BadAss SRT-Z - 2.4L / A568 - Update!!!

[Speedeuphoria]

aaron, so are you saying that the map posted is way too aggressive?

No he is saying that people use map clamps and dtec's or what have you to pull fuel by telling the map its at a lower psi than it really is. So the timing goes up because it thinks its at a lower psi. Which again is why they have the oil pump and ringland probs if they dont know what they are doing, which many dont.

[8valves]

No he is saying that people use map clamps and dtec's or what have you to pull fuel by telling the map its at a lower psi than it really is. So the timing goes up because it thinks its at a lower psi. Which again is why they have the oil pump and ringland probs if they dont know what they are doing, which many dont.

Yup, that's what I was referring to.

[8valves]

Its no 8valve

My vac and 100Kpa values are basically the same as that map(basically 2 deg less except for idle)

This was posted by Kevin Davis on TD awhile ago

"Yes he is talking total timing,I talked with bill hahn and some other people darrel cox etc. about total timing with the pent roof stlye head when I was building my 2.4 dohc.This is what bill hahn told me,@ 8.6:1 comp. with the sc6152 turbo 15 psi is max with pump gas @ 15 to 17 total if you go to 21 psi 110 octane, 26 psi 114 anything else c16. I found that with the automatic its more like 13 or 14 I was getting slight knock at 15 degrees.Like brian said the pent roof style head is so efficient and such a fast burn head with its central plug location it just doesnt need the advance.Darrel cox said @30 psi with c16 keep it between 9-12 total if you need more power raise boost dont increase timing he was bending aluminum rods.Usually the first thing to break on the 2.4 with serious detonation is the oil pump then it just escalates from there.Sorry not trying to hijack thread but thought this would be some good info for the dohc guys"

Also heres a good formula for dynamic compression ratio
the formula is: (actual boost/14.7)+1 xCR).
so right now I'm running(15/14.7)+1x9.0), which =~18.2:1cr

It's not an 8V, you're right. Without the background story you wouldn't quite understand where I was coming from with that. JT is fairly sure that when using FAST on his 8V setup that he was only running I believe it was 10, or 12, or something like that advance when it was running so strong. I see that as far lower than what even a very good 8V head would require to make the power he did. A pent roof head is surely different, but too little is just as shitty as too much in my opinion.

On Kevin's information, everyone has their own theory when tuning a car. You can do whatever you want, nobody can rightfully say that their way is the only way.

Having said that, we've ran 26 psi on one of Bill's 20G kits on straight pump gas on a stock motor SRT4. Where was that 15 psi max again? The car was making decent power for a bolt on setup, but 15 psi is nothing.

A Honda I tuned is on a 9.0:1 CP piston bottom end, stock GSR head (similar to an SRT4 if it helps) with a very nice array of supporting modifications, EQ tubular header, big plenum intake, GT3076R, AEM, 1000cc injectors, etc. That car made 426 whp and 289 wtq at 18 psi, with 18* timing. Pump 93 octane, zero issues. A boosted H22 I tuned made 406 whp 305 wtq at only 15 psi on a 72mm ITS, with around 17* advance.

DCR has a good point too. With big turbo cars, rasing the boost is much easier to make power than timing, and generally safer. How many times has he made successful passes with that car though? I hate to put it that way, but really, for someone that preaches a safe tune what kept happening that wouldn't allow him to make a pass consistantly? But damn did it rip when it held together!!

The most knowledgable and best tuner I've seen work does a friends Eclipse, on straight pump gas the car can run 20-21 psi using a 35R on a 2.3 bottom end, 8.5:1 compression. It goes 11.38 @ 124 mph in a 3300 lb, leather lined luxury machine.

[Speedeuphoria]

JT is fairly sure that when using FAST on his 8V setup that he was only running I believe it was 10, or 12, or something like that advance when it was running so strong. I see that as far lower than what even a very good 8V head would require to make the power he did.

Yes and I as well as most would agree with that being very low timing for an 8valve

A pent roof head is surely different, but too little is just as shitty as too much in my opinion.

Yes, you have to work w/ what fuel you have meaning add timing or boost till you get knock, then watch the EGT's till they get too high for your liking and find a happy medium


Having said that, we've ran 26 psi on one of Bill's 20G kits on straight pump gas on a stock motor SRT4. Where was that 15 psi max again?
Did you read exactly what was written, w/ higher compression than the stock SRT4 this was the suggestion. I also would believe that this is a conservative estimate.

A Honda I tuned is on a 9.0:1 CP piston bottom end, stock GSR head (similar to an SRT4 if it helps) with a very nice array of supporting modifications, EQ tubular header, big plenum intake, GT3076R, AEM, 1000cc injectors, etc. That car made 426 whp and 289 wtq at 18 psi, with 18* timing. Pump 93 octane, zero issues. A boosted H22 I tuned made 406 whp 305 wtq at only 15 psi on a 72mm ITS, with around 17* advance.

DCR has a good point too. With big turbo cars, rasing the boost is much easier to make power than timing, and generally safer. How many times has he made successful passes with that car though? I hate to put it that way, but really, for someone that preaches a safe tune what kept happening that wouldn't allow him to make a pass consistantly? But damn did it rip when it held together!!

The most knowledgable and best tuner I've seen work does a friends Eclipse, on straight pump gas the car can run 20-21 psi using a 35R on a 2.3 bottom end, 8.5:1 compression. It goes 11.38 @ 124 mph in a 3300 lb, leather lined luxury machine.

You also have to know that Kevins car is ~9.0:1 CR like mine, not 8.6:1CR as he thought when posting that info as Bob Stockum's web page has incorrect info on the pistons(where kevin got them from). Also the calculations that I have show there more like 8.9:1 rather than 8.8:1 as advertised.

You should also know he had a log header at that point which has an effect on reversion and knock. Also has a medium IC that is hard pressed for fresh air due to the Shelby Daytona front bumper. There are also other varibles that none can account for like sharpe edges in the combustion area(like the valve pockets in the piston) and air temps that can lead to knock sooner then others.

I'm not butting heads w/ you Aaron as I know you have experience, just sharing some info w/ ya'll on this application.

That being said I used Kevins input for a base for my timing map. Now that he has a tubular mani and more air moving over the IC he may very well have a better knock threshold? Also I have yet to thouroghly test my setups knock threshold. I have a free flowing mani(may not be the best) and sanded the sharpe edges on my pistons before install so I hope that I can run more timing before knock becomes present. I also understood this when setting it up, Even w/ the 245 DR's 15psi is plenty to get around on. I also planed to have W/I and use better gas when uping the boost. This was to make more power possible as ~30psi is getting close to the max of the turbo(and fueling for that matter on my setup) and I can provide enough octane when needed to acomplish this, also I dont really care to push it higher. I could have went w/ a 7.5CR like Ondonti and ran on pump all day and added W/I when I wanted to hit 30psi, but I chose to hopefully make a little more HP when the turbo is close to maxed out. Kinda like a bb turbo, I dont see the point in my setup, its FWD, I have plenty of spool w/ the CR and auto and it doesnt drop when shifting so whats the point?We shall see.

Another note that Kevin shared w/ me was that on his 8valve when switching to auto from 5spd he had to reduce timing that was fine on the 5spd because it would detonate w/ the auto. Have you had any experience w/ this as it was new to me??

[8valves]

Another note that Kevin shared w/ me was that on his 8valve when switching to auto from 5spd he had to reduce timing that was fine on the 5spd because it would detonate w/ the auto. Have you had any experience w/ this as it was new to me??

No, zero experience on this. I've only tuned one auto car, a 596 cid brodix head'd 10-71 BDS running on FAST XFI in a backhalfed Nova using a brake'd 'glide and some gargantuan meats! It's always been an auto though, never switched back and forth. It's a good street car It's up out of Port Huron... don't mess around with him!

Everyone's setup is going to be different. Cams are something nobody has mentioned that have a huge impact on all of this.

I'm not usually a big fan of the "see when it knocks and back it off" mentality. Like I said, everyone has their own methods to this stuff, and nobody has the only right way. I prefer to use plugs as a big time indicator. Old school, but it doesn't lie to you.

[BadAssPerformance]

JT is fairly sure that when using FAST on his 8V setup that he was only running I believe it was 10, or 12, or something like that advance when it was running so strong. I see that as far lower than what even a very good 8V head would require to make the power he did.

Yes and I as well as most would agree with that being very low timing for an 8valve

12° at 6000 rpm 25psi 10° abobe that... I have asked FAST and they said that what is in the table is what you get. I have data logs to prove it too.

[8valves]

12° at 6000 rpm 25psi 10° abobe that... I have asked FAST and they said that what is in the table is what you get. I have data logs to prove it too.

I don't doubt you! I just still think it's unbelievable that the car would make the power you obivously were with so little timing. What were your EGT's like?

You get what's in the table, just so long as you don't have a modifier affecting it, and your dist. is put in at 0*.

If you install the dist. at 12 like normal, and don't tell it that... it has no idea. I believe there is a setup tab in there that will allow you to sync both together to be sure.

[Aries_Turbo]

ok back to my question.... you guys with 2.4L's.... should i ramp back those timing values in the image that i posted as the boost goes up for my friends 2.4 that he is going to be building?

its going to be a stock SRT internal motor with prolly a 50trim t04e. looking for 350-400whp.

Brian

[t3rse]

I don't doubt you! I just still think it's unbelievable that the car would make the power you obivously were with so little timing. What were your EGT's like?

You get what's in the table, just so long as you don't have a modifier affecting it, and your dist. is put in at 0*.

If you install the dist. at 12 like normal, and don't tell it that... it has no idea. I believe there is a setup tab in there that will allow you to sync both together to be sure.

i don't know if fast uses the hep, but you can pretty much put the dist wherever and it won't affect timing. I know that sounds weird but think about it. if you are still using the dist for spark distribution but the coil is fired via edis, then as long as the spark jumps from the button to the wire distributor placement won't affect timing.

[8valves]

i don't know if fast uses the hep, but you can pretty much put the dist wherever and it won't affect timing. I know that sounds weird but think about it. if you are still using the dist for spark distribution but the coil is fired via edis, then as long as the spark jumps from the button to the wire distributor placement won't affect timing.

I don't know what he used to use for a signal, but I know that we had a Caprice used as a training aid, if the distributor got touched everything was out of wack.

Also, Honda's setup on AEM need their distributor sync'd in to what AEM says base is, and make sure that the dist. hits base timing the same, otherwise it's off again.

If the coil fired off to send the spark, but the button was near cyl 2 and needed to be near cyl 1, now what? I'm being serious here, I'm not sure how that would work out. That was my reasoning as to why they needed to be sync'd in. Thougths?

[8valves]

ok back to my question.... you guys with 2.4L's.... should i ramp back those timing values in the image that i posted as the boost goes up for my friends 2.4 that he is going to be building?

its going to be a stock SRT internal motor with prolly a 50trim t04e. looking for 350-400whp.

Brian

I would. Most pump gas cars with pent roofs will make plenty of power safely at around 17-18* advance at WOT at full boost, 20 psi or under. If you're going higher on pump gas without any aids, then you might consider backing it off a bit as you go up. You'll have to make that judgment call based on how the car is reacting to it.

[overlordsshadow]

Looks great man, looks damn fast too.

[Aries_Turbo]

I would. Most pump gas cars with pent roofs will make plenty of power safely at around 17-18* advance at WOT at full boost, 20 psi or under. If you're going higher on pump gas without any aids, then you might consider backing it off a bit as you go up. You'll have to make that judgment call based on how the car is reacting to it.

ok, ill modify that table accordingly. i havent tuned a car with a pentroof head yet, just my 8v stuff so ill keep that in mind. thanks

Brian

[t3rse]

I don't know what he used to use for a signal, but I know that we had a Caprice used as a training aid, if the distributor got touched everything was out of wack.

Also, Honda's setup on AEM need their distributor sync'd in to what AEM says base is, and make sure that the dist. hits base timing the same, otherwise it's off again.

If the coil fired off to send the spark, but the button was near cyl 2 and needed to be near cyl 1, now what? I'm being serious here, I'm not sure how that would work out. That was my reasoning as to why they needed to be sync'd in. Thougths?

you have to get it relatively close, but on a 4 cylinder there is 90* between leads, so there is a little less than 45* of error to still achieve a path of least resistence. on my 8v with SDS, i always eyeballed it, after i had done some experimenting and found that moving the cap didn't do anything unless i turned it more than 20* off either way.

[SebringLX]

I have the actual stock SRT-4 timing table, not sure how much different it is from the one AEM uses. I'll post it up when I'm home later tonight. I also have the Stage 2 SRT-4 timing table, as well as stock and Stage 1 PT Cruiser automatic tables. It's nice to have access to over 400 parameters in the NGC PCMs.

[Aries_Turbo]

cool, can you post them all?

Brian

[BadAssPerformance]

I don't doubt you! I just still think it's unbelievable that the car would make the power you obivously were with so little timing. What were your EGT's like?

You get what's in the table, just so long as you don't have a modifier affecting it, and your dist. is put in at 0*.

If you install the dist. at 12 like normal, and don't tell it that... it has no idea. I believe there is a setup tab in there that will allow you to sync both together to be sure.

No EGT, just A/F of ~10:1-11:1 depending on the cal, same ~120-123 mph in that range, wonder how much power it could have made with more timing

The FAST setup uses a magnetic crank trigger that the distributor references at like 40°-50° for the trigger and then the distributor is 12° or whatever you set it to in the table and check with the light.

[Pat]

When discussing the ideal advance, doesn't where the engine make it's peak torque come into play? More advance = more cylinder pressure, cylinder pressure = engine torque. If you're engine set up is geared towards 4000-7000 rpm, you'll need less timing than a motor that is set up to sing from 6000-9000 provided they are running the same octane/AF.

Granted, I have no cal tuning experience, but I've always looked at timing as a way to maintain the highest possible cylinder pressure, regardless of VE at a given rpm. In other words, to offset lower VE in an rpm range. If the engine geometry, head, manifolds, turbo, etc are producing high volumetric efficiency at a given rpm range, the need for a ton of advance drops. If the set up is producing a low VE at a given rpm range, adding advance helps offset that by increasing cylinder pressure through when the combustion occurs. That how I can accept the lower timing advance numbers that you usually see with the typical, lower rpm (below 7k), big torque numbered turbo mopar vs a high revving, lower torque Honda.

Am I off the mark in my thinking here?

[8valves]

When discussing the ideal advance, doesn't where the engine make it's peak torque come into play? More advance = more cylinder pressure, cylinder pressure = engine torque. If you're engine set up is geared towards 4000-7000 rpm, you'll need less timing than a motor that is set up to sing from 6000-9000 provided they are running the same octane/AF.

Granted, I have no cal tuning experience, but I've always looked at timing as a way to maintain the highest possible cylinder pressure, regardless of VE at a given rpm. In other words, to offset lower VE in an rpm range. If the engine geometry, head, manifolds, turbo, etc are producing high volumetric efficiency at a given rpm range, the need for a ton of advance drops. If the set up is producing a low VE at a given rpm range, adding advance helps offset that by increasing cylinder pressure through when the combustion occurs. That how I can accept the lower timing advance numbers that you usually see with the typical, lower rpm (below 7k), big torque numbered turbo mopar vs a high revving, lower torque Honda.

Am I off the mark in my thinking here?

It does, and you're right with your thinking. But even with a low rpm, typical TD setup... the VE is junk compared to most. Maybe junk is the wrong word, but it's far from ideal, especially if they're kept in near stock form. On the other hand of that particular point, a bone stock B16, H22, or F20C (among others) Honda engine peaks at over 100% VE in the top revs. They still use decent timing with boost, such as the examples that I have dealt with.

Now to throw a wrench into things, why did the SRT boys decide to use so much advance with the SRT4? I can tell you first hand it's not because they like that method, you should see how little timing the 6.1's run... sheesh! The engine isn't a slouch either, they're pretty strong pieces. Of particular interest is how small the exhaust ports are... unbelievable that anyone makes any power on the stock heads because of it... but they do!

[Pat]

It does, and you're right with your thinking. But even with a low rpm, typical TD setup... the VE is junk compared to most. Maybe junk is the wrong word, but it's far from ideal, especially if they're kept in near stock form. On the other hand of that particular point, a bone stock B16, H22, or F20C (among others) Honda engine peaks at over 100% VE in the top revs. They still use decent timing with boost, such as the examples that I have dealt with.

But, the combustion event takes the same amount of time to complete. At top revs( 8-9k?), even at 100% ve, you need to start the burn earlier to get peak combustion pressure at the same point in the the crank rotation than you would at 4k. You can't make the mixture burn any faster at the same octane and AF ratio. Make sense?

Now to throw a wrench into things, why did the SRT boys decide to use so much advance with the SRT4? I can tell you first hand it's not because they like that method, you should see how little timing the 6.1's run... sheesh! The engine isn't a slouch either, they're pretty strong pieces. Of particular interest is how small the exhaust ports are... unbelievable that anyone makes any power on the stock heads because of it... but they do!

SRT? You've got me there. Maybe because of the ridiculously undersized turbo on there?