Quote :

" again, i doubt its the dyno b/c an un-chipped 1.8t (i think he had a tb exhaust, thats it) put down like 185/185 "

Actually I'd say that right there points to the dyno being screwy. Thats quite a bit more than a stock car with a TB should put to the ground, by at least 10%

1/10/2006 11:53:23 AM

well.. gerich put down almost exactly the same numbers (a while back) as he did at CAM.

1/10/2006 1:53:09 PM

i just spent some time looking at the dynos on vortex, it seems like there are quite a few ppl who only have TB and no chip and putting down ~170-190hp, so im not sure anymore, whether it is correct ...is it dyno or what. i think the hp number is definetly inflated. it should run around 200-205hp. 215hp is easily KO4 territory, or heavily moded Ko3

[Edited on January 10, 2006 at 2:22 PM. Reason : f]

1/10/2006 2:21:13 PM

Those inflated numbers are probably occuring because you ran it in 3rd. A lot of people say it wont make any difference but I don't know that I agree.

1/10/2006 2:33:51 PM

it will change a little... maybe around 10hp. depending on the gear, the hp will go up/down and the torque will go down/up.

1/10/2006 2:36:35 PM

Well, if it's supposed to be 200-205 and he made 215, then that sounds like the cause to me. How did he expect to get results that he could compare to other people's by running it in 3rd?

[Edited on January 10, 2006 at 2:50 PM. Reason : ]

1/10/2006 2:48:35 PM

i think the questionable number is the torque.. seems kinda low...

1/10/2006 3:29:19 PM

saab, few people mention on forums in what gear they ran. there are ppl that ran in 3rd and 4th. ive seen both sides, and so far i havent really seen a consensus whats correct.

[Edited on January 10, 2006 at 3:31 PM. Reason : fsdf]

1/10/2006 3:31:34 PM

3rd for o2m != 3rd for o2j

1/10/2006 3:48:55 PM

^^The gear that is closest to 1:1 is the correct gear to use. If you dyno it in 3rd I think that barring some very strange circumstances you will put down more than in 4th. I'd also say it's likely that 4th is closest to 1:1, unless it's an overdrive (Which I highly doubt is the case). Some cars make more power than others, maybe your car just doesn't make as much torque or something?

[Edited on January 10, 2006 at 4:04 PM. Reason : ]

1/10/2006 3:48:58 PM

4th gear pulls are far more widely used than 3rd.

As for his dyno graph , the whole thing is out of whack. For his mods and motor the HP is higher than it should be, should be more like 190-200, and its arrived at quite a bit higher in the rpm range than would be normal . His torque numbers on the other hand are very low for what would be expected on his car, 220-230.

1/10/2006 4:17:20 PM

If he has an aftermarket ecu it may be holding boost back a bit at lower rpms in 3rd gear to reduce wheelspin or something. At what rpm do these engines normally make peak torque anyways?

As for the whp being too high, I really think the 10-15hp difference between his car and others likely occured from him doing the pulls in 3rd gear.

[Edited on January 10, 2006 at 4:44 PM. Reason : ]

1/10/2006 4:41:40 PM

i really don't see why it would matter what gear you're in at all...nor do I see a reasonable way to approximate which gear is "1:1"...after you factor in tire size and rear end gears there's no telling what it'd actually be (well in a rwd car anyways). force is force...which along with RPM is used to calculate HP. i just don't see how it makes a difference, somebody explain that knows wtf they're talking about if it's truely the case

1/10/2006 7:07:06 PM

I was under the impression that overdrive meant that the gear ratio was over 1:1, thus the highest gear before overdrive would be the closest to 1:1.... I mean correct me if I'm wrong on that. I wasn't factoring in the rear end gears because he doesn't have any!

Quote :

"Different Gears Back in the May, 1998 Technobabble, I dyno tested a Sentra SE-R in every different gear. Second, third and fourth were very similar, but first and fifth were quite a bit lower. Testing a car in either first or fifth is a little odd, and would probably be noticed by the car owner if they were observing the test. The differences are much more significant on a turbocharged car, though, as the higher gears slow the engine's acceleration and allow the turbo to spool up earlier and stronger. If you do a second gear pull with a turbocharged car, the engine will often outrun the turbo--by the time the turbo is spinning fast enough to make boost at 3000 rpm, for example, the engine will already be going 4000 rpm; by the time the turbo is fast enough for 4000, the engine is at 5000."

This came out of SCC. That probably explains why his torque was low and the powerband was shifted to higher rpms. I don't get the hp thing though if this is true.

[Edited on January 10, 2006 at 7:46 PM. Reason : ]

1/10/2006 7:21:13 PM

I know that he doesn't have any rearend gears since he has no rearend....but using your logic, there's no way to properly dyno a RWD car. I'll ask on some other forums and see what kind of answers I can get

I compare it to riding a bike...Your legs have the same power all the time...they just manipulate it differently for either more speed or more force depending on what gear you're in. That doesn't change the output of the 'engine' or your legs in this case. A dyno should take into account this speed/force relationship when calculating its torque numbers...which along with RPM directly correlate to HP. I could be totally wrong, but nothing else would seem very logical or consistent.

[Edited on January 10, 2006 at 7:46 PM. Reason : ^that too, in this case...]

1/10/2006 7:45:45 PM

I mean you're probably right judging by what that article is saying. I guess overdrive makes it loose power though? I dunno, seems odd.

1/10/2006 7:49:26 PM

Quote :

"4th gear pulls are far more widely used than 3rd. As for his dyno graph , the whole thing is out of whack. For his mods and motor the HP is higher than it should be, should be more like 190-200, and its arrived at quite a bit higher in the rpm range than would be normal . His torque numbers on the other hand are very low for what would be expected on his car, 220-230."

yeah.. so b/w 3rd and 4th, hp goes down a little and torque goes up? that would make sense...

1/11/2006 2:20:01 AM

For what it's worth, when I dynoed my car at CAM, I did it in 3rd. This was based on the recommendation of a couple guys who have made good numbers on N/A rotaries. When I went to the dyno, I asked Jeff if he needed to know the 3rd gear ratio b/c it's higher than 1:1 (1.333 I believe). He told me the dyno doesn't need it and can make all the necessary calculations.

So maybe the gear has more to do with whatever the ECU or the turbo might be doing rather than the actual dyno itself.

[Edited on January 11, 2006 at 9:36 AM. Reason : .]

1/11/2006 9:35:37 AM

^ basically what I said...the dyno can/will do the math regardless of what gear you are in

I'm sure its possible for there to be more resistance thru the tranny in certain gears in some cases but I could hardly see that being significant

The turbo spooling time theory though does make sense in this case though.

[Edited on January 11, 2006 at 11:15 AM. Reason : asdf]

1/11/2006 11:14:45 AM

What was the point of this thread again?

1/11/2006 3:32:22 PM

so what exactly is the reasoning behind running it in closest to 1 ratio?

1/11/2006 3:37:07 PM

^ Sounds like it is based in part on a myth that it is more accurate

1/11/2006 3:44:02 PM

The gear the pull is made in can effect the results, but it depends on the type od dyno as to how much.

A dynojet used fixed mass rollers and how quickly the car accelerates them to determine power. Dynapacks bolt to the hub and have to have quite a bit of info put in them to correctly determine power. Same with Mustang and most other types of dynos.

So the different gear will have different effects based onthe type of dyno its run on

1/11/2006 3:59:55 PM

Dern, wrong thread...

1/11/2006 4:48:17 PM

if anyone needs a data logger i have a obd2 pocketlogger with palm and hotsync cables i'll let go for cheap because i have a obd1 car now

1/11/2006 5:06:08 PM