Moneyshott

iTrader: (1)

Hi, Looking for some help here. I have 04 LS6 which is basically stock that I am looking to do a cam upgrade on. I have it in a jet boat. Right now I can get it to turn about 5k. I am going to put a new impller on it to get some more rpms out of it but I would like a cam that has alot of mid/top power around 4-5500 rpm to match it. (if some how i can get to 6k great, but I dont see it happening in a jetboat). Looking for a choppy idil and about 30-40 hp gain.
This is my current set up:
04 ls6
stock cam, heads, bottom end w/ all arp fasteners
750 cfm holley
Edelbrock single plane intake w/ MSD box(curve pills,non-programmable)
1.75 rockers
open wet exhaust, no baffles

Thanks, Keith

Ryan L

LS-based motor making peak power at 5k? I'm curious to see what others have in mind... However, I DO know that the stock LS6 cam is a terrible choice.

I'd change the title of the thread to get more views though... "Best cam for 5k rev" or somethign similar.

c0ncEpT

iTrader: (4)

My question is why can you only get it to 5,000 RPM?

If you were able to spin it into the 6,000-6,500 range I would say throw in something like an MS4, Vindicator, or a TREX

Moneyshott

iTrader: (1)

Well generally in a jetboat. What ever it turns on the street its about a 1000rpm less pushing a jet, whatever motor it is. Especially a small block. Thats why I need a big boost in the mid aswell as the top range.

1sick'98WS6

iTrader: (19)

Ms4 will make **** loads of power in that area

c0ncEpT

iTrader: (4)

If you were to get your heads milled a bit and use even a 224 cam I think you would make lots of power and torque in the range you need to use it in.

Old SStroker

IMO, the single plane runners are wrong for the rpm range you are looking for. The LS6 intake or the truck intake (fugly but it puts out) and EFI would be much better, but I am assuming you want to stay with a carb. That's too bad.

Converting to EFI isn't all that much trouble with the stand-alone systems available. Consider that a correct valve job on the 243 heads, the correct HR cam, stock rockers and lifters and the truck/LS6 intake will net you much more than the 40 hp you seek. The down side is the idle won't be very lumpy, but the boat will be fast.

More power in the under 5K rpm range should spin the impeller you have a bit higher, but then you could change impeller to allow the engine to run where it makes best power.

I'd contact someone who knows what to do as described above. There aren't many, because most are building for max power at/above 6000. There are a few, however.

Basically you are building a truck engine that hauls "mules".

My $.02.

Moneyshott

iTrader: (1)

The ms4 sounds nice , but seems large. The guys at comp cams told me I should stay under .600 lift. But im no cam guy that is why im asking. I was thinking the ASA cam was nice, but i would like to see some more lift than .525......

Moneyshott

iTrader: (1)

I know injection would be alot easier in the long run. But they are making good power with these setups. Just gotta dial it in........(the story of my life)

Dave 96TA

iTrader: (10)

Try a custom cam to fit your needs. There aren't any off the shelf 'LSx cams for use in a jet boat running a single plane intake and carb tuned to 5000rpm'. Some members here are pros at cam suggestion, for a small fee.

Moneyshott

iTrader: (1)

Yeah. thats what I will prob end up doing. Just trying to get some more input before I do.

Any dyno data on the ASA cam?

cellulis44

iTrader: (11)

boats need need awsome torque.. I dont recommend a peaky as cam. AT ALL.

something with a tight LSA is going to give the mid range punch to get it on plane in a heart beat. I'd say something in the 218/224 range with around .580 lift and a low lsa.. you wont have idling issues with a tight lsa because jet drive dont have that much resistence.

btw... I used to be a marine mechanic

Compressor Surge

iTrader: (21)

I want to see some pics and info on this boat!!!!!!! I've been wanting to do that (LSx jetboat) for a LOOOONG time!!!! Sounds sweet!!

5_02ls1

iTrader: (20)

somthing like the tr 224 reverse split....230/224 on a 111 ive read that cam has a killer tourqe curve.......my old vinci 220/224 551/551 114 was a tourqy cam had a stock like powerband with a couple hundred extra rpms,and i ran it on 04 ls6 springs......

you may wanna search around on the truck board.....

id stay away from big cams such as an ms4.....they will not help you at all......

PowerTalk

Speak to the guys that do this sort of thing for a living. Not blokes on a car based forum

Ryan02SS

iTrader: (3)

Like was mentioned in a jet boat you need torque to spin the impeller. Even with an impeller change you will not be able to spin much past 5000rpms with small block torque. There's a local guy at the lake that runs a 588ci BBF 13.1-1 Compression, 101Blue, well over 600Hp and can only spin 5800-6000rpms.

I recommend something along the lines of a 208/218 .563/.598 110+4 for max torque production along your rpm range. You need alot more exhaust duration and lift with marine wet exhaust vs car exhaust. The bad thing about the above cam is, will it work with wet exhaust without getting reversion? Maybe, depending on the length of your risers and where the water mixes. You might have to cut it on a 112+4 LSA to reduce overlap.

I run a 234/240 .580/.568 112+4 in my 385ci SBC in my boat. I also run 22" long dry risers to prevent reversion. I have AFR heads and spin it to 6000rpms @ 78.2 GPS. Alpha SS 2.5" shorty outdrive.

http://www.youtube.com/watch?v=fyKTqEhzfCc

http://www.youtube.com/watch?v=vuL_dEX0SoM

Moneyshott

iTrader: (1)

Wow. Thats a killer motor..Whats the specs? Is it really going to fit in that boat? if so what kinda cam you gonna use custom grind or shelf?

Thanks for the cam input. At first I did like the reverse split, but I will give it another look over. I will take some more pics when I can. The boat is in storage right now.

S10xGN

iTrader: (11)

I wouldn't think a boat is much different than a car. In a car you build the engine to run in the RPM range YOU want, then adjust the gearing to get it down the track. In a boat, you'd change the prop or impeller.

Russ

PowerTalk

LS7 Aluminium Block
F2 Procharger
Direct drive for blower ( No Belt )
4 fuel rails
Custom 16 Injector Methanol Manifold
GMM Custom cam
Dry sump 1.8 inches high
GMM custom motor plates
electric light weight water pump
8.9 inch lightweight flywheel and remote starter