I am going to a larger cam in my 383 and I have looking for some adivce from guys with real world cam experience.

I have done a some desk top dyno runs and have found that I can get just about the same peak hp with both of these cams. The shorter duration cam has more torque on the bottom end.

Larger cam - 234/242 112 LSA 107 intake centerline
Smaller cam - 226/238 112 LSA 110 intake centerline

The results are theory so I don't know if the real world results will be the same. Any thoughts ?

 

Depends how you want to go In the imortal wors of John Lingenfelter "always build for torque" the ower end torque will give you more Drivability on the street. If its the same HP Id say torque!!!also That LSA on the first cam is steep do you want power brakes?


[Modified by ASRoff, 12:26 AM 1/18/2002]

 

What are the lift numbers? Who makes these cams? But in general I would also build for TQ.

 

Without getting technical here, I don't see those cams helping out much from a dead stop but if you are at freeway speed and have the valvetrain to support more RPM's it might help. What is it you are looking for from the engine??

 

Im building a setup as well. Is there software available that will allow me to plug in some variables and get a hp rating?

 

Red there are several most use desk top dyno about 40 bucks or one like I have is called engine analyzer I can't remember the price but i think it was around 90 dollars much more sophisticated program.

 

For what it's worth, I have heard that DD dyno has trouble simulating cams with different exhaust/intake durations. I have never been able to make DD reproduce the LT1 torque/HP curve. It always shows too much low end power.

Eric

 

Put these numbers in:
Int Cl 115º
Int: 230º @.050", .350" lobe lift, Open@ 2º BTDC, Closes @48º ABDC
Exh: 236º @.050", .350" Lobe Lift, Open@ 55º BBDC, Closes@1º ATDC

When you want it made, call Schneider @ (619) 297-0227 :)

 

These are the results I get from DD2000:

LT4 Hot Cam
439HP @ 5000, 505 ft lbs @ 4000, low end 457 fl lbs @ 2000


Off the shelf Crane cam:
Larger cam - 234/242 112 LSA - thats the LSA
107 intake centerline .539/558 lift
485hp @ 5500, 509 ft lb @ 4500, low end 423 ft lb @ 2000

My custom ground cam design:
Smaller cam - 226/238 112 LSA
110 intake centerline .539/.558 lift
483hp @ 5500, 507 ft lb @ 4500, low end 436 ft lb @ 2000

BBA Scnieder cam:
471HP @ 5500, 504 ftlbs @ 4500, low end 430 ft lbs @ 2000

Just for Grins:
230/248 112 LSA, 114 IC gives 513 HP @ 6000 and 501 ft lbs @ 4500

Eric - when you compare the stock LT1 motor with the factor power curve, make sure you use the tunnel ram intake, small headers and dual exhuast. The placement of the intake center line is crucial for correct results. Finally, remember that GM is rating the engine using the SAE which calls out a specific atmospheric pressure, temperature, and humidity levels. It is also supposed to be rated with all accessories operating. I think desktop dyno will give you SAE gross results. I was going to try doing my own simulation but AFRs website (where I get the flow data from for LT1 heads) has been changed and the article links don't work now.


[Modified by AquaMetallic94LT1, 4:08 PM 1/18/2002]


[Modified by AquaMetallic94LT1, 4:14 PM 1/18/2002]

 

Sounds like a great science project you got going there. What does your car currently on the strip with the Hot Cam?

 

AquaMetallic... One thing I don't know if your considering, when I designed the cam, I tried to keep as very little overlap as possible when the piston is at TDC while maintaining horsepower. The theory being overlap is what kills idle and low speed driveability.

I was toying with designs over 500 HP, but finally decided I could not get the idle quality I wanted, so I backed off total duration for better idle vacuum ( I think it also helps computer calibration issues. )




[Modified by BBA, 10:44 PM 1/18/2002]

 

Do you have flow numbers for your AFR heads? I would probably go with the smaller of the larger of the two grinds you originally listed, though if you are looking to maximize idle, I would put it on a 114lsa/110I.C. and bump up the compression 0.2 points or so.

In fact, looking at your compression I would go 11.2:1-11.5:1 depending on the cam size, lsa, etc. This will improve your performance across the board (idle to peak hp), and actually help fuel economy also. The first cam you listed would have no problem with the compression level.


But quite a bit of this is going to depends on the flow characteristics of the heads and your exhaust.

What kind of idle quality are you looking for. With the larger cam on a 114+4 and a bump in compression in a 383/388 it should have similar idle characteristics to a hot cam in a stock bottom end.