Author Topic: educate me about turbo (Read 9875 times)

oldtimer · « **on:** October 22, 2007, 07:28:52 PM »

Just have a couple of question about force induction (turbo) so I have some basic idea about setting a system up for my 1991 318is.

I have seen several photos of other set up. One question is. Is the MAF gets eliminated? If so how is the air flow gets metered?

Do I need to change the ECU for better management?

The stock throttle body. Will it work with turbo application?

For the most part I can manufacture the exhaust manifold to meet my need to put together a system.

Which turbo is best to run with? T3 or T4.

What size tubing is best for the application?

How about EVO turbo?

There are several pictures of other members turbo. Most of them show the tubing being hooked up directly to the throttle body without the MAF in play or I did not see it in the photo. Thank you for any inputs. If I missed any other critical parts I need to consider please share them.

I consider myself �old school� meaning big piston, high lift cam, high rise intake manifold and big carbs for power. Now this days �turbo� is a house hold name now so I thought I would give it a shoot in putting together one.

Has anyone used the intake manifold from�666fabrication�? Does it come with it�s throttle body?

haledj · « **Reply #1 on:** October 23, 2007, 03:01:17 AM »

Quote from: oldtimer;36338

Just have a couple of question about force induction (turbo) so I have some basic idea about setting a system up for my 1991 318is.

I have seen several photos of other set up. One question is. Is the MAF gets eliminated? If so how is the air flow gets metered?

Do I need to change the ECU for better management?

The stock throttle body. Will it work with turbo application?

For the most part I can manufacture the exhaust manifold to meet my need to put together a system.

Which turbo is best to run with? T3 or T4.

What size tubing is best for the application?

How about EVO turbo?

There are several pictures of other members turbo. Most of them show the tubing being hooked up directly to the throttle body without the MAF in play or I did not see it in the photo. Thank you for any inputs. If I missed any other critical parts I need to consider please share them.

I consider myself �old school� meaning big piston, high lift cam, high rise intake manifold and big carbs for power. Now this days �turbo� is a house hold name now so I thought I would give it a shoot in putting together one.

Has anyone used the intake manifold from�666fabrication�? Does it come with it�s throttle body?

most of your questions can be returned with "how much power do you want to make and how much money do you want to spend?"

the 666fabrication intake manifold- from jon volk's site"Just about any throttle body flange can be accomodated. Mustang style is standard as this will allow for many throttle bore variations."

as far as metering air, I have only used megasquirt, a DIY aftermarket ECU, that uses Manifold air pressure for fuel calculations.

rob_e30 · « **Reply #2 on:** October 24, 2007, 01:03:27 AM »

I'll try and answer some of your questions as quick as I can...

Questions 1 & 2 go together... I replacement ECU is the best way to go and allows you to eliminate the MAF by running a MAP (Manifold Air Pressure) sensor. It allows more flexibility in tuning and perhaps running other devices (water injection, boost control, etc.)

Stock TB can be used, but the shape makes it tough to plumb the system. I think it's restrictive as well.

If you can weld really well and have the tools you can fab up a manifold, but there is a fair amount of science and work in creating an equal runner length (tuned) manifold. A log is easier but much less effecient, especially with a 4 cylinder.

I'm not sure you can get enough displacement in an M42 to justify a T4 turbo.

Tubing size depends on a number of variables as well as which part of the system you're talking about. Pick up "Maximum Boost" by Corky Bell for info on manifold, intercooler, and exhaust plumbing.

Can't comment on the Evo turbo as I don't know what it is or how big.

Now that I answered your questions, here is an off the top of my head list of the decisions you'll need to make for a full turbo build. For some you can say "Keep it stock" but you still need an idea of what you just decided.

Stroke, bore, compression ratio, CAM lift & duration, valve size & spring type, rev limit, spark plugs, injector size & type, fuel pressure, fuel flow (pump), ECU, intercooler size, intake plumbing, throttle body size, oil cooler & plumbing, radiator size, exhaust manifold type, material and tubing size, exhaust pipe diameter and routing, BOV & waste gate springs, O2 sensor, instrumentation, waste gate/boost control, internal/external waste gate, turbo flange, exhaust flange, turbo size, trim, and A/R, oil return to block/pan, clutch and flywheel. PLUS all the mounting, plumbing, and routing decisions to make it all fit and work.

Then you have to find the parts and put it all together.

FL318i · « **Reply #3 on:** October 24, 2007, 09:46:01 AM »

Quote from: rob_e30;36448

Now that I answered your questions, here is an off the top of my head list of the decisions you'll need to make for a full turbo build. For some you can say "Keep it stock" but you still need an idea of what you just decided.

Stroke, bore, compression ratio, CAM lift & duration, valve size & spring type, rev limit, spark plugs, injector size & type, fuel pressure, fuel flow (pump), ECU, intercooler size, intake plumbing, throttle body size, oil cooler & plumbing, radiator size, exhaust manifold type, material and tubing size, exhaust pipe diameter and routing, BOV & waste gate springs, O2 sensor, instrumentation, waste gate/boost control, internal/external waste gate, turbo flange, exhaust flange, turbo size, trim, and A/R, oil return to block/pan, clutch and flywheel. PLUS all the mounting, plumbing, and routing decisions to make it all fit and work.

Then you have to find the parts and put it all together.

i think u just scared the crap out off him....LOL!!!

vatos_p · « **Reply #4 on:** October 25, 2007, 05:40:09 AM »

check the forum , many turbo applications have been done , i am one of them...stock ECU with biggyback instaled , stock engine , stock intake , stock compression , 0,5 bar pressure , 200 hp

oldtimer · « **Reply #5 on:** October 25, 2007, 05:56:03 AM »

No, I did not scared it definitely verified that I need to completely retire so I can play with this type of things. The care I want to turbo is my daily driver having been to use to driving more powerful car (Boxster S) but enjoy driving my vintage E30 I want to have the power when I am driving on the highway with a huge group of poeple who drives like an old lady. All this inputs have help I have gathered a lot of infor to determined the system and located majority of the parts. The engine is out of the car so I am able to simulated the exhaust for fabrication. Oh yeah I have managed to acquire a "mandrel" tube bender and a miller syncro 250 to fabricate most of the tubing. For now I am shooting for a stock engine to be turbo when I can spend more time in addressing all of the parameters mentioned I will do that to my other E30 which is prep for a larger engine (V-8) my son's idea.

The final HP I am shooting for is doubling the stock HP. So I guess around mid to upper 200's.

vatos_p · « **Reply #6 on:** October 25, 2007, 06:50:20 AM »

with a set of forged pistons , new head flange bigger to drop compression to 9:1 you can go 1,2 - 1,5 bar of pressure , and go about 340 - 400 hp..
so if you have the engine out , it is easy to change these things..

FL318i · « **Reply #7 on:** October 25, 2007, 08:31:51 AM »

definitly drop compresion, im gonna use stock internals with new pistons just to run 8psi for DD, im still debating the engine management, can the stock ecu be used for 8psi?

rob_e30 · « **Reply #8 on:** October 25, 2007, 10:49:39 AM »

One of the biggest issues with the stock ECU is that there is no knock control. You can try and tune it out but you're leaving HP on the table and have no protection against bad gas or higher ambient tems that can cause problems. I'm not that familiar with the piggyback systems and how they operate. The ideal setup is something that integrates a MAP sensor in place of the MAF and can be tuned for your specific injectors, fuel pressure, O2 sensor, and desired ignition at a specific RPM given other variables like engine temp, intake temp, throttle position, and amount of boost.

The problem with an aftermarket ECU (aside from cost), especially one with a MAP sensor is that it won't pass inspection in most states.

Abrax · « **Reply #9 on:** October 25, 2007, 02:56:42 PM »

Hi,

I've just collected all the info needed to build my M42 turbo project.

I would say - consider VEMS / http://www.vems.hu / it is similar to Megasquirt and has knock controll and even EGT /exhaust gas temperature/

To double the power - I'd say That You have to do following:

Change the injectors or add second set of them into the system :-)

Go T3 rather than T4 /as said before too less exhaust gases to run it early enough/ T3/T4 is capable of doing 260-280 HP in this car /as it is shown in some cases for example on http://www.e30tech.com / Anyway I would definately recommend Holset HX 35 from scania truck.

Lower Your C/R, but You don't really need a new set of forged pistons. Stock should do the job, but You have to lathe them to lower C/R. The line on the picture shows how much to lathe the piston :
http://www.e30.kamieniwnetrze.pl/turbo_m42/piston.jpg
I didn't measure it but it should give You about 9.5 : 1 C/R with stock headgasket. Replace it with 1mm headgasket and You are close to 9:1 :-) This is really enough, but the intercooler needs to be really efficient and You should have knock control. The higher the C/R the more responsible is the engine, but You have to avoid detonation at first.

Stock internals /crank, rods, even cams/ will do the job pretty well, but You have to keep in mind that You really need good intercooling system and low restricting exhaust pipes. On stock cams M42 is capable of doing 300HP with 1,5 bar of boost.

Of corse to keep it safe, You have to tune the turbine to get You the power near the red line, because the torque will not be too large if done so. On the other hand You probably could go 300HP's with 3000 rpm's but the torque would definately hurt Your stock internals.

throttle, intake manifold - keep theese stock - they will do the job for 300Hp's for sure

I'm worried just about the inspections... The car has to be street legal... So You will have to recalibrate it to pass emission tests...
But it is generally possible to manage Your 4 injectors with 2 different maps, one for economy and passing tests and the other for the performance.

Corky Bell's book "maximum boost" is really nice, but I would strongly recommend Jeff Hartman's "How to tune and modify engine management systems" it gives You more specific info :-)

GOOD LUCK!

strypt · « **Reply #10 on:** October 25, 2007, 03:37:04 PM »

I would definetly not recommend to lathe the original pistons, a couple of M42 turbos here in Sweden has done just that and all have failed their pistons in the area between the top of the piston and the first piston ring.
I believe they were running 1-1.3 bar boost and used a standalone ECU tuned the proper way. I would rather go with forged pistons or a Cometic MLS 3mm gasket.

One alternative could be using pistons from another engine with the same bore, I'm using pistons from a M54B30 engine which has got ~3mm lower compression height than M42 but with a flat top instead of a negative dome. They will lower the CR to about 8.2:1. A bit low for my taste but they'll have to do as I'm only building this engine to test if I like the concept of M42 turbo and circuit racing. I would not recommend this if you're going 1+ bar.

rob_e30 · « **Reply #11 on:** October 25, 2007, 11:04:15 PM »

I can tell you from my personal experience that a T3 would be too big for a stock displacement and you won't get more than a few pounds of boost at 3K. You might want to learn to read compressor maps and there are some guys over at Bimmerforums that have put together some good tools. My guess is a GT2860 would be a good choice for stock internals, would handle 10-12psi nicely, and put down about 230 RWHP. The VE of the stock heads falls off after about 5K RPM so torque will fall but HP will continue to build. I would not worry about it as a daily driver but we definitely need a major head rework for the race car.

For a daily driver, it's not about the max power but about the range. In this case, I would be willing to trade and use a smaller turbo for a more responsive and broader power curve.

ApocolypseAutoEngineering · « **Reply #12 on:** October 26, 2007, 12:26:38 AM »

I'm hoping to put down just over 200 at the wheels myself. Now if you want reliability with umph ask yourself if you want topend or low end power. All this could be set by good gearing.

rob_e30 · « **Reply #13 on:** October 26, 2007, 11:54:32 AM »

One thing to keep in mind that a turbo setup should product more torque than HP. If you want that feeling of "umph" when you get on the gas, it's torque. Worry less about the peak HP and more about a broad torque curve.

Abrax · « **Reply #14 on:** October 26, 2007, 12:50:39 PM »

My idea was to go with high end power, which is much safer to the pistons and letting the engine breath well /by constructing low restricting exhaust system and digging the head little bit/. Combined with high octane gasoline and very efficient intercooler should let You 300HP's near the red line still not damaging the pistons lathed to give C/R about 9:1. Of corse latheing stock pistons is not really best way of lowering C/R but it should be durable enough with 0,8 bars or something about 1 bar... But it must be near 5000 rpm's, because in the other way heat and pressure will destroy theese stock - not forged pistons. If You need high drivability with whole rpm's there are better ways of achieving this - rob You know the work well ;-) But for demonstrating the power from time to time, high end power system should work nicely to compete potentially stronger cars.

I hope it will work well ;-) The idea of latheing stock pistons came from... Sweden :-) Mattias Sandgren has put this photo somewhere on the e30tech forum while discussing low cost turbo setup.

For acceleration car, You can have bigger turbocharger despite it will not even start producing boost at 3000rpm's... The better as I think, because You still have economical car below the powerband ;-)

But think it once more. Your engine will work just in the way that You will design it.. And it is not said that it should give You flat torque through the whole rpm's to be nice and driveable... It depends on what You really need.

Me personally like the most idea of the high end high reving turboed engine, but it is not the engine for comfortable everyday use.

strypt:
Do You know other info about theese damaged piston engines setup?
I mean what turbochargers they used and if they were low or high end power?