Dyno Inside Kinda

[Ca_Silvia]

Well after a long 2 year road i now have my Silvia to the point i've wanted it for quite sometime. To start:

CA18DET bone stock3 Turbo back exhaustSSAC Down pipeSSAC Exhaust ManifoldPort Matched Intake Manifolds with removed butterfly'sSR Turbo 444cc InjectorsZ32 MAF

I have been running a mail order Dr Drift EPROM tuned for my setup, while its definatly not perfect its a decent baseline to build from. My Tuner i took it to locally is Wyn at Autodream here in Calgary. While he wasn't able to trace the chip in order to modify it, he ordered a new program that could so he can custom tailor a map to suit my motor.

3rd gear pull 180.5whp on a dynojet. Nothing out of this world but as i said a decent base line to start with. AFR show on the graph @ 12.5 but we upped the fuel pressure since and its now running 11.8 AFR. My tuner said my actual whp is probably a little closer to 200 because you are suppose to do pulls in 4th, is that true about the power increasing or is he just selling bigger numbers?

Photobucket is ghey and for some reason wont let me upload a pdf so no graph yet. So if anyone can help me along those line im sure it would make this thread alot more interesting.

[bradt]

I thought pulls were supposed to be third gear....

[progman]

You can do a pull in any gear you want. If you car is very powerful you might want to do it in your highest gear so you have better resolution on your data logging. But the reason he said there would be more power in forth gear is because in our transmissions forth gear is the 1:1 gear and the transmission takes up less power like this because there is less mass to spin around in there. I'm not sure but 20rwhp is probably way more than you would really see in 3rd vs 4th.

[bentvalves]

what boost?

[Ca_Silvia]

10 psi

[float_6969]

The opposite is true. The lower the gear, the more HP it looks like you make. An inertial dyno like a Dynojet figures HP based on the RATE OF ACCELERATION. Lower gears accelerate you at a faster rate than a higher gear. This is the problem with chassis dyno's in general. Things as simple as changes in tire pressure or gear ratio's will change the HP that the computer spits out. Obviously raising or lowering your tire pressure doesn't change the HP at the engine, but the dyno thinks so because you changed the rate of acceleration of the drum.

There is a caveat though. Sometimes on turbo cars, the load is so low in lower gears that the turbo can't properly spool up and will make the HP lower that it would in a higher gear because the engine revs slower in a higher gear. This condition gives the turbo more time to react and force more air into the motor, which can increase the HP, assuming the rest of the tune is correct. An NA car will always make more power at lower gears on an inertial dyno.

Another thing to consider is the HP is a function of TQ. The whole purpose of gears is to multiply TQ. So if you are in a lower gear, you have more TQ going to the wheels, which can make it look like you have more HP than you actually have. Sometimes this won't show up on an inertial dyno because they figure everything backwards and actually calculate the TQ from the HP, which is the opposite of some other Dyno's.

I always do all of my pulls in 4th because it's usually a 1:1 ratio and gives the most accurate reading and reduces the amount of drive train losses.

[Ca_Silvia]

I always do all of my pulls in 4th because it's usually a 1:1 ratio and gives the most accurate reading and reduces the amount of drive train losses.

Thats pretty much what my tuner was saying. For actual tuning/baselines he does it in 3rd becasue its quicker but for the final #'s a pull would be made in 4th for the 1:1 aspect.

[Ca_Silvia]

Alright finally some cold hard #'s, Car finally got in to get tuned properly. Yes i know it only pulls to 6100rpm, and that it dips hard at 5200 but we figure with a different gap on the plugs it should smooth out a bit. I already have brand new coils and plugs in there so that why we figure it the gap. And past 6100rpm the curve flatens out and boost dips to 10psi so it wasn't much point of pulling the car past that everytime.

I still can not load the pdf's on to photo bucket so excuse the pic quality.

Finally



I also added a FMIC from the 1st dyno of 180rwhp and this one, so 50rwhp from tune and FMIC,

[float_6969]

Nice!