SDPC Tech Tips: Connecting Rods
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- Опубліковано 6 вер 2024
- Nick goes over connecting rod selection for your performance build. Selecting the right rod is an important step and has implications other than "what bearing, pin and bolts should I get?"
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#SDPC #SDPCRaceshop #Rods #ConnectingRods #TechsualHealing
Yes. Pushing a tune will break a rod. Clearance checks are important. I have run a V8 accidently to 13,000 rpm drag boat leaving the water in the top end. It didn't have big $$ rods. Stripped measurement ok. Most rods under compression are fine with correct clearance. It's the up stroke and dwell that stuffs them. Stretch. Detonation is a factor but it will take out the piston first. Big issue causing rod failure. Rod and ring clearance plays a big part. Rod alignment to bore and piston is important. Cheers and old race engine builder.
Good stuff
Are there any Ford FE rod that can handle 700hp ? The 390/428/428CJ are I- beams forged 5140 steel and prep with a polish and peen with 3/8 inch ARPs best bolts. The stroke is 3.99,, and the goal 700 hp from 421 ci 4.099 bore.6.488. I like them because they have a great balance of strength and weight. I would like to hit 700 hp between 6400-6800 and redline at 7200. I wish someone would make new ones, they are essentially a 5140 I - beam at the stock 390 size. Is there anyone who is doing that? U on used rods you don’t know how many and most importantly cycles they are in their lifespan, like bending a paper clip. It will break after x cycles with x force. Thank you very much!
H beam is stronger than I beam. Didn't know that. According to what I've read in high boost applications I beams are the way to go
Yes TY
Awesome Video & Content ~ Curious if you have a LS7 Panki Ti Rods Guru ? Building a 416 Stroker w LS7 Crank & COPO Camaro TI LS7 Rods into an 80's series Land Cruiser. ~ Gen II Panki Rods have a CrN Coating radial Strip on Side Thrust surface, but the GM LS7 Crank doesnt have Full 360 Degree ~ (Short side casting void) Surface area that keeps Thrust Oiling to Full Diameter of Coating ? Seems TI Rod Guru's seem to think opening up Wrist Pin Clearance from .0006 closer to .0012 to .0018 max help let Rod Float without Side Loads, then make sure Rod to Rod clearance .008 to .010 ~ Love the Full Thrust Surfaces on Aftermarket Cranks, But the Radius become an Issue. The LS7 Crank & TI Rod 4.00 Stroke combo clear Piston Shirts & Casting in LS3 Block without and clearancing grinding, and Full Width Bearings are a Plus. If You guys ever get an GM LS7 Crank that has Full Casting Coverage, I'd Love to replace mine ~ Just OCD about reducing any Chance of Side Loading those TI Rods coatings to a Casting Sharp Edge ?
What I am concerned about is that the loaded cycle intake, compression and combustion is cushioned by the charge as the piston at TDC cushions the yank on the pistons, and rods. Power as it combusts at the bottom and the exhaust valve opens it gets within 30 degrees BTDC exhaust to TDC, there is a period where the pressure unloads and the pistons and rods are compressing an empty chamber or detonation that is sending harsh intermittent waves to the rod during overlap and at thrust can break a rod or a bolt. spike to temperature and hole a piston. Turbocharging is a very good cushion, but I have slowed down the exhaust by smaller exhaust valves like 2.19/1.6 and getting the exhaust to only flow 65-68 percent of the intake and run the cam straight up to have a greater force of pulling in the intake charge with a much stronger velocity. Like 110/110 instead of 106/110. You can pull more air and a stronger signal to the carb than what your static 28 in bench flow because of the large intake valve and the velocity. I also have used V- grooves to evacuate the air/ fuel that can centrifuge out of the mixture and create end gas and pockets of combustible mixture to stay in the centrifuge of mix by the V- grooves emptying the quench. It s usually just in the valley side crevice and the smack of a good tight squish can force the whole valley side of the chamber to rush the slow area into the main mix centrifuge prevents detonation and the rod and piston yank on the exhaust stroke and at least be strong enough to get through the short empty period with no detonation waves that cause overlap to cause interference in pulling new mixture in and keeps the centrifuge from forming.
So I want strong enough rods that are light . I want as little extra weight as possible. An FE at 428 ci is perfect for reciprocal weight and strength.
2 years later, A tank of gas to run the engine cost more then building the engine LOL