Exhaust logs

[JayBee]

So, are all exhaust logs about equal? I've noticed mine (Glenwoods) have a pretty nice "looking" flow pattern with the runners sweeping into the log and a nice progression in log diameter. Others that I have seen pics of look more like plumbing fixtures with no sweep in the runners and a constant diameter. Is any one brand better than another?
Also, how about the Mercruiser style manifolds? Do any of those flow well? How do they compare to the logs?
Obviously headers are the best performance choice, but I have a closed engine compartment and cannot afford fully water jacketted headers right now. I plan on ditching the snails and fabricating madrel bent tubes that make a loop that would be a little larger in diameter than the exit of the log. Just wondered what the best economical choice was...
Thanks,
Jason

[Old Guy]

The Glenwood logs that I had came with risers that could be cut off so as to provide a 3" ID discharge. This would result (if you used the option) in the log exit (3") and the riser exit would be the same. This must be an improvement. It will require the use of 3 1/2" hose and new tips. I got some 4" muffler/tips that had a 3 1/2" inlet. It can't be even close to a set of good headers. Headers were not an option for me.
http://files.triton.net/old1/new_pump.jpg
It seems to work pretty good. It's a different boat and the Glenwood logs wouldn't fit, so I have Hardin logs with Glenwood risers and blah, blah... Anyway, from Glenwood risers back it's the same stuff.
old

[sidewound]

JAYBE,
OLD GUYS option is what I did with mine. I built my own stainless exhaust tips and now have to cut new holes on my transom since I converted from the original square berks to hardins. I agree that it's gotta help. If ya just wanna tinker at goin faster it's an option to look at. Won't cost an arm and a leg either.
I've been in his boat and his 455 was turning at 5K! Not bad!!!
PEACE MAN :cool:
CESAR
[ July 09, 2003, 08:23 PM: Message edited by: sidewound ]

[BiggusJimbus]

This is the only non-log, non OT header's I've been able to find.
http://www.rewarderheaders.com/search_result.asp?CATEGORY=ALL&MANUFACTURER=Thru-Transom&DESCRIPTION=&PRODUCT_ID=
They are not water jacketed, so you can't put them under a cover. I like the idea of the 40 or so HP that I could claim by ditching the logs, but so far, this is the only alternative I like. I'd still like to keep my cover. I've burned myself enough on the pipes for a lifetime.
[ July 09, 2003, 09:33 PM: Message edited by: BiggusJimbus ]

[JayBee]

Well, I totally screwed up and quit bidding on a set of CMI completely stainless fully jacketted headers on Ebay a few weeks ago. They went for $630 (my last bid was 625) and if you check out the custom marine website they sell for about $2500 - $2800 new!
Something that just occurred to me - when everyone says you can't use injected headers under an engine cover are they talking about the little doghouse style covers or any covered engine bay? My engine bay is HUGE - I think I could get to BBC's in there side by side (hey, there's a thought!). Plus there is quite a bit of air circulation.. Here is a pic:
http://webpages.charter.net/jlbarnes/boat/BOATEN~1.JPG
So, are you guys not running any risers? Any problems with water getting back to the engine?
Thanks,
Jason

[JayBee]

Here is the website for CMI - and pretty much the headers I missed...
Custom Marine (http://www.custommarine.com/html/standard_elbow_top_systems.html)

[HOOTER SLED-]

Typically on a jet set-up the motor sits lower than the water line, that is why you need snail risers to prevent backwash. Whereas v-drives usually have those small angled risers because the motors sit above the water line. I've never had a problem with backwash. I make sure I always keep my flappers fresh. I also slow my boat down nice and easy and turn as the wake comes back up to the transom. Giving it a little snap on the the throttle helps too when that wake comes back up. I may be replacing my logs for Imcos or Lightnings. I have a small box because I have small jumper seats on the sides of my motor. May have a clearance problem. Might have to wait. I may just redo the whole interior with a new rear hatch. It's a shame, my interior is still in damn good condition too. I need to make room for some motor upgrades anyway.
HOOTER

[PLACECRAFT20]

I DID THE SAME UPGRADES AS OLD GUY. I CUT THE ENDS OFF OF THE SNAILS. THIS GAVE A APPROXIMATELY A 3 1/4 I.D. I USED 4" STAINLESS TIPS WITH A 3 1/2 INCH REDUSER. THEY HELPED PERFORMANCE AND SOUND GREAT. WHEN I CAN AFFORD THE HEADERS I WILL JUST CUT THE REDUSERS OFF THE TIPS. IF YOU WANT PICTURES LET ME KNOW.

[BiggusJimbus]

I'm sorry,
I failed to mention that I was referring to the choices of headers for OLDS. For most everything else, there are many choices.
I would say you could run pretty much any kind of headers under the type of hatch that you are referring to. But it would still be wise to consult the manufacturer.
Jim.

[checkmate76]

Why do the through transom headers have to be so expensive? all they do is bend some pipe weld on the collector and some holes for the water injector tubes. hell you can buy ceramic coated car headers for $200 same darn thing!
what gives? burningm