8.1 liter forged rods and pistons
 

I am looking for a few options on suppliers with forged pistons and rods in stock. I have seen Raylar's stuff nice but looking for options

i think scat is making a forged crankshaft and h beam rods for the 8.1.

Use a 6.7 inch rod with a 2.2 .990 These are off the shelf rods, get any brand you want, get an H beam.

For pistons, use a Wiseco PT121A1. Also, you can have the relief fly cut the piston another 30 thou, from .280 to .310. Straight from Wiseco they are 677.32 with the fly cutting. They are the better 4032 alloy and have coated skirts.

If you want to keep the stock rods ( they have a 1.04 pin) you can get Wiseco or diamond. I don't know of anyone that makes replacement rods for the 8.1.

There ya go, let me know if you have questions.

Scat is making the stock stroke, 4.500 & 4.750. This is a USA forging, they take about 10-12 weeks. I needed on with-in 4 weeks. Mike @ MK Hammer, sold me one he had coming in to help me out. He also gave me a fair price, real nice person to deal with.
I did a 496 over the beginning of the summer with a 3.3 Whipple, Dart heads (iron) 770 hp @ 5800 760 torque, with 4.5 # boost. We are changing the crank due to wanting to increase boost without worries. Marine Kinetics, did the cam. I used; 6.700 rods, custom CP pistons 8.1 CR, I have another set; perfect for blown application. Here's the deal; you do not need any special rockers, guide plate or poly locks, if the valve lengths are Darts spec length and you figure rocker arm geometry correct. It will fit under the stock valve covers, I used Scorpion Endurance rockers, I bought from Marine Kinetics. Dart adjustable guide plates.
You can buy; the factory reluctor wheels from GM just got some in. I was lied to by someone; saying they bought them all and they are no longer available. Darts cranks are a import and use their own specific reluctor wheels. I'll tell you that's what I found out on my own, and from MK Hammer. I tried to buy; heads from Raylar; I was given the run around and later found out from them they were skeptical of my knowledge on who, designed them, who cast them and the person that completed the cnc work to finalize the heads. I wanted; cnc castings with valves, they wanted me to buy; everything else I didn't want. Like I was some dumb-ass, that didn't know what I needed. So I used Darts or Raylars heads would have been installed.
I don't know what your project is, before you get rolling. Talking to others with experience on the 8.1 will save you time and money.

The CP Piston, they made for me are a 2618 with a .990 pin. No offset in pin location is needed, the stock piston is; if I recall .030" we put .006" piston to wall clearance. I told Dustin, just turn the knock off. I used a 4.255" bore size, they made it from the Bullet forging, due to size. That interference fit piston was only put in there for start-up noise, and going the extreme mileage. I had a long discussion with my engineer @ CP over my concerns on these blower pistons, needless to say ; I worried for nothing. We used a .200" wall wrist-pin also.

Darin designed the Raylar head, not sure how you feel about him, but I think he is a true wealth of knowledge. They are final machined I think at Roush. I believe the place in Ohio is casting them.

Kellog crankshaft was making 8.1 cranks. They are in Jackson, MI. U sure if they sell to public.

The 4032 is better than 2618, but either are FAR superior to the hyper stock stuff. Correct the stock has an offset pin, can't recall the amount, small just to help with noise I think. The Wiseco are stocked which is nice. But in a blower application custom is better to ensure you get the comp where you want it.

4032 is not "better", it is for a certain application. N/A tighter clearances, minimal NO2 and maybe a very small amount of boost. 2618 typically expands more but is better suited for harsh environments such as endurance motors, blower motors, NO2 motors. They are not as hard as the 4032 so they don't shatter as easily when detonation is encountered. My N/A 383 had 4032 wiseco and SRP pistons. My blower 413 motor has Diamond 2618 pistons.

Sorry, you are correct. I should have clarified. I "assumed" the OP was looking for replacements for the stock motors. I feel in that application the 4032 would be a bit better. But hey, I could be wrong.

Your are correct Darin, designed the heads and yes he is in my opinion, one of the top knowledgeable experts. He developed, them while still @ Reher Morrison. He took a short term position @ Profiler, then went back to Reher Morrison. While at Profiler, he redid the BBC Sniper, now currently being used. Profiler (Ray Franks) has done their own castings. I have used their heads back from early 2000. They used a ceramic mold with very fine sand, resulting in a machined looking casting. That has changed now to a sand casting, due to cost. Ray Franks, main business; is casting aircraft parts, to followed over to casting the 12 degree head for Pro Stock, which was illegal. no factory part #s.
At one time Roush, did their machining, before that it was someone else. Greg Burkhart, owner of GT Racing Heads completes the full machining operation. He originally got the contract, for developing the rectangular Sniper CNC program. He is a excellent cylinder head porter, he has done heads for me back before the cnc operation went into full swing. The current cnc Sniper of course is Darin's at this time.
At this time the Raylar, casting is not done by Profiler, nor is the machining done by GT. Those were the words from Larry,( owner of Raylar), to me after the fact of explaining; his reason for avoiding my questions and knowledge of his heads. He stated; shipping from east- west was the cost issue. Here's my take; cheaper casting, same for cnc machining. Guess; I'll call Profiler, and get the other side of the story now.

The cost on the Profiler Sniper CNC head is about $1400.00 each Bare ready for heads.

You guys have found the same answers I did, Wiseco and Diamond were the only two that made them (other than Raylar) there are also a few strokers out there now that werent 18 months ago. I wanted to stroke but couldnt find a crank. Arent either of you concerned about the block? Will one of you please do this with the DART block and 4.5 (or more) bore and the aluminum heads? This could be a badazz combo but I havent seen it done yet.

I have the Raylar heads on my 496/600's - they are nice pieces. Raylar has bigger performance CNC heads now but when I bought mine they werent available. I took my heads to 3 different places in South Florida to have them ported when I bought them and nobody would touch them and guarantee a performance improvement. One of the guys said "Darin designed them, they only thing you can do by fooling with them is mess them up"
I think that says they are pretty nice heads for the money.... Now I want to get them CNC'd like their performance heads and see what difference it makes.

Any decent company will make you pistons...thats all Raylar did, I would guess he is now using the Wiseco's. He is using Scat rods im pretty sure too. He cites in an old post you cant use the stock rods so that tells me he is using a 990 pin, not the stock 1.04.

Scat is making an AWESOME crank as previously mentioned, but I dont think that is what Raylar is selling, cant be just based on price....far too cheap from Raylar so it must be an offshore crank and machined here.

In the end, after all the math is done, cheaper to buy a set of 525s and sell the 496s.

Its close in price and horsepower, but if you do some work I think its cheaper building new. Plus, you have to change the wiring harness so there is some work to be done. The 600's are probably 30 more HP than a 525 realistically but I wanted new. I did 10 different spreadsheets and ended up getting the specs that Raylar wanted, ring end gap, clearances and hone then built it to what they "prefer" had the short block bored and built locally and called in a few favors from the race crowd. I built both mine shortblock up for $26K with long tube 105 Dana exhaust. So when we are debating $1000 dollars, I prefer what I already know. Plus, I have a strange attraction to the 496's :) I really think they have potential to be reliable.

When i bought my 496/Whipple, i was told the rods were changed for a set of Eagle rods and Wiseco blower pistons
(8:1) from Raylar.

Not knocking building the 496s at all. Each their own, I can do it all myself except for machining, but my time is worth money too! After I did the math, in my case, it would be cheaper to buy low hour take out 525 and yes, spend a bit more for "incidentals" and be done.

I decided to keep the 496s stock because after I spend that amount of money I won't be able to recover it so I might as well throw 30k in the sock drawer for my next boat.

PS, watched your videos on YouTube when I was researching and it sounds great!!

I have to agree; My customer called me asking about someone else telling him just bolt the Whipple on top and GO! I have never spoken to this guy, until then. He wanted to keep the engine hatch without any modification. This was an Eliminator deck cat, he was also informed from Eliminator, before calling me; you need to make changes before bolting the Whipple on. He was dead set on using the 8.1 obviously the money was not an issue. In the engine, we could have sold the 8.1 and started over again. He already had the Dana exhaust, and it was going to maintain the closed cooling system. Starting over would have cost more and we have have parts left over.
If anyone wants to buy, a crank, heads, cam, lifters induction system and a wiring harness. I have it available at a fair price or make a fair offer.

What cranks heads and cam and what induction system? I may be interested still.

Anybody have a torque honing plate for rental. My engine shop does not have one for this motor
Before I buy one I thought I would see if anybody help a brother out. I have one on hold for a few days just incase

These are too new yet for any take outs but look like a nice option.
http://www.mercuryracing.com/sterndrives/hp520.php

I have the stock Nodular crank ( Had it polished and inspected by Shaftech INC) stock heads, cam, efi intake, injectors and harness off or the H.O.

Sorry, no; about the only one I don't have a alum or steel plate for. The deck and cylinders are pretty thick, so hardly any deflection.

Are you saying it should be safe to NOT use one. Also can anybody tell me if the marine heads use different valves than GM 8.1 trucks? If not the same anybody have the valve replacement part numbers for SS and Inconel. And maybe a few venders with them in stock as well.

Thank you all for the help I'm not trying to be cheap just cheaper than new drop in's or 525's

1 last thing what is the hp potential of factory crank. I'm sure I will not be close to it just checking

I asked Ray at Raylar (2 years ago) about the crank...I was told 750-800hp; he told me not to worry, at my power level (625-650hp)

Thats what I heard from Dustin too.

Get above the 800 with the stock nodular will break. Raylar, tried to tell me the stock would break at the snout where the pin is that indexes the timing gear. Found out from my crank expert all the diesel cranks are drilled the same way for round pin. They are drilled preventing stress risers, with a step. The diesel guys weld the gear to prevent shearing the pin in high HP applications.

Thanks MER performance very helpful lead you gave me

Would there be any disadvantage, or any reason that you couldn't use 6.385 lenght rods and the correct bore BBC pistons with the correct compression height for the block to build an 8.1 and overcome the top ring land weakness of the factory style piston, and forged versions that are set up the same way?

I recently purchased the off the shelf Wiseco pistons for the 8.1 and discovered they made the top ring land thicker than the factory pistons. I'ts .300" thick in the Wiseco. The stock pistons are .200" on the top land. Both pistons have the same .180" on the second land.
https://cimg0.ibsrv.net/gimg/www.off...83ae3e88bb.jpg
https://cimg1.ibsrv.net/gimg/www.off...a45806025c.jpg

Good to know. Thanks.