tomcat

We all want more HP for less money. But there's no free lunch. What is the $/HP ratio for typical upgrades?

Case #1: You have a 454 - 330 HP.

Phase I - 400 HP

You upgrade the carb, intake, cam, valve train, ignition, ported heads and good exhaust. You spend $4000 and add 70 HP. Ratio is $57/HP.

Phase II - 500 HP

You need to add forged crank, rods, pistons, go to hydraulic roller and aluminum heads. You spend another $5000 and gain another 100 HP. Ratio is $50/HP. If you do both phases at once, ratio is $53/HP

Case #2: You have a 502 Magnum - 415 HP with hydraulic roller cam.

Phase I - 500 HP

You already have the forged bottom end parts so you spend your money on carb, intake, cam, valvetrain and exhaust. Basically you are creating an HP500. You spend $4000 and add 85 HP. Ratio is $47/HP.

Phase II - 650 HP

You buy the rotating assembly to build a 540. More money is spent on the carb, ignition, cam and valvetrain. You add ported aluminum heads to get the required airflow. You spend another $7500 but you add another 150 HP. Ratio is $50/HP.

Case #3: You have an HP500 carb engine.

Phase I - 700 HP (5psi)

You already have an engine with lots of good parts. You decide to supercharge. You don't cut any corners. Better exhaust valves are put in the heads and the best head gaskets are used with the best head bolts. While the heads are off you have the exhaust pocket ported. You install a complete new fuel system sized for 1000 HP. You purchase a properly modified blowthrough carb. You buy a supercharger system with a large blower and large intercooler. You spend $10,000 and gain 200 HP. Ratio is $50/HP.

Phase II - 800 HP (7psi)

You stop fooling around and put a smaller pulley on the blower. You spend $100 for the pulley and the shorter belt that goes with it. RATIO IS $1/HP. . Of course the reason for doing everything right in Phase I was because you intended to use 7 psi anyway. Overall ratio is $33/HP. This is way they say blowers give the biggest bang for the buck, as long as you are able to swing the larger budget all at once.

Of course there are other combinations possible and my estimates may be a bit off. What has your experience been with $/HP??? Do you think $50/HP is a decent approximation for most upgrades?

articfriends

iTrader: (1)

Tomcat,it always seems like a guy could put a price on hp but a better way to look at the real cost would be per mph gain. The best example i seen was the article in power boat magazine where teague turned a guys 502 powered 38 ft fountain(a boat i would love to have) into a 80-83 mph boat. His final bill (if i remember correctly) was 53 thousand dollars. It seemed like ALOT of money but when you looked at the breakdown including outdrives,props,r&r labor nothing was outrageous,it just ADDS UP!Guys looking at adding 200 hp to their boat for ,say, 10,000 $ should keep in mind the other parts they will also need (if there boat doesn't already have it) like-upgraded outdrives,full hyd steering,numerous props,aftermarket ignition systems,bigger oil coolers,motor mounts,exhaust systems,fuel systems,drive couplers etc. Most boats that have 454/502 mags are already at the limit of there supporting equipment and the poor guy who decides he wants to pick up 15-20 mph and doesn't look at the big picture ends up buying these other parts one at a time while his boat sits broken in the middle of prime season while all his buddies are out cruising around in there stock powered boats!!!Now,don't get me wrong,i don't want to discourage anyone from hopping up there boat, i just want some of these guys to realize what there speed is going to really end up costing them !!

bpine

I think of it this way.

Heads, CMI Exhaust, a little money for Bob Teauges racing fund, Carbs, A little more money for Bob Teauges racing fund, Blower, More money for Bob, Props, ---------total cost $15,000.00


I beat my Buddy this weekend by 5 MPH, Bragging rights 24 hours a day, the smile on my face--------PRICLESS

Dave M

Interesting post. Tomcat's math makes perfect sense. However, I think there needs to be reliability and longevity variables in there too. Everytime I think of engine mods the reliability thing enters my mind. When I finally decide on a power upgrade I think I am going to just buy another engine and keep my stock mercruiser engine as a spare. Boating season is too short to be having much downtime.

Dave M.

Airpacker

Tom, you really need to just go buy a new boat and stop thinking so much

Now, lets see, 500efi plus new aluminum heads, roller rockers, lifters, springs, keepers, retainers, gaskets,adjustable fuel pressure regulater, machine shop bill on new heads = $5000.00(jobber net cost, not m.s.r.p.) to net 570 hp = $71.428 per hp gain. If i had to pay for re and re, disassembly, reassembly and set up I would think you could add another $2500 to the equasion so $7500/70hp=$107.142/hp gain= ouch.

tomcat

Good points all. Safety, reliability and a keeping your stock engine as a spare will all change the math. If you include the cost of hydraulic steering and better drives on the higher HP upgrades, your total budget could easily double.

Talking about keeping your stock engine makes me think about engine swapping as opposed to upgrading. It sounds like less trouble but what is the $/HP ratio?

Case #4: You have a 454 Magnum carb engine.

Option 1 - Remove the stock engine and sell it for $3000. Buy a 500 HP crate engine for $10,500. Add CMI headers for $2500. You have spent the difference of $10,000 to gain 135 HP. Ratio of $74/HP.

Option 2 - Same as above but keep the stock engine. Ratio is now $96/HP, but you have a backup engine.

So buying a crate engine and keeping the stock one as a spare costs almost doubles the typical $50/HP ratio. Good insurance but most of us are "uninsured".

Cignificant

I have a 55hp Johnson I bought off ebay for $800 = $14.55 per hp
I have a 5hp that someone gave me (he thought it was broke) = $0 per hp

Now if I could just get my BBC into these price ranges...

Cord

iTrader: (2)

Ok, I was waiting for the plug. You have 454mag, 502efi, hp500, etc. and add a supercharger being sure to use the R-Tech intercooler...

MAG502NUM

Tomcat- Lets do a different twist on Phase 2/ Case 1....Retain the mpi induction and programming, add a MAP/runner friendly cam...somthing like 226/230 114 cl crane lobes...$450cam/springs [I'm going cheap and reusing my lifters to look good here, Tom] Adj. Fuel pressure regulator,$70...and some free flowing exhaust manifolds,$1500. Let's see, 70-75hp for $2020....or about $28-29/hp...Just prop the boat close to the 5050rpm rev limiter! Case 2 adds 30hp and 200rpms for an additional $900....shorten lower intake runners, remove rev limiter, some mild head work: DIY pocket port, 2.25" valves, bump compression to 9:1......still around $29-$30/hp.
I'm being a little optimistic here as I'm mostly having fun...guess it would be nice to have some roller rockers along with some new lifters for that cam....but its still going to be cheaper than the carb conversion if your only after 500hp, after that, the MPI build up quickly loses its price advantage.
I'll have to agree with your, um, agenda here though, I think for big horsepower, supercharging offers the best bang and drivability for the buck.

BadDog

Case 1 (Kid boat 1)
9.9 Tohatsu, changed jets, changed advance mechanism and wind it up. New HP 15. 5.1 HP for 22 dollars. $4.31/HP

Case 2 (Kid boat 2)
Buy new boat for kids, 5k with 225 HP $22/HP

Case 3 ( My boat )
502 existing
add headers, do heads, cam, lifters, blower, drive etc.
200 hp for 10K, $50/HP should have bought another kid boat.

Going the wrong ($) way each step.