What compression ratio?
- Thread starter Evan@InglewoodTrans
- Start date
Are rods an issue on higher CR engines? I know wrist pin bearing transfer was an issue (alleviated by the pin oiling on Howards and custom Carillo's), but I would think cap walk would be an issue long before bending of aftermarket rods.
I will just say this as I am in no position to give out info that people do not want on the net. I know of two people that have bent or broke two different brands of aftermarket rods. Jarrod already said the mains won't take it. How much do you think the crank likes the added stress? Im sure there are many more of the big 3 rod companys that have recieved info on rods being bent or broke. Not all are on the net. I know that adding high compression can't help the situation either. To each his own. "there are more than one way to skin a cat" etc. I myself will stick to what i know works and go low compression.
Shit falls down hill right? If caps are an issue, theres probably some major strain on the rods. I know of very few aftermarket rods breaking, but more than one set was on high compression motors. Im most def not saying thats the cause, but it seems its just as good of an argument as saying high cr makes more power...
Bringing this back up with some good info.
I purchased a set of stock size Mahle cast race pistons with no relief but am reconsidering the stock CR based on the fact I may go a little bigger with my twin turbo set up. A little worried about hard parts now but also trying to avoid cold start, smoke at idle issues. 6 months of the year or more this truck will be starting and running below -20C.
I purchased a set of stock size Mahle cast race pistons with no relief but am reconsidering the stock CR based on the fact I may go a little bigger with my twin turbo set up. A little worried about hard parts now but also trying to avoid cold start, smoke at idle issues. 6 months of the year or more this truck will be starting and running below -20C.
Aren't lb7s over 17 stock? Would it not be as safe to slap some turbo or turbos on it then. Compared to the later years. My plans were to slap on my s475 and leave it all alone til I can fund a full build.
im at 16.5/1 and the pistons looked good when i had the heads off after 10k miles, i do run high boost as well.
I prefer to stay between 16 and 16.5 cr. High boost applications don't want or need high cr. Added life is achieved through lower cr. A lot of guys will go 15 to 15.5 cr. My feelings are that being that low is more for competition vehicles not daily drivers.
My 6.7 psd is stock at 16.2:1. It was lighting chargers great.
I have since changed cr, cam, valves, and injector nozzle angle. All of which improved the performance during staging, but had little effect on cold starts, or overall power imho.
I have since changed cr, cam, valves, and injector nozzle angle. All of which improved the performance during staging, but had little effect on cold starts, or overall power imho.
Aight I thought real hard about going sky high like my buddies drag truck. But ima keep it low this go round so I can grow into it when it goes 2.6
My truck's pistons cc'd around 14-14.5 Starts up on cold days around 30*F but is smokey for the first 1/8 of a mile. It starts fine in that kind of weather with not using the block heater and I took the intake heater out. Tuning helps it start. I wouldn't go that low again but got one heck of a deal on the pistons (FREE) 
. If I crack a piston I will go to around 15 to 1 because I don't truck pull anymore.
. If I crack a piston I will go to around 15 to 1 because I don't truck pull anymore.
Im going 15.5 in my build,was a little sceeerd about the 17.5 cr with trips and lots of fuel.Parts are just so damn expensive to do a build twice.
My oval bowls are 16:1, i'll be staying big single turbo as well. Figured 16:1 was a good happy medium.
Good choice it always seems like if you go to extreme you regret it. At 16:1 I think the resale and all around characteriatics will be more valuable than the potential gains from the extreme ends Of the compression spectrum.
I am having a hard time deciding between 16:1 or 16.5:1 will .5 cr make much of a difference on cold start up?
I was wondering that too just for future reference. Difference in twin setup vs big single?
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