cam shafts, which side?

[kronix]

hey all, I have a 4age 16v bigport with adjustable cams gears, adaptation ecu and a rebuilt engine and i now have some hks cam shafts that are 256 8.1mm lift and 264 8.1mm lift and i was wondering which side i should put them on as they both have the gear to run the dizzy. After asking a few people and reading different information i have gotten mixed responses and am still confused so any help would be appreciated

Cheers Wade

[ToddW]

hey all, I have a 4age 16v bigport with adjustable cams gears, adaptation ecu and a rebuilt engine and i now have some hks cam shafts that are 256 8.1mm lift and 264 8.1mm lift and i was wondering which side i should put them on as they both have the gear to run the dizzy. After asking a few people and reading different information i have gotten mixed responses and am still confused so any help would be appreciated

Cheers Wade

Hi Wade

I started a thread a few years ago on Toymods titled "Unequal camshaft duration". Check it out as there is a lot of info there. The general concensus is that the larger duration camshaft seems to work better on the exhaust side. A flatter less peaky torque curve. Have a look and be sure to keep us all informed as to how it feels when you drive it.

Cheers

Todd

[kronix]

Hi Wade

I started a thread a few years ago on Toymods titled "Unequal camshaft duration". Check it out as there is a lot of info there. The general concensus is that the larger duration camshaft seems to work better on the exhaust side. A flatter less peaky torque curve. Have a look and be sure to keep us all informed as to how it feels when you drive it.

Cheers

Todd

thanks todd for you reply, im not a member on there but i will see if i can find it, what i might do is put the bigger one on the exhaust side then drive it then change it over and see what i think... does anyone eles have any comments?

Cheers Wade

[assassin10000]

With such small differences in duration between the two it's not something your likely to be able to 'feel' by the seat of your pants. You'd only be able to 'really' see the results with a dyno.

Dyno results in the past have proven differences in the hp/torque curve with slightly different duration cams:
larger intake/smaller exhaust = slightly higher/but peakier
smaller intake/larger exhaust = slightly lower/wider range

Andrew

[--Redwork--]

When I was talking to my engien guru friend about my 4a he said to have the small on the intake side and the larger on the exhaust... Helps keep the intake speed higher and makes it better to drive..

[kronix]

thanks for the reply guys..... hmmmm i think i will put the bigger duration on the exhaust side then... is it better to have both cam shafts the same lift and duration?

[YoShImUrA]

Hi! I posted in the Toymods thread mentioned above, but didn't get any replies so far. Reading above I only got more confused, as I value Andrew's (assassin1000 (http://www.ae86drivingclub.com.au/forums/member.php/4019-assassin10000)) input a lot, but seems to be the opposite of what was said in that Toymods thread.

Let's see if someone in here is kind enough to chip in and contribute to share the knowledge with everyone. =)


I'm having a bit of a dilemma with what cams to use on my 20v blacktop engine.


First, it's got 100mm SQ-engineering velocity stacks (no air filter at the track, which steals about 7hp on dyno), "cleaned up" intake ports, 11.6 CR, 81mm Toda forged pistons, forged MaxSpeeding rods (much better quality than their name or provenance would make you believe), Toda valve springs, lightly ported exhaust ports, K1/pass racing headers, COP conversion. and a Microtech LT-9c standalone ECU...


I first installed Tomei poncams (264 in 256 ex 9mm both) and the car made 142 whp at 7000, with 123 ftlb (167 Nm) @5k RPM to the wheels (remember, still a 1.587cc!) on a dynojet. Low and mid range was like driving a good 2.0l, but I really wanted more on high RPM for the track, where I use it the most. If only I had been building it for a rally car...


So then I fitted a pair of TODA 272 9.2mm. I installed both cams with the pins that allow for the 5deg difference these cams require (they were initially made for the 20v Silvertop), and no, I didn't use adjustable cam gears, as I couldn't afford it at the time and part of me wants to keep VVT for drivability on the road.


On the dyno I first went about dialing in the ignition (I had already street tuned the fueling) and after this I updated the VVT activation from the stock RPM range in the Tomeis, to basically full open on the TODAS. I looked at everything possible to optimize them on my tune (duh!), even by trying a different catback to see any difference (from a 60mm Brave, to a 60mm HKS Hi Power) but I couldn't get anything else out of it.


In the end it had loss up to 15 ftlb in the low and mid range. until they became identical downward slope after 6500 RPM. So, 140 whp at 7500 and 113 ftlb (154 Nm) at 6500 RPM. Same dynojet, but a much hotter day too, from 23C to 39C, which could have been a factor, but not that much, I think.


In retrospect, I wonder if I was running ignition too high (up to 40deg), heating up the engine excessively, but crucially killing power (we had constant pre-ignition monitoring and it never gave any signs of it below 42 deg). No, we didn't have a rolling bearing dyno to find MBT, only inertial. So we reached this ignition tune by doing short dyno runs on a certain RPM range (eg: started from 3-5000 RPM, 4-6. 5-7, etc., and went on and on, and finally double check with full 3k to redline) to find a good ignition value. But I think I need to optimize and test the ignition further. Maybe just doing full runs and just changing 2 deg at a time. In the end and still today, I'm quite puzzled why both cams were limited in exactly the same way after 7k.


Now I have both pairs of cams, and I'm wondering if I fit the Tomei 264 9mm on the intake (with the TODA 272 9.2mm ex) and see where that takes me, maybe with an exhaust adjustable cam gear, to try to extract the most from it, if this would give me a good high RPM combo, but also being able to run with the "OEM" VVT activation and benefits for the occasional mountain drive and city cruise.


So basically, I want to maximize the potential of the engine (those 123 ftlb indicate it's a good engine underneath and bolt-on components, I think) for a bit of everything, from which I can live with not excellent under 3k drivability, as long as it screams to redline. My ultimate goal is 150whp with usability, but anything towards 155, I'm willing to kill a bit of low end for it.


So, ny question is if using the 264 in and 272 ex -with or without the adjustable cam gear- is a good idea (or not), I'm more than happy to hear your advice and/or experience, and some other possible solutions.


Please see the following for dyno results:


1. Tomei poncams graph:


http://www.ae86drivingclub.com.au/dcimages/1/6/7/3/1/560970.jpg


2. Tomei vs TODA (yes, the TODA is the one with the weak low and mid range):


https://scontent.fmad3-2.fna.fbcdn.net/v/t31.0-8/15369111_10154352203772326_4625205205450549120_o.j pg?oh=9587a7e82ad31d1c4a741d03bfa4f843&oe=58FB1C9D


3. Details on both:


http://www.ae86drivingclub.com.au/dcimages/1/6/7/3/1/560972.jpg


Sorry for the poor quality on the last two pics. My hard drive took a dump and I had to rescue these from some random place on my phone.


TIA for reading it all and any valuable input.

[Slimer86]

Vvt killed the low to mid range on toda cams. Air temperature, more so density woyld have a considerable negative impact. My suggestion would be retest in similar environment conditions.
Also, another member on here Seamus had a blacktop with 288 toda cams and had similar issues if I can recall.
Matt mihht be able to fond the thread and link it?

[YoShImUrA]

Updated with good quality comparison of both dyno runs:


http://www.ae86drivingclub.com.au/dcimages/1/6/7/3/1/560982.jpg

[Matt]

This may be the thread you are referring to

http://www.ae86drivingclub.com.au/forums/showthread.php/6707-4AGE-cams-choices-dyno-results-and-discussions!!!

[Slimer86]

Hi Matt, are you able to dig up Seamus' old build thread when he tried toda cams? If I can recall this is the build that went f20c

[Matt]

Yeah it is right Here (http://www.ae86drivingclub.com.au/forums/showthread.php/22813-Wakarimasen)

[YoShImUrA]

Read it all, but no real info on the TODA cams, and he was using 264 on both. Still, a nice build, lol.