572's with inter cooled 14-71's
 

So I picked up some 14-71's with blowers shop inter coolers. How much boost will I make before detonating a 9.6 static with a 254 264 @50 .632 lift 112ls cam ( basically a crane 691). Not looking to make 1200 hp here, just looking for 800-850 hp. Motors make 650 in there NA state. Leaving compression and quench we're it is after talking with several local builders. Being told I can make some decent power with my current compression and turning the big blowers slow and intercooling. Thoughts???

Aluminum heads I assume. I'm surprised you didn't just do a 800 NA build. Regardless back to your question 3-4 pds max I'd say. I'm sure some will say more and have done so without issues but I personally wouldn't go any more than that on marine engine. What kind of boat?

Yes, aluminum heads. 28' daytona eleminator tall deck.

Sounds like a good E-85 build and crank up some boost. :)

:D,:D
well my first thought was 5-6lbs,,run the daytona boxes w/ knock sensors.or go full on efi.

Rob, you should be able to 4-5lbs of boost, on 93 octane, and meet that power goal. A good ignition with timing control, and watch the fuel mixture, and should be fine. i have a friend who's been running nearly the identical combo, without intercoolers, 4lbs boost, for 10 + years.

They will be tuned on the dyno to be safe, and then rechecked in the boat. But I am just curious because all of the compression to boost ratio chart says 4 pounds is about Max maybe 4.5. However, they don't take into consideration big blowers, inter coolers, aluminum heads, and 100 degree block and head temps. My local builder thinks we will startabout 5 pounds and then inch it up to see we're it starts getting close to being on the edge.

I figured I'd be on the low side.

Its very possible that you can run more boost. However, I can't in good conscience , say "go for it" lol, never tried it myself. Realistically though, it shouldn't take much more than 4-5lbs to hit 800-850hp with a 598, assuming it has decent set of heads on it.

I did run 7psi without an intercooler, with 9:1 and aluminum heads, never had an issue.

MT what your static cr? Seems like you were running 7-8 pds boost. Also what's opinions on intercooler chillers if your not running long distant wfo runs. Majority cruising etc and under 3k. Thought you did some air temp testing with/without.

Disregard above post. Got sidetracked while writing and you had alrady answered pretty much what I was asking.

What's a good ignition setup? Going to be changing this as well.

Turn it up until you see the IATs come up. Then back it down. If you're doing it on the Dyno put race gas in it while experimenting.

A lot of the extra power over your old combo will come if you spin it faster.

Daytona boxes,,just google them.:D

Mine currently is 8:1. Currently, I am at 9.5lbs of boost. Intercooled.

As far as the intercooled, vs not intercooled, I have not seen either setup, elevate the temperatures on long runs vs short runs. In my combination, the intercooler seems to reduce the air intake temps, around 25-35 degrees vs not having it.

A 10-71 right around 1:1 ratio, is making 135-140* intake temps. Believe it or not, the intake temps actually cool down when you open the throttles all the way up, vs cruising. Partly I believe because of the added fuel, and partly because, you are simply passing more fresh air thru the blower/intake/engine. The temp seems to rise AFTER a hard run, and you come off plane and idle, it get a little hotter there.

Have cometic make some head gaskets to drop compression ratio. May need pushrods and thicker intake gaskets after but you will have a safer set up.

I agree, or yank the heads, and if stock, have a good cylinder head guy, port the chambers, and make sure they line up to the bore size. You'll lose some compression, and unshroud the valves/help airflow as well. Im sure a 4.600 bore can accomodate.

What heads are they rob?

How much will a intercooler lower the boost?
At 25f-35f degrees lower?
How about more like 50-60f lower what does the boost do than?

They are the edelbrock 118cc heads made for gm's zz572 crate motor. I want to run a thicker cometic head gasket but I keep reading about quench and how I might actually make detonation worse by opening up the quench. I am going to see if Valeko can port the chambers and lose a few cc's while he is installing the inconel valves.

These look sweet!!! That's what I will be doing.

Mercury 1075 runs flat top pistons in the hole about .075 maybe little more so I don't think detonation is an issue.

I havent seen 50-60 f drop from the intercooler vs non intercooled, in the couple applications ive played with. I would think, the boost level would drop, but power go up.
Those roots blower intercoolers, do seem to be a pretty good restriction.

I made 7lbs boost with blower at 7% under. When i changed the engine combo, lowered static, changed heads, added intercoolers, i had to be at 8% over to see psi. Being that i changed several things, hard to say . Did i lose boost because the heads flow better? Air temp cooler? Restriction of the intercooler core ? I really dont know.

No kidding...!! Everyone seems to have a different opinion on this. Especially in blown builds. It sure would be an easy way to get me to upper 8's or 9-1 since the heads have to come off anyway for valves.

[QUOTE=rob vanharten;4496038]No kidding...!! Everyone seems to have a different opinion on this. Especially in blown builds. It sure would be an easy way to get me to upper 8's or 9

Don't spend the money on the chambers wait till you want to up grade the heads to something better. There is a set of CNC brodix heads on ebay with Inconel valve came off a boat freshwater cooled. Don't know if they are better than what you have. Think 2100 ish per set. OBO They look very good.

Flat top piston will run cooler less surface area.

Those the 345 cc brodix heads. 2.25 int valves?

think so
shows 4 of them in picture they are not bb4 heads

So roughly 8.5:1 or less. .075 below deck is a point itself.

IDK just using it for example. That's why t brought up the 1075 piston in the hole just through some big head gaskets at it and be done.

My pistons are flat tops with a 3cc valve relief. Any idea how thick a head gasket they ran on the 1075? If I could run a thicker gasket that would be so.... nice!! Mine are a compressed .030 stock. Some .060-.080's would make a big difference.

Those are the ones. Been on there a while. Make offer for both. Those would work well for his builds.

Merc 1075 is actually 7.9:1 comp

Other thing to keep in mind you can always open up your chambers about 5cc's and lose .3. Every little bit helps. Btwn that and .060 gasket
Should get you in the high 8's.

7.9 is right,,I'll have to look at the receipt for the gaskets I ordered.they were cometics.if you can't wait till tonight,,maybe give cometic a call.

I can wait, great info guys!! Thank you.

1075 has .051 head gaskets in it. You can get .125 head gaskets from cometic but they are pricey. Or what ever you want made just next day ship them and they are don in three days at least the last ones I ordered where.

I'd go with a .060 head gasket if you have a .040 on it now and call it a day. Those blowers are really big for what you're doing. In fact, you might be better off with a smaller blower for distribution purposes on such low boost. I would think 9:1 compression and 4-5 psi would easily be 800+. You might actually struggle to get the power that low and wind up with a 900hp engine with low boost.

For comparison purposes, I have 572's. I used to run Merlin Grumpy Heads years ago and my compression was 8.3:1 on a cam that's somewhat close to what you have but solid and made 838HP at 6K rpm with an 8:71 blower and 6psi boost, no intercooler. Fast forward a few years ago, I put AFR 357CNC heads on it and I never dyno'd but I estimate the power was close to 900 hp since I picked up 300 rpm and didn't change anything else. Then two years ago I completely rebuilt the engines with new blocks and pistons, running 8.4:1 compression, 8:71's and 6psi boost netted me 965hp on the dyno. That was also good for another 200 rpm gain in the boat. I also installed a methanol injection system in place of an intercooler and with Meth the boat runs 95.4 mph and without it activated the boat ran 94.5 mph. All 572" stuff...

This amazes me!! Are we 100% sure a factory 1075 has flat tops .075 in the whole and a .051 gasket? NOT doubting your knowledge or intelligence in any way shape or form!!! But if I am basing my build off of those numbers I want to be certain of it. I love this site, you guys are all great:)

I am not certan of the .075 in the hole but its deep and no doubt they are flat tops. I do believe I have a few pistons here from a rebuild I did before. I can figure out how deep it was if you want to know. Compression height take me a minute later tonight.

Just looked up gaskets they are .051 head gaskets and .051 for intake. Intake uses a MLS also.

If you wouldn't mind double checking the hole depth I would really appreciate it!!

For what it`s worth , run it rich. According to my knock sensors and AFR gauges the motors are quite a bit happier at low to mid 10`s then they are at low 11`s. @WOT

With that set up I'm coming closer to 8.24 however go to Wallaceracing compression ratio calculator and play with the numbers. Merc might use a flat top also with a bit more valve relief. Either way you can get some ideas