berns29scarab

I have a 98 29ft scarab. tryin to find out if there are any inexpensive upgrades available for the 350 mpi's. K&N's, cold air intake's, ECU upgrades etc...its currently turning 47-4750 rpm's WOT with 23p counter rotating mirage pluses. just over 70mph on a handheld garmin. it has the cheap version of the quick n quiet (no controllable)plus it has external mufflers of some sort.

MACDAD260

I don't think the words "inexpensive" and "upgrades" belong in the same sentence. To make more power you need to get more fuel and more air into the cylinders. A K&N might be good for a little but, beyond that just make sure your timing is correct, your plugs and wires are good. If it checks out your next step will cost some serious cash. Heads, cam, ECU reprogram, bigger injectors, headers, it never ends. Good luck. BTW, 70 mph on a 29 with small blocks doesn't sound too bad.

tssteph

That is a good speed. I have the same boat. 69.4 is the best I have ever had on a GPS. Props are being done by Darin at Houston right now. If you find some other upgrades let me know. I would be interested. My only thought is a reprogram of the computers by someone like arizona speed and marine. I did put stainless marine headers on mine and eliminated the cheap quick and quiet. Same performance, just much better sound.

The elevation difference might account for some of the speed difference between yours and mine, or current/wind or amount of fuel. I have never ran mine on empty, my 69.4 was with 3/4 fuel and full gear.

If you run the numbers on 23 pitch props with 0% slip it won't run 70+ mph at 4750 rpm, so something might be a little off.

NJDave

I agree. At just 10% slip you get 62.1 mph and only 10% slip is imposable on a non step vee bottom boat. I would say that boat on a perfect day on salt water will run 60 for real. Sorry just being honest not trying to call him a liar.

tomcat

There is a section of the high performance market that caters to the need for relatively cheap, easy to install parts. The trouble is they don't usually increase performance. How many guys on this site have installed new flame arrestors, high energy ignition, new exhaust etc. and seen little to no improvements. The truth is most engines can't utilize the potential of those easy to bolt on parts until you change some not so easy and not so cheap hard engine parts like heads and cams, or cranks and pistons. It takes a lot of extra HP to make an impression in a boat. What you need is an extra 100 ft-lbs!

Doesn't come cheap though. Welcome to the club!

berns29scarab

the tachs are off by 250 rpm's....at there reading of 4750...i'm actually running 5000 rpm's at wide open throttle. put meters on the other day and ran her again...69.6 at WOT of 5000 rpm's into a 10-12 mph head wind and lost about 2 mph runnin with the tail wind....need a bigger prop

Slick02

Curious to see the answers to this question, I've got an 02 formula 292 with twin 350 mpi's and with 28 pitch 4blades at 4900 I'm running about 68 to 69 on a good day with half a load of fuel, and the formula is heavier than the scarab.

TxHawk

The 29 Scarabs that i have seen have a really low x dimension that slows them down a lot. We recently built a 29 Scarab at Derebery Performance with a single 810hp Blown Engine. The boat only picked up 15 mph from the stock 502. It runs 75-80 now. The 29 Scarab needs ALOT of power to be fast. I dont think 20-30 hp ungrades and going to help. Anyone know what the 29"s with the 525SC's and Blackhawks were running?

articfriends

Sorry bern,i have to agree with everyone else here,if you are getting 70 mph thats pretty decent,without blowers,turbos,more compression, bigger engines,radical exhaust or something major your not going to see more than 1 or 2 mph max gain. Spending 1200 $ reprograming your ecu's and putting k/n filters and billet air inlets will probably yield you 50 rpm's and 1 mph,sorta like feeding a tictac to a whale. Wax your bottom hull real well and try a few set of borrowed props,optimize your base ignition timing and check your tuneup,that will probably yield you the most (still 1-2 mph),Good luck,Smitty

tssteph

Our boats are identical, 69.4 at 4900 rpm. I had my props done by Darin, tested on sunday and saw a hair 70 mph GPS with four people and full of fuel. I have not tested with a light load.

Your speed and rpm makes more sense now.

I think prochargers are the way to go.