Im biulding a 383 with a forged rotating assembly. I plan on spraying a 200 shot also. I need to know what length rod would be best for this app. I would like to use 6in but have heard 5.7 would be better for a nitrous app. Should I just shoot for the middle and get 5.85 .

I also plan on using SRP flatop pistons so it looks like my compression is going to be about 11:1.....should I use gapless rings?

 

These questions are better suited for LT1 Tech, moving for you...

Thanks.

 

You need to rethink your compression ratio. Once you do that then see what pistons are available with at least a 1.1 compression height. Then if you can't find the pistons reduce the rod length until you find the pistons. Remember NOS puts extreme pressures on the pistons. I recommend being below 10:1 and work from there.

don't forget where you live and octane.

 

I thought the same for a while, but then i learned that compression and nitrous work very well together. I'm going upto 12:1. Its high compression that hurts a blower stetup.

nitrous isn't compressed as a s/c or turbo air is. it just has a very high o2 composition.

I say go more compression and 6'' rods
93 will keep you from knocking with a 12:1 CR on most cars
but its dependant on other factors, particularly your cam

 

Below 10:1. I disagree. I am running 11:8 and spraying a 250 shot a few times..mostly 200shot. No problem here

 

Sure it does, they both increase cylinder pressure. But there's a limit to how much cylinder pressure the engine will tolerate before detonating.
If you're studious enough and really follow some of the big guys who've been successful with nitrous over the years you'll see that they run a little less static compression. Sam Gianino is pretty well known in the world of hard-core race engines... he builds alot of really fast nitrous cars. He runs a static CR of ~14.5:1 vs everyone elses N/A ~16.3-16.5:1. The reason is cylinder pressure. Same thing from Mike Hedgecock (Robbie Vandergriff's engine builder).
So, I'd say stay on the safer side of things but all things considered (cam timing too) I'd knock the comp down about 1/2 point or more for a serious street engine on 150+hp of nitrous. Better safe than sorry.

-Mindgame

 

Ok,

I'd stay with no longer than 5.85 for your build. 11.0:1 is also ok. I'd stay away from gapless rings... myself and the majority of racers out there have had no luck with them. Speed Pro file-fit plasma moly rings would be my first choice. Stay away from thin-wall wrist pins too.... I'd use a good taper wall tool steel pin.

My .02

-Mindgame

 

OK, this doesn't have anything to do with the post, but I was looking at the topics in the LT1 tech board when my roommate walked in, and in a sarcastic manner he said "You looking at Camaro stuff again.....What size rod should I use" I thought he was just poking fun at me, but no, this opic sure is "What size rod should I use"

Immature? Yes, but still funny

 

Mindgame, are the pins that come with the SRP pistons ok....or should I use better ones than that......any particular ones that you would recommend?

 

I will generally use Childs & Albert tool-steel wrist pins but JE makes a good taper pin too.
I don't usually use JE/SRP pistons but since you're using them... I don't see why you couldn't contact 'em and get the right wrist pin for the job. You may find that JE's "nitrous series" pistons (if that's what you're using) come with a heavy duty pin as it is... I'd imagine that's the case but I would want to know for sure. If not, I'm sure you can upgrade.

Hope this helps.

-Mindgame

 

Thanks for the input guys, I think I will go with the 5.85s and up grade the wristpins. I belive I will stick with the 11:1 compession since 99% of the time the car will be run NA.....I plan on starting out with a 100 shot and working up to a 150 shot at the track. When spraying I plan on pulling 2 * timing at 100 and 4* at 150 as well as running a 50/50 mix of 93 and 100 oct fuel. I also have Datamaster to keep an eye on knock. Anyway......I hope to run this full trim heavy ars convertable deep into the 11s

Thanks again

 

just run down to 1 or 2 gal or so left and add one gal 115 octane
spray away
if you have 2 gal of 93 thats roughly a 100 mix
your kosher


dont forget a cage with a drop top

 

hummm...dont belive you can get that in unleaded....at least not around these parts