4.0 Dyno Comparisons: Newcomer Racing

[psrivats]

This is a stock timing table.

View attachment 336307

Timing is very, very conservative under medium to high load. When you need more power the stock table is reducing advance as low as 16.5 degrees with modifiers. At highway speeds the stock timing table on my Jeep would start pulling timing as load increased and it seemed to not make any more power past half throttle. The additional advance helped considerably above 60 MPH. The changes I made to timing is all in the lower right. I added more than 10 degrees in the last column above 2240 RPM and blended the cells back to the left to the highest advance of the stock tune.

Do you think what the factory did was controlling emissions? There must have been a reason for the deliberate choice from the engineers and I really wonder what it is.

 

[MikeE024]

Very few NA engines in history have ever responded well to bolt-ons...

FI engines are the other hand response very well. I recall one of the popular hot rod magazines at the time, perhaps even "Hot Rod" itself, did a "bolt-on challenge". They tested a handful of cars popular at the time, including one of the staff members' turbo AWD Eclipse. It held the record for "HP/$ investment" for a long, long time. I recall one of the worst (in the "follow up" article many years later) was the Honda S2000, where it took something like $900 for +4HP...

My buddy’s uncle was a pro drag guy (world record holder at the time) in his modified Talon.

He gave my buddy’s older brother his night rider looking all black awd boosted Eagle Talon (eclipse twin).

To this day, no vehicle tossed me around like Miah’s Talon. My buddy’s younger brother then killed it after killing “the beast” an old k5 blazer.

 

[astjp2]

Very few NA engines in history have ever responded well to bolt-ons...

FI engines are the other hand response very well. I recall one of the popular hot rod magazines at the time, perhaps even "Hot Rod" itself, did a "bolt-on challenge". They tested a handful of cars popular at the time, including one of the staff members' turbo AWD Eclipse. It held the record for "HP/$ investment" for a long, long time. I recall one of the worst (in the "follow up" article many years later) was the Honda S2000, where it took something like $900 for +4HP...

My 572 hemi would disagree

 

[Mike_H]

This is a stock timing table.

View attachment 336307

Timing is very, very conservative under medium to high load. When you need more power the stock table is reducing advance as low as 16.5 degrees with modifiers. At highway speeds the stock timing table on my Jeep would start pulling timing as load increased and it seemed to not make any more power past half throttle. The additional advance helped considerably above 60 MPH. The changes I made to timing is all in the lower right. I added more than 10 degrees in the last column above 2240 RPM and blended the cells back to the left to the highest advance of the stock tune.

What do the columns denote? I assume the rows are RPM and the field values are degrees advanced. I know its load, but is the value coming from the MAP (or MAF, I'm not sure what Jeep uses) or some other calculated value?

Do you think what the factory did was controlling emissions? There must have been a reason for the deliberate choice from the engineers and I really wonder what it is.

Probably the factory is being conservative to control knock (pre-ignition). The 4.0 doesn't have a knock sensor. A modern engine will run more advance and start pulling timing in High load situations when the knock sensor is triggered. You gotta remember, in the early 90's when this engine management was put together, the computers were WAY less powerful and FI was just becoming mainstream. There has been a whole bunch of development in that area. It doesn't surprise me that its very conservative. If you don't really know the whole in and out of something, you're not going to push the limits...especially in the arena of reliability and making millions of engines that don't have warranty concerns.

 

[ColoJeep]

My 572 hemi would disagree

I Totally agree , and let's not even talk about h.p. / dollar on a small block Chevy or LS motor.

 

[SkylinesSuck]

What do the columns denote? I assume the rows are RPM and the field values are degrees advanced. I know its load, but is the value coming from the MAP (or MAF, I'm not sure what Jeep uses) or some other calculated value?

We use MAP and that value is usually in kPa but not sure what that is. Different tuning platforms use different scales sometimes.

Probably the factory is being conservative to control knock (pre-ignition). The 4.0 doesn't have a knock sensor. A modern engine will run more advance and start pulling timing in High load situations when the knock sensor is triggered. You gotta remember, in the early 90's when this engine management was put together, the computers were WAY less powerful and FI was just becoming mainstream. There has been a whole bunch of development in that area. It doesn't surprise me that its very conservative. If you don't really know the whole in and out of something, you're not going to push the limits...especially in the arena of reliability and making millions of engines that don't have warranty concerns.

Exactly my thoughts.

 

[Brianj5600]

What do the columns denote? I assume the rows are RPM and the field values are degrees advanced. I know its load, but is the value coming from the MAP (or MAF, I'm not sure what Jeep uses) or some other calculated value?


Probably the factory is being conservative to control knock (pre-ignition). The 4.0 doesn't have a knock sensor. A modern engine will run more advance and start pulling timing in High load situations when the knock sensor is triggered. You gotta remember, in the early 90's when this engine management was put together, the computers were WAY less powerful and FI was just becoming mainstream. There has been a whole bunch of development in that area. It doesn't surprise me that its very conservative. If you don't really know the whole in and out of something, you're not going to push the limits...especially in the arena of reliability and making millions of engines that don't have warranty concerns.

My tuning software uses Torr units. The columns are MAP in torr. I have no idea why Torr is used.

I agree that lack of knock sensor caused the conservative tune, but playing with engine it likes timing.

 

[psrivats]

What do the columns denote? I assume the rows are RPM and the field values are degrees advanced. I know its load, but is the value coming from the MAP (or MAF, I'm not sure what Jeep uses) or some other calculated value?


Probably the factory is being conservative to control knock (pre-ignition). The 4.0 doesn't have a knock sensor. A modern engine will run more advance and start pulling timing in High load situations when the knock sensor is triggered. You gotta remember, in the early 90's when this engine management was put together, the computers were WAY less powerful and FI was just becoming mainstream. There has been a whole bunch of development in that area. It doesn't surprise me that its very conservative. If you don't really know the whole in and out of something, you're not going to push the limits...especially in the arena of reliability and making millions of engines that don't have warranty concerns.

My tuning software uses Torr units. The columns are MAP in torr. I have no idea why Torr is used.

I agree that lack of knock sensor caused the conservative tune, but playing with engine it likes timing.

Thanks guys. This stuff is really fascinating to think about.

 

[Jezza]

I know SCT uses Torr, but I'm not sure why.

The factory has to tune for all possible scenarios. That includes poor quality gasoline, altitude, emissions, temps, driving styles and others. The result of that is usually a fairly conservative tune.

 

[Jezza]

Interesting but then I don’t get why the S2000 is a sooo common platform for upgrades…

My S2000 loved bolt-on... nitrous.

 

[pc1p]

My 572 hemi would disagree

You may have missed the "very few" in my original comment

That said, "pics or it didn't happen"! What bolt on mods did you do? What were the gains?

I Totally agree , and let's not even talk about h.p. / dollar on a small block Chevy or LS motor.

I've got a photo of me holding a spin wrench, while wearing only a diaper, standing on a folding chair, next to a BBC. In the time since, I've yet to see meaningful gains from bolt-on mods, even on Gen III/IV motors. That said, feel free to provide counterpoints...

HP/$$ is a different topic and both the Gen III+ Hemi and LS are fantastic in this area (particularly when forced induction comes into play). Even still, these motors respond significantly better once you start swapping internals, particularly the cam, to anything you can bolt on the outside (sans a Chinese Choo Choo or two).