MTScott

Just curious if anyone has done this (I'm sure SOMEONE has). Overall, there is nothing wrong with the stock rect port heads, but I feel like a lot of power is left on the table with the low (8.6:1) compression ratio.

The engine has 420 hours on it, so it is still has a lot of life left in it.... I don't feel like breaking it down and doing a full build.

I've found these specs elsewhere on determining stock compression ratio, but this guy comes up with 8.8:1 (oem rate from what I understand is 8:6:1)
This does yield 8.8:1, but other's chimed in and said they measured pistons to have less dome, and measured larger volume combustion chamber (like 121), etc... one said his pistons were 0.025 in the hole, so, perhaps one or a combination of those brings it down to the advertised 8.6:1 on the 454mag.

This edelbrock product here has 110cc chambers:
https://www.summitracing.com/parts/edl-61459/overview/

If I were to swap these heads on with the above quoted specs, it would yield a compression of 9.45:1, which should be plenty safe for pump gas.

I would think this bump in compression would make this engine run nice, and I imagine I could sell the stock heads easy enough to someone with a 7.4L 330. Shaving 60lbs off the engine would be nice too, as the main reason I'm doing this is so I can run this thing out of the hole better and still have a decent top end (I've had to prop it down to a 17P four blade, if I could run a 19P and get the same holeshot I'd be happy). It'll cost $2200, but I can have them on in a weekend.... it is tempting. I could see possibly swapping in upgraded manifolds as well, and shaving off even more weight.

Also, this engine will never be in salt water.... so, that isn't a concern.

Thoughts anyone? Feel free to talk me out of it... I don't NEED to spend this money

Side question, does the gen V run a flat tappet, or a roller cam? My assumption is flat tappet.

dereknkathy

I have heard 1 point of compression equals 3% in power output. I don't think it is worth it. I have also heard the edelbrock head is not much better than the rectangle iron head for power output. If you wanna spend 2k for aluminum heads, spend 2500 for afr or brodix. The mag intake is a very good piece. Spend the 2k on a roller cam and lifters and a good used set of gil exhausts. And you will be well ahead of eddy heads on that mag setup. Your hole shot is not so much a function of your power though. You are coming up on plane at about 2500 to 3500. What is the boat and drive?


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mike tkach

iTrader: (3)

best advice you have given,the only advantage in using the edelbrock head ts the weight saving,no power increase will be seen.

mike tkach

iTrader: (3)

best advice you have given,the only advantage in using the edelbrock head is the weight saving,no power increase will be seen.

phragle

iTrader: (3)

A friend of mine has the Eddie heads on a 454, you can make some power with them, they arent too expensive but there are better choices out there, Any heads you get arent really going to be bolt on.. I believe the eddies come with stainless valves but no springs etc....

MTScott

I'm not hung up on Eddie heads... I'd consider something else. It seems like my expectation of higher compression was naive. IS there a head out there that will make a significant difference? I also don't simply want a high RPM screamer, this is a family boat. I'm really more interested in increasing power through the whole RPM range. Perhaps heads isn't the answer. A blower is probably a better solution. I do like the idea of shaving 100 lbs off the back of the boat with heads and exhaust manifolds, but, I'm not sure the weight savings is worth the $4000 it would cost me.

MTScott

Sorry, I guess I didn't answer this completely. Formula, 252, 1993. The boat weighs about 5K dry, from what I remember. Bravo 1 drive. I've got my holeshot in a decent place by adding a 17P 4 blade prop (turning point aluminum)... i've gotta be over 3K to make it plane, and then I can run it around 3200 to stay on plane at the lowest, trim tabs are needed sometimes to do that. It'll over rev easy now, and I'm not much over 40mph at 5K rpm... maybe 45.

I've also considered the idea of swapping on a bravo 3 lower unit. I'm hoping to set this boat up for some wakeboarding for the kids. I know it isn't the right boat for that, but it is what I've got, and the wife really likes "this" boat so you know how that goes.

Baja Rooster

iTrader: (1)

This might be a worthy read if you haven't been in the General Tech section lately.

http://www.offshoreonly.com/forums/g...s-arrived.html

I have those Eddy heads but they had some work put into them before I got them. When I took them in to get freshened up the machine shop said that they quit selling the Eddy heads because the quality just wasn't what they use to be and there's better alternatives on the market.

dereknkathy

Ederblock?

MTScott

Those promaxx 317 heads can be had for around $1500-$1700 a set, that's cheaper than the eddy heads. Similar AFR heads are get up near $3500 a set.

The Promaxx cost is almost cheap enough to just try it out. On Jegs the "up to .600" lift heads are $1440 a pair. I think the stock cam in this engine is in the mid .500s??

I wonder if these are chinese castings.