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-   General Q & A (https://www.offshoreonly.com/forums/general-q-20/)
-   -   781 heads best mods (https://www.offshoreonly.com/forums/general-q/316268-781-heads-best-mods.html)

Budman II 08-05-2014 08:15 PM
Originally Posted by rev.ronnie (Post 4165930)
Honestly, a cylinder head set up like this benifet a greatly from higher compression (than stock) and a cam to compliment it. We have used 781 heads, with stock valve sizes and no porting and made 580+ hp with just 10.25:1 pistons and a generic Erson hydraulic flat tappet cam.

Would I put a fully reworked set of heads on a stone stock motor? Probably not worth the expense. Spending the money on pistons and a cam would net bigger results.
Ronnie, I assume that the 10.25 CR was being run on one of your street car engines - as you probably know, that high of a CR would not live for long with iron heads in a marine engine. Same with the 110* LSA - you would be relegated to running dry exhaust.

SB 08-05-2014 08:27 PM
Simple.

SPAM.

====================

You can run either or both...you just have to build for it and stay on top of it. Most biz's customers would not stay on top of it.

Quick2500 08-05-2014 08:28 PM
I'm running 10.08:1 with iron heads, no issues.... Static compression isn't a good number to base any assumptions on as the cam, rods, and stroke dictate what your actual running (dynamic) compression is.

rev.ronnie 08-05-2014 11:30 PM
Originally Posted by Budman II (Post 4166029)
Ronnie, I assume that the 10.25 CR was being run on one of your street car engines - as you probably know, that high of a CR would not live for long with iron heads in a marine engine. Same with the 110* LSA - you would be relegated to running dry exhaust.
10.25:1 and a 112° LSA are fine for marine applications. Marine engines run substantially cooler than their street counterparts. Detonation is not a problem on a properly tuned engine and premium fuel. Smaller bore, long stroke engines a not as picky as one would think. The domes are very small.

As mentioned, people can wreck anything. This is the main reason we don't do retail work. Dealing with other businesses and engine shops eliminates this risk.


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