Stroker Compression Ratio Calc error?

[JeepFamily]

Not sure where to best post this question? I was recently using the calculator and found a discrepancy in cam data for the OEM uses a LSA value of 114.3. Other sources including Dino's list 107.3 as the LSA and 114.3 as the ICA. Does anyone know which is correct?

[Retlaw01XJ]

I questioned that as well!
I profiled my stock 2001 cam last week and the result was 107 degree lobe separation with intake centerline at 114 degrees.....sort of.... the max lift point of the intake lobe isn't centered on the lobe, it's off center.
Apparently, they calculate the lobe centers based on open/close points at 0.004" lifter rise. That gives the 107 LSA, 114 Intake centerline and 100 exhaust centerline.
If you look at the actual max lift point of each lobe, Intake is at 109 deg and exhaust at 103 deg, then LSA is 106.

Ill be profiling my Crower cam next week. Curious how that is going to compare.

[Muad'Dib]

If the cam data is incorrect for the cam listed please be certain and then let me know... i will update the calculator with the proper data. FYI, all cams are listed with their Advertised values NOT at .050. This is for Calculator Accuracy.

[Retlaw01XJ]

The 114 Lobe separation angle listed in the calculator for the late cam is incorrect.
The cam data sheet link from Dino's page, http://www.angelfire.com/my/fan/Jeep4.0Camshafts.htm
shows a LSA of 107.3 degrees. My own measurements (used 2001 cam) gave me 107 deg, so I will confirm the 107.3 listed in Dino page.

My other measurements were generally within a degree of Dino's chart, with the exception of my 0.050" points, which were advanced 4 degrees. Strange. My lobes are lopsided.

Note.....the 'advertised' figures (for the stock cam) in the FSM and Dino's chart are at 0.004" lifter rise at the cam.
Still trying to determine if other cam manufactures use 0.004" lifter rise or 0.006" valve lift for their advertised specs.
What does the calculator use for the intake closing point? 0.004", 0.006", or is it derived from 0.050"?

[Muad'Dib]

Ok, i made the cam change...

I also added the 229AC Mopar Cam.


Let me know if anything else needs to be modified or added. Thanks

[Retlaw01XJ]

Excellent!
I'll let you know when I get some definite info on the 0.006" vs. 0.004" lifter rise on the 'advertised' timing specs.
Jeep does use 0.004" lifter rise. I still have to check with the cam companies.....

[GoMopar440]

The calculator seems to be broken. It's not inputting any of the blue linked numbers on the right over to the column on the left when you click them. The calculate button doesn't tally the total numbers at the bottom anymore either.

The last change seems to have been on Jan 18 with the addition of the 229AC Mopar cam. Did something just get switched off for editing and not get turned back on?

It was working last week for me and I haven't changed anything on my PC recently. I'm running Win 7 Pro and IE 9 if it matters.

[Muad'Dib]

The calculator seems to be broken. It's not inputting any of the blue linked numbers on the right over to the column on the left when you click them. The calculate button doesn't tally the total numbers at the bottom anymore either.

The last change seems to have been on Jan 18 with the addition of the 229AC Mopar cam. Did something just get switched off for editing and not get turned back on?

It was working last week for me and I haven't changed anything on my PC recently. I'm running Win 7 Pro and IE 9 if it matters.

SInce your running IE9 you have two options.

1.) After the Calculator page loads, refresh the page. This should fix the issues you describe.
2.) Clear your browser cache and delete all temporary Internet Files.

Please let me know if you have any issues.

[GoMopar440]

Yup, that fixed it. I opened the calculator in a new tab and then just refreshed it (F5). Works as it's suposed to now.

Thanks!

[JeepFamily]

My cam choice was between the OEM and 68-232. Couldn't get dynamic compression above 8 for the OEM prior to fix so I purchased the 232. We wanted a injection friendly cam and it now looks like both would be a good choice giving a DCR of 8.2 to 8.3 with a static compression ratio of 9.6.

[Retlaw01XJ]

The adjustment to the late cam specs included changing the intake closing point. It's now measured at 0.006" lifter rise instead of Chrysler's 0.004" spec.
The resulting DCR between the stock and Comp 232 is pretty close now.
I'll be profiling a Crower 44243 cam this weekend. Will post the results.