stroker conversion

[Çrestfa||en]

Ok I am planning on starting a stroker conversion with my dad some time in the summer when I get a break from classes. I want to get a HO 4.0l block and build on that. Thing is, I have a 90 xj none HO engine. I wanted to know what components from the HO donor vehical I will need to make the swap work well/reliably once the rebuild is done and the new egine goes in. So far I figure at least the ECU but any other thoughts on this would be helpful. Yes I have looked at the stroker page and researched it a lot, but I haven't seen anything on putting the HO into an older jeep and am wondering if the ECU and trasmission computer will have conflicts? This will be my frist time building(or doing much at all to) an engine and am gunna use it as a learning experiance.

 

[Eagle]

You're going the wrong way.

The transmission controller is independent of the engine controller, so that's not a problem. However, strokers have a problem with overly-high compression and pre-ignition ("knock" or "ping). The non-HO ECU is better for this because it has a knock sensor to detect ping and retard the timing, thus helping to preserve your expensive new engine. The '91 and newer HO ECU does not use a knock sensor.

The whole point of a stroker is increased torque. A long stroke engine is not and should not be used as a high RPM racing engine. Stroke yields low-end torque. As a starting point, the HO 4.0L produced only 5 more foot-pounds of torque than the first non-HO. By the time you get through building the stroker, you'll have that minor differenece completely eclipsed.

 

[Bender]

I'd agree with Eagle.

If you are dead set on a more efficient head and intake you can retrofit the HO head and intake on your older non-HO block. You'll have to research this topic and there should be plenty. If you're going that far you might also consider using the HO throttle body and adapting the non-HO sensors to mount to it.

In the end a stroker will give you huge torque in the 800-4000 rpm band where large intake flow numbers are nearly as important as those high rpm motors. With this in mind it may be more cost effective to stick with the base non-HO motor.

 

[Çrestfa||en]

My only real reason for wanting to use an HO engine was because of the larger throttle body which also gives me the option for the throttle body spacer and ability to bore it out to 60mm(if a stroker needs bigger fuel injectors it will need more air too right?). Not because I was thinking it would give me a significant more hp/torque. I know a stroker conversion is for low end torque I dont understand where you got the idea that I want a high RPM racing engine. I am just looking to get the most bang out of my buck. Thanks for the information regarding the ECU. Looks like I will want to either buy a proformance ECU or use the non-HO one.

 

[Çrestfa||en]

I'd agree with Eagle.

If you are dead set on a more efficient head and intake you can retrofit the HO head and intake on your older non-HO block. You'll have to research this topic and there should be plenty. If you're going that far you might also consider using the HO throttle body and adapting the non-HO sensors to mount to it.

In the end a stroker will give you huge torque in the 800-4000 rpm band where large intake flow numbers are nearly as important as those high rpm motors. With this in mind it may be more cost effective to stick with the base non-HO motor.

Well my whole reason for getting an HO motor is the fact that I will need the current engine in the jeep until the stroker is done. I'm sorry I guess I really didn't make that clear. I'm planning on building it over a few months as I have to work and go to school still. And it is something for me and my dad(he used to build engines) to do. I've tried to avoid asking newb questions but this was one thing I couldn't find anything about but you guys have answered it well, Thanks a lot.

 

[REDXJ4FUN]

like the guys above stated keep te renix system and block. go with a ho head and as late modle intake with a bored out stock HO TB. its not hard to adapt the renix TPS to the newer TB.

 

[Eagle]

The HO block either has the bung for the knock sensor, or has a boss there that you can drill and tap for it. I wasn't saying not to use the newer block, just that the Renix ECU is better suited for duty with a stroker engine.

I guess I assumed you wanted to run high RPMs because you seemed fixated on converting to the HO head and computer, and they don't do much for you except at high RPM.

 

[Çrestfa||en]

OK sounds like I will do what you said RED, use the older block, ECU, and use the HO head and intake system. Really thanks for the info guys it helps a lot there's a lot of good info on the stroker sites but this was just one area I was unsure of, and sorry about sounding sarcastic eagle

I can't waiting to be able to get started on this... maybe I should quit school? .......nah

 

[Dr. Dyno]

The way I see it, building up a HO block in your spare time is the most practical option. I'm in the process of building up a 4.6L stroker based on a '00 block in my spare time while I still have my strong-running 4.0 in my '92 XJ. You can follow my progress on my stroker website:

http://www.angelfire.com/my/fan/stroker.html

You can reuse your Renix computer, wiring harness, and sensors on the HO stroker. You'll need to adapt the Renix TPS to the HO TB (not difficult) and weld a threaded bung onto the driver's side of the HO block for the knock sensor. You'll definitely need oversize injectors (I suggest the Ford 24lb'ers) and you can also make a MAP adjuster (see link in my sig.) to adjust the fuel curve. You will also reuse the Renix fuel rail on the HO intake manifold.
_______________________________________________________________
- 1992 4.0 XJ Laredo UpCountry with modifications - 171k miles - AX15, NP231, D35c, D30
Estimated 240hp@5250rpm/280lbft@3500-4000rpm, 1/[email protected], race weight 3465lb
- Future mods -
4.6L stroker (under construction)
- Websites -
Jeep 4.0 performance, 4.6L stroker build-up
- Tech Webpages -
CTS resistor trick, Dual electric fans, IAT sensor relocation, Intake manifold heatshield, MAP adjuster, Oil temp. gauge install
- Info Pages -
Automotive formulae, Jeep 4.0 cam specs, Jeep engine dyno graphs

 

[Çrestfa||en]

Thanks dyno, I think once I start this project it will give me an intimate knowledge of my inline6 which is great cause I wana treat her good

 

[CW]

I built mine with an 87 block and a 94 head, manifolds, and TB. The only thing that isn't bolt on is the TPS and that took me an hour and a half to take care of. I port and polished the head and the stroker revs faster than my 4.0 ever did. My engine makes rediculous torque with the 250h cam, but I was warned not to take it past 4900 rpms by both AP and my machine shop. I can take it right up to 4900 and it is still pulling strong. I am using the HO fuel rail also, you just have to re-route the fuel lines, and it gives you the option of an adjustable fpr. With the 24lb injectors I am running rich, so be prepared to either make an ajustable MAP or buy an adjustable regulator.

 

[Çrestfa||en]

I built mine with an 87 block and a 94 head, manifolds, and TB. The only thing that isn't bolt on is the TPS and that took me an hour and a half to take care of. I port and polished the head and the stroker revs faster than my 4.0 ever did. My engine makes rediculous torque with the 250h cam, but I was warned not to take it past 4900 rpms by both AP and my machine shop. I can take it right up to 4900 and it is still pulling strong. I am using the HO fuel rail also, you just have to re-route the fuel lines, and it gives you the option of an adjustable fpr. With the 24lb injectors I am running rich, so be prepared to either make an ajustable MAP or buy an adjustable regulator.

wow that sounds damn sweet, Deffinately a good thread here. thanks for info CW. And yes I am planning to make and ajustable MAP soon, since my major is Electronic engineering it will be worth while in more ways than one

 

[Bender]

Just a note.

I see talk of injectors but not mention of fuel pressures.
Keep in mind the fuel pressure up until 1995 was 39 psi and after it is 49 psi. This will have a significant difference in your injector fuel flow so account for it in your injector sizing.

 

[Çrestfa||en]

ok, thanks.