Where have all the pretty horses gone?

[Franz]

I would like some advice please. First off, my 2003 SRT has had about every TSB and recall problem that is out there. (Including the valves). I knew I had problems when I first drove it because it felt underpowered when compared to my slightly modified 95 RT. Unfortunately, this was only SOTP and not dyno proven. After all the work by the dealer, I had it dynoed and needless to say, was a little disappointed by its mild performance. Although, after the valve work it did feel stronger to me. Is the RWHP of about 415-420 within the range of what is accepted? It seems as though this is the lowest RWHP listing I have seen. I ran the dyno on two different days and two different machines and got the same numbers. My guess is that it is the A-F mix because the graph drops off the page. Any advice would be greatly appreciated.

Thanks.

 

[Mike Adams]

Two we dyno'd at dyno day in Ontario where about the same as yours give or take 3 hp

 

[Viper Specialty]

Two we dyno'd at dyno day in Ontario where about the same as yours give or take 3 hp

Yes, my car dyno's at 420/465, and Jerry's car dyno'd at 421/460.

I was not surprised though personally, as I broke my car in until 1000 miles, never hammering on it, and then drove to the Dyno at 1010 miles, never hammering it again because of the rain that day, and put it on a dyno. Drive like a wuss, dyno like a wuss. I got what I had deserved. I am holding out for a while and getting another baseline after I allow the PCM to relearn a little more. Jerry blames his numbers on a similar scenario.

One thing that did cross my mind, though I cant remember for sure because I never paid close attention to it... Does a Dyno take overall tire diameter into consideration? if so, I didnt see the guys at the dyno change the settings from when the Gen 1/2 guys went. that hiccup would certainly account for the missing HP, as an SRT is overall comparably geared at 2.93 as opposed to 3.07 on a GTS/RT.

 

[CHAD]

No input needed for different gearing.

You will see a little mechanical loss from numerically higher gears (which does not apply in this case) but the number seems to be small.

Chad

 

[GR8_ASP]

Is the dyno a Mustang? If so that would explain the difference.Mine dynoed just 445 RWHP stock (Dynojet).

 

[Franz]

Both of the dynos were dynojets. My 95 RT put out 400 RWHP with a predicted 460 at the flywheel (with the minor mods that are on it) the same day.

I just get a feeling that most of the stock SRTs are like yours in the 440 RWHP range.

Could adjusting the A-F give 20 HP? Anyone have any experience?

 

[GR8_ASP]

Yes, f/a reduction would net power. But that does not answer the question of difference car to car. I suspect the difference is air flow related and fueling. If the air flow were to increase you would net higher power and lower f/a. I suspect that as I do not believe that much of a change occurs due to injector variation.

If it is flow related it could be anything including intake manifold, port matching, ports, valves/valve seats, exhaust system, cam timing, etc. Happy investigating!

 

[treynor]

Interesting. FWIW, my SRT/10 had the same "rich as heck" behavior on the dyno, and it made 475 RWHP SAE with ported heads. The "normal" range for the SRT seems to be 430-450 RWHP stock.

Question - had you changed anything recently on the car, or unplugged the battery or ECU shortly before the dyno pulls?

Also - try going to the dragstrip. With a few runs worth of practice, your trap speed will let you know if you're making the requisite power.

 

[Viper Specialty]

TREYNOR- Neither I nor Jerry had unplugged our ECU's to relearn before the Dyno, this was a big cause in my opinion...and the 100% humidity didnt help either. Nothing related to HP had been changed on either car recently.

We are both keeping our cars the same configuration as before, except we are going to do the ECU's- and go get another baseline in a few weeks. It definatly would be worth the money and time to see the outcome, and since two cars are involved, it can be averaged out to get a better idea of how much an affect the ECU relearning really has.

 

[George Murray]

Soooooo....the taller SRT-10 rear tires equate to a 2.93 final drive ratio when compared to the Gen 1 & 2 cars?

 

[Viper Specialty]

Soooooo....the taller SRT-10 rear tires equate to a 2.93 final drive ratio when compared to the Gen 1 & 2 cars?

correct. If you put 2.93's in a GTS, you will have the same speed in gears as an SRT w/ 3.07's and the taller stock tires.

 

[George Murray]

roger that...thanks for the numbers...I suspected something like that.

3.54 gear on the way soon!

 

[Viper Specialty]

Another tidbit of interest... 3.55 gears in an SRT are equivalent to approximatly 3.38 in a GTS... which is about as close to "perfect" as you can get!

 

[George Murray]

Nothing like discovering the gear sweet spot...

Anyone know what a 3.54 ring and pinion costs for an SRT?

 

[Franz]

Has anyone dynoed their '03 "valve issue" car after the fix? What were the before and after numbers?