Jackson's 4.0 Stroker build

[Jack15379]

Hi all! I wanted to start a build thread for the 4.0 stroker build that I've started to get input and advice as I'm going along. I'm learning as I go and it would make me feel a lot more comfortable if people with more experience looked through what I'm doin. My intended use for the truck is a dd, something with more power and just to make it really really cool. So getting into it....

 

Starting with a 1989 MJ with a tired 4.0 with a blown head gasket and high oil pressure. 5 speed to a ford 8.8 in back. The motor is completely ready to come out at the moment, gonna pull it in a few days.

 

Right now I'm thinking ill do away with the whole old motor completely and get a HO head and an NVH block (plenty of XJs in nearby junkyards to look through). HO head over edlebrock because of the price. For the stroker part of it I'm gonna do the 4.2L crank and rod swap. I'm aware that ill need dished pistons with a different pin height for this setup. Probably gonna bore it to 30 or 40 over. Gonna need my engineering school friends to help me with compression ratio maths lol. 

 

Valvetrain/airflow: I'm gonna have my head ported and MAYBE do some LS valves to let it breathe, and a cam to make it breathe. I'm trying to learn as much as I can about cams but that sh*t is sooo confusing so any advise on resources to help pick a cam would be much appreciated. Ill do hydraulic lifters with the little oil hole in them and roller rockers. Port matched HO intake with a bigger throttle body and 1 inch spacer under the TB. 24# injectors. 

 

As for wiring and electrics I think I'm leaning towards replacing the whole Renix harness with the HO harness instead of getting my current wiring to work. If I'm gonna put this much into the performance of my motor I want the best wiring I can to use all its available potential. Something I am curious about is whether I should stick with the distributor or go with the coils from the early 2000s XJs, any input on this would be greatly appreciated. 

 

Other miscellaneous things:

-high flow water pump with high flow thermostat and housing

-high flow oil pump with a oil warmer/cooler box from Hesco

 

 

Other things I'm thinking about:

-could I get any more performance with a custom intake manifold or is the stock HO intake that's been port matched pretty optimal?

-electric vacuum pump to tidy things up in the engine bay and not have to worry about low pressure at idle?

-is a cold air intake a good idea or is that stupid?

-oil catch can?

 

Ill be posting more updates as I figure more stuff out and progress in the build. 

 

IMG_0239.HEIC IMG_0241.HEIC

[ghetdjc320]

17 minutes ago, Jack15379 said:

Hi all! I wanted to start a build thread for the 4.0 stroker build that I've started to get input and advice as I'm going along. I'm learning as I go and it would make me feel a lot more comfortable if people with more experience looked through what I'm doin. My intended use for the truck is a dd, something with more power and just to make it really really cool. So getting into it....

 

Starting with a 1989 MJ with a tired 4.0 with a blown head gasket and high oil pressure. 5 speed to a ford 8.8 in back. The motor is completely ready to come out at the moment, gonna pull it in a few days.

 

Right now I'm thinking ill do away with the whole old motor completely and get a HO head and an NVH block (plenty of XJs in nearby junkyards to look through).
 

Your renix block is also a good candidate for a stroker build as it has a higher nickel content than the HO blocks. The NVH revisions are decent also but since you already have a renix block it may be worth keeping.

 

HO head over edlebrock because of the price. 

Just make sure to factor in the cost of machining and valvetrain. Once this is all calculated the difference between the Edelbrock aluminum head and a reworked HO head becomes less. 

 

For the stroker part of it I'm gonna do the 4.2L crank and rod swap. I'm aware that ill need dished pistons with a different pin height for this setup. Probably gonna bore it to 30 or 40 over. Gonna need my engineering school friends to help me with compression ratio maths lol. 
 

The 4.2 rods are short and result in a pretty low comp ratio. The geometry of a short rod engine also is not very good as the rod angle becomes more severe on the stroke (not good for higher rpm). Use the 4.2 crank (preferably from a 87-90 YJ since you won’t have to mache the snout or add a spacer) along with a set of 4.0 rods. There are now multiple piston options that have the correct wrist pin height to fit this combo. Dishing the piston is really just used to drop compression ratios. 
 

 

17 minutes ago, Jack15379 said:

 

Valvetrain/airflow: I'm gonna have my head ported and MAYBE do some LS valves to let it breathe, and a cam to make it breathe. I'm trying to learn as much as I can about cams but that sh*t is sooo confusing so any advise on resources to help pick a cam would be much appreciated.

 

Porting work on an iron head is handful. Also porting work will only be noticeable in the upper rpm band. The more the engine flows over stock the more that power band shifts higher. Gasket matching and cleaning up the casting and maybe the short side radius will keep things tidy. 

 

Ill do hydraulic lifters with the little oil hole in them and roller rockers. Port matched HO intake with a bigger throttle body and 1 inch spacer under the TB. 24# injectors. 
 

 

Hylift Johnson lifters. No TB spacer. And make sure those 24lb injectors are rated 24lbs at 39psi and not 3 bar (43.5psi)
 

 

17 minutes ago, Jack15379 said:

 

As for wiring and electrics I think I'm leaning towards replacing the whole Renix harness with the HO harness instead of getting my current wiring to work. If I'm gonna put this much into the performance of my motor I want the best wiring I can to use all its available potential. Something I am curious about is whether I should stick with the distributor or go with the coils from the early 2000s XJs, any input on this would be greatly appreciated. 
 

Check into stand alone efi. I can explain more later. Think Holley terminator X or HP.

 

Other miscellaneous things:

-high flow water pump with high flow thermostat and housing

-high flow oil pump with a oil warmer/cooler box from Hesco

Scrap the high flow water pump idea. The high flow thermostat is a gimmick. High flow oil pump is harder on your cam drive gear. 

 

Other things I'm thinking about:

-could I get any more performance with a custom intake manifold or is the stock HO intake that's been port matched pretty optimal?

 

99+ intake is the best flowing

 

 

17 minutes ago, Jack15379 said:

-electric vacuum pump to tidy things up in the engine bay and not have to worry about low pressure at idle?

electric vacuum pump pulls a lot of amps. Think hydroboost or stay conservative with the cam specs for good vacuum 

17 minutes ago, Jack15379 said:

-is a cold air intake a good idea or is that stupid?

-oil catch can?

Oil catch not needed. Cai, the thor cowl intake works the best. 

 

17 minutes ago, Jack15379 said:

Ill be posting more updates as I figure more stuff out and progress in the build. 

 

IMG_0239.HEIC 3.08 MB · 0 downloads IMG_0241.HEIC 2.02 MB · 1 download

 

[ghetdjc320]

Replies posted in the quotes above. I’ll try to edit them to make them stand out better

[Limeyjeeper]

2 hours ago, Jack15379 said:

Hi all! I wanted to start a build thread for the 4.0 stroker build that I've started to get input and advice as I'm going along. I'm learning as I go and it would make me feel a lot more comfortable if people with more experience looked through what I'm doin. My intended use for the truck is a dd, something with more power and just to make it really really cool. So getting into it....

 

Starting with a 1989 MJ with a tired 4.0 with a blown head gasket and high oil pressure. 5 speed to a ford 8.8 in back. The motor is completely ready to come out at the moment, gonna pull it in a few days.

 

Right now I'm thinking ill do away with the whole old motor completely and get a HO head and an NVH block (plenty of XJs in nearby junkyards to look through). HO head over edlebrock because of the price. For the stroker part of it I'm gonna do the 4.2L crank and rod swap. I'm aware that ill need dished pistons with a different pin height for this setup. Probably gonna bore it to 30 or 40 over. Gonna need my engineering school friends to help me with compression ratio maths lol. 

 

Valvetrain/airflow: I'm gonna have my head ported and MAYBE do some LS valves to let it breathe, and a cam to make it breathe. I'm trying to learn as much as I can about cams but that sh*t is sooo confusing so any advise on resources to help pick a cam would be much appreciated. Ill do hydraulic lifters with the little oil hole in them and roller rockers. Port matched HO intake with a bigger throttle body and 1 inch spacer under the TB. 24# injectors. 

 

As for wiring and electrics I think I'm leaning towards replacing the whole Renix harness with the HO harness instead of getting my current wiring to work. If I'm gonna put this much into the performance of my motor I want the best wiring I can to use all its available potential. Something I am curious about is whether I should stick with the distributor or go with the coils from the early 2000s XJs, any input on this would be greatly appreciated. 

 

Other miscellaneous things:

-high flow water pump with high flow thermostat and housing

-high flow oil pump with a oil warmer/cooler box from Hesco

 

 

Other things I'm thinking about:

-could I get any more performance with a custom intake manifold or is the stock HO intake that's been port matched pretty optimal?

-electric vacuum pump to tidy things up in the engine bay and not have to worry about low pressure at idle?

-is a cold air intake a good idea or is that stupid?

-oil catch can?

 

Ill be posting more updates as I figure more stuff out and progress in the build. 

 

IMG_0239.HEIC 3.08 MB · 0 downloads IMG_0241.HEIC 2.02 MB · 1 download

You can get a new head for around $600. Clearwater does great new or reman heads. Stay away from the 331 heads they are prone to cracking. A big valve head will net you around 15hp. Use a mild cam or you will tear up the no 6 lobe (Been there twice). The old Mopar performance cam was the best but very hard to find. Comp ams has a couple of good mild ams depending on your compression ratio. A good stroker with a big valve head, bored to +0060 with a good header and the 99+ intake would be good for around 250-260hp, with a huge amount of torque. You will see a very noticeable difference. Cooling can be a challenge on a stroker, particularly if you tune it lean. High flow water pumps are snake oil, Tried them all. Use twin factory fans and a Novak radiator. Cold air intake just creates a lot of noise and maybe 2hp. Bored out throttle body, maybe 2hp, spacer zero. I would use an HO or even a late model Jeep PCM. I have done 3 strokers. The one I did in a 2001 WJ tuned the best. With ODB2 you can see so much more about what is going on. Distributorless and coil packs are much better. Pretty big commitment on the wiring harness integration.

This site has a wealth of knowledge. Only issue is some of the part no's are not available today.

http://jeep4.0performance.4mg.com/index.html

Also the Jeepstrokers.com forum has some great stuff. If I was doing an off the shelf stroker today I would use Mopar, Newcomer Racing or Golen. However the real go to guy is Russ Pottenger (never used him he wasn't around when I was doing strokers, but has a terrific reputation) Russ has all the math and knows his stuff. He would configure you the perfect setup. Use guys that know. This stuff is easy to get wrong.

[ghetdjc320]

Agree with all the above. A cowl intake is noisy but does offer some noticeable gains. Also, look into stand alone efi. I’ve run Holley efi with great success. 

[SatiricalHen]

When I rebuilt my Comanche engine I used a HO head, 99+ intake and bored TB and it’s done well with the mild comp cam I put in it. The TB spacer is a waste of money and will do nothing. 
 

With my Cherokee stroker I went with the 4.2 crank and 4.0 rods combo and from what I’ve seen/heard that’s now the way to go since there’s so many piston options out there now for that combo.

 

from what I’ve head, the renix system actually does better with modifications and getting the most out of it. The renix system uses a knock sensor so it will advance the timing more aggressively since it can recognize knocking and back the timing off then, a HO doesn’t use a knock sensor so it more conservatively tunes the system to avoid knocking. 
 

high flow oil pumps are known to cause excessive wear on the distributor and cam gear and wear them out prematurely, personally I went with stock flow oil pumps in both my rebuilds and they have more than enough oil pressure. 
 

I personally used stock water pumps and thermostats/thermostat housings on my engine builds and they’ve been fine. 
 

I would stick with the horseshoe intake

I’ve never had an issue with vacuum on either of my engine builds, and friends have never had issues on theirs. 
 

only cold air intake worth doing is a thor/spectra cowl intake. The filter laying in the engine bay is much worse than a stock air box, I personally kept stock air boxes both. 
 

I have no experience with catch cans so I can’t comment on that.

 

all of this is just what I’ve heard/seen and personal preference so take it how you want

[ghetdjc320]

Just a note in the HO FI system. Contrary to popular belief, it is completely tuneable. It can be socketed with a flashable eprom and setup for pretty much anything. There are several people who offer the service or you can diy. For Jeep specific tubing of the sbec2 controller (91-95 HO Jeeps) Reach out to Chris at christuned.

[Limeyjeeper]

On 3/29/2021 at 5:51 AM, ghetdjc320 said:

Just a note in the HO FI system. Contrary to popular belief, it is completely tuneable. It can be socketed with a flashable eprom and setup for pretty much anything. There are several people who offer the service or you can diy. For Jeep specific tubing of the sbec2 controller (91-95 HO Jeeps) Reach out to Chris at christuned.

Good to know!!

[EvilMJ]

Everyone above has valid points - I've been researching for my own projects.  I'll try to post up some additional info later - at work right now. 

 

The Spectra is VERY noisy - I'm not too fond of it.  It does flow well.  I'm also not too fond of the assembly of it - I have had a clamp come loose/move once before and allowed an air gap to draw in engine bay air. 

[Jack15379]

The old engine is out and dissembled! I found a surprise, my exhaust has a magnaflow cat and a flowmaster muffler lol.

IMG_0251.HEICIMG_0247.HEIC

 

On 3/28/2021 at 6:12 AM, ghetdjc320 said:

since you already have a renix block it may be worth keeping.

The block is in good condition so ill be reusing it. All the rods looked good too so ill try and reuse those too. To those that have built strokers with the 258 crank: what piston compression height did you use? What compression ratio did you end up with? Any recommendations on pistons? If I can figure out what CR I should shoot for then I can find pistons to achieve that. After looking up articles I'm thinking I'm gonna go with a set of hypereutectics. I wanna keep it on 87 octane. 

 

On 3/29/2021 at 5:51 AM, ghetdjc320 said:

Just a note in the HO FI system. Contrary to popular belief, it is completely tuneable. It can be socketed with a flashable eprom and setup for pretty much anything

Do you know if the 99+ engine management systems with the coil on plugs are as tunable? 

 

 

Gonna be trying to find a junkyard HO head that's in good shape. If I can't find one the Edlebrck it is. 

[omega_rugal]

On 3/29/2021 at 4:51 AM, ghetdjc320 said:

Just a note in the HO FI system. Contrary to popular belief, it is completely tuneable. It can be socketed with a flashable eprom and setup for pretty much anything.

 

not much people have acces to an eeprom flasher and/or the software to edit it...

[ghetdjc320]

40 minutes ago, omega_rugal said:

 

not much people have acces to an eeprom flasher and/or the software to edit it...

This is done daily on the sbec series controllers from Chrysler. They’ve been doing it for years now. I posted the link to the Jeep specific tuner but there are many others. There are entire forums dedicated to reprogramming the sbec units. 

[ghetdjc320]

7 hours ago, Jack15379 said:

The old engine is out and dissembled! I found a surprise, my exhaust has a magnaflow cat and a flowmaster muffler lol.

IMG_0251.HEIC 2.56 MB · 0 downloads IMG_0247.HEIC 2.94 MB · 0 downloads

 

The block is in good condition so ill be reusing it. All the rods looked good too so ill try and reuse those too. To those that have built strokers with the 258 crank: what piston compression height did you use? What compression ratio did you end up with? Any recommendations on pistons? If I can figure out what CR I should shoot for then I can find pistons to achieve that. After looking up articles I'm thinking I'm gonna go with a set of hypereutectics. I wanna keep it on 87 octane. 

 

Do you know if the 99+ engine management systems with the coil on plugs are as tunable? 

 

 

Gonna be trying to find a junkyard HO head that's in good shape. If I can't find one the Edlebrck it is. 

The 97+ JTEC units can be tuned with HP Tuners. 
 

As to pistons, I used the Keith black forged back in the day but there are now several manufacturers making the pistons with the correct pin height for the 4.0 rods. Lookup the calculator on Jeep strokers site for your comp ratio. I run about 10.5:1 with a .038 quench. The tight quench allows me to run regular gas with no pinging. The aluminum head also helps as the combustion chamber design is less prone to hot spots. Newer engines with direct injection can run significantly higher CR and still run pump gas also. 

[omega_rugal]

18 hours ago, ghetdjc320 said:

This is done daily on the sbec series controllers from Chrysler. They’ve been doing it for years now. I posted the link to the Jeep specific tuner but there are many others. There are entire forums dedicated to reprogramming the sbec units. 

 

i wish i had that hardware

[ghetdjc320]

On 4/4/2021 at 1:17 AM, omega_rugal said:

 

i wish i had that hardware

There is nothing super special about an eprom programmer. There are at least 4-5 different latches available for that eprom. Turbo Mopar is a good site for running the sbec ecu’s. The epoxy sealant is the biggest mess. 

[ghetdjc320]

On 4/4/2021 at 1:17 AM, omega_rugal said:

 

i wish i had that hardware

Here are some basic overviews of the process. The first is from 08 and some of the info is out of date:

https://boostedmopar.com/forums/showthread.php?206-FAQ-ECM-tuning-reprogramming-and-how-to-use-D-CAL

 

More recent Jeep specific info: https://nc4x4.com/forum/threads/jeep-sbec-pcm-tuning-91-95.177279/page-2

 

 

[omega_rugal]

interesting reading, thanks

[Jack15379]

On 3/28/2021 at 6:12 AM, ghetdjc320 said:

Hylift Johnson lifters.

Which lifters did you use from them/do you have a part #. When I called them they said they didn't have any specifically built for the 4.0. 

[ghetdjc320]

15 hours ago, Jack15379 said:

Which lifters did you use from them/do you have a part #. When I called them they said they didn't have any specifically built for the 4.0. 

I’ve ordered 3 sets from them. I always get the “S” versions. Let me check the catalog

[ghetdjc320]

16 hours ago, Jack15379 said:

Which lifters did you use from them/do you have a part #. When I called them they said they didn't have any specifically built for the 4.0. 

Part number A-2011 (S). There are 3 versions of this lifter available I believe. It might be listed as an AMC V8 application but that’s the one for the 4.0

 

http://toplineauto.com/wp-content/uploads/2019/04/Lifter-Application-Catalog.pdf

[Jack15379]

Block just went off to the machine shop! 

 

Most of my engine parts have arrived. I contacted Russ and he worked with me to put together a kit of everything I need and answered any questions I had. Phenomenal working with him and his prices are great as well. 

- Russ's custom RaceTech .060 over Edelbrock head specific forged aluminum pistons

- Russ's custom Scat 6.125" floating pin rods

- Russ's custom cam from Comp Cams

- Hylift Johnson lifters

- Edelbrock Head

- Rollmaster double roller timing set

- Hastings ring set

- Russ's custom 1:6.5 Harland Sharp roller rockers

Ill also be using 3/8 push rods over the stock 5/16. 

 

So stoked to get the block back and start assembling

 

@ghetdjc320 You mentioned you've used Holley EFI. Can you elaborate on the process of converting to it and if there was anything you needed to change? Specifically will the OEM sensors work or is there a lot of conversion and finagling to be done. Did you go with a Terminator? 

 

 

[ghetdjc320]

I’ll post a more detailed reply later but the terminator x is a great way to go. And use the hyperspark distributor for the 258. That gives you full timing control and sequenced batch injection (1/5,3/4,2/6) 

 

The hyperspark has a built in crank sensor for timing. You’ll need the Holley CTS and IAT. Bosch 4.9 O2 comes with it. 
 

you can also run an obd1 sbec computer and have Chris @christuned socket and program it. He is the Russ Pottenger of ecu tuning for the 4.0

[ghetdjc320]

The terminator has a built in map sensor (1 bar) and will need to be mounted in the cab somewhere since it’s not fully sealed. You will also need to make sure you have the exact numbers from your fuel injectors to enter the specs in the software. It is self tuning so it should run without further tuning but have Chris dial it in for you. Anything Holley efi I recommend efisystemspro.com

They are super helpful and can get you what you need. You can upgrade to the Holley HP efi but will only gain full sequential injection (every so slightly more efficient at idle) and a fully potted ecu. It can run NTK oxygen sensors and has more capabilities for power adders like turbo and superchargers down the road though. 

[Jack15379]

I just got my block back from the machine shop and I found a hole right above the cam journals at the top of the timing cover area. Ive read that a lot of people have these holes and that it should be perfectly ok. Can anybody confirm this? 

IMG_0419.HEIC IMG_0420.HEIC

[cruiser54]

Normal, even though it looks rather primitive.