Gavs supercharged V8 timebomb thread! (Eaton M112)

RobertE · Post by **RobertE** » Tue Apr 24, 2007 8:25 pm

Not sure about over in the UK, but here in the US those Eaton M112's are plentiful.. its almost ridiculous how easy they are to find..

The 4.6 DOHC Cobra uses them stock, and alot of people switch them out for Whipples or Kenne Belles.. quite often you can find them on ebay for a decent price.

Unfortunately I dont think theres room for a setup like the one above in the MG, and I definitely would like to keep the stock hood.

Suppose I'll just stay on the look out for a Vortech V-1

ihatesissycars · Post by **ihatesissycars** » Tue Apr 24, 2007 8:42 pm

Hey guys, yup Uwe sent me those pics, he was on the old forum for a bit. Why oh why has he gone to a 2.9??? Is he going to charge that?

Kev, Water injection sound cool alright! I can even control it via my megasquirt! It won't be brown water though. . . . .

So whats my first step to finding this out? Using 8.13:1 pistons seems like the logical step allowing for the most expansion later on plus the twin screw sc's are know for heating the charge up alot so again this will help which leads me to the next question, intercooler or chargecooler?

JP. · Post by **JP.** » Wed Apr 25, 2007 2:29 pm

RS composite headgaskeds will reduce cr from 9.35 till 8.65 so there's no need to replace pistons.
Don't forget..... Alloy blocks are more forgiving with higher compresionratios and boost than cast iron blocks. Has something to do with differend expansionrate and differend heat exchange.

I have reduced cr from about 9.8 ( milled heads) till about 9.2 with those RS composite gaskeds. I am running 7 psi with no problems at all. Well I have to say : I am running a MSD BTM system to avoid detonation.

ian.stewart · Post by **ian.stewart** » Wed Apr 25, 2007 2:53 pm

alex wrote:Thats a bit nice looking.
is it running?
Is a gilmer drive a toothed belt set up like you see on big rootes type blowers? I think they may whine allot?
Alex

The noise you can hear is the gearing between the Rotors, if the toothed belt was making the noise, can you imagine how many people would be moaning about the cam drives on their euro boxes.

ihatesissycars · Post by **ihatesissycars** » Wed Apr 25, 2007 2:54 pm

I'm building up a new engine anyways for this for which i need new pistons for so i may as well get the low comp ones whilst i'm at it but thats if i need a low c/r.

kiwicar · Post by **kiwicar** » Wed Apr 25, 2007 3:44 pm

Hi Gav
the amount of boost you use and the CR ar closley related (obviously), along with the type of cam, really it comes down to that old question of what are you using the engine for and what "charictor" do you want? low compression lots of cam and heaps of boost equals buckets of power and horrible to drive in traffic. Moderate boost and a sensable CR and moderate cam timing should be a pussycat and lots of fun in third gear but less power over all. (yes I am teaching my granny to suck eggs) but you need to think carfully about it and decide, not just build the engine around a chosen CR.
There is the Allan Allard book on turbocharging and supercharging(probably on its 27th revision by now) that has good tables for matching supercharges to engines and CR calculations but it is quite old in its thinking.
I would be thinking, based on a rover, of about 8.5:1 to 9:1 CR and about 7.5 to 8 lbs of boost, some really good heads

(not ported standard ones if you are going to use ported standard heads take .25 to .5 off the CR) and pistons to match.

A moderate road cam (220 to 225 at .05 of lift on the inlet an extra 4-5 deg on the exhaust) on a wide LSA (114 deg) but time it a little late (about 4 degrees after straight up) If you are mounting the supercharger as in your photos then put in an intercooler and HP water injection into the ports as a safty for the traffic jams (programme it off the megasquirt as you say). Should drive a treat and unstick the tyres when needed.

Actually if it were me I would spend the money on some decent heads and save on the supercharger bits rather than supercharge an engine with ported factory castings.
about to be shot down again.
Mike

ihatesissycars · Post by **ihatesissycars** » Wed Apr 25, 2007 3:57 pm

Wow awesome reply! I want as much hp as i can get out of the components i have basically. Its a weekend car so i'm not fussed about town manners and so on so i can go for it in the power stakes.

I will be having a cooler of some sort and the water injection as you say is a damn good idea for insurance so i will be doing that also.

Ref cams i've been looking at the s/c cam v8 tuner has for sale.

http://www.v8tuner.co.uk/product.php?id=483

Ref heads i have some uber ported and valved 5.0 griffith heads to go on this.

Whadda ya reckon?

kiwicar · Post by **kiwicar** » Wed Apr 25, 2007 9:46 pm

OK Gav
in that is the case go for 8 to 8.25:1 CR, 13 to 15psi boost definatly intercool or charge cooler and water injection into the ports. you will need good pistons, if you are going to use the rover heads as you have them then try and get some squish area by using dished pistons but keep the piston to head clearance tight. Use more cam timing, 235 to 242deg on the inlet again a bit more on the exhaust and keep the LSA wide (112 to 115 deg) and time it late 4 degrees again. Go much more than that and it will blow up without going to an all forged steel on the bottom end.
Be worth a check on the comp cams website to get some ideas of what makes a good blower cam, look at the chevy patterns, they are interesting differences to other normally aspirated cams.
Have fun
Mike

kiwicar · Post by **kiwicar** » Wed Apr 25, 2007 9:50 pm

Gav
that cam looks good for a blower on a 3.5 or 3.9, but you are going for a 4.6 base engine arn't you? you will want more cam for that 235 245 deg, especially if you want a bit of a yob of a motor.

Mike

ihatesissycars · Post by **ihatesissycars** » Wed Apr 25, 2007 10:11 pm

Well i'm using the 4.6 bottom end as i've heard nothing but good things about their pistons so thought i'd use these as forged jobbies are £750 minimum!

Stevie on here pumped out 500 hp via a low comp 4.6 bottom end and the pistons were fine with it (if i remember correctly). I was originally going to use a 4.0 rotating assembly for this reason too but its only because a 4.6 crank and later rods came my way that its now a 4.6 albeit minus some pistons which i've yet to buy!

So ref the cam its going to be a custom grind jobbie, where can i get that done? What about one of the standard cams, 3.9 or 3.5 efi?

kiwicar · Post by **kiwicar** » Thu Apr 26, 2007 8:08 am

Hi Gav
What bore is the 4.6? just I believe 305 chevy pistons can be used in some of the rover blocks, and these are about $150 to $250 a set (Marhl are only $460 a set) rods to match are the small journal chevy rods with a bit machined off the sides. If you use standard pistons then you could always arrange to spray oil from underneeth to cool the piston crowns, can make a big difference (though with the Rover you may have to arrange an extra oil pump! not that difficult, two stage external dry sump jobbie)
The grind need not be that "custom", comp cams do their custom grind service you select off their standard profiles and they grind the result, look at their Buick V8 section for a blank then look at the V6 and V8 selection for profiles, they can then grind a suitable V6 or V8 profile onto a Buick V8 blank at whatever LSA you specify, they even tell you what it will cost on the website. (look out for the really exotic stuff for the V6 though

)
I would think any of the major cam grinders over here (Kent?) could do a similar thing, select a "standard" inlet and exhoust profile off their catalog but ask them to grind it with a different LSA, shouldn't cost much more than a standard one as it is a programme in a CNC grinder.
Have fun
Mike

ihatesissycars · Post by **ihatesissycars** » Thu Apr 26, 2007 1:35 pm

Hmmm no i intend to stay with the stock 4.6 bottom end as its proven to be plenty strong enough for what i want and it's relatively cheap!

I'll have a look at those cams and seek some advice from the cam makes and see what they say. Thanks for the advice!

This is of course assuming i can get it to fit! If not its back to plan A!

GreenV8S · Post by **GreenV8S** » Fri Apr 27, 2007 6:18 pm

kiwicar wrote:OK Gav
in that is the case go for 8 to 8.25:1 CR, 13 to 15psi boost

If you're going for that much boost then the Eatons are definitely the wrong choice of blower, the efficiency drops off quite sharply with backpressure. You need to look for something with some internal compression.

RobertE · Post by **RobertE** » Fri Apr 27, 2007 8:12 pm

GreenV8S wrote:
kiwicar wrote:OK Gav
in that is the case go for 8 to 8.25:1 CR, 13 to 15psi boost
If you're going for that much boost then the Eatons are definitely the wrong choice of blower, the efficiency drops off quite sharply with backpressure. You need to look for something with some internal compression.

I agree.. they also heat up, which is never good.. you could use the same style setup with a whipple/kenne bell supercharger, they are fantastic at higher boost levels.

ihatesissycars · Post by **ihatesissycars** » Fri Apr 27, 2007 10:23 pm

This is the thing, i don't know what psi it will create in my 4.6's plenum so i need i guess to find out what it could do. In light of the last two comments i'm guessing a 9.35:1 c/rwould be good? The m112 is the blower i'll use, i can'tafford anything else so i need to build the engine around that.