PDA

View Full Version : 330hp LTR Upgrades Mods vs RTP MCX


MariStar-Man
05-11-2010, 10:55 PM
Has anyone wanted to or needed to upgrade this engine to get a llitle more power?

I was curious as the Newer RTP 310hp has the same Cu.in. as the MCX 350hp. Both 5.7 liters

Not knowing too much about performance. Is there any easy mods we can do with our 330hp LTR to bump up the horsepower at all?

russlars
05-12-2010, 02:10 AM
Has anyone wanted to or needed to upgrade this engine to get a llitle more power?

I was curious as the Newer RTP 310hp has the same Cu.in. as the MCX 350hp. Both 5.7 liters

Not knowing too much about performance. Is there any easy mods we can do with our 330hp LTR to bump up the horsepower at all?

Just curious as to why you feel like you need more HP? Mine is a beast just like it is and with the correct prop will go plenty fast and can pull a skiers arms out of the sockets if you are not careful. I think you stated in one of your other posts that you are just learning to wakeboard which requires very little speed or power.:confused:

wheelerd
05-12-2010, 02:24 AM
Just curious if anyone knows what RTP, LTR, MCX stand for?
(The GM engine designations -- LT1, LQ9, L18, etc. -- those I know.)

timvan
05-12-2010, 06:58 AM
Just curious if anyone knows what RTP, LTR, MCX stand for?
(The GM engine designations -- LT1, LQ9, L18, etc. -- those I know.)

LTR is "LT Replacement"

and its the same CI as the other blocks, 5.7 L or 350 ci.

Sombody please correct me if Im wrong, but its my understanding that the short block internals are all pretty much the same...the variations come from the heads, intake and cam for the hard parts and different programming for the soft

wheelerd
05-12-2010, 10:07 AM
Thanks.
I do know that the three engines are all 5.7s, just wondering about the actual acronyms.
Your explanation of LTR makes sense.
MCX = MasterCraft ??
RTP = ?? ?? Predator

87MCProstar
05-12-2010, 10:29 AM
i feel the same way, always looking to get just a little bit more out of something. Russlars, 330 hp in a direct drive (not losing much to drivetrain loss) is quiet a bit of power, but there are just types of us that like hp and always want to try and make things better. i call it Tim the Tool Man syndrome.

dummy
05-12-2010, 10:31 AM
LTR is "LT Replacement"

and its the same CI as the other blocks, 5.7 L or 350 ci.

Sombody please correct me if Im wrong, but its my understanding that the short block internals are all pretty much the same...the variations come from the heads, intake and cam for the hard parts and different programming for the soft

Yeah, pretty much. I'm no Indmar or marine engine expert but I do a fair bit of engine modification and building. Most (not all) GM-based marine internal parts are based off stuff available through GM Goodwrench and/or GM Performance Parts so that's what I'd base any assumptions off of. Blocks are 1-piece rear main seal, 4-bolt main, roller cam, Nodular iron crank, powdered metal rods, 9.4:1 cast pistons. Heads are stock iron Vortec 170cc with 1.94/1.50 valves (not sure about the Predator heads, but LTR/MCX are Vortec).

As for different camshafts, I'm not so sure. If somebody has the Indmar camshaft PNs I can try to cross-reference, but I think the LRT/MCX both use the GM LT-1-based PN 14097395 cam that's used in the Ram Jet crate engine. Stock it's got a 196/206 duration, .431/.450 lift on a 109LSA. I've never popped a valve cover off a MCX but they may use roller rockers in a 1.6:1 ratio over the standard 1.5:1 steel rockers which would bump the lift up to about .460/.480. Just a guess on my part. Otherwise, the MCX uses a different injection manifold and computer programming. Not sure if the throttle bodies are different between the LTR and MCX. I'd be curious to hear from somebody who knows for certain.

That said, my '00 Maristar has the 330hp LTR and I pretty much never give it the full juice. I can't see needing more power than what that boat has stock, but maybe that's just me. :D

X-Aggie
05-12-2010, 03:25 PM
MCX = MasterCraft Extreme

dmminfla
05-12-2010, 05:19 PM
Yeah, pretty much. I'm no Indmar or marine engine expert but I do a fair bit of engine modification and building. Most (not all) GM-based marine internal parts are based off stuff available through GM Goodwrench and/or GM Performance Parts so that's what I'd base any assumptions off of. Blocks are 1-piece rear main seal, 4-bolt main, roller cam, Nodular iron crank, powdered metal rods, 9.4:1 cast pistons. Heads are stock iron Vortec 170cc with 1.94/1.50 valves (not sure about the Predator heads, but LTR/MCX are Vortec).

As for different camshafts, I'm not so sure. If somebody has the Indmar camshaft PNs I can try to cross-reference, but I think the LRT/MCX both use the GM LT-1-based PN 14097395 cam that's used in the Ram Jet crate engine. Stock it's got a 196/206 duration, .431/.450 lift on a 109LSA. I've never popped a valve cover off a MCX but they may use roller rockers in a 1.6:1 ratio over the standard 1.5:1 steel rockers which would bump the lift up to about .460/.480. Just a guess on my part. Otherwise, the MCX uses a different injection manifold and computer programming. Not sure if the throttle bodies are different between the LTR and MCX. I'd be curious to hear from somebody who knows for certain.

That said, my '00 Maristar has the 330hp LTR and I pretty much never give it the full juice. I can't see needing more power than what that boat has stock, but maybe that's just me. :D

Impressive!

wheelerd
05-12-2010, 06:25 PM
Two out of three acronyms solved.
Now for RTP?

Jim@BAWS
05-12-2010, 06:46 PM
Two out of three acronyms solved.
Now for RTP?

RTP

REPLACE THE PREDATOR

At least that is what we made up

Jim@BAWS

wheelerd
05-12-2010, 07:13 PM
Or...
Remember The Plug
Rectify The Problem
Refrigerate The Pabst
:):)

timvan
05-12-2010, 07:50 PM
:cool: Return This Piece

Kevin 89MC
05-13-2010, 11:21 AM
I always think of it as Rear Toe Plate, kind of an odd place for an engine though!