L31 Supercharged Vortec HP numbers?????????

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gotahoe01
Posts: 2
Joined: Tue Nov 28, 2017 1:04 pm
Location: WI

L31 Supercharged Vortec HP numbers?????????

Post by gotahoe01 »

I was just wondering was everyone was getting for RWHP on their 5.7L Vortec's? Specifically ones with mods similar to mine.

Supercharger
Cam
GM performance Heads
Snow Performance Water/Meth
Walbro fuel pump
36LB injectors
EGR/CAT delete
Elec. Fan
Ceramic shorties
MSD dist/Digital 6AL


Spent 3K at the Dyno(Had to fix a few things while there) and left with 180hp. They said I should just enjoy it. Did find out they did all the tuning with a bad torque converter, so not sure what that would do to the tune. Seems to run really rich, exhaust is super strong.

Bushwacker
Posts: 110
Joined: Wed Jul 04, 2012 4:05 pm

Post by Bushwacker »

You do mean a 180hp more after the mods right?

CrazyHoe
Posts: 6228
Joined: Tue Feb 19, 2008 8:30 am
Location: Mtl; '98 2dr4x4 Tahoe, L31,Hookers Long T, 0411,EFIlive, 4L80-E,dual 3",marine int+inj

Post by CrazyHoe »

The OEM Vortec produces about 58ft-lb per liter.

So that's 58X5.7=330ft-lb

A good performance head with higher compression ratio and good cam might give you 70ft-lb per liter.

So 70X5.7 = 400ft-lb

That's normally aspirated.

Add a supercharger and your new torque output will be the torque per liter of your engine X the volume of the supercharger divided by the volume of your engine.


If you have the 1.6L Whipple and the 3" pulley that's:

[1.6 X 7.5"(crank pulley)]÷3"= 4L

But since the engine needs 2 rotations to pump 5.7L

That will be 4L X 2 = 8L

So,

8L÷5.7L= 1.4 (or 40% more air pumped into the engine, 40% more torque)

So the stock Vortec would do

330ft-lb × 1.4 = 462ft-lb

And your performance engine would do

400ft-lb x 1.4 = 560ft-lb..... at the crank.

But because the drivetrain causes mechanical loss up to 20%.


Simply multiply crank numbers by 80%


Stock Vortec at the wheels with 3" pulley = 370ft-lb

Performance engine with 3" pulley = 448ft-lb

How many psi?

14.7psi (sea level) X 1.4 = 20.6 - 14.7 = 5.9 psi boost
Last edited by CrazyHoe on Wed Nov 29, 2017 5:58 am, edited 3 times in total.

CrazyHoe
Posts: 6228
Joined: Tue Feb 19, 2008 8:30 am
Location: Mtl; '98 2dr4x4 Tahoe, L31,Hookers Long T, 0411,EFIlive, 4L80-E,dual 3",marine int+inj

Post by CrazyHoe »

IMO that's a good approximation of the peak torque.

Hp is more complicated to calculate precicely because peak hp will vary widely and is dependant on RPM and torque output at peak hp

But let's say you have a healthy engine that produces 1hp per cid.

That would be 350hp

350hp X 1.4 = 490hp

490hp-255hp= 235hp (at the crank)

235hpX 0.80 = 188hp (at the wheels)

That's (in theory) 188hp gain over stock of course

So 180hp is good and very realistic

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