lt1 nitrous pistons and compression ratio

[sweetbmxrider]

Just looking for some good info on quality pistons that can take a 2-300 shot no problem. they would be for a .030 bore with a 3.75" stroke crank, not certain on rod length. Looking currently at Callies Compstar crank and rod packages.

Also, what is a desirable compression ratio for that much nitrous on an lt1? stock is 10.4-10.5:1 and i see many builds up around 11.5:1. would like to retain street manners and 93 octane. Head cc is 54 and it seems pretty tough to get the compression in the 11.0:1 range with flat tops. should i just run a cam with more overlap to bleed off some compression?

thanks for any and all info 8-)

[LTb1ow]

How big have you gone with the head gasket? Prob not the best to have a larger head gasket on a larger shot though..

What are you looking to spend on pistons?

[sweetbmxrider]

i was computing with .040 since the block will be zero decked but am open to opinions as always.

under a grand :D

[JerzLT1]

Nitrous likes higher compression

[sweetbmxrider]

but with a larger shot you can run into detonation issues, no?

[JerzLT1]

ask bill, he runs a 300

[sweetbmxrider]

yeah haha been meaning to talk to him and his mechanic

[LTb1ow]

but with a larger shot you can run into detonation issues, no?

You could run a fuel cell with 110 or higher in it for your nitrous.

And you are stuck with zero decking it or is that what you want to do?

[sweetbmxrider]

You could run a fuel cell with 110 or higher in it for your nitrous.

And you are stuck with zero decking it or is that what you want to do?

very true and the block will need to be inspected first but i am most certain it was zero decked in its previous life.

[LTb1ow]

Custom pistons. :)

Or try to bleed some CR off with cam, but thats all complicated and what not. Who did you plan on getting a cam from? Off shelf?

[sweetbmxrider]

le speced :wink: this isn't amateur hour, is it?

so who would you recommend piston wise?

[LTb1ow]

JE/Diamond/Wiseco (sp?)

TRW maybe, be cool like me, and rock speed pros?

:)

[S.J.SLEEPER]

nitrous likes compression, its all about the fuel/octane & supply. along with where the ringlands are located @ & there gap.

the larger the shot the lower the rings should sit on the piston to reduce the chance of meltin along with the ring gap needs to be larger.

i ran 12:1 compresion 383 stroker with ringlands set at 450thnds down and gap set @ 28-30thnds.
pushed a 350hp shot via direct port inj.

also you don't want the nos to come on til about 3600-4000rpms
otherwise you could rattle the motor

[S.J.SLEEPER]

oh.... also ran a seperate fuel cell & pump w/116octane for the fuel side of the nitrous

[WildBillyT]

JE/Diamond/Wiseco (sp?)

TRW maybe, be cool like me, and rock speed pros?

:)

TRW's are heavy. JE, Diamond, Venolia (heh).

[Stupercharged]

I vote JE's they're a little pricey but you get what you pay for, I had diamonds in my little grandprix and I was running a hair lean and the baster** shrunk on me

[sweetbmxrider]

yeah i was looking at the JE's, they seem quite nice.

nitrous likes compression, its all about the fuel/octane & supply. along with where the ringlands are located @ & there gap.

the larger the shot the lower the rings should sit on the piston to reduce the chance of meltin along with the ring gap needs to be larger.

i ran 12:1 compresion 383 stroker with ringlands set at 450thnds down and gap set @ 28-30thnds.
pushed a 350hp shot via direct port inj.

also you don't want the nos to come on til about 3600-4000rpms
otherwise you could rattle the motor

i have a window switch for the last part. was kinda thinking about a standalone, but at the same time it seems like it could be a little excessive. if i go direct port then yes. if i don't and only do a nitro dave's plate which is what i'm really leaning towards, then i would want to stay with a line from the fuel rail.

[LTb1ow]

Pulling fuel for a 200 shot off the stock rail and lines may be risky man.

Relocate your battery and run a N20 outlet fuel cell up there. Very nice stuff.

[sweetbmxrider]

yeah it does look good. you're killing me though :lol:

[LTb1ow]

http://www.yellowbullet.com/forum/showthread.php?t=181436

Granted a lot of those motors are strict race motors but some of those guys are running pretty tall head gaskets and large nitrous shots. That thread though is for aluminum rods and I assume making sure the stretch they experience won't cause PTV issues.

Also, not sure on ring gap for nitrous being good for DD dutys...

O ring your block. :)

[sweetbmxrider]

yeah its not really going to be dded, just takin out on nice days and meets. thanks for the link though.

[LTb1ow]

Have you talked to Lloyd yet about your cam?

I would get that figured out, kinda important and linked to your piston choice and what not.


And you should run Jesels. :)

[1984camaroz28]

11.5 to 1

Pulling Fuel off the rail on a large shot is a time bomb

U can run a Stand alone for ur n2o and run some c16 in it. Pump Gas is going to really limit the power potential

[transmaro93]

haha 300shot??? your crazy dude.... this car should never see the streets... i wouldnt sacrifice compression by fudging with the cam specs... seems kind of redundant to me and you wouldn't be using the motors full potential.... 53cc is a little tight with a flat top... my heads are 63cc chambers and my CR is like 11.0:1 not sure what gastket they used... but probably what ever standard is... my block is zero decked also... its not a daily so if you have to run race fuel in it or a mix so what... its not like your filling it up every 4 days...did you ever look into those coated mahle pistons...they are pretty affordable and are supposed to work really well with nitrous... you are going to have to do some major fuel upgrade too man.. i dont know much about the nitro stuff but i know that the little 255 through the stock lines probably isnt going to be enough to fuel that motor plus a 300 shot... i cant wait to see your build sheet when your done to compare it to mine... becuase iv spent god awful loads of money so far... and your goin the distance ahah... just a forwarning... it sucks when you spend a ****load of money like i have right now and its not even running... so dont get discouraged from that... and i have a o2 sensor extention if you need it... i didnt end up needing the one i had... ill prob have other crap too left over that you maybe can use... but nothing you will need anytime soon...... **** THIS WEATHER I WANT TO START MY CAR!!!!!!!!!!!!!!!!!!!!!!!!!! well talk more toamarrrow night at the meet..

[S.J.SLEEPER]

if you plan on going w/ a 300 shot. you better plan on gettin a nitrous controller while your at it, along w/ seperate cell,pump, etc... like me and 1984camaroz28 said above

probe & mahle pistons are pretty nice and aren't too expensive.

[sweetbmxrider]

alright thanks guys

back to the drawing board

[Pampered-Z]

alright thanks guys

back to the drawing board

Just take your time and figure everything out first. You're going to need to do allot of research before you start figuring out all the pieces. Good time to grab a few books about SBC/Nitris systems.

One thing I'll throw out is having two ECMs for the car, one with and one without Nitris. I don't think trying to trick the ECM with some type of timing retard box etc is going to be the way to go for your engine. A Nitris hit that big is going to need it's own tune. Or if you have the budget, go aftermarket. With a shot that big you are certainly looking at a major investment. Also another option is running 2 stages.

Look at this car:

http://www.injuneer.com/mod.php

Injuneer ran a 125 primary and 150 secondary shot when the car was on the street, when he went towards more of a strip car he converted the system into a single shot.

Note that Fred's car is built (in my opinion!) right, there were no short cuts or exspense spared when he built the engine and supporting parts! You should know this engine has been together for years, LT4 heads were a hot item. Even with them he's pushing in the 800HP range, could go allot more with some of the new tech heads and such.

If you look at the pic of his "office" you can see the nitris controlers built into the door panel pocket. He can arm the system, bottle heaters, aux fuel pump (tank is sump'd with a seperate feed for the nitris). Fred also runs a Motech computer, so when he arms the nitris it signals the motech to switch to the nitris tune. Real slick setup, major $$! I based all my internals off his engine with the difference I have lower CR blower pistons and custom blower cam.

[sweetbmxrider]

that is an amazing setup :drool: he really went no expense spared


its a really tough spot i am in. i'd like to just stick a plate on there and do a 200 shot. its at the limit of the system and would be fun and simple. since i'm building the bottom end i don't wanna limit myself and would love to see what it could do with a 300 shot fogger system with dedicated fuel system. that would be much more planning, purchasing, and time down. i am going to really have to think about this because once i go big, its full commitment. thanks for the insight!

[LTb1ow]

I would guess the 200 shot will be harder on you to get it right and harder on your pistons than a DP system.

Even N20Dave was saying that 200 and higher requires a lot of tuning... playing with individual plugs and going colder/hotter etc. I would get the motor together and spray a 150 shot... nothing crazy, and you may get more than one pass off the bottle. ;)

Then start looking into DP setups.. There is a sweet sponsor over on YB that does some amazing DP setups..

[NJ Torque]

I wouldnt go any larger then a ~200 shot on a plate anyway...

[LTb1ow]

Yea... and if you do, pray those back cylinders don't go lean...

[sweetbmxrider]

no, 200 would definitely be the limit. man those dp's are nice!

i thought #1 had the biggest issues do to some casting on the stock intake?

[LTb1ow]

Its more of the plate spraying right by the front ones, and having the whole spray pattern sucked down and leaving the rear ones lean as hell.

But yea.. DP leaves lots of doors to open... two stages, three stages, three stages and a plate.... Hmnnnn

Edit: cause your lazy...
http://www.yellowbullet.com/forum/showthread.php?t=103672

Spend moaar monies!

[sweetbmxrider]

alright i see.

already skimmed through that thread :wink:

[LTb1ow]

Kinda veering off course here... but if you really wanna spray that much, you had better have a very good suspension or hello wall... and since you are leaning towards a weekend warrior car... why not cut the cowl, and run a nice SBC tall X intake. You can keep your EFI and all that but it gives you a much better intake for spraying.

[WildBillyT]

Slightly off topic, but if you do decide to do a dedicated fuel system I've got a 5gal cell with a sump that I'm not using.

[LTb1ow]

Oh boy.... don't empower him...:rofl:

[sweetbmxrider]

i'll keep that in mind.

this is too nice though :drool:

http://nitrousoutlet.com/images/products/00-12000.jpg

[LTb1ow]

http://www.ls1tech.com/forums/lt1-lt4-modifications/1031252-400-600-shot.html

http://www.fquick.com/images/vehicles/full/676148130.jpg

You did say race car right?

:)

[sweetbmxrider]

interesting thread.....

[LTb1ow]

Some pictures to set the tone of a lean shot.

http://www.yellowbullet.com/forum/showthread.php?t=3151

:) Have fun!

[sweetbmxrider]

if you plan on going w/ a 300 shot. you better plan on gettin a nitrous controller while your at it, along w/ seperate cell,pump, etc... like me and 1984camaroz28 said above

probe & mahle pistons are pretty nice and aren't too expensive.

what kind of nitrous controller did you have or would you recommend?

i got a direct port setup though on a stock lt1 intake with a stand alone fuel cell. its pretty nice. also, i have a 6al at the moment, think i should just jump to a digital 6 and call it a day?

[JerzLT1]

If you haven't ordered your pistons I would give Lloyd a call. 11:1 is great for a SBC but you should look more at going 12-12.5:1 with reverse flow cooling and aluminum heads. It will allow you to run a larger cam and make more power (bleed off some cyl pressure to keep the dcr low enough for pump gas)

[sweetbmxrider]

yeah i haven't purchased them yet. have you figured out what you will be using yet?

[JerzLT1]

PM sent

[LTb1ow]

http://www.yellowbullet.com/forum/showthread.php?t=47504


Progressive controller reading.

[sweetbmxrider]

thanks matt