M42 Forced Induction Advice please.

[ShepsM3]

I was baseing the figures on what I have seen on previous NA cars I have converted to FI using the Rotrex SC. Usually I see 60% increase with 6psi of boost once the management has been live mapped on the rolling road (by me). Depending on how well the head flows and how good the exhaust is, 12psi I can usually double stock power. But maybe I am lucky to have achieved this so far?

Yes, Injectors are very limited, also I would use a rising rate with boost FPR. Probably uprate the fuel pump, although the standard one will probably be upto the job.

I am looking to fit as large but thin as possible intercooler with large "face" surface area for optimum charge cooling, so inlet temps should stay nice and low.

I am hoping the head gasket or engine doesn't blow. I would like a reliable car right from the word go, so I will look into better head gaskets and ARP head studs/nuts. I am not liking the idea of running the car with non forged pistons though. I was hopeing they would be forged as standard.... can't have everything lol.

[JiXer]

I just came upon a DASC that is totally unmodified.
I plan on installing it as is and doing a dyno run to see where the numbers and AFR baselines come in.
My plan from that point is to try the cheater CR decrease with a thicker head gasket, but I am trying to find out how thick I can go without ruining the quench and the ability of the combustion chamber to efficiently burn the charge.
Does anyone know anything about that? How thick can I go?

Also, is a smaller pulley all I have to do to increase boost?
What about the bypass thing on here? It is not like anything I have ever seen but apparently popular on these Eaton blowers. It returns excess boost back in to the blower. Pretty smart design, but I imagine it has to be modified to ensure the increased boost goes where it needs to.

I will also be doing away with the AFM and run a Megasquirt off of MAP with larger injectors. Probably going to shoot for 10-11 psi. Any idea what injector size I should install?

Thoughts?

J.

[rob_e30]

I will also be doing away with the AFM and run a Megasquirt off of MAP with larger injectors. Probably going to shoot for 10-11 psi. Any idea what injector size I should install?

Check out RC Engineering at this link:

http://www.rceng.com/

Click on Technical Notes/Sizing.  Injector size is a function of expected HP, fuel pressure, forecast fuel consumption, duty cycle, and number of injectors.

[ShepsM3]

Right people, small update.

I have been real busy with work of late and as Summer is comming I decided to pull my finger out and get buying some parts.

I fitted the Evolve (E30Zone) chip which gave me another 6bhp over what it had before. It also took away the rev limiter so I decided to fit a Dastek Unichip aswell and lower the limiter to 6800 RPM as peak power was long gone by then. I am kinda expecting the peak power to be past 7000 RPM or around there so thats why I got an Evolve chip as it raised the limiter beyond this.

After speaking to Tim_S about his polly vee pulley kit he has on his car, I purchased an E36 318is pulley kit with front crank damper with matching crank sensor, alternator with matching bracket, pas pump, and water pump pulley. Also the tensioner to keep things tight.

I already have the Rotrex SC, but I have 2 sizes. One does upto 2ltr (18psi) and the other does upto 4ltr engines. I was thinking of using the smaller one as I don't want to have much more than 10-12 psi on the stock internals.

Appletree assures me the pistons are Forged in our M42's, although Tim thinks different. I have a few of these engine kicking about and am prepared to blow one up if it comes to it lol.

I will be mounting the SC where the AC compressor would normally be fitted. I will also be fitting a large custom made front mount intercooler. I will also be fitting an oil coler for both engine and SC. The intercooler will have a large surface area but will not be "fat". I will be drop kicking the viscous fan over the nearest hedge and installing a large slim electric cooling fan to the radiator. I want also to fit a larger radiator to help cooling.

I need to work out the injectors I require for a bar of boost. Not that it will get that high, but I don't want to be running 100% duty cycle either. I may also fit a raising rate with boost FPR to help things here too.

While I am there, I will be fitting a sterring rack from the E36 318is too, anyone know how much less turns this is over the E30 rack? This will make the conversion to the E36 pas pump easy as I can use the pipework too.

I also need to calculate the SC pulley size to the crank pulley size as I dont want to be over revving the SC past its max capacity. But saying this, I will be fitting a boost controller which will open and close a blow off valve which should allow me to run the SC very close to max capacity at max rpm, this will allow the SC to start boosing from much lower down the rev range, also with the boost controler, I will be able to up the boost - or lower it very easily. One thing is for sure, it won't loose boost right to the limiter

The Battery is going in the boot aka M3/325i sport. There will be a reservoir for the SC special oil and a catch tank/breather where the battery went.

Anything I've missed? Any constructive comments would be greatfully recieved

[agreen]

Good luck paul, hope evrything goes well i can not wait to see this up and running ,

Arron

[Appletree IS supercharged]

hello everybody!!! been reading things in the background but i thought id post abit now!

Ive read in a few reputable books now that the M42 does have forged pistons as standard but that it have lighted conrods NOT forged.

Also read and seen afew pics of M42 with a conrod out the side of the block even though they havent been running boost or overly tuned N/A just tryin to get top speed on the motorway  *** Private runway***  Not good!

mines been runnign well with 8 psi the main problem with mine i belive is the inlet temps which are to high and ive now started to work on getting them done.

As some of you from the zone know ive got my H-beam rods no and spent today strippingthe block down to see what condition its all in.

Is there any way of checking wether somthing is forged or not??

Just looking at the conrods they look cast as there looks to be abit were they have been cut off from alarger bit of material and then machined flat.

[tim_s]

hey fellas! Matt, check the BM technical info for the M42, states rods are forged steel, and no mention of forged pistons. This tallies with what I thought when I pulled an m42. Pm me your email, I'll send you.

[ShepsM3]

If there is any doubt on the rods or pistons, I will get another engine built up using special pistons. But I intend on keeping standard CR although I may play around with this a little

Matt, I havn't forgot your pics mate, just not home right now but will take some within the next couple of days.

[Appletree IS supercharged]

Ok mate, i for got to say that i'am running rover K-series injectors from the 1.8 16v there biage/creamy in colour and at 200bhp they were running at 80% cylce with 4bar feul pressure.

[ShepsM3]

Ok mate, i for got to say that i'am running rover K-series injectors from the 1.8 16v there biage/creamy in colour and at 200bhp they were running at 80% cylce with 4bar feul pressure.

That makes sence, I just mapped a Lotus Elise with a 1.8ltr K series Minister engine with standard K'series injectors. That was at 100% duty cycle over 6700RPM and was running a tad too lean for my personal liking at 7500-8000 RPM. That had 221BHP in the end. I am sure the FPR was a 3bar standard item though.

I'll think I need some different ones to those?

[Appletree IS supercharged]

If you find some bosch fiment ones that run 230-280 bhp drop me a line and let me know what there out of please!

I did look at VAG 20VT injectors but dave walker said when he mapped them they ran 100% cycle at 200bhp so said i should use the K-series ones to get that little bit more and still run a sensible duty cycle

[rob_e30]

I strongly recommend the RC Engineering website as they have a great tool for calculating injector flow http://www.rceng.com.  We're running 750's and didn't exceed the duty cycle until 27psi.  At lower boost levels running about 60% duty cycle.