3.6 Vram conversion impressions, dyno results, and video

[MuffinMan]

With a twist of the key, the "whir whir whir" of the high-torque starter brings the 1997 3.6 Varioram engine to life. The exhaust note from the factory 993 heat exchangers and Triad muffler is quite nice. It has a pleasant rumble at idle while not being obnoxious, and it sings very nicely up to redline. I previously had a stock 2.7 in the car that dyno'd at 115rwhp just before removal. The car is truly transformed with the rebuilt gearbox and more powerful engine, to say the least. There is so much torque on tap at lower rpms that it simply begs you to squeeze on more throttle to unleash the beast within.

Without going into detail, I'm extremely happy with the final result. The installation was extremely professional and clean, and the decisions I made during the process all turned out to be sound. I never needed a limited slip as much as I do in this car, it's the low-end torque that wants to break the rear tires lose at slower speeds or when merging into traffic on a cold day. Fun.

Nevertheless, I organized a dyno day that was held last Saturday. It included a weigh-in and several runs on a Dynapack dynamometer. The dyno mounts directly to the hubs, and yields repeatable and consistent results. Seven cars in total were there, so it was nice to be able to benchmark your car to others. We videotaped all of the runs and one of the guys made a nice compilation. There's only one run of my car on there, and video does not convey the beautiful scream to redline for any of the cars. It's far more impressive in real life for all of the cars tested...perhaps except for the 914 2.0

All of the digital photos are on my home computer, so I will have to post them tonight, but I'll add a link to the video for now. I'll also post the dyno charts for the 3.6, and sometime next week I can post the dyno charts of the 2.7 plotted against the 3.6. The charts are all displaying rear wheel hp, not "corrected" flywheel hp. I also wrote a large article on the day, but it won't be posted on the GTC Motorsports website for another week or possibly published in Porscheforus for a couple of months (club newsletter).

In case you didn't follow my previous thread that listed my setup, this is a 1997 US 3.6 Varioram engine with a modified computer from Rennsport Systems. The factory airbox is cut open to simulate the cup airbox, and I used factory 993 heat exchangers with a Triad muffler and no cats. I was very concerned about choosing the right combination of chip & exhaust during my conversion, since there were no dyno results with the Rennsport programming or the Triad exhaust, so I hope this helps a future 3.6 converter out.

As far as the video, there are 7 cars shown. They are as follows:

1974(?) 914 2.0
1978 911SC euro w/ stroked 3.0
1976 914 w/ high compression & twin plugged 3.2
1997 993S (GHL mufflers, otherwise stock)
1995 993 (unknown aftermarket mufflers, unknown chip if any)
1977 911S w/ 3.6 varioram
1994 911 3.6 Turbo (apparently, NOT stock)



The peak was 252.9rwhp at 6526rpm. I had three runs, and all of them were almost identical, unfortunately, the operator didn't bump the car quite up to the 6700rpm redline, so there are a few ponies unaccounted for. Here are the results:

[Jack Olsen]

Cool! I think you now have the right to start your own OBDII World Domination Plot.

Does Steve do any tweaking to the timing/fuel maps in the process of disabling the OBDII obstacles?

I feel a little sorry for the 3.2 guys who swap in a 3.6. They get a power and torque bump, but it's not as dramatic as what you saw. With my car, I went from a 2.2T motor with about 125 crank hp, so the first ride with the 3.6 was eye-opening.

[MuffinMan]

As far as my plan for OBDII world domination, I think the government has already begun the process for me . At least I have a snazzy little diagnostic port to play with.

Steve Weiner reads this board occassionally and I'm sure he'd be happy to give you the details, but he does modify the mapping. One thing I noticed in my chart was that the a/f ratio was very flat at about 13.0, while the 3.6s with stock chips had curves that became richer as the rpms increased.

I'll post a copy of the 97 993S's dyno chart below. It read lower than expected, so we checked it with the System Tester II after the run. There was a code for a bad oxygen sensor and/or bad mass airflow sensor. Fixing that problem should put him closer to stock power. Nevertheless, here is his chart:

[Jack Olsen]

I know it's a losing game to compare dyno readings from different machines, but your torque numbers are lower than I'd expect.

My car has lower hp numbers, but more torque?




Then again, D Hanson's 3.6 torque numbers were even higher:

Rear wheel torque peaked at 239.9 ft/lbs at about 4,800 rpms but was over 200 at 3,600 rpms and I had 215 ft/lbs by 3,900 rpms. Torque went to 235 + and stayed there for 1,000 rpms until it dropped below 200 lbs at about 5,800 rpms.

(His rwhp number was 245.9)

[Bill Verburg]

Rob, Great job!, Makes me even sorrier that I couldn't make it!

[MuffinMan]

Originally posted by JackOlsen
I know it's a losing game to compare dyno readings from different machines, but your torque numbers are lower than I'd expect.

My car has lower hp numbers, but more torque?

I believe my muffler may be robbing me of torque, but I'm happy enough with the sound that I'm not going to hunt down the missing power by experimenting with different systems.

[Craig 930 RS]

Excellent! I can only hope my Varioram experience is as rewarding.

Cheers!

Craig
RS
Varioram just arrived

[Steve@Rennsport]

If I can just chime in a moment here,....

Jack:

Indeed, I do alter fuel & timing maps quite a bit and I have a bit more liberty when doing a car without cats; hence the nice even A/F curve. The whole goal is not necessarily searching for peak HP; the "chip" exercise is all about finding best torque, the widest powerband, and best drivability & throttle response.

As you already know, the main goal is to enhance acceleration,...

Lastly, muffler choices and exhaust tract length/diameters make a HUGE HUGE difference in the quantity and shape of the torque curve. After 30 years of dynoing these things, I've yet to find an exception. Its all too easy to ruin the bottom end torque on these things and make a torque plot look like a roller coaster,...

One learns by experimenting on the dyno and I still learn new stuff every day.

[1fastredsc]

Hey muffin, tell mike and keith that slaveboy says high for me

[dwightp]

Steve:

All sooooo true! Thanks for reminding us and keeping us on track.

dwight

[MuffinMan]

Here is my stock 2.7 vs the 3.6.

[Rouxzy]

Now you're getting me really excited. If everything goes right my 2.7 is coming out and a 3.6 will be in by May or June. What did you do for your tranny? Did you need to do anything to help with the extra torque?
Tom

[Bill Verburg]

Thats a great comparison!

Just for the heck of it here is the factory chart for a 993RS

[MuffinMan]

Originally posted by Rouxzy
Now you're getting me really excited. If everything goes right my 2.7 is coming out and a 3.6 will be in by May or June. What did you do for your tranny? Did you need to do anything to help with the extra torque?
Tom

I rebuilt the 915 (late magnesium case) and added a GT LSD.


Bill, that torque curve is so sweet

[Bill Verburg]

I love the Dynapack measurements. You can see the family resemblance in the torque curves. That tells me that the Dynapack is probably measuring the same thing as the factory.

[AES]

I notice that the chart for the 77/993 and 993 both show the same gear ratio. how can that be? Am I missing something in thinking that the gear ratio affects the output at the wheels?

[Embs]

Rob,

I wonder what the Triad +/- is doing to your numbers?
I love the sound and fit, but I wonder what the difference is with other options.


Within the next month I am going to dyno mine with the 993 HE's and a 993 cat only, then with the 993 HE's and the Triad.


I will post the results and hopefully some audio/video.


I suspect you have 10 to 15 additional ponies that didn't get accounted for!!

[MuffinMan]

Originally posted by AES
I notice that the chart for the 77/993 and 993 both show the same gear ratio. how can that be? Am I missing something in thinking that the gear ratio affects the output at the wheels?

Both engines are in the same car with the same transmission. The charts demonstrate a before/after for a 3.6 conversion.

[MuffinMan]

Originally posted by Embs
Rob,

I wonder what the Triad +/- is doing to your numbers?
I love the sound and fit, but I wonder what the difference is with other options.


Within the next month I am going to dyno mine with the 993 HE's and a 993 cat only, then with the 993 HE's and the Triad.


I will post the results and hopefully some audio/video.


I suspect you have 10 to 15 additional ponies that didn't get accounted for!!

I have the exact same question. I suspect the Triad, while sounding very pleasing to the ears, isn't doing much for the power curve. Fortunately, we will have real world data once you complete your dyno! Dave@Triad told me he was going to do the exact same dyno test you're referring to, but he never got back to me with the results. Nevertheless, I still have the factory cat sitting in my garage, so swapping it on is an easy alternative for me. I'm anxious to see your results!

[AES]

Both engines are in the same car with the same transmission. The charts demonstrate a before/after for a 3.6 conversion.

No I understand that the 2.7 vs 3.6 was in one car but isn't this one



In a 993 showing the same gearing as yours?