ok, some of you are familiar with the hks cams due to the dsm world and evo's no big deal. some people run this grind on the lsj as of now.

im sitting here thinking, it's a turbo cam. we have blowers. some of you need not apply for this wierd idea because this cam will work fine for you. since you're turbo now


hks 272 specs
Advertised Duration - 272 deg
Effective Duration - 214 deg @ 1mm
Lift - 10.8mm Int / 10.2mm Exh
Lobe Centerlines - 110 deg Int / 110 deg Exh
LSA - 110 deg


Inch conversion

214 deg @ .0394
lift - .426 intake
lift - .402 exhaust


now, here is my idea. s/c engines work on the same principle as any other forced induction motor, but this is where it stops. the s/c engine would work better with a scavenging affect on the exhaust side.

the more i get into this, the more i play with numbers, and various other things here and there. lemmie run this by you. taking that cam spec for the 272's, and tweak them a smidge so to speak.

Advertised Duration - 272 deg
Effective Duration - 214 deg @ 1mm
Lift - 10.8mm Int / 10.2mm Exh
Lobe Centerlines - 110 deg Int / 110 deg Exh
LSA - 112 deg


Inch conversion

214 deg @ .0394
lift - .426 intake
lift - .415 exhaust


the intake cam stays the same lift, las changes to 112 on both cams. the lift on the exhaust also increases. the centerlines stay the same.

this thread isn't for everyone. more or less a technical thread on how to improve upon a cam design, and make it work better for the lsj with the blower

 

*waits for responses*

 

I could make a killer grind, but being stuck within the confines of regrinding stockers sucks.

 

So ideally one would be changing the Lobe Seperation Angle, which would change the lift of the exhaust while leaving the intake alone?

What would it do for duration?

 

I had posted somewhere the 272 specs compared to stock. I'm curious to look at them again to see how far flow technics takes them out while regrinding.

 

That deff. sounds like a viable option Area... because blowers do react different than the snail cars!

Now the 272 grinds have proven themselves time and time again... But once again they are a turbo cam.

Interesting..........

 

yea i know, thats the delima right now. trying to get a scavenging affect out of a turbo cam isn't going to be easy. the burns stainless collector helps, but the cam would help more.

with the cams being welded we "in theory" should be able to change the lsa a tad, and increase the exhaust lift to promote better flow.

i know im not thinking out of my ass on this one, lol.

 

Some of the best ideas come from the butt! Now is doing that an option with our cams, since you are doing a regrind?

 

*grabs popcorn* Continue your smart talk so I can learn something new.

not always...

 

I priced out rewelds with one of the big companies a while back and decided against it due to downtime since I wasn't able to purchase cores from them.

I really need to find the post of the stockers compared to the 272s. brb

 

http://www.crateenginedepot.com/store/PDFS/ECS.pdf

INTAKE Cam Valve Valve Duration Valve area
Part Peak Lift Peak Lift Timing @1mm lash @1mm lash
12587985 - LSJ 5.9557 10.03790354 100 196.50 1117.70
12590699 - ’07 L61 5.9804 10.07953361 116 198.40 1112.90
12578511 - LE5 6.2551 10.54252068 135 210.30 1253.30
12589335 - LNF 6.111207 10.29999939 126 203.60 1171.30
EXHAUST Cam Valve Valve Duration Valve area
Part Peak Lift Peak Lift Timing @1mm lash @1mm lash
12584363 - LSJ 5.9504392819 -115 191.70 1076.4043 10.
12590700 - ’07 L61 5.9752 10.07918306 -108 193.30 1078.00
12578512 - LE5 5.95143 10.03908697 -125 195.40 1092.70
12589340 - LNF 6.106106 10.30000003 -120 194.00 1106.00

 

Double check mah math here but try these numbers:

Stock:
Intake Lift: 10.04 mm
Intake Duration @ 1mm: 196.50
Intake Centerline: 100 degree

Exhaust Lift: 10.04mm
Exhaust Duration @ 1mm: 191.70
Exhaust Centerline: -115 degree

Stock LSA = 112.5 degree


272 grind:
Intake Lift: 10.80 mm
Intake Duration @ 1mm: 214.00
Intake Centerline: 110 degree

Exhaust Lift: 10.20 mm
Exhaust Duration @ 1mm: 214.00
Exhaust Centerline: -110 degree

HKS 272 LSA = 110 degree

 

According to GM's specs that is right Witt! I have them in the post above... it also has the LNF cam specs too...

 

i was about to pm u about this bryan...while doing my bench flow on the head and looking things over yesterday..the 272 are too much...hell the cobalt with 1400 hp on a race motor is only running 268...i just bought some JBP stg 2 tri-flows lastnight...

the specs:

PRIMARY INTAKE
ADV 264* 418L @.050 209*

SECONDARY INTAKE
ADV 256* 417L @.050 202*


PRIMARY EXHAUST
ADV 256* 417L @.050 202*

 

Listen here smarty pants!

 

Looks like the LNF uses an LSA of 123 degrees, 120 and -126 centerlines.

 

That deff. what it looks like to me.... interesting!

 

After the 400hp mark GM used cams with 222 duration @ .050"



Courtesy of the 400-600hp build book.

 

on there NHRA car the guy said there cams are 268...truthfull or not i dont know..but its looking to me like 272 are just too much..
????

 

I was just messin' with ya Raven... you should know that!

 

i know i thought i said something wrong? i wasnt coming in to argue just wanted to throw in the JBP cam specs..also i want to add to the post that even tho they are expensive...having to have a back lash shim isnt a problem with these.

 

im thinking bring the lsa back up to 112, and drop the intake lift to 208-210.

just an idea

 

so ur gonna go mild on them? im guessing ur looking to kill 300hp?

 

Eh, he'll get his 300 I'm positive on that!

 

lol thats why i said kill...why are u talking to me?! i am mad at u...stupid stock black seats...