haygeebaby

Guys
Dyno'd the car today and was really dissapointed. Took the car to a nice garage called The House of Power in WA and dyno'd on a Dyno Dynamics dyno. We did three runs, all in 3rd gear.

My car is a 94 C2 with 911chips chip running 98RON, Cat Bypass, BMC airfilter, drilled air box, and RS pulley installed.

These are the figures I got:
205rwhp @ 5,700rpm (account for 20% loss = 246bhp)
255lbft @ 4,400rpm flywheel torque

Stock figures are:
272bhp @ 6,100
243lbft @5,000

So looks like the torque is ok - figure is slightly above stock and the curve is pretty flat all the way through the rpm range.

Air Fuel Ratio - according to the dyno guy - is good - It ranged from 13.2:1 @ 3,550rpm to 12.6:1 @6,200rpm. Is it good ?

But the bhp figure is way down - about 30bhp down from stock. With the mods I had I was hoping to get around 290bhp.

What can I do boys ? Need some pro advice for you guys. I'm thinking that I should get the timing checked out, and change the spark splugs.

When I get the soft copy of the graph I'll post it up for you to see.

Thanks in advance ...

bart1

Distributor belt?

tj90

Sometimes ignorance is bliss... Hopefully someone will give you some good advice to improve the numbers.

drmatera

is 3rd gear 1:1 ? if your running in a gear other than 1:1 it will skew the results. Most 5sp trans are 3rd 1.35:1 (roughly) 4th 1:1 and 5th "overdrive". also i put zero importance on dyno results.

Stealth 993

Find out what other 993's do on the dyno. You can't really get engine hp from it, you are just making a guess.

It would be nice if you can post your dyno chart, that has a lot of useful info, & is more important then the absolute numbers.

chris walrod

Using third gear may have scewed your results giving you higher artificially inflated numbers, hate to tell you. 4th gear is typically used to dyno 993's.

Warpig

Dyno numbers can also vary by type of dyno equipment by a good amount. I have seen the same cars on one dyno show numbers with 15-25 hp of a difference on another dyno. You would think they should be the same but often they are not. Also was any report weighting adjustments used SAE/STD/NET? I agree you need to compare with other 993's on that same dyno, preferaby on the same day, there are many variables.

Try to use the same dyno for a baseline before/after mods is the best way to see if what you are doing matters. The overall numbers, not so much just that you are heading in the right direction in reasonable increments.

Nick

RollingArt

[QUOTE=haygeebaby;6629028]Guys
Dyno'd the car today and was really dissapointed. Took the car to a nice garage called The House of Power in WA and dyno'd on a Dyno Dynamics dyno. We did three runs, all in 3rd gear.

My car is a 94 C2 with 911chips chip running 98RON, Cat Bypass, BMC airfilter, drilled air box, and RS pulley installed.

These are the figures I got:
205rwhp @ 5,700rpm (account for 20% loss = 246bhp)
255lbft @ 4,400rpm flywheel torque

Stock figures are:
272bhp @ 6,100
243lbft @5,000

But the bhp figure is way down - about 30bhp down from stock. With the mods I had I was hoping to get around 290bhp.




272bhp -20% = 217.5

That's a diff of only 12.5 bhp. to what you dyno'd at.
That much could be attributed to a difference in the dynos used to obtain said results.
I wouldn't sweat it so much. If the car feels strong just enjoy it.
You can use these numbers as a baseline for future mods and dyno runs. (on the same dyno)
You also could have possibly lost power if you were running it on higher than the recommended octane. I'm not sure where 98 RON fits in. But if your car is tuned to run pump gas, and then you try to run high octane fuel, the combustion process will be slowed to the point that you'll lose some power.


Phil

TomF

I don't know about the 911chip, but Steve Weiner can tell you that many chips will actually do more harm than good. Post your chart and maybe some wise guru here can give you suggestions. I would try to put the factory chip back in and see if it feels better.

chris walrod

This was actually my first thought, but thought to mention being in a gear with a ratio as close to 1:1 as possible.

Arent typical transaxle losses 15%?

Steve Weiner-Rennsport Systems

As others has wisely said, one cannot compare the results from one brand of dyno to another. Such figures are only useful when compared to itself so one can evaluate any changes or modifications. Further, dyno runs MUST be performed in the gear closest to 1:1 to get anything reasonable to look at,...

I can tell you that you'll not see anything remotely close to 290 BHP with the mods you have done thus far, based on extensive engine dyno development with these cars.

Matt Lane

Hi Steve, just curious since my butt-dyno tells me I've lost a bit of power since I installed Supercups... but was wondering: in terms of your dyno experience with gains/losses from common mods, can you provide an indication of (cumulative) power to be gained from basic NA induction, exhaust, and chip modifications to a an otherwise stock vram 3.6? Basically, short of rebuilding to higher specs.

An in your experience, will a low mileage and properly maintained 993 dyno at, below or above the rated HP and TQ figures?


Thanks as always for your great support!

Steve Weiner-Rennsport Systems

Hi Matt,

Personally, I'm not a fan of the Fabspeed Supercups and cat bypasses since I've observed significant losses of low & mid-range torque which is counterintuitive for best acceleration.
I'd rather have the 15-20 lbs-ft than the 20 lb loss,.....

Now,....we do use such things on race cars when close-ratio gears are employed that keep the engine RPM in its best power producing range along with RS cams (or better) to extend the useful RPM range of the engine. Properly done, this can offset the loss of low-end power for track cars.

For a non-Varioram car, this isn't something I'd do for street usage.

Unless you are willing to do some internal engine modifications such as RS cams and RS intake valves, I'd stick with good software, OEM or GOOD sport cats, mufflers of choice and your drilled airbox cover. I would also recommend having someone competent check your cam triming as we've found a lot of these engines that are at the edge of spec and that REALLY affects how they run. When one cam is at one end of the specified setting and the other one is at the opposite end of the spec, it will not make rated power.

I can tell you that a 3.6 with RS cams, intake valves, and good software, can make 300 HP,.....more with a race-type exhaust (not street legal).

haygeebaby

Yeah - im starting to wise up with dyno runs after all the comments - cheers guys.
When I check the ratio for a 4-speed tip, the 3rd gear ratio is 1.000:1. 4th gear is 0.728:1. So running a tip on a dyno on 3rd gear is correct ! Right ?

Manuals - should be done is 4th I take it ? But 5th gear is closer to 1:1 - i.e. in G50/21 and above the ratio is 1.027:1 - and 4th in that gear transmission is 1.242:1. Even in the G64/21 - the 5th gear ratio is 1.024:1 where 4th is 1.242:1. So is 5th better for a manual dyno run considering 1:1 is best ?

The car runs well and does pull strong. My friend who dyno'd at the same time, with a BMW 335i E92 dyno'd at 285rwhp. That's a lot more bhp, but when we are at high speed (100km's plus to 220km's) the 335i is only pulling ahead ever so slightly.

I think I will get the timing checked. And take the cat bypass and BMC out - and will run another dyno - since I have a base line figure now.

What about spark plugs and checking vacuum leak ? Anyone have expereince with this ? Or any other problems I could check for.

Yeah - getting bhp out of these cars is expensive - RS cams and intake valves. Oh man - I think the slope is getting slippery again.

More comments please - really welcome them. And soft copy of chart is coming.

Regards

chris walrod

Yes. Now knowing you have a tip, third gear is appropriate.

So, this is good news since you may after all have a good baseline. Just kinda have to continue using this particular dyno with hopefully similar atmospheric conditions.