Originally Posted by glassdave (Post 4208906)

same here, i had a pair of 525SC's for years and thought they were the shiz, ran pretty much flawless and turnkey for nearly three hundred hours. Was planing on building a pair of clones for the 38 Scarab but on chatting with the builder its prolly gonna be BM 250's (or similar) for a multitude of reasons. I had always thought a cooler and pulley would have been a good mod for the Donzi but see now that the 525SC's was a comfortably well thought out and built engine but not a whole lot of room to grow with that set up. I will say one thing i did like the whine they put out lol.

Originally Posted by HaxbySpeed (Post 4208868)

Yes. A bit of a hijack, but kind of related because it's where our blowers came from. The 2 stroke detroit's are incredibly durable engines, and very well engineered. They were built to be universal, the front can be the back, anything from one side will fit on the other, you can join them together, throughout the same engine series almost every part is interchangeable. Compound supercharging was common practice (turbos feeding roots blowers). They were never intended to be a long term use engine, but were so well built they just wouldn't die, and gathered a very strong following, only phased out many years later by more efficient, environmentally friendly engines. Speaking of engineering, modern performance gas engines have nothing on 1950's diesel tech. Overhead cams, shaft mounted roller rockers, piston oilers, bushed solid roller lifters, turbos, etc. Sounds Familiar huh?

Originally Posted by 4bus (Post 4208933)

Funny that you say that about the versatility. When I was young my uncle used to drive a DD yard truck at a busy shipping yard. I got to go with him a few times. I don';t know exactly how it did it, but to save time he would drive to one end in forward, then bump the engine somehow to make it run backwards! He would then drive to the other side in reverse, using the forward gears for more speed. He did it like clockwork. We would be going backwards in 4th gear at 30+ mph :D

Originally Posted by 4bus (Post 4208358)

Ya know....I want to, but.

I am not sure how much longer I will keep the boat. Right now it is very attractive to dealers and some buyers because the mods are internal, so it still appears to be stock. Stock improved I guess :D But there is no hiding an 871 blower. In it's current form Peir 57 would buy it outright at a good price if I wanted to get out and move to the mountains and live off the land hahah.

So...I go back and fourth. Bigger blowers, surface drives and paint. Or trade in for #6 fountain or OL. I just know once I get too deep I will prob own it for life.

Originally Posted by MichiMike (Post 4208926)

I know all too well how this turns into a slippery slope.Has been that way with everything I do.Now I have a giant hole in water I could toss money into.Need to be happy with My little 525's that merc carefully put together.

Originally Posted by glassdave (Post 4208906)

same here, i had a pair of 525SC's for years and thought they were the shiz, ran pretty much flawless and turnkey for nearly three hundred hours. Was planing on building a pair of clones for the 38 Scarab but on chatting with the builder its prolly gonna be BM 250's (or similar) for a multitude of reasons. I had always thought a cooler and pulley would have been a good mod for the Donzi but see now that the 525SC's was a comfortably well thought out and built engine but not a whole lot of room to grow with that set up. I will say one thing i did like the whine they put out lol.

Originally Posted by MILD THUNDER (Post 4209012)

Now, with the 420s making 6psi, i have hit 90mph on a 80 degree day.

Originally Posted by mike tkach (Post 4207797)

i agree,i just did a build that used a 10.71 and it suprised me,made more hp&torque than i expected.