Detailed LT1 specs?
11-20-2002, 10:14 PM
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Detailed LT1 specs?
I have a stock '94 and I've got this program, Desktop Dyno 2000, and it wants all this info about the LT1 that I don't know. What is the induction flow CFM @ what inHg (What's inHg anyway?! :confused:) and also, what is the stock camshaft profile on my LT1? Intake and exhaust lift @Valve, Lifter, IVO (BTDC), EVO (BBDC), IVC (ABDC), EVC (ATDC)? Can anyone help me out?
11-20-2002, 10:46 PM
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Re: Detailed LT1 specs? (GDP)
What's inHg anyway?!
11-21-2002, 03:25 AM
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Re: Detailed LT1 specs? (GDP)
I have used DD2000 for LT1 simulations. Induction flow isn't that critical as long as its not too small. Use 780 cfm for throttle body.
Head CFM flow is done at a specific value of inches of HG (HG is mercury). The number will depend upon what the flow bench was set at when the test was made. It should be provided with the flow test data. Most are at 28 in with some done at 25in. You can find stock LT1 head flow data along with lots of other heads on AFRs website in an article by Chevy High Performance.
Your going to have a tough time with the stock LT1 cam. I don't think anyone has noted the intake centerline of the stock cam so exact valve open and close values are not known. Most aftermarket cam mfrs give the open and close events for their cam. Be sure you use the valve timing measured at .050. You'll never get good results with seat to seat. Lift is also given by the cam mfrs. Use the number for the rocker ratio you run. Some cam mfrs give lift for 1.5 and 1.6 ratios. Desk top dyno does not do the simulate cams that are run with ratios higher than 1.5.
Head CFM flow is done at a specific value of inches of HG (HG is mercury). The number will depend upon what the flow bench was set at when the test was made. It should be provided with the flow test data. Most are at 28 in with some done at 25in. You can find stock LT1 head flow data along with lots of other heads on AFRs website in an article by Chevy High Performance.
Your going to have a tough time with the stock LT1 cam. I don't think anyone has noted the intake centerline of the stock cam so exact valve open and close values are not known. Most aftermarket cam mfrs give the open and close events for their cam. Be sure you use the valve timing measured at .050. You'll never get good results with seat to seat. Lift is also given by the cam mfrs. Use the number for the rocker ratio you run. Some cam mfrs give lift for 1.5 and 1.6 ratios. Desk top dyno does not do the simulate cams that are run with ratios higher than 1.5.
11-21-2002, 04:44 AM
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Re: Detailed LT1 specs? (AquaMetallic94LT1)
It's inches of H2O, not inches of Mercury ;).
For what its worth, DDyno isnt very good. It has no input for windage, or ring tension, etc. It may give you semi close numbers.... then again it may be way off.
I think the free demo of Engine Analyzer from performance trends is far more accurate. http://www.performancetrends.com would be worth a look.. the demo may still be un-neutered.
Of course, if you like you can mail me and I'll send you some stock flow numbers... don't remember offhand what they were across the board :)
-Phil
For what its worth, DDyno isnt very good. It has no input for windage, or ring tension, etc. It may give you semi close numbers.... then again it may be way off.
I think the free demo of Engine Analyzer from performance trends is far more accurate. http://www.performancetrends.com would be worth a look.. the demo may still be un-neutered.
Of course, if you like you can mail me and I'll send you some stock flow numbers... don't remember offhand what they were across the board :)
-Phil
11-21-2002, 08:37 AM
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Re: Detailed LT1 specs? (SkarodoM)
It's inches of H2O, not inches of Mercury ;).
Hg is the chemical symbol for mercury
11-21-2002, 11:16 AM
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Re: Detailed LT1 specs? (vader86)
I should have been more clear:). The cylinder head flow numbers are in inches of water, 28" depression being standard. The throttlebody/carb numbers are in Hg, 1.5" being what I believe most use.
-Phil
-Phil
11-21-2002, 11:20 AM
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Re: Detailed LT1 specs? (vader86)
It's inches of H2O, not inches of Mercury ;).
then why did they use Hg?
Hg is the chemical symbol for mercury
then why did they use Hg?
Hg is the chemical symbol for mercury
11-21-2002, 11:24 AM
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Re: Detailed LT1 specs? (SkarodoM)
I should have been more clear:). The cylinder head flow numbers are in inches of water, 28" depression being standard. The throttlebody/carb numbers are in Hg, 1.5" being what I believe most use.
-Phil
-Phil
