Im posting this thread so everyone will get accustomed to the DPHI (dollars per hp increase) of their various aftermarket performance parts. This is really easy to do if you have dyno sheets of the parts you are going to by, and/or you cant make a decision on two very similar parts.

DPHI is the estimated dollar amount you will pay per single hp gain. It is calculated by taking the proposed (or exact) hp gain, and dividing that number by the total cost of the item. For example:

Intake A costs $250 with dyno-tested increase of 8hp.
Intake B costs $300 with a proposed gain of %10 in hp. (or a 16hp gain)

For Intake A: 250/8=31.25 so with Intake A you will be paying appx $31 per hp
For Intake B: 300/16=18.75 so with Inatke B (if 16hp gain is true) you would pay appx $19 per hp

This tool is very useful in finding out exactly how much you will pay for every little increase, which is awesome for comparing similar parts.

Heres a list of the DPHI for some other items. All hp gains are claimed by manufacturer, prices were taken from online sources

Scion Speed Turbo:
Stage 1: hp+ 104 27 DPHI ($2849)
Stage 2: hp+ 136 26 DPHI ($3549)
Stage 3: hp+ 200 27 DPHI ($5499)

ZPI Turbo:
Stage 0: hp+104 29 DPHI ($2999)
Stage 1: hp+160 25 DPHI ($3999)
Stage 2: hp+200 28 DPHI ($5699)

TRD Supercharger:
hp+40 75 DPHI ($2950)

So as you can see DPHI is very useful for helping to decide whether or not to buy certain products. I hope this post helps out a few ppl.

 

Peak numbers != best gauge of power

 

It is a good start though. But to add some accuracy you could create an index for each mod using its average power gain over the powerband . Then calculate your DPHI using that number. It would take seeing the entire dyno sheet though and using the data points (the more points used the better).

 

In no way are these numbers here meant to be a guide for buyers. They are just examples in pulling data from online sources. Ideally one should have a dyno-readout-comparison when buying the more expensive performance upgrades.

Simply put: DPHI should be used as a comparison before anyone buys performance parts. Especially when those parts are very similar. Get the most bang for your buck!

Another reason I put this up was to show the insane cost of the TRD supercharger: At nearly $3000 the claimed horsepower increase is a measly 25%.

 

BUt you don't have to worry about the Highway Patrol towing your car for having an illegal turbo installed when you buy the TRD. Think of the extra money as "peace of mind". And the whole warranty issue, naturally.

 

lol... yea, cus we know that the chp pulls LOT of ppl over for that.

 

does any of that include the cost to have it installed or tunned? thats gonna make all the DPHI go up (especially the TRD because they are gonna make a killing alone off the installs).

 

Ya I wouldnt worry about the police pulling you over for an illegal turbo? i have never heard of that, must be something new that cops have training to know that you have an illegal turbo in your car

 

The $3000 price tag on the TRD Supercharger is for the part only.
I imagine it would cost around $900+ to have it installed and probably more to have it tuned at a dealer.
But the good thing is, its virtually bolt-on, just like the turbos listed above. So having someone install it would be foolish. But thats just my opinion, cause i have experience working on cars.

 

i THINK the trd sc will be around $3400 dealer installed, no tuning needed on a stock tc. i think 3400 is worth it... and one word comes to mind....warranty

and as dr isotope said, cops CAN tow your car if they know there is an illegal turbo on it.. and you say...

"breakaway, how do they know i have an illegal turbo on my car?"

and i answer, if a cop hears a BOV, he CAN request to look under the hood. and if he/she knows their stuff, they can tow it. i know cases of this happening. the only places a cop cant look without a warrant is the trunk, hatch (unless they can see in it), glove box (unless it is unlocked), center consol (unless it is unlocked), and any other areas that are consealed and locked.

 

^^ There are about a million exceptions to where they can look and when they can look, so NEVER feel comfortable about where you think they can or cant look in your vehicle. It would surprise most people how easy it is for them to prove probable cause.

But, as far as every state I have lived in, you have nothing to worry about with the turbo. I guess you california drivers should worry with your strict emmissions laws, but a good majority of us could care less about that part.

 

way off topic there guys LOL. i think thats an illegal post you have under your hood.

 

Yeah, I don't think there is such a thing as an "illegal turbo" unless you're trying to meet CARB in CA..

That's kind of ridiculous. I can build a car from scratch, it can make ridiculous power, but as long as it has the state/federally required saftey equipment, and meets local sound ordinance among other small things like ground clearance and ride height. There is nothing that states you can't have a turbo on your engine.

 

yea, whacha talken' 'bout? I agree with tekniq, unless there its some weird state laws you have

 

Rule of thumb: Cops can and will search your car anywhere if they want.

 

anywhere you let them. you do have rights.

 

Ya the cops cant go into all parts of your car with out a warrant, dont you listen to jay z , 99 problems, the glove compartment is locked so is the trunk in the back, and i know my rights you go need a warrant for that,

 

Well... you think you do.. and you should.. but dont count on much support from the courts. About 10 years ago the cops thought they had sufficient right to destroy my car searching it and arrest me in the process (long, long story). After talking to an attorney, they had ZERO right to even do so much as pat me down, much less search my car. The state courts even agreed. The supreme court of course sided with the cops over the 19 year old punk (aka me) and nothing was done about it. Their ruling basically stated that the cops could do anything they wanted regarding a search with "probable cause". We all of course know this isnt the law, but dont expect them to uphold it any more than everybody else. It seems comfortable to say "you have rights, they cant do such and such". But when it comes down to it, some of them WILL do what they want and WILL get away with it. I could probably write a book over these types of examples.

In other words, dont keep anything in your car you dont want found

 

They are cracking down in some areas:

https://www.scionlife.com/forums/viewtopic.php?t=76897

 

well dang that sucks