9.8 deck 598?
 

Is there many 598's out there with a 9.8 deck?

The most you could get from a 9.8 short deck is 588 CI, 4.375 stroke X 4.625 bore.
638 CI with 10.20 tall deck 4.75 stroke X 4.625 bore. Then you get into super tall decks with almost 12 inches of deck height raised cams ect, they max out around 750 ci. And if you are Sonny Leonard you are the king of the hill with your 1000 ci works of art 1005ci to be exact.

Dean

4.5" stroke...In drag cars/boats yes. I wouldn't venture to say 'tons' though. In endurance applications including offshore boats, I'm gonna doubt if there is many or even any. LOL.

Tks. I know there out there just haven't talked to anyone personally that's done it. Wondering if there premature piston/ring wear etc? The 4.5" Crank Clearance must be extremely close but is being done.

With the 4.5" stroke the rod angle is out of acceptable range, and the side load of the pistons and cyl walls is astronomical.

Dean

4.250 is the longest stroke i will use in a 9.8 deck block.espically a blown application.

Against my best wishes a friend just built a 9.8 deck, 4.375 stroke X 4.560 engine. It has Profiler heads and dyno'd 830 hp NA. Supposed to go in a 26' Nova on an XR I built. :pray:

The 850s, 1075s, 1100s, and 1350s are 4.375 stroke.

Dean

Aren't they on a tall-deck 557?

I don't think so, even they old Bulldog 540ci 500hp were 4.375 stroke X 4.44 bore.

Dean

Nothing wrong with a 4.375" crank in a short deck. 4.5" is a bit much for a short deck boat motor. It's hard on the Pistons. If you don't mind putting Pistons in the motor every year or every other year got for it. A 598 short deck will make more power than a tall deck.

They are also built on a 10.20 block

1100&1350 don,t use either std or tall deck.they are not based on 50 year old block design.

why will a short deck 598 make more power than a tall deck 598?

most guys complain about changing valve springs&lifters at 300 hrs so i think changing pistons every other year won,t work for a marine application,jmo.

The shorter the deck the better the path from the Carb to the intake valve. This is why Dart makes 9.6 race blocks.

Some good info guys. Tks! The application would be for NA engines that would only see apprx every other weekend for roughly 3 months out of the year type boating. Mostly pleasure boating with an occasional Busch light taking the helm with the pins down bouncing off the rev limiters. Ha..

Even with engines pulled every other season for routine maintenance/inspection I do believe I will use better judgement and begin gathering parts etc with having 565's in mind rather than 598's.

more power,maybe a few horse power like in pro stock but no good for longivity.i once viewed a short deck 598 with the pan off,even with a very short skirted piston the oil rings almost left the bore at bdc and the ring pack was stacked,the owner found out the hard way that it was a mistake.he ended up bying pistons,rods,push rods and a tall deck block so he could go racing.he ran the tall deck engine all season without an issue.just saying.

There are guys that sell 598 short decks with a warranty now. In the beginning there was no warranty as the development progressed builders started offering a warranty.

how long is the warranty period?not that i would ever want one.

Funny you mentioned that. Here's one I just ran across.

Panther, what's in that motor for a cam?

This a 572 then? Also does he have any time on it yet? I'd really like to keep in the loop on this.
Thanks
John

^^^^^^^^^^that would be a 572[571.59]

Curious as well. Also runner size. I've seen these builds from 320 to 370 plus. Same with cams. I've seen good numbers with short duration like 235-240 all the way up to 260-270 while still keeping rpm's under 6k. Some of it doesn't even make since to me how it's achieved to be perfectly honest. Lol.

Ah. You got me. Lol

Ok here's my 2 options I would like to pursue.

Option 1)
9.8 deck, 4.25 stroke, 4.590 bore = 562 ci

Option 2)
9.8 deck, 4.375 stroke, 4,590 bore = 579 ci

I would have to agree that option "1" would be the best for long jevity etc however if option "2" is proven without any real known issues then I'd like to go that route. I ultimately would like to achieve 775 hp plus or minus at 5,800

It's got a hydraulic roller in it. Somewhere in the 250/260 range. Only dyno time so far. It has the Profiler Sniper heads. The builder said the circle track guys are doing this a lot now. I dont know if I believe ot yet. I'm curious to see how well it lasts.

^^^^^^^^^^^^^^^if going in a boat i would choose option one if useing a 9.8 block,option two for a 10.2 block.

Makes total sense in circle track in the regard of lower weight and lower CG. Racing does not always make $$$$ sense though. LOL.

Warranty don't do chit when your missing seasons... that's why I went 540 not 565 in new engines using the 4.25 crank I might have been ok but was worried about rod angles.

The difference in angle between a 4.25 and 4.375 is about 1.7 degrees

Compression height goes from 1.29 to 1.2275 which both give you plenty of piston.

Getrdunn im building a 565 with a 4.375 stroke right now that I'm going to be selling tall deck

I've done lots of 4.375 short decks, some are over 10 years old and have been in for a few freshen ups. I don't see any more wear that could be attributed to the little extra stroke then I do on a 4.25 stroke. On endurance stuff that's going to run a decent amount of boost 12+, I usually go with the 4.250. I don't know if it really matters, the 4.375 would probably be fine but I like shorter stroke and bigger bore given the choice. The other consideration is piston availability is usually off the shelf for the 2590stroke and you need to do a pin height change on the 375

He said the skirt was very short and the pin was pretty far up. He also used a diamond piston with coated skirts and gas ports.

My new boat has short deck 572s in it. Been in there for quite a few seasons and one freshen up no issues more than any other

I think we're gonna be doing similar builds. You going NA or SC? I sent you a pm last week regarding cam. I need to stick with 9.8 for clearances etc.

Any suggestions on Pistons with the 9.8 deck, 4.375 crank and 6.385 rods? Wondering what shelf Pistons to be looking for and what pin heidth also - 1.21, 1.22? Would like to avoid custom Pistons however If need be not a huge deal.

Good question on the pistons.

For instance, my 572 tall-decks have a 6.70 rod. Oher than some flat top pistons options, dished pistons were like non-existent off the shelf and I had to go custom.

In retrospect if I built it from the ground up I would have gone 6.535 and I don't think the longer rod made all that much of a difference in the rod angle/wear and dwell benefit.