JBrady

Lee,

First of all congratulations on SC'ing the 400

That said there are some strange things about your dyno sheet. First of all, you seem to be WAY down on power in the lower ranges even compared to a stock engine. At 3500rpm a stock engine makes around 150rwhp vs. your charts indicated 100rwhp. Torque peak on a stock engine is 4000rpm and the stocker is around 180rwhp vs. your chart indicating 120rwhp. In fact your chart does not beat a stock engine until 4900rpm and then only by the margine of error. Notice I said INDICATED because if you were down on power that much you would DEFINITELY feel it.

If this were my car I would want to get the tuning looked at and double check my numbers on another dyno.

Pearlpower

iTrader: (2)

As much as I would prefer to dyno the car on the same machine for comparison sakes, I will be headed to another dyno the next time around. I was not very impressed with SP Engineering. Everybody trying to commit suicide by smoking and then even around me. Hot as hell. People walking all over. I understand they have a business to run, but geez! Showroom was the same though a bit cooler.

As for the other numbers, he had to baby the pedal down low as to prevent the car from shifting, thus explaining the lower numbers. Not sure how many GS's he has done. The video also supports this as he lays into it very easily and does not hammer it till if he does at all at top.
Anyone know of somewhere else other than XS or SP in So Ca?

Lee

JBrady

Lee, that explains everything. Part throttle the car will run close to stoichiometric (the theoretical air fuel ratio that allows all the fuel to burn). BTW, this varies with fuel type but with gasoline is 14.7 parts of air by mass to 1 part gasoline by mass.

Also, for those reading, dyno's rarely load an engine to the extent that real driving will and therefore tend to show a RICHER A/F ratio than actually is seen. So, be careful when tuning on an inertial chassis dyno such as a Dynojet. True, you can "make" bigger numbers on the dyno by tuning lean... but on the street you are dangerously lean.

As far as Lee's dyno goes, since the operator was not able to give full throttle below 5000rpm or so the lean numbers are not important as the load is lower. Once under full load the ratio drops as low as 11 to 1 and then eases back up towards 12.5 to 1. This is fine. Get that belt stable and not slipping and the blower will continue to increase boost with RPMs. That will give the steady power increase seen in Jaime's and Dave's graphs.

Of course ALL of these cars need better exhaust manifolding. If we can just find someone willing to get good manifolds made...


In all fairness, good manifolding will really wake up these FI cars.

Yeah, yeah... I am working on it.

RMMGS4

iTrader: (5)

Thanks Jbrady for your "always informative" responses. I ran a dynojet on my NA car and they said I was already running on the lean side. Your statement of the loading ,scares me that my car is running dangerously lean under real world conditions. I'm gonna have to dig up my chart since it is no where to be found, but all I can say is on the same day two other GS's were reported to be running on the rich side. Don't know why my car is not running the norm??

Pearlpower,
last year we dynoed at a shop that normally does Hondas and our TQ numbers were below stock. The same three of us ran again this past year at another shop and got way better numbers.

I always suspected that the first shop was *****footing our cars because of being used to running low TQ vehicles like Hondas. I think jbrady confirmed my assumptions.

I think we gotta tell dyno shops about this concern. Unless the tranny is kicking down right on the dyno, then tell these guys to jump harder on it !

You are probably right that your dyno $$ spent at SP was a waste of time.

Good luck finding another shop. Since I am in NorCal , I can't help.

Pearlpower

iTrader: (2)

Spoke with Mo at SRT today. He suggested that I get a new Walbro fuel pump which I went ahead and ordered from him. He indicates that the car appeared to be getting leaner at high rpm's which it is according to the above, though it still appears healthy. Still, I would rather have a HD fuel pump to be on the same side. Once in I will redyno the car and then ECU flash if need be.

SO.......anyone know of a good dyno shop in So CA?

thank you
Lee

JBrady

Dyno's will vary as will the engines actual output depending on how the ECU is reacting to all the variables it monitors including knock whether real or triggered falsely. My car definitely makes different under different conditions often even from run to run. Fuel quality is very important. Driving style also comes into play. Of course my car is stock so modified cars create the potential for a greater variable.

Over 2 years ago Mo told me that there is a trick to dyno'ing these cars but he didn't want to give details. Obviously Dave and Jaime and others have dyno'd correctly... were these done at SRT or elsewhere? It would be valuable for this "trick" to be understood and shared with others so that people not in SRT's area can get more accurate data. I cannot believe it would cost SRT any business if they were to share... what do you say Marken? Mo? Anyone else have this "secret"??? Come on and share it.

DaveGS4

iTrader: (2)

The difference is that Mo locks out the torque converter so you don't get a spike in TQ readings. The secret is how he does it via the ECU which I can't explain in detail, but he's showed me the differences in dyno with and without.

I dyno'd NA at four different places - SRT was the LOWEST of all the dynojet dynos (the mustang dyno was less, but different type) due to their approach, but results were smoother on the chart. SRT is the only place I've done FI dyno so far after the install for tuning.

Also FYI - Marken doesn't work for SRT any longer.

DaveGS4

iTrader: (2)

I just cracked open my new PI TC torque converter box and there is an interesting piece of text that may apply I'll type here.

USING SMALL DIAMETER TORQUE CONVERTERS WITH DYNAMOMETERS

There is a misconception that poor vehicle performance numbers on a chassis dyno are the result of an inefficient torque converter. This is totally false, and the following facts are why you should not believe the numbers the dyno is putting out.

All late dynos have a software program that commands the load and speed of the vehicle over a certain time period. This program will work well if the torque converter clutch locked when the run is made. However, in the case of an unlocked torque converter, the dyno reading will be incorrect. With this type of dyno programming, the low speed output torque of an unlocked torque converter will read high due to a good torque converter's high torque multiplication. The higher speed torque output will be adversly impacted due to the extended length of time the dyno program takes to allow the torque converter to reach the transition from partial torque multiplication into the hydraulic lockup phase of operation. These dynamometer readings are totally bogus when using a small diameter torque converter unless the dyno program has been rewritten to compensate for the torque converter being run unlocked. This program never takes place when the vehicle is being driven or raced normally.

If a torque converter has a very poor torque multiplication, it will appear to give better output numbers on the dyno than one with good torque multiplication. However, the vehicle performance on the street or track will show the torque converter with the poor torque multiplication to be inferior.

DaveGS4

iTrader: (2)

Damn I typed all that and then I found mostly the same thing on their website

http://www.converter.com/whatsnew_dynamometer.htm

FutureGS400

I have decided to forego having a dyno session on my car. So many variables, including the dynos (and operators) that I'm not even going to spend the $$$.
I will quantify my performance gains at the track -someday soon I hope- which is what really matters anyway (i.e. where the "rubber meets the road".)

That said, I do recognize the usefulness of a good dyno session for tuning purposes -especially for those going FI. Good luck on your tuning and dyno runs Lee. Wish I could help on a good dyno location in So Cal.

Pearlpower

iTrader: (2)

I installed my new Walbro fuel pump last night. So far so good. Car does seem to respond quicker, but that is most likely due to the much cooler weather that we have been blessed with in the evening. Feels a little stronger at top end which could be the new fuel pump.

Anyhow, SRT wanted me to redyno the car once the fuel pump was in place so that they can properly recalibrate the ecu.


Place: Rage Performance
5637 Arrow Highway Suite J-K
Montclair, 91763

I am hoping to better the dismal 331rwhp in the previous dyno session.

Lee

CinFulxgs

I can get 3 Dyno runs here in Tampa for $40.00. Is that a good deal?

Pearlpower

iTrader: (2)

That is an excellent price. Rage is charging me $50.00 for 3-6 runs with A/F readout. SPengineering charged me $100.00 for 3 runs and a good dose of second hand smoke.
Go for it.
Lee

rominl

iTrader: (4)

i can't wait to see more results from you lee!

Pearlpower

iTrader: (2)

I went to Rage Imports today for my second dyno. SRT wanted another dyno as I installed a Walbro 255gph fuel pump per their recommendation.
First off, I highly recommend Rage imports. 6 runs for $50.00!!!!!!!!!!!!!!! with A/F readout!! Not too mention the guys there are really cool and actually speak meaning they answer questions unlike the previous place where I could not speak to the dyno operator.

Shop was clean and professional. Plus the air was breathable!

Several runs were made. Car did better than before, however as you can see in the graph below, it is still very lean down below (expected) and VERY VERY rich up high. Went off the charts in fact. This is would explain why the car pulled numbers all over. Best run was when car sat for several minutes and tested. The last run on the graph was done in 2nd gear as they wanted to check some things. Best run netted 345RWHP or 431 crank HP SAE corrected of course. Temperature was much cooler this time around.

I will get this over to SRT so that I can get the computer reflashed. Expect another dyno in 2 weeks.
Lee

VIDEO-right click and SAVE to your drive

http://www.tundraworld.com/sessionII.wmv

video is 12megs long. A bit shorter than the 24.4 of the first video which is good as it was downloaded over 260 TIMES!!!!!!