modification? Is it all hype?

I'm thinking about all the performance modifications I plan to make. Performance Products Cold air upgrade 11.8 hp gain $250 Power flow intake kit 12 hp gain $600.00 Unichip plug and play 18.8 hp gain $790.00 Headers and muffler 22 hp gain $2500.00 Is this real horsepower gain or hype? Whats your experience with these type of modifications?

Take the claims with a grain of salt, but mods do indeed work. Maybe cut those HP claims in half and you'll be pretty close to reality (for the most part). Whatever you choose to do mod-wise to your engine, you should get it professionally tuned afterward for the best running engine, and to take most advantage of your specific mods.

Actually less than 20 hp gain. Except for supercharging, big time performance increases just aren't there. Step up to a TT if big hp is important to you.

what they said. you can't really add them all together to get a HP number when combining mods.

Someone recently posted that a 996 motor achieves 90% volumetric efficiency right out of the box. It stands to reason that the last 10% is tough to get at - of course a turbo changes that!

As already said those claims are not additive and are already perhaps overstated (way). Having said that modding is still a kick. Nobody is actually going to measure your hp after mods are installed so who cares. Have fun and claim anything you want. Your car will still kick most "common" cars on the road and look good doing it.

i do. i am on first name basis with my dyno operator for what we spend on these mods, i test them.

a supercharger doesn't hurt either

wanna test out a Lightweight flywheel b4 i put one in my car i know it helps..but just to stroke my ego..i wanna know how much

So do us all a favor and post all of your dyno sheets for every mod you have done (before and after). Then post the report delineating the measurement uncertainty of the dyno itself (including precision (R&R), linearity, bias and stability)...as if this actually exists. Oops...some of my experience dealing with measurement systems coming out...sorry!

sure. i'll do it if you send me a clutch and flywheel at your cost. my mechanic is standing by. just say the word. i've been dying to do this mod.

okay. here's my first mod. it was a biggie supercharger. did the dyno runs at XAT racing. before and after on the same chart. i have no idea what the answers are to the smartass tech questions you asked, but it's a good before and after gauge and it's certainly better than the "butt" dyno numbers that get thrown around on here here's my second mod. suncoast headers. did the dyno runs at Zfever. they also use a dyno jet, but with a much larger drum. this is much more accurate for high hp cars. i would tend to agree as my base line run is much closer to what it should have been in the beginning. a friend of mine tune's big HP MB's and turned me on to them. he switched from XAT to Zfever based on their heavier drum dynojet. now, i did not give the ecu any time to adjust after the install of the headers. did a base run, drove down the street, installed the headers, drove back down the street and did the after run. good results none the less, but probalby would have been better had i got some mileage on the car for the after run and give the ecu time to readjust. there is a dip in the HP below 4K, but it actually goes about 27HP higher than stock at 5K with better peak numbers. they make a nice product. i'm curious to know if that low RPM dip might have been cured by allowing the ECU to adjust. i have an overlay chart, but it doesn't use the best "after" run. Stock Headers Suncoast Motorsports Headers next on the list is high flow cats, or even cat bypasses. haven't decided which direction, but dynos will follow. frankly i don't see how you guys can spend a $1000 on a product, but won't spend $50 to see if it actually works.

Fantastic, thanks for the posts...now...let's please be civil...My questions about the measurement systems (i.e., dynos) are not "smartass". I have spent a fair amount of time evaluating measurement systems and the variation inherent in them is unbelievable (~86% are not capable). As a very simple example, have you ever taken your blood pressure? Measure it back to back to back and see what you get. The variation you see is due to 1. the natural variation of the human being and 2. the measurement process. Do you know how much of each? So if you ran the same car on the same dyno with the "same" conditions (e.g., environment) would the results vary? This is part of the measurment uncertainty, short-term (also called error). If this is not included when the dyno sheets are published...well let's just say the data is suspect! I would love to study some dynos to get a handle on the error. Sorry for my rambling and no offense intended.

There is only one way to measure improvements in power and that is to put it to the pavement. So many people love to claim these high hp figures yet have no idea what it translates to on the road. or, even more suspect, they DO know how it tranfers and they found that their performance just doesn't match their claimed hp number. I think these people are referred to as "dyno racers". Kind of like putting a big sweat sock down the front of you pants.....all show, no go.

I would just like to see some G-Tech times or something like that. Maybe 2nd gear pulls from 20-60mph, to remove the launch from the equation. I think you can still use dynos to see a relative gain or loss to your baseline measurement, though - as long as the ambient temp is pretty close between the two runs. You just can't say that you definetly have X hp based on a dyno run, because they all test differently.

Omar I can tell you first hand, that the LFW does work. I dont thing it gives HP persay, but it does reduce the rotating mass..but I know you know that. I can tell you that it is a bit of seat time to get used to it. Its on or off, its a bit harder to push down, it does make some noise. It does rev faster and it feels like it gives the car HP. I dont think you will see the gains on a dyno, but sure as hell will feel it in your seat.

Yeah - a flywheel that weighs 15 or more pounds less than the original is gonna effectively make your car accelerate like it lost maybe a 100lbs or so. Same goes for wheel weight.

i was just teasing about the "smart *** tech questions" you and i haven't corresponded enough to know how sarcastic i generally am Man, you a techy though, aren't you. I am starting to get a headache just from trying to decipher your post as far as the info being "suspect", not really. if you look at the runs corrected, it takes most of the "variables" (temp, atmos pressure, etc) out of there. not to mention i'm not the only one who has come up with almost the same exact gains for both mods.

well, i think it's pretty clear my car has both show and go but since you mentioned it. i did do some informal testing with a friend on the way back from sebring last weekend. he has a 95 993. an exceptionally fast one. he only has cat bypasses and a chip, but his car hauls ***! we have raced (roll, drag) many many times. our cars were about dead even, with the slight nod to my car if we let it go long enough. anyway, we did two roll ons from about 50 on the highway. it wasn't even close. i walked on him badly both times. so there's some real world testing my friend. aside from going to an officially sanctioned NHRA 1/4 miles event, this is about as good as i'm going to get for now. although i would like to make some runs with the speedtracer software in the near future when i can find a good location. i'd still like to see those 1/4 mile slips from your run 1999. that sounds very impressive. i still like doing dyno runs, regardless if they have value or not. if someone claims 10hp from a muffler, then at least i better get my 10hp for $1000. seems only fair if you ask me.

i like lwt flywheel, aux oil cooler, baffled oil pan and suspension mods. personally i dont give a hoot about hp. if if have better suspension, i will have more fun and drive faster than an identical car with equal driver regardless of how much hp the other car has. 20hp horsepower gain? why bother with the potential problem you might have? CEL, air/fuel mixture problems, longivity etc etc. now if you are talking about a 200hp gain, then it's a different story all together.

I'm a statistician...or nerd...duh! I still would love to analyze a dyno for uncertainty...I'll never change! No worries...peace out!