which motor would make more power

[Guest bastaad525]

hmmm well I think it relates quite well to reality. It's not hard to look at this car or that car and see what any stock factory new car is running and how much hp they are claiming and use that for a basis to compare any car that has run a consistent, given number at the track. The trick is to find some other cars that are around the same weight and run around the same times as your car.

 

Really to me HP is such a theoretical number but it is usually a consistent number as well. But yeah dynos can be wrong and even manufacturers can lie about how much power their cars come with so it's hard to really know for sure. But people love the numbers and want to have that yardstick to measure by.

 

As far as the 300hp discrepancy you mentioned I don't really know but of course I would look supsiciously at the dyno first... what kind of dyno was it? was the operator experienced? How were the runs done? How fast of a sweep did they set it to run (in other words how quickly did they allow it to go up thru the rpm)? How did they arrive at their initial guesstimate of hp? By the way they didn't end up with 'only" ~400hp... they got 518 with some tuning and then over 600 with nitrous, after reading much of that thread I'm not exactly sure how you came up with example in the way that you did. He didn't exactly answer your specific question about the state of tune at the time and such. And I don't get how they were estimating so much hp anyways? What 1/4 mile times were they running and what was the race weight of the car? To me that is a really oddball example overall.

 

Truth is that in MOST cases I have ever looked into, where people had dynoed and had a given rwhp number, and then ran at the track, and also knew their approximate race weight, it seems most of the time it does usually match up very closely, and if it doesn't, it's usually easy to look at the timeslip and figure out why (bad 60' time usually). Sure, there is no doubting that sometimes dyno's will give numbers that are just way out there.... I haven't come acrossed one yet though. At every various stage that I have actually gone and dynoed my car, I have always come away with numbers very close to what I was estimating based on what other people have gotten with their setups. And even going to five different dyno places (not my fault!!! they kept going out of business by the time I returned!) I found that my results were very consistent.

 

Also, if you look at people who go and dyno factory stock cars, they usually do find that their hp to the wheels is very close to the factory claim minus 15% or so. And in the cases where the numbers on the dyno fall short (Mazda RX-8 and late 90's Ford Mustang Cobra come to mind) people have actually gone to the manufacturers and complained with those dyno sheets as their basis, and gotten the manufacturer to revise their HP claim (in the RX-8's case) or to make some changes to the engine/efi/whatever to bring the hp up to their claim (Cobra). So the manufacturers themselves do seem to take the dyno results pretty seriously otherwise they'd just claim "we didn't lie! It's your dynos that suck!".

 

Of course there are other cases like the Dodge SRT-4 which consistently dyno higher than they should given their factory rating... lucky for the guys who buy them but it's not just a fluke... the SRT-4 for instance does run quite a bit quicker at the track than it SHOULD given it's weight and claimed HP, keeping up with much more powerful cars... so in this case the consistently high dyno numbers again do seem to be right on the money.

 

And anyways... if you think about it... running at the track isn't an exact science either. There are just as many variables to driving your car down the 1/4 mile as there are to doing a dyno run. Weather, condition of the ground, elevation, what the driver ate that day Can all make a big difference in how quick you run down the 1/4... so if you run a 12.9 on one pass and a 13.3 on the next, does that mean your car is ~20-40 hp less powerful? Only the guys that go to the track every week and do 100's of runs and get nice consistent times can really even use those numbers for any kind of real basis to claim "oh hey I must be making this much power then!!!".

 

Same thing applies to dyno's I would say... you gotta find one (and an operator) that is proven to be consistent, otherwise who knows if you can trust what it says?