Author Topic: M42 stock limits (Read 13132 times)

kaliE36 · « **on:** October 01, 2006, 04:49:09 AM »

Hello everyone,
if i understood well, the M42B18 engine have all internals forged (crank + con-rod + pistons) ..
i wonder if this engie can handle with 1.2bar boost (18 psi) - with stock internals but with lower compression ratio of 8.0:1 (using a 1.5 mm thicker head gasket)
the setup that i intend to make is a TMS (turbo mechanical system): cetrifugal s/c for low's - mid's revolutions and a large turbo (Garrett T30-35) for high rpms range ... expected power: 300bhp
thank you,

asubimmer · « **Reply #1 on:** October 01, 2006, 12:19:00 PM »

its going to depend on your miles, but I think its very possible for you to run those #'s if you are properly tuned.

edit: I ran those #'s for you and you are prob looking at about 280hp w/ stock bore and stroke. With s52 pistons that would bring you up to your 300hp goal, almost exactly.

sheepdog · « **Reply #2 on:** October 01, 2006, 10:42:25 PM »

Should be capable of taking that.
You will need a custom cam, ported head and an aftermarket ECU. I also would not count on pump gas.

One thing though, a few companies, including Audi have tried mulitple forms of supercharging like this and had a very rough go of it (I.E. failed). How are you planning to deal with the changeover between the differnt forms of supercharging?

Also, why a centrifugal if you want mid (I tend to think of them as the lowest form of S.C.), a twin-screw would be better and provide a much wider range of useable power from low to semi-high. For street, you would be better off all around with a twin screw due to simplicity and operating range.

Also, why 2 forms in the first place, a well done turbo should be capable of around a 4000 rpm range. Which should be plenty on a car that only goes to 7000rpm.

I think you are making it more complex than it needs to be. Then again, 300 without lots of lag is asking a bit much from such a small engine.

Another option to consider is stroking to 2.1liter, then add a supercharger of one form or another (even the D.A.) should be able to reach 300hp with little lag, and have a better bottom end.

Euro Nation · « **Reply #3 on:** October 02, 2006, 01:04:14 PM »

Straying from the original question, I too will put out a few things about twincharging. But to get the original question out of the way. I don't know of anyone, or at least anyone who's talking, that has had a mechanical failure in the M42 with proper tuning due to excessive power via forced induction. I was hoping to be the first

Now on to the show:

A GT28RS will pretty much take care of all the things you want. A GT2871R will spool a couple hundred RPM later and take you to 350whp.

Twincharge systems are only worth it in a few situations:

You're going to be making a BIG number. Like 450 and up. The turbo you need would have a very high boost threshold and at that point it would be very beneficial to have a larger turbine housing which would only hurt more. So you add a supercharger for bottom end and cheat the system. You have boost down low, you're adding a pressure ratio to the engine and cheating the turbo into thinking you have more displacement (8psi on a 1.8L flows as much air as a 2.8L) and EGT goes up which helps spool.

You have too much money, time, or you have the parts laying around for no reason.

As for your charger... a centri blower is the LAST choice. They spool up like a turbo. They aren't fixed displacement which means air can travel through them at will. I don't even want to think about the math with the thermodynamics involved. I can do it but it would be a waste of my time. Basically the best application for this would be to blow the supercharger through the turbo and multiply the pressure ratios. You could make a hell of a lot of boost this way but it isn't going to spool any sooner... and you can get enough boost off of one compressor to blow an M42.

Twin-screws are a great choice for supercharger only since they have a low boost threshold and are almost as efficient as a turbo. You can run 25psi with a twinscrew with reasonable efficiency and eliminate the turbo but the problem there is the 40+hp of belt loss in trying to spin the damn thing so hard. The downside; these little bastards are expensive and only available through a couple sources (Lysholm, Opcon Autorotor and Kenne Bell). If you're going twin then there's no reason to pay for the extra efficiency at high boost since you wont be using it.

That leaves roots. Eaton blowers are great, they're cheap, they're available in all kinds of OEM applications. $200 will pick you up one on ebay. They'll last more than 100K miles. And guess what... someone makes an Eaton based kit for M42s. I wouldn't try to take one above 10-12psi since their 55% adiabatic efficiency is too poor and even intercooled you're putting a lot of heat into the engine.

If I were doing it I'd start with a DA supercharger kit and a 60 trim T4 with a fairly large turbine. I've run that turbo and ones like it on a 2L before and NOTHING happens before 3700-4000rpm. Adding a supercharger would do wonders. Of course with this kind of setup I'd better have my eyes set for 450hp.:cool:

EDIT: Oh yeah.. don't forget to intercool the hell out of it. The only good place for an intercooler is between the turbo and the supercharger so that inlet air going into the supercharger should be damn cold.

sheepdog · « **Reply #4 on:** October 03, 2006, 01:38:31 PM »

I still think a Metric Mechanic 2.1 stroker with the Downing Atlanta supercharger would be the best way to do 300hp.

This would get you a fresh, well built motor, and a lower boost requirement.
Not to mention a lot simpler setup than any dual system.

Euro Nation · « **Reply #5 on:** October 04, 2006, 08:04:15 PM »

You do realize that an MM 2.1 with a DA supercharger is, at a bare minimum, a $10,000 affair right?

I'm reasonably certain I could make 300hp with half the money and that includes rebuilding the engine.

The other problem is that the DA supercharger isn't capable of 300hp. You can bolt it to a 3L... it's still only going to move a certain amount of air.

Alpine003 · « **Reply #6 on:** October 04, 2006, 10:25:24 PM »

A local guy is running twin charge on his MR2 running 11.7 1/4 and making around 350hp. Not bad for the displacement.

sheepdog · « **Reply #7 on:** October 05, 2006, 12:50:05 PM »

Quote from: Euro Nation

You do realize that an MM 2.1 with a DA supercharger is, at a bare minimum, a $10,000 affair right?

I'm reasonably certain I could make 300hp with half the money and that includes rebuilding the engine.

The other problem is that the DA supercharger isn't capable of 300hp. You can bolt it to a 3L... it's still only going to move a certain amount of air.

Probably will be around $10k, but what is being proposed is not going to be cheap in the end either. Any idea how hard tuning a dual supercharged engine will be? Ask Audi.

You may make it for $5k. I (really) doubt it, but just maybe. If you know the right people to help, know a ton yourself, and have lots of friends who can score you some really good deals. One small problem or 2 and you are going to easily going to be at the same price.

Think about it, most rebuilds are a few grand, yes, you can do it yourself. However, a lot needs to be done by a pro with a machine shop. Parts for a rebuild are not all that cheap. Plus tools to do it properly.

Then there is the blower. Got a killer deal on that? Roots, yes, you can go cheap. Get a bad one though and lot of money has already been wasted.

Turbo, may as well rebuild that too before you start.

Put it all together, then start in on fueling and ignition. Megasquirt is the cheapest. In the end, expect AT LEAST a grand. Need somone to tune it, expect good money.

Various systems, something that will be lots of fun. Making both systems work will be a nightmare, unless you wimp out and go one into the other, which is honestly, not a good thing to do. Regardless you still need intercooling, larger radiator, exhaust, injectors, fuel plumbing and such. Then there is tuning itself, getting agood fuel map on this will be an utter nightmare, even for a professional. If your intake system is funky, expect even more costs.

Any small mistake, could self destruct the entire system.
Then you start from scratch.

As for the D.A. supercharger, yes it is capable of 300hp. Especially you do a pulley swap. That supercharger has been shown to be capable of 280hp and more. Look into Mini superchargers.

Think about this, how much is all of this going to add to your front end? Turbo system, blower, intercooler, etc... Not to mention heat.

Speed costs money, how fast can you afford to go?
A much easier and cheaper method than all of this is either start with either an M10 or M20 engine. Or better yet, an SBC. In the end, the weight will be the same, or less, and be FAR cheaper than trying to go dual supercharged on an M42.

sheepdog · « **Reply #8 on:** October 05, 2006, 01:03:04 PM »

You guys are missing a lot if you think you can make this a driver for anywhere close to $5k. You may get the engine and the blowers, but honestly, I do not see how you can expect to get a running car you can drive for that.

Yes, doing it the way I suggested will be expensive, probably $14k by time time all is said and done. However, in the end, you could drive that car across the country, race it and do what you want and bot worry about it blowing up. You could daily drive it and get 100k miles out of it.

Sorry, a backyard engineered setup like what has been described, will not do that.

You will be dealing with far more issues than the method I described. Tuning alone would be a nightmare, you need an entire new fuel system. Then there is turbo pumbing and cooling, then blower plumbing and routing. Underhood heat to deal with, engine cooling issues, WEIGHT issues. may also want to consider a beefed diff and better brakes.

Can it be done, yes. Cheap, yes, but for $5k, I highly doubt it will look or run respectably, much less be reliable.
If you want a car to drive only at the strip, on race gas, maybe, but a daily driver it won't be.

Euro Nation · « **Reply #9 on:** October 06, 2006, 07:34:25 AM »

I think you missed something. I'm not advocating twin charging and for $5000 I have no intent in utilizing such a system. I'm of the single turbocharger mind set. Nice to see you're in such a hurry to try to prove me wrong though. Sucks you typed all that out to try to end an argument no one started.

I still think that spending $10K+ on making 300hp in a $3000 car is idiotic.

Author Topic: M42 stock limits (Read 13132 times)

kaliE36