Need Opinion/Review of Lunati Solid Roller cams

I'd like to get some feedback on a Lunati Solid Roller grind, part number 40230733/60333: 249/255 @ .050, LSA:110, Lift: .585/.600.

Engine Specs: 4.15 stroke RB engine, 4.375 bore, Diamond dish pistons at 10.3 CR, .039 quench, 440EZ MW ported by Hughes with Comp 1.5 rockers, Indy single plane EFI with 90mm TB with Edelbock Elbow, Holley HP EFI with knock sensors, 34* total timing. Using Hi-Tek 1.75" header/manifold, but a custom set of Hi-Tek 2.25" have been ordered and are on their way. Using closed loop cooling, 180* t-stat, CP oil cooler.

I have this mill in a 24ft jet boat, built for the large whitewater in Hells Canyon on the Snake River, formerly powering a Hamilton HJ212 water jet. When building the engine, I had originally considered the Lunati 60333 cam, however on advise of Hamilton, they suggested that the motor be toned down to keep the pump from being overpowered and blowing out (severe cavitation), which the Hamilton was only rated at 350hp. What I ended up with is a Hughes solid roller, 235/241, LSA: 110, Lift: .535/.545. However even with the little mild cam, the Hamilton was still over powered and required a delicate hand on the throttle to avoid blowing out. Out of frustration, I ended up swapping the Hamilton pump for a Scott Jet 912, which is a very capable two stage pump rated up to 1200hp. Now that the pump is up to par, I am considering going back to my original plan and swap to the Lunati 60333, to give a few extra ftlbs in the 4500-5000 rpm. Currently with the mild cam, the Scott loads the engine out at 4500 rpm, which equates to 494hp/577ft lbs. I'd like to bump it to the 630-640 ft lbs to get the WOT revs up around 4800 +/-, like some of the dyno numbers I seen posted with that cam. The motor cruises the boat at 3300 rpm, and low end torque is not a concern since the jet can't utilize it anyway in the lower revs. I am also considering using a lower rate valve spring (200/500) on advice of Lunati, to keep the stresses off the Morel roller lifters, and since the motor will unlikely see anything over 5000 rpm with the new pump; EFI rev limiter set at 6500.

The feedback I'd like to get about the cam is idle quality, tunability with EFI, and longevity (again, using lighter 74620K1 springs). I have this motor's idle set at 900 rpm, with 13" of vacuum...keep in mind this is while turning the jet, which is directly coupled to the engine. I would consider the idle very tame, and would have no problem stepping it up, but I wouldn't want it too raunchy and make it cantankerous. Thanks

With the manifolds it has I would get a custom cam ground in the 112to 114 LSA, that way you can go a little more duration , better Idle & would be a better match to your combo, talk to Dwayne Porter,,, Porter Racing Heads

FYI, the manifolds are actually water jacketed short tube 1.75" headers going into a 3" collector. However, a set of 2.25" with 3.5" collector are on their way. The risers are 18" long, no hint of reversion. Thanks for the feedback, I appreciate it. BTW, these manifolds will be up for sale soon if anyone wants them for a stockish 383/440 marine motor.

I would still talk to Dwayne.

I hate wide separation LSA on any N/A Hi Po type Mopar B/RB motor, why give up low and mid range power with those cams

To answer the question....... as best I can.......
I havent used that Lunati cam, but it looks like a suitable choice for the direction you’re trying to go.
I also agree that for operating range you’re running the motor in, 200/500 springs loads should be plenty.

To put my .02 in on things that weren’t asked.......
for that operating range, I think the MW sized ports and manifold were a mistake....... but you have what you have.
Even at 500”, they’re likely tuned for a higher tq peak than 4800.
(I realize the choices for MPI BB Mopar intakes is pretty limited. Looks like there is a std port EFI Victor though.)

I also feel the 2.25” primary is too big for the operating range you’re targeting.
If you could have whatever you wanted, considering the size of the heads/intake...... I’d have gone with 1.875.

Thanks fast68plymouth for the reply. Funny now that you mention it, Hughes was the one who recommended porting to MW in order to move the TQ up on the dinky cam, so I had him strap them to his CNC machine before shipping them. But after reviewing a couple graphs with the Lunati cam, it appears the porting don't hurt the 4000-5000 rpm TQ, in fact a little higher than say the RPM head graph I looked at...but that could simply be a difference in the dynos and testing conditions.

I thought the 2.25" was too big as well and specified 2" on the order, but the Hi-Tek aussies assured me that the 2.25" will yield the most power due tests they performed with a Mercruiser 496 HO (a mild mannered Chevy based engine), and I gave them the benefit of the doubt since I've learned that marine exhaust systems are much different than a dry system on land, plus they've been building marine headers long before I built this boat. The reason why Hughes specified the dinky cam was due to the short length of dry risers that were originally on the Hi-Tek headers when I purchased them off the shelf at CP Performance, but since then I TIGed on an extra 9" section of jacketed dry-pipe to ensure that water reversion won't drench the O2 sensor. When I talked to Hi-Tek about the dry-pipe I added, they assured me that I can run a much larger cam than I am running now and are incorporating the long riser on the 2.25" custom set. At any rate besides Hi-Tek, I've talked to CMI, Basset, Stainless Marine, Lightning, and a few SMEs such as Alex Haxby @ Haxby Speed and Marine, and they all agreed that the 1.75" headers are holding this motor back, and I'm likely to gain at 4500 with the header being the only swap.

FYI, after the exhaust mixes with the cooling water at the end of the risers, the exhaust goes though 4" Hardin transom tips equipped with salisbury flapper valves. I've also added a pair of 4" stainless Flowmaster 854040 Super 40 Delta Force mufflers, outside the transom to tone down the bark into a mellow tone...and they do so with no negative affect on performance according to the Holley datalog. Most marine mufflers are nothing more than very expensive stainless steel taters shoved into the pipe, which drastically cuts down WOT rpm.

With all the exhaust you have on there, I still say 112 to 114 lsa, if Dwayne says different I would trust Dwayne.

Sounds like you’ve done your homework.

Nothing left to do but swap out the parts and see how it shakes out.

If the wot operation lands at 4800rpm, then you get an “A” for your efforts.

As a comparison...... street 505 with bowl blended RPM heads and a 6bbl....... even that mild combo made 628ft/lbs at 4800....... but peaked at 4300(645ft/lbs).

Better std port heads, single plane manifold, and a roller cam....... should have been able to push the peak up another 300rpm.

I’m not saying you won’t reach your goals for power @4800....... I’m just saying it may not have peaked yet by that rpm.

I'd would say: "I havent used that Lunati cam, but it looks like a suitable choice for the direction you’re trying to go. I also agree that for operating range you’re running the motor in, 200/500 springs loads should be plenty." is a pretty good indication that Dwayne is thinking like I am, using the tighter LSA/duration to target a specific RPM. Granted the 2.25" exhaust seems a lot for 4500 rpm, but I'm left that up to the SMEs of Hi-Tek marine, as their test results seem legit.

I'm hoping to get some feedback with that cam concerning EFI, as LSAs of 112-114 typically works better with the traditional speed density and MAF setups, but the Holley HP system seems to work well with 108-110 LSA cams...my motor purrs nicely from 700-900 with a 13.5 idle target AFR. https://youtu.be/OruBFxQwC6k

BTW, you interested in crafting up a grind? I'm very willing to support businesses of forum contributors.

Interesting combo and it looks like you've been doing your research and made some good choices. I probably would not have gone MW ports for a boat engine but you have them and they aren't hurting you too bad at your size. I suppose if I was going MW port size I would've gone ahead and put a 4.25 stroke in it just to pick up some more inches but once again, you have what you have so now you just need to focus on the tuning.

Dwayne can get you the cam you need. The Lunati would probably work okay but if it was my money I'd just have Dwayne spec a custom roller. Only thing I see that I'd change if it was mine would be to drop the alternator down using a low mount kit just to give you a little more room at the top of the engine. With the mechanical fuel pump out of the way the alternator can drop down.

The block is near the end of its boring life, and I'd probably look more into a 572 setup if I wear this one out. So far, it running really good and lasting really well, considering that marine engines crank out constant power ie: cruising rpm of 3300 requires 200 hp input into the jet. Like I stated earlier, it runs really well and even out spins the LSA and Raptor 575 SC marine engines, but now its time to out spin the new LT4 :p ...naw, I'd like to see it brought up to its potential output as I originally intended as there is power left on the table, which can be handy when climbing up a class 5 rapid while loaded.

One reason why I prefer a N/A motor vs the supercharged motors like the LSA, Raptor, or the Hellcat crate I had considered marinizing, is a N/A motor is much more forgiving especially when it comes to 110* days and sub-par fuel (which happens a lot here in the Northwest). I even had to run on 87 octane in a pinch, however the motor did not hint or even record any ping on the computer datalog, though I tried to be dainty with it until I could give it a shot of 92 and octane boost...the same can't be said of the LSAs that filled up on 87. I opted for the Diamond pistons as they are a near perfect mirror dish of the EZ combustion chamber, which I am sure it bought me a little wiggle room along with the cold air intake, 34* total timing, and 12.5 AFR. However since that day, I keep a case of Torco octane boost in the storage compartment just in case I encounter another marina with sub-par fuel.

We've been building 610/630 Mopar big blocks using TF 240 heads, Trick Flow intake, 10:1 compression and a modest hyd roller cam so that is what I'd build for a boat. The "pro street" type cars get the TF 270 heads with the Indy intake and a solid roller cam and they make around 700 hp and 650 torque. Your engine is a mixture of those parts. Are you using a Dual Sync distributor with the Holley EFI system? Where do you put the O2 sensor when you have a water jacket exhaust? Did you build the EFI system yourself? I see the port injection on the intake but can't tell which ECU you're using.

Yup, purchased a universal Holley HP system from Haxby Speed and Marine, another contributor to a jet boat forum I belong to. I modified a MSD dizzy with mechanical advance locked out, and ground off the other 7 reluctor tabs and left #1 for the cam sync. Spark is triggered off the damper into the Holley HP ECM, which fires a Daytona Sensors CD box. It running dual knock sensors, triggered to retard at engine noise over 80% when running over 2000 rpm, which was advised by Holley EFI for a big block as the mechanical cam is a bit noisy at an idle. However over 2000 rpm, noise settles down to 20-30%. Its runs sequential injection, seems to work really well after playing with the injector end-angle tables. The injectors are 60lb. I did have a Wilson 1287 CFM 4150 4bbl throttle body on it originally, but on advice of a Holley Tech forum member, I swapped to a 90mm monoblade with the Edelbrock 3894 elbow. In the end, it was a very good decision as the cruise throttle AFR was very erratic with the 4150 (13.1-13.9 with a target 13.5), but the monoblade setup evened it out to 13.4-13.6.

Now I see MSD sells a RB/Hemi dual sync dizzy, plug n play with the Holley System. The NTK O2 sensor is located at the top of the manifold, hanging above the starboard valve cover. Hi-Tek can TIG weld it in on request.

Sounds like a Holley (or MSD) dual sync distributor would clean things up a bit for you but not really required since you have the system working.

Yea, grinding all but the #1 tab off and configuring the ECM for hall effect was the Holley Tech's idea back in 2014, which I did suggest to Holley that they add a dual sync RB dizzy into their product line. Look like they obliged, and I may swap it out during the cam change as it would be a cleaner signal than "analog" pulse.

So the goal is to run the the engine at max torque, not horse power? Been around boating and boat racing a little bit, and have not seen this before. But they all had propellers.

Horsepower is nothing more than an equation of torque over a time component, in this case RPM. So Horsepower = (Torque x RPM) / 5252. The key is to build max torque in the RPM where its needed to achieve max horsepower input into the jet. Props can use low end torque to launch skiers, or launch a boat down the Firebird Raceway. However, low end torque means nothing to a jet as it can't use it. You can take a jetboat, tie the transom to a great big tree on the shore, and run it to WOT...and as long as it doesn't cavitate, it will pump water at full power while standing still.

Horsepower requirement of a jet is a non-linear graph, increasing HP demand as the RPM exponent increases as by this equation: Horsepower required = (RPM/1000) *3 x (impeller KW rating) x 1.34. My jet is currently configured as 4.05KW, the 1.34 is a KW to Horsepower conversion constant. So you can see that say at 1000 rpm, my jet requires 5.4hp/28.5ft lbs, at 2000 rpm = 43hp/114ft lbs, at 3000 rpm = 146hp/256ft lbs, at 4000 rpm = 347hp/456ft lbs, at 5000 rpm = 678hp/712ft lbs, at 6000 rpm = 1172hp/1026ft lbs. Since my motor maxes at 4500, it requires 494hp/577ft lb, so increase more RPM input into the jet, more torque is needed in the 4500-5000 rpm, hence the reason why I'd like to stay with a 110* LSA and increase the duration to move the peak TQ up into that area, vs the small cam that I have now.

The jet pump is similar to a dyno, or the stall speed of a converter while on the trans brake.

The WOT rpm is the point where the load and power output are equal.

Is this picture in WA or ID?
It looks like there are a bunch of homes their and a bunch of game trails coming down the hills
I've been to the south end once driving home from ID to see that canyon, I didn't get to see as much of it as I was hoping to We did see a brown bear along the road to it though

The boat was parked on the WA side of the river, near the OR border, about 40 miles up from Lewiston.Those are cabins on the ID side of the river, where the state has been selling off its land to private owners. They are only accessible by jetboat as the road ends at Heller Bar.

So the intent is to run the motor at an rpm that develops max hp.

Since there is a formula to determine how much power is required to turn the pump a given rpm, the goal is to make that amount of power, at wot, at that rpm.

It doesn’t really matter if that’s the engines peak power or not.

As long as the pump load and the engine output are equal at wot, at the desired rpm....... that’s as high as the engine will rev.

so it would seem to me you would want a broad , not so Peaky power curve. 112ish lsa, with an intake in at 108 ish & 255ish @.050 in & ex, .600ish lift, Very mild lobe solid roller.

There is no need for a broad power curve.
The only rpm the engine will operate at during wot is whatever matches the load of the pump.

At wot the engine will always run at one rpm...... no matter how fast or slow the boat is going.

At lower engine speeds, there’s less load....... so having lots of low speed tq does nothing for you.

It’s not like a car where going up a steep grade at 2500 requires more work than going down hill at 2500.

With the jet....... you’re always going up hill....... and it’s always the same “hill”(load) for any given rpm.

Using Marks specs, at 3000rpm the load from the jet equals 146hp/256ft lbs.
It doesn’t matter that you might have 371hp/650ft lbs on tap at that rpm.
You can’t provide any more load to the motor at that rpm than 146/256.
If you apply more throttle at 3000rpm than is required to make 146/256........ the motor just revs higher.
The only way to increase the load is to turn the pump faster.

You keep adding throttle, the rpm keeps going up.....until the motor doesn’t make enough power to gain any additional rpm.

How heavily the boat is loaded, and how fast or slow it’s going has no affect on the engine speed.
The motor will go right to full rpm as soon as you go to wot.

Valid point

Basically, where the engines power curve at wot intersects with the pumps load curve....... that will be the terminal rpm....... which may or may not be where the motor makes peak power.

If a person has the time and money then the engine can be run on a dyno and the power curve overlaid on the pump curve to find the intersection. Then a person would know if the power curve is correct for the pump or not.

Most marine engine manufacturers will provide a dyno graph for their marinized crate engines, which can be overlayed with the pump or propeller power absorption curves, and then change the impeller or prop pitch to best match it up the engine. However most boaters on this river like myself, prefer to run a higher pitch impeller to move the most water through the jet for the best pump performance in class 5 rapids, which requires a powerful big block or a supercharged small block. Now after I swapped out the Hamilton Jet with the more capable Scott 912, which has a very good and broad performance envelope, I can install a "proper" cam to open up the engine's potential to best compliment the jet. Granted this Mopar with its small cam already outspins the LSA, Raptor 575, and comes close to matching the LT4, I would still like to have the extra power in reserve, that is otherwise being left on the table by the small cam.

Jet boat engines are from a very different world than any thing else we build and use , trust ,me on this.
Until you driven a jet boat and a prop driven boat it is hard to imagine the differences
The pump is trying to compress liquids, impossible to do, correct You can turn water into steam trying to do that though, it is called cavitation and very harmful to the pump parts

And don't forget about the sneaker rocks hidden under the water!

I've piloted jet and prop boats & barges of all sizes and vocations, and this is where the diesels have a distinct advantage in both applications...they are built for those long hours of continuous load. Costs of purchase and install, that's a whole other discussion for another forum.

Right, but then you've built the wrong motor if the peak hp is at much higher rpm.

Russ, now think about that for a minute.

You’re targeting 630-640ft/lbs at 4800rpm.

How would you build this BB Mopar motor to achieve that power level at that rpm, and have that be the point of peak hp?

How high would the low end tq have to be, and how sharply would the curve have to be dropping for 4800rpm to be the point of peak hp?

Your targeting 640ft lbs/585hp@4800....... and that’s going to be the highest hp reading.

The cam I would use to reach the target 640ft/lbs@4800, I’d expect to make peak hp north of 6000 with the heads, induction, exhaust the OP’s build has.

But...... it’s irrelevant....... since it will only rev as high as the load of the pump allows.

The other way to look at it is........ if the pump load limits the rpm to 4800......then, with the motor in use in the boat...... that will be the max HP.

Dwayne is 100% correct, I am targeting the engines output to turn at or near 4800 at WOT, as that is the pump's input rpm that equals the max torque output that a typical 4.15" stroke RB block is capable of producing, in naturally aspirated form, and cam the engine for that rpm target. I don't care if the pump won't allow the engine to run at peak HP, as re-configuring the jet for a lower KW rating to achieve that peak, is not the ideal configuration for pushing an 8,000lb boat up through a class 5 rapid...for a 2000 lb Sprint boat on a race course, then go ahead and tune the jet for peak motor HP. But to tune the motor to match the max horsepower rating of this jet, then not many on this forum have such an engine and I would be best saving my money for Mercruiser QC4V or GE T-58 turbine.

Let’s say you could build a motor with a perfectly flat torque curve from 2000-8000rpm, and that the tq value for that entire range was 712ft/lbs.
That’s 712ft lbs/271hp@2000....... and 712ft lbs/1084hp@8000.

Hook it up to the OP’s jet drive....... it’s going to max out at 5000rpm....... which would be 712ft lbs/678hp.

However, virtually any power curve that yielded 712ft lbs/678hp@5000........ would also max out at 5000rpm....... unless the upward trajectory of the power curve of the engine was steeper than that of the jet pump load curve, at the point at where the two curves cross.

Forgive a naive question......

If the engine could produce more torque (at WOT) then the jet required, then the engine could be run
at only part throttle. Is this a correct statement ?

If the "perfect" engine was 500 inches for this application, why could you not use a 600-incher at less throttle opening ?

If the motor made more more TQ than the jet required at its maximum input rating, it would mean that the jet would be operating at an rpm above its rating and outside its performance/efficiency envelope. Such condition was experienced with the Hamilton HJ212, the impeller absorbed the power but the jet yielded zero performance gain...the extra horsepower was wasted in cavitation and impeller reversion.

Sure you can use a 600 cid engine, 6.2 Raptor 575, 6.2 LSA, 6.2 LT4, 6.2 Hellcat, 632 Haxby Chev, etc...none of these engines exceed the 1200hp rating of the Scott 912. Running more cubes would allow more intake vacuum at a given hp, and not need the octane of a supercharged engine. If Scott comes out with more progressive impellers for their 912 jet, I would consider a swap to a 550hp Cummins QSB6.7.

I guess my lack of understanding is more fundamental. Why is it going to max out at 5000? If it's cavitation, wouldn't you put a higher output pump that had a higher operating range? Are gear reductions not used?

Because if the engine cannot produce any more torque than 712ft lbs over 5000 RPM, the jet has effectively "loaded out" the motor at that RPM. If it can produce more than 712ft lbs over 5000 rpm, say 862ft lbs @5500, then the jet will fully load the motor at 5500 rpm.

Oh yea, gear reductions are not desirable...they add weight and move the motor forward, throwing off the boats CG and increasing the chances of stuffing the bow into the "green room": https://youtu.be/BM7eXZeXRJo

With the engine at wot, at whatever rpm that is.............. the output and the load are in a state of stasis.
They are equal. In order for the rpm to change........ something else has to change to allow that to happen.
Either the output or the load.
Since the load curve climbs rather steeply with rpm, in order to raise the rpm from the point of stasis you’ll need to make enough additional power to exceed the rate of change of the load curve.

To lower the rpm, close the throttle some, rpm will drop.

If you closed the throttle say, 1/2 way....... the rpm would drop to the point of the equilibrium between the new 1/2 throttle output and the equivalent pump load.

It’s much the same as the beginning of a dyno pull with a water brake.
Let’s say you want to start the pull at 3000rpm.
You start applying throttle and load together until you get to where you’re at wot, and the engine is steady state at 3000(or just under).
In order for the engine to actually accelerate and make the pull, something has to change, or the engine will just stay at that rpm.
Since you’re already at wot...... you can’t just “make more power”....... so you have to start releasing the load to allow the engine to run at a higher rpm.

With the jet pump, there is no releasing the load........ so if you want the engine/pump to turn faster...... you have to make more power.

To take the analogy a bit further....... once you had the load valve on the dyno set to apply the necessary load to hold the motor at 3000rpm........ you could back the throttle off and the rpm will fall off.
You could keep going to wot over and over again....... but wouldn’t get past 3000rpm because that’s where the power and load are equalized.
So, let’s say that you did that initial load valve setting with the timing 10 degrees less than what’s optimal......... and then you put the correct timing in the motor. Now, that motor makes more power at wot it will go beyond 3000rpm because the output has exceeded the load thats present at 3000rpm.

Good post, I can't explain it any clearer than that 👍

We ran a boat engine on the dyno this morning. 685 ft-lbs at 4500 rpm and 635 hp at 5300 rpm. Very mild hyd roller cam and pump gas compression. Going in a 30 foot cruiser. Should move it right along. I think this boat has a prop but I'm not 100% sure.

Stroker BBC?

Yes, I think it was 568 inches using a Gen VI block and Edelbrock Performer RPM Marine heads. Victor Jr intake with a Braswell 1.59 carb. Cam was only 236/245 hyd roller. Should have great low speed manners but it pulled hard to 5000 rpm.

What headers will be installed in the boat? CMI?

I don't know. I've never seen the boat. I just help with engine design and dyno testing.

Ok, just curious. I've seen a lot of good motors on the dyno, loose 75hp when the owner slaps on a set of stock Mercruiser manifolds when the motor gets installed.

I have used that Lunati cam in a 10.3:1 compression 4.15 stroke 496/440. 950cfm 4-bbl, 2" Super Sucker spacer on a ported Torker II single plane, ported Edelbrock RPM Performer 440 cylinder heads 309 cfm @ .600" lift and our 30" dyno headers 3/4 x 7/8 x 2" step with a 3" collector. 555 torque @ 3,200 rpm, 634 peak torque @ 4,900 rpm and 650 peak horsepower @ 5,800 rpm, 600+ lb-ft of torque from 3,500-5,500 rpm.

Thanks for the feedback 👍But I already had Dwayne spec me a cam, and UPS just delivered it a few days ago., hopefully get it installed in a few weeks.

Please post results, I own a jetboat I would like to make mopar powered!

Got the 2.25" manifolds in, and finished adding 10" of dry pipe to keep the O2 dry with the bigger cam. Off they go for ceramic coating. I will be selling the 1.75" manifolds soon, which will work great for 383-440 cid.

Selling the old 1.75" Hi-Tek manifolds, PM me if interested.

Photo of internal exhaust flapper

Here it is, with Dwayne's 248/248 cam, TFS240 heads, and deep ported Pro Flow XT intake. Also built a new heat exchanger mount, to move it to the front of the engine where it belongs. I ended up installing the 19p/19p impeller stack (developed for the LT4 engine) for more bite and low speed performance, hence the recent decision to go with standard port heads. Gained approx 35-40 ft lbs over the MW-EZ setup, moving the max rpm from 4200 to 4350, slightly more than the KEM LT4.

An interesting note, the datalog now shows about 1.0 kpa pressure difference from MAP to barometer reading with the standard TFS setup. With the MW-EZ setup, it typically showed a 2.5 kpa difference.

Special thanks to Andy and Dwayne for getting this thing lined out, and turned into a TQ monster.