so how much power does your stroker have?

[Cjmartz2k]

The chevy pistons would actaully be cheaper if your block would work, but it would require a .125 overbore and that's on the harry edge. You would need to get the block sonic tested first, and then still I would worry about how thin the cylinder walls would be. Not the best option in my opinion.

As for my experience, I've only driven mine (TJ w/5 speed, 3.07's, and 31's) for one weekend after it already had about 500 miles on it, and it it was effortless cruising about 80 on the freeway with a headwind. No way I could have done that before, and I had about every bolt on/cam/tuning possible done to my old 4.0. I didn't get to race it or anything, but I was VERY happy with the highway habbits. I can't wait to get back and take it to the track and grenade a few rear axles :cheers:

 

[stever6kid]

Look if you guys used forged pistons it will not be a budget stroker. Go to www.summitracing.com and type in speed pro. They are hyperutectic pistons an go for about 25-30 dollars apeice. Much cheaper than forged pistons and they have sizes to fit stock, 0.030, and 0.060 bores on the XJ.

 

[philip_g]

The chevy pistons would actaully be cheaper if your block would work, but it would require a .125 overbore and that's on the harry edge. You would need to get the block sonic tested first, and then still I would worry about how thin the cylinder walls would be. Not the best option in my opinion.

I don't remember the specifics but I trust this machinst, he does work for about every dealer in town.

He had a dodge V10 crank in there that spun some bearings, interesting crank. Spendy too.

 

[philip_g]

Look if you guys used forged pistons it will not be a budget stroker. Go to www.summitracing.com and type in speed pro. They are hyperutectic pistons an go for about 25-30 dollars apeice. Much cheaper than forged pistons and they have sizes to fit stock, 0.030, and 0.060 bores on the XJ.

thanks, cheap pistons have eluded me. I see no need to go forged either.

BTW 21.39... is the price today.

 

[JJacobs]

Terry at Western Engine in Denver Colorado is doing my build since I currently dont have a garage. He tells me with intake down pipe header and exhaust I can expect anywhere from 275-305 hp and more tork than necessary for any rock crawler.

He's blowing smoke up your a$$, I bet it makes no more than 180 rwhp on an actual dyno (remember those things, they don't work on theory but fact?)
I've still never seen a printout from a real live dyno where a stroker makes more than 200 at the wheels. That'd be 230 wheel to get your 300 flywheel, so we keep it apples to apples.

 

[Quacked]

Those speed pro pistons wont work on a stroker.

THe reason for forged pistons is the relocated pins.

The wrist pin has to be moved more towards the skirt to keep compression under control.

I would say there are not enough of us wanting to make these big motors to justify the tooling expense for a manufacturer to offer a line of cast pistons.

 

[tealcherokee]

Those speed pro pistons wont work on a stroker.

THe reason for forged pistons is the relocated pins.

The wrist pin has to be moved more towards the skirt to keep compression under control.

I would say there are not enough of us wanting to make these big motors to justify the tooling expense for a manufacturer to offer a line of cast pistons.

or you're wrong, and you should go away.

the speed pro pistonswork fine, and a stroker can be built from 8:1 to 11:1 compression

 

[Blue XJ]

Those speed pro pistons wont work on a stroker.

THe reason for forged pistons is the relocated pins.

The wrist pin has to be moved more towards the skirt to keep compression under control.

I would say there are not enough of us wanting to make these big motors to justify the tooling expense for a manufacturer to offer a line of cast pistons.

They worked fine in my motor so far, its got about 4500 miles on it.

 

[philip_g]

They worked fine in my motor so far, its got about 4500 miles on it.

they're also all over the stroker yahoo group so I see no reason why they shouldn't work.

 

[philip_g]

He's blowing smoke up your a$$, I bet it makes no more than 180 rwhp on an actual dyno (remember those things, they don't work on theory but fact?)
I've still never seen a printout from a real live dyno where a stroker makes more than 200 at the wheels. That'd be 230 wheel to get your 300 flywheel, so we keep it apples to apples.

I'll be pleased with 200.
I'll have real dyno results after mine is in but I'm too cheap to do a before dyno

 

[Quacked]

Oops, I meant the pin needs to move towards the head of the piston.

While I am a pro mechanic I have not assembled a 4.7 stroker yet.

My experience with strokers has been relegated to a 1/4 inch and a 1/2 inch stroker flatheads in a pair of retro rods (not that black primer junk either), and a half dozen 2.3 welded cheater motors for a neighborhood dirt modified.

(I have also built several destroked 360 mopars to fit a 350 inch rule class.)

In both cases the incresed stroke caused the piston to protrude past the engine deck. The fix for this is either custom connecting rods that are shorter.

I was looking at one companies stroker kits on their website, and it showed pics of rods and pistons. I geuss I figured that either the piston or the rods were custom length.

I am really excited to be able to build a 4.7 this summer. My 4.0 is showing its 190,000 mile age and use fluids. It needs so much work that I am just building a motor.

 

[philip_g]

you understand that people run the 4.2 con rods with the strokers right? Hence I'm assuming no more height problem.

 

[tealcherokee]

Oops, I meant the pin needs to move towards the head of the piston.

While I am a pro mechanic I have not assembled a 4.7 stroker yet.

My experience with strokers has been relegated to a 1/4 inch and a 1/2 inch stroker flatheads in a pair of retro rods (not that black primer junk either), and a half dozen 2.3 welded cheater motors for a neighborhood dirt modified.

(I have also built several destroked 360 mopars to fit a 350 inch rule class.)

In both cases the incresed stroke caused the piston to protrude past the engine deck. The fix for this is either custom connecting rods that are shorter.

I was looking at one companies stroker kits on their website, and it showed pics of rods and pistons. I geuss I figured that either the piston or the rods were custom length.

I am really excited to be able to build a 4.7 this summer. My 4.0 is showing its 190,000 mile age and use fluids. It needs so much work that I am just building a motor.

no shit..... longer stroke, and the piston goes up higher.....

theres more than 1 way to change that...... as just said, shorter rods

 

[PapaPump]

He's blowing smoke up your a$$, I bet it makes no more than 180 rwhp on an actual dyno (remember those things, they don't work on theory but fact?)
I've still never seen a printout from a real live dyno where a stroker makes more than 200 at the wheels. That'd be 230 wheel to get your 300 flywheel, so we keep it apples to apples.

funny thing is...dynos do work on theory! have you ever looked into the development of the dyno industry? the methods used and the numbers that are spit out are all based on some arbitrary crap. they started up using drums of a size and weight that was simply enough to make the engine work hard. then they use computer programs to spit out a number that sounds about right! it's nothing like the way the OEMs test the crankshaft horsepower, but it is a good method to test for real life power gains from modifications. the big problem is that no 2 dynos spit out the same numbers all of the time for the same car. there are other factors such as temperature, fuel, etc. that change these numbers, but the fact is that dynos are just tuned to spit out relative numbers...not necessarily accurate numbers

 

[BlueCuda]

I would love to have built mine with the longer 4.0 rod and a custom piston but I was in a hurry. I blew my shit up and had to get it back together quick so I built a budget motor. I am not a big fan of the power band it has, its very peaky and doesn't really take off until 3000 or a little above. As mentioed before I think the longer rod would help broden the power band and make a better smoother and more powerful combo. But at a much higher cost.

 

[jeepinwi]

I am thinking of a stroker too but i was told that it improves milage cause i m getting 15mpg mixed HO AW4 stock tyres so i need someone to tell if my mpg is going to get any better than 15 mpg

I'm currently on my 3rd tank of gas in my stroker. I've been doing 90% highway cruising. My first tank got me 17.2 mpg, and my 2nd tank got me 19.75 mpg. I'll expect over 20 mpg from this current tank. It getting me about 1 mpg less than the 4.0 got me.

 

[JJacobs]

funny thing is...dynos do work on theory! have you ever looked into the development of the dyno industry?

Uh, no. The rollers accelerate quicker, it's making more power. Not hard to grasp. I leave the figures and formulas to engineers and those extracting power numbers from thin air....

 

[PapaPump]

it was hard to grasp though for the engineers that had to turn the feedback from those rollers into believeable and repeatable numbers...it isn't just straightforward. 1/4 mile times are probably a better gauge with a consisent driver

 

[JJacobs]

1/4 mile ET mostly reflects torque, launch quality, shifting and so on. The HP is reflected in the MPH.

 

[BLSXJ]

my stroker made more then enough power, wheich lead me to the conclusion

"there is no such thing as to much power, just not enough traction"