this route, let me know. I've learned a bunch from doing this and will give you advice on where I feel I went wrong - no reason for you to make the mistakes I made.

 

[CDW6212R]

Thanks, I'll be pondering all along.

I priced some paint today for my cars, ouch red is expensive. The cheap stuff is $200 per gallon, and the top base is $628 per gallon. I bought clear only from Alsa where I got a candy additive. I need to get done what I started long ago. Night,

 

[justin146]

Hopefully Alex will be an excellent example of an Explorer, to show two different combinations. He is changing the whole engine, and blower, but really it's the head/blower/cam flow potential which he is greatly improving. If you look past the other new parts, concentrate on those three, he is going to be much quicker.

Jake, my engine is a complete longblock from FordStrokers, the heads, cam and rockers came from Camshaft Innovations. I paid to have it assembled completely, so the important cam and valvetrain should be done right. The shortblock was the $1900 version with upgraded "H" rods and forged crank. I paid them for the head gaskets, ARP bolts, flexplate, and pushrods. After the fact I would have skipped the $450 rods/crank, and paid for a Mexican block and link bar lifters. The cost is the same, and the block is the weakest link.

Mine is built for the truck, so I kept the GT40 intake for now with plans to change soon to a blower and different intake. For anyone else doing a 302 stroker, normally aspirated, do not use the common long runner intakes. They are way too restrictive for these engines. The TFS "R" intake is excellent for EFI use, the box top version likely is best for a blower. That's the lower I'm going to get later.

I have great hopes of redoing my entire setup this winter and switching to an A/W intercooler. To make more room under the hood, I am going with a spider type intake. This way I can have my intercooler core right on top of the valve cover.

 

[Jakee]

I like the looks of that intake, Justin. Never thought about adapting a carb'd intake.

 

[CDW6212R]

Justin, consider this also, the intercooler is lower and in the center. For a turbo it's easy to mount it this way. The TFS "R" intake is the best non carb style there is, and not much behind the big Victor Jr, and similar big intakes. The lower intake and adapter are the easy parts. The intercooler and upper plenum need the fabrication for the vehicle.

 

[Jakee]

This is what we're looking at if opening up the bore to 4.00"

Stock - New
CID 243.74 - 249.57
Liters 4.0 - 4.1
Rod Ratio 1.74 - 1.77

 

[Limited02]

Just a question, is using a 4.2 V6 from the F150 or even the Windstar an option? The boss has one in his truck and with the 5-speed, it runs pretty good. I thought I have read of guys using the crank in their 3.8's but I am not sure if the 4.0 is in the same family. Just a thought.

 

[pazzo1969]

anymore research jake, kinda been busy i know.

 

[dkchrist]

3.8 based engines are totally different, they have a more common small block bellhousing. I also think that are considerably larger than the 4.0 as well.

 

[Jakee]

Nope - been up on the roof trying to tack shingles on straight.

 

[Limited02]

Get a coil nailer and speed it up!!! What kind of shingles are you using? The Timberline style or the 3-tab kind?

 

[Jakee]

Yes, I've got a coil nailer. The shingles are the 30 year architectural style? (not 3 tabs)

 

[Limited02]

Sounds pretty If I was closer I'd lend you a hand because carpenter work is my thing.

Just to ask, have you ever taken any good pics of the sport with the new wheels? I only saw a rear wheel pic I think.