sergiomartins

Its the first dyno that ive done.
The car has a fully rebuilt engine with less than 8000 miles on it.
The mechanic reckons that the variocam solenoid (that rattles sometimes) is erratic and not working correctly.
Compression is very healty and no codes whatsoever on the DME.
Heres a list of the mods:

RS Barn Performance Head Stage 1
RS Barn Performance Cat Back
RS BARN Custom Performance Chip Stage 1
968 Engineering Airbox Modification w Trim Rings
K&N Air Filter
NGK Iridium Spark Plugs
ETC


Please helpme understanding why??

968workaholic

The fact that the torque number drops in the middle suggests that there is a problem with your vario-cam unit. You could jump it with a 12V power source at around 2.5k and then disconnect it around 5K and see if that changes the graph for the better. If not then something is wrong with the unit itself, but if the graph shows improvement then there is a problem with the signal going to the unit. What did you use to check codes on the DME?

Damian in NJ

It looks like you have a lot of expensive mods (minus, of course, the Dave G airbox mod) that aren't doing anything for you.

SpeedBump

You have nothing to compare it to so how do you know you are missing HP?
Has this person ever dyno'd a 968 before? Any stock numbers to compare it to?

You are missing the top 1000 RPM or so of the engine somewhere which would be more of a concern to me.

968norway

It could be the MAF. I had a similar problem, flat after 5000 rpm. CRC has a MAF cleaner.

Miles968

I am not sure if they are that far off? With the converted numbers can anyone else comment?
127kw=170 hp
289Nm=213 ft/pd torque
160kw=214 hp
I could be completely wrong but I thought more people might be able to understand/interpret the numbers better in their converted form

link to easy converion: http://www.mr2ownersclub.com/converter.htm

Mark944na86

The K&N air filter and iridium plugs are both likely going to result in small but measurable performance loss. I'd return to copper plugs and stock airbox/filter for starters.

AZ968Cab

Why a power-loss with iridium?

Mark944na86

Like platinum plugs, you get longer life but with a small trade-off in performance compared to copper.

sergiomartins

this dyno pull was the best of 4 runs and on premium fuel.
do you think that the theory of the solenoid not activating sticks? it could explain why the numbers are low, maybe like an 944 s2...?
from what i understand 160 Kw is corrected at the flywheel, not at the wheels. ( am i wrong?)
cheers

968workaholic

It should be run up to fuel cut-off to see what the motor will really do. A dirty MAF is a possibility that may be worth looking into, it certainly can't hurt to clean it. The load that the dyno is putting on the car is fairly high at 33kW, thats almost into mustang dyno load numbers. Is there another stock 968 that has been run on that dyno, or any others that you know of that have the same wheel drag of 33kW? There may be nothing wrong with your car, it is just that the dyno is putting so much load on the motor that the numbers aren't as high.

Mark944na86 A K&N will not lose power because it flows better than a paper filter, and the air box mod has worked very well on every car it has been done to. Also, Iridium plugs have so many advantages over copper plugs that would contribute to better performance. http://www.densoiridium.com/spconstruction.php

Mark944na86

Well, there's marketing, and there's dyno results. The S2 and 968 stock airbox is a very good design, and all dyno tests I've seen where a K&N has been used to replace the stock filter on an S2 has shown a small power loss. I'd be surprised if it was any different on a 968.

Same for platinum and iridium plugs -- marketing claims are one thing, dyno results are another.

As for the air box mod, who knows unless it's actually been dynoed? I haven't seen a test result for this. But I wouldn't be surprised if it's similar to installing a K&N.

What I'm saying isn't particularly controversial -- search yields lots of info on this.

nick_968

The first thing I would notice is that your max power rpm is too low. Your car will make max power well into the late 6k rpms and your max power is taken at 5580 rpm. You may also have a problem with the variocam or MAF which might account for the dip in power around 3k. It is hard to make accurate comparisons without a control graph from a standard and known fault free 968 on the same dyno. Your peak torque occurs a little later than factory, but that would make sense if you have a stage 1 head which will probably move the torque along a bit and give a bit more top end power. What is the reason for the car not being taken up to 7k rpm for max power?

RajDatta

With no baseline tests, you don't have a prayer. It's too easy to point in 20,000 different directions now. Was there a problem with your car before? or are the mods not working as advertised? It's hard to tell without a baseline test.
Raj

Fox944

it has been, by several people. The Airbox Mod W/ K&N filter is proven to add HP. Its one of the first things i did to my 968 when i bought it.