Limits of stock Forged rods?

I have successfully fixed my detonation issues and am now running my water/methanol system off of a vacuum switch. I'm now running a 114 hp nitrous shot and the engine is handling it effortlessly. I have my 2step set at 2500rpm, the converter stalls at 2800, my high rpm limit is set to 7000, the nitrous window switch is set at 2800 on, and 6000 off. This thing really screams at 6000! I'm thinking about pushing the nitrous limit to 6500. How much abuse can the stock Forged rods handle? What was the highest hp that someone has run without switching to custom rods? My rods have ARP bolts installed.
 
The longer stroke, longer rod and bigger main bearing tall deck version of the 200 can cope with 350 hp with forged rods and the rod bolts are the limit. The 200 should be okay to 280 hp based on the critcal loads. Pistons are the critical part...ring flutter sets in, and the tops come off the pistons or the skirt cracks. Nitrous is like 7 pounds of turbo boost. Always limit it to 1.47 times your stock non boosted power. If your engine is like Ken Lovings triple carb 200 then you may gave 185 hp without boost. Adding nitrous, Id stop at 272 hp .

90 hp shot; that is it. Rev limit needs to be dropped back to 5800 rpm.

IMHO your way past the pushing your luck stage. It a miracle its not broken now.

Enjoy it!
 
X, are those numbers for cast or Forged pistons? My pistons are custom with the round oiling holes. I believe that the rings are a little thinner too. The pistons are also lighter than the flat top tempo 4cyl pistons that I was running. I did end up cracking one of those with a 90 shot.
 
Stock Ford Australia issue Duralite pistons were cast alloy for all in line sixes untill the last of the line turbo DOHC's which got CP pistons. The good cast alloy pistons will take 350 horsepower, but its peak feet per second thay kills them, so 5800 on a 200 max is just 5000 on a 250. A 25% stroke change gives you a 25% peak rpm increase. As Ford moved to the hypereutectic cast alloy, they moved to more modern ring packs with less drag, but they are clearanced for 4500 to 5500 in the 250/239 cube Australian Cross flows to maybee 6000 on the last 243 twin cammers.

Everything is fine cast alloy piston wise, even the 2300 Tempos, untill you get ring flutter ..or detonation due to lean fuel with nitrous. That might mean you can take 450 hp like Will and Kelly's 250. If your piston survives that, then the wrist pins fail due to rod beam bending. 280 hp is all id expect of those rods...but a few triple carb 170 s make 280 with stock C1 4.715 inch rods.

Enjoy your engine. Like the car you drive, but be very carefull not to over advance it, or add more than 50 % of the gasoline flow in water. Water will quell detonation, but atmosphere of nitrous oxide is oxgen, and without Excess Fuel right in all six cylinders detonation sets in too soon to prevent damage. Nitrous has never killef an engine...its insufficient fuel to match the oxygen that is liberated by the atmosphere nitogen brings with it. The excess fuel factor eliminates nitrous oxide alowing a lean torchdown. The oxygen supports blowtorch cylinder conditions.
 
If you ever go 2618 forged alloy, be very carefull of this.


Too much clearance with 2618 alloy.

2618_mahales_at_12tho_ptb.jpg





2618 or 4032...these forged alloy pistons are exceptionally strong and run up to 100 deg F cooler under nitrous or turbo conditions than most cast alloy. If 4032 alloy, they are quieter at idle when the engine is cold than 2618 alloy.


Excessive piston slap when cold causes cracking and clearance needs and cost is the only reason you don't see more forged pistons around.

Blair G was on a fast track to Engineering sucess as a Roading and Mine Engineer of exceptional abilty.

I was a year behind him at school, and he asked a boat load of questions when he bought a 5500 dollar engine from the news paper after the NZ saremarket crash. After the engine was built up with the best parts and advice, we sadly scored a bore in an XE stamped 351C NASCAR block in 1988.


It had TRW's 2618 alloy forged pistons but still did 22 mpg, and made insane power in his Beige 1971 XY Falcon 500, with an 8.5 second 1/8 th on his street one wet night. With me on board.

It had a funny ENGINE NOISE noise at 1500 rpm....

We had to downgrade to a standard 1977 Geelong casting 351C, and US Speed and Spares built Blair up a new 30 thou over engine, and valued the scored block as a 60 thou over 1500 trade on a 3500 dollar engine. So lesson here is that the best block is always worth something, even if you score the bores. No 351 C can take 60 thou over bores EXCEPT some the last thickwall XE castings made for Ford USA BY Ford Australia.

In 1997, it got stollen at the Wahi Mine.

1971_XY_FALCON_500.jpg


I've seen a lot of old beige Falcon 500's around in hedges and in Sims Pacific skips, and I always look for Blairs old Falcon 500. Those square Flacons and the Torino it was based on were exceptionally good machines.

Too little clearance is worse....Blairs had too little clearance.

4032_JE_2400_MOPAR_at_04tho_ptb_001.jpg


4032_JE_2400_MOPAR_at_04tho_ptb.jpg


A very delicate run in for the first 1000 miles if the piston to bore clearances are large. If its very tight, you need to baby it for the first 5000 miles with occassional blats. Its like polishing silver ware. A mixture of hard and fast, and low and slow but always polishing. Your putting the spit and plish on the internal parts, linishing them like and expert.

Piston knock can be eliminated by plateau honing and the bore texture and piston and ring clearnaces make the engine work well long term.

Forged pistons are not a cure for all engine ills...they need a lot more bore, PTB, Torque plate and ring fettling than a stock Ford cast alloy piston to work.

Ford classically bailed on the forged pistons for the 1993 model year after two years of Turbo Carb 2.3 forged pistons from 1979 to 1980, and then, IIRC, 1983 to 1992 in the 5.0 GT HO spec engines. The turbo EFi 2.3 had them from 1983 to 1988 IIRC.

All of them were loud engines, missing the smootheness you'd find in a plateau honed 5.0 Explorer or Mountaineer V8 engine.
 
Thanks for all the info. I will take your advice and stop where I'm at. So far I have not heard any strange noises other than the detonation when the nitrous was not active. My af ratio is always slightly rich about 12.5 -11. Last time I checked the spark plugs, they all looked pretty normal, no aluminum speckles. I also run 20w50 oil in the hopes that it helps cushion the Piston side load. Water/meth is always measured to 50/50. the block has also been re-sleved.
 
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