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Discussion Starter · #1 ·
Hey there, I'm currently tuning my mr2 on a link g4+ pnp

I was wondering if someone could give me a rough timing map for my setup...right now I'm sitting at 13 psi with 15*-16* of timing. I was wondering what's people's recommendations on what the timing should be referenced to boost roughly. On 91 octane =(

Mod list
92 jdm Gen 2 3sgte
Fully built head/port and polished
Gsc 268 cams (set to 0, I was wondering if I should retard the exhaust cam)
HKS cam gears and belt
3 inch dp and exhaust
Greddy intercooler
Cosmetic 1.3mm headgasket
Sard 800cc injectors
Aem fpr
New oem cap rotor, spark plug wires
Bkr7e ngk spark plugs.

Please and thank you.
 

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I have a very similar setup as you but I am running E85 @ 15psi. The timing values you are reporting during full throttle is about right for your setup. I have put on several hundred miles on my setup without damage and it has two or three more degrees than your map. If the rest of your map is scaled correctly it is safe enough to drive to the dyno.

I'd recommend getting a cam degree kit. I've tried to eye-ball cam install may times and I usually don't get it aligned correctly (I'm off a tooth retard or advance).
 

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Discussion Starter · #3 ·
I have a very similar setup as you but I am running E85 @ 15psi. The timing values you are reporting during full throttle is about right for your setup. I have put on several hundred miles on my setup without damage and it has two or three more degrees than your map. If the rest of your map is scaled correctly it is safe enough to drive to the dyno.

I'd recommend getting a cam degree kit. I've tried to eye-ball cam install may times and I usually don't get it aligned correctly (I'm off a tooth retard or advance).
I have a kit, I was dreading doing it because of the amount of room on the mr2 lol.

Was there a noticeable difference when you degreed the cams?
 

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It is a lot of up and down to degree cams with motor in the car. I noticed a difference in idle quality and exhaust sound, vacuum amount, general drive ability, and responsiveness while having my cams degreed to different settings. When I first installed the motor without degreeing, the motor was peppy mid rpm and fell off quick in high rpms. The power curve was very peaky. This is a decent reference on what adjusting cams does to power delivery over rpm: Cam Gear Tuning - Tuning Advance, Retard, and Overlap for Power

For now, I set them based on the recommendation of engine builder and recorded lobe separation angle, duration, and overlap with the chart below (that way I can remember where they are set). When I hit the dyno I will adjust them to find the optimal characteristics based on my preferences.

 

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My gen 2 3S-GTE with gen 3 GTE cams likes about 26-27 degrees BTDC timing on 92 octane E10 fuel at 100 kpa (0 psi boost). On pump gas it seems to want a really high level of timing retard compared to modern engines. I pull about 1 degree/psi boost, a little lower than that at low boost, then a bit more at high boost. That's inline with your timing numbers, but what really drives it is I'm reading crank position from the stock distributor, which has a ton of timing flutter and it'll still knock occasionally due to this. If I had a crank trigger sensor I think I could run closer to 0.9 deg/psi and be safer than occasionally catching the knock via the sensor. I also run cyl 2 and 3 about 3% richer and run less timing on them to get all cylinders about equal chance of knocking (have ATS intake manifold, so flow should be even-ish).

The car will still knock occasionally up to about E60 with ~0.8 deg/psi of retard and the same 26-27 deg at 100 kpa timing, but it's not very common. Kinda surprising it can still knock at that ethanol content, but it shows the timing flutter. It has taken 20 psi from my EFR 6758 with the stock bottom end, but that's largely with a modern EMS (AEM Infinity) keeping the knock under control. Do this with an older EMS and let it knock all the time and it wouldn't last long at all IMO (like most the people boosting 3S-GTE's to the moon in the early 2000's and blowing engines every year).


FWIW, an SR20DET will tolerate about 0.1-0.2 deg/psi less timing retard on pump gas, and with an SR20VE head (think like K-series in flow) it'll do a solid 0.2-0.25 deg/psi less retard and actually wants to idle at 4-5 deg timing the combustion chamber is so much better for combustion kinetics.


That's my 2 cents - if you really want to mod a 3S-GTE, you need to accurately know the crank position.
 

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Is there a noticeable difference in knock control quality between infinity and series 1? Assuming utilization of stock Toyota sensor for both applications?
 
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