Another Acceleration Test

Lawrence Coppari · 12-29-2002, 07:11 AM

Finally got around to testing my car with the track tires on it - well on the rear anyway. They are 245/45-16 in size. Here are the times from 70-100 in 3rd gear at full boost. The temperature was 38 F with 1/4 tank of fuel. I was in the car alone. I weigh 150 lbs.

Two runs were made in opposite directions to compensate for any slope in the pavement.

Run 1 3.59 sec
Run 2 3.66 sec
Average time 3.63 seconds

With the 225/60-16 tires that give correct speed, the time is 4.15 seconds. That was done last winter at 50 F with 1/4 tank fuel.

1.2gees · 1.2gees's Garage

Not bad, I'm still much closer to 4 secs (I think avaraging 3.9 at this point). Next week I'll be trying a different set of chips that I'm hoping will make somewhat of a difference, fix my exaust and boost leaks and give it another try before the temps start getting above 50 degrees! Oh and before I forget, VIR anytime soon Lawrence? If I can get enough money together I will be going sometime next month...
Ahmet

Lawrence Coppari · 12-29-2002, 07:39 AM

I am thinking about going to VIR on the 15-16 February. I have no experience at that track. Most of my track stuff for the past few years is at Road Atlanta.

CJFusco · CJFusco's Garage

good times! what does it run 1/4 mile?

Lawrence Coppari · 12-30-2002, 05:09 AM

I don't do any acceleration tests that require me to start from zero. In fact I don't floor it in first. I'd like to but I don't want to purchase a new tranny.

I have another vehicle that was tested in Car and Driver. It did a 13.0 second 1/4 mile. It takes 4.74 sec to accelerate from 70-100. My 944 with the big tires that give correct speed gives a time of 4.15 seconds. So I conclude my 1/4 mile times would be in the mid 12's. My turbo is fast but I have encountered faster ones - alot faster.

Dougster · 12-30-2002, 07:58 AM

What do you think your Turbo rates HP wise Lawrence? & what mods? Mid 12's is pretty quick! Sounds like you have a strong runner!

Lawrence Coppari · 12-30-2002, 08:53 AM

Mods:

Higher fuel pressure
K27DR turbo
MAF
Extrude honed intake
Ported/polished head matched to intake
Larger pre/post boost tubes
Reamed throttle body

All of above except reamed throttle body was purchased from PowerHaus.

I have another car that weighs 3265 lbs and has 349 hp at crank. Based on comparing car weights and elapsed times, I estimate I'm getting 370-380 at the crank. This car did 1/4 mile in 13.0 in the C&D testing. Since the 944 is faster, I have to assume somewhere in the 12 secnd range. The mid twelves was just a guess. Maybe high twelves. You're right, the mid twelves might be getting a little carried away.

Car has 138K on it. I have never done a compression test. I did the rod bearings last winter.

ImClueless · 12-30-2002, 02:58 PM

Hey lawrence, how hard is the rod bearing job...

Lawrence Coppari · 02:49 AM

ImClueless,
It took me three weekends but I work far slower than most other people and have a number of vehicles so if one is incapacitated for a month or so, it does not matter. I have a car lift in my basement but younger people have done it without lifts.

The actual changing of the bearings was not hard. I supported the engine from the top with some wooden planks and chains. The most difficult thing was getting the power steering line off near the front of the car. Others have not commented about this but I found it difficult. Putting the pan back on necessitates some technique and everyone has their own method.

Email me if you'd like some pictures I took during the job showing supports and what was off. lcoppari@eastman.com

I also have some step by step instructions you can have if you want. I found them on internet.

1.2gees · 1.2gees's Garage

OK, I must've done over 30 tests last night (was out for a long drive out of town). With just me, and about a half tank of gas the car's running repeatable 3.6-3.7s. Highest time I got was 3.8, lowest was 3.5 (I'm using a mechanical stop watch going only to tenths), also factor in about 0.1 seconds for human error +/-. With a ~170lbs passanger in the car, I'm doing a low of 3.7 and a high of 4.0, all tests done last night, I believe it was around 45-50 degrees. I still have a few minor problems but I don't think they would shave over 0.1 secs from the time.

This is running guru chips, relia-boost set to 15lbs (but will go to about 16 in third), 3 inch open exaust with one open muffler, slight headwork, 3bar fpr, and an intake as well as header wrap.
Ahmet

Lawrence Coppari · 12-31-2002, 10:00 AM

Ahmet, those are good numbers. I'm running 1.1 bar boost. I left that fact off. My muffler is factory which is open. What is your tire size?

1.2gees · 1.2gees's Garage

Thanks, I've got the stock size tires in the rear (as well as front at this point)225/55/16. EDIT-->stock size is 225/50/16, which is what I have, sorry about the typo

After putting in the boost controller, different chips and fpr, it doesn't really seem faster. The stopwatch barely records a difference. I'm somewhat dissapointed w/the preformance of this set-up. Before full throttle off idle would break them loose in first now it doesn't, unless I'm also on the brake, then they frantically spin when passing around 4k. These chips make the car a whole lot more drivable and predictable, which was a big problem I had w/the europroducts chips, I think boost comes in smoother and earlier so I suppose I'm satisfied but I would've liked to see a more quantifiable gain. It seems like the boost controller is working but it will still go to about 20psi in 4th gear rolling on boost from around 3k rpm. I think I need to un-shim the wastegate a little before I put this thing on the dyno, so that it can vent enough pressure to hold the boost down to 16-17 max. I'd also like to add a safety "relief" valve on the intake side set to about 17.5psi, and a second blow-off valve that vents to the atmosphere. Wow, I just found a way to make a long post again...

Happy New year to you btw.

Ahmet

1.2gees · 1.2gees's Garage

Hold on, the 245/45/16s should give the correct speed (they're within .02 in overall diameter as the stock 225/50/16 or 205/55/16s if I remember correctly). 225/60/16s should be making your car slower, from gearing as well as making the speedo read low because they're much taller...?
Ahmet

Lawrence Coppari · 12-31-2002, 02:18 PM

The 225/60-16 tires give 1 minute intervals at exactly 60 mph on iterstates between mile signs. The 225/50-16 tires read a higher speed that is not correct according to my car.

1.2gees · 1.2gees's Garage

But then you end up doing a real 60-100 acceleration test, not "indicated", which is fine but that's not what most of us are going to end up doing...
Ahmet

ae1969 · 12-31-2002, 02:54 PM

Those are some wild numbers....

The only problem with the 70-100 mph runs is that everyone seems to do them differently...... also doing hand timings really are not accurate....

The question I have is that everyone that runs these tests get some incredible numbers. You guys are talking about 944' turbos running 0-100 mph in less than ~9-10 seconds? (Extrapulating from these under 5 second 0-60 times, and ~3.5 second 70-100)... Do you guys know how many cars can do that..... Flip to the back of Car and Driver to get an idea.... I think the GT1 does it in ~ 7.8 (0-100)

I think the 944 turbo can be a monster....but we just don't have enough time slips, or dyno results to back it up (as opposed to the other imports, stangs, F-bodies etc).... excluding Grahams +400RWHP +400Lbft 2.8 liter custom 944 turbo.

You guys have some great setups, but I would love to have a time slip to back all this up so when my buddy comes over with his Stock 99' LS1 slip of 12.73, I can wave the porsche banner!!!!!

1.2gees · 1.2gees's Garage

I have ran several g tech verified 5.0 seconds to 60, stopping timer at around 62 indicated has always been within 1/10th of a sec every time compared to the g-tech reading in my turbo. (passanger says go as he clicks timer, stops @ slightly over 60mph indicated). Nonetheless 0-60 runs with a timer can get ify yes but a 70-100 timed run leaves much less to the accuracy of the timer. Driver floors it at 60, timer clicks once @ 70 once again @ 100. I've timed several race cars with a timer to .1th of a second several times from beside the track, it's not that hard...

I'm pretty convinced my turbo can do 0-100 in slightly under 10 secs, but that's a far cry from 7 and change.
Ahmet

1.2gees · 1.2gees's Garage

I can't vouch for anybody esle but as far as I know Lawrence and I both do the 70-100 runs similarly, as follows:

Cruizing a@60 in 3rd floor it
Start timer @70
Stop timer @100
Back off the gas.

I still think this is the best way to measure a car's on the road performance, much more informative for me than 0-60 or even quartermile times. Too bad there's not more published data to compare to.
Ahmet

Yan · 01-01-2003, 05:28 PM

As seen in this video (0-110 mph acceleration), I accelerated from 70 to 100 mph in about 5.2 seconds.
I'm running on stock chips and at about 14-15 PSI (I guess it's a shimmed wastegate). I shifted in fourth before 100 mph, so there is a 0.1 or 0.2 seconds improvement margin.

Wow guys, you obtained bada$$ times (low 4s or below)!!! I think that I need to order some Guru Racing chips.

1.2gees · 1.2gees's Garage

If anybody's interested you might want to follow the discussion here as well:

http://forums.rennlist.com/forums/ultimatebb.php?ubb=get_topic&f=15&t=014803&p=1

Lawrence I've quoted some of the things you've posted here, hope you don't mind.
Ahmet