and according to "dyno proven" results, hitting 200hp, atleast to the flywheel, of of NA s4 isnt "that" hard.

i was making myself a parts list as i do frequently and got so bored i thought i would add up all the HP gains websites say we get when we buy their product.

heres how i figured it out:
stock:146FWhp so like what ~130 to wheels ish...
apexi says +17hp for N1, i dont buy it, so lets say ~+5
bonez intake COLD air: ~+6
pulley kit: +10
header and highflow cat: ~+10

and finally a streetport: ~+20%

=thats around 192 now i dont know if the manufacturers get their rating from flywheel or wheel HP but still. not too shabby

anyone have anything to add? or am i totally wrong?

 

Id say thats close. Maybe a bit high. Perhaps 185ish...

 

How can you not buy +17HP for the N1, but you do buy +10HP for the pulley kit? :P

But you are correct : it is possible to hit 200HP at the flywheel in an N/A for not too much, keeping it pretty streetable.

 

you will easily get around +15hp for the N1 exhaust....if you want your ears to bleed and an unlimited supply of flames

 

That's similar to the math I came up with before I joined this forum.

I figured:
Stock RWHP: 135ish
Headers/cat replacement: +10hp
Catback: +10 hp
Intake: +5 hp
SAFC: +10 hp
Streetport: +20%

RESULT: 204 RWHP....and about 235 to the flywheel...but according to the dyno results posted here is isn't quite so easy as that.

 

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Turbo +30% and sounds bad ***! Dont blame me if you want to spend your next 4 paychecks on your car now haha

 

trust me if i had the money and time to turbo my NA. i would do it in a heartbeat. but i dont even have a job, yet. by today i should. sucks being a student.

shane racing they actually put it on their rx7 test car. so thats why i believe the 10hp from the pulley kit. but doubt it. just for numbers. and 17 hp from just a catback. no way.

NA FTW...till i can get turbo FTW

 

i don't even tell my turbo customers +20% for a streetport, what makes you guys think an n/a gives you an added 20% horsepower?

 

i forgot the site, but thats what they say around what you can get. ill try to find it again.

 

Pineapple racing sells radiused sixth port sleeves that should improve horsepower, you could also port and polish the TB.

 

i always thought a street port added like 30-40hp.. did think that was alot of power to gain from just a port. i guess i also might be thinking of a wild streetport.

 

Don't forget that power train losses also go up.

For example, the typically FC has around a 20% power train loss. So if you increase your HP to 200 at the flywheel, you will be down 40 HP at the wheels.

But with the stock 146 HP, you will be only down around 30 HP at the wheels.

 

Straight from the Atkins Rotary site:

"What does your "Mild Street porting" do for performance, drivability, and horsepower?

It gives you approximately 20% more horsepower without any significant problems in drivability."

http://www.atkinsrotary.com/index.php?pag=8

--Alex

 

You can't just add up HP claims, it doesn't work like that, there's diminishing returns the more you do to it.

 

i was just saying according to what the manufacturers say. after adding them up. thats why people "SHOULD" have to the flywheel area.

 

i think 30 thats kinda steep. sti's lose 50hp going to 4 wheels according to a subaru tech. so 30 hp to the rears might be a little too much unless its been proven on the dyno. i would think 20. but i could be wrong you are a lot smarter. lol

 

Actually, I think it works the opposite way. For example if you add the intake and exhaust on a stock ported car it would have some gains, but they would be more with a large streetport since it needs the better flow more than stock.

Also, wouldn't an NA see a larger % of gains from porting than a turbo car? I don't know if I'm right, but it seems like the larger ports would be more advantageous with an NA since it doesn't have a compressor slamming air into the engine.

Edit: I think the standard is 15-20% drivetrain losses for our cars, so 30 seems maybe a tad high for stock, but still pretty much in the ballpark. BTW, STi's have 300 FWHP, so 50 hp loss is right in the 15-20% range.

 

Yeah... you might as well assume a car will do 500 HP with the stock turbo at 24 PSI just because it'll do 250 at 12 PSI.

HP claims mean nothing until you have it on a dyno... I wouldn't even bother trying to calculate my car's HP since realistically it's probably no more than 5 RWHP more than stock (...feels plenty fast in when it's in a good mood though...even in 5th gear, at a reasonable 5th gear speed)... and that's ignoring the fact that cone intakes without head shield usually lose power.

 

Try more like 70hp.


Subarus, and most AWD cars, typically have about 25% drivetrain loss for the manuals and closer to 30% for the automatics.

A stock 300hp Sti typically puts down about 230 awhp.

 

Well the typical dyno run for a stock S4 non turbo is around 110-115 at the rear wheels

With a stock 146 HP when new that would put it a little past 20%

On the S4 Turbo (180 hp new) typically has rear wheel dyno runs of around 140-145 HP again, putting it right in line for a 20% drive line loss.

 

right on im picking up what your laying down.

 

what about fuel injectors or something with fuel can you tune it really well with a port and polish of the intake and throttle body.

 

and who sais Atkins has done before and after testing of their ports for exact gains/losses? in my view they just guessed like everyone else does and figured 20% sounded good.

 

You also have to remember that if they even put the car on the dyno to "prove" the gains, they'll take the very best after run and compare it to the very worst before run to get a better number. There's been claims of 30hp from an exhaust on a Honda, in the very fine print they mentionned that it was a ~400hp turbo car, so not a realistic picture of what it'll do for a regular car.

 

Its Atkins, Im sure they have done before and after testing. Their profession is rotarys. They must do some tests.