Real HP

**jdenn47** · 01-15-05, 02:16 PM

I have a 86 Vette with cast iron heads and the rated HP is only 235.
Is that a true HP fiqure as a lot of V6's today have more than 235 HP?
I have heard that they rated HP differently due to all the Pollution Crap they had on it back then and it would be more equivalent to near 300 HP by todays standards. Any feedback ?

**SSTibet** · 01-15-05, 02:47 PM

Originally Posted by jdenn47

I have a 86 Vette with cast iron heads and the rated HP is only 235.
Is that a true HP fiqure as a lot of V6's today have more than 235 HP?

I am by no means an expert on this. But I have followed threads here and in other forums saying that the Hp figures are measured / stated per SAE standards and it is the power at engine output with all accessories attached (hence all of the emission stuff, air conditioning, heater, etc.). I have also read that GM states its power ratings somewhat lower than designed power due to some customer liability issues.

I have also read that Hp is stated at the rear wheels, but I do not think that is true.

Cheers,

Selim

P.S. You may refer to Ken, side admin, who is a true expert on these matters.

**redc4corvette** · 01-15-05, 04:12 PM

ON the L98 motor well it's just a truck motor and is a torker for pulling big loads.
I think it's over rated at 235 hp..

**vetteboy86** · 01-15-05, 05:34 PM

Actually if you have an 86 with cast iron heads the hp rating is 230 hp, big deal right. I think they are a little underated. I was sitting at around 260 rwhp per a G tech meter, and stock motor. Either way you look at it, you are sitting at 6 second car to 60, which isn't bad for a 20 year old car. If you want you can purchase a cheap Gtech meter. They are a good toy to play around with.

Craig

**Edmond** · 01-15-05, 08:05 PM

The rating that is given is the power at the flywheel. The situation you're talking about where they started rating them different was back in the 70's where they measured hp without any accessories or pollution items on it.

In the case that people talk about RWHP, it's usually after someone has measured it, be it on a dyno or a G-tech like Craig has done. I think some people will call it real world horsepower because it's what hits the ground.

Yes, there are many V6's that are out there today. If you're concerned about them outrunning you, don't. Comparing a Corvette to a V6 isn't a fair comparison, especially when you factor in the age difference. What L98's are known for are for it's massive torque that peaks around 3200 rpm.

And there's nothing wrong with bolting on a few exhaust mods like a set of long tube headers and a nice free flowing catback system. That could get you 30 horsepower. If you still have the stock exhaust on there, it's very restrictive and only flows out of one outlet on each muffler.

**warren s** · 01-15-05, 08:34 PM

Dont forget that its touque that makes a car accelarate, horsepower has more to do with how fast it will eventually go. Many V6s can make lots of horsepower these days but it doesnt mean the car is very fast. Gearing and light weight combine to make some small cars with not that much advertised horsepower pretty quick.

The SAE NET horsepower is the standard for compairson. Only recently has the access to dynos been so great that people can compare rear wheel ponies.

Some engines were rated (gross) on the dyno not even installed in the car, and some were rated below their power peak for various reasons.

The switch to SAE NET in the early 70s produced lower numbers because the engines were installed in the car as you would buy it. Horsepower was measured at the flywheel.

04c5ragtop · 01-15-05, 08:44 PM

I remember a line I read somewhere - "Horsepower moves cars on the showroom floor, torque moves them on the track".

Tim

**Edmond** · 01-15-05, 08:53 PM

You also have the advantage of rear wheel drive. It'll take more work to pull something than to push it.

**vader86** · 01-16-05, 02:34 PM

YES, the 86 is accurately rated in NET HP terms at the FLYWHEEL, as are all cars since the mid 70s.

It puts down about 200 at the rear wheels, and using 15-18% drivetrain loss, you'll come out with about 230-235. (depending on heads and transmission)

The 86 will smoke nearly all mustangs and any V6 i've come up against, remember you also have 330 lb-ft of torque that will get you moving alot faster than your opponents.
However, the torque number, on my car at least, is not correct. The car puts down a little over 300lb-ft, and I found, after my dyno testing, that the car puts out about 350lb-ft at the flywheel. This number will vary from car to car a little though.

**Vettefan87** · 01-16-05, 07:26 PM

So my Gtech meter was about 65 HP wrong when I got about 265 at the Rear wheels with only doing a chip, airfoil, and mufflers, since I know those mods are probably good for ten or so that makes it 50 off? Can somebody explain?