PSI 8.8 liter / 550ci ???
 

I see these industrial engines on ebay and they are built on the Gen7 8.1/496 platform.

https://www.ebay.com/itm/23471275582...Bk9SR9LRjOmBYQ


Last one I looked at was @ 4.350 bore x 4.500 stroke...

Intake and ports look a little small but they are selling complete, intake to oil pan @ approx $1500-$1800.

Even if I toss the heads in the dumpster and use the shortblock as a rebuildable core, I can hang Raylar heads on it and be @ 550+ cubes pretty cheap.

Otherwise Im looking at $2500~ish for Dart 4.500" block and $600 for a 4.5" crank.

Thoughts ???

My understanding is that PSI bought the tooling when Gm discontinued the 8.1 so these should be functionally very similar to that. Gen VII so you can't use earlier cylinder heads on it, Raylar pretty much your only choice as far as I know.

Yeah I currently have a VP 8.1 and was hoping to keep the same platform when I make upgrades so it looks and functions like OEM.

Obviously cubic inches are always the answer... and this looks like a pretty cheap score if I can use the shortblock.
If the Math doesnt shake-out, I will likely just build from scratch on a Dart block and forged crank.

Dart had a head listed for the 8.1. Not sure if they are still making it?

535ci as from PSI. 572ci if you stroke to 4.750".
Yep, it's compatible with gen 7 8.1 platforms. The block is a nice piece with individual piston oil squirters. Can be bored to 4.400". 4.500 crank. Minor grinding will fit a 4.750" crank. Stock shortblock internals from PSI are forged. Though the pistons do not have a large valve relief as most performance pistons. PtoV needs checked going bigger than Raylar 203 cam. The PSI heads are junk for power usage. Designed for BIG torque under 3k rpms. Raylar and Dart heads will bolt right up. Raylar has a new 90mm alum intake out very similar to the LSX intakes.

Good to know.
I saw pictures of the PSI intake and while the 91mm throttle body mount is a plus... the intake ports are terribly small. Nothing like the tall cathedral ports on the stock 8.1.

I think the Raylar heads and cam on a fresh PSI shortblock might be the cats whiskers.

Why not just go the entire Raylar route? They are the de-facto experts of modifying 496 platform and you will probably be ahead of the game when it comes to cost. Especially if you want to upgrade HP and maintain stock appearences.

Larry will tell you to go with a PSI shortblock. He sells them. It's a better than stock block. Also has a bigger bore. 4.350" vs GM 8.1 @ 4.250". Only real downside is that it has 1/2 x13 main cap bolts and no windage tray provision vs GM8.1. GM main cap studs are 12mm and cannot be used on PSI block.

If wanting to run a windage tray setup in a performance PSI 8.8 block you need ARP main studs and align hone accordingly.

This one?

https://www.raylarengineering.com/vo...te-engine.html

Spot on!

Nice, would be cool to see what could be done on a budget. Aftermarket heads and 4.75 cranks probably aren’t worth it though. Just start with a dart or world block that can go 4.6x 4.75 for $3700.

Ive swapped a few emails with Larry at Raylar... and will eventually buy heads/cam/intake from him... but I typically prefer to do my own assembly work and have machine work done locally. It saves me a ton of money and I have my hands on it every step of the way. Been building engines for over 35 years now.
Larry has done great things with the gen7 engines... but I can build a budget shortblock for substantially less by doing it myself.

You’ll come out a little ahead $$$ if you don’t want more than 572ci.

I like to stud everything I build thats not a bone stock application. Ive seen main caps walk around too much on bolted stuff.

I will watch ebay for a PSI motor. Seems like that makes the most sense for a rebuildable core. I can scrap the top end and still be ahead of the game by just using the shortblock.

What will you do for exhaust? A few options out there and all will require some work to get routed out those side exits.

Stainless Marine and CMI make stuff that is +6" to match my current system. Already looking into it.

FYI Trey at River Speed and Marine is in with PSI and building up the Gen 7 platform. He has PSI blocks and cranks available to sell.

He's in development of the LS platform heads for the Gen 7 that Chevy developed and never brought to production. It would be worth calling him.

I saw those heads. He had a ported set up against a Raylar head. They both were looking really good. That head also uses LS rockers from what I understand. Like to know more about what intake it can use.

The PSI rotating assembly is a great base. The big question is are you doing the HO600 or the HO525 package?

Somebody post the link/picture of the River Speed and Marine heads. Are they compared to the Raylar stock aluminum heads or the Raylar racing CNC heads?
FWIW, the Raylar heads were designed by Reher-Morrison and 10 years ago, I dropped them off at 2 places to port them and everybody knew the story behind them and insisted that the only thing they would do is screw them up. That was 10 years ago but they are pretty decent bang for the buck.

Mike Head use to be one of RM top cylinder head guys, not sure if he's still there been yrs since Ive been to the shop.

Yup. Darrin Morgan when at Reher-Morrison. :thumbs

Jury is still out... and Im just in info-gathering mode right now... but Im thinking a 4.350x4.500 shortblock with Raylar heads/cam/intake would probably be somewhere around ~600-ish HP and still idle nicely.

River Speed and Marine, contact Trey for more info.
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Gen 7 LS BBC
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Yes the PSI block is just that amazing. PSI has several variations of that block for its different applications. The best block is the R block shown above. Superior in every single way. Very literally built for high cylinder pressures and high rpm. Those LS based heads are an absolute improvement over any stock 8.1 head ever produced. I own River Speed and Marine. We started on this journey years ago when Larry and Raylar had only seen about 800 hp max on a 496. I built one with HP3 heads and a procharger that leveled out to approximately 1700HP before breaking a crankshaft.
RSM had a deal with PSI to build these motors for the OEM world. RSM is an EPA certified OEM for spark ignition marine engines. Unfortunately Covid and supply chain issues kept us from opening. We wanted to order 200 blocks but what was given to us was 10 complete blocks and they opened the door to these mystery heads. I have heard about these heads for some time. I could not get PSI to let me buy them. They finally relented in December 2021. They are amazing, Injector over intake valves, injector in head, 15 Degree valve angles massively reduced shrouding, small combustion chambers. LS Exhaust rocker arms. ETC. Substantially larger cooling between intake and exhaust valves. the list goes on.
The intake picture above was design by Arizona Speed and Marine for GM "back in the day" ASM still manufactures ALL the Mercury Blue motor intakes and still to this day designs intakes for Mercury Racing.
We are currently building for testing 2 variations of the 9.0L motor. We go to a complete 9.0 liter 547/548 CID on this block. The two variations are LS9M and LS9R, those designations are for us internally. The M Series is being designed for a 600hp/600tq 496 replacement using stock 496 heads, drop in and plug and play. for under 10K way under 10K using forged internals. There are some very tricky issues with this as the EPA has some very hard rules and laws about this.
The R series motor uses the LS style head, It is currently being ported and plotted for CNC use. We are making the R LS head to flow low 400CFM with large valves. We will produce our results when we have the complete recipe. The R motor we are shooting for 800-900 NA with a redline of about 7100 rpm mild idle and DBW. We will also be using Procharger to boost the very same engine to make 1200-1700 hp on race fuel.
Frankly its lost cause though. The market for 496 replacement engines growing but that's it. NEW OEM GEN 7 motors just wont be used.
RSM is going to finish this project publish its results and formula but we are moving on to the extreme HP hybrid marine propulsion systems. Using micro turbines and the latest water cooled EV motors and water cooled battery packs.
We also partnered with MDC to produce the anticavitation device for bravo drives and we have worked with other companies to design and build other products.
Engine development is slow and costly but we are getting there and sharing this data with part manufacturers so there is place for engine builders to go to for timed out 496 owners who need replacement blocks.
We are currently doing a build for GripTec/ZPE/employee we will have this done in December and they will publish the results. It will be the M series motor using 3.3 whipple and 555 ecu.

We consider Raylar a friend, Larry has spent 100's of thousands of dollars on the development of the 496. His work, (Larry's) should be respected. it was a tragic and only a financial move that GM sold off the venerable 496 in the midst of the financial crisis. That move alone was crushing to the leaders of the day such as:
Raylar
Innovation Marine (they still have 20 brand new in crate HP3 Motors)
Arizona Speed and Marine


Hope this helps.

One more thing. WORLD does not cast these. They did not design this. PSI still uses the external casting box for these motors and if you call World, they will tell you they do not manufacture or design anything you are seeing. Its simply an external casting box that still has those markings.

Is there any way to determine which blocks are which from an external "junkyard" viewpoint ?

Ive found a few rebuildable cores online and would prefer the "R" block and better heads if I can narrow down some of the visible details.

Are the head-mounted injectors exclusive to the trunnion style rockers and shallow valve angles ? or is that prototype-only stuff ?

I also see the bolt-on intake valley pan... is that exclusive to the better block ? or do they all look similar ?


Thanks in advance... just trying to nail down a good core to play with.

The block casting number is 80000795R

PSI made three different valley pans, three different intakes th elates of which has orings around the ports.
ALL the LS Style heads have injector in head

the picks you show should have Kellogg Heat induction forged cranks. Scat manufactured prostock rods. Some also have forged pistons. Dished pistons are 9.1 Flat tops are 10.1. All the rods are bushed.

The injectors with plastic and red are NG
The others are gasoline.
The natural gas motors always come with 10.1 compression pistons.

Wowzers... sounds like a great starting point.

Thanks a million for the info !!!

Where does PSI put the block/casting number ?
I asked the seller and he is as clueless as I am.

Passenger side rear on block

https://cimg9.ibsrv.net/gimg/www.off...ee1521882.jpeg

Thanks !

Seller did confirm that he has two of the 80000795R longblocks available... so I just purchased both @ $1500ea + $225 shipping.

Hopefully I can build one good one out of the pair... assuming they have good parts inside them and have the better LS style heads.

Assuming both these engines I just bought have the LS style heads on them... are they substantially better than the stock cathedral port heads currently on my 8.1 ?
If I can get away with using these LS heads and intake instead of buying the aluminum Raylar heads... that will save a bunch of money also.

I'm not looking to spin this thing to 7k... I think 5500-5600 is plenty. I can prop the boat accordingly so I dont need to spin it any faster.

Maybe a fresh rebuild with the right camshaft will work... AND save some money.

What do these LS style heads flow and how do you identify them? Valve size? I assume they are cast iron?

From what I understand... all the LS style heads have the injector bosses integral with the head... and yes they are cast iron.

I cant speak to the valve sizes or flow numbers but would really like to know also.
If they are significantly better than the 8.1 cathedral port heads, I will give them a try.
I might get away with just dropping a bigger camshaft in a fresh PSI longblock if these heads are a viable option.

Seller just sent me a couple pics to confirm what I bought.

Looks like both are definitely the correct 80000795R blocks.