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Old 10-18-2008, 12:06 PM
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Horsepower Claims

Do todays engines really make all the horsepower you see people claim or is it wishfull thinking? Do programs like desktop dyno overstate what you would get in the real world? I remember when 1HP per cubic inch was pretty good, now I see people claiming a whole lot more then that. As an example here is an actual Ad for an engine that is for sale, see what you think, would it make the HP he claims?

"Ford 347 stroker shortblock
It is built on a 1988 Ford Mustang High Output (HO) roller block. It has been hot-tanked, cleaned, bored 0.020 over, line-honed and new freeze plugs, cam bearings and crank bearings. The hardware is Keith Black hypereutectic dished pistons (+6cc), forged rods, nodular crank and main GIRDLE. I was planning on installing Edelbrock Victor Jr. cylinder 60cc heads, resulting in a compression ratio of approximately 9.5:1 so this will work fine on pump gas! This motor is good for around 600 horsepower at 6500 rpm redline IF you finish off with the right parts and NOS, about 450 without. One word, if you want to run NOS, keep it low. Due to the hypereutectic pistons, don't go over a 125 shot of squeeze or you'll melt them. It is accompanied with a windage tray, fluid-damper and flywheel. The entire assembly has been balanced to 50 ounces. The build sheet is included Top it off with a strong camshaft, proper heads and intake setup and you'll easily get a naturally aspirated 450 horsepower a little more if you use NOS up to ONLY 150 shot due to the hypereutectic pistons. The build sheet is included."

Morgan

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Old 10-18-2008, 12:17 PM
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i've always wondered that to its wierd because like a new truck thats rated at 300-345 hp feels slower than my 305 GMC which would surprise me if it has 220HP yeah it just don't add up.
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Old 10-18-2008, 02:41 PM
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A lot is internet or desktop dyno b.s. 1 hp per inch is still pretty`good in a steetable engine.Most oem #s are acurate tho measured at the flywheel not the rear wheels.
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Old 10-18-2008, 03:13 PM
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I don't see a cam listed anywhere there, I think you would be pushing 400 Hp naturally aspirated with a good parts selection and still have it streetable.

The big kicker there is the cam and heads, you can't ever make a hp claim without those important pieces of information. I wouldn't exceed 400Hp from 350 ci without forged pistons, but thats because I want it to last and I've been there and done that. Hypereutectics are for tight clearances and low blowby on a street engine.

If you want big block power in a street engine you want a big block, not some high strung 7500 rpm small block that needs $5000 in parts to make it live.

You can't change the laws of physics, there is no replacement for displacement.

Of course now I will be bombarded with guys saying their motor made over 400HP from their stroked 350 SBC etc.

But a stroked 302? c'mon.
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Old 10-18-2008, 03:21 PM
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Quote:
Originally Posted by Morgan22
Do todays engines really make all the horsepower you see people claim or is it wishfull thinking? Do programs like desktop dyno overstate what you would get in the real world? I remember when 1HP per cubic inch was pretty good, now I see people claiming a whole lot more then that. As an example here is an actual Ad for an engine that is for sale, see what you think, would it make the HP he claims?

"Ford 347 stroker shortblock
It is built on a 1988 Ford Mustang High Output (HO) roller block. It has been hot-tanked, cleaned, bored 0.020 over, line-honed and new freeze plugs, cam bearings and crank bearings. The hardware is Keith Black hypereutectic dished pistons (+6cc), forged rods, nodular crank and main GIRDLE. I was planning on installing Edelbrock Victor Jr. cylinder 60cc heads, resulting in a compression ratio of approximately 9.5:1 so this will work fine on pump gas! This motor is good for around 600 horsepower at 6500 rpm redline IF you finish off with the right parts and NOS, about 450 without. One word, if you want to run NOS, keep it low. Due to the hypereutectic pistons, don't go over a 125 shot of squeeze or you'll melt them. It is accompanied with a windage tray, fluid-damper and flywheel. The entire assembly has been balanced to 50 ounces. The build sheet is included Top it off with a strong camshaft, proper heads and intake setup and you'll easily get a naturally aspirated 450 horsepower a little more if you use NOS up to ONLY 150 shot due to the hypereutectic pistons. The build sheet is included."

Morgan
I would stay away from this one. He contradict's himself in the same add.

[This motor is good for around 600 horsepower at 6500 rpm redline IF you finish off with the right parts and NOS, about 450 without. One word, if you want to run NOS, keep it low. Due to the hypereutectic pistons, don't go over a 125 shot of squeeze or you'll melt them.]

[The build sheet is included Top it off with a strong camshaft, proper heads and intake setup and you'll easily get a naturally aspirated 450 horsepower a little more if you use NOS up to ONLY 150 shot due to the hypereutectic pistons.]

I agree with you on the facts of 'computer program' horse power ratings being high, and 'engine dyno' ratings being high. The true test of HP is 'in chassis' dyno's.
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Old 10-18-2008, 05:19 PM
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This is the typical HP "creep" that seems to be never-ending. You combine a novice and a couple of car mags and all of a sudden he's making mega HP.

I'm happy with "a little warmed over" with (now days) mileage.
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Old 10-18-2008, 05:24 PM
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Do engines make the claimed power ?

Who knows, it depends who is making the claim.

If it is the Ford Motor Company or General Motors, then yes they do.
If it is "Fast Freddy from the pool room" probably not.

Does a foot really contain twelve inches, or have inches shrunk over the years?
That is what you are really suggesting.

Power is extremely easy to measure on a dynamometer. And a dyno is extremely easy to calibrate very accurately by anyone wishing to check it with very simple equipment. All you need is to be able to accurately measure rpm electronically, and some accurate pound reference weights.

I have a Hewlett Packard digital frequency counter, and some barbell exercise weights that have been checked and very accurately measured for weight. That is how I calibrate the dyno in my own garage. Dead easy.
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Old 10-18-2008, 05:38 PM
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Quote:
Originally Posted by Silver Shadow
Do engines make the claimed power ?

Who knows, it depends who is making the claim.

If it is the Ford Motor Company or General Motors, then yes they do.
If it is "Fast Freddy from the pool room" probably not.

Does a foot really contain twelve inches, or have inches shrunk over the years?
That is what you are really suggesting.

Power is extremely easy to measure on a dynamometer. And a dyno is extremely easy to calibrate very accurately by anyone wishing to check it with very simple equipment. All you need is to be able to accurately measure rpm electronically, and some accurate pound reference weights.

I have a Hewlett Packard digital frequency counter, and some barbell exercise weights that have been checked and very accurately measured for weight. That is how I calibrate the dyno in my own garage. Dead easy.
My question to you, is how can you simulate vehicle weight, and gear ratios?
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Old 10-18-2008, 05:52 PM
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Quote:
Originally Posted by carsavvycook
My question to you, is how can you simulate vehicle weight, and gear ratios?
Why would you want to do that ????

A dyno measures rpm and torque, and calculates horsepower. That is all it does.

Vehicle weight and gear ratios have absolutely nothing to do with measuring horsepower.
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Old 10-18-2008, 07:05 PM
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re: Horse power Claims

Hey Silver shadow, why the attitude?

Quote: "Does a foot really contain twelve inches, or have inches shrunk over the years?
That is what you are really suggesting"

Since you think so much of my question, here's one for you.

Is it faster to carry your lunch or walk to work?

Better yet, What can move at the speed of light but yet can't exceed it?

Hint, it can be observed and has no mass.

lighten up.......it's all good..........
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Old 10-18-2008, 07:14 PM
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Quote:
Originally Posted by Silver Shadow
Why would you want to do that ????

A dyno measures rpm and torque, and calculates horsepower. That is all it does.

Vehicle weight and gear ratios have absolutely nothing to do with measuring horsepower.
If that was the case, How come it shows "Power HP" on this Dyno test?

By the way, they thought they had a 'Cash Cow' (NOT)with this vehicle and they would not run it over 3000 RPM on their vehicle Dyno. They claimed 'supposedly smoke' from the tail pipes, and 'pinging' at higher RPMs. The 'supposedly smoke' was tire smoke, and not from the tail pipes.

They were also informed about a 'possible' fuel quality problem, and asked to drain the tank, and re-fuel it with higher octane fuel. They did not do this, and they quoted to pull the heads to check 'quench'.

The 'original' in chassis Dyno(from another local Dyno shop) showed 450HP, and 420 foot pounds of torque @ 6500 RPM. This was 4 years ago.

The 'second Dyno' was to see where it was at after fine tuning, from the last 4 years.

My attachments would not load. Sorry.

Last edited by carsavvycook; 10-18-2008 at 07:26 PM. Reason: Forgot to hit the UPLOAD button. It is not UPLOADING!
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Old 10-18-2008, 07:28 PM
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what is with you guys ??

A horsepower is a very simple and basic engineering unit of measurement.
It is very clearly defined as:
Hp = rpm x torque (in Ft/Lb) divided by 5252

The unit has not changed in almost three hundred years since James Watt defined it.

There is nothing in that formula that requires vehicle weight, gearing, or acceleration. The original unit was measured by the good Mr Watt using a genuine hairy horse.

Do engines make their measured horsepower.
Yes of course, if the measurement was made correctly.
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Old 10-18-2008, 08:19 PM
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Take a 'horse' with a 125lb rider, and a 'horse' with a 300lb rider. Which 'horse' will win the race?

Chill out.
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Old 10-18-2008, 08:20 PM
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Honestly,,I don't know,,what I do know,is that I was part owner in a Nascar series Late Model Monte,the engine was built by a very reputable builder in Centralia Wash,the other partners and I watched him build that engine over a period of about 4 months.The goal was 575 to 600 HP,once he got to around 400,then the work began.He has his own dyno room and he would install parts,dyno,change parts,dyno,and after some very expensive parts had been installed and a lot of testing,he finally reached about 625 HP.What I'm trying to say is that it didn't just happen with the turn of wrench under the shade tree,he had to work at it.So I think a lot of claims of high HP is probably a lot of dreaming.I have a pretty healthy small block,but it has been built on a very tight budget,it doesn't have titanium valves and a 38LB stainless crank and all of the other goodies that could produce that type of horsepower,so unless he can show the receipts for that kind of HP,,,don't buy it.
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Old 10-18-2008, 09:12 PM
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Yes you are quite right. Up to a certain point engine development is pretty easy, then it starts getting really difficult when all the really big improvements have already been made.

The trick is to be able to make precise and repeatable dyno measurements, and reliably detect small changes. There are however a few short cuts. The air flow bench, and software engine simulation are great, but in the end the dyno does not lie.

There are some pretty smart people out there, and beating them, or even being competitive against them is a pretty big challenge.

How much money you have comes into it. I have never raced, I cannot afford to. But as a wealth challenged hot rodder, do a bit of my own engine development here for myself at home. Having my own dyno at home opened up a whole new world for me. A home built airflow bench can be built for almost nothing, and is another great tool to have if you are really serious.
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