compression on lsx blower motors

[zo66]

i would like to here some opinions on the compression for supercharged lsx blower motors,am trying to make 650 plus to the rears with a d1sc and intercooler,what should i shoot for?

[camcojb]

i would like to here some opinions on the compression for supercharged lsx blower motors,am trying to make 650 plus to the rears with a d1sc and intercooler,what should i shoot for?

9:1 or so would work very well with the D1SC, up to 9.4 or so.

Jody

[Cheatin'Chad]

This is heavily dependent on your camshaft selection and what fuel you would prefer to use.
For good pump gas and a shelf cam intended for a blower I'd say 9:1 is a barely on the high side.If your tune is rock solid you'd have no problems though.
Remember though you have to mind your Dynamic compression ratio. I'd consult your camshaft vendor if I were you.

[camcojb]

9:1 is pretty conservative for a pump gas all aluminum efi engine. Not considered high at all. I ran 16 psi with an aluminum 468 on 91 octane with a true 9.7:1 compression, no intercooler.

650 rwhp is pretty easy to attain with that engine and good heads. You can drop into the mid to high 8 range for compression if you want. Virtually all the centrifugal manufacturers recommend 9 to 9.5:1 compression on the street. Now if you were going for 800-1000 rwhp I would drop the compression, but not for that level of power.

Jody

[zo66]

my concern is that i might be to low 8.3 is were the motor is at will the disc make enough wind and is the procharger durable enough to run at 12psi on the street specs are

• <LI class=MsoNormal style="MARGIN: 0in 0in 0pt; COLOR: black; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; mso-list: l0 level1 lfo1; tab-stops: list .5in">JE custom forged and coated pistons <LI class=MsoNormal style="MARGIN: 0in 0in 0pt; COLOR: black; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; mso-list: l0 level1 lfo1; tab-stops: list .5in">8.3:1 Compression <LI class=MsoNormal style="MARGIN: 0in 0in 0pt; COLOR: black; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; mso-list: l0 level1 lfo1; tab-stops: list .5in">Lunati rods
• Custom blower cam
  Intake .554 lift
  Exhaust .585 lift
  Duration: 221 / 230
  116 Lobe center angle

[camcojb]

It will still run no doubt. Lower than you need which will make the cylinder a bit cool at cruise, but no problems from what I see. 12 psi should be a piece of cake with a good intercooler.

Jody

[zo66]

thanks jody
i appreciate the input

[DeltaT]

I agree with Jody - any lower than 9:1 and you lose the snappy low end and the centrfugals don't really kick in until you're over say 3500rpm. I'm running 9.6:1 on a 383 with a large intercooler and it is very responsive off idle and killer from 3500 until the cam runs out of steam around 6350. 230/236 solid roller, 112LSA which is a little tight for a blower but still making great power.

If you have any pinging at 12#, you could always add a modest meth kit.

Jim

[nitrorocket]

Go 8:1 compression, If your going to lower it, then lower it enough to make a difference. You will make more power on pumpgas with highr boost. This will allow you to run a higher boost level on pumpgas. The one point of compression might give you 20 hp, but the 2 extra psi of boost you will be running wil give you 40 hp.

I run a 8:1 compression in a stock cube LS1 with turbos, and can run 16 psi so far with no problems. You would be able to do close to the same!!