steves86ta

iTrader: (5)

Hi all,

Long story short, i have a Jet Boat with a 5.3 in it. It runs very well for being a stock bottom end 5.3. Im pretty happy with it. Finally got all of my little issues sorted out, and the thing is running hard and very well.
Currently it is an early 5.3 (24x i dont know the year)
ARP 2000 Rod bolts
Untouched bottom end other than the rod bolts.
BTR stage 4 NA LS1/LS2 cam
243 heads cut .030"
BTR valvetrain including BTR trunions
Victor JR with 850 Demon carb

It runs well, actually better than most people expected. For those that know jet boats, i spin a BC impeller 5300 on motor 6300 on a 150 shot.

With that said... It's winter, i just got a pretty substantial raise, and a decent Christmas bonus. My 5.3 has an unknown amount of miles on it (should have seen the amount of sludge in it) and i beat the living snot out of it. Sounds like a NASCAR and just in general is abused every time out.

So... Before it lets go and leaves me stranded somewhere. (especially now im spraying it) I am planning on building another engine.

Being in southern california, it is very hard to find 6.0 blocks. And when you find them, they are insanely priced when all you really want is a bare block.

However, 4.8/5.3's are easily attainable. Being in a boat, heat is not an issue, so i prefer the extra strength of the iron block.

I want something stupid... i want to be able to line up with most of the big blocks that i come up against and i want to beat them with my "small block"

In all honesty, i already beat a lot of the "big block" guys as it is. And i havent ran anyone with the bottle yet.

So now that you know the background, lets get to the reason for this post. Im coming to the people here that have more experience/knowledge than i do. I have some decent ideas, but not a lot of LS experience. (other than my 5.3). Im sticking with a ls based build because the look on peoples faces when they see that its a "small block" they stand there in disbelief.

I want to build a 383, the reason i want a 383 is because i want to stick with a 4.8/5.3 block. Drive-ability is not an issue, weight is not an issue, idle is not an issue (my btr stage 4 idles right at 1k now), Fuel requirements are not an issue.

Im open to suggestions, recommendations, and conversation about picking components for this next build. My goal is somewhere around the 650-700hp mark at the flywheel. Then bolting a 250 (maybe more) shot ontop of that. I would like peak power to be in the 6500 rpm range, lower is better but really dont want to have to swing any higher than that. I want to stick N/A with nitrous. No Boost

Here's what im thinking please let me know if i am on the right track. Or if there are other things you would do differently.

4.8/5.3 block either a core or one from Summit (300 bucks)
CP Carrillo bullet pistons 3.905 bore, 1.105 comp distance, +1.3cc volume
Lunati Voodoo 4" stroker forged crank
K1 6.125" H beam rods
Cam, will the BTR Stage 4 meet my goals? If not, what would you suggest?
Heads, Open for suggestions, looking at the AFR230's, Having AI do their magic to my 243's? Again, open to suggestions
All ARP hardware, main studs/head studs
NOS Cheater plate system

Again, i'm open to suggestions. Would like to stick with the carrillo pistons, ive had good luck with them in the past. Dont mind being north of 11.5:1 compression.

thank you for your time and suggestions

svede1212

iTrader: (3)

Positive cc pistons are going to get you a pretty high CR (up over 12) unless you have really big chamber heads. The extra stoke increases compression with everything else the same.

I would talk to whoever specs your cam and heads so you get stuff that works together. I already had -8cc pistons with my stroker so Tony Mamo spec'd his head chambers to 58cc and sized the cam so it would give me what I needed. It's how it all works together Being a boat run at high rpm and prone to spiking I'd spend some attention to making a very light valve train to prevent valve float

steves86ta

iTrader: (5)

I checked out Mamo motorsports website. Not much info there. Is there a way to get ahold of him?

Thanks
Steve

98_WS6_M6

iTrader: (18)

If he didn't already contact you his email is: mamomotorsports@yahoo.com
He's on this site too.

Good luck with the build! Looks like a lot of fun!

steves86ta

iTrader: (5)

Thank you, i sent him an email

Tony @ Mamo Motorsports

Busy day today guys....

Steve I did get your email

Thought I would address the fact your goals may border on impossible if your committed to keeping RPM down. While 700 may be possible with a 383 it is certainly an extremely stout goal that will take a solid roller and more RPM to get there (low 7000's in all likelihood).

A motor can only generate a fixed amount of TQ normally aspirated.....HP on the other hand is directly related to airflow and RPM and is much more of a big wild card. That's why small engines need alot of RPM to generate big power....their torque limited so the only way it can happen is with RPM.

If you make 1.4 TQ per cube your doing pretty good.....really good actually. And an engine typically sees 90% of its peak TQ output at peak power as the TQ curve rolls over (these are guidelines but usually very close)

So a good 383 might make 535 ft/lbs or so at the flywheel. If you take 90% of that figure for the amount of TQ likely produced at peak power you get 483 ft/lbs.

Take 483 ft/lbs X 7000 and divide by 5252 and you get 643 HP but still need 7K to make that happen and that means you built an engine that has enough camshaft, cylinder head, induction, etc. to make peak power at 7000 RPM....a combo that in a car you would likely shift at 75-7600 RPM's.

A similar combo that peaked at the OP's target of 6500 would only make about 600 HP which is still no slouch for a 383 CID engine (closing on 1.6 HP per cube).

So....if we are sticking with a 383 and sticking with a target redline of 6500, we see that its basically mathematically impossible to approach 700 HP at that low an RPM. We need more cubes (adding to the TQ multiplier).....or more RPM (adding naturally to the RPM multiplier).

Hope you guys are following this....its cool stuff as some people think an engine can produce any results if you throw enough money at it and that is absolutely not the case. Especially if we are speaking of a N/A application. With boost, if you pour it on hard enough and its an efficient system your potential output gets exaggerated a great deal. Thats why turbo's kick azz with the right set-up. Wasted energy converted into boost is awesome!



Cheers,
Tony

steves86ta

iTrader: (5)

Thank you very much for your explanation. Now I'm understanding that 600 is much more attainable with my rpm goal.

Couple of reasons I was shooting for the 6500 mark,

1. On the bottle I'm going to see an easy 1000-2000 rpm increase. Depending on the shot. For example on a weak 150 shot I get about 1k rpm with my 5.3.

2. The size of impeller I need to spin 7k plus will make my cruise rpm insane. With my current impeller I cruise in the 3500 range. Really don't want swing 4500 all damn day long of you know what I mean

However, it seems that a 600 hp 383 is more attainable, and then the bottle on top of that puts me in the 7500 range or so.

Easily reaching 800 plus im guessing?

What were your ideas for cam/heads? Think my BTR stage 4 has enough to make it?

Thanks
steve

steves86ta

iTrader: (5)

Don't know if this helps with suggestions at all. But here'sa chart of hp to iimpeller size to rpm

currently I'mrunning a "BC" impeller. You can see as rpm ccomes up it really takes more hp to spin more rpm . Again these are just guidelines. But are generally close enough for bench racing.

Tuskyz28

Even with the best of best heads and intake on market I don't see 700 horse at the crank happening. A realistic number is 1.55 hp per cube..... even some larger 400 plus cube motor struggles to make 650 horse at the crank.

Now if you talking a high rise intake, a solid roller cam, high compression, and spin the motor 7500 plus RPM it's a different story.

Martin Smallwood

iTrader: (2)

I think you'd do better with a C impeller if 600hp is the goal and 6500rpm your RPM ceiling.

steves86ta

iTrader: (5)

I've thought about trying out a C impeller... But remember

My Ceiling is 6500 on motor. Then nitrous ontop of that

Currently with my 5.3 i spin about 6300 or so on a 150 shot with a BC impeller.

The downfall to going to a C impeller is my cruise RPM woudl be 4k or maybe even higher. Right now its in the 3500 range at about 40mph.

Lots to think about here. The conclusion i have drawn is this is hard to dial in. By that i mean that these motors make stupid amounts of power uptop. But not down low.

I think the main problem using a LS in this kind of application is that you hit a wall. And what i mean by that is, that your impeller is always the same size, always taking the same big bite of water. Just depending on rpm, it moves more water and consequently more load.

Take for example... my 5.3...

At Wide open with a BC impeller i spin about 5200-5400 rpm (depending on where i am altitude wise)

According to the chart, thats around the 360hp mark. It cant spin higher, bceause at that RPM it doesnt make enough horsepower/torque to spin any higher. However spraying just a 150 shot (63 jet on a cheater plate) I pull clean up to around 6200-6400. (instantly i might add)

And again looking at the chart im in the 620-650 range. Thats nearly a 300 hp gain. I am not spraying enough nitrous for a 300 hp shot. But what i am doing, is allowing the big cam and heads (not that big, but still) breathe and the little engine really start to make more power.

I hope that makes sense? I think the best thing to do atleast in my opinion is to put together the engine i want to. Build it however i build it, then dyno it and choose an impeller cut.

But it really needs to make some decent power down low to beable to get up into its powerband, again if that makes sense?

Martin Smallwood

iTrader: (2)

Forgot about the nitrous.

I agree that the best thing to do is put the engine together, dyno it and then choose the right impeller.