3.6 V-ram DynoJet Results

[Mike Feinstein]

I thought this thing was fast, but had to confirm it on the Dyno. If someone can explain how to compress .tif files I'll post the actual charts. Anyway, here's the results:

268.1 rwhp at 6400 rpm
245.7 torque at 4800 rpm

Crank HP calculated as 268.1 / .85 = 315.4!

The thing that's great is that the torque value is above 200 from 3100 rpm until beyond redline.

Only concern is A/F ratio. It goes as high as 15.9 (at 2k under WOT) and gradually declines to about 13.3 at 6800. It is a linear decline and the Dyno tech felt that it was too lean overall. For example, at 5000 rpm at WOT it's at about 14.2.

Car has a Cyntex Vram chip, stock HE's with custom free flow exhaust, Cone filter. Why would Cyntex set the chip up so lean? He said that optimal AF for a performance tuned car should stay flat at around 13.

Spent about 30 minutes trying to compress these scanned charts...no luck.

[Jack Olsen]

That's amazing.

Email me the charts, and I'll do the compressing.

jackolsen@comcast.net

[350HP930]

For a second I thought your post said E-Ram . . .

[Mike Feinstein]

Thanks Jack....just took a digital photo of the chart (low -tech compression).

Here it is:

[Mike Feinstein]

Here's a chart comparing my car to another 993 that was tuned with a Unichip piggyback system. Note his AF ratio remains at 13 all the way up (although his HP is a bit lower than mine ).

[Jack Olsen]

You might want to try running the car on a different shop's dyno before you put a lot of work into solving the air/fuel ratio problem. The numbers you got are great (and I hope they're accurate), but they're also about 30 hp higher than you'd expect for that setup, aren't they?

Has anything else been done to the motor that would explain it?

[Embs]

Mike,

I hope the data is correct, I don't think it is off by much if any. That's weird about the Cyntex and potential lean condition, it doesn't sound right. I tried two different Cyntex chips and both caused the engine to run very rich with no other changes.


According to the manual you can't adjust the CO on these engines, it is all the job of the O2 sensor.


Are you running the single pulley conversion or stock pulley set-up? What wheels & tires are you currently running?

[scca_ita]

I think the 15% drive train loss is a little far fetched when relating it to higher horse power motors. I would say the combined effect of the loss is more like 20 - 25hp from trans, axles and wheels etc.

I have seen dyno figures from 95 motors with headers, more fuel pressure and chip have 267RWHP. So I would say your right on with these figures but not 315 corrected.

[Mike Feinstein]

Jack,
Good advice on the re-check. I e-mailed Steve Timmins about the AF ratio to see what he has to say. I guess I could check with the Cyntex people too (if I can find them).

Todd,
Running single pulley conversion and 7 and 9" Fuchs with B'stone RE-730's. No AC. Same wheels with Khumo Victoracers for DE.

scca_ita,
Your assertion about driveline loss makes a lot of sense. Using a straight 25hp loss would put me at 293 at the crank. The stock 993 motor is rated at 282. With a chip, cone filter, freeflow exhaust, single pulley, no AC, etc., I would hope I'd get an extra 11 hp.

[Early_S_Man]

Guys,

Back in the days of Holley carbs to get max power out of a V-8 ... 12 - 12.5:1 used to be the target A/F ratio to get max power under acceleration! Of course, that was in the days of long-duration, high-overlap cams and 12.5:1 compression ratios, and part of the rich mixture was lost to exhaust scavenging and dilution by burnt combustion products. Avoiding detonation on 100-octane pump gas was also a consideration!

So, that 13:1 may not be far off, from a max power standpoint ... with 11.3:1 compression ratio, detonation is still an issue! Sounds like the DME is running in default rich mode.

[scca_ita]

Most engines make there best power on the lean side. But the risk here is knocking and the DME retarding the ignition which will loose power. So something less than 14 with the correct gas sounds like a good starting point.

[Jack Olsen]

I was comparing the numbers to Timmins' site, where he needed to go to straight pipes to get a dyno number over 300. But I'm not an expert in this, by a long shot.

The 15% rule is something that everyone knows is wrong, but I think the situation gets worse when you have everyone coming up with their own system. How can you compare anything, at that point?

Of course, rear-wheel numbers are the simplest way, but we'd have to come up with some accepted rear-wheel baselines for the motors in stock form, and work from that.

In any case, it sounds like the motor is putting out great power, with the only scary thing being if the lean condition is actually there.

[Speedster94]

hallo
The Stock number is 286 HP on the Euro varioram , also there is a 5%
up/Down HP from the Factory . If you are lucky you have 299 HP with a Chip you can get very easy 10-15 HP . I think this numbers can be correct . Happy new Year to all :
harald

[Mike Feinstein]

Harald,

Any comment on the AF Ratio curve?

[pjv911]

Power at the rear wheels is all that matters. Unless your putting a propeler on the motor and going flying who cares what the crankshaft power output is . 268 rwhp is very impressive mike. By comparison my old 2.7 put out only 156 rwhp and that felt nice. Did you run any 0-60 numbers yet ? How about 30-70mph ? Those are the #`s that we can easily relate too.

Kurt Williams

[Speedster94]

i guess that the Chip is not adjusting the Fuel to the Airmass-Change of Varioram-opening .Check the Color of your Sparkplugs ,as long as they are not silver/white insted of light/brown the Ratio is not too bad .
Did you bring your Car to a Dyno and they made the Chip after reading the Data from YOUR Engine ,or did it come in the Mail ( one size fits all )
? harald

[pjv911]

On my dyno I normally shoot for 12.0 to 12:50(at wot). Most all of my dyno pulls are on turbocharged cars. BTW are you using oxygenated winter fuel ? Here in New York thats what you get at the pumps until spring time. That will directly affect the O2 readings on the dyno`s exhaust analyzer giving you those readings.
Also make absolute sure that no uncalibrated air is coming into the engine(all intake air must pass through the mass air meter). Check your idle valve for this. Does the engine run and respond just as it would if still in the 993 it came from ? Chances are you have nothing wrong with your a/f ratio. But its worth looking into and you could possibly find a few more ponies in that torque monster.

Kurt Williams

[911pcars]

Mike,
I wouldn't take any dyno numbers as the absolute gospel truth. These are only good to impress folks on bulletin boards. Use the numbers as a reference point for any subsequent tuning. Your goal should be to optimize the A/F ratio and spark advance so it produces max. torque and HP across the rpm range without detonation and overheating. Is it too rich or too lean? I'd suggest installing a EGT gauge to monitor the combustion temps while experimenting with various A/F ratios. Once you arrive at the right combination, you can go out and play with relative engine security.

Sherwood
http://members.rennlist.org/911pcars

[Mike Feinstein]

Kurt and Sherwood...no 0-60 or 30-70 times. Not that concerned about these times...mostly I just wanted a baseline HP and torque value for future comparisons and to verify V-ram actuation. Used plain old 93 octane Chevron no-lead (no winter blends here in the South). Cleaned ICV a few weeks ago and all seems to operate fine. Also, my 89 weighs in at about 2840 lbs...much heavier than your old 2.7 I'll bet.

Harald...chip is a "custom" chip by Cyntex Performance Tuning and it is made for this motor....but no, it was not programmed on or for my specific car. I plan to call Cyntex on Monday to ask about these results.

[BlkBird]

Mike,

Damn you are setting the bar pretty high. Now I have to worry that you have more HP and the bragging rights that go with it. Knew the car was fast but these are pretty impressive figures.

You should stop now. You don't need more HP. You should be satisfied and stop making the rest of us feel insignificant.