whoo hooo! Stroker time!

[Gil BullyKatz]

Blocks are cheap....If I ever blow my .060 overbore, I'll find another at stock or .030 and take it to the machine shop...
As for the difference between .030 and .060, it may seem like no big deal but I consider 25 to 50 extra horsies and 40 to 75 extra pounds torque to be worth it...
measurements are relative to what you expect from them...examples

33" vs 35" tires

5" vs 7" lift

38A vs 38C

.38 vs .357

There are a lot of .060 overbores out there, hi mileage ones too! As for overheating I took care of that with my 3 row GDI a few years back, and the stroker's getting an upgraded water pump during the build anyway. Might do a pair of LeBaron hood vents just in case... I say go for it...

But then again, why think outside the box, I mean, engineers would never design anything with room for improvement, right? They always get it right the first time right?

 

[hjeepxj]

Blocks are cheap....If I ever blow my .060 overbore, I'll find another at stock or .030 and take it to the machine shop...
As for the difference between .030 and .060, it may seem like no big deal but I consider 25 to 50 extra horsies and 40 to 75 extra pounds torque to be worth it...
measurements are relative to what you expect from them...examples

33" vs 35" tires

5" vs 7" lift

38A vs 38C

.38 vs .357

There are a lot of .060 overbores out there, hi mileage ones too! As for overheating I took care of that with my 3 row GDI a few years back, and the stroker's getting an upgraded water pump during the build anyway. Might do a pair of LeBaron hood vents just in case... I say go for it...

But then again, why think outside the box, I mean, engineers would never design anything with room for improvement, right? They always get it right the first time right?

You wont gain 1hp for going w/a .060 overbore over a .030. (let alone 25... )

 

[CRASH]

As for the difference between .030 and .060, it may seem like no big deal but I consider 25 to 50 extra horsies and 40 to 75 extra pounds torque to be worth it...

Are you telling me that the difference between 4.6 (.020" overbore) and 4.7 liters (.060" overbore) is 25 to 50 Hp and 40 to 75 ft lbs?

HOLY COW! By these calculations, going from 4.0 to 4.6 is going to give me between 350 and 440 HP and 460 to 670 ft lbs.

This is great news, I was not anticipating these kinds of gains from my stroker, but then again, I'm no stroker expert, like you guys.

CRASH

 

[hjeepxj]

Are you telling me that the difference between 4.6 (.020" overbore) and 4.7 liters (.060" overbore) is 25 to 50 Hp and 40 to 75 ft lbs?

HOLY COW! By these calculations, going from 4.0 to 4.6 is going to give me between 350 and 440 HP and 460 to 670 ft lbs.

This is great news, I was not anticipating these kinds of gains from my stroker, but then again, I'm no stroker expert, like you guys.

CRASH

:roflmao:

I cant tell if your being sarcastic or not.

Over boring doesnt give hp.

 

[REDXJ4FUN]

Ive seen 4.0s w/a 4" stroke.

Yeah, thats about a .130 overbore.




Id go with .030 just so if I ever decided to rehaul my motor AGAIN, I could easily do it.

since when is a 4in stroke = to a .130 overbore
I'm sure you meant 4"bore just giving you a hard time

 

[JeepFreak21]

Ive seen 4.0s w/a 4" stroke.

Yeah, thats about a .130 overbore.




Id go with .030 just so if I ever decided to rehaul my motor AGAIN, I could easily do it.

Stroke has nothing to do with bore, it's just another way to gain displacement, and there's no way in hell you could bore a 4.0 straight 6 to .130 over! If the cylindar walls even existed afterwards, they'd be paper thin.
Billy

 

[Gary E]

They do use some 4 in pistons in the extreme Hipo amc stuff, but thats after they sleeve the block.

Stroke has nothing to do with bore, it's just another way to gain displacement, and there's no way in hell you could bore a 4.0 straight 6 to .130 over! If the cylindar walls even existed afterwards, they'd be paper thin.
Billy

 

[JeepFreak21]

They do use some 4 in pistons in the extreme Hipo amc stuff, but thats after they sleeve the block.

With a sleeve I see how it's possible, but is 4" .130 over?

 

[Gil BullyKatz]

You're right...I'm wrong...There is no way that more displacement= more hp/torque
I wonder why my buddy on his gsxr 600 could not keep up with my gsxr 750...It's ONLY 150 cc's....
It's not just displacement I agree...or else Snarly Davidson 1200's would blow by me all the time...All things being equal, intake,exhaust,fuel delivery,weight,engine speed,compression,A/F ratios,timing,etc etc etc; Which would dyno more? 4.7 or 4.5?
in MY case the differences between my 4.7 and most 4.6/4.5 strokers is due to use of the custom pistons/4.0 rods versus shorter 4.2 rods used with off the shelf pistons w/dishing...

...course this is just conjecture on my behalf since I did not do my stroker research/homework for months, speak to engine builders, have a reputable machine shop do the critical work and don't have the engine a few feet away...

My advice...Do your OWN research, talk to those that HAVE built strokers, make many phone calls or e-mails, use dyno software and then make your OWN decisions... Everything else, including my drivel is just an OPINION. And you know what they say about having opinions...........

Gil "I need a dyno printout real bad" Bullycatz

 

[hjeepxj]

yeah yeah smartasses, I meant 4" BORE

 

[Gary E]

You're right...I'm wrong...There is no way that more displacement= more hp/torque
I wonder why my buddy on his gsxr 600 could not keep up with my gsxr 750...It's ONLY 150 cc's....
It's not just displacement I agree...or else Snarly Davidson 1200's would blow by me all the time...All things being equal, intake,exhaust,fuel delivery,weight,engine speed,compression,A/F ratios,timing,etc etc etc; Which would dyno more? 4.7 or 4.5?
in MY case the differences between my 4.7 and most 4.6/4.5 strokers is due to use of the custom pistons/4.0 rods versus shorter 4.2 rods used with off the shelf pistons w/dishing...

...course this is just conjecture on my behalf since I did not do my stroker research/homework for months, speak to engine builders, have a reputable machine shop do the critical work and don't have the engine a few feet away...

My advice...Do your OWN research, talk to those that HAVE built strokers, make many phone calls or e-mails, use dyno software and then make your OWN decisions... Everything else, including my drivel is just an OPINION. And you know what they say about having opinions...........

Gil "I need a dyno printout real bad" Bullycatz

I get tired of all this 4.5 is stock bore, 4.6 is .030 over and 4.7 is .060, its not even close, what is it really, a 4.5 to 4.52 to a 4.55?

The point they are trying to make is a slight overbore makes very little diffrence in power output, but can make a big diffrence in reliability.

 

[Bones]

F*CK,
This is getting out of hand. You will not get an extra 50 HP out of a 4.7 vs. a 4.6. The long rod version stroker with a .030 bore is nearly dead on 4.6L. The 4.7L .060 bore is more like 4.66L or so. When I built my stroker, I talked with Mike at Accurate a lot. Mike talked me into going 4.6 over 4.7. He said at BEST I might see "a few" HP difference and that it was not worth it to go the extra bore unless it took that much to clean up the cylinders. He said going .030 still left one more rebuild in the block (at .060) if needed in the future. According to the 4.0 builders I have dealt with, a .030 bore isn't much on the 4.0 and the .060 is easily doable. I have heard of 4.0 blocks going .090 to .100 over, but only after sonic checking AND a realization that it is not going to be a long lived motor.

We aren't building race motors. I can't see why anyone puts so much f'n emphasis on the HP stats. Are you ever going to use all the HP the 4.0 can put out in the rock- let alone the HP of a stroker? H*ll build for low end torque and enjoy the feeling of being able to pull long hills in overdrive and having a more controllable power range when wheeling.

So I can smoke a S10 Extreme with my 33's and 6.5" lifted XJ, it's not what I built it for. I built it to pull low in the RPM range. That is where the long rod stroker shines, and there isn't going to be a noticeable difference in the extra .06L. I have enough power to twist main shafts at part throttle now, what the h*ll is any more power going to do for me?

Bones :skull1:

 

[jammerjamesharmon]

What about COOLING??

I want a stroker eventually when it is time for a rebuild, but it appears to me that cooling could be a big problem. More HP = More heat........ I live in Texas and it gets HOT here. My cooling system is new and in perfect order and is BARLY able to cool my stock engine when wheeling slow with the air on. Please give thoughts and experience on this matter.

:wierd: :wierd: :wierd: :wierd: :wierd: :wierd:

james

http://www.geocities.com/jammerjamesharmon/

 

[Phil]

How much shipped to 95616? Is it available in chrome?

 

[xj-grin]

I want a stroker eventually when it is time for a rebuild, but it appears to me that cooling could be a big problem. More HP = More heat........ I live in Texas and it gets HOT here. My cooling system is new and in perfect order and is BARLY able to cool my stock engine when wheeling slow with the air on. Please give thoughts and experience on this matter.

:wierd: :wierd: :wierd: :wierd: :wierd: :wierd:

james

http://www.geocities.com/jammerjamesharmon/

In my experience, heat isn't a problem. I'm running an accurate power 4.6, with a 180* t-stat and have yet to see it heat up over 200. I think in part, because with all the additional torque/power, I use a lot less skinny pedal, and a lot less strain on the engine on long grades and the like... just my 2 cents.

 

[afjeep2082]

Great thanks for the info guys, uh I also would like to know what all machining and cleaning I will need to get done....sorry my first time dealing with something like this.

 

[Bones]

I want a stroker eventually when it is time for a rebuild, but it appears to me that cooling could be a big problem. More HP = More heat........ I live in Texas and it gets HOT here. My cooling system is new and in perfect order and is BARLY able to cool my stock engine when wheeling slow with the air on. Please give thoughts and experience on this matter.

Cooling CAN be a problem with any 4.0 block. The higher power of the Stroker makes more heat and will accentuate any overheating problem you have had if not addressed.

The first thing to do is upgrade the radiator. I do not think the 3-core GDI is a reliable upgrade. The workmanship is suspect and the tubes are small and prone to obstruction. Some are even occluded from the factory. The 2-core Modine is a much better choice for not much more coin. One can also go the custom route. Though I have been leery of the longevity of Aluminum rads in the XJ, I think the custom route offers the best way to solve overheating if needed (most often the Modine will work).

I really do not think the lower temp T-stats do a thing for improved cooling. If the rest of the cooling system isn't up to par, any temp t-stat will be full open as the engine boils over. I do think that a higher flow t-stat and t-stat housing will allow improved cooling flow to get more out of the radiator upgrade.

I am not sold on the high flow water pumps for low speed driving. I have not had a good experience with the FlowKooler, though others have. I won't say the FK didn't work ok for me initially, but I'm not sure it was worth the extra $ at the time. It failed within two years (actually at barely over one year) and the lifetime warranty was not honored. They gave the, "can't do it if you don't have a receipt" rule. I could buy the reason if it was a one or two year warranty, but is seems sort of silly to need a receipt if it is a LIFETIME warranty. I would not ever buy another one. I now run the HESCO overpriced CNC high flow pump. I don't know if its improvements justify the cost either, but I bought it at the time I built my Stroker. If it fails I'll drop in a stock one and see if it works before I'll spend that kind of $$ at HESCO again.

Another upgrade is to go to the later model swept blade Aux fan design if your XJ has the older straight blade designed one. The new style moves more CFM than its predecessor does.

Decreasing under hood temperatures will reduce overheating problems as well. Getting cool air to the intake, wrapping the header, and installing hood vents help decrease the underhood temps.

It is also good to wire up a relay system to control the aux fan from in the cab. I have mine set up to run off the stock factory control, with the ignition, and without the ignition. I also set it up with a relay control and larger wire direct fed from the battery for less of a volt drop. The original feed to the fan was like a 20 or 22 ga wire, it now runs on 12ga. I do not know how much it really helped, but it sounds like it moves more air now.

All of these mods/upgrades are good to do, stock or stroker, but most seem to become requirements with the stroker.


Bones :skull1:

 

[Bones]

Great thanks for the info guys, uh I also would like to know what all machining and cleaning I will need to get done....sorry my first time dealing with something like this.

My advice is: if you don't have the experience with stock builds, don't try to build your own stroker by yourself. Get with someone who can help you with the tech stuff. If you want straight answers and reasonable prices talk with Mike at Accurate Power. I'm not saying he is always the cheapest, but his stuff will work together and his knowledge and help will save more money in the end.

You will need to find a reputable engine builder in your area. Mike can set you up with the milling specs for the engine you desire to build, but it comes down to a good builder being able to do the work to put together a reliable mill. Do not go on price or appearance of the builders facilities as an indication of the ability of that builder. Check with local race/high performance people and go with their recommendations. Heed this tip well, or you can end up with problems (I’ve BTDT )

You will need to have the block and head fully cleaned, especially the cooling and oil passages. The machining will vary based on what you want to build into the stroker. Boring, and decking are common, as is some milling/surfacing of the head. If you want oversized valves, guides and seats will have to be modified, as will the spring seats. The ports can be opened up some, but the 4.0 head flows rather well so don't spend too much on porting. Rods should be reconditioned and new bolts installed or Mike can supply weight-matched rods with ARP bolts if you want.

Choose components based on how you drive and not on overall HP numbers. It doesn’t matter if your engine can turn 350HP at 6500RPM, if it can't make power in the RPM range where you normally drive, you'll hate it. Choose the most torque for the most used RPM range and you will be far happier with your new mill and spend less on the “bling” race stuff.

Bones :skull1:

 

[Goatman]

I am seeking the advice to all those who have done or helped build one of these. I am not mechanicly inclined when it comes to engine internals but luckily I have a few buddies who are, and say they will help me build this puppy.

First things first here ( http://jakesracingengines.com/jeep page 2.htm ) are the guys I'm looking at for the 4.7L stroker. Anyone deal with these guys? Nick

Jake's Racing Engines seems to know what they are doing. You shouldn't have a problem dealing with them. I bought a motor built by them, and have talked to them a number of times. They are very familiar with stroking the 4.0L, as well as building other engines.

 

[afjeep2082]

Jake's Racing Engines seems to know what they are doing. You shouldn't have a problem dealing with them. I bought a motor built by them, and have talked to them a number of times. They are very familiar with stroking the 4.0L, as well as building other engines.

Did you buy a built 4.0? if so what all did you have to add to it to complete it? how did it run for you?