Ragtop 99

iTrader: (7)

I was talking with Chris Pippy and he observed that it seems like the XE-R cammed cars are showing peak HP at lower rpms then we anticipated.

For example my car with a 224/224 114 peaked at 6100 rpm (locked converter). I would have guessed 6300 with a 114 LSA.

Do others concur with this observation?

Trevor @ Texas Speed & Perf.

iTrader: (3)

How many degrees of advance do you have ground in? My 224/224/112 LSA XE-R peaked at 6,550 with 2 degrees ground in. It's pretty flat from 6300-6800, but the actual peak is 6550.

Pro Stock John

iTrader: (34)

Trevor is that with the converter locked?

Ragtop 99

iTrader: (7)

Trevor:
I think it is 2 degrees but I never got the cam sheet.

I am within 10 HP of peak from 5700 - 6600. <img border="0" title="" alt="[Cool]" src="gr_images/icons/cool.gif" />

If the converter isn't locked, the rpm is skewed with a high stall converter, because the dyno samples during the shift extension and computes an incorrect rpm/mph factor.
Unlocked, my dyno rpm goes 300 rpm beyond my rev limiter <img border="0" alt="[judgement]" title="" src="graemlins/gr_judge.gif" />

<small>[ August 29, 2002, 03:19 PM: Message edited by: Ragtop 99 ]</small>

Pro Stock John

iTrader: (34)

If the converter is unlocked, there would be converter slippage? So the peak HP might be moved up from where it really is?

Trevor @ Texas Speed & Perf.

iTrader: (3)

That was with the converter locked. It was at 6600 with the converter unlocked.

gator's 99TA

iTrader: (2)

my 230/230 111 LSA cam peaked at "only" 6450 rpms. i was happy with that.

also i thought with teh convertor locked "it slips" and shows a higher peak than in reality.

VINCE

iTrader: (1)

My 226 XE-R cam with 4 degrees ground in peaks below 6200rpm as well... I hit 400rwhp at 5600rpm..

Louis

iTrader: (7)

Dependant upon where you put the lobe, that will affect the peak. 2 cams that are identical, one on a 112 and the other on a 114 will have a different peak. Like the B1 and T1. Same grind, different LSA, you will find that the T1 will peak higher.

The XE-R lobe is just that, a lobe. Where you have that lobe placed (duration, Lift, advance, LSA...ect..) will determine where it peaks at.

Remember, Cylinder heads also change the peak dependant on port size, ect.

Ragtop 99

iTrader: (7)

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by G2 LS1:
<strong>The XE-R lobe is just that, a lobe. Where you have that lobe placed (duration, Lift, advance, LSA...ect..) will determine where it peaks at.
</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">That was my assumption, but I wasn't sure if the ramp rates and the shorter total duration (i.e. advertised duration of an XE-R lobe is about 4 degrees less than an XE lobe of similar duration at .050) were causing a couple hundred rpm change.

Head flow characteristics could definitely be a factor and explain why the ARE SII cars like mine perform well with bigger cams.