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.

 

[Limited02]

Well you answered my question I think if you can round up a stout rotating assembly, P&P your heads, small cams with good valve springs, you should be able to build a stronger and more efficient motor that will more than meet your needs. Bump up to 12#'s and be running low 13's all day

I know what I mentioned sounds easier said than done, but you don't need the bestest of the best for your motor. Just whatever it takes to reach the power you have in mind.

 

[Jakee]

The SBC rod option will be the most cost effective solution and I'll more than likely go this route.

Here's some pics of some powder coated parts I have laying around waiting....

 

[Jakee]

Can you guess what the last pic is for?

 

[Carguy3J]

Can you guess what the last pic is for?

Chevy TPI motor. Duh! That was easy. (watch, now I 'll be wrong.)

 

[Jakee]

Yes, you're correct. Thats the next project that keeps messing with this one. I'll be running twins with a 4 bolt main 350 CI block. The engine is going in a 88 s10 4wd blazer. THe 4wd will be gone but this should be one torque monster and will be a track only set-up. I want to pop wheelies...hehe

 

[mattbreaksthings]

Since this is up top, let me give an update.

I've done nothing but tear the engine down. Everything went on hold right before I went on vacation in California and spent all my money - I'm broke and I'm nervous about spending this sort of money with the way the oil field is right now. I'm not sure when I'll get the opportunity to do this and have considered canning this project and starting a more cost effective approach.

if you DO can it.. i'll me more than happy to take the parts off your hands
-Matt

 

[Carguy3J]

Yes, you're correct. Thats the next project that keeps messing with this one. I'll be running twins with a 4 bolt main 350 CI block. The engine is going in a 88 s10 4wd blazer. THe 4wd will be gone but this should be one torque monster and will be a track only set-up. I want to pop wheelies...hehe

Well, it would get in the way of the wheelie deal, but wouldn't keeping the 4wd help you get all that power to ground and get off the line quicker?

I'm hoping to eventualy build a twin-turbo TPI myself, for an '84 Monte Carlo w/ T-tops, and (when I'm done with it) and aerocoupe rear window. I'm guessing a cage will be a good idea, considering the lack of substantial roof structure. I've also got a '79 Impala 2dr, with the "fastback" style rear glass. I hope to build that into a street-legal Winston Cup look-alike, or at least a real serious road race style car. Of course, that's all after I hit the lottery, or get a decent job. Not sure which will happen first...... lol

 

[Jakee]

I'll post some pics of my friends monte carlo - I think you'll like it.

The 4WD would help get me off the line but I don't think it would hold very long with 600 HP. If I could find an AWD transfer case that would hold up, I would go this route.

 

[techieman33]

Didn't the typhoon have an awd transfer case?

 

[Jakee]

Yes, but it held up to 400HP. Even then, there were problems.

 

[techieman33]

there is always the 4405, but I'm not sure that anyone but possibly troll has run one making that much power.

 

[CDW6212R]

I'd look into the Syclone/Typhoon drivetrain for that S10, Youtube is full of those trucks running very fast and beating high end cars. What about the transfer case is suspect? Those trucks run 13 seconds stock, and it sounds like they see 11's without much work.

 

[pazzo1969]

hey Jake, instead of flooding this post with my pics i'll post the link for your friends. all the turbo pics are on the main page, towards the last 4, like 12 thru 16. excuse the mess, just been to lazy to clean it up. lol mike

http://photobucket.com/pazzo1969

 

[Jakee]

I'd look into the Syclone/Typhoon drivetrain for that S10, Youtube is full of those trucks running very fast and beating high end cars. What about the transfer case is suspect? Those trucks run 13 seconds stock, and it sounds like they see 11's without much work.

Back when these trucks came out, a bud of mine bought one new. I rode with him many times and yes the truck is darn fast. 13 seconds stock and 280 HP (I think). He managed to break the tranny two different times before selling. I'm sure there's something that can be done to make it stronger.

Pazzo1969 - You have a bunch of knowledge in this subject. What's the best tranny option for the 350CI twin turbo'd project?

 

[CDW6212R]

Weren't those the 700R trans? Those I gather have minor issues in stock form, but they can be made to take good power. I think they are the equivalent to the 4R70W trans.

 

[Jakee]

 

[Jakee]

 

[Jakee]

These are all pics of Mike's (pazzo1969) Monte.

 

[CDW6212R]

Very nice, the slick frame too.

 

[Jakee]

FYI - I updated the first post in this thread with 4.0 SOHC assembly instructions, courtesy of ford motorsports. You will need a PDF veiwer to open.