Hey guys.. I'm nearing completion of my Eaton M112 (lightning, Cobra, Jag blower) on my LT1 and I need a little reading information on how to pick a good cam for fuel injected blown cars that should make and keep boost from 3,000RPM +

The Idea here is to make more power yet get better effecientcy on the highway than my current Hotcammed car. No dought forced induction is the way to go about it.

I'm thining of something like a ZZ3 which has little duration, Lots of LSA and tons of lift on the exhaust side (with 1.6 rocker) yet.. I read something where a guy got a 1300hp twin T car to live by planning where peak boost and peak torque occur. The ZZ3 would probally make peak torque right around where the boost comes in so hard.

The guy in the article (old popular hotrodding) basicly said "stuff starts breaking when peak torque and peak boost occur together"

Am I chaseing my tail here? What do you guys reccommend??

BTW.. here are some pictures of the project as of 3 weeks ago. Since then the injector bosses are in and the upper plate is tigged to the lower manifold.

http://www.coe.uncc.edu/~bktedder/M112LT1intake/

Here are some really really old pictures..

http://mywebpages.comcast.net/bherter/Eaton.html



Oh I really need some help with deciding compreesion ratio on blown motors too

Attached is the planned idler pulley, note: I see problems with the alternator slipping because the lack of surface angle but don't see any driveablity problems arizing

 

Injector positioning came up as a problem in this little experiment.

Here is the discussion on that
http://web.camaross.com/forums/showt...highlight=M112

 

The LT-1 is a pretty unique beast- both intake and heads. Stock, they run about 10.5: compression. But you don't have to look far to see that many guys don't get much life outta one if they run boost at the stock (high) compression. And they're even using comparatively efficient centrifugal blowers.

A roots blower of any kind will make boost instantly and fully throughout the RPM range. It doesn't ramp up like a centrifugal does. And having high compression isn't wanted or needed in most cases.

I'm going to recommend an arbitrary compression ratio of 9:1. Should be safe without making the motor into a pig at part throttle.

Traditional wisdom on cam selection says to run a mild duration cam with lots of lobe separation to keep the boost from blowing right through the motor during overlap. I don't see any reason to deviate from that general wisdom. Especially since you're exploring uncharted waters with this project.

If you're going to miscaculate it's always better to miscalcuate on the side of a smaller cam and lower compression.

 

First, don’t run 2 tensioners… that’s just going to be a nightmare.

Why not put the idler where you’ve got it now or lower and then run the belt between the blower and the alternator under it so that you get more belt wrap on the alternator pulley and run the belt coming off the PS straight to the blower. The only thing that I could see possibly getting in the way is the thermostat housing and it’s would be easy enough to modify that and reweld it so that outlet comes forward and around the belt.

For that matter, I’m not sure that I’d run the blower off the same belt that you’re running everything else. I bet you’ll start wearing out bearings in the accessories. Remember that this thing is probably going to draw 30-50hp from the belt, and that’s just going to put an extra load on everything. At speed that blower will introduce quite a bit of strain and harmonics into the belt setup. For that matter a broken or thrown blower belt wouldn’t be nearly as big a catastrophe on a road trip as if you were using one belt for everything.

WRT to the cam… for the most part unless you plan on doing it while you’ve got the intake… off then I’d run what you have and worry about it later. If you’re going to try to come up with a grind specific to your setup, remember that your power curve will basically be what the blower pumps out at the rpm you’re turning it, it’s not like turbos or even centrifugal blowers that then need to spin up some to work. You could do all sorts of things to try to fight the blowers natural tendency, but for the most part, positive displacement blowers are happiest with cams that basically put your power band where the blower works (from idle on up in your case) and with a little more LSA then you would have for an NA cam with the same setup. If you want someone to talk to I’d try Magnusson, B&M and Holly, and see what they recommend for their positive displacement blowers. Vizard also has a discussion about this in his sbc valvetrain book (forgot the exact name) but it basically amounts to what I just said.

 

Hey Thanks for the input.

That picture if you look in the Legend I made it says idler so i did have that planned out like your talking about. The picture is also kinda rough guess or just a representation of what i have dreamed. When I have the car down I'll place the extra tentioner in a spot that keeps the belts from touching, provides good alternator rap, and doesn't interfeer with the many coolant lines in that area.

Do you think running the same belt is really going to be detrimental on accessory life? I found a guy who put the same blower on a late model modular GT and that was one thing i noticed that he had it all on the same belt. He had even fabbed up some extra idlers to get the belt really really wraped around the blower. I'm not sure if the cobras are like that or not.

I've been concerned about finding a belt with the proper lenght

Off Topic:
That mustang I mentioned above was really pretty awesome. He had the benifit of the GT's (aluminum block, solid axle, lighter) paired up with the cobra blower. He said hes seen 18psi with it. I did witness the car run a few 7.0's in the 1/8th

 

 

Rooster, I think you’re misunderstanding what I’m getting at. I realize that in your picture one is a tensioner and one is and idler. I’m suggesting that you get rid of the second tensioner (after all, there already is a factory tensioner on the bottom), and then use the idler in the location that you have it to get more belt wrap around the alternator.

2 tensioners will work against each other and will make it next to impossible for one person to put the belt on.

WRT to finding the right belt… that’s fairly simple. Most good autoparts stores will stock them in most lengths or can at least get them. If you stick with a 6 rib, there’s tons of sizes out there.

 

OH... duh..

I took this picture from someone else... Disregard that yellow non filled in circle with the caption extra tentioner

i only plan to use a idler and stock tentioner

 

Just in case you're not still not following what I'm getting at (I doubt it, but just in case) I took and modified your picture. This way you pretty much get maximum belt wrap on everything, actually, I'd move the ilder down as far as you can without hitting the other side of the belt, but you get the idea.

 

ah... i see.. that is very interesting.

Thats why we got to put up pictures. Its too hard to explain everything

Like you said the major issue would be the 3 coolant lines that intersect there.

very very interesting though.. i'll keep it in thought when the blower is actually sitting on the car

 

Got a little further in the project.

For those interested still

 

a

 

b

 

c

 

Well, you're in it up to your eyeballs now, man!! ***, I hope this thing works out well for you. Goes without saying that NOBODY else has a setup like this. My thoughts and prayers go with you.

You'll need them!

Seriously, good luck. You gotta send me an email when you get the thing running, even if you don't post about it here. This project really grabbed me. I LOVE when somebnody tries something really really different (but still do-able for a backyard mechanic with some experience).

 

Ditto!

 

I thought blowers with lobes needed to contact fuel at some point otherwise they would heat up and expand and the lobes would touch causing failure.

The only reason i didnt retro-fit my new 142 weiand blower with Mutli point FI was because the injectors would be below the blower meaning fuel would never touch them?

Now that makes me wonder. all the eaton-charged motors like ford lightning now come with MPFI and have blowers that dont touch the fuel. i suppose this "rule of thumb" only applies to roots blowers as opposed to screw type blowers?

what am i missing?

 

Eatons are not screw types, they're lobed just like other roots blowers, but they have 2 lobes as opposed to 3.

 

My roots blower has 2 lobes also. is it identical to those things? I thought they spun and pulled air from back to front as opposed to from top to bottom?

and what about the whole heating up and expnding thing?

 

Thanks guys for the words of incouragement.

I couldn't build a upperintake before the semester was over so I went out bought a welder and pile of scrap steel and began teaching myself how to weld. Its coming out pretty well the welds aren't like jesse james but they are sorta decent and totally functional.

By upper intake i mean from the blower to the throttle body.

I finished my fuel lines and injector bosses.

I've yet to build a idler pulley (as mentioned before). A friend who is a machinist thought i should use a nice skate board wheel but i would rather find a pulley in a junk yard.

I've got a picture of the blower sitting on the manifold and the injector rail and injectors in but it won't let me post it

 

new picture.

I'm waiting for my gaskets to come so i can cut the holes in that upper and weld the upper plate to it.

Not bad for first welding job eh?

 

anthor

 

yet anthor

 

One word: functional. Not pretty, but looks like it will get the job done. Hurry up!!! I need closure!!! You GOTTA get this thing running!

BTW- I can't weld worth a damn, so you're still way ahead of anything I could do.

 

BTW- have you worked out the pulley ratios yet? A magazine I read recently said these blowers displace about 112ci per revolution.

My Weiand 142 displaces 142ci per revolution and will make about 5 PSI on a mild 383 using a 2.10:1 drive ratio.

Doing the math you'd need about a 2.43:1 drive ratio to feed an equivalent 350 @ 5 PSI using that blower, all else held constant.

There's a LOT of assumptions and "theory" in that number, obviously, but it should get you close to reality, anyway.

 

What it ends up looking like is up to him. If he's ambitious, he can grind even the gnarliest welds flat and polish all of them.

WRT to your calculations, that would hold true if it had the same efficiency as your traditional style roots, but eaton made a bunch of refinements that make it MUCH more efficient. The 112 probably flows more air then your 142 at the same rpm. My brother’s car is running a modified M90, that at a 2.8:1 ratio is pumping enough air for the TFS intake and TFS headed 306 ford to see a peak of 10psi, and enough hp to so far run 120mph in a 4 door LTD chassis.

Figure his 112 has 25% more displacement and the same design. I’ve been trying to talk my brother into letting me cut and notch his passenger size strut tower so that we could fit a 112 and then flirt with 9’s in that car.

 

Well I wimped out today.. After getting frustrated over the metal bending about 4 inches away from where i was welding and screwing up my mating flanges I took the blower and throttle body to a local race car fabrication wizard to build a upper intake for me.

hes going to build it out of 1/8th inch aluminum. He is truely the Jesse James of the south east as far as I'm concerned.

I'd rather have something i can be proud of rather than something i don't want to show to others.

SO...

Still waiting on FMU and T-rex to arrive in the mail
Now waiting for the upper to be done



The bit about how much boost it will make well.... heres my therory. I think they make 8lbs on a stock 5.4 lightning so consdidering my car is a 350 and makes 410FWHP NA it should make 4-6lbs with the stock pulley. I would honestly be happy with 4lbs right now. The motor does have 132k on it!

 

BTW

I built the Idler pulley out of a piece of 1/8 angle steel and a 76mm steel 6 rib smooth ball bearing pulley



Does anyone know where I can get a vaccum actuator for this thing? The dealer wants $190!!

 

Awesome project

I anxiously await your finished results. My only changes will be to space the supercharger up off the intake manifold by 2" (or more) with an intercooler setup like the GTP uses. I'm hoping to use the factory injector bosses by doing this and factory fuel rails with new front x-over line. Since we Impala SS's have a little more room I should still be able to put a cowl induction hood on it and make it fit.

I am also going to just use the factory Ford upper intake tract so I don't have to fab anything up on the top end other than a Ford to GM throttle body adapter.

Mike

 

Isn't the vacuum actuator to bypass it when at light throttle? If so, maybe just forget about it (for now). Roots blowers have been running for years without fancy-schmasy bypasses!

Anyway- even at 4 PSI it'll be a real kick in the pants. My 142 is only making about 5 PSI right now on my 383 and it's a HUGE difference over the same combo running N/A with a dual plane aluminum intake.

4 PSI at all RPMs feels a lot stronger than a centrifugal that only PEAKS at the same pressure.

 

Crossfire- I ran some calculations and we're not that far apart. Given your brother's smaller diplacement and the higher pulley ratio 10 PSI is about where you'd be with a 112ci displacement blower.

Obviously, it's very difficult to make apples-to-apples comparisons since the cam and heads can make LARGE differences in the actual observed boost. And your brother's enging sounds like it would gooble up a LOT of boost for it's displacement vs. my relatively mild 383.

No doubt the Eaton unit is probably overall quite a bit more efficient than an ancient Weiand/Holley design.

 

heres a picture of the boost gauge...

 

a

 

nb

 

I installed a Autometer Boost gauge 2 1/16's believe it or not but a front oil pan seal and the gauge fit perfectly in the factory firebird A/C vent


I also installed a vortech T-Rex fuel pump. Boy what a pain in the butt.

I also got a vortech FMU 10:1. The car is speed density with a optispark so I'm pretty much stuck with it.

I think tomarrow I should have some pictures with the intake on the car and the fuel lines completed. Friday I hope to have the blower mounted and throttle cables finished

After that besides a bunch of tuning I think i'm done...

 

Hehe....me knows better than that...

 

Is this a typo or did you misunderstand me? He's using the smaller M90 (90ci), and it's seeing about 18000rpm at the shifts.

To be honest, that's one set of #'s that I haven't played with... I just looked up (and interploated past 12000rpm) eaton's published compressor map...

 

You guys should be able to use a M112 no problem.. Ever think about butchering a upper 5.0 intake for one?

I was orgnially going to use a M90 on this car but seeing how it makes 340rwhp na I didn't want to put something that i would out grow so quickly


I did save the M90 that i aqured and plan on using it on dads mustang next year. I think i'm going to mount his above a valve cover and run the output to the intake and a throttle body on the imput side of the M90... Oh did i mention I plan on using a 749 and GM throttle body? should be interesting.

 

anyone have any ideas what I should do about that valve? I think i'm just going to wire it shut for the time being..

 

The problem with the 112 is that it’s longer with the air intake facing a different direction. To mount it in the place of the M90 the strut tower would have to be cut. I’ve got a few ideas how to do it but my brother is pretty skittish about it, and I really don’t blame him.

You have to remember that 5.0fords are significantly narrower between the heads then a SBC, so there is less room to mount the blower straight to the intake. He seems fairly attached to his TFS intake anyway.

I really think this thing will see 10’s without anything else (well, it lost it’s over the axle pipes, got larger dynomax mufflers and turndowns yesterday), and then we’ve still got a few ideas on where to find a few more HP after that.

My brother really wants to find a T-bird SC autorotor replacement blower to see if that can be pushed farther. I don’t think it will work. Hell, we’re about 50% past Eaton’s published design limits now, the car is running a full second faster then the fastest SC with that blower out there, as well as all the KennyBell Instacharger (same, M90 blower) cars. I want to try a little more case porting and either slightly more RPM or coating the rotors (HVLP gun + epoxy ) to see if we could get it to move a little more air.

Really, the thing doesn’t _need_ more power. It’s more of a street car then a race car. I think that he’s going to try autoxing it later this year (should be fun, 500hp + only room for a 26x9” tire max ). He keeps hinting that he wants to buy my T3’s off me and get me to make him some custom manifolds for it, we even took a serious look at it and measured out what would be necessary to route 3” down pipes the other day.

The GM TB is a no brainer on an M90, since they’re basically the same shape and similar sized. For that matter, if you’re interested in using any engine management with the exception of the ford EECIV you’re better off converting to gm sensors anyway.

I’d just wire the valve shut. What do you need of that bypass valve? I may have the canister/actuator off an M90 somewhere (we cut the actual assembly up and converted it to a cable operated manual linkage and had it welded to the discharge ducting, so the canister is sitting around somewhere)

 

just the canister.. I'll make it work. I think a wastegate actuator off a GN turbo would work too.

Have you guys actually measured a real life M112 to M90? they didn't seem that much apart. the M112 is definately longer yet shorter and same width wierd how things like that work.

oh yeah. I definately agree GM has thier **** together with the EFI stuff. I just began tuninga few fords around town and so far I'm not pleased with EEC4

 

Well Alvin it looks like it is coming along. You think you will get finished before you have to leave? I was only joking about the skate board wheel, I am glad you got a real pulley. Have you begun to cut the lower intake yet? I want to see how that turns out. Take some pics when you get the lower cut, just be carefull I don't want to make it again.


What's wrong with my tune? It only took 3 tries, it runs great and it handles the 52.7% oversided injectors.

 

Here are some pictures of how its coming along.

A few of the pictures show a M90 mocked up on the car. this is because my M112 is at a professional fabrication shop getting a upper intake built. I tried it myself but as you can see in the other pictures I suck at welding BAD

The upper should be done tomarrow and all I have left is to drill and tap the upper intake for vaccum fittings, cut and tap the lower for the blower (easy job), and tighten everything down. I expect to be driving the car either tomarrow night or saturday depending on when i get the blower and upper intake back.

I'm using a Crane HI-6S for ignition/retard, vortech FMU (speed density car), vortech T-Rex, ford SVO 30lbs, and autometer boost/vac gauge.

I'm also doing something very very unorthadox with the injector bosses... we will see if it works

ENJOY
http://community.webshots.com/album/73249682zNpxhw


__________________

 

Crossfire- yeah, I misunderstood. I didn't notice we were comparing blowers with different displacements.

 

thats a little on the ugly side so what kind of HP does that ride have now

 

why hassent anyone poster owell do LT1 have electric water pumps??