Last weekend there was a dyno day for Rx7s in Fremont. Luckily they allowed me to dyno my 1998 GS400 with 58k miles. I have seen the dyno graphs from swiftracing and the HP & torque rating are very similar for my run. They also hooked up a wideband A/F to exhuast.

My buddy also let me borrow his OBD-II scanner. With it hooked up , I was able to monitor and capture all the sensors real time while dynoing. Pretty neat tool for datalogging.

The first and second runs were back to back. The 3rd run had a 5 min. cool down. On the 3rd run, I removed the top air box cover and turned it toward the fan. Would it increase HP like a cone filter?? It definately made more roaring noise. But the HP was exactly the same!! Unfortuately I didn't reset the ECU.

The OBD-II scanner said that on the first two runs the air flow was 6.X lbs./min and the last run without the filter was 7.x lbs./min. So the engine did inhale more air but no extra HP? The A/F ratio was exatly the same.
The only explanations that I have are:

1. heat soak from the engine.
2. Timing was retarded a bit.
3. Isn't 10.9 A/F relatively rich?? I think 11-12 would be much better.

Dynojet aren't the best since they are based on inertia. If I had lighter wheels, the HP reading would go up. Oh well.

-Jeff

 

Jeff, thanks for posting your results. Your car is totally stock?

Interesting how the first run is the strongest. I don't know much about dyno ptotocols; I guess because the car was not 'hot'? Did anyone give you any hints as to that outcome?

 

I had my 99 gs400 dyno'd back in Feb 5th, 2000. At the time I only had Borla exhaust and a k&N airfilter replacement (stock airbox). I had two runs. and I both hitting about 252 lbs of torque at 5800 rpms. Since that time I have added Swift's intake system. I feel I picked up significant power, however I have not had it dyno'd

 

the same old question always seem to come up..

also
I hope you mean 252hp (or if it was torque, I doubt it peaked at 5800).

 

Yes, you are correct it was a horse power run. The run was done in manual mode with the traction system turned off and I believe it was third gear.

 

I had my GS dynoed 10 times!!!! lol And it kept gaining HP!!! lol

Actually it was getting tuned, and I was running too rich!
But usually the 1st dyno will be your strongest if you continue with a 2nd, 3rd, and 4th dyno without any adjustments.
Factors include: 1) Engine Heat 2) Cool Air Flow 3) Air/Fuel ECU adjustments.

I have seen cars gradually lose HP (1 to 4 hp) each time they dyno, but gain it back after a 20-30 min cooldown. I also think if you would have reset the ECU, and then removed the airbox, you would get a little increase in both HP/Torque. IMHO.

Lee

 

O.k. guys, First I will say that I am an ex-1st gen G3 owner,, NEW G4owner...

(That was my disclaimer of ignorance for the next part...)


Now I gotta say I am a little bummed that the difference b'tween our flywheel h.p and actual rear wheel h.p.

I mean, am I correct in believing the "advertised" Lexus H.P. figures for the G4 (300HP) is most likely the flywheel rated figures?
That's what I always assumed, and if thats correct am I seeing that accd'g to the dyno figures we're losing approx 70hp to the rear wheels??????

I knew there has to be a loss b'tween the two, and I would have told anyone at the bar I was making 250-260 hp at the rear wheels in stock form.... But barely 230hp...????

C'mon guys, I really love my G4...Pump me up here!

Now b'fore ya think I'm a mechanical dolt I gotta tell ya all that I have dyno'd my 911 Carrera and it only has a 3.2 ltr, but its been blueprinted has full headers/racing hi-flow muffler/race mode chip/K&N Cone..blah blah and it came away with an avg of 222 rear wheel h.p.

Anyway...

 

ocnbrzz, the GS averages a 22% drivetrain loss(give or a take a couple %) which is on par for an automatic. Is your Porsche a Manual? They have a lower % of drivetrain loss than autos at around 15-17% if I am not mistaken. So the GS's % of drivetrain loss is normal for an automatic.

 

Yeah, I know, you are correct, I never really crunched the #s.

I guess I was hoping for better transfer of power thru awesome Lexus engineering!

Thx for the info!!

 

From this weekend's Charlotte meet I dynoed mine as well. Haven't been able to get the software to work to grab a good graph, but I have the printout.

Results on my best run (my other runs roughly similar) 246.5 max POWER and 286.6 max TORQUE. 76 degrees.

Looked like the biggest boost in performance comes from the Precision Industries Dragon torque converter. You could see a real difference in torque spike at takeoff.

Pic below is Dex's rear wheel (much cooler than my factory wheel).

 

Dyno'd my GS400 with Dave this weekend. I only have the L-Tuned exhaust and drop-in K&N filter replacement.

Got max. 238HP (6000rpm) and 252lb/ft torque (4100rpm) on my best run.

drmanny mentioned 252HP which, without an intake, seems unlikely. drmanny, I think maybe you had your torque and HP numbers mixed up.

Anyway, from watching 4 GS400 dyno runs, it seemed like max. torque was dependent somewhat on driver 'technique' to some extent, although Dave's run seemed to validate the improvements through the Precision TC.

Definitely an interesting experience!

And our cars sound *VERY* loud when in an enclosed place at redline!

And yeah, I didn't get my foot to the floor quick enough in the runs below... it's tough to do it without downshifting from 3rd to 2nd. (All runs were in 3rd).

 

very awsome!!

you get to drive your own car on the dyno? hm... i never knew that!!

 

im looking at this graph and the TQ makes absolutly no sence... i mean it hits 400TQ?? someone wanna explain this to me? im sure its an instentanious thing that cancels out or something but where do you get max TQ down low from?? werid

 

also... torque is supposed to be an equation figured out by HP and RPM.... TQ should always cross HP at the same RPM and it doesn't in this test..... its supposed to cross at 5200RPM or something.... man im confused... only the HP makes sence to me

 

just studing it more.... i see that the first dyno is exactly as i thought, the TQ crosses the HP at 5.2xx RPM!!

all of them cross at the exact RPM, this proves what im saying... this TQ dyno makes no sence!!?! please explain.

sorry for all the posts... i keep discovering new stuffs