ZR6 390 Engine - Wide Open Throttle Discussion

[Paxdad]

Interesting how in your original post you were cautioned about WOT sustained operation and the ill effects of such. Now fast forward to this post and your exploit to further experiment with WOT operation certainly leads me to conclude you know nothing of a marine inboard engine. It's your boat so run it how you want but when you one day hear a really hard metal to metal bang and you have a significant amount of some milky looking slugs in your bilge let us know. On a side suggestion and as pointed out previously marine inboards have windage trays in the oil pan to facilitate the return of oil to the oil pump and to contend with oil flowing in different directions. When you operate at max rpm for sustained periods the lower portion of the motor runs out of oil and fails to lubricate the crank/ rod components which increases operating temps. So when a cautious buyer wants to have ECM data pulled and he sees excessive rpm operating hours at 5000 rpm they are likely going to walk away. I know I would.


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[Team230]

Thanks for all the feedback.

I think a couple of you took my comments/discussion the wrong way. I was simply asking for other's experiences with this. I fully recognize the limits of my boat and engine...even more now that you all shared your knowledge and experience. This being said, I'm still "allowed" to be bummed about those limits and imagine a world those limits don't exist.


Thanks.

[Paxdad]

Bummed is better than being stumped by the realities of prolonged WOT operation. I do agree with you though on the limitations of an inboard wakeboard motor. Look at it this way you bought a tractor not a salt flats rat rod.


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[TylerDWilson]

Team 230. There is some validity to some of these posts/replies, but also a lot of old school nonsense. Everyone is correct in the sense that these are purpose driven boats built for a specific reason, and that reason is to tow and not go fast. From your post however, it doesn't sound like you are looking for a go fast boat, you are just looking to run at a speed that the boat is able to do.
First off, which I can't believe that nobody on here led with this, they all just tore into you, read your PCM owners manual. It gives you recommended operating specs, and seeing as you are new to boating and especially to inboards/Vdrives, it would be good to read the entire manual to familiarize yourself with the way the engines were built and designed to run.
There is nothing wrong with running these boats at high speeds, myself and my friends do it all the time as we are primarily wake boarders but like to do a fair amount of barefooting. What you need to be looking at is your your RPMs while at WOT. PCM installs governors on all of their engines so they cannot over Rev. And whoever was talking about redline on here is an idiot, look at the Tac, there is no redline on it becuase the PCM governor won't allow these motors to get close to their "red line". Now, the manual clearly states that in order to get the best performance and maximum life out of your motor, you should actually be running near the top but just under WOT. The recommended WOT for your motor is 4800-5300 RPM, the preferred operating RPM is 5200RPM. Your range of WOT RPMs can be adjusted by changing your prop. You should basically be able to run your boat at WOT all day long, assuming you are never surpassing 5200RPM with no issue at all. That RPM in a 230 should have you around the 40mph mark. I have the 343 (WOT range is 4600-5000RPM with the preferred being 4800RPMs) in my 230 and I have set it up to where 23.5mph (wakeboard speed) with fully loaded ballast (3500lbs) and crew, I am running 4300RPM. At WOT with basically no load, and completely empty, I am running 37.8mph at 4800RPM. When barefooting, I drop the throttle all the way and just let the boat run as hard as it can; if we want to get from one side of the lake to the other, I drop the throttle and let my engine run as hard as it can: 4800RPMs, because that's what PCM designed it to do and recommends for best performance. I can run that speed and RPM for hours on end and every gauge I have sits perfectly still, no fluctuation whatsoever. All this to say, you should not be getting an engine temp rise at WOT, assuming you are not surpassing 5300rpms. I recommend you peg the boat and see where you're RPMs are, and if it's running anything over 5200RPMs, then buy a prop that will allow WOT to sit at 5200. Don't feel bad about running your engine hard, it's what PCM designed these things to do. As long as you don't exceed spec, keep up with standard maintenance, and keep all of your fluids right, that engine will run smooth and reliably for a very long time.

[Tom_H]

Yes, you should prop the boat to hit the recommended RPM for WOT. However, if you would have kept reading your manual, you would have also found that PCM's recommended max cruising RPM, depending on engine, is generally around 3800-4000 (in the specifications section). They also go on to say that prolonged operation at high RPM's (WOT) will shorten the life of your motor, and they also recommend leaving the engine on for 3-5 minutes after prolonged operation at high RPMs to allow the engine to cool down. These are just marinized truck engines. They were never intended or designed to be operated at WOT for extended periods of time. Would you run your car at 4-5000 rpms for extended periods?

[Paxdad]

TylerD,
Your engine cannot run all day long at Wot 5300 rpm. Let's just say your all day is 12 hours on the lake. You know why? 12hours x 5gph=60gallons (29 gallon tank) therefore you would be out of fuel far before your statement holds any any fact. However, I am sure some of us here on the planet that would like to see you prove us wrong.
The original post that started this topic was sustained WOT for something like a 45 minute period.


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[DaveNH]

TylerD, calling the suggestions/opinions people gave "old school nonsense" is pretty foolish. You contradict yourself, first you say it's all nonsense and OK to run all day at WOT, then you say to read the PCM manual. It's the manual that says not to do what you are saying everyone should be able to do.

Team230, you got a lot of excellent advice in this thread. I liked the analogy that running a boat at WOT is a lot like running a car/truck up a hill towing a trailer in a gear that keeps you at WOT. Lots of load, high rpm, brutal on the engine. In your couple of posts you didn't mention your WOT rpm, which is pretty central to this discussion. I'll add that there are a lot of engine/boat specific limitations. My GT-40 in a direct drive ski boat can run in the mid 4000's pretty continuously, cruising at 40-ish mph, I've never seen a problem with engine temp or loss of oil pressure. I have it propped to 5,100 at WOT so I do no more than short bursts, I'm above the recommended max of 4,800. My boat puts much less load on the engine than a 230. In a heavy wake hull there just isn't a good answer for high speed cruising, it's a trade-off that you need to live with, but then again cruising at 32-34 mph in an amazingly comfortable boat is not the worst thing in the world!

[Team230]

I appreciate all the feedback here. I think my Wide Open Throttle topic should have read, High RPMs for sustained period of time. WOT is a bit silly...I get that. I was really just on Norris Lake and instead of doing water sports all day like I typically do, I needed to get from point A to point B and there was a big distance between the two (it's a big lake). I was constantly monitoring my Engine Temp which made the run more stressful than necessary...so I thought I would ask opinions.

I know I came to the right place...opinions are plentiful here!

Thanks all!

[jkallen21]

That guide and a whole lot more come from here: https://www.planetnautique.com/vb5/f...uals-brochures

FYI - back to the beginning of your post, the oil senders in the ZR6 are not that good in my experience. I went through 3 of them before getting one that worked reliably. You pushing WOT might have been the catalyst, but it was likely going to fail soon anyway.

[Scooter G]

Whoa, 5 years of peace on the Planet, and it breathes again...

[srock]

Yea this post/issue has been addressed by increasing the price of fuel.