My 87 305 Iroc is rated factory at 190.....is that really what they dyno....or did GM underrate the engine?

Has anyone dynoed their stock 305? I'd like to know....alot of people have told me that GM underrates their engines for insurance reasons.....

 

Dude, have you hit the gas? That told me that mine wasn't under rated! Maybe even over estimated! No really, I would like to see some stock 305 dynos as well, but who dynos a stock engine?

BamaZ28

 

As a rough calulation of a stock 305 with 190 HP & 295 TQ and a 20% drivetrain loss the numbers would be about 150RWHP & 236
RWTQ. Give or take a few, but nothing to brag about.

 

I was under the assumption that 190 was the horsepower at the rear wheels and 295 was the torque at the RW....150HP seems kinda low.....

 

Stock 305 auto for 1987 only.
190 HP @ flywheel
295 TQ @ flywheel

Well thats why everyone (almost) wants a 350. Thats all its got without extensive Mods (note money) and you will not get much more, my opinion.
AND DON'T ASSUME ANYTHING!!

 

It would be useful for us to actually understand how hp is measured.

There are basically 3 way of measuring it.

- gross hp

- net hp

- rear wheel hp

Gross hp is the hp developed on an engine dyno, with no accessories causing parasitic hp loss, i.e., water pump, AC, alternator, etc.

Net hp is what current manufacturers have used since the 1970s. This is engine dyno power with all accesories running. That will cause about 30 to 40 hp to be deducted from the gross.

Rear wheel hp is net hp minus 15% loss for manual transmissioned cars, and 20% for automatics.

So, say we have a 305 making 230 hp gross. Let's see what we come up with.

230 - 30 hp = 200 hp

200 - 20% (40hp) = 160 hp at the rear wheels.

Now, let's use my 305 as an example. To the best of my knowledge it will produce about 305 hp at its highest gross level.

So let's deduct 30 hp for parasitics and we come up with 275 hp. If this engine were sold by GM, this is the hp rating they would give it.

Consider that GM assigns the L98 350 engine only 235 hp and you can see that the little 305 has a lotta cajones when built right. And I am only using mild, commonly available parts.

Now we subtract 20% to account for my 700r4 automatic.

275 - 55 = 220 rear wheel hp.

That will take an average 3600 lb. Camaro through the quarter mile in the mid- to low-14 second category.

What's wrong with that?

 

5.0= 305 HP to the best of his knowledge. So to the best of my
knowledge

 

Go to the Dyno and see what your car does..NOT ALL CARS ARE THE SAME.......One might not be in tune the other might be etc. etc. etc.

Even then they say aome dynos are more unforgiving then others...Soooooo I suggest you hit the dyno and be happy with it.

 

Is that a measure of your intelligence?

Since when did one hp per cubic inch become BS on a small block Chevy? It is a simple as following the parts I used in building your own.

Really, save your childish antics for your sandbox.

 

Not all car are the same. My car is rated @ 230 HP and 300 TQ. It dynod at 209 HP and 270 TQ. So around 200HP without Borla. The gears I dont think would make a difference on the dyno nor the K&N.

 

Was this dynoed with the engine in the car? Out? Accessories accounted for or not?

For a stock L98 that sounds about right. 235 hp x 15% = about 200 hp at the rear wheels.

No mystery that I can see.

 

This might help.. CLICK HERE

 

So my factory speced 190HP Iroc really only puts 150HP to the rear wheels? Thats depressing....

 

yea the engine was in the car. Everything was in the car..AC/heater...etc. stock 305 not L98. if you click on my sig theres my car on the dyno.

 

I took a look at your car--VERY nice

With 210 hp at the rear wheels you should be doing the quarter in mid 14s.