Thread: CMIs on 496 HO-Myth or Real?
Results 21 to 40 of 54
-
- Join Date
- Oct 2008
- Location
- Lake Travis Texas
- Posts
- 6,844
01-16-2010 10:57 PM
-
- Join Date
- Nov 2008
- Location
- Where the summer never ends
- Posts
- 4,346
01-16-2010 11:15 PMI think this is like everything else.......
the parts and boat and prop need to match 100% then u may see a gain in a better exhaust ?!
If nothing really is dialed in u won't see a differents in just changing headers exept for maybe sound. LOL
-
01-17-2010 09:22 AM
I really don't think that the stock 425 hp 496 needs the extra breathing capability. Mine had the aluminum exhaust and the ports were huge. I really wanted to tell myself that after spending almost 5 big ones and doing all that work that there was some improvement but that fact is, there wasn't. My advice is to save the money unless you are redoing the complete motor or have an extra 5 grand laying around to blow on bling. To keep publishing these claims of 4-7 mph on a single engine boat just to sell more headers is not cool.
-
- Join Date
- Nov 2008
- Location
- Where the summer never ends
- Posts
- 4,346
-
01-17-2010 11:10 AM
Hmmmmm....Guess those were bogus dyno sheets I was looking at ???? They DO create almost 60 HP on the sheets I saw. If I remember it was 57. On a second note, put the riser off your stock 496 risers and look at the anti-reversion ring inside. With this ring your exhaust is restricked to about 2 " in diameter.......pull the rings out for the price of a gasket set and you will see good gains but forget about your warranty after.
Only two defining forces have ever offered to die for you: Jesus Christ and the
American Military. One died for your soul, the other for your freedom.
-
- Join Date
- Oct 2009
- Posts
- 40
01-17-2010 06:33 PMNot real world wet prop hp results like Ray said before. I think CRC had switchable exhaust as well which would also hurt any gains. I dont know to. Did you keep the switch exhaust after the CMI were installed?
35-40hp in a Donzi 22 classic should have given you a noticeable top end increase.
CRC, I also think your move the the 525 was probably more like 130+hp increase at the prop. Those 525s are nice.
-
- Join Date
- Dec 2008
- Posts
- 27
01-18-2010 05:23 PMSince all of the dyno results are faked, call Teaque for real world "non dyno" boat results.
-
- Join Date
- Nov 2008
- Location
- San Diego
- Posts
- 102
01-19-2010 12:26 AMI am not saying any dyno results were faked here! As many of you know, there are different ways to set up a dyno calibration on any given run and also depends on how the engine is equipped on the dyno, when was the last time the dyno was calibrated, etc.,etc. We tried very hard to use SAE standards on our dyno tests, a properly calibrated and tested dyno and running the headers wet for real world results. How others ran their dyno tests on what in testing the CMI's with those dyno runs, I don't really know or care. What really counts is how the various boats and engines respond in the boats and under real world results in a lot of real world boats the results were for the most part as follows: 1. no change in performance. 2. 1-3 mph increase in performance. 3. A nice cool idle sound and lots of bling.
These are the results that really count, everything else is just talk and dyno numbers! You can take that to the bank baby!
Best Regards,
Ray @ Raylar
-
- Join Date
- Oct 2008
- Location
- West Michigan
- Posts
- 37,861
- Blog Entries
- 45
01-19-2010 06:33 AMI would think the 35 - 40 hp you got with the CMI's only would be a pretty decent gain. I certainly would not be pizzed seeing a number like that.
Getting bad advice is unfortunate, taking bad advice is a Serious matter!!
-
01-19-2010 10:31 AM
For the $ on a 496HO I don't think it's worth it. IMO. When I did a set of sport tubes for a customer a few years back they were around 5k with the quick and quiet tails. That was just the initial cost.. Doing the re&re in a 22 classic is a bit of a b!tch. Also the fitment wasn't great and you lose the ability to pressurize and drain the raw water. They're heavier then the stock manifolds as well. With the headers, labbed prop, and K&N we picked up 2-3 mph. It's hard to say what the exhaust alone did, I should have tried a back to back test. On an older Z25 with an HO I removed the turbulators, spent an hour or so porting the stock exhaust where it merges at the riser, and had the rev limit raised. It picked up 1.5mph for a fraction of the cost. The CMI's do look nice though, and sound better too.. I guess it all depends on your budget..
-
- Join Date
- Dec 2008
- Posts
- 27
-
01-19-2010 12:46 PM
Dyno / lab condition is just that. "Maximum" possibility within controled environment. Just like Ray was stating. As far as ANY CMI systtem... run like hell. Sooner or later, you will be buying a new motor.
However there is a nother way to look at the so called HP gain issue. Any given motor, let's say 496 or a 502 will put out "X" amount of HP. Unless it's blown, but from a 502 block the max theoretical HP you can get is (I assume) +- 1000HP. not you start "loosing" HP with all the moving parts. So I don't think it's how much HP an engine is gaining.. it's more like how much HP you'r not loosing.
Power steering pump, oil pump, fuel pump, alternator, rocker arm/lifter movement, rotating counterwieghts, pushing out exhaust. etc. Now you'r down to 1000 HP minus all HP lost to the motor actually running and working.
So.. the least HP you loose, the more HP you have for the props. I don't think HP can be "added" (again, unless it's blown or something) it's how little HP you loose adding High Perf. parts. You can't get a V-8 to get you a V-10 performance with all things being equal. No HP gain.. less existing HP lose is the name of the game. In my .02Last edited by PARADOX; 01-19-2010 at 12:52 PM.
Life is: what happens... when you plan something else.
-
01-19-2010 03:44 PM
Pismo, yes I have Q&Q which I only use at idle or minimum planing speed now. I also had it to begin with so I don't think that it would negate any power gain. Ray, your input is always appreciated. I never said that the dyno sheets were fudged; Just wondering where all that extra hp was? As much as I wanted to say that I gained something the fact is that it did nothing for my boat's top end. I changed nothing else when I did the headers and I saw no gain.
-
01-19-2010 09:13 PM
CRC; I have debated this on forum's and in my head over and over. My finding are exactly what you say....no real world gains. In my mind, the ONLY way one could gain MPH is by being on the very edge of a prop selection...say running a 24P at 5050 RPM and doing 65 MPH. Now adding the CMI's net you a few RPM's and now you have to run a taller prop i.e 26P and can turn that at 4900 or 4950 at 67 MPH. That would be the only way I could see to gain anything. I have chosen to go a different direction with gain with an extension box.
Nice thread
-
01-19-2010 09:17 PM
Thanks. I chose a different direction too...
http://www.youtube.com/watch?v=i7H6zNFH8f0
-
- Join Date
- Nov 2008
- Location
- San Diego
- Posts
- 102
01-20-2010 01:49 AMI guess I am always amazed how sometimes the stock 496HO 425 gets compared to a Mercury Racing HP525EFI. Heck, that comparison is really an apples and oranges comparison.
First the HP525EFi is 540HP right outta the crate, thats 115 more than the stock 496HO. Yah it should make more power and speed it has more. Its also a hell of a lot more expensive, ie the apples and oranges comparison!
Just some food for thought here. Raylar took two absolutly stock 496 MAGS !! for Sunsation, $5K less than 496HO, equipped them with the Raylar HO525 standard off the shelf kits and stock exhausts and reprogrammed the ECM's and put some nice bling on the engines with powder coating and relocation kits. Sunsation installed them into a 32 SSR (awesome boat!)Sunsation with standard BRAVO 1X drives and Hawkeye took the boat to LOTO last year and ran 96 MPH. Just a mile or two faster than the same boat with HP525EFI's with Bravo XR Sportmasters. How did that happen, well its because the 496's properly upgraded will run with or outrun most HP525EFI's especially when equipped with a good set of headers like the HP525EFI.
Don't believe me, call Joe at Sunsation or the guys a Hawkeye Boat Sales and they will confirm along with all the other observers at the Loto Shootout!
Whats the point, a customers wallet will have a fatter side view due to the extra cash still in there! About $40-50K on the average twin engine boat!
If that cash ain't important to Ya, Could I please get you to put in in a plain envelope and donate it to the Raylar needs capital Foundation, we accept all chartible contributions!
GET your 496 up to comparable numbers, then lets make the comparison!
Best Regards,
Ray @ Raylar
-
- Join Date
- Dec 2008
- Posts
- 27
01-20-2010 11:26 AM[QUOTE=Raylar;419482]I guess I am always amazed how sometimes the stock 496HO 425 gets compared to a Mercury Racing HP525EFI. Heck, that comparison is really an apples and oranges comparison.
The comparison is to a GM HP3 8.1 engine, not the 525, I know the difference.
-
01-20-2010 12:48 PM
I'm not comparing the 496 to the 525. It's just the route that I chose to go after talking to a lot of folks. I found a vintage 2007 motor with 30 hours for 20 grand. That's all I'll say here since my intention in starting this thread was not to compare engines but to discuss the claimed power gains from CMI headers on the 496.
-
-
- Join Date
- Dec 2008
- Posts
- 27
01-20-2010 04:04 PMPage 8 of our catalog at www.custommarine.com shows four of the many results responces from customers. Teaque also ran 4 or 5 quantified before and after header installation tests with great results, you can call him at 661/295-7000. I myself have no need to make up data, after 100's of 496 header installations and 25 years of this job, it would not be worth it.