4.0 Tuning Exercise Phase 2: Planning for the supercharger

[mmag1982]

After finishing most of the bolt-on performance upgrades the next step for me is initiating a forced induction project for my jeep , here are my thoughts and criteria , please let me know what you think. I appreciate the input of the experienced guys who make excellent projects as I saw recently on this forum.

1. I decided to use a supercharger and not a turbocharger mainly because the jeep has a very tight engine bay, where the exhaust manifold is mount in the worst location ever under the intake manifold. I simply dont have the skills and resources to fabricate a custom manifold to mount a turbo in this very tight area. I was barely able to install a tube header in that area.

2. I am planning to run a boost pressure of 8 psi. Its just an educated guess based on the technical literature I read on the topic, this boost pressure is equivalent to around 1.5 pressure ratio which should be easy to achieve for all supercharger types, and should give me a decent increase in power.


3. I want the installation to be as simple and neat as possible with minimum permanent modifications to the car. I want to direct my focus to the supercharger sizing , thermal efficiency and fuel delivery of the system rather than custom fabrication.


4. I am on a limited budget for the project, around $1,500. most of which should be spent on the fuelling system and the blower itself ( a used one )

5. I need everyone's help here to share their info about which type of supercharger to use in the 4.0 jeep engine ( Roots, twin-screw, centrifugal ).

My personal preference which i know goes against common practice, is to use a centrifugal type simply due to space and simplicity of installation. I am thinking the area where my air filter now sits where I can install some sort of bracket for a pulley that is in the same plane as the power steering pulley.
I know the dis-advantages of the centrifugal being poor low RPM boost but I think if I size it properly I should be getting useful boost as early as 2500-3000rpm. I like the idea of the centrifugal as well because as many technical books say, it allows me to keep the stock location of the throttle body in addition to being compact. Hood clearance is virtually non-existent in the engine bay to the extent that the pcv grommet sticking out of the valve cover makes contact with hood insulation as hood closes!.


6. I am lost in the different brands/ family's of the centrifugal e.g: paxton, vortech, etc. I can read a compressor map and correlate it with my engine flow figures. Just need some help where to look.


7. I dont know if running at 8 psi would need an inter cooler or not: air to air or air to water? is the temperature gain at that boost really that significant? I live in Egypt and ambient temps in summer can reach up to 104 F. However the jeep is running fine now although the intake is sucking very hot under hood air.


8. How can I accurately calculate my engines actual flow rates at various RPM points say 2000, 3000 , 4000 and 5000 rpms?. The generalized data I have is that the 4.0 engine has about 77% VE at the torque peak and 70% at the red line. Follwing this assumption my initial calculations say that the engine has a flowrate of 245 CFM at the redline. any one has more accurate data?

9. For fuelling I am planning initially to use AEM Fuel/Ignition piggyback controller. But I dont know what injector size would be suitable for that kind of boost. My stock injectors are rated at 21 lb/hr with 49psi of fuel pressure. how big should the new injectors be? can 24 lb/hr support it? In addition I dont know how the jeep Manifold Absolute Pressure sensor would react to boost? My initial guess is that it is designed to read vacum to atmospheric only.



Appreciate your thoughts,
by the way , sorry if it sounds naive but I cant find a way to post photos to any thread. I thought I subscribe i can but cant find my country ( Egypt ) in the paypal list :smsoap: any ideas?

 

[wolfpackjeeper]

3.8L blower from a ford. Some of them were a bolt on instead of being part of the intake manifold. This gives you the option to ditch your AC, fab a bracket, and run it of the serp belt.

This is generally what I have my eyes open for when I hit the yard. I would like one to run some boost on my stroker.

 

[mmag1982]

do you have more details on the blower type which model year was it used in etc..

 

[FlexdXJ]

do you have more details on the blower type which model year was it used in etc..

early-mid 90's Thunderbird super coupes had blowers on them.

 

[FunkRider]

Some XR7 Cougars of the same time frame had 3.8 supercharged engines also. I would use an M90 from a series II 3800 aka Grand prix GTP, bonneville SSEi buick GS from mid 90's. They are cheap and are more efficient vs the earlier generation of Eaton blower used on the fords. Air to water intercoolers are very available these days too and I would very much suggest working one into your build. You can also get the GM M90's REALLY cheap when they rattle at idle because people think they are junk when they rattle but they require a new SC coupler in the nose drive.

 

[Talyn]

Use the most efficient SC you can afford. Twin screw would be the best, but there have been improvements in newer systems. The centrifugal chargers will work more like a turbo where you have little boost at lower RPMs and it buillds as boost increases. Somewhat like turbo lag. With Positive displacement there is more boost at lower RPMs. Although for what you are trying to do you may want to place more weight on how it mounts, if you can mount it, if the input and out put are in the correct places, and whether it has its own oil system or if it uses engine oil.

Use an intercooler if possible. Its never a bad idea.

That rattle isn't always the coupler in the nose drive going bad. Bad bearings start out as a rattle then progress to a knock. I have seen 3 eaton units in the past year that have had a rattle and it wasn't from the coupler. So take in consideration that you may need a rebuild on a used sc.

AEM FIC is probably the best unit out there for a piggy back. For injectors I would say 24 lbs, but you can go a little larger if you need to as you can tune it with the AEM. You will also need a wideband O2 gauge. I prefer the types with data logging.

 

[mmag1982]

Thanks talyn,
what about the stock MAP sensor? how will it react to the intake manifold under +ve pressure instead of vacum to atmospheric which is its normal operating range? or do units like the AEM FIC have their own MAP sensor?


one naive question, how will intake manifold vacum operated devices like the brake booster,pcv system and evap canister react to the manifold being under boost? do the hoses need to be relocated?

 

[mmag1982]

Thanks talyn,
what about the stock MAP sensor? how will it react to the intake manifold under +ve pressure instead of vacum to atmospheric which is its normal operating range? or do units like the AEM FIC have their own MAP sensor?


one naive question, how will intake manifold vacum operated devices like the brake booster,pcv system and evap canister react to the manifold being under boost? do the hoses need to be relocated?

 

[gradon]

The AEM F/IC and some of the Split Second FTC1s and PSC1s(my -002 does) have built-in 2 or 2.5 bar maps so that they can measure boost.

 

[mmag1982]

anyone knows the part number of the AEM FIC designed for the 01 xj 4.0?

their website only mentions a universal FIC/6 for 6 cylinder cars. The extension harness is listed by model but cant find a specific model for the computer itself.

to guys with software tuning experience here:

lets say I wire the AEM FIC correctly and start the car for the 1st time, how does the FIC acquire the baseline OEM map?

My thinking is that since I already have the AEM wideband AFR gauge , I have to see the stock map 1st, in order to see where I need to adjust the injector pulse duration.

for example ,from my close observation to the AFR so far, only the lower half of the RPM needs adjustment . Following this approach adjustment under boost should be easy

 

[gradon]

With the maps all set to zero(as they come new or as your used unit is reset), what goes into the FIC is what comes out. 30-1913 is the model you want to look for--it is universal. 30-2984 is the harness you want.

 

[Talyn]

FYI the 1913 isn't universal. The fuel injection drivers are different for Jeep/Dodge vehicles. The universal is 1910, which you don't want.

 

[JJacobs]

So you're thinking of using a centrifugal blower, AEM electronics and getting it running for $1500? You guys must have super cheap used parts over there.

 

[gradon]

Let me rephrase: the 30-1913 probably fits 50+ Mopar models over 10+ years(universal enough--my 96 XJ up to an 05 SRT4, so any 4-6 cylinder they made in those years). Also, the 1913 supercedes the 1910--they just had to work extra hard to make the 1913 not set off the Chrysler CELS for interrupting the injector duty cycles like the 1910 did, so I willing to bet that the 1913 can control all 1910 apps.

 

[mmag1982]

So you're thinking of using a centrifugal blower, AEM electronics and getting it running for $1500? You guys must have super cheap used parts over there.

I am planning to source the centrifugal if I decide to use it as a used item, of course no way i'll b able to afford it new.

So far matching my flow calculations to compressor maps, the 4.0 engine should need around 370-400 CFM at 5000RPM for 8 psi of boost. The best compressor to match this is the Vortech V5 D, G or F trim. It puts it right at the center of the efficieny map of 75% for a pressure ration of 1.5

I can see from my research far that it was installed in some toyota cars under the TRD name, but cant find which model yet. anyone has any details about this blower in toyotas?


As for the Eaton M90 assessment, given its dimensions of over 16 inches long, I cant seem to find a place for it in the engine bay in addition to an air to water after cooler. Its just too big. I made a mock up and tried to seat it where the air filter is , the pulley would be somewhere next to the OEM tension-er pulley, but there wont be any room for the throttle body which will fit at the blowers rear end.

as for the rough cost breakdown:

- around 550$ for the AEM FIC + harness
- used blower for 300$
-air to water aftercooler 150$
- blow off / anti sure valve ( dont know yet )
- rest of the system like the air to water heat, ex-changer, electric water
- 28 to 30 lb injectors 200$ ( rough calculation )
pump , pulley should be easily sourced from used parts wholesalers. Maybe it will cross the 2000$ mark

 

[theoriginalscion]

I'd shoot for the 30 lb injectors. I'm only running 4.5 to 5 lbs of boost.the stock 21lbs were able to fuel at those boost levels. Id see a max duty cycle about 91,92% at full load. Currently have some 42's,that are way to big. idlle is like 1.5-2% duty cycle.barly get to 40% at 5lbs boost.

 

[Talyn]

30 lb injectors will probably be too large.. i would try 24-25 lbs

 

[Boostwerks.com]

30 lb injectors will probably be too large.. i would try 24-25 lbs

Bah, 30's would be fine. I have 42lber's and they run fine with a compensated pulse width. The only thing I've noticed is they take a little longer to "wake up" the motor in cold weather.

On a side note, Injector Dynamics has been able to idle their 180lb injectors on a small 2.0L motor. Impressive considering that the injector is large enough to hydrolock the motor during start up if the wrong pulse width is entered

 

[casual]

Air to water intercooler? Why?
In all honesty I believe your better off with a plain jane air to air! Air to waters WILL get heat soaked far sooner & take 10x as long to cool off. Essentially you'll heat the water which is what cools the air..once its hot, how will it cool the air effectively? Where will you mount it, since most air to water setups are mounted in the engine bay which is already prone to excessive heat...
Most hardcore drag racers, as in track only use a water to air setup because the water will cool the incoming better, but agian the only race for 10 seconds. As a daily vehicle that will see traffic & alot of street use, I feel it'll be pointless once the waters hot. Mount a air to air and you'll be more than ok and it should cost less to.
I come from supras and turbo lexus IS300's that are making 500whp-900whp, So I know a few things here. I just rebuilt my buddies Is300 and swapped in a v161 6speed supra transmission. Hes making 701whp right now!
I actually have a full AEM setup I can sell you With just about every sensor you'll ever need and want! Downside is thats it the AEM EMS V2 with go for around 1300-2200 depending on accesories. Big plus is this units never been used or unboxed, still sealed up with the tape & box it was sent in


Anyway I say a cheap Godspeed intercooler from ebay which will suit you just fine. They run from $50-300. Many guys run them, Chad is making 701whp and using a godspeed intercooler & we live in cali and see 100* regularly in the summer lol. No issues at all and if you think you are having issues, you can make a intercooler mister for pennies.
I also say run 18lb injectors and meth injection. The 18lbs won't need to be compensated for since 18lbs is stock & the meth will make up for any fuel needed! You could also bump the fuel pressure up a few degrees which won't hurt a thing..You won't have to spend cash on injectors this way & won't really need to "tune" for them. You can make minor adjustments and be good to go. If you don't feel safe then run the 24lbs. Meth will cool your intake charge & raise the effective octane rating, thus you'll fight of detenation & can effectively run a more aggressive tune! Think of it like race gas in a way...Also with meth injection it steam cleans your motor when it sprays..This has been proven and as long as your somewhat compentant you'll never have an issue!!! With meth injection you may not even need a intercooler because the meth with cool your intake charge considerably...and kits are so simple now, they sell for $150-500 and you can use your windshield fluid resivoir for the meth. They work off of boost pressure. The higher the pressure the more it'll spray, you just need to find the right nozzle size. And again Chads running meth on his car, he actually buys rubbing alcohol from the dollar store and pours it right into his windshield fluid resivior, no mixture needed since its 46% alcy/54% water. Its perfect and runs great and has been tried & trued.
His cold side piping is so cold, it actually feels like it was in the fridge/freezer. His hot side piping is cool enough to touch without fearing a burn now as well. Its done wonders on his car, he went from 632whp on 91oct @ 17psi to 701whp on 91oct. & meth @19psi...2psi gain and 70whp? His tune is far more aggressive and its as safe as can be! He loves it..
To give you a rough idea, a stock is300 with a manual transmission puts down 175-190whp. If you do the math Chad's making about 28whp per PSI which is damn decent..yes yes I know its not just the PSI making the power before some smart guy trys to correct me.
Just an estimate to give you an idea, this is in no way accurate but I bet you come close to these numbers if its done right. Theres videos of stock Xj's putting down 90-110whp And since you have your bolt ons done, I'd assume you have 100-105whp+- . So to be consertative and since this is supercharging not turbocharging. I'd just guess and say 10-12whp per PSI. So if you were at 105whp now, you would be around 200whp with 8psi..Obviously this isn't 100% accurate as different things come into play and there are many variables, but just to put an idea on the table...
I say get you a nice 3" mandrel bent downpipe into a 2.5" catback as well. Dino has claim he had gains after his 3" downpipe was made for his 4.6L stroker..it'll deffinetly be worth it. And I don't want to hear no back pressure crap lol. Your going forced induction...you don't want restrictions lol.


I have stuff here and there that you need and what not. Intercooler piping & 3 million couplers lol. 2 BOV's. 1 Tail & 1 HKS..yes a real HKS. I have a few wastegates. I have the AEM EM V2 that was never used, bought it but never installed..We went with Pro EFI instead.
ask if you have questions, I'm fairly knowledgeable when it comes to forced induction.

 

[casual]

AEM FIC is probably the best unit out there for a piggy back. For injectors I would say 24 lbs, but you can go a little larger if you need to as you can tune it with the AEM. You will also need a wideband O2 gauge. I prefer the types with data logging.

And I hate to say this but FiC is way out dated. GReddy EMU is far superior. You can raise the limiter with EMU & you can't with FIC, advance or retard the timing with EMU..while FIC can only retard it. You can adjust fuel imputs at closer increments with EMU, I believe every 250rpm instead of 500rpm like FIC. Also, at least around me, most tuners won't even touch FIC. Most suggest you use EMU because its easier to tune with....
Idk about you but how many tuners are there in Egypt?

Only thing FIC really has on EMU is that is can Skew the 02 sensor and basically turn off the cell which I saw someone mention in this thread I thought..EMU has my vote because I've seen and handled & used both. It easier and far better to tune with. Now if you want to talk stand alones..I've used AEM EMS & Pro EFi. Pro Efi being the better because of its options but EMS for simplicity. Pro EFI is a b*tch to get working because of all it options. EMS was always short and simple.