I honestly do not know. Not much above stock. It is basically an upgraded cam and bearings. My decision was just piece of mind that I had a rebuilt engine for now while I had it out.
Where did you get your stroker engine from?
- Thread starter Chris
- Start date
Brianj5600
TJ Expert
I am thinking with some attention to detail with a 4.7L on 87 octane, I can make similar TQ and HP to 6psi on a stock motor. I am also not sure how healthy my engine is. It sounds like it may have a broken skirt on cylinder 1. I would not feel comfortable adding boost with out going into the engine.
OP
Thats true. Not to mention that with stock internals you can only run a certain psi before you’ll run into issues anyways.
Brianj5600
TJ Expert
From the calculator on Jeep strokers your CR will be 8.6 and dynamic CR will be 7.35. That will cost efficiency and power. You might consider having the block decked or even have the pistons .010" out of the cylinder with that head gasket. That would give you a CR of 9.2 and dynamic CR 7.83 and .041 quench. The consensus for 87 octane is 9.5 CR and 8.0 dynamic.
Wow, Thank you. I understand 1/2 of what you said but I am smart enough to let my rebuilder know. Thanks again.
downthepines
TJ Enthusiast
In theory, A sweet spot will exist. I feel like a 50-75 hp gain while doing a rebuilt is the ticket. This thread is very interesting. Thanks to all for sharing your info/experience.
I bought a Golen about 2 or 3 years ago. It cost about $6000 and $2000 to install. It's my daily driver so about 23K miles. The only issue I have with it is, it had so much power that when I took it off road on my dana 35 with 35" tires blew out!!!! LOL, forced me to get a 44 now I am installing the pump for the rear lockers......
The Golen makes those 35's feel like riding on the original 30's my jeep came with. I can cruse at 85 mph all day long on freeway.
If the ability to break a Dana 35 is the metric by which we judge the need for more power, none of us would have more than a 4 banger.
There is lot more to it than just CR as I'm sure you know though. Decking the block would have the benefit of having tighter quench height (squish) which will allow for lower octane and/or more timing. Combustion chamber design, piston design, and cylinder head material also matter a bunch.
At 180K miles and a pesky lifter tick, I have to start to think about options. My rig is a DD, so it would be nice to find a middle ground stroker. 50 HP gain would be fine with me as long as I can maintain factory-ish reliability. I'm ok running 91 octane if that is what it needs.
A couple things I keep seeing are worth pointing out......
One is that peak hp numbers aren't the main thing to look at when talking about strokers in our jeeps. Putting your foot down with big tires at 1.5k rpm and it walking up the hill vs having up downshift is where it's at. Ignore the idiots like me who try to bang gears and abuse Hondas. That is fun though. 3.07's on 32's with my very modified 4.0 was terrible both on and off road. With the stroker, on the road it was fine. Great even. It still sucked trying to crawl in 4 low though. Stroking instead of proper gearing is a half assed bandaid unless it's a mall crawler only.
Also, there is no "psi limit" on any motor. PSI is an almost useless number to use to compare things unless it's exactly the same setup down to same engine, cam, head flow, blower, etc. On literally the same motor, 10 psi from one turbo/supercharger is completely different and unrelated to 10 psi from a different turbo/supercharger. There is no such thing as "this motor will blow a head gasket at X psi" unless you are using for example a car that came stock from the factory with a turbo and you are making broad statements about relatively stock engines with stock turbos and just turning up the boost. And even then, it's only a general guidline and not so much the increased psi that is doing it as much as the heat causing preignition dramatically increasing cylinder pressures.
One is that peak hp numbers aren't the main thing to look at when talking about strokers in our jeeps. Putting your foot down with big tires at 1.5k rpm and it walking up the hill vs having up downshift is where it's at. Ignore the idiots like me who try to bang gears and abuse Hondas. That is fun though. 3.07's on 32's with my very modified 4.0 was terrible both on and off road. With the stroker, on the road it was fine. Great even. It still sucked trying to crawl in 4 low though. Stroking instead of proper gearing is a half assed bandaid unless it's a mall crawler only.
Also, there is no "psi limit" on any motor. PSI is an almost useless number to use to compare things unless it's exactly the same setup down to same engine, cam, head flow, blower, etc. On literally the same motor, 10 psi from one turbo/supercharger is completely different and unrelated to 10 psi from a different turbo/supercharger. There is no such thing as "this motor will blow a head gasket at X psi" unless you are using for example a car that came stock from the factory with a turbo and you are making broad statements about relatively stock engines with stock turbos and just turning up the boost. And even then, it's only a general guidline and not so much the increased psi that is doing it as much as the heat causing preignition dramatically increasing cylinder pressures.
I had 140K and a bad head gasket with the wife's DD TJ. I had just done the head gasket on the XJ 2 months prior to the TJ going out and had already talked to Russ. He recommended a rebuild after 120-140k and a ported head wouldn't provide much gain without a mild stroker. I upgraded the injectors and need to get it tuned still after a year, AFE Wide Band is still sitting on the install table. Without the tune the gas mileage improvement has been around 16-18 mpg with 4.1 and 33's. Prior to the rebuild I was down to 12-14 as I have a heavy foot.
In my world, that is about like talking to your gear setter and making him tell you what mine the ore came from that was used to make the gear set. I don't really give a shit.
Here, build me a motor, I've got it geared as low as we can get it, the tires are too big, the transmission sucks, the motor sucks. I can only change one of those and that's the motor so do that and call me when it is ready. Oh, I have to get it through a smog check.
My Jeep is my daily. I had the benefit of knowing my motor was on it's way out well in advance so I could afford to slowly start putting my stroker together while still having something to drive. When the old motor finally gave up the ghost, I had the replacement all but ready to drop in. I highly suggest this route to anybody with s tired motor thinking of doing a stroker. It spreads the cost out over time, gives you something to tinker with, and not being in a rush let's you do things the right way and cheaper in the end I think. Also, it leaves you time to take pictures....
And yes I got blue masking tape to match my gaskets. So what. Don't judge me
And yes I got blue masking tape to match my gaskets. So what. Don't judge me
Again, not trying to be argumentative. I don't understand where you are going with that though. I assume that was pointed at my gearing comment. Are you saying you disagree? I mean, was thrilled with how my Jeep drove down the highway with 3.07's and 32's after the stroker compared to the 4.0. The crawl ratio was unchanged though which hindered picking my way over obstacles in 4 low still. It was just moving too fast still and there was a lot of clutch slipping. More power isn't really going to help that much.
I'm not in disagreement with anything purely because I have zero experience with building a stroker and when I get this one installed and running, that will still be true. That and I solve all the bullshit about crawl ratios in an entirely different manner.
We agree then? Sorry, I'm a couple beers in so maybe a little slow on the uptake. I do think there is no substitute for correct gearing though, but road gearing and gearing for different types of off-road situations will be different for sure. The fact that you have more power plays in to that equation of courses. I would love to have higher gearing (or a sixth gear) for the highway but lower gearing for the trail with my current motor and 4.10's. A Rubi transfer case would be dope and maybe something I'll look at in the future, but priorities.
Brianj5600
TJ Expert
Am I off on 9.5, 8.0 .040" quench and 87 octane? Assuming that all edges are softened on the piston and chamber. And yes there are still more variables.
Let me put it this way. I put a charger on the 04 Unlimited with stock tires, auto, 3.73 gears. It ran very well. I acquired and installed a set of JK 32 factory take-offs in the street tread. I re-geared it shortly after that to 4.88 because I didn't appreciate the power loss.
I have never used the calculator so you could be more spun up on it than I am, but talking to Russ on the phone, he was recommending 9.5-9.8'ish for 93 octane for me with a decent size cam that had a fairly low dynamic CR. This is with his spec'd pistons that have pretty tight quench although I'm not sure the number. Not saying you were wrong at all though. Just speaking more in a general sense for everybody reading I guess. Sorry, like I said, cook out beers got me up on that soap box rambling all kinds of craziness
