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.

 

[Jakee]

Shes alive!!!

Are you ready to see a 12.99 pass?

 

[2000StreetRod]

Congratulations!

You've been busy the past month. I'm glad to hear it's running again!

 

[Limited02]

Shes alive!!!

Are you ready to see a 12.99 pass?

Yeehaww!!!! I'm ready to see that pass! You need to mount a camera between the headrest on the passenger seat and record an inside run Basically just raise the headrest, place camera on top of seat and squish the headrest on the camera to hold it. I've tried it and it works great!

I am thinking of going soon myself to try for a 14.99, but not really looking forward to it. They normally run wed and fri nights, but for Nov they are running at noon on the weekends. The temps and DA are much higher at noon than at 8pm, so my chances of improving from last time are slim.

Post up pics!!!!!!!!

 

[Jakee]

Give me some time to get her washed up. There's a years worth of crud on it sitting in the backyard with no cover.

I forgot how sweet the turbo sound is.

 

[Jakee]

The turbo has to come back off. It's smoking and making a noise. I'm not sure what I did wrong during the rebuild but will find out once it's back apart.

 

[Limited02]

The turbo has to come back off. It's smoking and making a noise. I'm not sure what I did wrong during the rebuild but will find out once it's back apart.

Dang it Jake! I told you those bearings were for something

Hope whatever the problem is, it will be a simple fix.

 

[Jakee]

LOL...I thought those were paper weights for the instructions?

 

[Jakee]

The good news is the turbo is fine. I see no damage and everything is right. I'm pretty sure the problem is the oil drain line routing or the pump is starting to go. I'm re-routing and lowering the pump a bit more to make sure there is a gravity forced flow into the pump. STS says you can mount the pump above or level with the turbo but I'm here to tell you that you shouldn't try - you'll have nothing but problems.

 

[2000StreetRod]

drive downhill

Just always drive downhill and the pump will be lower than the turbo. You'll also improve your fuel economy. I'm glad to hear it's nothing serious and I'm confident you'll have the problem resolved soon.

 

[htrdlncn]

Let me know when your going to the track brother!!
Ill be there to cheer you on!

 

[Jakee]

Let me know when your going to the track brother!!
Ill be there to cheer you on!

I found out the track I go to is shut down for the winter. The only other track I'd like to go would be in Baytown. (near Houston)

What tracks are in your area? I might have to make a long haul to get any new times.

 

[Jakee]

Just always drive downhill and the pump will be lower than the turbo. You'll also improve your fuel economy. I'm glad to hear it's nothing serious and I'm confident you'll have the problem resolved soon.

LOL

Yes, the only problem I have with mounting the pump any lower is the turbo is already as low as it gets. So what I'm doing is mounting the pump just above the height of the nerf bars. The pumps protection will be the nerf bar. There will be a potential for something flying up from the front right wheel so I'll have to get creative with a protective cover.


The set-up, before I started revising, worked but I wouldn’t say it worked well. I would get oil in the exhaust side once in a blue moon. It wasn't often enough for me to worry. The reason it did, I'm thinking, is because the pump has always been level with the turbo. I experimented with different sized drain lines (sts recommends 3/8 in cases where the pump is level or higher) but nothing was a permanent fix. So this time it'll get fixed right. (mount the pump lower than the turbo and use -12 size drain line) I may also look at returning oil somewhere near the oil pan VS going into the oil cap like I'm doing now.

 

[htrdlncn]

I have used both Little River Academy and San Antonio Raceway.
Little River is closer but SAR is nicer.
Little River is about 2.5 hours from you and SAR about 3 hours.
Didnt realize you were that far East of here.

 

[Jakee]

I'll look into those tracks. Maybe we can set something up where we can meet at one of the tracks in the next few months.


BTW - It's the pump making the noise. I'll take it apart and see if I got any ARP thread sealer in it. Other than that, I may need another pump.

 

[CDW6212R]

Place your oil return in the lower steel pan, that's easy to work with. I was planning to add an elbow fitting to do that with a bypass oil filter system.

For your truck, is the STS pump there just for the return of the oil? How does the oil get to the turbo, a line from the pressure fitting? I ask because I may one blue moon or so later, do a turbo for mine. I have a steel line mounted in the back of my block to get oil pressure to the top of the block. So I will have oil pressure at the firewall for the turbo, and another pressure sensor.

Are there many choices for that kind of oil pump? The Mallory pump I have as an emergency oil pump to install, it's obsolete and no information exists for it now.

 

[Jakee]

On the drivers side there is a oil pressure sensor. You'll T off this for your pressure oil feed line to the turbo. The pump is used only to return the oil uphill back above the sump level. The reason I don't like the lower part of the pan for an oil return line is it is below the sump level. You really want to be above the oil level for the retun or you'll backfill the line to the pump and beyond when the engine is off.

There are a few pumps that can be used. The STS version is one and a couple more are:

http://cgi.ebay.com/ebaymotors/Turb...p5197Q2em7QQcategoryZ33742QQitemZ110612911936

http://cgi.ebay.com/ebaymotors/Exa-...ptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

http://cgi.ebay.com/ebaymotors/NEW-...ptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

I like the middle one.

 

[CDW6212R]

Thanks for the links, I'll look for those later. So with the noise you have, are you going to be replacing it?

 

[Mountaineer1113]

On the drivers side there is a oil pressure sensor. You'll T off this for your pressure oil feed line to the turbo. The pump is used only to return the oil uphill back above the sump level. The reason I don't like the lower part of the pan for an oil return line is it is below the sump level. You really want to be above the oil level for the retun or you'll backfill the line to the pump and beyond when the engine is off.

There are a few pumps that can be used. The STS version is one and a couple more are:

http://cgi.ebay.com/ebaymotors/Turb...p5197Q2em7QQcategoryZ33742QQitemZ110612911936

http://cgi.ebay.com/ebaymotors/Exa-...ptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

http://cgi.ebay.com/ebaymotors/NEW-...ptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

I like the middle one.

This here is GREAT information for anyone wanting to know where to place the return line on Turbo setups!

Those pumps look awesome. I bet they all perform well but holy hell on the middle one's price. Seems a bit high compared to the other two.

Maybe we should have a sticky somewhere with nothing but Turbo Information... Anyone else think so?

 

[Jakee]

The noise I was hearing was probably the pumps worm gears face rubbing on the bottom cover plate. I opened it and It appears I had the worm gears facing backwards. (there are little stamps on the face of the gear that I had facing up; I reversed this and it's working well so far) I also lowered the pump about 3 inches so I'm not sold the worm gears possible being backwards was even the problem. Just thinking about it, I'm not sure it would even matter which way the gears go on because no matter how you flip them, the angle is the same.

The pump is "broken in" when new by running it dry for a few minutes. During this break-in period, the pump is pretty noisy. It quites down after awhile. Possible because I flipped the gears, I needed another break-in period?

Yeah, I'll get that second pump. I know it's pricy but it has ball bearings and the 10,000 hr rating is darn good too. I’ll have to see how good it is.

I've got to burn all this old gas up before trying to re-tune. Got about 1/4 tank left.

 

[rocket 5979]

The noise I was hearing was probably the pumps worm gears face rubbing on the bottom cover plate. I opened it and It appears I had the worm gears facing backwards. (there are little stamps on the face of the gear that I had facing up; I reversed this and it's working well so far) I also lowered the pump about 3 inches so I'm not sold the worm gears possible being backwards was even the problem. Just thinking about it, I'm not sure it would even matter which way the gears go on because no matter how you flip them, the angle is the same.

The pump is "broken in" when new by running it dry for a few minutes. During this break-in period, the pump is pretty noisy. It quites down after awhile. Possible because I flipped the gears, I needed another break-in period?

Yeah, I'll get that second pump. I know it's pricy but it has ball bearings and the 10,000 hr rating is darn good too. I’ll have to see how good it is.

I've got to burn all this old gas up before trying to re-tune. Got about 1/4 tank left.

The Turbowerx Exapump is one of the best turbo oil return pumps you can buy right about now. Good choice in picking one of those for a replacement. They aren't cheap but you get what you pay for.