Well, everything is coming together with the BTO. Some bad luck with the motor has turned into some good luck. I am re-thinking my compression ratio numbers, as I am having to buy new pistons for the motor. Anyone who has done a project knows that whatever you have is never good enough. I had set up the motor to have a 9.32 compression ratio. This motor is a cast Iron 2 bolt block with Iron 119cc Oval ports which have been mildly ported and polished by myself with a clean up via the local motor shop. The motor will have Lightening Headers, with a Scat forged steel crank, Eagle H-Beam Rods courtesy of Flat Broke, a Comp Cams Extreme Marine Cam (can give numbers if necessary), a Weiand X-elerator manifold with a Holley 850 . I do not want to cross the 600 hp marker because it is a 2 bolt, but I do want to get close to it. Any suggestions, can I go for 10.0 to 1 or should I stay at 9.32, as I know as is, it will be a sound motor. Thanks for your time...Joe
PS... I do not want to turn this block into a 4 bolt at this time, I will be looking at new blocks after next Summer.
I know you said that you don't want to go with a 4 bolt block just yet but if your planning on going that route at all now is the time. Get a set of splayed main caps from summit, hav them fitted to the block and go like a sum-bitch. 600 hp is a weak rating for splayed caps.
something to think about, when have you ever heard of someone pulling a crank out of a two bolt main block? I have been running a bbc with hp some where around 800 for three years now in a flattie and my crank has not pulled out. In my opion the crank doesn't take the initial shock like on a car and I have had both and the question is have I just been lucky? Three years of testing now and its still in there and oil psi still the same filter is still looking good on the inside from after everytime I get back I cut it open and take a look. Im waiting for it to blow up so I can bulid a bigger one and It won't.
Bill
Oh ya sorry, this was a compression ratio question. put 10.5 in and run 91 oct gas.
396, It is purely a budget issue, I have put over $15,000 easily into the boat in the last year, as the boat is a stringer up restoration. The wife's face starts getting all contorted and she makes these scary noises every time I even mention the boat anymore. This was supposed to be a $5,000 project
Joe,
I can't remember if this is a jet boat or not (matters for how much cooling water you have access to), but if it is, I would say you could run up to 10.25 with proper attention payed to your cooling system pressures and a requirement. If you were running aluminum heads, you might be able to push it further, but for 91 on iron heads I think 10.25:1 should be safe.
Check on the pricing for the splayed main kit and labor while your here. Not saying you have to do it, but if you're planning on upgrading the top end at a later date, you wouldn't have to pull the motor again.
As important as the compression is, its the attention to your cam grind that is going make or break the motor's performance. Look for a nice hydrualic roller grind that works with your compression ratio and airflow and things should work out well.
Chris
I would go for around 9 to 1.
Chris
there are alot more 2 bolt blocks running down the track then 4 bolt blocks. just something to think about. I have never seen a 2 bolt main cap broken. anyone???
If you are truly that concerned stud the 2 bolt block and you should be good for 1000 hp.
Omega
You need to figure out your DNC (dynamic compression ratio) with the cam you're going to utilize before working the SCR (static). Often times pump gas and an early IVC (intake valve closing) can warrant more compression ratio than your normal to seeing.
Also consider how the motor was built; IE deck height and quench. Very important factors to the DNC
~Ty
Thanks for the posts everyone!!
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