Vortech Blown 509" BBC jet boat engine.....

[502 JET]

Well its been a little longer than a year (and big pile of money) and I finally have my engine done. This was the first time I have ever had an engine built and dynoed and probably the last. I was having belt slipping issues with the original 10 rib serpentine setup and was on the dyno on three separate occasions. Needless to say this was a ton of money for dynoing. For the final dynoing and tuning I installed a cog drive.
http://www.hotboatpics.com/pics/data/500/15596DSC00446-med.JPG
http://www.hotboatpics.com/pics/data/500/15596DSC00443-med.JPG
If my scanner was working I would post the dyno sheet.
At 3700 rpm the engine made 517 hp and 734 tq. This is where they started reading the power.
At 6000 rpm 916 hp and 801 tq. This is the intended max rpms.
Max hp at 6000 rpm 916 and max tq was flat through 5000-5600 rpm at 814.
All this on 93 octane pump gas!
This was run at 9.6 lbs of boost. The engine was tested at 11 lbs and it made 980hp but was getting beyond the pump gas limits with no inter cooler.
Timing was locked out at 34* with 1/2* set on the MSD 6BTM. So with each lb of boost the timing was retarded 1/2 of a degree.
Engine is a gen6 502" bored to 509". It started life as a450hp 502 that pushed my boat to 75mph.
GM Block GEN6
GM steel crank
Brodix BB2X Heads with cnc chambers, bowl blend, and intake port match
Full solid roller Lift .663 in .663 ex. Duration @.050 252 in 260 ex.
Manley H beam rods and Manley pistons 8.5 to1 compression
Vortech V4J compressor blowing into a Procharger carb box with 2 450 holleys
Now I need to complete the supporting mods to the boat so I can install the engine. I already enlarged the fuel tank pickups from 5/16" tube and 3/8" hose to 1/2" tube to #10 hose.
http://www.hotboatpics.com/pics/data/500/15596DSC00434-med.JPG
Now to get the tanks back into the boat and plumb the fuel system.
I still have to build the pump. Waiting on a AA stainless impeller. If all goes well I may be on the water by the end of June........Was a 502 now a 509......

[Warp Factor]

Interesting project. The centrifugal blower should take less power to drive and result in lower intake temperatures than a roots at the same boost.
Can't tell from the photos........are you running carbs in a pressurized box, or fuel injection?

[502 JET]

There are two Holley 450's inside the carb box.

[tbanzer]

Just an observation, but I would look at moving the idler pulley to the outside of the belt. This will put more belt in contact with the blower pulley to help with belt slippage.

[502 JET]

I need to get a shorter belt. The belt was fine with a 77T crank pulley but it was making too much boost and had to switch to 73T.

[Infomaniac]

:D :D :D :D :D
Congrats man. Great Job

[texas-19]

how was your fuel distribution?Did you have any issues with those carbs and that intake?

[502 JET]

There were no problems with with fuel distribution, the egt's were all equal + or - a few degrees. The AFR were running 11.7 and 11.8 on each bank at 6k rpm.
The carbs and box were designed to bolt on to an Offenhauser 360* dual plane dual quad intake. I modified the adapter to fit the tunnelram.
My engine builder has made 1500hp with same carb box and carbs on the Offy intake with lager cubic inches and intercooling.

[franky]

what are you doing for fuel delivery? Pump, reg, pressures?

[502 JET]

It may make your head spin.:) But I will try and explain it. I take pics when I get to putting the fuel system together.
I will be running -10 hose from each tank to a 1/2" y-block and into a 1/2" fuel water seperator. Out of the seperator into an Aeromotive -10 filter to an A1000 pump. Out of the pump with -10 hose to the regulator. Out of the regulator with -6 hose to the carb feeds.
I have an Aeromotive boost refrenced return style regulator that increases the fuel pressure 1 to 1 with the boost. The fuel will return with -6 hose through a cooler and back into the other in port on the water seperator. The cooler is to help the pump stay running cool and hopefully lasting longer.

[franky]

I have the same (sorta) setup but with two regulators. One to drop the (EFI) pump down to 25# and the other boost referenced. It goes from 7# (no boost) to 17# (10 pounds of boost). The return goes through a (Merc PS) cooler and back to the inlet of the fuel/water seperator. I do run a big intercooler I made from two Spearco cores, added about 70 HP on dyno. The set-up does look frankensteinish but works. Also have the boost retard MSD. Only one 1000cfm carb, 810HP idles at 600 RPM. I will post a pic.

[Reapers]

Very nice. Alot of people are going to the centrifugal superchargers lately. I have been running them for over a year with great results. 575 ci, dart pro 1 ported in house, hyd roller, kryptonite, oliver rods, je pistons and m5 intercooled. 13 # at 6500 made 1069 on 91 octane. Idles awesome at 800 in or out of gear. Great luck and hope you play it safe to begin with. Remember heat soak is not measured or contemplated on the dyno. Play it safe with timing. NICE

[Jspeeddemon]

Hey 502 this is John, I am the guy you bought the box and carbs from. Looks like you have it dialed in well for your setup. A buddy of mine had the issues with fuel distribution with the carb setup inside the box. His fix was to mount the box on a tunnel ram, it worked wonders for equal fuel distribution. Add a nice intercooler and crank up the boost. i had moine repaired by a guy that will build you one relatively cheap compared to a new one. I would be a little scared of 34 degrees timing on pump gas with a supercharger and no intercooler. Are you mixing in a little race fuel with that? Would be some cheap insurance to not having a burnt piston. Did you play with the timing on the dyno, did it repsond to timing, how did you arrive at that timing number?

[502 JET]

Hey John sorry for the late reply. Been busy trying to get the boat together.
The carb box worked out great! Thanks again!
When the engine was being dynoed they tried different timing settings on the boost retard. The way it is now it will pull out 1/2 of a degree of timing per pound of boost.
At 1.5 on the boost retard and the HP dropped to 868hp @ 6k rpm.
At 2 on the boost retard and the HP dropped to 832hp @ 6k rpm.
At 11 psi the motor was making 980 hp but was getting beyond the pump gas limits, non inter cooled. Race gas is not an option, too much $$$$$. So the boost was backed down to 9.6 lbs @ 6k rpm. The inter cooler is another $1500 its something I may get in the future. For now I will just keep it detuned so it lives.....Mike

[Jspeeddemon]

Yeah I think the guy that reapired my intercooler could do you one a lot cheaper than $1500. I will try and get his info for you. Man I am tickled that everything worked well for you with the box and carbs, I believe the tunnel ram is the key on those.

[IMPATIENT 1]

nice set-up!:devil: :devil:
guys , enlighten me on somethings. why does a blow thru set-up always seem to put out more power than a roots blower?? i understand the fuel isn't being heated up as much, but does the fuel cool the boost charge that much better? and do they rob less power to run and make the same amount of boost?:idea:

[N281PONY]

Nice numbers:) Put a little nitrous on it and watch it come alive. With a plate under each carb jetted with 75hp pills you will see about 300hp pickup. Its amazing what happens when you cool the air off.

[Warp Factor]

guys , enlighten me on somethings. why does a blow thru set-up always seem to put out more power than a roots blower?? i understand the fuel isn't being heated up as much, but does the fuel cool the boost charge that much better? and do they rob less power to run and make the same amount of boost?:idea:
Turbine style compressors typically heat the air less than a roots. Cooler air is more dense at the same boost, so it contains more oxygen, which lets you burn more fuel and make more power.
Cooler air also helps resist detonation, so more timing or boost can be used.
Blower drive losses are lower because more energy goes to compressing the air, and less is wasted as heat.

[IMPATIENT 1]

Turbine style compressors typically heat the air less than a roots. Cooler air is more dense at the same boost, so it contains more oxygen, which lets you burn more fuel and make more power.
Cooler air also helps resist detonation, so more timing or boost can be used.
Blower drive losses are lower because more energy goes to compressing the air, and less is wasted as heat.
cool , thanx for the info;) guess next season, i might need to get a blow thru system instead of upgrading from a 6-71 to a 8-71. sure be nice to scoot the bench back for more legroom in the tx-19:)
what's a good used complete blow thru system that'll put out 12lbs of boost and make over 900hp cost????anybody got 1? i haven't bolted my blower down and i could just as easily put a centri charger on it:D

[502 JET]

cool , thanx for the info;)
what's a good used complete blow thru system that'll put out 12lbs of boost and make over 900hp cost????anybody got 1? i haven't bolted my blower down and i could just as easily put a centri charger on it:D
I found my used Vortech on Ebay, I paid $1950. for it with the vortech single carb box and a pretty much complete set up. After selling off the single carb box and buying the 2-4 carb box and adding the cog drive and blow off valve I have around $2900. in the supercharger system.
Hey Warp Factor, nice explanation on the centrifugal supercharger.
I only built my engine this way to be different not for any other reason. Its not everyday you see a jet boat with a centrifugal blower, every body's seen one with a roots on it.

[IMPATIENT 1]

I found my used Vortech on Ebay, I paid $1950. for it with the vortech single carb box and a pretty much complete set up. After selling off the single carb box and buying the 2-4 carb box and adding the cog drive and blow off valve I have around $2900. in the supercharger system.
Hey Warp Factor, nice explanation on the centrifugal supercharger.
I only built my engine this way to be different not for any other reason. Its not everyday you see a jet boat with a centrifugal blower, every body's seen one with a roots on it.
i think its a really cool set-up.if i pulled up next to it, i'd pay more attention to it than a roots charged boat, i've got 1 of those:D seen plenty of em too.
so you could throw a nitrous plate under a single 950 holley in a carb box too huh????:idea: :D