Just curious as to some thoughts here...
My motors are 588ci (4.56 x 4.50), 10:1, Valako fully ported Dart 325s
(flow at .650 is 400/301), Custom RMB cam in the mid to upper 240s with
significant lift, High RPM Morels, 8205PLUS springs at 175# seat, CMI
Sport Tubes.
Here's where I'm concerned: Intakes are Merlin 4150 marine versions that are simply port matched and the carbs are HP1000s (ProSystems) with a 1" 4 hole HVH . The carbs wet flow tested around 898. Not being much of a carb guy I've come to understand that the HP1000 is not much more carb than an 850 so it has me wondering. Also it seems the intakes have fairly small runners from gathered info.
Being in a fairly light boat (Nordic 35) it will literally throw you back in the seats from 3500 to 5200 and then hover around 5300-5400. Like it just stops climbing but doesn't seem like it's ready to. The cam is designed to pull up 5800.
I have a set of ported tall deck 4500 Victors that I can switch to if I purchase some new Doms so I just wanted to get some feed back from some that may have made this swap.
I think MER has had a similar experience on the dyno lately that he kindly shared and thought maybe he could re-share his findings.
Notes:
If it matters my A/F ratio goes from ~13.0:1 4500-5000 and then quickly to 11.6 at 5000-5400.
Also I have tested some props that should have spun higher but they really didn't.
Thanks,
Dave
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10-15-2009 03:27 PMLast edited by Chris; 10-22-2009 at 07:48 PM.
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10-15-2009 04:45 PMHydralic or Solid rollers?
What are the flow numbers on the 325's after porting? why small runners with that size Cu. In?
Cam seems small but I'm not a cam guru. I would expect more duration to give you better top end.
I have forced induction but I have 580 cu. in. with 254/262 and .636 lift, solid roller and it's fairly mild.
I guess the carb could work but that big of an engine I'd go tunnel ram or dom's. but hey, it's easy to spend others money!Last edited by Geronimo36; 10-15-2009 at 04:53 PM.
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10-15-2009 04:48 PM
What is your vacuum reading at 5400? I have a 572 on dyno today with 930 wet CFM 4150 C&S carb making 700 HP when it should be 775-800 HP. The vacuum went up from .9 @ 3200 RPM to 2.1 @ 6200 RPM, l also have similar O2 readings. I just ordered Pro Systems 1150's.
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10-15-2009 05:14 PM
Intakes are Victor 454-TD's custom done by Wilson manifolds,they are Dom base with Wilson 4150 adapters. Heads are AFR 325 with CNC bowls cut down to 114 CC with intake correction make static compression of 9.9 to 1. Cams are from Bob Madara.
Carbs will be here Wednesday I will rerun them and post # then.
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10-15-2009 07:49 PMSince we're on flow, and an engine is a pump, will the CMI sport tubes handle the increased flow of the correct intake and carb?
Getting bad advice is unfortunate, taking bad advice is a Serious matter!!
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10-15-2009 05:11 PMMaybe the carbs are going rich because they're being forced to compensate for the lack of CFM so they're sucking more fuel...
Cam seems short on duration for a 588" NA engine, no?
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10-17-2009 04:41 AM
They are IMO.
Slap a vacuum gauge in there and go from there.
And fuel press...
KISS principle still works wonders guys.,,and that principle separates the men from boys when it comes to engine tuning.
Cam seems short on duration for a 588" NA engine, no?
I doesn´t need to be a bigger cam in a BIGGER ENGINE if the engine otherwise breathes.
Velocity is the key.Last edited by MikeyFIN; 10-17-2009 at 05:46 AM.
Offshore Racing wasn´t designed to be a spectator sport, it's for people or companies with's lots of money to push the envelope of endurance technology and hopefully put a trophy on a mantle. It's man vs the elements, not like boats with like engines running in circles.
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10-17-2009 10:16 AMI can agree to that... if the heads flow well enough and everything else is matched the cam can/will work. PS , bob usually designs his cams base on everything the engine has, heads, flow #'s, intake, spacer etc. I called him about my cam when we were doing the upgrade and the cam he suggested was almost identical to the "shelf" cam we already picked out and his estimated numbers vs. my dyno numbers were very close. He even suggested we could go bigger on the cam but my cylinder heads were the limiting factor.
I'm curious to see what the dominators do and and as suggested, larger intake. Obviously there's a restriction.Last edited by Geronimo36; 10-17-2009 at 10:21 AM.
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10-15-2009 05:37 PMGeronimo...
My thoughts on rich condition are the same
Solid vs hydraulic, apples to oranges. These cams are actually not much less than yours
They were also designed around a few factors such as high altitude, exhaust, etc...
Brian, please post your results!!!
Thanks Guys
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10-15-2009 06:17 PM
On a buddies boat with a similar setup although single engine he gained 300+ rpms going to a 1050 over the 950 holley, no other changes. This was on a 540 with 651 cam (I think). On my 548 I am running an 1150 dom on a merlin X intake, ported Iron eagles and a RM builder(244, 250 630 lift), didn't try a smaller carb to compare but it runs real well and will pull to 6000 easily.
Last edited by Trim'd Up; 10-15-2009 at 06:23 PM.
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10-15-2009 06:39 PMNordicflame, Looked over your post. I had a 604 with Dart cnc 335, 4150 intake and a HP 1000 carb. This was not my original build. Bob and I did the Hi rev lifters as you know along with his cam. We were expecting to pick-up from 734 hp to about 775-800 hp. I made a pull after the break-in and only made a 6hp gain, I was like" what the he--", called Bob, HEY ARE YOU SURE ABOUT THIS CAM? We talked about it and decided lets try a dfferent intake and carb, I had a dart 4500 ported on the shelf and a Holley 1050 that was just used on a 800hp solid roller engine. Gave it a shot, first pull 775 second pull 815 hp @ 6000rpm. The original run didn't go rich, it just was weak and fell off. Didn't you run on dyno first? If so, what results did you have at that time. Talk with Bob, see what he says about this.
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