Topic: Got boost?

[tj.gator]

I've found a couple of posts for guys putting turbos and blowers on their 2.5L Jeeps.  I am setting up an Eaton M62 supercharger off a Mercedes C230 for my Jeep but I'm not sure how much the stock bottom end can handle.  Assuming I can control detonation and get enough fuel, I would expect to run 4-5 psi without any problems but I don't want to throw a rod out the side of the block of my daily driver just to find out what the limits are.  I would hate to run 4psi when it can safely handle 7psi since every additional psi should yeild ~10HP on that engine.

Can any of you running forced induction please let me know what you've run on a stock crank / rods / pistons so I have a target to shoot for with the initial setup?  Thanks in advance.

[Tall Boy]

I don' think anybody's got it. I heard 5-6 is max for stock. Somebody was going to e mail me some schematics but...

[Yjeep93]

sorry I have no answers for you but I have a couple questions instead. What year is this supercharger from?
what kind of belt will you run?
Do you have any pix of your progress?
Sorry I don't no much about this topic but have been saving to get the avenger supercharger but if I could find a cheaper rout that would be awesome!
Thanks

[kenny kustom]

My avenger should be at my door by christmas. I will be running 6lb of boost. I am also running a split second fuel management system, along with larger injecotrs and tb. I will submit pics when i start the process.

[tj.gator]

I don't have any pics yet.  Just gettting the parts together.  Any year C230 should work although I am not a Mercedes expert.  I've been told the Eaton's are all the same.  You can get them off EBay for less than $300 if you watch. (This one is a little pricey I think)

http://cgi.ebay.com/ebaymotors/98-03-Mercedes-Supercharger-w-Electronic-Clutch-M45_W0QQitemZ130061056368QQihZ003QQcategoryZ33741QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

The Eaton blowers are also nice becuase you can mount them any way you want to and they work fine.  This guy has a similar setup to what I am doing.

http://www.hptuners.com/forum/showthread.php?p=37735

I am removing my AC and mounting it in its place.  The belt length will change but use all the existing pulleys.  The blowers off the Mercedes are cool because they use a clutch drive so you can turn the blower on and off.  They control off manifold pressure and throttle position.  I'm not controls savvy so I'm putting a standard pulley (don't know the diameter yet) on it.  I am closing off the silencer ports to get a little more efficiency (and a little more of the blower whine).  I'm trying to decide between an intercooler or just water injection with a progressive controller to help keep the temperatures down and control detonation. That may not even be an issue with 4-5 psi.  You also need to run a blow-off valve if the blower is in front of the throttle body to prevent a surge when the throttle body closes under boost.  You can route it to recirculate or dump to the atmopsphere if you don't mind sounding like a turbo Honda.  My plan is to pick up a set of Ford fuel injectors off EBay and rely on my adjustable MAP sensor to try to tune it.  More plans than time right now.
I drive my Jeep 80 miles a day so I need to have everything ready when I do it so I can tackle it over a weekend.  I'll post pictures when I get it done.

[wrangler387]

I'm eventually going to be boosting my jeep (turbo though). 10hp per psi isn't true. You may get more or less, CFM numbers, efficiency range, temps come into play along with how well your motor can move the additional air, and your timing/fuel blah blah blah blah blah haha.

I'd run an intercooler if i were you, i dont see any reason not to, you can find used ones from other cars for free-75 bucks. If you want you can run alchy/water injection also. Post pictures of your progress please, because that c230 eaton m62 is exactly what i was going to use to boost my jeep until my buddy gave me a few free turbo parts, i was going to try and wire the clutch to a switch though that i was going to let be triggered by my megasquirt. If the baby turbo doesn't provide what i'm looking for i may end up throwing either that eaton or an opcon/autorotor twin screw on my jeep, or maybe i'll step up to new garret GT series turbo.

If you can eliminate detonation and have reasonable temperatures (including EGT), then i dont see why you can't run 7psi. Tuning is the key, look at other cars (since boosted jeeps, especially ones that are tuned right are rare), one guy may blow his motor on only 9psi where as someone else may be running 15psi from the same turbo all day long.

[superman1456]

ive seen custom 4.6 strokers run 30psi and make around 700hp to the wheels so it can be done and can be done with grate sucess. just comes to time and money. more of the money part  

[kenny kustom]

My blower showed up yesterday from Avenger. I will post a writ up when i am finnished. Yay!  I can run premium again.

[wrangler387]

Definately post up some pics and reviews kenny kustom... I wish you guys lived around me, it would be nice to compare our set-ups in a few months when i get mine going. I guess i should say IF, other projects for the jeep keep delaying my attempts.

[tj.gator]

When I said ~10HP gain for each additional pound of boost I was figuring that my our little 2.5L.  I calculated the required air flow for a stock motor (130HP , Air Fuel Ratio @ 12, Brake Specific Fuel Consumption @ 0.55) to be 14.3 pounds / minute.  Taking that same engine and moving up 10HP the required air flow is ~15.4 pounds / minute.
Then assuming the intake air temperature is ~130 degrees (using an intercooler or water injection), a volumetric efficiency of ~0.95 for a 2-valve head, and an RPM of 5000, the required manifold pressure is 15.8 pounds.  If you subtract atmospheric pressure (14.7), you need 1.1 pounds of boost.  You can change the HP to whatever you want (assuming the engine and fuel can keep up), but for the 2.5L, it should net ~10HP for each pound of boost.  Did I miss something?

[wrangler387]

equations dont equal real world results, assuming the engine can keep up is the biggest problem with that equation (our head does not have a VE of .95). The jeep 2.5L is not a very efficient design. Look at the exhaust port of the 2.5L and tell me it flows good... Exhaust restriction, amount of flow your form of forced induction actually puts out plays a large role in hp numbers. The thigns are endless, how good you can remove the pressure buildup in the block, what cam profile you have, how well the head flows, how good the manifolds flow, how well your fuel atomizes, every little thing comes into play. Although the turbo or supercharger may flow X amount of air, how much of is actually going into and out of the motor....

[tj.gator]

It's obvious that you can't exactly model an engines performance using a computer or mathmatics but without doing your homework and getting a good idea of a target you are shooting in the dark.  With the restrictions of the 2.5L we don't have a big margin of error but I've run cars on over 20 psi and you waste a LOT of time and money if you don't get the turbo, injectors, fuel pressure, etc... sized and set up right to begin with.  I don't have access to any data or a dyno to meter exactly what volume of fuel and air are going in and out of the engine so all I can do is make assumptions to try to model the 2.5 as best I can.  Again, the 10HP per pound is making assumptions.  I have a MOPAR purple cam, a header, no conveter, and a low restriction 2.5" exhaust.  It will respond differently than a stock engine.  My fancy math and wild assumptions gave me a target that I need to shoot for.  The people at Avenger claim to make 181HP (+50HP over stock) with 5 pounds of boost which is 10HP per psi.  How does that work in the real world?

[Spyd3r]

So, after getting way off the subject, Does anyone know a safe number of pound you can boost at on a stock block.?

[chardrc]

i think it was somewhere around 5-7 psi.

[wrangler387]

I still don't see how you can think the head could have VE of .95, that is an amazingly good flowing head, i dont think a stock domestic has ever seen something like that. If you want to shoot for 10hp per psi then go for it, all i'm saying is that the 10hp per psi is a common myth people use for every set-up, reguardless of what they can actually flow. Obviously you have a better understanding then most, just wanted to make sure you were aware of these things and not get dissapointed if your motor doesn't make the hp you thought it would, or if it makes more etc...

Once again, it is not an amount of PSI that will blow your motor. Its mainly detonation, which normally will happen at set power outputs given temps, timing, fuel. Which is what i was trying to get across earlier, different set-ups yield different results. A lot of things go into determining when a motor will blow. You will be fine with 7psi from a smaller form of forced induction, only you can determine how far you can actually go by monitoring all of your temps and detonation. I'm going to be starting at 6psi out of the little 14b my buddy gave me, i'll be moving up from there.