Renix 4.0 To 4.2 Stroker Questions

[big66440]

I've been planning on building a 4.0 on the side to replace my tired one, but the thought of upgrading to a mini stroker sounds tempting along with a bored TB, and some 5.0 injectors,,, how easy or difficult is it to actually accomplish? I would stick with the factory 89 renix block, head and injection set up are there any pitfalls or things to look out for? I'm mechanically inclined and except for the machining I would do the work.

[Stacks]

Here's a site with lots of useful into about strokers.  There are several others also.  Using the RENIX head and intake greatly chokes the gains from a stroker.  I am sure others here will pop in and add more about this.  The new Keith Black pistons available are a real boon in bulding a 4.0 stroker... no need for a different crank and rods!!  Hope this helps a bit.

 

Larry

 

 

Edit:.... Ooops... forgot the link.  http://www.jeep4.0performance.4mg.com/

 

Space Cadet Syndrome getting worse!!  lol

[cruiser54]

You'll be fine. Stock size injectors but with 4 holes will probably work, too.

www.strokedjeep.com has the TBs for less than $100 exchange.

[92tanMJ]

I was looking at doing on those

http://www.jeepstrokers.com/forum/viewtopic.php?f=15&t=3083&start=15

 

This site will have a lot of helpful info for ya

[ftpiercecracker1]

Why would you do a 4.2 instead of a 4.6? If i remember right a 232 crank is needed for the "mini" stroker. I know a 258 crank is what makes the big boy stroker. :brows:   If your gonna do it why not go all the way? Get you a 258 crank and rods and run some new 4.0 pistons. Done. Not really but that covers the mechancial essentials.

[big66440]

You're right the 4.7 sounds much better, you guys think it will make a big difference in gas mileage?

[cruiser54]

You're right the 4.7 sounds much better, you guys think it will make a big difference in gas mileage?

I've heard it's as good as stock fuel mileage wise.

[92tanMJ]

Oh Ive heard the gas mileage is worse that stock. Maybe its because youve got all of those extra horses to feed and the people driving and reporting back like to let them sing. I don't know. But I do know that why people go with 4.2s and stuff is because one theyre a lot cheaper to make. I think if I remember correctly if you do good 4.7 I think youre looking at least 2000 to do it? don't quote me on that thats just the number I can remember. But like they always say there is no replacement for displacement.

[dasbulliwagen]

Anyone have any more info or a link to the mentioned Keith Black pistons?

[HOrnbrod]

Here's a site with lots of useful into about strokers.  There are several others also.  Using the RENIX head and intake greatly chokes the gains from a stroker.  I am sure others here will pop in and add more about this.  The new Keith Black pistons available are a real boon in bulding a 4.0 stroker... no need for a different crank and rods!!  Hope this helps a bit.

 

Larry

 

I believe Larry is referring to the Keith Black KB-944 piston family. These "new" pistons (came out in 2008 IIRC) make it possible to use the 4.0 rods and still keep the piston head below the head deck plane for proper quench w/o detonation. Before these you had to use the 4.2 rods, do a lot of machining, or a combination of both to get the correct quench. You still need the 4.2 crank for a stroker.

 

http://www.summitracing.com/parts/uem-kb944-030

[big66440]

Oh Ive heard the gas mileage is worse that stock. Maybe its because youve got all of those extra horses to feed and the people driving and reporting back like to let them sing.

 

 

:???: :dunno: :ack: I'm sorry I don't get it

[Alexia]

The 4.2 crankshaft is what makes it the stroker in the first place.

 

To make a 4.5 stroker use a 4.2 crankshaft and the shorter 4.2 connecting rods. If you want to go higher than that there are many options available. The Keith Black IC944 pistons allow the longer 4.0 connecting rods to be used since they have a higher wrist pin height.

 

Mini-strokers are cheap to build. To go past that it requires a $500 minimum investment in either Keith Black pistons or a combination of other parts to get it correct.

 

Gas mileage will be dependent on how the new setup is tuned.

[92tanMJ]

Oh Ive heard the gas mileage is worse that stock. Maybe its because youve got all of those extra horses to feed and the people driving and reporting back like to let them sing.

 

 

:???: :dunno: :ack: I'm sorry I don't get it

 

extra horses = more horsepower (or torque) , feed = gas, letting them sing =  exhaust make different 'sounds'  lol

[Stacks]

Oops... again.... Hornbrod is right... still need the 4.2 crank.  I need to stop making posts when I'm in 'Night Owl' mode!!!!  :doh:

 

 An observation/analogy about the stroker mileage.  It may not be as bad as it might seem.  My old '67 'Cuda, 273 2bbl, 4 speed got 14-14.5mpg in stock form. After a rebuild, .030" over bore, 10.5:1 pistons, 284/300 duration .500/.510 lift cam, headers, Mallory dual point, 3 angle valve job etc. Driving the same roads it got 19-19.5mpg.  If I stayed out of S.E.G. mode the mileage stayed right about there.  Granted the 'Cuda's engine wasn't stroked so the changes weren't as drastic but a 4.0 stroker might surprise us on mileage.  Just guessing of sourse!!  ;0)

 

Larry

[HOrnbrod]

My mileage stayed roughly the same overall. Went down from 16MPG to 14MPG in town (mainly due to heavy right foot syndrome), yet highway went up from up 18MPG to nearly 21MPG. I was pleasantly surprised by that.

[ftpiercecracker1]

Um, no, a 4.2 crank with 4.2 connecting rods will net you a minimum of .5 more liters. If you want more than that, than you can get the head ported, polished, block bored .060 over and/or if you have REALLY deep pockets get your 4.2 crank offset ground. It is possible to to turn a 4.0l into a 5.0, but that is $money$.   The typical jeep stroker is around 4.5 4.6 liters. Just as an FYI, my stroker would have cost me $2,400 total, out the door, running in my truck, no short cuts, machine, parts, doodads, everthing. I was $300 short and the rest is history. . . :cry:  

 

I will admit i know nothing about the mini stroker stuff, but i would like to think i know a thing or two about the bigger stroker.

 

 

if you want to know the facts about strokers these two sites have more information than you will ever need.

 

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

http://www.jeepstrokers.com/forum/

[Alexia]

I believe I have around $2,500 into my 4.7L stroker which includes all supporting changes such as bigger throttle body, 1999+ intake manifold, injectors, and some other items.

 

A bare long block from Golen is $3,800.

Hesco bare long blocks start at $4,795 and they do not even indicate what is included in that price.

 

A simple 4.5L stroker can be really cheap if the crankshaft and connecting rods can be found for a good price. Get used crankshafts cleaned and polished then install new journal bearings all over.

[Biotex]

I've been storing a 4.2 complete engine just for a future stroker build. It is a 79 model engine, so it should have the heavy weighted crank. One of these days...

[ftpiercecracker1]

I've been storing a 4.2 complete engine just for a future stroker build. It is a 79 model engine, so it should have the heavy weighted crank. One of these days...

 

 

How bout today? :yes:

[HOrnbrod]

Hesco bare long blocks start at $4,795 and they do not even indicate what is included in that price.

Glad I got mine back in 05. The 4.6L with your choice of cam and other options was about $2800 back then. I wouldn't even consider one it now for nearly $5K. Yet they are still selling them nearly as fast as they can build them all over the world. Should tell you something about their reputation and reliability.