reliable tow stroker cam

[titan]

I've been spending hours every night this week learning stuff. I'm sure a stroker build be built in a fraction of the time I've spent reading. Just when I think I figure I know what I need to optimize for I learn I need to care about another variable and my previous "best" choice is a bad choice.

I have a 95 ZJ on 33s with stock gears that had to go down to first through the mountains last summer when fully loaded towing a tent trailer so I'm looking into a stroker for more towing power. I am not willing to sacrifice idle (running http://www.autofab.com/grand_cherokee_v8.htm now!), fuel economy, reliability, and don't want to troubleshoot any issues down the road. I don't want to do anything that will confuse the electronics, which is why I was asking about putting in a comp cam other than the 232 in http://www.jeepstrokers.com/forum/viewt ... =15&t=2928

I'm learning toward 4.6l low buck stoker with its 9.69:1SCR 8.46:1 DCR ,if I've entered everything correctly into the calculator, but with a different cam since the 231 isn't recommend for FI. My stock (270/270, 7.13:1DCR) is also out since the DCR would be too low.

After my research the top contenders for DD/holiday tow rig are late model stock (253/259, 8:1DCR)), comp cams 68-232-4 (250/256, 8.3:1DCR), mopar P4529228D (240/240, 8.64:1DCR)), Lunati 63500 (250/256, 8.41:1DCR)), and Isky 133125 (256/256, 8.26:1DCR)) or 133125/26 (256/262, 8.26:1DCR)). All seem like reasonable choices. I'll share some of my research to show I'm trying to figure this stuff out instead of just asking for solutions.

At a high level the Lunati 63500 with new springs looks best, but http://www.jeepstrokers.com/forum/viewt ... 7&start=15 makes me nervous.

They said the surfaces on the Lunati were way out of spec for surface roughness/Ra. The journals measured over 30ra and that was even on the rearmost journal that had minimal bearing wear. Clevite says they recommend a 10ra or less for cam journal finish to provide reliable bearing service life with 15ra being the upper limit. So, they polished my Lunati cam and measured a 4ra on the journal surfaces

I don't want to have to do extra work on the cam when it shows up. I'd be more interested in the Lunati if there were more threads about how long their engine has lasted since installing one. It feels like it is awesome on paper to get somebody inexperienced to buy it, but has short comings that somebody experienced would recognize. Am I paranoid?

The 232 seems acceptable, even though it hurts performance below 1800rpm and then do well http://www.jpmagazine.com/techarticles/ ... to_16.html, except for one post;http://www.jeepstrokers.com/forum/viewt ... 2&start=15

My original stroker with the crap cam got 17 miles to the gallon in my TJ 4.56 gears and 33" tires NV3550 HWY.
The Comp 69-232-4 everything else the same I am getting 11-12.5:(

I don't want to lose that much fuel economy!

Could the P4529228D even be used in the 4.6l low buck stoker with the higher CR? It's only 0.18:1 higher DCR than the suggested cam. I don't mind running a bit higher octane since a local chain sells ethanol blended gas of a couple octane higher than the major chains. If you can get a higher octane fuel you might as well take advantage of it and go for a high CR, right?

What would people recommend for me? I'm very eager to get to the point I understand the tradeoffs of what I'm putting in my vehicle.

[SilverXJ]

I've ran the comp cam 231 on my 2000 and it didn't exhibit idle issues. It played well with the EFI.

You mention ethanol. How much of a blend are we talking about? You would probably lose power going with a gas with high ethanol concentration in an engine not designed for it. Yoru fuel system may not be able to handle the ethanol either. Not to mention its just a crap fuel source.

[titan]

It turns out they don't offer 10% ethanol anymore! My province recently mandated 5% average so that chain dropped their special extra octane ethanol blends and are just another vendor of the same fuel as everybody else. So I'll be running regular 87 octane fuel that happens to have 5% ethanol. :/ BTW I'm not totally opposed to 91, but I'd definitely prefer to save money by buying cheaper gas.

I think I should get more of an RV cam than the 231 for towing I'd like to do, even if it works well for most people. Wouldn't one of the cams I suggested offer better fuel economy and torque at lower rpms?

[SilverXJ]

I would call a few companies and ask for a custom grind. Don't bother calling comp as when I did they weren't too interested in doing a custom grind and told me just to go with the 231.

[lafrad]

Hmmm... Ethanol is becoming the fuel of choice for race teams, profession and amateur... very few actual negatives in a *combustion engine*... but a discussion for another thread.

In this case, its being used as an octane booster, and up to 15 or 20%, it will be fine to use in our jeeps and strokers... it affects the target AFR only slightly in these concentrations, so your injector change will most likely make up for it.


For a tow cam, I would stick with the "smaller" off the shelf cams, or the "bigger" stock cams. going with a mopar sourced cam will most likely give you the wide lobes and factory lifters, which is a good thing for reliability. it will be REALLY strong on torque, sacrificing a bit of power above 4500-5000 rpm... just remember where it will be spending most of its time. Port the head well and it should make things MUCH NICER.

[titan]

I don't plan on spending much time at 4500 Highway speed will be 1800/2500 rpm in 3rd/4th currently, or 2500/3000rpm once I replace the 3.73s with 4.56s.

It seems like the P4529228D will provide better fuel economy and torque at towing rpm than the 96+ cam, yet with its lift still run with stock springs and be reliable. And has the bonus of piece of mind about the computer. Provided it doesn't set the DCR so high I can't use it instead of the 231.


Not to sidetrack my own thread too much, but Ethanol seems to be a crap replacement for gasoline due to its lower energy content, but not a crap fuel source. A couple years ago Saab showed off a 400hp twin turbo v6 that ran on 100% ethanol! If you're going to use ethanol as a fuel source just make sure you build your engine with a compression ratio well beyond what you can achieve with gasoline. But I get your point - don't just drop ethanol into an engine optimized for gasoline and expect anything more than crap.

[IH 392]

It turns out they don't offer 10% ethanol anymore! My province recently mandated 5%

I wish they'd pull their heads out of their asses around here! good move!

[titan]

I found a comment about the P4529228 "Stage I Purple Shaft" finally! [url]http://www.jeepsunlimited.com/forums/sh ... st4801[url]

...I'm very happy with it, but you'll have to consider that you'll be trading off some low-end power for top horsepower...the difference starting at around 2500rpm is very noticeable

Since I'd like to see more performance from 2000 instead of 2500 it seems like I should look at something else.

Does anybody have experience with the different desktop dyno applications? I feel like I should plot all these cams I'm considering to see how they look.

[JeepFamily]

My son and I are building a 4.6 stroker for his 1997 ZJ and have the machining done but are held up choosing the cam. We aren't as interested in high rpm and would like to protect or improve idle to maybe 4000 + torque. My first thoughts on the guy who ran the 232 and dropped his mileage to 11 was running out of the torque band since the 232 drops off rapidly below 2000 rpm. simply increasing tire size to 33 from stock would reduce his engine rpm to ~1600, well below the stock cam's performance. However changing gearing to 4.56 would bring his rpm back to 2000+. Based on the torque curve this should have been a good thing?? A couple of questions though

1. what is the engine rpm of a TJ with 4.56 gears on 33s? anyone know? What are the highway speed and driving conditions? I'll post him and hopefully get the specifics.
2. The only 232 torque/power curve I've found is for a 4.0l, so how does this translate to the stroker?

In Dino's stroker website, http://www.angelfire.com/my/fan/updates.html , he originally installed a Crane cam CRN-753905 and @ 34000 replaced it with an OEM cam. Sounds like the OEM worked well.

Our ZJ is my son's driver so we are very interested in protecting daily mileage. I like the 232 but I'm very concerned about it's performance below 2000 rpm. Looks like torque is on a very steep decline and I would expect this to be quite noticeable both in practice and mileage. More to come.

[amcinstaller]

welcome to the forums. not to sound rude but you should start your own topic, maybe in the build section about what youre after, a budget and your concerns, and im sure people would love to give you a hand

[JeepFamily]

Thank you for the greeting but I'm a bit confused. Our situation is similar or the same as the thread and I thought I added to it?? anyway thanks for the recommendation.

[SilverXJ]

1. what is the engine rpm of a TJ with 4.56 gears on 33s? anyone know? What are the highway speed and driving conditions? I'll post him and hopefully get the specifics.

http://www.grimmjeeper.com/gears.html is a good gear & RPM calc.

2. The only 232 torque/power curve I've found is for a 4.0l, so how does this translate to the stroker?

The curve is about the same, only more.

[GoMopar440]

Thanks for that link.
Lots of helpful info to be found in there. Looks like I wouldn't pick up too many more RPMs (about 250 @ 75MPH) if I were to swap the 4.10 gears for 4.56's while keeping my 35's. I'll wait and see if a gear swap is still needed after the stroker is in before I go that route though.

And for the OP: It looks like you and I have the same or very similar target goals for our strokers. Maintain a regular fuel friendly compression ratio, and pick up more grunt for low/mid speed acceleration and power (ie: pulling). For my build I'm willing to sacrifice some top end by sticking with the factory cam (using a new Melling replacement) rather than trying my luck with an aftermarket grind cam. New lifters, valve springs (Mopar) and a Cloyes double roller timing set will also be a part of the recipie for the sake of reliability. I probably won't mess with getting new rockers unless the existing ones show signs of wear. Pushrods will have to be measured and ordered though since I'll be zero decking the block.