easy horsepower ideas???
 

After spending many hours searching and reviewing threads on hp gains, I thought I'd ask the question out loud. What is going to be the best bang(s) for my buck??
I would like to keep the bottom ends together as they are fresh (50 hrs) but since the motors are out of the boat for some minor oil drips I just can't help myself, I'd like to move up to spinning a 25 pitch prop from a 23 plus. This is what I'm starting with;
2 461 ci 4 bolt steel crank, dimple rods,

freshened G.M HiPo iron, rect. port heads 2.25 intake, 1.88 inconnel exhaust

cam is ultradyne 288-296-114 hydraulic flat tappet

weind team'G' intake , 850 holley double pumper, t-bolt ign,

Imco power flow exhaust

This combo is making 485 hp at 5300, and 486 ft/lbs at 4500

I'd like to see top end around 5000-5100 rpm, this is pushing a 40' 12,000+ lb boat.
I was thinking about the bore notching, hyd. roller cam change, head work/change. I am looking to spend about $2000 total--so changing the heads is a stretch. I was thinking about whipples-- after much debate I think i'll make do with this for one more year.

Anyone have any ideas or see something that i missed:confused:

Hello, del sol,
You didn't say if your heads are GM or aftermarket. The best head I have used in this type application is Merlin OVAL PORT. They are not that expensive and your valves and hardware will work in them. Just pocket port them and check port match. You will be better off with a oval port intake as well, but the square port will work.
The hydraulic roller is a super idea and would be my first change. Be sure you have the correct valve springs and consult with a MARINE camshaft expert at the cam grinder of your choice-don't just talk to the guy who answers the phone!!
I have built several engines similar to yours and used Merlin heads with single plane intakes and hydraulic roller cams. No one ever changed the heads to ANY other type-square port, iron or aluminum of any brand on these and made as much power.
A lot of people seem to think you must have aluminum BIG ports to run, but the right size is what works best.
We run the Crane 139741 a lot-great in a motor like this!!
PM me if I can help!




11:D :eureka:

blown1500
Thanx for the reply, I changed the head descr. as for the merlin oval ports, are the alum. or iron? and can you get them in bare heads? The other thing i've noticed is that it seems that i'm running pretty large numbers on my intake/exhaust compared to alot of people lift int. 550, exh. 575. It does give it a great sound out of those straight pipes at an idle and at throttle though:D

With only $2k to spend (total) on two engines. Hmm, the only thing I would be able to suggest is head porting and concentrate on the exhaust side.
Add a competition 3 angle valve job and there's $2k easily.

I agree with 1500 that the oval ports are a better selection for your cubes. If you're able to find a couple sets of ovals that are less than 300 cc's intake runners, that in my opinion, would be the way to go. Especially if you found a set with around 110cc combustion chambers. That would increase your comp ratio to around 9.5 assuming you have the stock 8.75 compression now.

By doing the above your hp wont jump by a huge amount but your torque will.

DAVE

You need TORQUE mon!!!
 

del, with a boat weighing in at 12,000lbs you're going to need as much torque to get that 12,000 pound mass moving! First, with all due respect I would use some DUAL PLANE aluminum hi-rise intake manifolds....not an open plane intake as you already have. My cousin's 461's were bore notched, has hydraulic flat tappet 218*/226* camshafts on 110* lobe seps with a lift of only about .520", with 8.6 comp ratio, some poor and very CRUDE GM casting oval port semi open chambered heads that he had pocket ported and had 2.19"/1.85" stainless steel valves installed, 800cfm Holley carbs and DUAL PLANE aluminum hi-rise intake manifolds on it and on the dyno it made 461hp @5100rpm and 510 foot pounds of torque from 3400rpm to 4900rpm---VERY FLAT which is excellent! These were done with tubular dyno headers but he is using GIL exhausts with bone dry tailpipes. He will probably lose about 20hp or so going from the dyno headers to the GILS. This combination is STILL extremely respectable for the kind of parts he has in it!

What kind of exhaust manifolds are you running? The oval port Merlins would be a good way to go as blown1500 and Dave F have suggested OR you could send your current rectangle port heads to JimV and have him install wedges within the intake runners and really see a healthy gain. You'll have to weigh the cost differences from the Merlin oval ports with some bowl porting to the wedge mods and decide from there. I also think a hyd roller cam would be a good move as the others have suggested. Hydraulic roller cams, lifters and new springs are going to use up half of the $2000 you're willing to spend though, another $500 for the dual plane intakes. Also, you might consider a bore notch job that is worth the cheapest 30 horsepower/torque increase you'll ever see. Anyway, you won't have much $$$ left over to buy Merlin oval port heads with bowl porting and valves and springs installed or even have wedges insatalled. If you are doing some mods for next year then you're going to have to decide what mods to do this time around that will be cost effective-------believe me, it can be a very tough spot to be in when you're trying to spend your money as wisely as you can. However, there is sometimes just no way around it though. But for sure, I would switch from single plane intakes to a dual plane and do a bore notch job and if you're going to be upgrading to a supercharger in the future, you might consider having the hydraulic roller cam (the one you're going to get this time) be compatible with the super charger set-up as well. Usually this will involve keeping the cam on a 114* lobe seperation. That way when and if you do go to a super charger in the future (as you were thinking about) then you won't have to spend more $$$ money for a pair of new cams that will cost you $600. One thing I am quite sure of though is that with a 12,000 pound boat---you NEED TORQUE mon!!! :)

Save your money, $1000 per engine is not going to get you any noticable performance on the water with over your current setup IMO, try some 25 labbed props probably make a bigger dif altho 12000 lb maybe to much of a compromise on the mid range perf

Ursus,

Those are pretty much what my thoughts are. With a 12,000 pound boat I'm quite sure he spends most of his time cruising and he will need and benefit from a ample amount of torque in the mid RPM range. Plus, if he decides to hammer it he will see much better throttle response from the torque as well.

Del sol, dual plane intake, hyd roller cams, bore notch= TORQUE! :D
With these mods you'll be able to stay right around the $2000 range of your budget. :)

My thinking is he is already making 485 hp and has decent exhaust,intake manifold cam package,heads, the gains to be had spending only 1k will be small on the dyno and non existant on the water, $2k is what you spend on exhaust system, intake manifold, bigger valves etc getting from 415 to 475 hp and he is already there

ursus, I am talking more about Torque than I am horsepower, but he will gain Horsepower as well. Would he not especially benefit by at least installing dual plane intakes and a hydraulic roller cam? Wouldn't it shift his torque curve down to a lower, more usable RPM/cruising range? With a boat that weight (12,000lbs), I would say he probably has to cruise at about (rough guess here) 3500-4000rpm minimum to keep the boat on top of the water and from acting too sluggish (it's just a guess). Again, what I am talking about is Torque and Throttle Response---although he would see some Horsepower gains from these mods as well.

BTW, I am not trying to upstage anyone here. I also, don't want to make myself look like I don't know what I am talking about here either. It also comes down to what the guy wants to do as well, but if I am wrong (I certainly have been before) then would some of you other experienced comrad boat and engine fellers and dudes step in and tell me where I am at fault or where my theory is wrong on this please? Or is ol' ursus and I trying to split hars, or what? :crazy: Thanks :)

Mark/KAAMA

I am not trying to upstage, trample toes or split hairs and was not questioning whether the mods you suggested would do what you said they would, they would. My thinking is out on the water it will only make a hair of difference and in a blind driving test (well maybe not blind :D :D :D ) you would be hard pressed to see the difference. It depends what you want I guess, my opinion was from where he is, which is 485 hp and he already has aftermkt upgraded exhaust,intake,carb and cam he was better off putting the $2k in the whipple account but thats just my opinion.

First let me start by saying thanx for the responses! Kaama you are right on with the 3800-4100 rpm that gives me a cruise of about 40-42 mph depending on conditions. At 34-3500 where I would like to be it falls of to 34-35 mph. With the 25 pitch mirage, it was just a little big --max rpm was 4300@ 57 mph, but the minute i dropped the rpm down to 3500 it lost the torque and wasn't real nice--throttle setting was not much different. I'm thinking if i could be around that magic 500-525 mark @ the prop I could spin the 25's and cruise at 3500 around the 40-42 mark.

The reason I said 1000 per engine is because I know that it'll be double that by the time i'm done, then I ahve to factor 1.63 to get it to my ****ty currency:eek: .

Besides I keep looking at the whipples and thinking I should just do that and leave the rest as is;)

Ursus--- You nailed me with the 'driving blind'

I would also try a set of 24 Bravo ones see what happens,I wished I had some but at this time of the year we dont ,check back with us more towards summer and we might have a set you can try,it cant hurt.

Since motors the motors are already out, I would think about 4.25 stoker kits. Shop around (ebay, speed shops, machine shops) and I think you could find them for $1500 or so. Spend a little extra and get 6.835 H-beam rods and pistons so you will not have to do block notching (worked great on my motor plenty of room). You already ave a .060 overbore at 461 so a quick hone job is inexpensive compared to a bore job. Longer stroke will help with your midrange and faster piston speed will take advantage of your rec. port heads. Notch the bore to help with 2.25 valve. Get flat top pistons and check compression ratio very carefully (adjust with head gasket thickness). Try to get a balanced kit. Sell your exsiting bottom ends to offset the cost. Think about oil pan upgrades if you have any money left.

Just my 2 cents of course. But you need max torque with a heavy boat and this is great upgrade for a 454 based block.

Dual plane intakes will improve your low end considerably and help all through your rpm range. They are only $150 or so an would be money well spent. The Whipples are the ultimate, but if I were on a tight budget, intakes and cams are where I would spend the money. Your heads won't show any improvement in the water with port or valve size increases. Your heads are too big now.
If I were in your position, I would do cams and intakes, maybe carb changes and put anything left in the Whipple account.
If you need good prices, cam advice, or anything else I can do, pm your number or call me at 704-574-4020.
Have a great day!!!

As KAAMA said installing the wedges will do the job. The intake will have to be welded to match the raised floor of the port. Your intake will work in this situation, (money saved). With additional intake porting and exhaust work 35-40 hp and a butt load of torque is not out of the question, more if you are overcammed. Remember 40hp @ 3500 rpm is 60 ft lbs. The bore notches help but keep in mind that you will loose a couple of cc's between that and the much needed chamber work. Check out my home page(it's getting back together) to see a cross section of a port that's been wedged. It's a merlin head in the picture, but the same concept. The head and intake mods will stay in your $1,000.00 range. All this is nothing new, I have been doing it for years. Good luck

Dual plane manifold may do what you want but it may not. Dual planes do not outperform single planes upto 5500 rpm, in fact they are about equal around 3500, below the dual plane is better above the single plane is better so its a trade off, you have to decide what you want. Heres a desk top dyno of the engine with all things equal except the manifold type

Hey ursus:

How did you post that graph off Desktop Dyno? Whereabouts are you on Lake Huron?

use shift+print screen this copies the whole screen to the clip board, paste it into your fav editor to crop resize etc

Your combo (both engine specs and boat weight) sounds a lot like mine (Formula 402). Best bang for the buck I found was going to 4 blade Bravo 1 props. Got me about 7-8 mph in cruise, no change to mayble -1 at top end.

-Greg

GregP -- wow that's huge increase! I had tried a 4-blade mirage first, I'll have to dig out the #'s on cruise speed, I know that top end was only about 56.

Thanx to everyone for responding, some great ideas here as i expected there would be.