Ron_Stoppable

iTrader: (1)

Ive posted a few times regarding my twin turbo build that im in the middle of currently. I carefully took the suggestions into consideration. So I decided going with a six bolt LSX block from the jump made the most sense.... still undecided on what I want to do for compression, truck will run soley on corn 24/7, its VERY plentiful in my state. ive been toying with the idea of 12:1.... definitely a street driven/ daily driver in the summer combo.... and may see some runs down the strip on weekends. I know I have a very strong foundation to build off of, just wasn't sure when you start to push your luck.. Not sure how far ill be able to take this setup. or what it is RWHP capable of. Id just love to have something that is just a complete torque monster out of the hole and performs excellently on the street. I haven't selected the CC I want on the heads yet, so that pretty much the holdup.
btw all of this will be going into a 2001 Shortcab S10 xtreme pickup truck lol


a few of the details of the build are below
-Standard deck LSX 6 Bolt (4' Stroke/4.125" Bore) 427ci
-Wiseco -8cc Flattops
-Holley highram
-Trickflow 245 Cathedral heads
-Twin Borg Warner SXE Billet 69mm turbos (73mm turbine/.88 A/r)
-417 Motorsports 2000hp Highram Air2Water Intercooler/w 12 gallon chest
-Oliver Billet I-Beam Rods
-4' Callies Dragon Slayer Crank
-E85 for fuel.......
-1.80 Straight cut Powerglide/ w ATI case and all the goodies
-PTC Converter

lmt0705

iTrader: (7)

9.5/1

ls3fox

I like high compression but 12 might be a touch much maybe 10.5 or 11 to 1

wildta

iTrader: (1)

Huron speed twin turbo gets you in the 8's ?

what motor are you going with ? I have a roller I am getting ready to build soon.

lmt0705

iTrader: (7)

I'm running a Thompson 387 lsx, don't go to big on the cubes, your better off having thicker cylinder walls and run more boost

alocker

iTrader: (10)

One thing to consider, no matter how good it performs down low it's gonna feel like a pig compared to when it's in boost. Just the nature of a turbo car. I say the happy medium would be 11-1 which should be pretty snappy out of boost. I wouldn't give up that safety net for the small gains above that.

Ratical

iTrader: (82)

Those cubes with those turbos should spool almost instantly, I don't think you need the extra compression. If you want more power just turn up the boost. Since you already bought the pistons I would go with the ~70cc chamber heads. Depending on the compression height of the pistons, gasket thickness, deck height and that bore I would think that would put you in the mid to high 10's on compression which should be more than enough.

asubennett

iTrader: (6)

10.5:1...Anything higher and tuning window gets small, even on corn. Allow yourself some safety margin. That's my .02

I also agree, shorten your stroke, keep the bore size down for your turbo deal, those things will light off quickly.

hellbents10

iTrader: (10)

Fuel type and camshaft should be considered when picking a static compression ratio.

asubennett

iTrader: (6)

He said corn

DavidBoren

He said he is solely burning corn for fuel, and it looks as though the 4" Callies DragonSlayer crank is already listed, as well. The question seemed to be specifically about compression ratios, doesn't look like he ever asked anyone if they thought he should change the displacement. It is cute that everyone values their own opinions so much that they answer questions he never asked.

Sounds like a great build, sir. I wouldn't go above 11:1 static compression, just for the sake of easier and safer tuning.

Ron_Stoppable

iTrader: (1)

I settled on a set of ~70cc Chambered 245 Six bolt heads. According to the calculator compression should still be around 10.8:1

vinceI

iTrader: (5)

I have a 440 with mast heads, big solid roller and twin 7675 precisions. My compression is 11.3:1. I bought the engine used so I threw a slightly thicker head gasket in it to drop it from the 11.7 it was. If I was to buy pistons I would probably be shooting for 10 to 10.5 but if your getting good e85 where you live I wouldn't be to concerned about the 11+ to 1.

tblentrprz

Bents, what would you target for dynamic compression on corn at 25psi with OP bore/stroke combo? How would smaller bore or stroke influence target?

Based on OPs parts and guessing 6.275" rod and cam with IVC 35*ABDC
Static compression ratio of 10.8:1.
Effective stroke is 3.74 inches.
Your dynamic compression ratio is 10.06:1 .
Your dynamic cranking pressure is 214.60 PSI.
Your effective boost compression ratio, reflecting static c.r., cam timing, 500' altitude, and boost of 25 PSI is 27.17 :1.
V/P (Volume to Pressure Index) is 257

Thank You

Ratical

iTrader: (82)

Good choice.

I hope that truck is tubbed!

Ron_Stoppable

iTrader: (1)

Thanks lol, a little offtopic but... would any of you guys see a problem with running ONLY a belt driven aeromotive fuel pump with my setup. Wasn't sure how streetable that type of pump would be. Btw truck will just be on some regular ole 275/60s 15x10s lol just a street truck haha

vinceI

iTrader: (5)

You could use the waterman setup that has the belt drive a cable that then drives the mechanical pump in the rear. I personally wouldn't run a block mounted belt driven pump on a street car unless the fuel cell was up front.

TURBOLSBIRD

iTrader: (5)

I built a 416 with 10.5:1 compression with 255 cnc heads. i wouldn't get over 11:1

pantera_efi

iTrader: (1)

Would you be able to find E-95 Bus Fuel in your area ?

This is a pump fuel made for high compression turbosupercharged engines.

You may ask if E-95 is available in your area.

This would allow you to use your stated pistons.

Lance

DavidBoren

Pantera, please explain why he would need E95 to use the pistons he has.

His pistons, combined with the 70cc combustion chamber heads he ordered, give him a static compression ratio of ~10.8:1 (according to post #12)... that should be just about perfect for E85 and twins. Sure, E95 would be better, but it is not necessary for him to use the pistons he has.