DEsktop Dyno port flow data on BB
Thread Starter
Instructor
Joined: Oct 2001
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From: Austin TX
DEsktop Dyno port flow data on BB
Just got DD2000 installed and started to run a few simulations. I was disappointed in the cylinder head data that is available in the pull down. Where do I get additional head flow data (other that taking heads to the shop with a flow bench)? I am looking for flow info for stock BB rectangular port, closed chamber heads for starters. I would then like to see the impact of pocked porting. Any advice? :eek: :eek:
Race Director
Joined: Nov 2000
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From: Waterloo ontario Canada
Re: DEsktop Dyno port flow data on BB (l78vetteman)
Fully reworked the maximum you can get out of those heads is 326 cfm at .700 and around 310 at .600. The exhaust quit flowing at .500 with around 210 cfm.
Using the formula .257 x cfm x 8 cylinders these ported heads could support 635 horsepower at .600 lift before the intake took it's toll. Intakes can cut flow down by as much as 20%.
Sorry I don't have stock flow for these heads.
Using the formula .257 x cfm x 8 cylinders these ported heads could support 635 horsepower at .600 lift before the intake took it's toll. Intakes can cut flow down by as much as 20%.
Sorry I don't have stock flow for these heads.
Drifting
Joined: Jul 2002
Posts: 1,820
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From: Puyallup WA
Re: DEsktop Dyno port flow data on BB (l78vetteman)
Doing computer based simulations are a mixed bag at best. To give you an idea, I have the DD2000 and I plugged in my EXACT numbers for everything prior to running the engine on the dyno. The guesstimate was over 50hp and 30ft/lbs low compared to actual engine dyno numbers. Computer simulations can be fun but there is no replacement for actual dyno time. How many times have you run across someone that says their motor makes 500hp only to find out that it is based on a computer simulation? They instantly lose credibility.
As far as head flow data, the only real way to get data that has any meaning would be to actually have the heads flowed, before and after modifications. I know a lot of people are afraid of the cost associated with this but sometimes you can find an individual that is willing to do it reasonably. It has been a while since I have had any stock heads flowed but I have seen people, including me, ruin the flow by incorrectly porting them.
I don't consider myself a head porter, but I know a few that are phenomenal. The best way to modify a set of heads is with access to a flow bench and/or consulting an experienced head porter. There are actually many little things that can make big improvements.
As far as head flow data, the only real way to get data that has any meaning would be to actually have the heads flowed, before and after modifications. I know a lot of people are afraid of the cost associated with this but sometimes you can find an individual that is willing to do it reasonably. It has been a while since I have had any stock heads flowed but I have seen people, including me, ruin the flow by incorrectly porting them.
I don't consider myself a head porter, but I know a few that are phenomenal. The best way to modify a set of heads is with access to a flow bench and/or consulting an experienced head porter. There are actually many little things that can make big improvements.
Race Director
Joined: May 2000
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Re: DEsktop Dyno port flow data on BB (542C2)
The value of simulation programs is the comparison of one configuration to another. There are too many variables, and in the case of DD2000 the input is too crude to predict absolute numbers with great accuracy.
Pocket porting/port matching will typically yield 5 to 10 percent more top end power, and is usually worth the work, especially if the engine is down for an overhaul and you do it yourself
DD2000 is very good for comparing cams - assuming you can characterize them satisfactorily, which isn't always the case. Once you have established a configuration, you can start testing cams, and select the one that meets your torque bandwidth specification. The absolute numbers may not be accurate, but the the cam that makes the best torque bandwidth in the simulation will likely do the same on the real engine, and it's a lot cheaper to run cams on the computer than rent a dyno cell for several days to test them.
Once you have selected a cam you can add horsepower with head, inlet, and exhaust system work and the only limitation is usually one's budget.
Duke
Pocket porting/port matching will typically yield 5 to 10 percent more top end power, and is usually worth the work, especially if the engine is down for an overhaul and you do it yourself
DD2000 is very good for comparing cams - assuming you can characterize them satisfactorily, which isn't always the case. Once you have established a configuration, you can start testing cams, and select the one that meets your torque bandwidth specification. The absolute numbers may not be accurate, but the the cam that makes the best torque bandwidth in the simulation will likely do the same on the real engine, and it's a lot cheaper to run cams on the computer than rent a dyno cell for several days to test them.
Once you have selected a cam you can add horsepower with head, inlet, and exhaust system work and the only limitation is usually one's budget.
Duke
Safety Car
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From: Pettis Performance 565 with two stages of Nitrous Supply nitrous 1.082, 4.61 at 155, 7.17 at 192
Re: DEsktop Dyno port flow data on BB (SWCDuke)
For a complete list of cylinder head flow data, stock and aftermarket check http://www.chevyhiperformance.com :chevy
Thread Starter
Instructor
Joined: Oct 2001
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From: Austin TX
Re: DEsktop Dyno port flow data on BB (SWCDuke)
Duke,
I totally agree with you perspective. The ralative changes from some baseline are more valuable than the absolute HP or torque predicted with simulation SW. :D :D
I totally agree with you perspective. The ralative changes from some baseline are more valuable than the absolute HP or torque predicted with simulation SW. :D :D
