Desk Top Dyno

[JJRJR]

I got some software from Comp Cams that is supposed to be able to calculate your HP/TQ based on various parts, etc. My engine builder says it's pretty accurate if you enter the right data.

I entered the flow data from the Eddy Performer RPM heads, the Comp Cams XE275, Eddy Performer RPM intake, 1.6 Rocker ratio, 10:1 CR, Holley 750, and 3" Headers. According to the software, my 69 383 will make about 515 HP with those improvements and about the same amount of Torque. That's 180 HP gain from the stock 335.

Seems like a hell of a lot, but the engine builder and most others I've spoken to say they aren't surprised. I was shocked to see how much HP is effected by the temperature of the air flowing into the carb. There is about a 20 HP difference between 60 degrees and 80 degrees.

John

 

[george68hemirr]

so this hp/torque is at the flywheel..very cool...drop her in your car and drag the quarter mile to get the true numbers.....you will loose about 115 hp thru the drive train

 

[JJRJR]

No drag strip for me George. Just want a nice looking, strong running RR to enjoy. I always get confused when people talk about "flywheel" HP and "rear wheel" HP. I understand that by the time power reaches the back axle, the power is reduced since the engine has to turn the shaft, etc. I've heard 20% loss. At the end of the day, if everyone is subject to the same laws of physics, then I guess it's a level playing field.

I guess then the 69 RR with a 426 Hemi really only had 340 HP and the stock 383 had 268 HP? Hmmm.

Oh well, I'm sure it will hold its own.

J

 

[moparchris]

Edelbrocks heads flow less than they say by about 10-20% I know since my flow bench isn't as happy as others. Simulated dynos are good to try different cams to find what you need. A 383c.i. motor that makes 500 hp is race motor territory. A pump gas hydraulic cammed flat tappet motor will be in the 400 range. BTW ambient air temp ( the temp of the air in the room) is not the same as inlet temp. Most naturally aspirated motors super heat the carb and the inlet air temp ends up in the mid 100s. I dont want to be a ppopy flavored lollipop but I wouldn't want you to be crushed when it doesn't make big power.

 

[JJRJR]

Edelbrocks heads flow less than they say by about 10-20% I know since my flow bench isn't as happy as others. Simulated dynos are good to try different cams to find what you need. A 383c.i. motor that makes 500 hp is race motor territory. A pump gas hydraulic cammed flat tappet motor will be in the 400 range. BTW ambient air temp ( the temp of the air in the room) is not the same as inlet temp. Most naturally aspirated motors super heat the carb and the inlet air temp ends up in the mid 100s. I dont want to be a ppopy flavored lollipop but I wouldn't want you to be crushed when it doesn't make big power.

I'm sure it won't be as much as the software calculates, but Mopar Muscle Mag did a flow bench test of the BB Mopar RPM heads and came up with exactly the same flow numbers as did Edelbrock's test. With stock heads (906) MM Mag got dyno results of 455 on the 383, at the flywheel of course. They did the Comp XE 285, 850 carb, MP 1 single plane intake and Hooker headers.

J

 

[moparchris]

Edelbrocks heads flow less than they say by about 10-20% I know since my flow bench isn't as happy as others. Simulated dynos are good to try different cams to find what you need. A 383c.i. motor that makes 500 hp is race motor territory. A pump gas hydraulic cammed flat tappet motor will be in the 400 range. BTW ambient air temp ( the temp of the air in the room) is not the same as inlet temp. Most naturally aspirated motors super heat the carb and the inlet air temp ends up in the mid 100s. I dont want to be a ppopy flavored lollipop but I wouldn't want you to be crushed when it doesn't make big power.

I'm sure it won't be as much as the software calculates, but Mopar Muscle Mag did a flow bench test of the BB Mopar RPM heads and came up with exactly the same flow numbers as did Edelbrock's test. With stock heads (906) MM Mag got dyno results of 455 on the 383, at the flywheel of course. They did the Comp XE 285, 850 carb, MP 1 single plane intake and Hooker headers.

J

True, but I have done magazine consulting for Turbo magazine in the 90's and Fastest Street Car Mag now and when a mag does one of those stories you have to understand that Edelbrock is a MAJOR advertiser and true objective testing doesn't happen. Sorry to burst the bubble but dynos have correction factors and the dyno operator can manipulate the numbers to the end result they want. Same with flow benches. For a pump gas, hydraulic cammed, stock headed 383 on a honest dyno will make 400hp at most, since the head is the limiting factor. Most peoples engines dont make the power they think.

 

[69hemibeep]

Edelbrocks heads flow less than they say by about 10-20% I know since my flow bench isn't as happy as others. Simulated dynos are good to try different cams to find what you need. A 383c.i. motor that makes 500 hp is race motor territory. A pump gas hydraulic cammed flat tappet motor will be in the 400 range. BTW ambient air temp ( the temp of the air in the room) is not the same as inlet temp. Most naturally aspirated motors super heat the carb and the inlet air temp ends up in the mid 100s. I dont want to be a ppopy flavored lollipop but I wouldn't want you to be crushed when it doesn't make big power.

I'm sure it won't be as much as the software calculates, but Mopar Muscle Mag did a flow bench test of the BB Mopar RPM heads and came up with exactly the same flow numbers as did Edelbrock's test. With stock heads (906) MM Mag got dyno results of 455 on the 383, at the flywheel of course. They did the Comp XE 285, 850 carb, MP 1 single plane intake and Hooker headers.

J

True, but I have done magazine consulting for Turbo magazine in the 90's and Fastest Street Car Mag now and when a mag does one of those stories you have to understand that Edelbrock is a MAJOR advertiser and true objective testing doesn't happen. Sorry to burst the bubble but dynos have correction factors and the dyno operator can manipulate the numbers to the end result they want. Same with flow benches. For a pump gas, hydraulic cammed, stock headed 383 on a honest dyno will make 400hp at most, since the head is the limiting factor. Most peoples engines dont make the power they think.

You are a poopy flavored lolly pop :jester:

 

[ACME A12]

You are a poopy flavored lolly pop :jester:

Proven on a flow bench no less... :basketcase:

:jester:

 

[Basketcase]

[quote="69hemibeep


You are a poopy flavored lolly pop :jester:[/quote]


any guess how soon that ends up ln an avlatar?

 

[moparchris]

[quote="69hemibeep


You are a poopy flavored lolly pop :jester:

any guess how soon that ends up ln an avlatar?[/quote]
Nah Big is too busy doing updates.

 

[JJRJR]

Thanks for the replies, I do appreciate it. While I understand the business motives for possibly tweaking the numbers a bit in favor of a large client, I find it a little hard to believe that the entire "hot rod" car magazine industry has been publishing lies for decades; not to mention the multi-million dollar high performance players like Edelbrock (many others) that spend millions on R&D and testing. Seems to me that if the pizza shop on the corner is selling garbage, he won't be in business very long. Same for any industry. Companies stay in business and survive because they are trusted and provide quality products and information.

Assuming your skills and flow-bench are as good or better than those of the Mopar Muscle and Edelbrock professionals, and you've found such disappointing results I have to assume that everyone else that spends their hard-earned money on their products would eventually come to there senses and stop buying products that clearly don't perform up to their published standards?


I'm interested to know what facts or specific knowledge you are using to determine that the 383 with stock heads, etc. will not make any more than 400 HP? So, by adding a high flowing aluminum intake, better carb, bigger cam and large tube headers; the best that can be expected from a stock headed 383 is a 65 HP gain? I don't agree. If so, nobody would waste their time or money.

Assuming that the Mopar Muscle Magazine 383 rebuild wasn't all smoke and mirrors as you suggest, they backed up just those improvements with a 455 HP dyno result; a 117 HP gain.


I don't think it's a far stretch to think by adding Eddy Performer Heads, as misleading as you think their flow numbers may be, would add another 30 to 50 HP to that combination. So, whether it's "at the flywheel" or "rear wheels" is of no consequence since the standard is to measure flywheel HP and 99% of people that refer to HP are referring to that stardard; I think.

Don't mean to sound terse, but I put a lot of stock in the opinions of people on this forum and have spent $7,000 on my engine alone based on many recommendations from this forum. To now hear someone chime in and tell me I've spent that money on 65 HP got me a bit stirred up.

John

 

[69hemibeep]

[quote="69hemibeep


You are a poopy flavored lolly pop :jester:

any guess how soon that ends up ln an avlatar?

Nah Big is too busy doing updates.[/quote]
This is like a double dog dare

 

[Basketcase]

l triple dog dare ya!!!!

 

[moparchris]

Thanks for the replies, I do appreciate it. While I understand the business motives for possibly tweaking the numbers a bit in favor of a large client, I find it a little hard to believe that the entire "hot rod" car magazine industry has been publishing lies for decades; not to mention the multi-million dollar high performance players like Edelbrock (many others) that spend millions on R&D and testing. Seems to me that if the pizza shop on the corner is selling garbage, he won't be in business very long. Same for any industry. Companies stay in business and survive because they are trusted and provide quality products and information.

Assuming your skills and flow-bench are as good or better than those of the Mopar Muscle and Edelbrock professionals, and you've found such disappointing results I have to assume that everyone else that spends their hard-earned money on their products would eventually come to there senses and stop buying products that clearly don't perform up to their published standards?


I'm interested to know what facts or specific knowledge you are using to determine that the 383 with stock heads, etc. will not make any more than 400 HP? So, by adding a high flowing aluminum intake, better carb, bigger cam and large tube headers; the best that can be expected from a stock headed 383 is a 65 HP gain? I don't agree. If so, nobody would waste their time or money.

Assuming that the Mopar Muscle Magazine 383 rebuild wasn't all smoke and mirrors as you suggest, they backed up just those improvements with a 455 HP dyno result; a 117 HP gain.


I don't think it's a far stretch to think by adding Eddy Performer Heads, as misleading as you think their flow numbers may be, would add another 30 to 50 HP to that combination. So, whether it's "at the flywheel" or "rear wheels" is of no consequence since the standard is to measure flywheel HP and 99% of people that refer to HP are referring to that stardard; I think.

Don't mean to sound terse, but I put a lot of stock in the opinions of people on this forum and have spent $7,000 on my engine alone based on many recommendations from this forum. To now hear someone chime in and tell me I've spent that money on 65 HP got me a bit stirred up.

John

Well John, I certainly didn't mean to insinuate (spelling) that your engine is going to be a turd. In fact it will be very powerful. My point is that you shouldn't believe what you read. Dyno numbers and flow bench numbers are just that numbers. I cant tell you how many times I have seen a guy go out and buy some big hp engine that makes 700 hp and his 3500 pound car runs 115 in the quarter. As a matter of fact Popular Hot Rodding ran into this problem with their project Chevelle. 700 hp and it ran 113 in the quarter. They spent month after month trying to find the problem only to find their dyno was a little generous. Remember that dynos and flow benches are mathematical equations of force. With that said its easy to manipulate the numbers. As for your 383, well first off 65hp is 20% more power than stock! Thats impressive, you will feel it in the car. For instance, I have a 3450 pound Swinger with a 360 in it. It made 330 horsepower to the wheels. This car with the wrong converter ran mid elevens at 116mph. Most people accused me of lying about my hp (low). I know its hard to believe but most manufacturers do their best to make their product look the best on paper. Its what sells. You can believe what you want and thats cool and these forums are full of desk top racers. I think you will be happy with your engine but you could do more with less. Please dont take offense. We like to be light hearted around here.

 

[george68hemirr]

or the dyno goes the other way and tells you you have less horsepower then you really have......mine was 600hp at the rear wheel on the dyno and the track it turned out to be 735 hp at the rear wheels.....all dynos are different and are just a tuning tool :yesnod:

 

[JJRJR]

Thanks guys, no offense taken. I'm new to this and trying to add just the right ingredients so she'll be a nice pavement pounder but not too crazy. Will just be a weekend car and take to some local shows for fun with the guys. Good, clean fun. I totally understand what you're saying that the dynos aren't exact tools. More likely if I went to 4 different dynos I'd get 4 different results.

Off to Daytona Beach this weekend to pick up front/back seats for the project. She's going into the body shop today/tomorrow and the guy I'm using is going to detail the restoration on his web site. More to come.

As always, thanks for all the advice.

Best,

John

 

[nicanor]

Not a MOPAR but a little history with my 69 Vette. We wanted to buld it just to have 400 hp. We used Speed Pro forged pistons, RHS heads a nice size cam I think it was a 484 lift Lunatia cam, not too big. We tried both a 770 and 670 Holley carb. Currently a 670 Holley, the 770 was too big. Used a 700R4 trans a 3:70 rear. First and second gear is crazy but I have an overdrive rarely needed. Also added a complete MSD system. Never made 400hp. Had to be careful with the cam because I needed (wanted) the vacuum to run the pop up lights, brakes and pop up windshield wiper door.

I bring this up because I brought the Car to the Dyno Shop. They have two different dynos. Once done the first time, it showed 391 at the flywheel. It didn't tune quite right and they said the compression was 12.5 to1. A little high but I still use high test gas, not racing fuel. The car is wicked fast off the line, not much top over 110.

So they put it on their other dyno, not the same type and no changes initially because they were testing for hp increase with the cutouts open and closed. The hp measeured was not near the hp measured on their other dyno and closer to where the numbers were at another place that just did a dyno pull. I don't think the Dyno shop was manufacturing numbers, only that the two different dynos gave different numbers for whatever reason.

Didn't want much more hp in the fiberglass vette because when I first bought it I had to take all the paint off and repaint twice just to get rid of all the cracks.

Your build sounds great and the horsepower whether its 400 or 450 will give you the feel and the sound you're looking for.

Barry

 

[mcmopar]

Trust me, John - you are going to really like the results. Your setup is essentially the same as mine (except all new whereas mine is a little tired) and it is so satisfying to feel that power out on the road. You will be addicted to it the first time you take it out on the open road and put your foot in it.

 

[JJRJR]

Thanks guys!! I can't wait.

I just got word that the car has been towed to the body shop. He's gonna start tearing it down this weekend then off to get media blasted. Still waiting on the heads for the engine build, but that should be done in a week or two. Off to Daytona on Saturday to pick up the seats from a 68 RR. Then once back from blasting, it's time to order the sheet metal.

John