Was wondering what sort of hp...can stock lt1 connecting rods handle..Ive heard various things about them..that they can easily handle in excess of 500 hp at the motor..some say they cant....Im building up a 355 lt1 with a ati 8psi p600b supercharger..Im hoping to have 500 to 550 at the motor...if...they wont handle the power or just to be safe..id appreciate input on what rods to get and from where thanks for the help




Steve

 

I been running a p600b for many years now on my ride and no issues with the rods. I just freshened up my motor with a forged pistons and was going to the 355 route but as it turned out even with 114,000 miles on the clock the block was still within factory new specs(got to hand it to the guy's at Mobil), so just got the block honed. But back to the subject, and when I looked at the stock rods they were fine. I just slapped on the new forged pistons got the heads also freshened up and now back on the road. I run from 7-10psi. I do know that the stock rods are stronger than the legendary "pink" rods of old. Just my two cents. But I would also tell if you don't have to go .30 over don't, it saves for another rebuild a couple of years down the road. To many people just go right to .30 over when it is not always needed. I just checked all the bores on mine as was pleasently suprised. In any case I hope this helps.

 

ATMINF it does help..unfortunately..im already in the motor...went .30 over... scat 9000 series crank,srp pistons and rings, hotcam kit.without the cam... comp cams 7-305 cam. comp cams pushrods...runnin 8 lbs ati boost,3 angle valve job on heads..asm 1 3/4 headers flowmaster catback random tech stainless y pipe msd6al ,3.73 gears.. and a 6 speed...that about sums it up heh...just wondering if the rods be ok with the setup ..thanks for the input....


Steve

 

There was a long thread a month or so ago about the hp limits of various drivetrain parts. If you could find it, that might be helpful.

The relevance is a point that I and a number of others made. Basically, it's that you can't specify a certain hp level as the limit for a given part. The closer you get to the the absolute yield strength of a part, the sooner it will break. Eventually, after a number of stress cycles, the part will weaken and eventually fail. IOW, it's stress over time which causes fatigue, weakening of the part, and eventual failure. The stresses on a connecting rod with a 500hp setup will not exceed the yield strength of a set of new set of stock rods the first time you drive it. Eventually, they will fail.

So, in your hypothetical 500hp motor a set of stock rods might last essentially forever if you never ran near the redline at WOT. The faster and harder you run it, the sooner they will break. How long a service life constitutes "easily handle"? There's no easy answer to this, because we don't know your definition of acceptable longevity or how you will drive it.

All that aside, given typical use, I would not put a set of stock rods in a 500hp motor. When a rod goes, it usually takes a lot of other stuff with it. OTOH, I am using a set of rods that many would consider inadequate for my setup. They're Lunati Pro-Mod rods in a 700+rwhp motor. They have been in for two years, 9,000 miles, and have been used pretty hard though I don't rev very high. I put them back in this year, albeit with new rod bolts. I have my fingers crossed, but it wouldn't be a disaster if they failed, just a chance to upgrade.

Don't mean to babble on, just trying to help and get across that there is no simple yes/no answer. Also keep in mind you can get a better set of rods without spending a fortune. The Pro-Mods are in the $700 range. Many people like the Eagle H-beams at ~$500. Scat makes some nice moderate price rods as well.

Rich Krause

 

rich thanks for the input and advice.i guiess if i supply some more info it help.the car had 40k miles of which 15k or so were on the blower.the car was..a daily driver.i didnt make a habit of beating on it hard alot because it was a daily driver.im just trying to figure out..if new rods..are necessary...ive looked at the eagle h beams and have found them for a cheapest price of 450.00 bucks at racenet.being that im not a mechanic and this is my first rebuild, i just wanted to get as much understanding as i could about where i could cut a corner and were i cant.a yr or 2 ago i would of just bought new rods.but my funds are a bit limited these days and i want to get the car on the road with as little cash as possible without jepordizing the strength of the motor right off the bat..thanks for your time



Steve

 

If you want to run the stock rods, take the time to polish the beams, add some good ARP bolts, and get them resized. I am running a set done like this in a 383 with a 250 shot that has been together for about 3 years. He tries to stay under 6500 rpm but has been past a couple times...
Or, you can pickup a set of 4340 h-beams for $319 from Powerhouse products.
Your money, your choice.

 

Personally I wouldn't go with stock rods if your trying for 500-550 hp, After I tore down my 355 that had about 450- 475 rwhp my stock rods had been twisting tearing up the bearings and the stock crank was cracked. If your gonna do the motor anyway spend a few extra bucks on some better rods and then no worries.

 

rcf925 thanks for the input i just ordered some eagle 4340 hbeam connecting rods off of ebay for 389.00 shipped.so i took care of that problem i hope lol




Steve

 

Good price on the eagles... I'm not sure how much it costs to have the stock rods reworked, but by the time you do that and upgrade the bolts i'd imagine you'd be halfway there for the entry level forged ones. So, Unless you're on an extreme budget, that few extra hundred should provide some peace of mind, as well as giving you the option of adding more boost later on down the line when you get bored.

 

timbrss thanks for the input...i just want to say this site is the bomb...had to get that out heh....ive posted like a madman for the last few days..because my project is finally starting to come together..this has been a huge learning curve for me.....the only rock left unturned and i posted earlier was my cam.... its a 07-305-08 i think comp cams...its a rather mild cam..suggested to me by comp cams...im not sure if i should go with something more radical or not..or just use the cam and hope it works out well with my setup..again thanks to everyone thats posted to help me along.. i couldnt have gotten this rolling without the help......





Steve

 

Sounds like you had some serious detonation issues if you cracked the crank, and I have no idea how you would twist a connecting rod. I have bent them in the plane that they operate in, but unless the piston hit the head, of something came apart and binded up the rod, I don't see how that is possible.

Of course, this IS the internet, and there are lots of 9 sec Vipers.. so anything is possible!!

 

you mention finding a place to cut corners, rods would not be one. If a rod fails, it can take your whole motor out. Id say the best place to cut the corners is the crank.

 

Steve: two proven "blower" HR cams for an LT1.

CC XE #3190/3192 on a 114lsa. 214/224 @ 0.050" .530/.567"
CC XE #3192/3196 on a 116LSA 224/236 @ 0.050" .567/.585"

Both will need a good set of springs, pushrods, and rockers as the lobes are quite steep, actually as steep as a mild SR lobe.

The 503 cam does not have enough exhaust duration relative to intake fo a blower car.

Rich Krause

 

I lost a rod this past weekend.. Bolt on's only.. Seems like the rod bolt failed.. But the motor had 150K on it.. SO it served its purpose for a good while..

 

so rich whats the difference between the 2 cams..which is more streetable. the car ..will...er i think be a daily driver from april..to september etc. i dont need that few extra hp in sacrafice for streetability..etc... thanks for your time








Steve