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Discussion Starter · #1 ·
Been a a lurker on this site for many years and never really post because I don’t have a bunch to offer in the way of solstice help. I have a 2009 street edition, auto with 35k miles. I’ve decided I want to put a turbo kit on it. I’m between the Werks and RPM. From my reading I would like to stay at/below 300hp at the crank. Keeping boost as low as possible but to get desired results. 10-15 pounds I’m guessing. New too this, I’m use to more cylinders and displacement over turbos.

RPM kit with
Upgraded turbo - K04 with Billet Wheel
Dual core radiator
Upgraded ecotec fuel rail
About $4300

or

Werks
Stage 1 kit
Dual core radiator
About $5100

Looking for any feedback.


TIA
 

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So from my experience talking to other people, RPM can be a hit or miss... I have an RPM kit and I had some major issues going through this process. It took me about a year to complete the project. I waited for my kit for about 3 months, I got the first 2 boxes in 2 months and waited for 3d for another month. I got excuses that the box got lost at UPS.
I had components missing in the kit, i had a fuel system upgraded that had a wrong fuel rail that would not fit on my car. I had missing bolts, nuts, brackets, and fittings... Some of it i ended up buying elsewhere because getting email responses took several days and weeks to get little pieces shipped... When it was all put together we tried to remote tune it for several months, the car was not running right, I could only give it 50% throttle or it would backfire and the engine would choke...
I ended up finding a performance shop and spent an additional $900 to have the tune fixed on a dyno to make it run right.
I could not get a refund for the fuel kit that I returned and the whole thing was a mess)))

Now Martin mentioned at some point that he was going through some personal issues, i was trying to be understanding as much as I could, but it was beyond reasonable and my story is not the only one...

Now had I known more about the turbos, I would also not pick this kit because of the components it used, but this may not be the case for you.
I had phone conversations and email exchanges with Martin explaining what my power goals were and he did not mention once about the capabilities of their kit under different settings. I know for sure that he new about the downsides and they also had bigger turbo options, but he just sold me whatever...

You need to have a clear understanding of what your power goals are and what your budget is for required supporting mods.

RPM is the cheapest kit you can get and will work just fine if you do not plan to run more than 10lb of boost on K04 turbo that they ship in the basic kit.
They recommend running that turbo up to 15 psi which will yield about 240whp according to my dyno runs. BTW 10psi vs 15psi is spinning tires vs not spinning tires in 2nd gear)))

The problem with k04 is that it is severely undersized for 2.4 engine. I was running at 15psi. You will see that your boost drops after 3.5k and by the time you are at 5-6k you are back at 7psi.
So if you are fine with 10psi at 3.5k and 7 at redline - go for it, but make sure to upgrade to their big wheel k04 option, it will be a little better at high rpm.

If you are planning to run 12psi+, you need a return-style fuel system, and please make one yourself for 1/3 of the RPM kit cost using actually quality components. I had a return bung welded to my stock fuel rail and saved a bunch of money on a new rail.

I believe they offer bigger turbos these days so if you want more hp than what I mentioned above you need a bigger turbo. Our bottom end can hold up to 320whp i believe.

Also if you chose to run anything more than 10psi, you would need a quality electronic boost controller that can handle boost spikes. k04 gives you instant torque at 2-2.5k RPM and the mechanical boost controller that is shipped with the kit is completely useless.

Be ready to find a different tuner for remote tuning or dyno tuning. I would not trust remote tuning of my car to RPM again.
You would want to invest in an AFR gauge, and get a quality one, AEM is a good choice if you will tune remotely. If you go to a dyno shop, they will install one for you.
Make sure your downpipe contains a hole for it. With RPM it was an option i needed to request.

Now to pwerks.
From talking to Dave to my knowledge they do not instruct you to have a return fuel system with their kits, Please confirm this.
Their kits are expensive but use better quality components. Their WR2 and WR3 kits are using EFR6258 and EFR 6758 turbos respectively, IMO the best turbo you can get for the money. They are shipped with trial WG which you can set up with a spring set to your target boost setting and you won't need any sort of a boost controller and never will have to deal with boost creep or drop issues. I think they have a better intercooler too. WR2 should be able to flow consistent 30-35lb/min of air which will yield 300-350hp of solid power throughout the RPM range.

Also keep in mind that no matter which option you select you will need to upgrade your clutch, as the stock clutch would not be able to handle the torque that you are going to get.
With RPM kit my clutch that only had 16k miles on it could not handle the torque past 3d gear at 2.5-3k rpm

I don't know about their tuning service, but just by looking at the setup, now knowing what I want, I would get pwerks kit instead.

Now add up the options from RPM (big wheel k04, maybe return fuel system, proper Boost controller (AEM true boost)) and compare to PWerks and you are pretty close.

Currently, I purchased their WR3 upgrade on the top of my RPM kit because I'm tired of this stupid little turbo that cant hold boost...
 

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Dave Gilbert at Performance Auto Werks (PAW) still sells turbo kits for the base Solstice 2.4L. Boost on a stage one is held at 6psi. Should give you under 300HP at the crank, but feel really good with the extra torque. HP Tuner kit is highly recommended along with upgraded radiator for extra cooling. Iridium plugs are a must, one level colder than stock.....
 

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Choptop called it on this one.

My dad just installed a 6758 EFR on his base coupe. The engine internals likely won't hold up, therefore he's already planning on having to drop an additional $5-6k in a built engine.

I sold my base years ago for a GXP when I wanted more power.

If you're happy with the power of a base, then keep it with a proud smile.

If you want even a little more power than a base then buy a GXP.
 

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6758 for the win. Also look up Dave at DDM
 

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OK for you folks that don't know this. How much the LE5 engine is able to take all depends on when the vehicle was produced. Check your drivers door jamb there is a sticker there and in the upper right hand corner is going to be month/year. This is the actual month and year the car rolled off the assembly line. If it is after 12/ 07 then you are only going to be able to get 350 bhp (297.5 whp) out of the engine. It is was built before 12/07 then you can push the engine to ~440 bhp (374 whp). This is because 1/2 way through the 07 model year GM changed the connecting rods to ones of lesser quality and strength.



This is what the LE5 would need for airflow at a given RPM if running 15PSI of boost.

The LNF K05 turbo has a maximum airflow of ~32lb/min which converts to 396.43 CFM of dry air at 75°F. Th 32lb/min is a BS number and the turbo is never able to achieve that. I know this because when the stock turbo is pushing 20 PSI of boost on the LNF it falls flat on it's face right around 5600 - 5700 RPMs. The LNF engine at those RPMs at 20psi of boost would be using 305ish CFM of air and that equates to roughly 25lb/min of airflow.

The 0.4 liters is not that far of a displacement difference. It's only a 20 cubic inch difference. or 5 cubic inches per cylinder. The 2.4 running a K04 turbo is going to hit it's limit about 400 -500 RPM sooner then it would on a 2.0. a 7.6% difference in RPM.

Code:
Displacement of engine is     145 Ci
Boost is  15.0 PSI. Pressure ratio is  2.02
Inlet air temp. is 75 degrees Fahrenheit.
Barometric Pressure is 14.696 psi.
Compressor efficiency is 0.65.
Engine volumetric efficiency is 0.93 <--- Yes this is the real VE of the LNF and the LE5, GM did a great job here.
Actual intake manifold temp is 255.88 Fahrenheit.

RPM     CFM
1500     88.26
1600     94.14
1700     100.02
1800     105.91
1900     111.79
2000     117.67
2100     123.56
2200     129.44
2300     135.32
2400     141.21
2500     147.09
2600     152.98
2700     158.86
2800     164.74
2900     170.63
3000     176.51
3100     182.39
3200     188.28
3300     194.16
3400     200.05
3500     205.93
3600     211.81
3700     217.70
3800     223.58
3900     229.46
4000     235.35
4100     241.23
4200     247.11
4300     253.00
4400     258.88
4500     264.77
4600     270.65
4700     276.53
4800     282.42
4900     288.30
5000     294.18
5100     300.07
5200     305.95 <--- K04  really taps out at.
5300     311.84
5400     317.72
5500     323.60
5600     329.49
5700     335.37
5800     341.25
5900     347.14
6000     353.02
6100     358.90
6200     364.79
6300     370.67
6400     376.56
6500     382.44
6600     388.32
6700     394.21 <--- K04 tapped out according to spec
6800     400.09
The EFR6758 taps out at 50lb/min of air flow, that's 619.42 CFM. in order to get to 440 bhp the engine is going to need 545 CFM of air and to hit 350 bhp the engine is going to need 433.6 CFM of air. This equates to 40 psi of boost for an early production (440bhp) and 22 psi of boost for a late production (350bhp). This is with the target HP output at 6500 RPM.

The EFR6258 is a perfect match for an early production 2.4 and for a late production and the K04 will do well on the late production. Going anything larger then the 6258 for an early production is going to be wasteful as you will not be able to use the additional airflow without grenading the engine and using anything other then the K04 on the late production is not going to give you anything more.

I hope this clears up what turbo should be used on what variant of the LE5 engine. It explains what turbo is going to be the best using raw math. Now there are other things that will come into play like spooling time, that is a different topic all in it's own. This is just raw power and airflow numbers and and a turbo is able to put out in terms of airflow.

As a side note, some information about the LNF

Just to let folks know the LNF is a better built engine then the European version which is the LDU even tho the LDU has a stronger block the internals are only good to 350HP. The LNF both the internals and the block are rated in the same 475 to 500ish HP area. If you want more then 500 HP then get an LDU and build it using all good quality internals and you will be able to get there. Upgrading the internals on the LNF may or may not get you to over 500hp before the block gives out.


Forgot to mention the optimal boost numbers. 40 psi of boost for the 6258 on the early production and 11 psi of boost for the K04 on the late production. That will get you to 440bhp for the early production and to about 280hp for the late production. The maximum HP rating on the late production is not clear, I have seen 300 to 350 hp statements made hence the reason why I said the K04 would do fine for it. This also falls right into line with what RPM says to run the boost level at on their turbo kit. the 11psi is going to max out the turbo's airflow at 6000 - 6500 RPM's
 
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If you want a long term science project, then modify the factory power setup significantly and spend months to years getting it to run properly. Get a GXP and just drive it.

Or take the car to PAW and let them do the work including the tune.

Every club member that boosted a 2.4 had long term issues. With the hardware or with the tune or both.

It took me years to get my non-boosted LS conversion to work properly as a daily driver.
 

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in conclusion, sell your 2.4 and buy a GXP. Your mental and physical health will thank you.
Edit: Sorry for being flip in the above post. The reason I question adding a turbo to the 2.4 isn't about the hardware as much as it's about reading post from folks who are unhappy with the tune aspect of the job throughout the years.

There just doesn't seem to be any consistency around 2.4 turbo tunes due to different turbo kits, but more importantly, different people performing the tunes for them. The "different people" may be the crux of the issue because so much depends on a person's skill level & experience (or lack thereof) around tuning the 2.4 for a turbo application, and how that part of the job impacts the final outcome.

I'm not saying that the hardware isn't of concern, but again if you know you can trust your tuner then you'd think they would have the experience to navigate the different 2.4 turbo kits, and any modifications already on a car. For example one 2.4 is all OEM, and another already has a CAI, performance exhaust, & HFCC. Now I would think that regardless if you have a stock drivetrain or a modified one, that must impact how a tuner goes about trying to get any application to perform at its highest level, and be run consistently at all times.

Then again, another issue may be the condition of the 2.4 itself. How does adding a turbo to a 2.4 with low miles compare to adding a turbo to one that has high mileage? I'm not sure that even an expert tuner can make a 2.4 turbo kit run perfect if there are some underlying mechanical issues going on with the engine.
 

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The single largest hurdle when boosting a 2.4 is the ECM doesn't control the boost. It is either a mechanical adjustment or a standalone electronic controller. Basically the ECM needs to react to what is going on with the turbo and the ECMs in the Solstice are not exactly speed demons. It's not able to respond fast enough to changes that are taking place and I believe that is where a lot of the issues stem from. Trying to tune around them is hard to do. What that means is the tables have to be manipulated in such a manner so that it compensates for the processing lag of the ECM. The boost being controlled by the ECM puts the ECM in control where as with the 2.4 the ECM isn't in control it's just there for the ride and has to react in real time which unfortunately to say it's not the best at doing.
 
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Very good and honest discussions.
I for one appreciate the candor...

I am still going to make the plunge and install a PAW turbo kit with HP Tuners software. I'm only at a stage one kit, only have 4k miles, and have the stronger engine internals, and hopefully won't have major issues. I know iridium plugs, one stage colder than OEM, help with pre-ignition issues. Just wondering what specific issues have occurred in the past? Fuel delivery? Mass airflow? Spark advance control?
Air, fuel, spark are the basic knobs to control....Any one know what were some major symptoms and how far were folks reaching for power?

My conversion didn't happen last winter, hopefully this upcoming. I took the car back from the shop a few weeks ago because the weather is nice and we want to cruise!!
 

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Discussion Starter · #16 ·
Lou O. I agree, great discussion. I have a later motor so I know I shouldn't go above 300hp. I know getting a GXP is the smarter easier option. I've had my car for 11 years, I know its history and I like the looks of street edition. I'm not in a hurry to go this or even sold on it. I have a great mechanic and know he would do fine installing. Its the tune that concerns me in the process. That seems to be the downfall in most installs. I regret not picking up a super charger kit when there were out there. They seem to be a bit easier to get dialed in. PAW is close enough to me to drive to and may be the way I go. Maybe :)
 

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Only problem with PAW right now is he is booked solid thru 2023 and not taking any new reservations . I agree with you on the blower, but they are rare as hen's teeth!
 
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