Thought I'd ask here too...

Reply Subscribe

Thread Tools

Search this Thread

Dec 21, 2006 | 07:49 AM

SSpdDmon

Thread Starter

TECH Addict

iTrader: (10)

Joined: Jun 2004

Posts: 2,918

Likes: 0

From: Commerce Twp, MI

Thought I'd ask here too...

https://ls1tech.com/forums/generation-iii-internal-engine/626534-want-40-ft-lbs-torque.html

Check out my post (#18).

Anyone know why we consistently see the dips in the hp/tq curves around 4,000~4,800 rpms with aftermarket cams? I'm leaning towards timing as the culprit, but have no solid answer/proof...

Dec 21, 2006 | 07:51 AM

SSpdDmon

Thread Starter

TECH Addict

iTrader: (10)

Joined: Jun 2004

Posts: 2,918

Likes: 0

From: Commerce Twp, MI

Examples:

Dec 21, 2006 | 08:33 AM

Sean Collins

The know it all's know it all

Joined: Oct 2006

Posts: 500

Likes: 0

intake Runner & cam timing dynamics.Tight LSA cams exhibit this behavoir more then the wide LSA cams at least from what i have seen but that overlap quantity is dependent on total lob timming.

Dec 21, 2006 | 08:55 AM

SSpdDmon

Thread Starter

TECH Addict

iTrader: (10)

Joined: Jun 2004

Posts: 2,918

Likes: 0

From: Commerce Twp, MI

Hey Sean...thanks for the input. Hopefully, we can chat more about this when I have you put my LS7 clutch in for me next year. That is, if 'Santa' is still bringing his 1/2.

It'd be nice to get rid of that dip in my tq curve though. I could've swore it was timing related because the guy from PA who put the car together only had ~25* of timing there. I didn't try upping it to 27* while I was on the dyno (rushed for time)...

Dec 21, 2006 | 09:18 AM

foff667

LS1TECH Sponsor

iTrader: (2)

Joined: Jul 2003

Posts: 7,986

Likes: 3

From: Clermont, FL

Yeah some have mentioned its timing/fuel related, personally I don't have access to a dyno so I havent been able to fool around with it...I would love to see someone with roadrunner or RTT toy around with things on a dyno to see whats up exactly.

Dec 21, 2006 | 09:25 AM

Sean Collins

The know it all's know it all

Joined: Oct 2006

Posts: 500

Likes: 0

Quote:

Originally Posted by foff667

Depends on the application ( i actually own a dyno a very nice one) and while with a stock engine it can be related to fueling and spark on most of the motors out there with camshafts it tends to be camhsaft intake manifold runner related. Some cams do it others don't again this can be on a case by case bassis but for the most part it tends to be related only to cam timing. If you cam timming is wrong you will have the dip if its right you won't. generally this is what i see. Engines that have the dip are down on TQ alot over engines that don't usually on the order of 20 or more lb ft and they are way down on HP to.

Reply Subscribe

Reply Share

First
Prev
1 / 1
Next
Last