Low Boost, High Timming

[90AWDTalon]

I installed a new engine two weeks ago do to a spun bearing. I decided to try out the stock 14b that came with the new engine do to the better index I get for autoX, E street prepared vs. street mod. To be in compliance with the street prepared rules I'm running stock boost. I end up creeping to 15psi at the to of the rev range. My previous setup was a ported 16g @ 24psi. I was running such high boost because that was where I was creeping to so I set it there and tuned in lots of fuel and retarded the timming quite a bit in the mid range, I didn't need to retard much at the top though. I added an EVO o2 housing at the same time as I installed the new engine, now the creep is much more reasonable.

Do to running so much less boost I've been able to lean things out about 20% and actually advance the timing some. Below is a pull I just made, I'm advancing timming through my emanage and becuase it alters the timming after the ecu you have to add the values from the emanage to these from my logger. I have the timming advanced 1 degree from 500rpms - 5500rpms, 2 degrees from 5500rpms - 6000rpms, and 3 degrees from 6000rpms on up. So I'm getting between 23 and 27 total degrees of timming. This is on 92 octane.

So my main question is has anyone else gone this route, low boost and lots of timming? If so what kind of results did you get; times, dyno, or just seat of the pants? I'm not done tunning yet so there still might be room for even more timming. Right before the log I added 1 degree through out the whole rpm range, I couldn't believe how much of a difference only 1 degree made. Makes me wonder what a couple more degrees could do for me.

RPM Knock Timing O2
4469 0 24 0.84
4594 0 22 0.86
4656 0 22 0.88
4844 0 22 0.88
5000 0 22 0.88
5156 0 22 0.88
5219 0 23 0.86
5312 0 24 0.88
5500 0 24 0.86
5719 1 24 0.86
5812 1 24 0.86
5969 0 24 0.86
6031 0 24 0.86
6188 0 23 0.86
6312 0 22 0.86
6469 0 21 0.86
6469 0 21 0.86
6562 0 20 0.86
6688 0 20 0.86
6781 0 21 0.86
6906 0 20 0.86
6906 0 20 0.86

 

[iamtall77]

I'm not that experieinced, but you can only advance timing so much. Even if you don't get knock, you might not be helping the power. According to your O2s you're a little lean, but don't go by O2's alone. To get any deffinate answer, you'll have to hit the dyno. The great thing is with your emanage is, that you can pick and choose where to add or subtract a degree or two. Back in the day with carburators and distrubutors, you could only change the base timing and hope the vacuum retard works right. Keep everyone updated. You might even try the extreme forum and see if some of those guys have done this before.

 

[Kevin Jewer]

I'm not done tunning yet so there still might be room for even more timming.

Not trying to pick on anyone, but a double m or n makes the vowel long. Or is it short. At any rate, there should only be one n or m. After reading timming 15 times, the quoted line above got a little chuckle out of me No offense intended, just sharing some spelling info as well as some automotive info


Back to the point! I dont think anyone has realy tried high timing and low boost. High boost and low timing makes more power every time I have tested it both ways. You have a special case though, so the best thing to do is to continue doing what you are doing. Add some, log it, and see what the results are. Just be careful with high timing on pump gas. At 28 degrees on pump I took out 3 cylinders. Base was at 10 for some reason, so I thought I was only at 23. That'll teach me! Looking at your log, I would recomend not adding more timing until after peak cylinder pressure (or torque peak if you've dynoed), I would say after 4k on a 14b. As rpm gets higher, you can be more agressive with timing. At some point though you will reach a point of diminishing return, and the mechanical limit, on that particular fuel. And when you get close to that limit, things can get ugly real fast. A matter of 1 or 2 degrees can be huge, while at 18 or 20 degrees 1 or 2 degrees is a drop in the bucket. So proceed cautiously, and good luck! Keep us posted on the results if you do dyno or go to the 1/4 mile, I'd be curious to see how it runs setup like that.

 

[Nos~4G63]

I have a friend with a 14b and 850's. He is using a MAFtranslator to take out fuel. He is only boosting 7psi but is getting 28degrees of timing advance. I have read that such a great compensation for fuel causes the ecu to use timing maps from cruising.

With only 7psi from the 14b and 28degrees of timing the car made 278whp!

 

[kyle h.]

I have read that such a great compensation for fuel causes the ecu to use timing maps from cruising.

this is correct because, the ECU uses the MAF signal to help pick what table it should be in for the timing. when you're compensating for larger injectors the signal gets lower and lower, so the ECU thinks you're at a lower 'timing table/cell'. This is why getting bigger injector, even if you don't need them can help power significatly.


i'd keep increasing the timing on ur ride until you get towards 26-27ish. that seems pretty high, but reasonable.

 

[kpt4321]

Looking at your log, I would recomend not adding more timing until after peak cylinder pressure (or torque peak if you've dynoed), I would say after 4k on a 14b.

Peak VE is closer to 5k RPM, it's more dependant on cams I think.

 

[kpt4321]

I have a friend with a 14b and 850's. He is using a MAFtranslator to take out fuel. He is only boosting 7psi but is getting 28degrees of timing advance. I have read that such a great compensation for fuel causes the ecu to use timing maps from cruising.

With only 7psi from the 14b and 28degrees of timing the car made 278whp!

First of all, you don't want to run injectors that huge with a MAFT, or any other decive that uses airflow for correction (VPC, SAFC, etc).

Second of all, there is no "cruise" timing map, there is just one big timing map that is indexed by load.

Thirdly, I am doubtful he made 278 true wheel horsepower at 7 psi on a 14b. Either it didn't happen, or there is something else you forgot to tell us (high compression motor, stroker, etc).

It would be very very hard for a 2.0 liter 4G63, even one with big cams, to flow the air needed to make that kind of power.

 

[Kevin Jewer]

Peak VE is closer to 5k RPM, it's more dependant on cams I think.

Hmm. You might be right kyle. Cams will certainly play a big role. Its been so long since I had a turbo that spooled at a reasonable rpm I cant remember. But on 20g and up, air/rev peak was always when peak boost hit. The tdo6h 20g came on around 4k on the 2 liter, and the 56 trim around 3700 on the 2.3. In both cases though, even with 272s, peak air/rev was at the same rpm as the full boost point.

 

[kpt4321]

Boost spike. Peak airflow per rev will not coincide with peak VE if your boost is spiking.

My car's torque peak is clearly at 4600 rpm on the dyno chart, and that's with bad boost falloff. A turbine housing that didn't suck would probably have the torque staying up to 5000 rpm os so.

 

[90AWDTalon]

I was driving on the freeway today in 4th gear and was sometimes getting 5 - 6 counts of knock around 4500rpm's at full throttle. I think I'll take 1 degree back out in that area and I'm thinking about adding another degree towards the top.

Kyle, I know that you have messed around with timing quit a bit, I was wondering what your opinions are on this subject? Am I going in the right direction? How far can I take things? If I go in small increments will I notice a small amount of knock to warn me I've gone to far or is there the possibility of going from no knock to damageing the engine with a 1 degree change. I got a little nervous after reading 95GSXRacers post, as I'm only 1 degree lower than what he had when he killed his engine. I have a 1G and his is a 2nd Gen so I have lower compression, but I don't know if the difference is big enough to not cause problems for me.

Sorry about the spelling in the first post. I'm a crappy speller, always have been, and probably always will be.

 

[kpt4321]

Keep in mind that when Kevin killed his motor, he was making probably twice the horsepower that you are. With a stock turbo, your situation is different.

Take out a degree of timing where you were knocking, and add a degree up top to see what happens!

 

[Kevin Jewer]

Yes, good point. I used to get 12 or 12.5 degrees of knock retard (I think that must be the max, I saw it often) all the time when I was around 45 lbs/min and lower. Since approaching and going over 60, I've had terrible luck with detonation. Not to get off topic, but I just found out my current motor is junk after the 11.3 at 126 pass, compression is 0-50-0-200. Same cylinders 1/2/3 again. No knock at all. Timing at 21 degrees. boost 29 psi. Airflow 64.x lbs/min. 117 octane race gas. I put some info on my page here: http://www.posracing.net/AFR.html Cant always rely on knock. But at your level you can be more aggressive, just keep your eyes open and keep that timing value realistic. There is a point of diminishing return on every setup, and wether or not thats before or after the motors limit is where the danger lies.

 

[Nos~4G63]

My friends car has a ported 2g mani, ported turbine housing, ported 02housing, 3'' exhaust, crane cams, front mount, blow through maf, 850s, aeromotive afpr, and his motor is bored 60 over with 8.5 or 9-1 wiseco's.

Maybe the Dyno was off, It was Dyno'd at Twilight Performance in Miami.