Im running 105mph in the quarter @ 12.73. I have a 355cid, dart 2.02/1.6 64cc cast heads, headers, 9:9:1 forged trw, accelerator intake, 780 holley hp(built to engine specs). Car weighs about 3500lbs. Pump gas, and Flowmasters. What would someone think the approx. HP rating is. I cant really afford a dyno. I was told around 400hp. I also have a 400sbc I want to build, small budget about $2500-$3000 without carb. I figure with that I could get 450hp+ out of it. Engine is good, only has about 25k mi. on a mild rebuild not run hard at all. I do want different heads, it has cast double hump on it now. 2.02/1.6 64cc maybe go with dart eagle heads the 215s or 230s. Thanks

Yes , yes, and yes. You have it all right. Get the 215 heads though.

Im running 105mph in the quarter @ 12.73. I have a 355cid, dart 2.02/1.6 64cc cast heads, headers, 9:9:1 forged trw, accelerator intake, 780 holley hp(built to engine specs). Car weighs about 3500lbs. Pump gas, and Flowmasters. What would someone think the approx. HP rating is. I cant really afford a dyno. I was told around 400hp. I also have a 400sbc I want to build, small budget about $2500-$3000 without carb. I figure with that I could get 450hp+ out of it. Engine is good, only has about 25k mi. on a mild rebuild not run hard at all. I do want different heads, it has cast double hump on it now. 2.02/1.6 64cc maybe go with dart eagle heads the 215s or 230s. Thanks
=
Probably closer to 350 FWHP at a guess.
You also have to remember that this if the HP you have on the run in question under the conditions that prevail, not corrected dyno numbers unless you happen to be running at seal level with really good air....

MPH is a pretty fair indicator of HP but you have to make a reasonably decent run for it to be somewhat close.
In other words You cannot smoke the tires to half track & expect the MPH to mean much :D

Here is a little formula that has been around since at least the 70's & was used by Chrysler Corp. in their drag racing program & written up in the American Journal of Physics in 1973
HP=(.00426*MPH)³ * WGT

I used to add about 50 HP to the number because trap speed is measured differently now than it was in the 70's but Harold Sutton posted this multiplier a while back.
Quote from Harold
"I got the multiplier from the Meaux Racing Heads site and think it's pretty good. It is (1.0072 x the new MPH = the old MPH), "
which is probably a lot more accurate given where it came from.
So,,,, new formula would be---- HP=(.00426*MPH * 1.0072)³ * WGT

EX:,,,,,,,.00426*105 * 1.0072=.4505³ =..0914*3500=320HP


I find this formula works pretty fair until you get into some of the very hi end cars like Pro Stock. I find with cars like these it will give you a higher HP number than you usually see.

THIS IS FWHP, NOT RWHP

Sad but true.

I've seen a fair amount of chassis dyno results from my own and other cars. Just for reference.

3500 lb muscle car 330 RWHP = 109-112 MPH trap
3300 lb stock eliminator prepped car 400 RHWP = 123-126 MPH trap

I'd guess you are making about 280-285 RWHP which works out around what Mike said on the engine dyno.

I've NEVER NOT seen someone disappointed with their chassis dyno results.


Funny how 450 HP in a magazine article used to be a STOUT engine, now they all make that.

Heck, I did a dyno test myself once for a magazine article and was missing a tad bit of HP so I moved the IAT sensor closer to the exhaust and found that missing power.

Funny how 450 HP in a magazine article used to be a STOUT engine, now they all make that.

Remember when the big tire guys would run 12's and the magazines would drool over them???

It brightens my day every time I think my little 400hp SBC is more powerful than the old 396/375hp engines. (advertised of course)

Now Doug...you weren't supposed to give THAT secret away!! What would the California boys do??

JIM

This is what I got...

316 @ the rear wheels and 373 @ the flywheel.

http://www.windyhollowdragway.com/horsepower2.htm

Almost 400hp at the flywheel. Of course this does not factor in aerodynamics, weather and gearing. It is a good approximation to start with and compare how much a weight reduction or hp increase will affect your times.

I also had to add in driver weight - just guess at 170#

Here is the link if you want to put in your exact weight and change numbers around.

http://www.virtualengine2000.com/FreeCalculator.htm

http://www.hotrodink.com/Images/data/546/1hauntedz281.jpg

Thanks guys, I was just curious. So around, 350hp, and about 270 on the rear wheels. So I could gain about 100hp with that 400sbc on a $2500-$3000 budget?

Almost 400hp at the flywheel. Of course this does not factor in aerodynamics, weather and gearing. It is a good approximation to start with and compare how much a weight reduction or hp increase will affect your times.

I also had to add in driver weight - just guess at 170#

Here is the link if you want to put in your exact weight and change numbers around.

http://www.virtualengine2000.com/FreeCalculator.htm

http://www.hotrodink.com/Images/data/546/1hauntedz281.jpg
--
Most of these online calculators are WRONG
The above formula I posted is for engine HP & has been around for a long time & has been proven reasonably accurate for stock body type cars up to about 140 or so
Problem is a lot of these sites are copying each other & are using this basic FWHP formula & calling it RWHP

If you want to see how far off that Virtual thing is input something everyone is familiar with,, Pro Stock
Try 205 MPH & 2350 lbs
Now do you really think any of the Pro teams are making over 1900 FWHP?? :rolleyes:

Want to see a pretty good discussion regarding an outstanding program with a few real world examples??
http://speedtalk.com/forum/viewtopic.php?t=3068&postdays=0&postorder=asc&start=0

Thanks guys, I was just curious. So around, 350hp, and about 270 on the rear wheels. So I could gain about 100hp with that 400sbc on a $2500-$3000 budget?
=
It can probably be done depending on what you have to start with but in honesty, I would say no, not with decent parts.
You are going to have $1000+ in a decent set of heads,, another $500 in forged pistons, that is half your budget & you still need a "few" other parts plus a "little" machine work ;)

Of course,,,, there is always nitrous :D

Mike,

I skimmed that article and it was talking of a 460-480hp BBC running 11.20s @ 3800lbs? Im sure my suspension package isnt close to what would be on this car. But if I build my 400sbc at around 450hp (as I have researched what the dyno would be) Shouldn't mine be in the low 12's high 11's at best. I run at heartland park in Kansas, @ sea level . On a good air day, it will run 1260's in the 105-106mph range. Keeping the Crank and Rods from the 400sbc, and spending around $2500-3k on the rest of it 450hp should be achieved?

The 400sbc has only about 25k on it and wasnt drove hard. I had it in a Firebird and was a daily driver. I will keep the crank and rods. I seen a dart iron eagle head kit for it 1450.00 with intake. I calculated the cam, lifters, pushrods, KB piston set, gaskets and bolts. Came to about 2500 with shipping. I will use my hp carb, distributor and timing chain. Machine work will be done free by one of my sponsors. Does that sound about right to get me the 450hp or close to that I am looking for?

I agree, they will never be exact. The Pro Stock Engine is way out of the envelope for typical online calculators. Those engines cost as much as a house, have hand built sheet metal intakes, almost 15:1 compression and spin to 10,000 rpm

A basic calculation is better than none at all though.

--
Most of these online calculators are WRONG
The above formula I posted is for engine HP & has been around for a long time & has been proven reasonably accurate for stock body type cars up to about 140 or so
Problem is a lot of these sites are copying each other & are using this basic FWHP formula & calling it RWHP

If you want to see how far off that Virtual thing is input something everyone is familiar with,, Pro Stock
Try 205 MPH & 2350 lbs
Now do you really think any of the Pro teams are making over 1900 FWHP?? :rolleyes:

Want to see a pretty good discussion regarding an outstanding program with a few real world examples??
http://speedtalk.com/forum/viewtopic.php?t=3068&postdays=0&postorder=asc&start=0

I agree, they will never be exact. The Pro Stock Engine is way out of the envelope for typical online calculators. Those engines cost as much as a house, have hand built sheet metal intakes, almost 15:1 compression and spin to 10,000 rpm

A basic calculation is better than none at all though.
=
Sorry but with this I don't agree,,
A basic calculation that is wrong is in my opinion worse than none at all :sad:

I am aware the Pro engine is out there, it was just a simple example of how far off that thing is
We are talking over 500 HP off, not just a few HP here,,, this has nothing to do with how much the engine costs or the RPM it spins.
It takes a certain amount of power to accelerate a certain amount of weight a certain MPH for a certain distance.
There are obviously a lot more factors than just HP but this is still the basics.

And I already stated the formula I gave you in my first post has been proven to be reasonably accurate with stock body type cars to about 140mph or so.

I will agree that none are going to be exact but if you go read the link I supplied you will get some idea of just how accurate a good calculator can be.
If you want a calculator that is pretty damn accurate download Larry's
ET Analyst for drag racers.
Now this is a real program :thumbsup:

There are others but this one is excellent for the money,,, CAN YOU SAY FREE :eek:
http://www.maxracesoftware.com/products.htm (http://www.maxracesoftware.com/products.htm)

The 400sbc has only about 25k on it and wasnt drove hard. I had it in a Firebird and was a daily driver. I will keep the crank and rods. I seen a dart iron eagle head kit for it 1450.00 with intake. I calculated the cam, lifters, pushrods, KB piston set, gaskets and bolts. Came to about 2500 with shipping. I will use my hp carb, distributor and timing chain. Machine work will be done free by one of my sponsors. Does that sound about right to get me the 450hp or close to that I am looking for?
=
Well, with free machine work & the parts listed yes, 450HP is probably doable for your stated budget.
I personally would not build the engine with these parts but yes, it should make the power you are looking for or close to it.
For one I would use a better rotating assembly with forged pistons & always prefer an internally balanced assembly if possible which is not going to happen with stock rods,,,
And I don't do machine work for free,,, :D

Have fun with your project,, :beers:

Wolfy
So let me get this straight...
You saying that the American Journal of Physics knows more about
physics then the "late model" internet clowns? but they can change their own oil and plug, so they gotta know their stuff - right?
Next youre gonna tell me there are cars with engines makin around 400hp and runnin in the 10s, and just over 500hp and running 9s, this just cant be, can it? I remember talkin with David Vizard and he told me he built a 347 SBF, that made about 500hp and it went deep in the 9s at 2300lbs.

Im running 105mph in the quarter @ 12.73. I have a 355cid, dart 2.02/1.6 64cc cast heads, headers, 9:9:1 forged trw, accelerator intake, 780 holley hp(built to engine specs). Car weighs about 3500lbs. Pump gas, and Flowmasters. What would someone think the approx. HP rating is. I cant really afford a dyno. I was told around 400hp. I also have a 400sbc I want to build, small budget about $2500-$3000 without carb. I figure with that I could get 450hp+ out of it. Engine is good, only has about 25k mi. on a mild rebuild not run hard at all. I do want different heads, it has cast double hump on it now. 2.02/1.6 64cc maybe go with dart eagle heads the 215s or 230s. Thanks What does the car weigh with you on board and ready to run? That is the number you have to have to guess the appx. horsepower closely.

So in a 406SBC, 10.2:1 comp,5.7 rods,Vic Jr. Holley 750dp,200cc heads (2.05/1.6) 3000 10" stall,th350,& 3.73's @ 3450 lbs. what hydraulic cam to see 11.0-1.5's ?

I agree, they will never be exact. The Pro Stock Engine is way out of the envelope for typical online calculators. Those engines cost as much as a house, have hand built sheet metal intakes, almost 15:1 compression and spin to 10,000 rpm

A basic calculation is better than none at all though. Try more like 17-1 or 18-1 compression and they have been turning them about 10,200 from what i hear with new super light valves and 1200+ lb. vavle springs. They also cost as much as a real nice house and a racer from here blew up three of them at the first race of the season. Even after you know what kind of horsepower a motor makes it still doesnt tell you how fast it will accelerate.

Im running 105mph in the quarter @ 12.73. I have a 355cid, dart 2.02/1.6 64cc cast heads, headers, 9:9:1 forged trw, accelerator intake, 780 holley hp(built to engine specs). Car weighs about 3500lbs. Pump gas, and Flowmasters. What would someone think the approx. HP rating is.

I ran a 12.87@104.75, with a 357, Dart 200cc heads, 10.6:1, etc... very similar engine. My car probably weighs a bit more though, I'd guess 3800 or so.
FWIW I dynoed at 345hp/346tq SAE corrected on a local chassis dyno. I'm figuring about 415 hp at the motor.

Well...


So in a 406SBC, 10.2:1 comp,5.7 rods,Vic Jr. Holley 750dp,200cc heads (2.05/1.6) 3000 10" stall,th350,& 3.73's @ 3450 lbs. what hydraulic cam to see 11.0-1.5's ?

Hey Wolfy...

Don't ruin my day!!

Just tried my pump gas 540 in that on line calculator....Man....I'm making 960 HP!! WOW..that wasn't too hard!!

I feel better already!!


JIM

Wolfy
So let me get this straight...
You saying that the American Journal of Physics knows more about
physics then the "late model" internet clowns? but they can change their own oil and plug, so they gotta know their stuff - right?
Next youre gonna tell me there are cars with engines makin around 400hp and runnin in the 10s, and just over 500hp and running 9s, this just cant be, can it? I remember talkin with David Vizard and he told me he built a 347 SBF, that made about 500hp and it went deep in the 9s at 2300lbs.
=
Hey Rafel,,
I would never say that,, everything I learned came from the internet,,, no,,, wait,,, there was no internet back then,, :clonk:

Hell, I think I even had to get off my a$$ to change the channel on the tube,, phones had wires hooked to them,, :D ,,, life was tough,,

Hey Wolfy...

Don't ruin my day!!

Just tried my pump gas 540 in that on line calculator....Man....I'm making 960 HP!! WOW..that wasn't too hard!!

I feel better already!!


JIM
=
Well,,, actually they are correct for Corvettes in the SW,,, different air :D :D

You mean all I have to do is load it in the back of the pickup and head west? Man..that's a LOT easier than getting my hands dirty...

The hardest thing about gaining a 100-150 Hp in that scenario is stopping for a Super Big Gulp along the way!!

PS-Hey you know what? I just figured out I live in the center of the Universe and there must be a huge vacuum here..because if I head East or West....they always make more power!!

PSS-The funny part is when they all show up at the track,,,,they are all racing on the same "dyno" and the rest doesn't matter!


JIM