Reply With QuoteNice work John Good post ! JBP
Okay, here’s something I’ve been thinking of posting up and thought I’d follow Tims advice and attempt to get rekindle some activity here.
For some background, we’ve had this boat for about 6 years. It’s a 78 18’ full stringered Brendella. We’ve run the heck out of this boat for years.
The motor is;
2 bolt 454 bored .060 over
Stock cast crank
Stock rods with ARP bolts
SpeedPro Hyper pistons 8.00/1 with 119cc chambers
Clevite bearings
The heads are stock 049 large oval ports with a 3 angle valve job
Compcams springs, retainers and locks
CompCams 3/8 pushrods
Crane pushrod guides
ARP studs
Compcam longslot stamped steel rockers
ARP rocker nuts
CompCam Xtreme Marine Hydraulic flat tappet cam and lifters
Lift .544 & .547 and Duration .270 & .286 with a Lobe Sep of 112
ARP head bolts
Double Roller timing set
MSD billet dizzy and 6AL box with MSD wires and Blaster coil
Bassett twisty headers (ran dry)
10 quart pan with Mellings HV pump and ARP pump driveshaft.
We ran this set up for approx 3 years with great success but then I got the wild hair to totally redo the boat.
I’ve wanted to go with a blower motor for this boat for years and figured that since I had blown the boat completely apart, now was as good of a time as any.
Like so many projects, when I estimated the costs, I shouldn’t have doubled it. I should have TRIPLED it!!!!
Once we were done with the fiberglass work and supplies, paint and clear, new interior, steering, gauges, wiring and controls, I was coming to the realization that money doesn’t grow on trees.
It became clear my idea of a great big motor wasn’t going to happen but I looked at it in a positive light. Since I’ve never had a twin carbed motor let alone a blower motor, I’d rather use this setup as a guinea pig rather than mess something up and grenade/melt down a good motor.
So, I used this always faithful motor to work on refining the plumbing, rail kit, ignition, and carburetion.
We went with an 8-71 Weiand non stripped blower. I’m running a 61t on top and a 54t on the bottom so I’m hardly even working the blower
Two 850cfm DP Holleys with Proform mainbodies, Trick Flow slabbed throttle assembly on a progressive linkage. Primarys are 82 and secondaries are 88s with a 6.5 PV. I’m not boost referenced (I know) so I figured I’d run it fat for protection over the Labor Day weekend coming up and take it easy on it.
Carter 170gph mechanical fuel pump.
Fuel lines are -8AN tee’ing into a fuel/water separator with ½ fittings. From the filter I ran -10AN into the pump and -8AN to the BlowerShop fuel hardline kit. Fuel pressure is a consistent 7lbs (over the winter, I'm going to increase the pickups in the tanks)
A blower balancer with an extra ¼ keyway cut 180 from the stock keyway.
We completed the boat just in time for the end of the season blast over Labor Day and even though it hadn’t ran at all with no shake down runs, all in all we had a great time for 3 days till I lost a head gasket between #4 & #6.
Best we turned was 5400 but no speed numbers at the time spinning an A impeller.
The next day a buddy showed up with a Radar gun and even though we lost the head gasket and a header gasket, we still ran 74.5 at 4800 rpm on a gun the next day and finished the weekend (and maiden voyage) with no major damage, so I’m thrilled.
Now, we primarily use this boat for a motorized air mattress and frankly, I don’t have any desire to go 100 mph in this boat. A solid 80mph boat would be great and frankly, given some time with setup and a healthy head gasket, we’re probably getting close to 80. If I was to describe my driving style in the past, I probably run it wide open for 500 feet and for the rest of the 99.999% time, I'm running it at about 3800 to 4000 rpm. Not a racer by any means (too fat and old)
Given all that, I know this motor is not the perfect candidate for a blower but I’ve got a little money left and am curious what would be all your thoughts assuming that the economy is going to continue the path it’s chosen and my money tree is not leafing out like it normally is?
Let’s say I have between 0 and $2,000 for the winter.
So come on guys, let’s spend my money (wisely) and see what folks think would be a good direction.
Forged pistons?
Forged Rotating assembly (probably not gonna find one for less than $2K)?
Increase the valves to 2.19 and 1.88s?
Different heads altogether? (I have a set of 990s but I dropped a seat on one of them and it’s hard to say what it would cost to save it)
New cam that is more blower friendly (remember, a roller cam, lifters, valvesprings and rocker arms, pushrods are gonna shoot the wad)?
Maybe a good old fashion flat tappet blower grind
ARP head studs?
Stud the mains, convert to 4 bolt or leave it alone with some new ARP main bolts (already have a new set from a previous build that I never used)
Remember, I’m not looking to light the world on fire………….john
Here's the project......
http://i63.photobucket.com/albums/h1...k/DSCN0267.jpg
PS.... the pump is a fresh Panther Energizer from Jet Boat Performance with a A impeller and Place Diverter. Stock Ride plate with skags added for stability. I didnt even have time to check what angle I bolted it to but it appears to be pretty close to 0 degrees.....
Nice work John Good post ! JBP
Weiand blowers aren't noted for making a lot of boost. Swap the top/bottom pulleys to overdrive the blower. A BDS 8-71 (like I used) made 5 lbs at one to one ratio. I have over-driven it on the Nova by 24% and made 16 lbs, thats when it kicked out the headgasket.... I ran the fel-pro 1017s. TIMINATOR
although i just lurk here and i have very little to no knowledge i would appreciate it that this post will stay. i did not read into this post that tim was in any way insulting anyone. i appreciate that anyone withy tims knowledge will come on here and share his experience. i don't even own a boat (but have a 69 chevelle ss) and i check this forum daily. i have a 8-71 bds stage 1 that when finances allow i,m dying to install. too bad i live on the wrong coast!! thanx mike
I'll still be here to answer questions, no matter what coast anybodys on. TIMINATOR
I re-read your last post and we did have some miscommunication, I drew conclusions based on what I read. I recomend that once you build a purpose built engine(I will be here or on the phone for answers), experiment with your current "mule motor" to learn how to tune a blower deal. They ARE different. At this point I think we are all good.... Let the info flow...... Also,I have in the works, an internet/***boat website article to help us ALL understand what we are actually saying, and how to get the most from this site. TIMINATOR
I re-read your last post and we did have some miscommunication, I drew conclusions based on what I read. I recomend that once you build a purpose built engine(I will be here or on the phone for answers), experiment with your current "mule motor" to learn how to tune a blower deal. They ARE different. At this point I think we are all good.... Let the info flow...... Also,I have in the works, an internet/***boat website article to help us ALL understand what we are actually saying, and how to get the most from this site. TIMINATOR
Sounds good Timm, with luck maybe HB will start running coverage on lil boats like it use to. Take care...........john
I hate to interupt a good pissing match, but here is what I would do jrork with the 2gs;
> Buy some alum edelbrock marine heads with inconnel exhaust valves, oval ports.
> Buy a set of ARP head bolts
> Install a set of good quality roller rockers, I like Pro Magnums myself but you have to watch for cheapo knockoffs these days.
> Replace head gaskets with Cometic MLS gaskets sized to acheive a .038 quench area.
> Size the blower drive to achieve 12.5:1 effective compression with your pistons and use 93 octane.
> Set timing between 28 and 30 all in.
BT
I would upgrade the pistons to forged. The hypereutectic pistons are not going to live very long in a supercharged marine application. I would then spend the balance of available funds on the cylinder heads. I would then look at why the head gasket checked out. The timing is the first thing to look at, as too much advance will cause problems. The next thing is fuel. It sounds like the system is sound as far as line size & GPH. Many marine engine have problems due to lean conditions at crusing speeds.
Good luck!
Since you're all still here, let me say this..... I would spend the money on a crank, rods, and good pistons. I would use a more "forgiving cam" with 108 lobe centers. This will soften the powerband down low (so the pump don't skip) and put the 'boost load' easily onto the rods and bearings. You don't need to POUND the motor bearings and pump at 2K RPMs, so why use a cam that does? Hold boost ONLY when you can use it! Cometic or SCE head gaskets, and port matched/big valve ovals or just some nice factory (cheap) big port heads. Look at Isky #Z77 flat tappet cam, I have used that cam in a number of NDBA and IHBA class winning BUDGET boats. "It's easy to make power, but it's not easy to make POWER THAT LASTS"
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