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

[jaz_ae86]

AFM is better as you still have flow of air at idle - not that I would choose AFM. 100kw ECU is my pick.
With big cams there is no vacuum for the MAP sensor to pick up at idle.

Plenty of people have run 272's on stock ECU. Billzilla has a audio file of I think 288's, and indeed sounds like a rotor and sounds much like my car when I had 272's on stock cam wheels.

Tho depending on how you set the lobe centres, you could run 288's on standard ECU but really you should have gone aftermarket ECU/emanage with cams that big.

AS for lift: GENERALLY SPEAKING: always think of aftermarket cams like this: under 288, 8.35mm lift is fine. over 288, you gain from more lift. A pair of 264 w/ 10mm lift (meaning you have converted to underbucket shims) is a waste of money - unless its turbo

[Frak]

I recently dynoed a 16V small port with ae111 quads, HKS 264's, 4-2-1's on std MAP ecu, after dialling in cams the thing ran sweet as and very responsive, 90kw at the wheels.

We do quite a lot of flow benching on heads, remember there is no point going any higher in lift if the head cannot flow it. If the head chokes at 8mm, no point putting 10mm lift cams in unless you start modding the head.

btw I have all the runs of the 16v as video files as we changed cam timing, so you can hear the difference with different cam timing. After it was set to optimal, the engine was very sweet

[Wiggles]

Cool, i was looking around the 264 and 8 - 8.5 lift mark, but didn't know if the ECU would even run it (I've got an AFM bigport from an AW11).
So adjustable cam gears are a must-have... Do you sacrifice much bottom end or put the power band heaps further up the rev range on that sort of (264-272) duration?

[aaron]

would that setup gain any/much further from an aftermarket ECU?
post up one of the vids if you have time please

[Wiggles]

2nded, i'd be interested in these. Some dyno graphs would be awesome too, it's difficult to get a straight answer about what power you can expect and where in the rev range you can expect it.

[Frak]

When I get back to work tomorrow, I'll print off the dyno curves, the torque curve was remarkedly flat, this would be a very nice street engine.

I'll try and upload some vids.

The problem with running a MAP ecu with cams, is that people will tee all throttles together and one line to the MAP sensor(nothing wrong with that) BUT the pulsations acting on the MAP sensor will alter it's voltage, the ecu see's this voltage change and alters fuelling accordingly(this really throws the idle around as the a/f ratio is changing), so you need some form of pulsation dampener between the throttle vacuum lines and the MAP sensor, now of course running hot cams will reduce the amount of manifold vacuum at idle, the ecu will read this as the engine being under load(more than idle) and adj fuel to suit, which means a rich mixture at idle and light load.

It also reduces the operating range of the MAP sensor, the standard MAP sensor(NA engine) will read from 0kpa to 100kpa absolute, approx 0v-5v, if the standard engine uses the majority of this range in standard specification, so by this I mean, as load changes the voltage changes, if you were to have the engine idling at say 40kpa, this will equate to a certain voltage, if now we change the camshafts, at idle the manifold vacuum may now be 60kpa(full load being 100kpa), see how the useful range of the MAP sensor is narrowed even though the operational range of the engine(rpm etc) has remained the same. the cammed up engine sees 60kpa at idle, the ecu thinks 60kpa is light load and adjusts fuel accordingly.

Altering the cam timing(reducing overlap) can go someway to getting back some manifold vacuum and having the engine run sweeter.

Another negative by-product to running hot cams, is the lack of vacuum for the brake booster, you may think this trivial, but it can have some unwanted side affects

We went from having an engine that was NOT happy below about 3500rpm and a very rich crappy idle, to something that was very responsive and very sweet right through the rev range.

When you see the torque curves, you will agree.

Aaron, for sure I think there are some gains to be had by using an aftermarket ecu, the a/f ratio was actually quite good, better than I thought it would be!!

After we dialled in the cams, the a/f at idle was sweet, about stoich, under light load it was stoich and under full load around the 12.8/13.0:1 which is sweet for an NA engine.

I have had the lad check the total timing and see how much he's running, this will also be another area we can pick up.

We tried some different length ram tubes(in free air, this is, no air box), the engine preferred long tubes, I have found short tubes work well when used IN an airbox(hermholtz tuning etc).

[slide86]

oh man, i love reading posts from people that actually know what they are talking bout....

a refreshing change sometimes. good work mate!

[Sam-Q]

Frak don't ever leave this forum!

I agree with your points, the resonance issue with the vacuum signal can be helped by having a large mini-plenum to joint all the signals together, or as some people do run all the throttles together and then put the pipe through a small plastic fuel filter. Apparently it evens the pulses out quite nicely and solved a rough idle completely from someone on this forum.

Running a vacuum signal for brakes isn't a big deal as I am like many others with 20V engines only using the vacuum bleed off number 1 cylinder for my booster. Now that I have the right master cylinder size for my brake master I don't have any issues. Although depending on the lobe center angle on the engine in question I would likely have a higher vacuum signal because I am using stock 250 degree @ 0 lift cams.

I was thinking that it might be ideal to have something like the 20V engines have for the idle control in that it has an integral mini plenum built into the top of the intake manifold. If someone took air bleeds off all four cylinders and put them in a pipe of lets say 20mm, then it could in theory be used for both the brakes and a vacuum signal. Do you see any potential issues with this?

[kool mints]

ok guys, did not wanted to start a new thread.

I'm also looking at getting some cams shafts for my JDM AE86 GTV kouki 4AGE 16v blue-top.

So far i've narrowed it down to Tomei Poncam which is 264 degrees ex & in with a 8.1 in lifts!!

Wanted to know if anyone is using these set of cams?? can shed there experience??

Will it be able to ran these set of cams with JDM ecu without going aftermarket ecu?

Do these cams just bolt on? if not what sort of bits do i require?

What sort of gains would i be expecting, i want somewhere between bottom and mid-range gain, not to fuss about top end as it street car.

sorry for those million questions, also did quick search, could not find what i wanted.

Thanks guys.

Cheers

[trueno85]

pon cams are actually developed to be able to run on a standard ecu and springs but for ease of mind may as well change the springs. with poncams they have a good midrange and a good street cam

i used to run them on my sr20 and they were great for the street