Bliggity

50 degrees, just rained. Did three runs, two when I got there and last one we waited for 20 mins to cool and ran it again, last run was the strongest. The dyno I used was a Dynojet, is a dynojet pretty realistic numbers, I know some are higher than others and didnt know how a dynojet ranks. Drum roll....JK, wish the numbers were higher but........

253.2 WHP

281.5 WTQ

I am running a srt intake/ecu, straight pipe where resonators were removed and magnaflow mufflers. And some 19's. I will get the printout loaded soon.

What would the huge drop be around 6k rpms, dyno guy said may be torque converter?

speedaddic

iTrader: (10)

nice #'s...dynojet is inflated. Most accurate is a Mustang Dyno..Mustang is usually 17% less hp than a dynojet.

JeffTsai

iTrader: (1)

I don't think it's purposely inflated. Dynojets just use a different kind of loading technique compared to the Mustang dynamometers which causes them to read higher. Well...then again they could of designed it that way to make prettier numbers lol. I wonder what kind of system manufacturers use to rate their cars from the factory.

Bliggity

Great question, I'd like to know that myself. What lb injectors do I have stock? Open or closed circuit fuel?

KiPod

iTrader: (31)

Most manufacturers rate their cars at the crank, not at the wheels.

speedaddic

iTrader: (10)

I think that's an obvious statement that Jeff and I know ...I think he means how do they measure the horsepower of the car/motor...what type of dyno is used to figure the # number they come up with...

KiPod

iTrader: (31)

Thats the thing, I havnt seen any manufacturer list whp #'s only crank. Manufacturers want to use whatever gives them the biggest # so they can sell and make money.

JBrady

While not perfect the dynojet has become the standard for measuring rwhp. As long as all things are kept consistent I have no problem with this. The variance between engine "rating" and rwhp/rwtq (tq reading adjusted to engine RPM) has become a reasonable predictor of actual performance.

I have seen the "dip" around 6000rpm on other Lexus V8 dynos. It may be the knock sensor(s) hear a harmonic at that point and pull timing momentarily. It could be that the locking clutch on the torque converter gets released and then re-engaged momentarily. If RPM could be broken out and engine acceleration mapped for this area we could know more. If the RPM rate slows then it would be engine power (timing or other) if RPM rate increases during dip it would be drivetrain (converter or other).

253/281 are good solid numbers. Wonder what baseline is. BTW, I like that the operator was able to measure from 2500rpm. What gear?

I would love to see this car with headers... and so would you!

VEGAS DRE

before lastnight did you get a chance to dyno your gs before you did the mods to it? just wondering since your gs430 laid down 20 more hp/almost 15 more tq to the wheels than my 02 gs 430 on the same type of dyno. but the only mod that i have that i shouldnt even call a mod is a k&n drop in filter.

Bliggity

Thanks, really good info! 4th gear pulls. I am in the works with a local CL member to buy his headers this weekend, if it works out as planned I will take her back next Thursday to the Dyno.

sam430

iTrader: (10)

Which header would CL members recommend?

speedaddic

iTrader: (10)

S&S headers...I think they're the only company that makes it for the GS4...I've got the only set of JPI headers....

this thing is screaming for headers...you'll love it

sam430

iTrader: (10)

Question on Smog. I live in California, what do I have to do to pass smog if I install the SS header? Do I have to swap the old header back in?

edit** I guess it'll pass smog.

macd7919

iTrader: (10)

As far as the huge drop question, did the guy give you a printout of the air/fuel ratio? You really need that on the graph to make sense of whats going on and see if there is more power to be had.

evil00017

I asked this question awhile ago and was told that the stock heatshielding should fit oveer the s&s headers. If you put that on put your stock cats on the inspector probably wont notice they are aftermarket.