Previous Thread
Next Thread
Print Thread
Page 2 of 3 1 2 3
Re: What compression would you run with a 499 stroker? [Re: challengermike] #1123610
11/29/11 12:39 AM
11/29/11 12:39 AM
Joined: Dec 2010
Posts: 392
Mississippi
lahatte Offline
enthusiast
lahatte  Offline
enthusiast

Joined: Dec 2010
Posts: 392
Mississippi
71 degrees after BDC is late for a closing, which would reduce the DCR. The cams I've looked at typically have an intake closing between about 63-67 degress ABDC.

Last edited by lahatte; 11/29/11 12:40 AM.
Re: What compression would you run with a 499 stroker? [Re: challengermike] #1123611
11/29/11 12:49 AM
11/29/11 12:49 AM
Joined: Dec 2010
Posts: 392
Mississippi
lahatte Offline
enthusiast
lahatte  Offline
enthusiast

Joined: Dec 2010
Posts: 392
Mississippi
If you have MS Excel, feel free to try my Compression Calculations spreadsheet, http://www.claylahatte.com

Re: What compression would you run with a 499 stroker? [Re: challengermike] #1123612
11/29/11 01:06 AM
11/29/11 01:06 AM
Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY Offline
Master
MR_P_BODY  Offline
Master

Joined: Jun 2003
Posts: 52,972
Romeo MI
I must be doing something wrong at the wallace one.Its coming up with a 7.21 for the DCR,does that sound correct?i did use the 71 abdc

Heres a pic of all the specs when i built the engine with the 906 heads.




Look at the effective stroke... its 3.04

Re: What compression would you run with a 499 stroker? [Re: MR_P_BODY] #1123613
11/29/11 01:29 AM
11/29/11 01:29 AM
Joined: Aug 2003
Posts: 1,062
Amherst,NY
challengermike Offline OP
super stock
challengermike  Offline OP
super stock

Joined: Aug 2003
Posts: 1,062
Amherst,NY
Quote:

I must be doing something wrong at the wallace one.Its coming up with a 7.21 for the DCR,does that sound correct?i did use the 71 abdc

Heres a pic of all the specs when i built the engine with the 906 heads.




Look at the effective stroke... its 3.04





Why is the effective stroke 3.04? is that because the cam opens to early and closes late? Im sorry, i dont understand all this info.

Re: What compression would you run with a 499 stroker? [Re: challengermike] #1123614
11/29/11 01:38 AM
11/29/11 01:38 AM
Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY Offline
Master
MR_P_BODY  Offline
Master

Joined: Jun 2003
Posts: 52,972
Romeo MI
Quote:

Quote:

I must be doing something wrong at the wallace one.Its coming up with a 7.21 for the DCR,does that sound correct?i did use the 71 abdc

Heres a pic of all the specs when i built the engine with the 906 heads.




Look at the effective stroke... its 3.04





Why is the effective stroke 3.04? is that because the cam opens to early and closes late? Im sorry, i dont understand all this info.




Effective stroke is when you start to make compression
(when the intake closes)

Re: What compression would you run with a 499 stroker? [Re: MR_P_BODY] #1123615
11/29/11 01:56 AM
11/29/11 01:56 AM
Joined: Dec 2010
Posts: 392
Mississippi
lahatte Offline
enthusiast
lahatte  Offline
enthusiast

Joined: Dec 2010
Posts: 392
Mississippi
MR_P_Body, did you happen to get that 3.04 number from my spreadsheet? I see the same number there, but it may be incorrect because the dynamic stroke length calculation needs the correct rod length, and I didn't see that in his information.

Re: What compression would you run with a 499 stroker? [Re: challengermike] #1123616
11/29/11 05:16 AM
11/29/11 05:16 AM
Joined: May 2008
Posts: 5,399
Aurora, Colorado
451Mopar Offline
master
451Mopar  Offline
master

Joined: May 2008
Posts: 5,399
Aurora, Colorado
The stealth heads are about the same cc as your current heads, so unless your changing pistons or milling the heads your going to have about the same compression ratio?
With the cam you mentioned, you may be able to go 11:1 compression, but I would not go to alot of trouble milling the heads if it is just a street car

Re: What compression would you run with a 499 stroker? [Re: 451Mopar] #1123617
11/29/11 08:59 AM
11/29/11 08:59 AM
Joined: Aug 2003
Posts: 1,062
Amherst,NY
challengermike Offline OP
super stock
challengermike  Offline OP
super stock

Joined: Aug 2003
Posts: 1,062
Amherst,NY
the rod is 6.760

Re: What compression would you run with a 499 stroker? [Re: lahatte] #1123618
11/29/11 10:43 AM
11/29/11 10:43 AM
Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY Offline
Master
MR_P_BODY  Offline
Master

Joined: Jun 2003
Posts: 52,972
Romeo MI
Quote:

MR_P_Body, did you happen to get that 3.04 number from my spreadsheet? I see the same number there, but it may be incorrect because the dynamic stroke length calculation needs the correct rod length, and I didn't see that in his information.




No I didnt BUT I see he posted 6.76 for the length...
I used 6.8... that was on the wallace site
EDIT
I changed the rod length... it made very little difference
now its 3.08... it just the 71 degree closing point
that hurt.... if you close the valve sooner it starts
to increase the effective stroke

Last edited by MR_P_BODY; 11/29/11 10:53 AM.
Re: What compression would you run with a 499 stroker? [Re: challengermike] #1123619
11/29/11 09:16 PM
11/29/11 09:16 PM
Joined: Feb 2005
Posts: 4,321
Prospect, PA
BSB67 Offline
master
BSB67  Offline
master

Joined: Feb 2005
Posts: 4,321
Prospect, PA
Quote:

Quote:

Quote:

There are several different DCR calculators that use different closing points


Dont use KB's CR calculator for anything but SCR. I think for DCR (dur at .006) is accurate rather than KB's (dur at .050"). Wallace racing I think has good calculators




I must be doing something wrong at the wallace one.Its coming up with a 7.21 for the DCR,does that sound correct?i did use the 71 abdc

Heres a pic of all the specs when i built the engine with the 906 heads.




If you use the Wallace Calculator, and the actual valve closing point, the resultant DCR will be lower than what is deemed by many as the acceptable DCR for pump gas, i.e. the Wallace calculator gives lower numbers than other DCR calculators. Said differently, if you get a DCR of 8.5 using actual closing point on the Wallace Calculator, you will have serious detonation. This is why I said what I did earlier, there are several claculators that all used different closing points, and wont give you the same results.

What is the cranking cylinder pressure of your current motor, and what is you confidance in the 9.75 CR being accurate? Did you measure or validate the numbers used in the 9.75 CR calc.?

Re: What compression would you run with a 499 stroker? [Re: lahatte] #1123620
11/29/11 09:31 PM
11/29/11 09:31 PM
Joined: Oct 2005
Posts: 4,961
WI
Dcuda69 Offline
master
Dcuda69  Offline
master

Joined: Oct 2005
Posts: 4,961
WI
Quote:

Dcuda69, I'm curious what cam are you using? Do you happen to know the closing angle after TDC (at .006) on the intake valve?




Sorry, don't have the specs. in front of me. It's Comp xr280r solid roller. 242/248@.050 .570/.576 lift IIRC. Idles beautiful at 850rpm with 12" vacuum. Pulls hard and like I said,runs fine on pump swill. My little 245 street tires don't have a chance!

Re: What compression would you run with a 499 stroker? [Re: BSB67] #1123621
11/29/11 10:14 PM
11/29/11 10:14 PM
Joined: Aug 2003
Posts: 1,062
Amherst,NY
challengermike Offline OP
super stock
challengermike  Offline OP
super stock

Joined: Aug 2003
Posts: 1,062
Amherst,NY
Quote:

Quote:

Quote:

Quote:

There are several different DCR calculators that use different closing points


Dont use KB's CR calculator for anything but SCR. I think for DCR (dur at .006) is accurate rather than KB's (dur at .050"). Wallace racing I think has good calculators




I must be doing something wrong at the wallace one.Its coming up with a 7.21 for the DCR,does that sound correct?i did use the 71 abdc

Heres a pic of all the specs when i built the engine with the 906 heads.




If you use the Wallace Calculator, and the actual valve closing point, the resultant DCR will be lower than what is deemed by many as the acceptable DCR for pump gas, i.e. the Wallace calculator gives lower numbers than other DCR calculators. Said differently, if you get a DCR of 8.5 using actual closing point on the Wallace Calculator, you will have serious detonation. This is why I said what I did earlier, there are several claculators that all used different closing points, and wont give you the same results.

What is the cranking cylinder pressure of your current motor, and what is you confidance in the 9.75 CR being accurate? Did you measure or validate the numbers used in the 9.75 CR calc.?





I dont know the cranking pressure,the engine isnt in a car right now.I do trust the 9.75 comp rating,it was done by a performance shop near me when i had them do all my machine work on my engine.I have used a couple calculators on quite a few sites since last night and they all come up about the same 9.75 to 9.77,I think i might just put the same head gaskets on and keep the comp the same for now.Im just worried im going to end up needing to run some race gas or the timing real low.I just sold a 86 buick t type because the price of race gas kept me from going to the track as much as i would like to.It was $80 to $100 everytime i went to the track(including entery fee)

Re: What compression would you run with a 499 stroker? [Re: challengermike] #1123622
11/29/11 10:37 PM
11/29/11 10:37 PM
Joined: Feb 2005
Posts: 4,321
Prospect, PA
BSB67 Offline
master
BSB67  Offline
master

Joined: Feb 2005
Posts: 4,321
Prospect, PA
Quote:

Quote:

Quote:

Quote:

Quote:

There are several different DCR calculators that use different closing points


Dont use KB's CR calculator for anything but SCR. I think for DCR (dur at .006) is accurate rather than KB's (dur at .050"). Wallace racing I think has good calculators




I must be doing something wrong at the wallace one.Its coming up with a 7.21 for the DCR,does that sound correct?i did use the 71 abdc

Heres a pic of all the specs when i built the engine with the 906 heads.




If you use the Wallace Calculator, and the actual valve closing point, the resultant DCR will be lower than what is deemed by many as the acceptable DCR for pump gas, i.e. the Wallace calculator gives lower numbers than other DCR calculators. Said differently, if you get a DCR of 8.5 using actual closing point on the Wallace Calculator, you will have serious detonation. This is why I said what I did earlier, there are several claculators that all used different closing points, and wont give you the same results.

What is the cranking cylinder pressure of your current motor, and what is you confidance in the 9.75 CR being accurate? Did you measure or validate the numbers used in the 9.75 CR calc.?





I have used a couple calculators on quite a few sites since last night and they all come up about the same 9.75 to 9.77,




Yes, I was asking about validating the measurements (head cc, dish ccs, comp. distance), not the calculation. If you had the cranking pressure, you could work the numbers backwards to estimate an acceptable CR for the aluminum heads.

Re: What compression would you run with a 499 stroker? [Re: MR_P_BODY] #1123623
11/29/11 10:57 PM
11/29/11 10:57 PM
Joined: Dec 2010
Posts: 392
Mississippi
lahatte Offline
enthusiast
lahatte  Offline
enthusiast

Joined: Dec 2010
Posts: 392
Mississippi
Ah, well then, I already had 6.76 for the rod length when I did the calculation earlier, so that's why I also got the 3.04 dynamic stroke length.

Re: What compression would you run with a 499 stroker? [Re: lahatte] #1123624
11/29/11 11:06 PM
11/29/11 11:06 PM
Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY Offline
Master
MR_P_BODY  Offline
Master

Joined: Jun 2003
Posts: 52,972
Romeo MI
Quote:

Ah, well then, I already had 6.76 for the rod length when I did the calculation earlier, so that's why I also got the 3.04 dynamic stroke length.




Actually that was what I got also with the 6.76...
the 3.08 was a error

Re: What compression would you run with a 499 stroker? [Re: MR_P_BODY] #1123625
11/30/11 01:26 AM
11/30/11 01:26 AM
Joined: Aug 2003
Posts: 1,062
Amherst,NY
challengermike Offline OP
super stock
challengermike  Offline OP
super stock

Joined: Aug 2003
Posts: 1,062
Amherst,NY
so later down the road i could have a cam custom ground to bring the dcr up some?I was thinking this cam may be alittle small lift wize for this engine any ways.

Re: What compression would you run with a 499 stroker? [Re: challengermike] #1123626
11/30/11 01:41 AM
11/30/11 01:41 AM
Joined: Dec 2010
Posts: 392
Mississippi
lahatte Offline
enthusiast
lahatte  Offline
enthusiast

Joined: Dec 2010
Posts: 392
Mississippi
A Lunati salesman told me the intake valve closing angle of the 60303 is 60 degress. If that's true, it's one of the earliest I've seen. I haven't seen the specs for those cams though.

Re: What compression would you run with a 499 stroker? [Re: challengermike] #1123627
11/30/11 08:10 AM
11/30/11 08:10 AM
Joined: Feb 2005
Posts: 4,321
Prospect, PA
BSB67 Offline
master
BSB67  Offline
master

Joined: Feb 2005
Posts: 4,321
Prospect, PA
Generally, a larger cam with the same ICL will have a lower DCR. Putting in larger cam, and increasing the DCR are kinda going in the opposite directions, but can be done with more aggressive lobes.

Re: What compression would you run with a 499 stroker? [Re: lahatte] #1123628
11/30/11 11:16 PM
11/30/11 11:16 PM
Joined: May 2008
Posts: 5,399
Aurora, Colorado
451Mopar Offline
master
451Mopar  Offline
master

Joined: May 2008
Posts: 5,399
Aurora, Colorado
60 degrees after BDC for the Lunati 60303 cam is correct. The specs are 268/276 advertised duration, 226/234 @ 0,050" duration, 110 LSA, 106 intake centerline, 0.494"/0.513" lift.

Re: What compression would you run with a 499 stroker? [Re: 451Mopar] #1123629
12/01/11 02:03 AM
12/01/11 02:03 AM
Joined: Dec 2010
Posts: 392
Mississippi
lahatte Offline
enthusiast
lahatte  Offline
enthusiast

Joined: Dec 2010
Posts: 392
Mississippi
I just received my 60303 cam kit today. Now I need to get the block machined.

Page 2 of 3 1 2 3






Powered by UBB.threads™ PHP Forum Software 7.7.1