I want to run 20lbs on a gigantic turbo! Callies DragonSlayer crank, Comp Star rods... and possibly Diamond Pistons. But if I wanted to run more then the designated 18lbs that is suggested by Diamond... what could I go with?

 

I know they reccomend 18 as max, but seriously, there are lots of stock cars like eagle talons that dont even have high quality internals that can easily hold 18 psi. Ive got the exact setup you have and will prob going with a large turbo next year and hope to do the same. lemme know what happens

 

I am not building it... Nick from VRE is. But the build is a little ways away so I don't want to bother him with questions that aren't certain.

And I do know a little bit about FI... I am just trying to learn more. So please keep your comments out of here if you have nothing of importance to say.

 

Dont forget...18psi on a Talon (with say a 14g or 16g turbo) is going to be much differnet than say a t-76 on 18psi...theres alot more square inch in the turbo and in the engine...so the bigger the turbo the less boost you need to run to get to your desired HP level.

 

You're better off calling JE, Ross, or Venolia to build a set of pistons for your application if you intend to run that much boost.

 

I would suggest JE.... but i dont know anythink about Diamond. In all honestly I would say it is a good enough question to bring up to Nick. If you told him what your intentions are with the motor im sure he has adressed any issues. They know their stuff.

 

Ask BigRick.... he was pushing ~1250rwhp at 24psi with an LT1.

 

With that much boost, you'll want a forged piston made from 2618 alloy.
The 4032 alloy is normally used in NA and very mild boost applications. The 2618 alloy will be noisier on startup and may exhibit slightly higher oil consumption but is far superior in strength. JE Extreme Duty pistons are made from 2618 alloy. Not familiar with Diamonds but I'm sure they have something comparable. The JEs also have a D-cup which is better for quench.

 

>you could always go with http://www.cppistons.com/

 

I agree with the 2618 forgings, but I will say this.. it doesn't matter the make of the piston as far as having a setup tuned poorly... JE, Ross, Diamond, SRP, TRW, SpeedPro, cosowrth, Venolia... ALL of them will fail if it is not properly tuned and detonates. a forged piston will afford you a few more mistakes then cast piston due to their suprerior strength but in the end no piston is a good failsafe.

that being said.. I have been beating my TRW/Speedpro 4032 pistons with 23 poiunds of boost on 110 leaded race fuel and a tune that is very safe and I am pleased to say they have handled it well. granted I am not pushing the power some of these other engines on here are due to my stock cam and unported heads. I suppose the real question is not boost... but power output.. we all know that airflow is what gets power and it is a good indicator of boost pressures but I imagine the same 23psi of boost on a set of ported castings and a better camshaft would yield 20-30% more power meaning that the pistons will see the same abuse from 23psi as my setup sits as it would from 14-15 psi on the new bigger cam and ported heads setup.

the piston manufacturers are most likely saying that if the crown of the piston is truly seeing the boost pressure registering on your gauge.. you are moving a majority of the air into the chamber... you are setup up perfectly! mine is probably seeing a pressure drop from the intake to the cylinder from a restriction in cam and heads.

I have followed Engineer mike through his semi repeating tests of pistons and think he is finally considering or has decided to try another piston manufacturer. I am in the process of another shortblock build and am weighing my options as well.. I from his EXPERIENCE am not 100% on the JE shelf pistons and am looking more towards either a Ross or a Diamond set.

we have run JE pistons on NA setups and they do very well, and ross as well with no failures up to 500rwhp from some nasty NA setups.. but once you start pushing it with boost I think the ball game changes drastically.

My thoughts on the matter are as simple as this... if you know you are going to run extremely elevated boost pressures on a well designed and high flow setup.. you should consider dropping your compression lower then most here normally do... after all.. if you are adding that much more air to the engine.. your dynamic compression ratio is going to be higher.. you are altering the amount of volume in the bore at TDC.. this volume is housing all the extra air your pushing in.. and if you start cramping it into an ultra confined space you start heating it up and elevating EGT's.. now don't mistake my thoughts here.. a street driven multipurpose build should consider a good trade off of boost and compression ratio to keep off boost power available fro everyday driving.. but if this is a purpose built race engine.. drop the static compression ratio.. add some more room then fill it up tighter with more boost. and raise your dynamic compression ratio with more air then before.. this will yield more power.

I am dropping mine to around 8.0:1 and plan on running 20+ psi of boost regularly on 110 leaded race fuel since the cost of it locally is only a $1.00 more then 93 pump gas. but again I drive this car once a week or at the track and when I pull it out of the garage.. it has a purpose.

Chris

 

Chris the Diamond piston off the shelf is reccomended to 18psi.

For your build we will design a custom piston from 2618 material. Dish shape, skirt profile, pin location, pin oilers, etc. Will all be looked at and designed specifically for your needs.

For the record, I've seen Diamonds hold up to gobs of power in SBC applications both LT1 and LS1, well over 1500hp. In my opinion they are one of the best if not the best piston manufacturer out there.

 

Chris if it matters VRE built my 383 shortblock for my LE AFR, D1SC motor and we decided to use the Diamonds over the JE if that tells you anything.
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Also, Bigrick was using a custom Wiseco Pistons (Coated) and they only tested it to run on 15lbs. As far as I know they never ran the car at 25lbs.

 

Nah... I know enough to have an idea of what I want.

I will drive this car NOT DAILY but a lot. Power goals are 600-650whp on pump and the most I can get on race gas. Hopefully somewhere around 900-1000whp!

Street manners really don't bother me. haha

 

They did, at 24psi, and made 1240rwhp.... 1050rwhp at 15-16psi. The car was never run down the track at full boost. There was much more in that car than a 8.08 (that run wasn't with full boost). Don't let the dyno numbers fool you though, this car was turning some mean RPM so it could really utilize good gearing.

I want to get into the running for the fastest LT1... but i'm working on starting a business right now so it'll be a few years before I can put the $$$ where the rubber meets asphalt.

Sorry for getting side-tracked.... as before, I'd use the same pistons Rick used b/c they're proven.