Am I figuring this right?

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From: Bergen County, NJ

Am I figuring this right?

Comp xer 220 224 114 +4
AFR 205s milled .018
Cometic .040
Stock block and pistons

I get SCR of 11.08:1
DCR 8.83:1
Quench .034

So my concern is; should this be OK on 93 Octane or am I going to have trouble in the warmer weather?

Jan 8, 2007 | 08:04 PM

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From: Watertown, NY

I got 11.18 and 8.4

220 intake
224 exhaust
114 LSA
110 ICL
3.9 bore
3.622 stroke
0 piston relief
-.006 piston out of hole
63 cc head chambers (66 CC base - 3 cc mill(.006 per cc/.018 mill)
.040 gaskets

Last edited by brad8266; Jan 8, 2007 at 08:15 PM.

Jan 8, 2007 | 08:21 PM

Thread Starter

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From: Bergen County, NJ

I like your numbers better!

Should run much less chance of knock at 8.4 on 93 Octane - yes?

Jan 8, 2007 | 08:23 PM

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Quote:

Originally Posted by DaddySS

I like your numbers better!

Should run much less chance of knock at 8.4 on 93 Octane - yes?

yeah you will be fine on 93 octane, you could go higher and be ok though. Just be sure to get a good tune because a **** tune can still leave you with knock.

Jan 8, 2007 | 10:50 PM

thehammer69

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Quote:

Originally Posted by DaddySS

I like your numbers better!

Should run much less chance of knock at 8.4 on 93 Octane - yes?

I'd mill .024" or .030" off the head for a respective 62 or 61 cc chamber size. Should put your DCR at around 8.5 or 8.6.

Hammer

Jan 9, 2007 | 03:30 AM

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From: Bergen County, NJ

Thanks gang...how confident are you guys in calculations?

Jan 9, 2007 | 06:08 AM

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Quote:

Originally Posted by DaddySS

Thanks gang...how confident are you guys in calculations?

I used the DCR calculator thats in the Ls1 internal section, everyone says its accurate.

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Jan 9, 2007 | 11:35 AM

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From: Watertown, NY

from the same calculator you have.

0.006 0.050 0.200
Intake Duration - ID (first number) 283 220 155
Exhaust Duration - ED (second number) 291 224 163
Lobe Center Angle - LCA (also known as LSA) 114 114 114
Intake Centerline - ICL (LSA - degrees of advance e.g. 114+2 = 112) 110 110 110

Intake Valve opens - IVO 31.5 0 -32.5 BTDC (- indicates ATDC)
Intake Valve closes - IVC 71.5 40 7.5 ABDC
Exhaust Valve Opens - EVO 83.5 50 19.5 BBDC
Exhaust Valve Closes - EVC 27.5 -6 -36.5 ATDC (- indicates BTDC)
Exhaust Centerline - ECL 118 118 118
Overlap 59 -6 -69 degrees

Bore 3.9
ST = Stroke 3.622
RL = Rod Length 6.098
Number of cylinders 8
Deck Height (how much pistons come out of the hole) -0.006
Piston Dome or Dish (- for a dome + for a dish) 0
Compressed Head gasket thickness 0.04
Cylinder Head Chamber Volume 63

Static Compression Ratio 11.18 :1
Dynamic Compresion Ratio 8.40 :1
Rod to Stroke Ratio 1.68 :1
Bore to Stroke Ratio 1.08 :1

Jan 9, 2007 | 01:07 PM

#10

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Quote:

Originally Posted by brad8266

Your durations at .006 are way off. It looks like you used the "DCR Manual Calculator" tab and only changed the durations at .050. The .006 durations you are using are for a G5X3.

DaddySS, my figures are right. 8.9 DCR is probably going to be a bit too aggressive. Did you already mill the heads?

Jan 9, 2007 | 01:09 PM

#11

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Quote:

Originally Posted by pianoprodigy

Ok lemme go back and check it out, since I am also using this calculator for my setup.

Jan 9, 2007 | 01:11 PM

#12

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Quote:

Originally Posted by brad8266

Where did I go wrong then? If you can help me out here that would be great because i am also using this calculator for my upcoming setup, which is in like a week or so.

See the instructions here: https://ls1tech.com/forums/generation-iii-internal-engine/630637-my-dcr-calculator-if-you-have-comp-grind-doesn-t-get-any-easier-than.html

Don't use the DCR Manual Calculator tab unless you aren't using Comp lobes.

Jan 9, 2007 | 01:19 PM

#13

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Quote:

Originally Posted by pianoprodigy

See the instructions here: https://ls1tech.com/forums/showthread.php?t=630637

Don't use the DCR Manual Calculator tab unless you aren't using Comp lobes.

Thanks man, i got it right now. So how will I know my DCR if I dont know who ground my cam? I have a 231/237 .575 .575 112LSA. Are most cams ground with comp lobes?

Last edited by brad8266; Jan 9, 2007 at 01:25 PM.

Jan 9, 2007 | 06:59 PM

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From: Bergen County, NJ

Quote:

Originally Posted by pianoprodigy

Yes, heads milled, engine complete and running. It runs unbelieveably strong and with just a little bit of KR, interestingly enough only at about 4400 RPM and after closing the throttle and then reapplying at about 30% throttle.

AFR and I put this combo together after a big f13 cam mess. I was going for real strong low end torque and we thought with the 33 to 34 quench and about 11:1 compression it would be fine on 93 octane but this DCR concerns me.

So what are my choices here - bring the engine temp down (I am running a 180 stat), retard the cam, get a different cam, get it tuned and see how it runs in the warmer weather, ????

I have been tuning it myself but I have limited time to keep working the tune on the street.

Ideas?

Jan 9, 2007 | 07:07 PM

#15

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Quote:

Originally Posted by DaddySS

If you are only having a little bit of KR you should check the AFR and probably richen it some which will help with your knock problem. You can also tune your Fuel air multiplier(transient air) table so that it adds a little bit more fuel while accelerating. How is at at WOT? How is your AFR?

Jan 9, 2007 | 07:21 PM

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Quote:

Originally Posted by brad8266

Thanks man, i got it right now. So how will I know my DCR if I dont know who ground my cam? I have a 231/237 .575 .575 112LSA. Are most cams ground with comp lobes?

That doesn't sound like a Comp grind to me. You can just guestimate on the durations at .006 (add 50 degrees to the duration) or you can have it Cam Doctored and get the exact specs.

Jan 9, 2007 | 07:22 PM

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Quote:

Originally Posted by DaddySS

I'm not a tuner, so I'm not sure of the best way to combat a "little" KR. I would post up in the tuning section and be very specific as to when you get the KR (full throttle, part, light, etc) and if it goes away when you pull a bit of timing in that range or add fuel.

Jan 9, 2007 | 07:38 PM

#18

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Quote:

Originally Posted by pianoprodigy

That doesn't sound like a Comp grind to me. You can just guestimate on the durations at .006 (add 50 degrees to the duration) or you can have it Cam Doctored and get the exact specs.

Thanks man, that puts my upcoming setup at 8.82 DCR

Jan 9, 2007 | 07:42 PM

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Quote:

Originally Posted by brad8266

Thanks man, that puts my upcoming setup at 8.82 DCR

Well, see that's where I might be a bit nervous. I'm not really familiar with other grinds. They could be a lot different than +50 and then your DCR could end up being way too high...

Might want to post up and ask if anyone can help you identify your grind.

Jan 9, 2007 | 07:47 PM

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