so i went to go dyno my rx8 finally cause they had a $30 special at lone star performance for their car show thing. and i made sure they turned off traction control off and everything and sad to say i was very very disapointed. First run i put 160.3hp, 2nd i put 144hp, and 3rd it was 140hp. It doesn't make any sense cause most people dyno more than that stock! and i got pretty much every bolt on out there. Then my friend that has a stock 70K miles s2000 put 187hp and i beat him by like 2.5.-3 cars everytime we race weather its from a stop or a roll. Do yall think that they dont know how to dyno a rotary or something? cause it took them a while to set everything up for my car. I'll post the dyno sheet later.

 

did they take it all the way to 8500 rpm ? I've noticed a lot of shops stop at 7000 after seeing the dip in hp at that point .....

 

useless without sheet and type of dyno

 

i told them to take it to 9.5K and they hit the rev limiter every single time so i know they took it all the way up there. and it was a dyno jet. I know i'll post the dyno sheet soon. i really dont think they knew what they were doing cause the tach on the computer screen was like going back and forth the whole time and on the dyno sheet it only says they took it to 6.5K btw this was n/a i wasn't spraying

 

Depending on the dyno those are low hp #'s, but in general on most standard dynoes the RX8 does about 180-185 whp, while the S2000's are usually around 205 whp, so the spread is about right.

 

yeah but damn 144 and 140? no way. like i really can't believe that.

 

The tach pick has to be setup property for the RX-8 where it should be once per 360 degrees since it does not use waste spark. Does not matter which plug wire you connect it to. The issue of the tach going all over the place, could be that the pick up is not biting properly on the cable or could be cross touching another cable or also sometimes be attributed on an ignition "missed".

 

The only question that matters:

Did you dyno your car on the same machine that your friend used?

 

This IS an manual transmission, right?

 

^according to the OP's sig - it is...

i don't know too many A/T's with an ACT 6 puck clutch kit and Agency clutch line

 

yeah its a manual and they dyno my car first then my friend's s2k right after. like when they first hooked it up to the spark plug wire it was saying that i was idling at 2.5rpm no matter which wire they used. then some guy came over there and did something and it started reading normal. and it did read fine all the way till it got about 6.5K then thats when it started going all over the place.

 

ever gone to a drap strip? you can estimate your horsepower by your trap speed and the weight of your car.

 

It would help a lot to see a plot. What does the torque curve look like? Where does it make peak tq and peak hp? Does it show the the appropriate bump from opening the secondary ports? It should be pretty obvious from the plot if their RPM pick up ran up to 9k or not. What was your peak torque? HP is determined mathematically from torque and RPM. If they f'ed up the rpms, you could very well have f'ed up HP numbers. For a car running basically bolt-ons, it should not drop 12.5% between runs. As soon as they put up a 144 run after a 160 run, it seems likely they screwed something up. *IF* your car is only 160 hp, which is not impossible on mediocre/poor compression, then it should dyno 160, 159, 157 - consistent. Losing a couple ponies from the car heating up is likely. Losing 10+% is not. And, if they screwed up the second and third run, they probably screwed up the first as well.

 

so in a nutshell what you are saying is "they f**ked it up " !

 

same dyno? the s2k typically dynos higher than the 8. on dynojets they will pull off over 200 whp while the 8 pulls about 170-180 whp. this sounds normal to me depending on the dyno used. mustang?

maybe your friend can't drive and that's why you beat him from stops and rolls.

 

1) what kind of dyno? mustang? dynojet?
2) how many miles on your car?
3) weather conditions?
4) how long since you cheked / replaced your coils, spark plugs, and maybe even the ignition coils? Is your air filter clean?

 

what gear were the dyno pulls done in?

 

Well, my point mostly is the amount of missing data greatly exceeds the amount of data provided. The OP posted a question about a poor dyno result but all we know is the peak HP of the 3 runs and a loose comparison to another vehicle on the same dyno. You can tell a lot about a car from a dyno plot but very little from the peak numbers. My car dynos and puts up good numbers but when I look at it I can see where the car needs fixing/investigation. If the RPM pickup was bad, the entire plot should be screwed up. However, if it's a mustang dyno and something broke between the first and second runs (maybe the secondary port valving), then the dyno could be correct. Some Rx8s will dyno 175 stock. The OP has some pulleys and a midpipe so maybe you would expect 185 (if it was 175 stock). I wouldn't be surprised if the intake, header, and catback resulted in little if any HP. Then again, maybe that combination works really well. So, the plot would tell us a lot more than just the peak HP numbers.

 

I had the same problem with my car until I de-carboned my engine. No joke, I was at around 145 - 150hp then once I de-carboned my engine I gained 30hp back on the same dyno machine.

Was your hood open so fresh air could get in? Was your engine hot when they first strapped your car down and made the runs? How soon after each run did they do the next dyno run?

 

What is the equation to find hp from trap speed and wieght of the car?

 

De-carboned? YOu mean revving your engine all the way to redline once a day to clear the carbon build up? Or do you use some sort of chemicals into the engine? Cuz I would love to gain 30 hp really quickly.

 

There is a DIY decarb proceedure in the DIY forum. You can order the Mazda official engine cleaner or use seafoam or similar solution. It's an easy process. It will not produce any result in an engine that is not afflicted with carbon build up. If carbon build up is very bad, it may not be enough to fix the problem. If carbon buildup is not the problem, it likely won't help much at all.

 

^^what he said. Its a special chemical. Well I dynoed my car and I was barely breaking 145hp and I was really concerned, so I de-carboned my engine then a week later I got my car dynoed again and if I remember correctly, I redynoed at 175-178hp without my Mazsport Ignition Solution. And the weather was basically the same..hot, but the big difference was that I had my hood open and waited a few minutes before each dyno run.

 

Why is this in the "Major Horsepower" Section?

Anyways, what gear did they do the pull in?

What was your torque?

When was the last time you check/changed your coils and spark plugs?