Barefoot

iTrader: (1)

I have been running about 14 psi daily on my completely stock ls1 with a masterpower gt45 turbo, but I am looking to be able to run more on pump and the ability to run much more on race gas. From what I understand the best brand piston for boost is a wiseco? Not sure how much truth there is to that though. I was looking to lower the compression to about 9:1, any thoughts about this being too high/low? I am also having a hard time figuring the compression ratio for most the pistons out there, any help with this? I understand how to calculate the ratio, but have had a few issues figuring out the correct numbers to use in the calculation.

As far as the rods go, how necessary are they? What is the best route as far as strength and price? Any advice on rod length?

95maroz28

iTrader: (21)

how long you been running on 14psi? sorry no help

BIGSRTURBO

iTrader: (2)

Geez 14psi on a gt45 with stock bottom end is steep!! Hope u have a juicy front mount and some meth or e85!!!

Texhotrod593

iTrader: (7)

Ok I am personally a little lost here. It is very hard to keep a stock bottom end ls1 together at 14psi!
My questions to you are:
What displacement are you looking for(wanting to keep your ls1 block or not)? What psi are you looking for?,
What power goals are you looking for?,
Is it strictly used for street, strip, or both?
To answer you question about wiseco, I have never used them but there are very many people running them with little to no problems. I run a diamond piston and never have had problems with them personally. There are a few rods out there..one being a stock replacement(6.100 length w/.945"pin) or common what most use the 6.125 length w/.927" pin(recommended)
Compression is more on the factor of my 4th initial question. 9.2-9.6 is very common for mainly street duty. 8.3-15.0 covers for racing(of course use alcohol or similar for the higher compression ratio). Answer the questions above and maybe some of us can help a little better. Good luck

Barefoot

iTrader: (1)

I have been running 14 psi daily for over a year now with no issues, and I run WOT daily. I am fine with stock displacement, and would rather keep a stock bore. I would like to be able to run ~20 psi on pump gas if reasonable without have to go as low as 8:1 compression. As far a power, I don't care for dyno numbers, but low 10's / high 9's in the quarter would be nice. I currently run 11.05 @ 135 on the stock setup. This is a mostly street car that will go to the track a few times a year.

Texhotrod593

iTrader: (7)

I believe Wiseco will leave you around a 3.905- 3.908 bore leaving you around a 347-348 ci. You will more than likely have to at least hone the cylinders from their original 3.898 bore. I would say to stay around 9.2 compression and run meth for protection if running pump gas. Its a street machine so I would try and stay out of the 8.0-1 compression area. it would be like a dog that low and out of boost. properly built 348 at 20psi would net close to 900-1000 hp... i dont think you will have any problem dipping in the 9's with 20lbs.
Do it right the first time and o-ring the block, prep the head right and you should be able to run that all day long.
try wiseco pistons dished maybe around -10cc(depending on what cylinder cc combustion chamber you will be using)
h-beam rods(6.125)=/ .927)
micropolish your stock crank
Try using a good head with a thick deck surface(to keep it from lifting so bad) I.E. AFR, TFS, etc..
You will be golden
Good luck

Barefoot

iTrader: (1)

I am having a hard time trying to find pistons that will put me in the 9.0-9.2:1 compression ratio. I found Diamond pistons that have -8.6 Dish/3.905" BORE / 3.622" Stroke / 6.125" Rod, but from what I can figure that only puts me at ~9.7:1 compression which I think is a little high.

I also found DSS racing pistons, which I have heard very little about that have -15cc, Dish, 3.905 Bore/6.125 Rod/3.622 stroke 9.0:1 at 64cc

Does anyone have any input for these pistons or a part number for Wiseco/Diamond pistons that put me at ~9:1 compression ratio with 3.898-3.905 bore, 6.125 Rod length, and 3.622 Stroke?

ZexGX

iTrader: (28)

The only P/N I have found for low compression off-the-shelf Diamond pistons that work in a virtually stock bore (3.905) are the 11503 pistons (-8.6cc ones that you posted). That said, you can get them to custom make you some pistons. Avg price is about $120 per piston.

For my 700HP 347 build I spec'd out ARP head/main studs (clamping force is key), 3.905 bore for 11503 pistons, SCAT 6612520A (or better) 6.125 connecting rods (to match the pistons). I found another person who was selling a forged 347 shortblock with the exact components that I am using in my build, and he said he had it at around 700RWHP on a Mustang dyno at 15PSI (no other info like cam, compressor, transmission, etc.).

As stated above, you will probably be better off using the Wiseco pistons (may as well get them coated), some Lunati 6.125" connecting rods (rated for 1250HP) or strong H-beam connecting rods, and having the block machined for O-rings.

Barefoot

iTrader: (1)

No input on these DSS Racing pistons? If they are a good part, it would be much cheaper to get them @ 9:1 off the shelf as opposed to ordering some custom pistons! other than that, All I can find are Wiseco K392X3905 pistons which are a -25cc dish 8.6:1 @ 65cc

Also, how are Eagle rods (ESP 4340 Forged Connecting Rods) and Crower Rods? Its the same material as the Lunati, but much cheaper..

ZexGX

iTrader: (28)

Haven't heard of DSS pistons, but I'm no expert...

From what I've read, Eagle and SCAT rods are made in the same place, with the same materials, but the SCAT rods have better machining work done to them.

PREDATOR-Z

I'm partial to Wiseco slugs with Hellfire rings. Rods are better matched to pistons as a set.

Sales4@Texas-Speed

iTrader: (4)

I would run a wiseco piston set with thier GFX rings and a callies compstar 6.125" rod. That setup with a ARP mainstud kit in the bottom end would have you taken care of for awhile.

Texhotrod593

iTrader: (7)

^^^ I 2nd that! I was going to post that as my opinion

nodrok

If your building the engine yourself. Order your parts from a vender on the site and they will be more than happy to help you get your parts and give good idea of what your end result will be. As they have done tons of engines like yours. And you may save some money on parts as they can buy them cheaper than we normally can. IMO

swift700

iTrader: (3)

I'm going with 3.905 CP Bullet pistons. I've heard they're very strong and they have a -18.2cc dish. They might help your compression ratio.

Texhotrod593

iTrader: (7)

It sounds like he will be using a head around 64cc...-18.2 is a lot on a 3.905. That will leave him in the 8's-1 compression which I believe he wanted to stay away from.

cadivette

iTrader: (1)

I found a nifty web site with a CR calculator...

http://www.csgnetwork.com/compcalc.html

Also, here is a Wiseco with -11cc dish in that would put you at about 9.3 to 1 depending on the head gaskets you use.

http://www.texas-speed.com/shop/item...d=963&catid=38

ZexGX

iTrader: (28)

That calculator helps a lot (assuming it's accurate):

Using it, I determined with:
3.905 bore
3.622 stroke
3.937 head gasket bore
0.051 head gasket thickness (stock thickness is 0.052)
66.67 combustion chamber cc (stock 241 heads)
-8.6cc pistons
-0.007 piston deck clearance (stock recommended)

That calculates out to a 9.45:1 SCR.
This is using stock CC heads, stock crank, 0.001" thinner than stock headgaskets, and the Diamond Racing 11503 pistons. The only variable that could throw it off is the final piston to deck height, because I haven't gotten that far in my build yet to see what the clearance actually is.

Modifying the head CC to 64 and the piston CC to -11 results in a ~9.2:1 SCR

Texhotrod593

iTrader: (7)

I am thinking you mean comp. height...I have the 11503's currently installed and the comp height shows on the card as 1.314". I hope this helps

ZexGX

iTrader: (28)

"Enter Piston Deck Clearance Negative If ABOVE Deck (Use '-') : "
It asks for piston deck clearance... For an LS1, it should be sitting just a hair above the deck when the rotating assembly is installed. If it sits 1.314" above the deck surface then you must have some pretty interesting cylinder heads...