PDA

View Full Version : What Exhaust



skijake
06-13-2001, 09:04 AM
I'm building my first blown boat. A Hallett Vector. It will be used for some speedskiing and racing and some cruising.
My only two final questions are which outdrive to use? and what exhaust?
I have heard great things about the Imco Powerflow Plus and told that they can make more H.P. then most S/S tube headers and that they don't end up leaking in two years.
I'm also considering a set of Lightning headers. They look meaner and being from the old school of racing they seem to me that they would make more Horse Power.
What do you think?
I do have limited funds.
Thanks for your answers

dcraig
06-13-2001, 09:39 AM
How much HP is your motor going to make? Whats the displacement?

skijake
06-13-2001, 11:46 AM
Sorry I did forgot to put it in the original write-up. I should be making between 850 to 900 horse power and have 490 cubic inches

dcraig
06-13-2001, 12:59 PM
For that kind of power, the Bravo 1 drive is not going to do it. Better anti up for the Merc's number 6 drive.

boatnam1
06-13-2001, 01:53 PM
whats up skijake,hows the refinery life?hey i have a blown 468 making around 800 ponies and i have imco powerflow and they work good.but if i did it all over again i would get lighting"s.you will want to do your outdrive for sure it wont last long believe me.and if you get it done you can get pretty good money for your stock stuff.i did mine at quality performance in corona.they did a good job.ofcourse i didn't get it done until i blew all my gears apart!uppppps live and learn.

boatnam1
06-13-2001, 01:55 PM
hey skijake,one other thing imco also sells a brand new drive all done up for 13,000 if you dont already have one.if you already have a bravo it costs 4400 to get your drive done right.

skijake
06-13-2001, 07:44 PM
Thinking about getting a Xtreme drive from Imco. with the X-deminsion that I already have I could use a two inch shorter lower housing.
Wish I could get a No. 6 drive (maybe if I win the lotto tonight)
What make you want Lightnings over the Imco Powerflows??

ponponracing
06-13-2001, 08:43 PM
Skijake,
900 horses is a big big big number for a 490 ci motor. I guess you run a lot of boost with huge ported heads and you will run big gas also.
I did run those numbers with a Bravo drive (no upgrade) at one occasion and I could see that the base of the gears was ripping off. In fact, after blowing three Bravo, we decided to tear down and inspect the drive before it blows and it was the only time we could see what was exploding first. The other times, the drive was so damaged that it was impossible to find out were the destruction started.
But now there are upgraded drive (Bravo or equivalent), and if you want to stick with a small drive, you should considere one of those. A 6 DrySump is the thing to use with that kind of power. More money in a drive, but three Bravo are also expensive. Plus the fact that you are always towed back to your trailer....

dcraig
06-14-2001, 08:23 AM
That's I think also. A #6 is expensive, but in the long run, it will be more economical. (AND MORE FUN)

MrHavasuCat
06-27-2001, 02:20 PM
I am running about 800 hp on a blown cat with a bravo xr upper, and teague lower. the drive is holding up fine. I have a friend running a whipple quad rotor 509 in his cat (detuned to 880 hp), he is also running an xr without problems. An xr will run you about $10,000.00 and a #6 drive is about $30,000.00, not to mention weight and having to run a transmission. If you don't beat up on the drive to bad I think an xr would be a good choice. As far as exhaust I am running imco power flows w/ brodix aluminum heads. My engine builder will not use standard headers because they crack.

TinMan57
06-28-2001, 08:17 PM
I've got a question. I'm new to IO's and am learning as I go. In the post above this one some drive prices are given. Is this price above a Bravo or instead of a bravo? And what is the order of good, better best when using the names of the various drives?
Thanks.

Havasu Hangin'
06-28-2001, 09:26 PM
Originally posted by TinMan57:
I've got a question...Is this price above a Bravo or instead of a bravo? And what is the order of good, better best when using the names of the various drives?
I think MrHavasuCat is referring to a $10,000 price tag on a new Bravo 1 XR drive. I'm not a Merc Mechanic, but I'll take a shot at drive names:
Alpha 1- mercs entry level drive- low horsepower, usually small blocks. Bayliner class.
Bravo 3- twin propeller, counter rotating, surfacing drive. Patterned after Volvo's Duoprop. Works good on air-entrapment (cat) hulls. Shallower x-dimension (prop height) makes for more efficient top end. Sport boat applications.
Bravo 1 XZ- Mercs standard, big block drive. Good up to around 500HP. Performance boat applications.
Bravo 1 XR- Mercs factory racing drive. Mostly the same as the XZ, only with straight cut gears. High performance applications.
Number 6- Big boy's toy. I think they give you testosterone supplements with every purchase. http://free.***boat.net/ubb/eek.gif "Huevos grande" applications.
For high performance boats, XZ-good, XR-better, #6-best. Drive prices vary, with IMCO or Teague offering beefy Bravo 1 upgrades as mentioned above.
Hope I didn't confuse you too much. http://free.***boat.net/ubb/cool.gif http://free.***boat.net/ubb/cool.gif http://free.***boat.net/ubb/cool.gif
[This message has been edited by Havasu Hangin' (edited June 28, 2001).]

TinMan57
06-29-2001, 02:26 PM
No confusion at all, thanks for the reply. I've been crew chief on a Blown Gas Hydro (184 mph) and now I crew on an Alcohol Hydro(218 mph), but all my pleasure boating untill recently was jet. Two of my friends just bought IO boats and I'm trying to get up to speed with all the new terminalogy and speed tricks.

Havasu Hangin'
06-30-2001, 02:37 PM
Hey TinMan57, sounds like you have a rough job! http://free.***boat.net/ubb/rolleyes.gif By the way, thought you might like a little history, as well:
Bravo- The XZ and XR designations are new to 2001. In prior years, there was just the "Bravo 1," which is why aftermarket guys were beefing them up with hardened shafts, gears, etc. for big horsepower reliability.
Number 6- These drives are all hand assembled. A couple years ago, Merc came out with a "dry sump" oiling system. It seems that the oil immersion was costing 25+ horsepower loss, so they went with a system that sprays oil on to the gears. Not a true "dry sump" (the pump is driven off the shaft), but close enough. As MrHavasuCat mentioned, they (with a transmission) are very heavy, and can be recognized by their distinctive large profile (skeg).
Hope this helps. Happy boating, even at 218MPH...
http://free.***boat.net/ubb/biggrin.gif http://free.***boat.net/ubb/biggrin.gif http://free.***boat.net/ubb/biggrin.gif

skijake
07-01-2001, 05:35 AM
Thanks for all the help.
I drool everytime I see a #6 drive.
Love to have one but the cost is out of my grasp.
I've been looking at a few set-ups that some shops are putting together with a XR top. some aftermarket shafts. They seem to be giving them alot of horsepower and abuse and they are staying together for the most part.
They cost less then a #6 drive and don't have to put in a trans. I looked into a #3 and #5 drives but they still break, cost alot and need a trans.
Still looking if anyone has the magic answer and still kicking around what headers to use.

MrHavasuCat
07-02-2001, 02:48 PM
Rumor has it that merc is coming out with a new drive rated at about 800 hp with internal hydraulic steering. I was told the price should be a lot less that a # 6. That would be great, hope it is not just a rumor.
[This message has been edited by MrHavasuCat (edited July 02, 2001).]

skijake
07-11-2001, 01:24 PM
Thanks for all the help.
Think I'll go with the XR top end with a two inch shorter bottom case from Imco. 1.50 XR gears in top and 1.36 gears in the bottom.
Still kicking around the exhaust
Thanks again, see you at Havasu

BLOWNDRAGBOAT
08-08-2001, 04:17 PM
BLOWNDRAGBOAT SAYS THIS: Go with the lightning headers but be prepared to wait. Last time I spoke with them about one of my customer engines, there was gonna be a wait. They are behind on production due to high demand and they are cheaper than say Imco or GIL. Besides they look trick as hell. Call BAM marine in florida. The number is in the bcak of ***boat mag. How did you come up with those Horsepower figures? What kind of blower are you running to get that much power? In anycase, you should rethink your setup. To get that kind of power you will need to either over drive the hell out of it to get the boost for those kind of numbers. You will need to run a superchiller to get the intake temp down or the party will be over due to detonation. I would recommend using a 10:71 blower @ around 5 pounds of boost. You will still need to run a superchiller (around $2000). Running a bigger blower at less boost will make you alot happier or at least your pistons,rings and crank alot happier. Without a dought a #6 is the trick setup but man those things are steep. With what your trying to accomplish, I certainly hope you have an open line of credit at the bank. Big blower motors and outdrives? YIKES!!!!! Heres something you might wanna try. Have you considerd running an Arnesson surface drive? Those things are trick and I think they can be found cheaper than a #6 drive. A surface drive will hold up for sure!!! One more thing...If your looking for a handle on parts go to OFFSHOREONLY.COM and go to the classifieds. TONS OF STUFF that you may me interested in....Everything you can think of from blowers to outdrives and everything in between. Hope it goes well for ya....

pebo
08-29-2001, 09:21 PM
What movie is playing at havasu this weekend

skijake
08-30-2001, 09:21 PM
Steve any request???

SPECTRABRENT
08-30-2001, 09:43 PM
SkiJake,
I run a Spectra 20 Berk Pump with a 509 Chevy and IMCO Powerflow Exhaust, They work great.
Brent