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Modifications - Real World Results for Every Mod - K24s
I bought a 996 TTS in April. It had an old GIAC tune and AWE GT2 high flow cat exhaust. I thought I would log in real time in the real world what each and every modification on our cars is worth (well almost every bolt on mod for K24s).
I have kept detailed records, prices, times, speeds and datalogs for each mod over the last 6 months.
Rather than just jump in a build a car that would take me from 457 bhp to 1200 bhp I thought I would gradually increase the power such that I got used to the handling. My performance measurements are
1. vbox performance box which is good for my 40-80 mph, 60-100 mph, 60-130 mph and 100-150 mph measurements as well as providing Longitudinal Gs which means I can also get EXACT numbers for my brake horsepower.
2. Eurodyne datalogging (similar to Durametric)
The car has been run on the exact same stretch of road with almost the same slope (-1.8 to -2.0%) for consistency (unless stated). Sadly this private estate road is now open to the police so I have to find a racetrack to do further tests as we go along.
Stage 1 - I bought Eurodyne software ($1500 from Chris Tapp in Canada, but Tim941NYC is a USA dealer, great product, really great) and logged the existing tune which was a very old GIAC tune, car was very quick but needed more fuel and a new clutch. Using Eurodyne we flashed it back to stock.
2 gallons E85, 14 gallons 93 octane used on all runs here unless otherwise stated
60 to 130 mph (stock with AWE Exhaust) = 9.2 seconds (4th gear only, no slope, 65F)
60 to 130 mph (GIAC tune with AWE Exhaust) = 8.8 seconds (4th gear only, no slope, 75F)
Then I added the new Eurodyne tune and took the car to a local dyno where we managed to snap the front axles and break the front diff. When the car broke it showed 430 awhp, blessing in disguise
Eurodyne tune over the GIAC tune in AWD mode with AWE exhaust = 8.4 seconds, 85F
Last edited by wolfhedge; Oct 30, 2014 at 08:26 AM.
I was a bit miffed at my stupidity for not double checking the AWD dyno to see if the front and rear were rolling properly but anyway through adversity comes opportunity. I was introduced to Tim941NYC by some of the BMW guys and drove my car with the broken diff down from Quogue to his workshop in Plainview. Impressive yet quiet guy as I have discussed in many threads here at 6 speed.
JoeTwinT , BHT Todd Nall and Tim all had done excellent RWD versions of their ultra fast cars and coming from a RWD background I prefer that feel to the planted fat *** Porker 996 Turbo feel in AWD.
Tim installed GT3/GT2 Ohlins DFV street coilovers with a full GT2 set up, front wheel bearings, perch and top hats from GT3, GT2 uprights ad PCCB hats for proper offset, flush/bleed brake system, add stainless steel brake lines front and rear, Hunter 4 wheel alignment etc. Effing EPIC, car corners like it is on bloody rails and with all of the mods I saved about 100 lbs in dead weight = MOAR POWER and better speeds.
I drove it as is for 1/2 a day and then sent it back to Tim for an upgraded clutch and new fueling system.
I did crack off one 8.0 second 60-130 mph on the flat with the RWD in 4th gear (dog ate my homework as I cannot find vbox chart) before getting the fueling done, so I guess the RWD is worth 0.4-0.5 secs off 60-130 mph over AWD at the same bhp levels.
Last edited by wolfhedge; Nov 9, 2014 at 07:08 AM.
Next came the best mod IMHO, fueling, more fuel, MOAR POWER = giggity.
Tim installed a wallbro intank E85, 400 series FP, Injector Dynamics ID1000s, 6 fuel line, filter and fittings, 6 check valves etc and some new 997 Turbo coils and F5DPOR spark plugs
So with the new set up we did some 60-130 mph runs and got some nice times. This was using 3rd-4th gear rather than just 4th gear but overall my times with either are within 0.1s usually. So this is a good representation of the 1st run with the new tune and RWD with extra fueling. 7.8 seconds or adjusting for slope just under 8.0s, but this day temps were 95F on my test track.
Last edited by wolfhedge; Oct 30, 2014 at 08:41 AM.
Dzenno@PTF recommended looking at power shifting 3rd-4th and as we progressed I used that more and more to improve 60-130 mph times, also the car seemed to adjust to the new tune by Tim and Eurodyne. We further tweaked the tune and started getting this
These runs were all done in 85F-95F temps out here in the Riverhead valley where for some reason it reaches temps 10F higher than anywhere else around.
Last edited by wolfhedge; Oct 30, 2014 at 09:37 AM.
My 4th gear pulls were all now consistently 7.3 seconds to 7.8 seconds depending on slope and weather so about 0.2s slower at these power levels than the 3rd-4th with power shift.
I then cracked off some low 7.25s and 7.219 secs best official in 85F-92F temps on the -2% slope and the car consistently sat at those times all being equal.
I did find a larger slope and got a 6.989 second 60-130 mph but the vbox said unofficial because the slope was -3.19% but temps were 92F that day.
Then I had MAF problems intermittently throwing the usual codes and finally my mate borrowed my car as I borrowed his Macca 12C for a race one day and he red-lined her to the limit one too many times and we popped the MAF sensor. I ordered another from a guy here at 6speed but alas the car hated that one too. Oh well back to Tims for the treatment.
I should note my fuel system IDC% was in the low 40% range at maximum on this new pro tune by Tim.
Last edited by wolfhedge; Nov 9, 2014 at 07:11 AM.
Took the black beast back to Tim's where he awaited with a pile of other Porkers including his red beast which he was readying for Texas. Despite all of his other business commitments and Texas pressures he fitted my car with a MAFLESS set up, filters off the turbos, changed out the oils and filters etc and then topped it off with the MASTERPIECE his E85 pro-tune.
The car is crazy quick now and I may need a new clutch and it now has IDC% near 100% (joys of E85) so it is all a now larger slippery slope into modification addiction.
The tires break loose in 2nd and sometimes 3rd so we will be upgrading those as well very shortly.
We cracked off some stellar 60-130 mph times = 6.76 seconds one after another. I did get one 6.55s but once again that is unofficial because some satellite problems (the dog ate my homework excuse yada yada yada).
I did one 60-130 in 4th gear only and the others in 3rd-4th gear and get identical times almost, epic stuff and 4th gear now pulls like a Moose out for a ****.
I have also tested 60-100 mph 3rd gear only pulls with every mod and the best is 2.68s on E85, 3.18s before MAFLESS and E85 and 3.45 s best before the upgraded fuel system and 3.6 s or so on the old GIAC tune. 4th gear pulls 60-100 mph are now faster than what I ever did in 3rd gear before. Average longitudinal g force is up 0.1.
Last edited by wolfhedge; Nov 9, 2014 at 07:12 AM.
So we now have a car with almost FBO except stock K24 turbos, stock DVs, stock WGs, stock plenum, AWE race exhaust, E85 Eurodyne protuning by Tim941NYC, upgraded fuel system, MAFLESS doing sub 7 second 60-130 mph all the time. RWD and curb weight with me and a full tank of gas approx = 3365 lbs (I am 190 lbs). Car has some LW pieces like an AWE carbon fibre wing, no spare, no tools, LW wheels by BBS etc.
Measured bhp using vbox is now 700-750 bhp depending on day, speed etc or around 600-630 rwhp. Tim was also conservative with the timing and says he could add in even more but the car is a bit of a handful for now so we will keep it here and learn as we go along.
So to summarize all using adjusted slope and temps for DAs etc and each mod we get the following
Last edited by wolfhedge; Nov 9, 2014 at 07:14 AM.
I only used a dyno once when we broke the car... but for the most part I like dynos ONLY as a tuning tool, they are too easily effed with to manipulate a one off good whp nos by whoever is using them. Then they take their messed with whp numbers and add in some fictitious % to convert it to bhp. Post some vbox runs and I will tell you where you are at on a real world run. It is absolutely correct save for scaling errors from GPS/Satellite sampling rates but across 10 or so measures is spot on (100% ***** on accurate to quote My Cousin Vinny).
Using vbox you get PRECISE mathematically correct (engineering and physics-wise) brake horsepower readings. The vbox gives Longitudinal G ratings and so knowing your curb weight and the mph at that G level you can get the exact BHP figure. Do this on a few dozen runs like I do and you get very precient real world, real time data across many runs in many temperatures etc.
Using vbox you get PRECISE mathematically correct (engineering and physics-wise) brake horsepower readings. The vbox gives Longitudinal G ratings and so knowing your curb weight and the mph at that G level you can get the exact BHP figure. Do this on a few dozen runs like I do and you get very precient real world, real time data across many runs in many temperatures etc.
I would think there are other factors in place that will effect acceleration and make horsepower difficult to measure in road conditions.
I don't see any mention of it, are you still running an open rear diff? Although, I think it 2005 an LSD may have been an option. Does yours have one?
Sorry, it has an open diff. AT these whp numbers I can feel the lack of an LSD much more even though it corners well.
I think now that I have finished my little engineering tests on K24s and other bolt on mods I will add the LSD, larger injectors and probably 68mm HTA Forced Performance K24.
Maybe next winter get Tim to up the rods with Carillo, headstuds, larger GT35 or PT6466 turbos (if I havent added K24 68mms by then), but then it will mean a GT2RS tranny, yet another clutch etc... what a slippery slope. It may actually need a rod upgrade if I even just add the K24 68mm HTAs on E85 as we are getting close to the dangerous torque numbers even though Tim tuned it down a bit and we can mess with it more in the Eurodyne.
In reality the car is a little fiery for me now because of tires and 2nd gear going so quickly so I will drive it as is and get used to this new power. I have a pro-racing mate who is going to take me out this winter down in FL in a modded 650 rwhp GT2RS and show me some tricks. I usually drive very much within the car's and my ability except when I am WOT on the empty estate road.
I only used a dyno once when we broke the car... but for the most part I like dynos ONLY as a tuning tool, they are too easily effed with to manipulate a one off good whp nos by whoever is using them. Then they take their messed with whp numbers and add in some fictitious % to convert it to bhp. Post some vbox runs and I will tell you where you are aton a rela world run
Using vbox you get PRECISE mathematically correct (engineering and physics-wise) brake horsepower readings. The vbox gives Longitudinal G ratings and so knowing your curb weight and the mph at that G level you can get the exact BHP figure. Do this on a few dozen runs like I do and you get very precient real world, real time data across many runs in many temperatures etc.
Not looking for max power, although I disagree. My car has dyno'd on an inground dynojet from Georgia in Georgia and a portable dynojet from California in Ga in the same week, same conditions, same correction factor within 4 whp, and one was heat soaked right off the track, sat running for 20 minutes with no fans. It has also within the last 8 years always dyno'd within 4-5 hp on different dyno's. Repeatable results are what matters to me, what that means as far as speed is completely debatable though and doesn't really matter (to me).
What I look for is more detail, how much does hp fall off as car heats up. How quick are you reaching power, how is power holding to redline, how steep the torque/hp curves are. As a road racer I have to look at much more than that as 60-130 is only a few seconds out of a lap for me.
