kcruboy

I know several people in here are desperately searching for a way to justify why stock RX-8's are only pulling near 170 hp on a dyno. I understand there are a lot of technicalities that people have tried to use to justify the suspicion that dyno's haven't been telling the whole truth.

However, by looking at stock 8 1/4 mile times, it doesn't appear that the car should have that much more power than the 170 hp everyone is getting. I'm just taking an objective look at the numbers and 170 hp seems quite believeable:

- Most people (on average) are running low 15 sec. 1/4 miles (validated by many members' results from this very site)
- 170 hp to the wheels (approx. 200 hp to the crank)
- 2900 lb car
- 6 speed manual tranny
- rwd

IF average people were consistently pulling low or even mid 14's (YES i know SOME magazines have done it) THEN I could understand why people would be so bothered by the 170 hp number, but the facts seem to make 170 hp very reasonable.

Case in point :
- RSX's dyno about 165-170 hp to the wheels
- Average 1/4 mile times in the real world (www.clubrsx.com) are low 15's
- FWD (disadvantage vs. 8)
- I believe 2,750 lb.s (slight advantage)

Seem quite comparable to me. I'm not trying to start a war b/w rsx's and 8's! This is just as a REFERENCE. Does anyone else see where I'm coming from or have not-too-technical input. I'm not trying to bash 8's, I'm juss simply trying to clarify my own confusion.

RotorMotor04

First of all, I have a hard time believing the Mazda would claim that much more horsepower than the 8 really has. I know they over estimated the 248 at first, but then retracted that. Over stating there horsepower by 48 ponies seems a little much to me.

blksf8

my 8 dynoed at 168. If we estimate a max of 20% loss from crank to wheels, then my car would be making 210 to the crank.

I have taken my data from my dyno runs and sent them to my SF Mazda Regional Manager to investigate. I am going to request for them to buy back the car unless they can do some serious reflashing to get me at least 28 more horsepower to the crank that I am missing. I love the car and it's handling characteristics, but I honestly didn't pay $35k after taxes for a fully loaded RX8 that is missing that much horsepower.

RotorMotor04

210 seems a little more like it. Also, where you have your car dynoed can also play a big role in how much wheel horsepower that you actually make.

Broker73

ok, I think this has been played out enough. In the lastest car and driver I think, I read the article on dyno #'s, and how the car today are getting to complex for that kind of measurement. It has already been posted here, but I can't find the link to provide the article. There was an expert in hte article that stated he dyno'd an M5, and it came in at 80hp under what you would expect. He also stated that these reasults will vary by car, and make, and he had seen some drive train losses of over 30%. I think the 8 is putting down over 230hp, just based on run ins with more powerful cars. Those who think the car only has 210 or so should give their head a shake.
He basically stated that the dyno is no longer an effective tool to read hp, because the computers on cars are way to smart. The M5 example was just one point he highlighted

unorthodox

Excellent article. I think the 8 does take into account a few things on the dyno. My car pulled 179 HP base run to the wheels with your basic dyno fan. But what would happen if we had a more powerful fan that allowed the oil coolers to do their job, and inlet temps to drop accordingly, and the radiator to cool better, and... if the ECU got the readings it was looking for I wonder what would happen to the numbers...

This kind of makes sense because the Torque numbers seem to be spot-on: 132 is what I got and that is 16.9% driveline loss... ahhh! So now as the rev's increase and the speed increases, but airflow does not! The ECU holds things back... and the HP numbers are off!

RotorMotor04

Good point Unothodox. Is there a more powerful fan out there? Same with a radiator?

PhineasFellOff

I'd like to hear what Canzoomer and his people have to say about the article.

blksf8

the article says that Dinan has a $7000 fan that blows 75mph wind.

PhineasFellOff

Mr. Dinan also said in the article that the $7000 fan is not good enough anymore and he is going to invest in a special room that costs something like $250,000, but that this room at that cost can't even approach BMW's special rooms.

tommy12g

after talking with Canzoomer, he says that his numbers on the Base stock car are roughly about 223 to the crank, he also states that Manufacturers are given roughly a 6% leeway with HP claims therefore take the 223 / .94 = 237.23 So Mazda is basically using every available means to say 238 when in reality its about 223 HP. Sorry the numbers don't lie.

Gord96BRG

BWAAAHAHAHAHAHAHA!!! :D

Sorry...

Unless you pulled your engine (and exhaust, cooling, and ECU/wiring) and installed it on an engine dyno and ran the test according to the SAE standard, you haven't got a leg to stand on. Don't even waste the cost of the phone call to request anything of the sort - they'll just mark your file with "Flake". There's dozens of threads here discussing why dyno tests are inaccurate - you simply can't believe the results, especially if you did nothing to disable the 'limp' mode.

Regards,
Gordon

babylou

Could you please tell me where I can buy a 2,900 lb Mazda RX-8? The lightest USA model weighs 3,029 lbs. This might make a bit of a difference in a drag race.

Also, gearing will make a significant difference. I have a vehicle that will do 0-60 mph in 4 seconds but has the same power to weight ratio of an S2000. The difference is my vehicle is geared for low speed acceleration and tops out a bit over 100 mph.

babylou

I say you sue Mazda for ONE BILLION DOLLARS . One proviso; loser pays all legal costs for both sides and court costs.

blksf8

ok, I'll try to keep my opinions to myself for now on. Sorry for trying to contribute to the board.

lourx8

I wonder what Racing Beat found out on their engine dyno. Let me call them...

lourx8

Spoke with Racing Beat. They said that they didn't get a crank HP number. However, the observed HP to the wheels was 176.

Genom

Mazda dealerships would seem like the place to me, since Sport package RX-8's have been weighed at 2960


QUOTE]Originally posted by babylou
Could you please tell me where I can buy a 2,900 lb Mazda RX-8? The lightest USA model weighs 3,029 lbs.[/QUOTE]

r0tor

iTrader: (1)

Where your theory takes a dump is when some people that know how to drive pull off a 14.3 sec and other mid 14 second runs which would not be at all remotely possible for a 200hp 3000 lb car.

Most 15 sec runs are by people who aren't launching the car hard and aren't regulars at the drag strip. My friend run a 14.8sec run with his Trans Am his first couple times at the track, that eventually dropped to a 13.1 sec run with no mods.

lourx8

[/QUOTE]

LMAO!! :D

Lawerence

Nope. If you are making 132tq then your power should be comparable (im not doing the math).

The computer cant just say "im going to pull some HP" because HP is not real, it is a derivitive of TQ. So the TQ qould have to go down also for your theory to be correct.

Also look in the SCC where they dyno the rx8 and it goes into limp mode. It made like 130hp and 80-90tq i think.

Lawerence

No man, I understand how you feel. I think alot of it is just this msg board.

My old car was overrated and I was pretty pissed about that. Eventuallt I got rid of it for the 7. Now I love the power

kcruboy

blksf8....

Sorry to see you get hammered by so many people for your response, but your thinking is along the lines of mine. Your problem is one of the only things holding me back from being able to convince myself to buy an 8 at this point.

Broker73....

Anyone can say I've beaten cars X and Y so my car has Z horsepower, but its all meaningless. Get a dyno done with one of the limp mode fixes or run a 1/4 mile and post your times. Also, to bring you back into the real world, the 8 has VERY little bragging rights on the street right now.

PrOber....

I do see where your argument could make sense. But the point is that the "average" driver is not even pulling 14 second 1/4 mile slips. Sure with a 7k rpm launch, perfect hook up, and perfect conditions, an extremely small number of people have run 14.3 - 14.5. But note that a significant number of these people have been through several transmissions. It's almost like the car can hardly handle the runs.

Maybe estimating that the horsepower to the crank at 200 is a little low, but its hard to justify much more. I could still believe up to around say 215 at most.

Also, just another point to consider... The rsx-s weighs in around 2,750 lb.s and according to the factory has 200 hp to the crank. Although not normally the case, a few drivers have run 14.7 1/4 mile times stock and have posted their time slips to prove it. I readily admit this is not the norm, but neither is mid 14 sec. 1/4 mile times for the 8..... This difference in times can easily be justified by the fact that the 8 is a rwd car (vs the rsx which is a fwd) and is therefore capable of better 1/4 mile times with a similar power to weight ratio.

Sorry for all the rsx-s comparisons, i own one and now know way too much about them.

JimW

The only argument you may have, relates to why Mazda can't provide you with the ability to accurately measure H.P. There has to be a reason and a solution, such as disabiling a sensor or certain equipment. Consumers inherently have a right to test and find out if the products they purchase work, as the manufacturer advertised! If the car dynos within allowable limits after this fact, than fine. If not Mazda should provide the extra power.

Gord96BRG

Sure - so pull the engine etc., and mount it on an engine dyno and test it the same way Mazda does. Using a chassis inertial dyno to compare to Mazda's engine dyno measurements leaves so many opportunities for variation and error that there is NO way it can be used for any valid (or legal) comparison purposes.

Regards,
Gordon