[Dynamo]

Say Steve, did you ever find yourself a 3.9 to rebuild? I ask because I'm thinking of changing directions with my truck.. If I go the route I'm currently thinking, I'll have a 3.9 and a brand new set of stainless steel headers for sale. Reasonable.

 

[CooperTune]

Say Steve, did you ever find yourself a 3.9 to rebuild? I ask because I'm thinking of changing directions with my truck.. If I go the route I'm currently thinking, I'll have a 3.9 and a brand new set of stainless steel headers for sale. Reasonable.

The weather here has just broken in the last few days. Having been out of the shop all summer I have a few customer cars to address. The 85 degrees is so much better than 100 plus. Sounds as if you are thinking V8 power. I posted my cell phone number on a thread we were chatting on. As much as I hate traveling north with the tolls and traffic we can work it out. Shoot me a text and we can see what can be done. I'm going to stick with V6 power. A 60 degree morning recently my 3.9 was running like a scalded dog. As I mentioned I have the complete cooling system in stock. I hate the thought of crud in the block ending up in the bottom of my new radiator. Thank for thinking of me. I completed one car project over the weekend two more and the Dodge is next. Steve

 

[CooperTune]

Well here I am back at the (Put a V8 in it) Dakota board. Just like so many out there it was not a great year for me. It won't help to complain so I plan to move on. I have spent quite a bit of time looking at what's possible to improve the little 3.9 V6. I have also been collecting info / data trying to figure what causes the running issues I have. I won't bother to list the crazy things the truck has done in the last year. I started this thread thinking a 20 HP improvement would cover my needs. I'm starting to think 50 HP is very doable. I have placed orders for around $2000. in engine rebuild parts. These are all the parts I feel comfortable ordering before stripping the engine down. Every component for the cooling system. After market cam, push rods and roller lifters. Performance timing kit, tensioner plate and performance balancer. Kegger plenum repair kit, oil pump, pickup tube, oil pan and gaskets complete. Tower bushing, dizzy drive, distributor and Performance coil.

Once I've stripped the core engine and check the head, block and crank for cracks. I understand heads are common to crack, if that is the case I'll order new bare castings. Local machine shop can sonic test the block and I'll bore as large as block will safely handle. Thinking about using 318 floated pistons and a set of V8 Scat aftermarket rods thinned down to work with split pin crank. Already have the SS headers and 3 inch exhaust system. Wish me luck I'm in for a dime in for a dollar. Steve

 

[arrow]

I don't blame ya for playing with the 3.9. I'll be curious to see if you can begin to match hp with a regular 318. Heads will be huge in your endeavors so anything you do to improve flow in this regard will pay off big.
The thing that drove me nuts with my 91 3.9 were cam sensor issues.
Just putting headers on and using 3.91 rears woke up the truck considerably.
Good luck and keep us abreast.

 

[CooperTune]

Thanks, I have been thinking about this project for some time. As we know there is little the aftermarket does for this engine. Hughes Engines do or did offer a mild camshaft that works with the PCM. They also offer a plenum repair kit to seal the manifold. I degree every camshaft I install so a performance timing kit. Also the spring cap and keeper kit to handle additional lift.
I replaced cam sensor and had to have a shop put it on computer and we adjusted just like you do any dizzy. I'm fairly sure my timing chain is badly stretched. Anyway all parts should be here Thursday. Steve

 

[arrow]

Thanks, I have been thinking about this project for some time. As we know there is little the aftermarket does for this engine. Hughes Engines do or did offer a mild camshaft that works with the PCM. They also offer a plenum repair kit to seal the manifold. I degree every camshaft I install so a performance timing kit. Also the spring cap and keeper kit to handle additional lift.
I replaced cam sensor and had to have a shop put it on computer and we adjusted just like you do any dizzy. I'm fairly sure my timing chain is badly stretched. Anyway all parts should be here Thursday. Steve

You may also consider 1.7 rockers to get a bit more lift and a slight duration bump. All of this will depend on head flow as to viability of performance adaptations.
I know a few guys who installed stroker kits and were disappointed w the results mainly for failing to regard any symbiotic relationship to the rest of the engine.
You can also cut the heads some and use thinner head gaskets to increase compression.

 

[CooperTune]

I enjoyed chatting with the guy at Hughes Engines. It seems they at one time offered stroked cranks. I have read what I can find on V6 design issues. Having spent a life time building inline 4 cyl engines, natures worst balance design. It seems just about every V6 design takes a different path to deal with the balance issue. I hope to visit the only somewhat local shop with bob weights for a V6 crank. There seems to be some question as to percent of reciprocating mass used for bob weights. I'm very happy with the smoothness of my current engine. I'll pick up a core tomorrow and begin stripping it to see what I have. I have heard from local machine shop the heads are prone to crack. I expect chamber cracks so I'll pull valves wire brush, check with magnet and dust. If cracked, deep valve seats or wrapped I'll order new casting, may anyway. Weather new or used mild port matching, bowl work and a little around the guide bosses. Correct seats with the Serdi setting angles and margins. A little back angle on the valves (all new) correct springs, caps and keepers. New mild performance cam, roller rockers, push rods and rockers with pivots. I have in the past used extended rockers on engines and found improvement at upper end of RPM at expensive of bottom end. With a 3.55 CWP I'll try and keep my low RPM torque up.
Parts are showing up all day.

I'm sure it is clear this is not a cheap thing to do. Went to the Dodge dealer looked at new Ram $84,000. Makes me feel much better about spending $4000 to repower my ride. Even if I end up spending another $1700. on a remaned 5 speed I'm good. Steve

 

[arrow]

I enjoyed chatting with the guy at Hughes Engines. It seems they at one time offered stroked cranks. I have read what I can find on V6 design issues. Having spent a life time building inline 4 cyl engines, natures worst balance design. It seems just about every V6 design takes a different path to deal with the balance issue. I hope to visit the only somewhat local shop with bob weights for a V6 crank. There seems to be some question as to percent of reciprocating mass used for bob weights. I'm very happy with the smoothness of my current engine. I'll pick up a core tomorrow and begin stripping it to see what I have. I have heard from local machine shop the heads are prone to crack. I expect chamber cracks so I'll pull valves wire brush, check with magnet and dust. If cracked, deep valve seats or wrapped I'll order new casting, may anyway. Weather new or used mild port matching, bowl work and a little around the guide bosses. Correct seats with the Serdi setting angles and margins. A little back angle on the valves (all new) correct springs, caps and keepers. New mild performance cam, roller rockers, push rods and rockers with pivots. I have in the past used extended rockers on engines and found improvement at upper end of RPM at expensive of bottom end. With a 3.55 CWP I'll try and keep my low RPM torque up.
Parts are showing up all day.

I'm sure it is clear this is not a cheap thing to do. Went to the Dodge dealer looked at new Ram $84,000. Makes me feel much better about spending $4000 to repower my ride. Even if I end up spending another $1700. on a remaned 5 speed I'm good. Steve

Your intake quits around 4200 RPM. It is strictly designed for low end torque so increased ratio rockers won't hurt and will liven up the entire rpm range.
The infamous cracks you allude to seem to happen more to V8 heads.
I have a set of heads taken off my R/T and at 36K, they are crackless. I think some of these "crack" issues have gained a rather urban legend. They weren't cracked on my 318 with 156K on it either.

 

[CooperTune]

Thanks for your input. I made a quick run to Pa yesterday to pick up my core engine and SS headers from a fellow board member. It was fun to meet someone with interest to match to help each other out. Can't wait to get it on a engine stand and start pulling parts. The throttle body will come off and go out for mods, I'm thinking this will have better result than going to the V8 TB directly. The Hughes Keg plate has arrived so the Keg will receive attention. I'm still reading about Keg mods. I don't expect to get a lot out of Keg and TB but each small improvement will pay off. I think I started a thread on cyl head porting. I'll look around for it I'd like not to reinvent the wheel. Steve

 

[arrow]

Thanks for your input. I made a quick run to Pa yesterday to pick up my core engine and SS headers from a fellow board member. It was fun to meet someone with interest to match to help each other out. Can't wait to get it on a engine stand and start pulling parts. The throttle body will come off and go out for mods, I'm thinking this will have better result than going to the V8 TB directly. The Hughes Keg plate has arrived so the Keg will receive attention. I'm still reading about Keg mods. I don't expect to get a lot out of Keg and TB but each small improvement will pay off. I think I started a thread on cyl head porting. I'll look around for it I'd like not to reinvent the wheel. Steve

Don't waste time or money on the keg. The mods I've seen on kegs which began between 190-192 cfm were improved to a best of 194.
There is simply a wasteland for intakes for these Magnum engines.

The Mopar TB for the Magnums start off at a certain size. On my R/T it started at 50mm at the opening and taper reduced to 47mm at the intake side. There is more to it than gross air flow. I forget what the 6 cyl tb starts off at (46mm?). I'm thinking the 6 cyl tb might do the same if not altered. After you're done with the engine, the V8 tb may be perfect.
I Switched to a 52mm Fastman with heads, intake, cam and exhaust changes.

 

[CooperTune]

It's a new day now, I started stripping the core engine yesterday. Having come from up North it shed a bunch of rust scale in my truck bed. After spraying it down with PB Blaster/ WD 40 and high pressure air it looked better. The old " you can't judge a book by the cover" is still true. The TB is dirty underneath. The Keg is very clean inside viewed though the TB bores. I have worried about the timing chain on my engine but this one seems very tight and the rails and gears show no wear. It's beginning to look like someone may have been in this engine before. The water pump appears almost new. I had concerns about the timing cover and water damage to it. Glad I didn't order a new one this one is perfect cleaned up. Removed one cyl. head and was surprised at the size of the pistons and valves. While I did not remove the valves to mag seats I did wire brush between the valves and see nothing to concern. The bores on that side show no cyl. wall wear and the hone marks are still faintly visible well up the walls. I noticed the flat top pistons and a slight chamfer and look to be .050 down the bore. I have been looking at aftermarket rods and pistons for this job. Scat offers floated rods with ARP and come 8 to a set. My plan is to buy a set machine them for the correct side clearance and notch for V6 bearing tangs. Searching around KB offers a 318 floated pistop flat top with valve reliefs which is listed wit .050 more pin to deck height. The valve reliefs hold 5 CCs so some math will be required to figure the best way to come up with 10 to 1 CR over the current 9 to 1 CR. While the core was a std tranny unit the flywheel is not with it. If some one has a 3.9 flywheel to sell or trade please let me know. I have ordered a new ring gear so gear condition not a big deal. Looking forward to getting this project done, I take lots of pictures. I can text them to a phone. I have not figured how to post them here yet. If someone want to post them for me I'll be glad to share. Steve

 

[arrow]

It's a new day now, I started stripping the core engine yesterday. Having come from up North it shed a bunch of rust scale in my truck bed. After spraying it down with PB Blaster/ WD 40 and high pressure air it looked better. The old " you can't judge a book by the cover" is still true. The TB is dirty underneath. The Keg is very clean inside viewed though the TB bores. I have worried about the timing chain on my engine but this one seems very tight and the rails and gears show no wear. It's beginning to look like someone may have been in this engine before. The water pump appears almost new. I had concerns about the timing cover and water damage to it. Glad I didn't order a new one this one is perfect cleaned up. Removed one cyl. head and was surprised at the size of the pistons and valves. While I did not remove the valves to mag seats I did wire brush between the valves and see nothing to concern. The bores on that side show no cyl. wall wear and the hone marks are still faintly visible well up the walls. I noticed the flat top pistons and a slight chamfer and look to be .050 down the bore. I have been looking at aftermarket rods and pistons for this job. Scat offers floated rods with ARP and come 8 to a set. My plan is to buy a set machine them for the correct side clearance and notch for V6 bearing tangs. Searching around KB offers a 318 floated pistop flat top with valve reliefs which is listed wit .050 more pin to deck height. The valve reliefs hold 5 CCs so some math will be required to figure the best way to come up with 10 to 1 CR over the current 9 to 1 CR. While the core was a std tranny unit the flywheel is not with it. If some one has a 3.9 flywheel to sell or trade please let me know. I have ordered a new ring gear so gear condition not a big deal. Looking forward to getting this project done, I take lots of pictures. I can text them to a phone. I have not figured how to post them here yet. If someone want to post them for me I'll be glad to share. Steve

If any use, I cut my heads 30 thousandths. Obtained a 58 cc chamber and then used Felpro 1008 gaskets which I doubt they make for the 3.9. All in, 9.5 cr from 9.1.
Static and dynamic are gonna to be different so it depends how much overlap you're new cam has. Can't be much.
Cut the head, use the 10 to 1 pistons at zero deck and with the squished gasket, you could come close.

 

[CooperTune]

I have ordered a set of pistons that should put me right where I want to be. There seems to be a common approach to zero deck the piston to deck. Use a .039 compressed gasket giving a correct quench of just under .040. Figure in the 5 CC s for valve reliefs and a 52 CC head and 10 to 1 may be closer than expected. Steve

 

[arrow]

I have ordered a set of pistons that should put me right where I want to be. There seems to be a common approach to zero deck the piston to deck. Use a .039 compressed gasket giving a correct quench of just under .040. Figure in the 5 CC s for valve reliefs and a 52 CC head and 10 to 1 may be closer than expected. Steve

Sounds like a fun v6.

 

[CooperTune]

Having gone back and read this from the beginning I'm wondering if I should start a new thread about how I plan to go about this. I'm still needing a 3.9 5 speed flywheel. Thanks Steve

 

[CooperTune]

Well I found a flywheel and it along with a new ring gear and 12 inch clutch kit are on the way. My pistons are out for delivery 5 days after promised. Yes, I will start a new engine build thread once I have it all. I think somewhere along the way it was mentioned that this would be silly money. That was a under statement. Working for others it is best to know total cost up front. I quit counting at $4000. but have not quit spending. That's about twice the cost of a remaned long block. That does not include a complete ( every part ) cooling system. SS headers, 3 inch exhaust system all the way back and improved TB. Keg mods, aftermarket camshaft, higher compression pistons, ported heads and the list goes on. Steve

 

[arrow]

ok. If you insist on "keg mods" even though every known test on these has proved this fruitless.
If you're going with a single 3" exhaust, go with a complete "straight through" muffler.
With a "baffle type" muffler, you could lose horse power.
Try and use a legitimate "y" pipe and not one that just "butts" into the other exit tube.
Your cam should be on a 110 lsa if you have a choice.

You obviously are not doing this simply for "more power".
It is the challenge of making something out of that which others have been more practical or even "disdainful" in their advice.
"Challenge" is a much more exciting horse to ride than "practicality."
.

 

[RalphP]

ok. If you insist on "keg mods" even though every known test on these has proved this fruitless.

ACTUALLY it depends on which "kegger mod" you're talking about.

See Marty's work at Kegger VRP - UTAWESOME PERFORMANCE sometimes.

RwP

 

[CooperTune]

Thank you both for you interest and input. Please understand just because I don't always take advice does not mean I don't consider it and see how it fits for me, A little back ground may help. I bought this 03, extended cab, SXT with a 3.9 V6 and five speed. Having never owned a V 8 or automatic for my personal use, it with timeless styling four wheel disc, big wheels and tires had to give it a shot. It was not hard to spend a couple thousand on brakes, suspension, AC, alternator and drive belt parts. At that point I could not stand the sound a std V6 makes. It sounds like it is sucking, so on went the complete single 3 inch exhaust system. My exhaust guy is third generation and does the NASCAR exhaust school every few years it is made of the correct parts. For a whole year it was great and ran fine. It did not begin to show issues till I started making long high speed trips pulling 2000 lbs. The first one went fine no codes no issues. I had learned a few things about the ride. Just a wild guess but I feel it's at least 20 HP short of what I need. Just running up and down 95 even small hills are an issue in O/D 5th. Having never heard a V6 in lugging distress it scared the crap out of me. I though the engine was coming apart. OK, no towing in 5 th gear. Even in 4 th it's a little short of power. Many have suggested more rear gear which would move things up the RPM scale. With something in the 175,000 miles on the OD the engine could use a freshening up. The cost of a std rebuild using stock parts with no effort to improve is big money. So I'm spending a few more dollars looking for something that may not be there. We have a local shop that holds an open Dyno day a couple of times a year. Once done I may give it a go. As for the Keg issue I believe there is something to be had there. If not HP it may be something that supports other power adders. Again, thanks and I'm about ready to start. If I had someone to text pictures to that would post them to a thread as I add text it could be interesting to some. Steve

 

[arrow]

ACTUALLY it depends on which "kegger mod" you're talking about.

See Marty's work at Kegger VRP - UTAWESOME PERFORMANCE sometimes.

RwP

Most people didn't go through the trouble Marty went through with his plate design. They simply cut the runners down and all of these tests proved fruitless.
Marty'sdesign increased air velocity and that was what really made the difference.
I always stated there was more to intakes than total cfm output.
At any rate, you are correct. It does depend on what mods you're talking about.