So some people here have those 383 strokers with 6" rods and some probably built some with the stock 5.7" rod size. Both sound perfect so far and have a nice r/s ratio above 1.5.Talked to some people about the motors builds with poor r/s ratios and of course they automatically tell me that they are never meant to rev high. I feel bad for the cylinder walls of this 447 stroker motor with 5.85" rods and a whopping 4.100" inch stroke. They should name that motor the "rod snapper", "sidewall loader", or the "oval bore" motor.

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Might have gobs of torque down low, but may only last 50,000 miles or less. I bet the moment someone revs that block past 4000 rpms, a rod might pop from the sidewall and stab an innocent by-stander.

I'm afraid a 1.42 rod/stroke ratio would NOT be a kind motor to deal with in the long haul.

 

You pretty much said it. Rod stroke ratio and Hermetically Sealed clean rooms are the conversational sanctuary of those who can't port heads, pick a cam, or tune on a dyno.

 

Well, the B16A2 in a 99-00 Honda Civic Si has one of 1.745. I hear if the head is built right with stiff springs, the stock bottom end can easily take 10,000 rpms like it is nothing. Sometimes its a fact that the weak valvetrain is the main reason why some people ***k up their motors.

 

You seem to know a lot about engine building, performance and durability. What do you think of a 383 stroke crank with a 5.565" rod? Will it rev to 5000 rpms. Can the engine live?

RACE ON!!!

 

a co-worker ran the old school 383 with 5.565" rods in his 69' Nova and i was impressed with its response and lowend torque. it built up speed quick and did rev to 6000rpms. it was built with the Edlebrock RPM package and it lasted until he had a cracked block in the lifter valley,also flattend 2 lobes on the cam right before the block took a dump. had about 10,000 miles on his motor and it was pure thrash time. when we took apart the motor the KB claimer pistons he used had very little scuff wear on them. the motor probobly didn't detonate much at all from the looks of it.


put it this way....a 5.565 rod would be more ideal for the street so it doesn't have to see high rpms nearly as often at the track. 5500rpms or below on a motor every now and then isn't gonna hurt much compaired to a 6500rpms all weekend at the track. if you play on the freeway and like to stretch out your vettes legs i probobly wouldn't go with these rods due to long use at high rpms and poor rod angularity.

i'd use the 5.565 rods with ARP bolts if i had em'. if i build a 383 it isn't gonna see 6000rpms at all. maybe 5200. 2-4 track times a year and mild street driving ain't gonna hurt a 300-400hp motor unless something was set up wrong to begin with.

 

Possibly CFI-EFI, but the r/s ratio would be too low for my liking. I can't really trust motors with that type of engine geometry. I'd say anything below 1.5 is like having dynamite under the hood when you over rev it, unless the crank has been balanced perfectly. I'd take rev that 383 no further than 4500 rpms and hopefully nothing will break.

I remember when I used to work on Hondas, the low 1.5 r/s ratio of a stock 1990-2001 Integra LS engine would snap rods when taken to 8200 rpms for even a few seconds. Trust me, I have seen this happen more than once. It is a loud bang and some crunching. When you take the head off and disassemble the motor, it is not a pretty site. Yes, the fuel cut off of those little 1834 cc motors is set at a good 7200 rpms stock, but kids think they can just slap on a chip to get 50 extra horsepower. It ups the fuel cut off to 8500 rpms. Most kids who don't know any better will shift it way up there that high and later wonder why their engine just "blew up".

 

[QUOTE=k0rv3tt389]. I'd take rev that 383 no further than 4500 rpms and hopefully nothing will break.

QUOTE]

its not gonna just break like a twig unless something was machined wrong or cast improperly.the stock 400's used these rods and lived past 100,000 miles in stock applications. and thats with a siamesed cylinder block. a 350 block has more casting and will take some RPMs.

just curious whast the R/S of my 455 pontiac? 6.625" rod 4.21" stroke crank.

 

[QUOTE=SHINOBI-X]
It is 1.57. That is perfectly fine. 1.5 is the limit! All you would do is divide the rod length by the stroke of the crank.

 

I would worry less about the ratio and more about what the rod is made of and the quality. A really good set of rods will go a long way. Anyway that engine just has that specific length in it because that is all that will fit. So what would you purpose that they do? They put a decent connecting rod in it so what's the issue?

 

How about the sidewall loading? If the rods don't break, those cylinder bores are probably gonna be oval once you overhaul it in the next 10,000 miles. I'd say the wrist pins on the pistons, or even the piston skirts are probably also going to go along with that amount of stress. How about the bores shifting around from all the heat and pressure?? Sorry JMHO. I see the SAE like to put the r/s ratios above 1.5 if there are any exceptions at all.

 

1 The stress on the sidewalls comes from combustion. Sprint car engines blow out factory blocks because of the 15.1 comp and maxed out timing!
2 The cylinder bores are not going to oval because of the minimal increase in load. In 10,000 miles, PLEASE!
3 Piston wrist pins only fail due to too much timing that beats them death and eliminates their oiling ability.
4 Piston skirts get wore due to piston rock. This is an issue that deals with clearance not so much load, and again good forged pistons will eat parts of rings down the skirt and not fail.
5 Heat and pressure, again, take a look at a race engine and then you see heat and pressure, minimal amounts of it coming from the load you are talking about. Heat, it's called a cooling system, and why would it have more heat since all the heat comes from combustion anyway?
6 SAE is really just covering their you know whats, just like the ring manufacturers calling for so much gap in their rings. Talk to any race engine builder and ask him how tight he runs rings in race engines and you will be shocked, I was. Please remember that SAE deals with street crap, stuff that has cheap parts and was designed for grandpa to drive and also to make profits. Get into the racing world and find out a little of what’s going on. Plus you didn't even answer my question! What should they do? Are you willing to buy a $5000 tall deck block so you can get your ratio where you want it? I think not. The stock 400s went into a lot of vehicles that got beat and never had problems with any of these. I think I will go with experience over theory on this one. You will be very surprised when you open up a seasoned race engine and see first hand what heat and pressure inside an engine is.