Hey guys,

So quick question. Say for example your Evo X is running around 350WHP how much engine HP would this be?

 

It would all depend and you'd have to hook up the motor directly to the crank shaft to get the engines HP. Because WHP is what's being based off of the wheels. I can tell you that the engine HP is higher then WHP.

 

Yeah I know it's higher. It's just that car manufactures use engine HP when advertising their cars.. for example the stock HP on my MR is 291HP, I'd like to know roughly what that number would be.

 

Depends on dyno also a stock mr on a mustang I thought was like 225 or so

 

http://www.modified.com/tech/modp-10...s/viewall.html

15% is pretty typical on message boards.

If you want something more accurate, look for stock Evo dyno results and compare the results to the advertised HP numbers.

 

Thanks. I would have thought it would be more due to all the diffs etc on the Evo

 

It is. Read the article.

People use 15% because its a very safe number and you wont be overestimating power.

 

The evo x stock dyno's anywhere from 215-235...usually as most ppl have said its about 15-17%. No cars stick hp is what it actually puts down to the wheel. As others have posted, it will also vary on thE type of dyno u use. A mustang dyno is usually referred to as a "heartbreaker" because it gives u a more realistic hp number and that usually kills ppls. The dyno jet will usually give u a higher more bloated number which why ppl like it haha

 

Maybe I can help, or at least contribute good numbers to build a better average.

I dyno'd my GSR 100% stock. I had the original paper filter and stock advan tires even. The weather was, 68F degrees, 5% humidity, 28.93in-Hg barometric pressure (pretty normal)

I put down 264whp/281lb-ft on a Dynojet. Numbers of 225 are really low, but for a 2008 MR I would believe 235ish whp, on a mustang dyno. I suspect I was up around 260 because I have a GSR and because the 11' had a vastly better factory tune and I had one of the newer mufflers that had the valve that opens for better flow. (you can hear it open in the youtube vid I posted)

My tuner put down 251whp on his stock 10' MR, on the same dyno 8 weeks before me when the temperature was around 95F (AZ sucks for heat).

From the OE 291bhp, that's a loss of a ~10%. Therefore either:
1) power-train loss is ~10%
2) The car is "under-rated" from the factory. This case does happen, but not often
3) Dynojet is known for being forgiving compared to a mustang dyno. Lets assume 2% error, 12-13% loss is arguably pretty accurate
4) All dyno readings have an error factor, and really are only useful when comparing to baseline runs (which is why I baselined my car at a local dyno while it was factory, so when I go back this fall with my mods I have a good *real* measurement.)


Here was my chart. Run with 264whp had 1 count of knock, and was running stupidly rich from the OE tune.

 

all depends on type of dyno as others have said.

the generally accepted percentages are around 15% for rwd cars and closer to 18% or maybe a little higher for AWD cars. But that also depends on types of car and awd system.

I usually just take 18% of the crank hp and get my whp.

 

Yes, or even a bit more.

 

Really, the factory number can be taken with a grain of salt as well. All years of Evo X's are rated at 291HP, but 2011's seem to do around 10% or more better stock on dynos due to the different tune.

 

The tune on the 11 is still really rich, but I think the timing tables are different.

The biggest change is the valve that opens in the muffler to allow more flow. On my second dyno pull on the video I posted you can hear it clearly.

 

The guy who posted the dyno jet chart is a perfect example of what a few of us have stated....the dyno jet gives u a really bloated number that a lot of times isn't always realistic, where as a mustang dyno is closer to reality in my opinion.

 

The high-light of this thread so far is the link to a good article that says "the 15% rule is nonsense" followed by the suggestion that you use the 15% rule.

Drive-train loss is pretty close to unique to every car. It varies (albeit by not much) between two different supposedly identical cars, due to slight differences in the gear-mesh and/or fluids. If you really, really care, go weigh your car and then find a shallow down-slope and measure the rate of acceleration for a known angle.