4AGE cams......choices, dyno results and discussions!!!

[DAMO46]

so reading through that, is it better to have a after market computer eg apexi power fc or a stock ecu?

[trueno85]

there's no adjustment on the stock ecu though so it would be better if you had it

[Frak]

Thanks guys.

I have printed off the power, derived torque and a/f ratio's of the following runs;

Standard JDM AE86 bigport
mildly modded JDM bigport(small cams, headers)
ST 20V(exhaust/pod)
BT 20v(velocity stacks)
said 16v small port(cams etc)

I will scan tomorrow and post with a discussion on each, Sam Q I will be interested in your responses as obviously you are a 20v fan

All torque curves are "derived" torque. For those that may not of used a chassis dyno before, the torque figure that is given on a dyno printout includes gear ratio multiplication.

Some people will comment that they have seen a power/torque curve and that the torque was some incredibly high figure for that particular engine, what they don't understand, is on a chassis dyno we have to take into consideration the multiplication of torque by,
1. the gear box ratio
2. the diff ratio
3. the ratio of the tyre to the roller

I will try my hardest to dyno manual cars in 4th gear as this is direct 1:1, unfortunately by design, fwd gearboxes will not have this direct straight through so I try to do it in a gear that is as close to 1:1 as possible.

Even if I do dyno in a direct gear, you still have the torque multiplication of the diff ratio and the tyre/roller interface.

Auto's can be a problem, especially autos that bloody want to kick back regardless of what speed you start the run at! and auto's have another torque multiply....the torque converter.

One must always remember that you can multiply torque but you can NOT multiply power by using gearing, for example

If I have 100NM coming out the back of the crank and into a gear ratio of 2.0:1, I now have 200NM coming out the back of the gear box, if I have a diff ratio of 3.0:1, that 200nm now become 600NM, this is why it is much easier to start off in 1st gear than 4th gear. Lets just saw I have 100kw coming out the back of the crank, ignoring frictional losses, this 100kw should stay at 100kw thru the gearbox and 100kw thru the diff ratio.

Now I'm heading somewhere with this, hang in!

Now often people comment on the huge amount of torque they have after being on a chassis dyno and call bullshit, so we have a function called derived torque, basically after a run we have the full logged power data, but we also need an rpm input(which I try to log every run, infact I will try and log as much data as possible, injector duty cycle etc etc), using these two, it works the power/torque equation backwards and basically gives us torque at the wheels IGNORING gearing!!!

So tomorrow when I post up the scans, you can see the derived torque of these engines, I look forward to the comments people make, but lets just say the 16v's torque curves are overall much flatter, the ST is quite flat but the BT is not as smooth but quite a bit more torque everywhere.

I guess we have probably about 40 different 4age powered vehicle runs and I have picked what I consider to be the average for each type of engine.

[Frak]

Damo46, if you can afford it, some form of aftermarket ecu(power fc, e manage, motec, haltec etc) is always going to give you the ability to optimise the a/f ratio and ignition timing/curve to suit your modded engine.

The standard ecu(give or take a little) is, well, optimised for the standard engine.

I have used e-manage and for the price really thought it was good value, easy to use, make sure tho you get the ignition harness so you can alter fuel and ignition.

I also have the FC-logit lap top software for the Power FC and it makes tuning a power FC sooooo much easier than that bloody hand controller

of course my fav is Autronic

[Sam-Q]

well this will be interesting, please post the exact setup/mods the each engine had at time if possible.

As for my opinion: a fan? maybe, an expert.. no

With the aftermarket ecu's I think it often pays using something locally made. Its gaurenteed to be in english and support is much easier. I like the idea of driving 10 min to the local dealer of my model of ECU to buy parts or drill him with questions.

[Sam-Q]

where do you want your power to be?

are you prepared to lose low down power?

have you considered a local grind?

and welcome to the forums

[slide86]

frak, if anyone ever asks you to dyno a jzx100 auto, just make sure you strap the bugger down damn tight....

they LOVE to kick back.....sometimes it annoys the crap outta me. we had to dyno my car in second and couldnt get WOT because it wanted to kick back to first. thats why my dyno sheet shows 600NM of torque. i think thats a bit ambitious!!

I also agree that collecting the most data possible when doing runs is important. i laugh when i see no ambient temp correction, manifold pressure/vacumn. i mean, how is it supposed to be accurate when the machine doesnt even know what its supposed to be reading???

emanage is real good bang for buck and is highly regarded amongst us jzx100 boys. its either that or a plugin power FC, but the power FC messes with the auto shift point to much

im really looking foarward to these results, it would be good to see the difference between a 4a with forced induction and some cams/gears....as this is the setup i am using on my engine. HKS 264 8.3 cams and HKS cam gears....i want to get the most out of the boost.

[Frak]

Slide86, I have done a jzx100 manual and from memory didn't have any problems with wheel spin, I will adjust the ramp rate to suit the power level tho.

If a vehicle has a very powerful engine or an engine which accelerates very fast, you should adjust the ramp rate to suit, for example,

What is ramp rate, this is how fast the dyno allows the car to accelerate on the rollers, a slow ramp rate would be 5km/h/sec, which means that every second the vehicle would increase it's speed by 5km/h, a fast ramp rate is say 18km/h/sec. Get a picture of the difference.

Lets just say we have a powerful engine that comes on boost very quickly making lots of power/torque, we would need a faster ramp rate, if I tried to use a slow ramp rate with a fast accelerating engine, the wheels would out run the speed at which the dyno is unloading the rollers and we would end up with wheel spin and end up with a lower reading.

At the other end of the spectrum, imagine an engine with very little power/torque, if I had a very fast ramp rate, the wheels would never load the rollers until maybe near the end of the run, so we would end up with a power/torque curve less than it actually had.

Sometimes tho it is necessary to change the ramp rate to one which maybe slower, if we were to really load the engine and test if ignition timing etc was correct, a slow ramp rate would replicate going up a long steep hill, of course longer ramp rates mean the run takes longer, which may put extra stresses on gearboxes/diffs/cooling systems.

Our Dyno(Mainline) also has an inbuilt weather station which is constantly updating baro pressure/temp/humidity, this automatic/constant updating also removes an area to be able to 'cheat'.

When dynoing a sportsbike, say a GSXR1000, a fast ramp rate is necessary due to how hard the engines come on power, if the ramp rate is too slow, the reading will be down and usually you end up with one shredded tyre aswell.

With regards to the 4age power/torque curves, it wasn't until I was driving home that I thought I should of printed out a GZE one so the comparison of torque could be made.

Sam, I will try and put as much info as I possibly can with regards to engine specs.

[slide86]

the reason that i was saying strap it down is cause the first auto we put on, wasnt tight enough and kicked back to 1st......was a bit of a moment for the owner and the operator....

i guess thats why alot of clutches and auto boxes get fried, due to incorrect ramp rates causing excessive stress on the driveline???

so many cars come into work with stinking clutches after just having LS1 edit done..."it never did that before it was on the dyno" is the most common thing customers say. lol

[Frak]

for sure, manuals make it so much easier, unless you have an auto that will lock into a particular gear, with some of the LS1 software you can lock the auto into what ever gear, makes it so much easier.