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(Q/A thread) SRT-4 Performance Modifications and Upgrade Paths

59K views 193 replies 54 participants last post by  NorthNJSRT4 
#1 · (Edited)
#45 ·
If you're trying to use an FM or S2 WGA on a stock or Stage 1 PCM with the 93tune it's not going to work right out of the box. The 93tune on a stock or S1 PCM assumes that you're using a stock WGA so the wastegate duty cycle is scaled for that WGA alone and PCM WGDC% learning is disabled. But there's a trick to get it to learn the correct WGDC% to operate an FM or S2.

1.) Boost leak test the system, tbolt hose clamp and ziptie all the lines making SURE everything is tight. If you don't have a boost leak tester you will need one to complete this step, just tightening things up isn't enough to be positive there are no leaks.
2.) Run a single vacuum line from the turbo housing directly to the WGA then set the arm so that it boosts to 8-9psi. Keep tweaking the arm until it's good.
3.) Hook the vacuum lines back up on PCM control as stock through the WG solenoid.
4.) Load the factory stock or Stage 1 tune back on the PCM, start the engine at least once.
5.) Reset the PCM by pulling the negative lead off the battery for a minute.
6.) Drive the car around doing some WOT pulls for a while until the boost levels stabilize and become predictable (this is the learning process).
7.) Load the 93tune without resetting the battery.
8.) With the handheld, set up your desired boost level to what you want to hit in 3rd or 4th gear, set up your AFR to your target in 3rd or 4th gear, datalog for knock (adding fuel or pulling timing as needed to make sure ST knock never goes over 1 count).

If you have to reset the battery for any reason, write down your DSP settings and repeat the whole process again from step #4.

If for some reason you just can't get the car's boost level dialed in you can make things easier by getting a rescale tune for the FM or S2 WGA by PMing "Turbo666".
 
#50 · (Edited)
An AGP or Kinetic WGA can't be used on PCM control which is one of the many reasons why they suck with a DSP. Even with a CMR dealer's rescale tune, the lowest possible boost level they can hit is the weight of the spring (usually 15-17psi) so there's no way to eliminate the very undesirable condition that is partial throttle overboost which makes the car ALOT less fun to drive on the street.

They were great when we really didn't have any other way to hit high boost targets (I own a Kinetic and an AGP; loved them for years) but since the DSP came out and we gained full control over the PCM they're pretty much worthless now.
 
#51 ·
Is the AGP FMIC you listed the best thing to get on an all stock setup as far as IC's? The reason I ask is that im trying to do the few things im capable of doing myself upgrade wise before getting into stuf that i dont have the time, skill, money for proper apprenticeship, etc. to do.
Thanks
 
#52 ·
IMO...The AGP Mini is the best direct fit unit available because of it's end tank design and core. Second would be the Spearco stage 1 then, on a budget, the CX Racing direct fit.
 
#55 ·
Correct but you don't get the increased torque output tables (where you get the power increase over stock) or the much more desirable 11.77AFR base point.
 
#58 ·
/Agree

The stock O2 housing is just fine on a stock turbo. Going up to a 3" only gives you a marginal gain over stock and it's a serious pain in the ass to change.



If i buy a mopar cat delete downpipe do i need to buy an o2 housing?
I wouldn't bother with the Mopar one, it's insanely expensive for what amounts to a just a metal tube. If you have that kind of money to spend, a 3" Needswings catless cutout with an electric opener would be alot better for the same money. If you just want a strait 3" catless downpipe, Needswings offers an extremely well made one for 1/3 the price of the Mopar DP.
 
#60 ·
The next installments are coming shortly. They'll cover 'final touch' mods for maxing the stock turbo, drag strip mods to cut your ETs and big wheel stockers for those that want a lil' more out of the stock exhaust mani setup.
 
#62 ·
I actually had a few questions, I was thinking about getting the MPx BFMIC or the AGP direct fit intercooler but cant decide between which one, but reading your thread it seems that the AGP may be a better solutoin for me, and all my mods are in my sig. Also I dont know if i should get a DSP or not because my buddy has a guy who can custom tune my car and he said he needs a DSP in order to do it. Im mainly getting a custom tune because i cant use the 93 with my AGP wastegate. But do you think I should get the DSP to custom tune it? Do you think it would work? Or should I just take it somewhere to get a custom tune? I was thinking about taking it to turbo666 but its quite a drive from where i am. My goal is o hold atleast 18psi.
Thanks!
 
#63 ·
You wont be able to hold 18psi to redline on factory turbo. You may however spike higher than that but it will fall down to around 15psi due to how small the turbo housing is. If I were you, I would get an OEM wg and sell the agp. Upload the 93tune and call it a day. You will be spiking around 20 psi and you will have better driveability.
 
#64 ·
well i dont really see why everyone hates on the agp wastegate haha but if i was going to sell it id rather get a stage 2 wastegate not stock, but i dont know where to get one, any ideas? and id be able to use the 93 on that one then right?
 
#65 ·
Im trying to do the same thing i have been looking on ebay and craigslist every day and no luck finding a stage 2 wastegate. There was one a couple weeks ago but i passed thinking that my agp was better. Im not going to lie though i like the way it performs . It feels like it holds boost better then stock.
 
#66 ·
Ya i like my agp a lot too, ive just beend reading up on both and honestly i think im going to keep it because as long as you learn to drive it right and not PTB youll be fine, so i think im just going to get the DSP and get a custom tune, i was also wondering when i get the DSP for a custom tune will i need the 3 Bar/TIP pacakage with it? or the update kit? or just the DSP itsself?
 
#67 ·
I Mite just do the same . I have to research some more and find out how to drive it with my agp .
 
#71 ·
alright thanks North, my goal is to max out the stock turbo right now, and i would like to run as much boost as i can, which wastegate would be best for me do you think in order to max out the stock turbo?
 
#73 ·
I maxed out the stock turbo on the stock WGA (~24psi with water/meth injection and 26psi on E85). With the custom tune you'll need in the end to max out the stock turbo it really doesn't matter if you choose the stock, S2 or FM WGA. However, that being said, the FM with it's 7lb spring is the easiest for a CMR dealer like Turbo666 to tune for and has the quickest return after a shift without sacrificing any partial throttle usage (like the AGP does).
 
#72 ·
because right now im leaning towards getting the FM wastegate and might sell the AGP then
 
#75 · (Edited)
They both have their advantages and disadvantages. E85 makes about 5% more power than pump+meth but you lose around 30% range per tank. Depending on where you live it can save you money over 93 octane but by me it's only $0.10 cheaper so it actually costs me more per mile to run. Areas like the midwest that have it really cheap can save money. People that live on the East Coast that can't get E85 locally (like when I lived in NJ) only have the option of running meth. The downside is having to keep the meth tank full, mixing it and storing it but on track days with a couple gallons of C16 spraying straight water from the meth tank it pisses all over E85's power potential.

Personally, I have my car setup to run either. It's just a matter of what I plan on doing. Daily driving is pump+meth 'cause it's cheaper for me (if the price of E85 dropped in Atlanta I'd run it all the time). Spirited driving on the back roads and deserted highways is E85. Track and dyno days are c16 or c23+water for the biggest numbers possible.
 
#76 ·
Thanks for all the help North and ya i think im going to be getting the FM wastegate soon, thanks again!
 
#77 · (Edited)
This question has most likely been beat up. What's the differences from dsp/sct
I have a sct that im useing for my build. Is it sufficient or get a dsp.
The sct has a pre loaded tune for a ptb 5557.
 
#78 · (Edited)
This question has most likely been beat up. What's the differences from dsp/sct
I have a sct that im useing for my build. Is it sufficient or get a dsp.
The DSP can datalog the PCM, the SCT can not.

There are more 3rd party DSP tuners than SCT tuners for this platform.

The DSP allows you to make quick changes to any tune via the handheld in 1K RPM increments, the SCT doesn't allow you to make any changes.

The SCT just requires the relatively inexpensive PRP software to be able to fully tune your car yourself (single license), the DSP requires the VERY expensive CMR software to tune as many cars as you like.

The SCT can fully rewrite the PCM to change it into any Mopar Staged PCM you want, the DSP can only write to a portion of the PCM to change settings of the tune only.


They're both great devices. I'd say SCT PRP is for someone with extensive knowledge and access to a dyno (that will also be using a DSP for datalogging purposes) while the DSP is for the casual user that will mostly be using email\dyno tunes provided for them by a 3rd party.


The sct has a pre loaded tune for a ptb 5557.
The SCT doesn't come with any tunes for a non-stock turbo car so I assume you mean an SCT with a tune from someone like AGP. Their tunes are known to be very conservative which means you'll be locked into however the tune is setup (unable to make any changes) unless you buy PRP and learn how to use it or get yet another tune from someone else to really push the turbo. If you're not very knowledgeable about tuning cars and you are talking about getting a kit from AGP, I suggest asking for a DSP instead of the SCT (which they can do).
 
#80 ·
If you're happy with it and don't need to make any changes then you're set (remember you can always ask AGP for changes). Otherwise you can keep the SCT, get a DSP, marry the DSP to the SCT tune and make broad changes to the tune or sell the SCT, get the DSP from AGP and get their DSP tune for the 5557.

Either way the DSP is nice to have just to be able to run datalogs and see what's going on under the hood.
 
#82 ·
On a stock or S3 turbo, no.
On a big turbo, the best thing to run is the N2MB Racing BoostBox so you get full control over an external wastegate and boost-by-gear (and\or RPM).
 
#86 ·
Ok so I gotta a ? About what's mods I should nxt my mods are
3" b&b exhaust
Dsp on 93 tune
K&n typhoon intake
Boomba fuel rail
O5 stock injectors
Xs intercooler
Fuel reg
Steal return line
Wally 255
Stock wga
Hard pipes with hks
Have meth kit but haunt had time to put it in:(

I have spark plugs wires etc but my ? Is what should my nxt mods be I'm thinking 3 bar map 750 injectors and kinda want a elec. Cutout what u guys think I wana eventually get a 500whp car but I'm taking steps to eventually get there
 
#87 ·
3 BAR MAP and TIP and a rescale tune for them. I'd go with Duster360's 888cc injectors and the free tune that comes with them over a set of 750s (which won't be enough for 500whp). If you plan on ever running E85 I'd go for at least 1100's. At that point you can drop in a big turbo with the mods you already have and get a full tune. If you don't have a 3" downpipe the Needswings catless ecutout is nice. You'd just have to chop off the reducer to mate it to your current 3" exhaust.
 
#89 ·
With a DSP you can store a number of tunes and change them as need be. I run an E85 tune most of the time, a race gas tune for the track and a 3rd for pump gas when I'm away from home (when there's no E85 available).
 
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