M42 Rotrex (for sale!) + track build

[magpie]

i hope these are mean beanze



any more progress?

[rix313]

I ordered some super flexi hose from SFS Performance, to make my breather and idle hoses. The fact it flexes so well allowed me to easily bend and route the hoses. I hopefully won’t be running the engine as standard for too long, so I don't have an ICV (Idle Control Valve), this does mean that when the engine is cold, it won’t idle correctly but once up to temperature it will be fine.






Quickly knocked a bracket up to hold my dipstick tube in place too:






I have also made this redundant:




The centre section has been badly bodged and considering I’m spending all this money on new components, I’m not going to leave this part out. So Magpie hooked me up with this stainless power-flow rear end with BMW front end







Not sure how I feel about the bazooka look so may get a freind of mine to chop the tube off and weld a smaller one onski

Nice


P.S. Spoke to Turbo-Brown and I'm taking my spare engine to him at the start of September so he can make me some super charger brackets

[appletree]

Jesus christ rich thats huge!!!! wait till you go over the first speed bump and off that will come. What size is it by the way? looks like 5"

[magpie]

it wont come off trust me

my car is lowered 4omm on eibachs and it was fine.
did you get it fitted ok in the end?

[rix313]

LOL, when I get a smaller tube on the back it'll sit higher. No speed bumps between here and the race track any way

One hook is on the mount and the other is currently cable tied just so it's up there. I need to have a look and a faf and get it set up properly

[magpie]

that's how i had it without cutting the val,
it never hit any speed humps and there is bloody millions of em in southampton

[rix313]

I noticed, had such a crap drive in, accidently selected 'avoid motorways' on the satnav and got the scenic route through Southampton

[magpie]

when is the charger being fitted,
is the g,box on yet?

fire it up!!!

[rix313]

I added a bit to the bottom of that update, I'm taking my spare engine to Turbo-Brown in September to have the brackets for the super charger made up

Gearbox is being done Tuesday!!

Exhaust is going to the fabricators tomorrow to be sorted

[hoshy]

wtf is that rich. get it off there asap mate!

[rix313]

Wait and see having the paint can swapped for a 2.5 or 3inch pipe instead, much more nicerer.



Got a technical question :

Cometic head gaskets. If I was to buy a thicker one (cheers Gunni ) to slightly lower the CR, what size one do I need to look at getting? Can ny one tell me the stock CR, head gasket thickness and what sort of CR I should look at trying to lower it to with the gasket?

[Gunni]

thinner = higher compression
thicker = less compression

[hoshy]

You need a thicker gasket to lower the ratio, thinner increases it.

Bear in mind that the hea might have been skimmed a couple of times in it's life, that's why BMW offer a thicker version along with the standard one.

It's hard specify a thickness unless you've got a compression ratio in mind that you wish to target. You should be able to find some maths on what ratio would be good for the boost you expect... You might find that the stock ratio is fine but I'd still be inclined, based on my experience, to drop it a little.

Stock ratio is 10.1:1 (assuming stock headgasket and unskimmed head).

[rix313]

Might be a good excuse to look at my Supercharged! book

This is where I'm really going to be needing help. What sort of boost can I get/run from the M45?

This is obviously where it starts getting technical, just been doing easy turd until now

[GeoffBob]

Rich, all depends how your supercharger is geared to your crank and thus, how much boost you will be making as a function of engine speed (at wide open throttle). I stand corrected but I think Appletree is currently limited to around 5000RPM with his 10:1 M42 since he runs the risk of detonation above 5000RPM (as his boost increases with RPM). I therefore suspect that you could land yourself in a similar boat if you don't lower your compression ratio. The amount by which you should lower your compresion ratio can be determined based upon how much boost your Eaton will be making as a function of your engine speed (RPM). Of course, if you don't want very much boost (and have geared the Eaton to pump as such) then you can keep your compression ratio as is. I do however feel that you might have more fun with your supercharged M42 if you were to lower the compression ratio slightly.

[rix313]

*I have edited this alot so might be worth re-reading?*

I know Matt and Ash managed to successfuly run theirs without changing the compression ratio's. Ash did how ever recommend that I do look at lowering it slightly and the easiest way without major work is by investing in a Cometic gasket.

I've contacted Cometic but they obviously need to know the current CR (10.1:1), current gasket thickness, then what I need the CR to be.

Just spoke to Omi, said he changed it for the thicker one which is 2.04mm in 2006.

I take it the gearing is worked out using the diameter of the crank pully and the diameter of the S/C pully? What equation can you throw at me for that? where do I go from there? Crank pully is 140mm and the charger pully is 65mm.

The other thing I want to know is, is using a headgasket a bit too simple when attempting to lower the CR obviously not by much but all the same? It'll be fab if I can gain from something so simple but is it abit futile?


Cometic's range is from 0.65mm to 3.5mm in approx 0.12mm increments

[GeoffBob]

At a rough guess I'd say you could do quite well with that range of gaskets. I'll post more later as right now I have to go help a friend with a gearbox. I'm pretty sure I can help you work out the numbers for your engine. Working out the gearing by the pulley ratios is quite easy. More later. Bye.

[rix313]

As far as the ratio for the crank pulley : super charger pulley, it's spot on I know its been worked out but what ever

S/C RPM at desired airflow
Gear ratio of roots x redline

15000RPM (based on what Matt ran his at)
1 x 7000

= 2.14


Charger pulley size = 65mm

65mm x 2.14 = 139.1mm (Mr Bell says expect it to be within 1mm )

The M43 crank pulley is 140mm.

Doing it the other way round it comes to 2.15 (140/65)



Also roughly worked out what PSI I'm going to require:

Desired BHP
Current BHP

200
135

= 1.48

Boost = 0.48 x 14.6 (atmospheric pressure)
= 7psi


That look about right or a total load of brown stickyness?

[appletree]

Rich when i did mine i ran the same charger pully and crankpully as you and got 8psi at 6500rpm with no problem even though mine ran hot so yours should be ok running on stock set up with your intercooler as it should in theary be better than my charge cooler as it did suffer from heat soke.

if i remember rightly the charger has a max RPM limit of 14000rpm using the M43 pully i worked out (hope it was right) that at 6500rpm (my old rev limit) i was getting 13800ish rpm out of the charger so it was running at its max and made 8PSI think hoshy got abit more PSI maybe 9-10 possibly because of my poor flowing inlet to the charger (the 180d bend bit) and the laminovers being in the inlet manifold possibly restricting it. although they did make simular BHP with hoshys making 10 or so BHP more than mine

Dont bother with a comtec gasket rich just by the BMW+ size one and bolt it up.

Ant mapped a standard M42 with a turbo at 11psi on standard internals and it was fine.
Also if you look at the MK2 golf boys they run 10psi on there 10:1 1800cc 16V of the same era.

OOO and sorry its taking so long to get the loom info to you i'm just realy busy and abit slack to LOL are you coming to the santapod in sept??

[rix313]

It does have the larger 2.04mm gasket fitted and it's fairly new too (3 years).

The Cometic isn't going to be a now thing, rather a later on.... thing. The profile gasket is marginaly sweating oil and I will eventualy want to change that and might do the Cometic at the same time.

Having said that I am very keen to see and learn the appropriate calculations etc

OOO and sorry its taking so long to get the loom info to you i'm just realy busy and abit slack to LOL

I should say so Thats cool bud no major rush for them

When's the pod event?

[appletree]

Performance BMW show sure itll be in the meets section, a good few cars come and anit more performance oriantated

http://www.bmwshow.co.uk/

[Gunni]

Turbo would have been so much easier and overall better.

[rix313]

Shoosh lol! I had thought about it but I do like that charger whine

[GeoffBob]

Rich, if 7psi (roughly 0.5 bar) boost is all you require to get your desired HP then do exactly as Appletree described above. You shouldn't have any problems on stock internals at 7psi boost.

However, be careful of comparing your work to Ant's 11psi turbo job as a roots pump type supercharger (such as the Eaton) is a lot more inefficient than a turbo and thus puts a lot more heat into the air that it pumps, and the temperature of the inlet air has a marked effect upon the probability of detonation. Thus, if (say for arguments sake) 13psi boost is the limit at the stock compression ratio (without exotic fuels, water injection etc) then you'd likely only make it to say 10psi with a roots pump (assuming the roots pump is geared to make it there). This is also assuming you are comparing systems with identical capacity air cooling (same charge cooler, intercooler etc). Heating of the pumped air is generally a problem with roots pumps, and I agree with Appletree that you should, therefore, do well with your large front mounted intercooler.

Turbo would have been so much easier and overall better.

Gunni, do you EVER have anything good to say? Time you posted up one or two of your projects so we can find fault with them. Wouldn't want you to have all the fun.

[rix313]

I don't suspect my charger inlet will flow much better than yours Matt if I decide to mount my TB before the charger.

Be interested to see how much difference my FMIC makes, I guess if it brings the temperatures down further from the systems Ash and Matt used, I shouldn't have to worry too much about the CR as the air should be cooler therfore reducing the risk of detonation etc? Am I on the right track? You where seeing what 204BHP Matt with the laminovas? Ash was 209BHP with his cooler behind the head lights.

How do I work out my CR wth the larger BMW gasket fitted?

[GeoffBob]

Yip, you're on the right track

Compression ratio CR = V1/V2.

where:

• V1 is the combustion chamber volume with piston at BDC, and
  V2 is the combustion chamber volume with piston at TDC.

Both V1 and V2 include the volume contributed by the roof of the combustion chamber in the cylinder head.

Graham Bell provides instruction in his book on how to measure the volume contributed by that fraction of the combustion chamber in the cyclinder head by placing a piece of clear plastic over the up-turned head and slowly filling the top of each combustion chamber with spirits from a graduated pipet. I think Turbo-Brown shows how he did this on his project page.

You can also measure the volume of the indents in the piston crowns for the valves in the same way. These must be taken into account in both V1 and V2 since they contribute to both.

The volume of that portion of the combustion chamber inside the block is much easier to determine and is simply the volume of a cylinder whose length is equal to the depth of the piston into the block plus the height of the compressed gasket.

Obviously, in you calculation of V2 you must account for how high the piston rises relative to the top of the block (just shy, inline, or slightly proud), and then either add (if shy) or subtract (if proud) this volume from the head volume (measured with the pipet) plus the volume contributed by the gasket.

[hoshy]

That 209 was on the Dyno with a very powerful fan on the IC

You have got the right-end of the stick there though yes. And I do agree with Matt that especially given your better cooling you should be ok on stock CR but I'd still be inclined to err on the side of caution - certainly an MLS gasket will be stronger and less prone to failure from track abuse even if you make negligable CR adjustments.

Not sure on the formula to work out HG CR adjustments but google should turn up a load of sites.

[rix313]

The car is going to get a relavtively easy life this side of 2010 I imagine. Next year it WILL be given hell and I will compensate for this by upgrading the HG for something stronger (what ever that maybe), I'll do the profile one at the same time as it is sweating oil.

[march109]

Frankly I'd rather leave the HG stock or at least if not stock the weakest link in the chain, I'd rather be replacing that than something else!

[Gunni]

Rich, if 7psi (roughly 0.5 bar) boost is all you require to get your desired HP then do exactly as Appletree described above. You shouldn't have any problems on stock internals at 7psi boost.

However, be careful of comparing your work to Ant's 11psi turbo job as a roots pump type supercharger (such as the Eaton) is a lot more inefficient than a turbo and thus puts a lot more heat into the air that it pumps, and the temperature of the inlet air has a marked effect upon the probability of detonation. Thus, if (say for arguments sake) 13psi boost is the limit at the stock compression ratio (without exotic fuels, water injection etc) then you'd likely only make it to say 10psi with a roots pump (assuming the roots pump is geared to make it there). This is also assuming you are comparing systems with identical capacity air cooling (same charge cooler, intercooler etc). Heating of the pumped air is generally a problem with roots pumps, and I agree with Appletree that you should, therefore, do well with your large front mounted intercooler.

Turbo would have been so much easier and overall better.

Gunni, do you EVER have anything good to say? Time you posted up one or two of your projects so we can find fault with them. Wouldn't want you to have all the fun.

My 2.8 project is in the galleries thread.
http://www.e30zone.net/modules.php?name ... ight=400hp

And if I had to do it again, I would have made a manifold from scratch and used a split pulse HX35.

[rix313]

Frankly I'd rather leave the HG stock or at least if not stock the weakest link in the chain, I'd rather be replacing that than something else!

Trouble is head gasket failure generaly couples it's self with wanking the head

[appletree]

Cough 205.5bhp dont you know

I know were your coming from rich but mine wasnt driven slowly and had trackdays at donnington and went to the ring and spent most of the trip being booted from 70 to 90mph trying to keep up with the impezas in the group and even with my 3.91 diff was still reving high. I'am also still on the origional HG bmw sold the car with on both set ups

[rix313]

LOL alright 205.5

[GeoffBob]

Rich, better late than never I guess.

See below the compressor map for the EatonM45 (as published by Eaton) with my calculations (in red) for your M42 engine plotted on top of the M45 data. This is as I did for Appletree's Rotrex.

Since your pulley ratio is 140:65 you can expect your EatonM45 to spin 2.154 faster than your engine. Thus, at an engine speed of 6500RPM, your Eaton will be exactly at its redline of 14000RPM.

On the graph the calculated broad red line indicates the pressure ratio the Eaton should develop as a function of the airflow into the compressor (in this case in m^3 per hour).

Note that the pressure ratio is calculated as the ratio of pressure across the inlet and outlet of the compressor. For example, at an engine speed of 6500RPM the EatonM45 should deliver around 0.82bar of boost (assuming an inlet pressure of 1bar). However, don't expect to measure 0,82bar of boost unless you place your boost guage at the compressor outlet. Measuring at your plenum (after your FMIC and however many elbows you may have in the pipework) you can expect the pressure to be a little lower. You should, however, expect to be making close to 0,45bar of boost at an engine speed of 2000RPM.



Hope this is of some help to you.

Regards,

[Ant]

@ All

I have the pinouts for the JPT88 on the stock ECU, anyone wishing to add a standalone perhaps hacking the original plug off and making a plug and play style standalone ?, this how I added MS to the 0261 200 175 ECU on the iS I just completed.

lemme know if you need these, happy to post em up for all