That explanation I can understand...thank you.

Ok, im with phragle or maybe even farther behind , it seems every time I see cam specs I see different sets of numbers. Some make sense some not! How does one figure what each means , and the end result?

While kind of irrelevant to your builds here, a buddy of mine just used a 525EFI merc cam, in his 502 build with 250 Blower shop blower (non intercooled) 7psi of boost. He switched from stock HP500 setups, to Dart Pro 1 heads, and 525EFI cam. These engines will be going in a 33AVS scarab. With the prior setup, stock HP500's, 250 blowers, single dominator, the boat ran low 90's. It will be interesting to see what he gains from the head/cam swap. That cam peaked at 5800 in his 502 with the blower. I basically run the same cam in my 468's, and at 6200, it was about done. Also with dart heads and 7psi. I'd imagine it to peak quite a bit lower in N/A restricted intake setup.

Like everything, you need to learn basics first. Go in your faorite search engine and type in Camshaft Basics, and you'll find many rag mag and other articles on this. Don't let your brain get to in depth with it for a bit. You just want to learn the basics. Have fun !

Still somewhat relevant though to me since I own a 33scarab avs! I wonder how much hp he was making with the 7 psi blown 502's? My Scarab runs 84 gps and has seen 85 gps running light with stock hp 500 efi's with exception I reprogrammed them to hit rev limiter 200 rpms higher than stock so it could spin the 30 labbed props high enough to get in mid 80's and added a couple degrees timing from 4200 to 4800 where it was lazy feeling (hard to ever feel like boat isnt a dud after driving my 272 with 1000+ hp single). Will be interesting to hear what it runs when its done! I am still in planning stages with my 33 , prob NOT pulling motors out this year since boating season is really only 3 months away now (old boat has to sell before I get too carried away modding new boat!). I havent made firm plans as to how I'm repowering the scarab but its sloooow at 85 mph! Bought a extra 500efi intake to test on dyno meanwhile, still have a pair of m-3sc prochargers, i have a pair of Max machine worx drives with all their good shafts and towers, I have 2 pairs of AFR/Mamo cnc'd heads ready to bolt on something, a dart big m block/540 short block with just dyno time, a spare merlin block etc. The boat glides thru water like a catamaran at speed so leaning against putting blower motors in it. 780 hp should put your friends boat well over 100 mph, Smitty

Sounds about right. I know another friend of mine has 100 percent bone stock HP500's in his 33AVS. Boat runs 82ish. They are good boats and do well in the rough for their size.

Im not 100 percent on this, but I want to say before the heads and cam swap, the engines made somewhere in the 650hp range. Same dyno. Boat is stock as far as setup goes. Stock standard bravos, etc. I think he saw 92-93 with that setup.

Gary's 33 before the upgrade is in my video. Sweet boat and it took me alot to pass him in my Outlaw. Mild Thunders running good in this video also! Good times!

Looking forward to hearing how your upgrades go next year Smitty!

http://youtu.be/-FEFZiSMsFg

I'm pretty sure it's this stuff printed on sophisticated paper. My daughter makes it for me! Back in the old says I'm told they used gold instead of paper. Pretty neat stuff!

I have heard there are a few having very limited success with hi quality laser printers, However I am lead to believe that failures in that route can be rather catastrophic..

Bigger is better so it seems. "Restriction" can mean no big deal or really big deal depending on your engine. Once again Smitty has provided us with sound real world testing.
For those who don't have nor ever had a 454/502 Mag EFI/MPI here are a few pictures to illustrate what is being discussed as the restriction. The 454/502 Mag EFI/MPI's
have a two butterfly two stage throttle body as opposed to the HP525's mono blade.

Stock K & N - This is what I have on my stock 502 MPI. Note the aluminum adapter. I added this air filter/FA to keep bugs and those damn puff ball seeds(cottonwoods?) out of my engine.
My stock FA would be full after a week or two of running. During testing I lost a max of 9 RPM's using the stock K & N. I did find that when at full throttle(engine off) my two butterflies were
not parallel. The primary was past open and the secondary was not fully open. There is no way to adjust them. Smitty did you notice this and/or find a solution?


Hardin Marine SS - Note the aluminum adapter here compared to the stock K & N. Keeping the air flow separate for the two butterflies may help flow. I will leave speculation to the guys
with dyno's or Scott(CFM, SB) who marketed a similar device as to how much.


Compare HP525 to New Hardin - So if Smitty's 65mm bore throttle body works well how about 75mm bores? Heck why not make an adapter and use an HP525 style monoblade? It sure would
be nice to see a chart to know at what HP level you will need a throttle body of X size in order to have no restriction.


New Hardin HP525 - Sweet looking piece and probably flows like no other but at $599 it is not for the faint of heart.


I purchased my K & N from the old Dana Marine. They now carry a Gaffrig FA that looks really neat. There have been many aftermarket air filters/FA's sold by several companies over the
years. If you have a stock engine or a slightly modified one I would not be too concerned with the restriction problem. If your HP is over 450 then a different air filter/FA and throttle body
should be considered in your budget.