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Well said Abacus, but some of the other remarks are generic, like "too much timing"! It's all relevant to the amount of torque that an engine can withstand. Fact: well built 4G63s with quality internals are often made to withstand tremendous amounts of torque & is used in various motorsports & drag applications. Giving that fact, often as a tuner your timing is only limited by knock when using pump gas or by MBT when using knock-free hi oct fuels.
Well said Abacus, but some of the other remarks are generic, like "too much timing"! It's all relevant to the amount of torque that an engine can withstand. Fact: well built 4G63s with quality internals are often made to withstand tremendous amounts of torque & is used in various motorsports & drag applications. Giving that fact, often as a tuner your timing is only limited by knock when using pump gas or by MBT when using knock-free hi oct fuels.
Its hard to explain but just because an engine will take 19* out the top on one 3rd gear hit doesn't mean you leave it at 19*. MBT is a slippery slope for some people.. An example, If it picks up 20 per degree on turbo xxx and then it only picks up 10 per degree , then go back to the lower number that gives you more margin for error and lifespan. I've seen plenty of these cars with 15* out the top live a long time at 800hp+ @8000 .
You don't need to rattle the engine at the limit all the time.
Its hard to explain but just because an engine will take 19* out the top on one 3rd gear hit doesn't mean you leave it at 19*. MBT is a slippery slope for some people.. An example, If it picks up 20 per degree on turbo xxx and then it only picks up 10 per degree , then go back to the lower number that gives you more margin for error and lifespan. I've seen plenty of these cars with 15* out the top live a long time at 800hp+ @8000 .
You don't need to rattle the engine at the limit all the time.
Exactly. We can say this many ways:
1. A dynometer max output tune is generally NOT safe for the street! Due to the differences in rate change of RPM per vehicle loading (gear ratio vs road speed vs time) the conditions of street will rarely mimic the dyno situation well enough to keep a 'dialed' result.
2. As an engine spends more time at WOT the chamber temperature will need to be reconciled with ignition timing, i.e. a 4th or 5th gear pull by itself vs 1st, 2nd, 3rd, then 4th gear pull last, the sequential nature loading the engine through each gear will produce more heat for high rpm in the final gear (or even overdrive) thus the max ignition timing for a max output dyno pull using a SOLO gear run will ALWAYS be higher than the max ignition timing satisfactory useful for sequential loading via EACH gear in a real street or racing application.
3. General rule: The only cars that should get MAX timing are COMPETITION cars. In other words, the only time we need to squeeze the last 2% or 3% of power by forcing high timing values from a forced induction engine are when you are racing for MONEY and trying to WIN with high stakes. Otherwise its JUST A TEMPTATION OF FAIL and unnecessary abuse!!!
These cars have old engines that don't need a lot of timing to run. The only trophy you get for a high timing score is an expensive one.
I've run my car 70+ pulls on the dyno . There isn't a huge change from pump gas to race ethanol for timing with a small turbo/backpressure.
You can just about start off at 2-3* at 3500 and build an easy ramp to 5-8* at 5500 then to 13-15* + on most of these cars. A larger turbo with less back pressure may be able to run more but never get carried away. If you have higher or lower then stock compression that also plays a big role.
The real test is putting it on the dyno and running it back to back to see what timing yields decent results . You don't just keep adding timing to chase small gains. Looking at plugs and smoothness is also a good idea.
exactly my car is tuned this way
on pump at 4500 rpm on a black I am at 2* at around 6000 and 75000 im at 12
Well said Abacus, but some of the other remarks are generic, like "too much timing"! It's all relevant to the amount of torque that an engine can withstand. Fact: well built 4G63s with quality internals are often made to withstand tremendous amounts of torque & is used in various motorsports & drag applications. Giving that fact, often as a tuner your timing is only limited by knock when using pump gas or by MBT when using knock-free hi oct fuels.
My remarks may sound generic, but they come with a lot of experience. I'm not here to explain everything. But anyone who is a half decent 4g tuner knows that timing table is wrong and dangerous for any 4g engine.
Torque and timing are not related when it comes to an engine build and what the engine can withstand. Sure, it can handle 700wtq, that doesn't mean it can take 15* of timing at 5500rpm at 30psi.
Just for context, I'm pretty sure the goal is to time the ignition so that peak cylinder pressure occurs 15-20 degrees ATDC. That sound about right?
Yes. around 15* ATDC is the generally accepted ideal point for peak cylinder pressure. I've never seen data on these engine with a cylinder pressure sensor, so most tuners go by the rule of thumb @Abacus posted which is that you should pick up ~20whp with adding a degree of timing. If you don't see that gain, the timing really doesn't need to be there and should be backed off.
What is the ballpark relationship between timing and boost on E85? Say, between a 25 psi tune and a 35 psi tune?
It really doesn't change much. Like you're not going to go from 15* at 8k at 35psi to running 20* because you dropped down to 25psi. Timing is more of a "where is it happy" and boost is what you use to make power. For road course work, usually run a little less timing, but not a lot less (I think my track tune has like ~3* taken out across the board above 4500 or 5000rpm), to reduce heat. Its a balancing act of less heat in the chamber and raising EGT when running less timing.
Am I being too soft on the timing in the 4000-5500 range?
Relevant details:
2.4L IX 9.x to 1 compression
MIVEC rolling back towards zero by 340 load
6466 ETS kit
E70(verified) fuel
WGDC nearly zero at 4krpm and ramps in hard by 8000rpm avoiding low rpm boost spike
On the log below I was riding the brakes at ~4krpm to build up some turbo speed before starting the pull.
Don't mind the 6000rpm 180% load area, I've smoothed that out already.
