Carloverx

iTrader: (26)

I went to the drag strip last year and turned some pretty bad times (~13.5). I had an air filter and boost controller set to stock at the time.

Next, AFTER installing a ported manifold, 02 housing, down pipe, high flow cat, cat back, tires and act clutch, i went to the dyno where i initially made 302awhp (turbo trix).

By the time i left turbo trix, i was making 343awhp (I specifically asked for a conservative tune).

I went back to the track last friday and did this:

60'------------ 1.747
330-----------5.512
1/8------------8.008
MPH-----------85.42
1000----------10.460
1/4------------12.555
MPH-----------107.27

This was my best et and mph. The car feels good but I assumed I'd be turning a little higher mph?

I know I can get my ET a little lower with some practice at my 60' but should that HP on that dyno equate to that mph (i know that's a hard question to answer and i forget the type of dyno turbo trix has, but ballpark it).

-Does the fact that it's a 6 speed make that much of a difference?
-Does it matter that i had about 40 extra pounds in the car (baby car seat, stroller etc )

Any info would be greatly appreciated

(on a side note, anyone who's in the central jersey area should go to this https://www.evolutionm.net/forums/sh...d.php?t=345523 )

Thanks

recompile

iTrader: (38)

343awhp should be good for a much higher trap speed than 107... probably 112-114.

Are you shifting at 7K? How quick are your shifts? Are you finishing in 4th? The MR 4th is good for about 113mph on the stock rev limiter, so there's no need to go to 5th.

I would log 3rd and 4th gear to see what the deal is.

Warrtalon

iTrader: (6)

My guess is you're shifting to 5th when you should be riding it out in 4th. Don't shift to 5th - you're not fast enough to need to. Shift at around 7k in the first 3 gears, then hold 4 through the trips. You should be seeing 112-113mph with 343whp on the TT Dynojet unless your car is overweight.

PS. You will only see 110-111mph traps if your rev limiter hasn't been raised from 7606rpm (stock). Maybe 112, but I never went over 111 and mostly hit 110s back before I was ever flashed.

Carloverx

iTrader: (26)

Thanks for the feedback.

1. I was consistently using fifth but I think I may have stayed in 4th on a pass or two without any higher mph. Either way when I go back next week, I will stay in fourth.
But, here's another factor that may be important:

I'm running 245/40/17 tires. (BFG KD's) which have a slightly smaller diameter over stock (about 8mm). How much could this be hurting me? And if so, any recommendations on how to correct it?

2. How big of a roll could tire pressure be playing here?

I was running around 27 pounds in all four. The car felt good other than some slight wheel hop at about 3/4 the way through first gear (i know that's deadly for evos). I recently put them up to 35 pounds for testing on the street and around turns they make substantially more noise and obviously have less grip.



I'll pull some weight out of the car, try to stay in fourth, maybe play with tire pressure, and make sure to shift earlier in 1-3 (~7k)


Thanks again for all the helpful input

Warrtalon

iTrader: (6)

1) It will make you run out of gear sooner and thus reach lower max MPH levels than a stock tire by the time you hit the rev limiter.

2) Tire pressure slows you down as you lower it, but 27 is really nothing. I was running 20psi in all 4 this past week and trapping 114-115 at altitude, and that was my highest ever. The lower pressure will help your 60' and overall ET more than it will hurt your MPH.

Mr. Evo IX

iTrader: (5)

Carloverx, Great ET for that trap! That run doesn't look too bad to me (60 + ET), are you sure you didnt lift before the timers? Also, the trapspeed is an average of several timers at the end of the track.. not the highest mph achieved. I agree you should be trapping higher. Tire size can play a role as well. I have my rev limiter at 7800 and trapped 113, but ran a 12.7.

Warrtalon, why would you recommend short shifting 1-3? I'm really curious.. not looking to start a fight.

I'm aware of the common logic that our turbos dont produce enough air above a certain rpm and that torque drops off but wouldnt the lower gear ratio still provide for faster accelleration even if power fell off somewhat.

Here's some other logic. Even in the closest jump in transmission gear ratio, the power at the RPM that you drop back to is less than that which is available at higher rpm in the previous gear, plus your throwing more load with the taller gear. In other words everything that I have recently discovered about drag racing manual transmissions says the optimal shift point is the highest RPM you can safely run without hitting the limiter (that will cut power) because when you consider the gear ratio you will always have more accelleration in a lower gear.

Also, I've previously followed the 7K rpm shift point 1-3 guidance and have gotten high ET's for my trapspeeds, tonight I"m going to try not shifting till closer to redline, 7500 all gears except 4th.

Carloverx

iTrader: (26)

Thanks again for the feed back. I'm going back to the track June 7th and am going to try different shift points. In the mean time, maybe this will help?:

Mr. Evo IX

iTrader: (5)

http://www.dsm.org/tools/calchp.htm

I'd say your on the edge of the ballpark depending on how much you and your car weigh.

Did the boost level change? What was the temp / relative humidity at the track? What was the wind speed / direction? All these things are variables that you have no control over. If you want to know if your down on power or you think something is wrong, you should go check the car on the same dyno and see what's going on. Otherwise, I agree with you.. more practice and experience will net results, hopefully you dont break something during the learning curve. A dyno is a tuning device, it in no way guarantees that your going to run a certain time or even that the car is actually capable of running a certain time (although you can generally get an estimate).

Temperature alone is huge, my car on it's current tune with ecu controlled boost runs 25psi when the temp is 70* or under but today on the way home with temps in the high 90's it's only about 23.5psi. The difference in whp between those two conditions could be 10-20whp. I know at our dragstrip sometimes you might be in staging lanes for an hour and underhood temps get high. All kinds of things can affect your car's performance. Of course the biggest variable at the dragstrip is the driver.

Carloverx

iTrader: (26)

At this point, i'm confident i can drop 40lbs out of the car. That should be good for one more mph

Did you run at the track last night to test the different shift points?

4DR

iTrader: (27)

Shift faster. With 330+ hp I ran 12.3 @108. My mph sucks, but I raped those gears.

I had nothing in the trunk (stock wheels/stock tire pressure...etc.)

Mr. Evo IX

iTrader: (5)

I made it to the track and ran my best ET so far this year, which is not spectacular because my trap was much lower than usual, but I only got to make 2 runs 12.8@107 and 12.5@109. The first run I attempted to run out the gears longer, actually bumped the rev limiter in 2nd which caused knock through 3rd and 4th and a slow time. The second run I tried to shift earlier but all the shifts in the log were at or above 7500rpm so I really dont have the low rpm shift data. I didnt get to make a 3rd run. The Red Evo was shifted at 7600 every run and Alex improved his times throughout the night 12.5,12.4, and a 12.3. wth pretty much the same 60ft 1.8 and trap 111.

A quick look at weather underground for last night could reflect the differences in the times. Note the 10 degree temp drop and wind reduction. and the 60ft improvement.

1st Run 12.861 @ 107.827 1.765 7:45 PM 87.8 °F / 31.0 °C 66.2 °F / 19.0 °C 49% 29.97 in / 1014.8 hPa 7.0 miles / 11.3 kilometers East 13.8 mph / 22.2 km/h / 6.2 m/s


2nd Run 12.586 @ 109.498 1.725 10:25 PM 78.8 °F / 26.0 °C 69.8 °F / 21.0 °C 74% 30.03 in / 1016.8 hPa 10.0 miles / 16.1 kilometers ESE 6.9 mph / 11.1 km/h / 3.1 m/s

I would say the limited testing was inconclusive but I'll give Warrtalon and his method the benefit of the doubt until I see conclusive evidence otherwise. It was more a bench racing theory/question and I dont feel that it's been proven on the track yet. Plus Warrtalon has lots more experience drag racing the MR transmission than I do. He generally speaks from experience and knows what he's talking about. Since the MR tranny has close ratios it may even be mathematical provable that 7K is better.

*Edit.. I started a new thread and posted a graph/log for shift point discussion.

Warrtalon

iTrader: (6)

Mr. Evo IX, I didn't say to short shift - I said to shift at 7k, which is very normal for a stock turbo Evo. I've been doing this for over 3 years, and I raced with the 6spd hundreds of times. It DOES depend on the powerband, but typically if you shift around 7100, you will start the next gear at ~5500. 5500-7100 gives the most average HP. You don't want to shift at a point where you're already at peak hp in the next gear. You want to straddle peak hp so that your average hp through the gear is highest.

Mr. Evo IX

iTrader: (5)

sorry for the misquote. You read me right though, I was asking why you recommend shifting at 7K instead of higher.. did you see my other thread that I started?

https://www.evolutionm.net/forums/sh...d.php?t=348461

Warrtalon

iTrader: (6)

Yes, just don't feel like writing a novel. I've addressed this very topic many, many times in the past beginning 3 years ago, so I am lazy about re-typing it.

steinvb12

iTrader: (4)

That is a very well put statement. And I've expereinced similar results....