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.