SRT Versus GTS

GR8_ASP

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This is a redo of a previous thread on this topic. There will be no mention of any side by side comparisons. Period!

This time I have calculated the thrust for both the GTS and SRT based on real dynomometer measurements, using the effective rolling radius of the tires measured on the dyno. This information provides an excellent explanation of why the GTS and SRT are nearly side by side in 3rd gear up to 5000 rpm (in the SRT).

To do this I have used dyno measurements from my SRT, which has fairly typical results (437.3 RWHP and 473.3 RWTQ) and David Meyer's (thanks David) GTS (410.2 RWHP and 450.3 RWTQ). The data from David's GTS are with the air filters removed, thus representing a best case K&N filter installation.

I have graphed the rear wheel thrust versus vehicle speed. The thrust is directly related to the acceleration force of the car. Resitances such as wind resistance and rolling resistance are not incorporated. This is important as the GTS has a drag benefit versus the SRT and the RT/10 has a deficit versus the SRT.

Conclusion. From a roll in the same gear the GTS is roughly equivalent up to 5000 rpm. But, because of a slight advantage at around 65 mph (3500 rpm in the GTS), the GTS would be in front a little until about 100 mph. From there the SRT would walk away due to higher thrust for the remainder of 3rd and a later shift to 4th. Once the shift to 4th is made (assuming that shift is made at 6000 rpm) the SRT will equal or better the GTS thrust for the remainder of the evaluation. Had we started in first the situation would have been the same, with the SRT pulling on the GTS from about 40 mph on. This does not show up on a side by side same gear evaluation, especially if it is stopped before the SRT advantage comes into play.

Looking at my information I believe I now understand a critical flaw many of us have with the SRT. That is the maximum thrust, thus acceleration, occurs when shifting at or near redline. This is a little unusual and much different than the Gen II. You can see this on the graph where the 3rd gear and 4th gear lines cross. That means there is equal thrust at that point. So fellow SRT owners, in the future try taking it up to or close to redline for shifts and see how that helps. Based on this exercize I would say that will make a HUGE difference versus shifting around 5500-5800 rpm (vicinity where Gen II's are likely shifted).

225SRT_vs_GTS_Thrust.jpg


Hopes this helps and let's get out on the track and prove this out with real world information.
 

kenvw

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Thanks for the info very well thought out.
One thing to consider when looking at the numbers these two vehicles are extremely close, In fact the rwhp is only 27 hp diffferent and the rwtq only 23 tq different. This little amount of difference doesn't add up too much so it is easy to see the that the comparisons would be hardly noticeable.
 

Skip White

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Considering the SRT is terribly over geared, as the tire diameter is 1.3 inches taller, these are great numbers. I'm not sure how much difference it would have made, but 1.3 inches is quite a bit in terms of gear ratio. I would say its equal to being between 4th and 5th. It would be good to put a set of GTS wheels on the SRT to get a good comparison of the two cars. I think so?????

Skip White
 
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GR8_ASP

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Skip that is a good idea. But it would require removing the parking brake calipers as they need the 19 inch rims for clearance. But for street driving I agree with most that the tall gearing removes some of the fun to drive potential. I do not know if the new differential uses the same ring and pinion for those that want a new ratio. Anyone know?
 

genXgts

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Hey Ron, great notes of comparison, surely tire size is playing into the equation, nice work!!

Little low on the 97 baseline at 410 though no?? Even my lowly Blue/White eeked out 421 after a three hour drive with K&Ns in place!!!:)

keep up the SRT posts, have to get together for a cruise soon, I'll come over your side, you in??? Maybe even take me for a cruise if your feeling nice!
 
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GR8_ASP

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Hi Ryan. I think this was a fairly representative Gen II. It is real dyno numbers - no fudging. Your 97 sounds pretty strong. I heard 96 and 97 were a little stronger. Everything I have seen indicates my SRT is also on the weak side. Something I would really like to do something about.

Cruises Definitely. Let me know when you are on the north side of the border.

Ron
 

TZL

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This doesn't take into account aerodynamics and top up or down on the srt-10

I don't remember of CD figures on the SRT-10, but i'm pretty sure they weren't better than the GTS.

This would make a difference at speeds above 100mph, I don't know how much of a difference, but probably enough to be noticed.

Ting

...the GTS would be in front a little until about 100 mph. From there the SRT would walk away due to higher thrust for the remainder of 3rd and a later shift to 4th. ....
 
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GR8_ASP

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TZL. You are correct. This is a thrust comparison only. The SRT has better aero numbers than an RT/10 and worse than a GTS. Less than 100 mph the aero is not a big player though.
 

Torquemonster

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Nice work Ron!

I've converted the torque in 3rd gear to get some comparison to newtonmeters which are used on dynos here - the Viper makes around 2170NM in 3rd gear.... which is so far ahead of most V8's and turbo ricers - its in a league of its own. That's a lot of thrust!!!
 
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GR8_ASP

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Torquemonster - thanks.

I have been trying to upload a graph of the SRT with 3.45 final drive gears versus the Gen II (upoad feature not working for me anymore :confused: . 3.45 is the highest that I have calculated that will not result in a serious reduction in top speed. With 3.45's the SRT has much higher thrust EVERYWHERE. Sounds like the ticket to improved driveability and performance.
 
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GR8_ASP

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I have the same first question (compatability of differential gears with previous Dana.

As to thestrength I don't know. I have only heard of a few cars with problems and many examples of no issues. I have been fairly careful so far but have clearly stressed the driveline. Not a full out rev and dump the clutch but a WOT ease the clutch out kind of launch. A week from Friday is the Midwest Rendezvous drag event. We will see then.
 

Viperfreak2

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The SRT feels loose at 140+ with the top down, but VERY stable top up. Anyone else notice this? GTS was stable to 150, then it gets a little scary.
 

Moundir

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My Gts feels pretty darn good doing 175mph a few times and 180mph my highest to date :D
 

Moundir

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What you dont believe me :D I can hit a good 160mph in Yonkers no more, but some highways in Li and 684 are good for 175mph :) For 180 you gotta go thru the swamps of fl :D
 
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GR8_ASP

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Haven't been able to upload pictures so was unable to make this post. I found an alternate source for posting pictures. Not easy for the computer illiterate though.

The graph below is similar to the one shown in an earlier post with shift points added.
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The next graph is the same but the SRT now is with 3.45 rear end gears. What a difference. With 3.45 gears the shift points are a little earlier than the Gen II, but not much. Top speed does not appear to be impacted as thrust is about equal at 185 mph with 3.07 and 3.45 (different engine speeds).
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I am looking forward to the availability of gears for the SRT so we can evaluate this. Looks promising on paper. ;)
 

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