M42/M44 ITB Kit Design

[Jaker]

Excellent news. Really looking forward to the results. Hoping for a significant improvement!!

[lambertius]

So yesterday ended up being a bit of an annoying adventure. The guy with the hub dyno ended up misrepresenting a few things about pricing and tuning so I had to bail on my plans. I ended up spending most of the day trying to find new quotes for an exhaust and dyno runs. I ended relying on one of Rama's friends for the Dyno run - apparently not accurate (supposedly off by 10%) but reliable (gets the same results every run). So I can't say for sure if the power is exactly what the car makes, but I can say whether or not there is a gain or a loss. Because is is much cheaper, I will do runs between every upgrade!

Perhaps someone here can help me?

Apparently there is reasonable power to be had changing the exhaust - in particular the muffler with the M42/4 engines? Does anyone have any experience with this?

From what I can discern, even if the exhaust is the same diameter a sports exhaust is enough to unlock some power - does anyone know if this is to be true? I've been told a few times, that for the engine displacement, a 2.25" exhaust would be as large as one should go, so I'm wondering what people have done regarding exhausts, and what noise/performance they saw?

Anyway some picture!



The assembled kit (getting installed today)



The Dyno results. EDIT I graphed the results incorrectly and have since corrected them

Some notes on the Dyno

• I compared it to my friend's car (different dyno and time, 2001 Honda Prelude 2157cc) just out of interest.
• The results do clearly demonstrate the DISA actuating - as well as the engine 'choking' above ~4750RPM, which are all things that I experience while driving.
• The car was totally stock during this run.

EDIT: Rama got the car running today, and there is a short video of it on his facebook! https://www.facebook.com/rama.rhdengineering?fref=ts Just have to get the airbox done and back on the dyno!

[Barrosco]

I don't have any experience with the stock exhaust system as my 318is came with an 2.5" aftermarket system when I got the car. I can say that for a stock engine, the 2.5" is definitely too large. I've been playing with different layouts the past few weeks and found that the 2.25" is much better suited to an internally stock street car. Bottom end response is much improved and by going by the mileage displayed on the econometer, it takes the engine much less effort to get up to speed. The upper end of the rev range feels like it may have suffered a little bit, but that's probably placebo because with the oversized tubing there was no bottom end power and then it suddenly jumped into the power once it hit 4-5k rpm. I wouldn't be surprised if the stock exhaust was much more restrictive, but I'm not the person to be able to give you any factual data in that respect.

Looking forward to seeing this kit go up on the market. I've been debating between Rama's kit and the Dbilas race kit, but I've been wanting to see what kind of results you guys end up with and what the pricing is going to be like. Also looking forward to seeing all of your findings throughout this process if you're still planning on publishing that.

[lambertius]

Yeah I will be, I have a 5000 word monstrosity plus simulation results which I wrote a while back, but I decided to hold off till the whole kit was completed!

What you're saying seems to confirm some things that Rama and I suspected, as well as other rumours I had heard. For the displacement, we thought that a 2" exhaust with a sports cat and muffler would be more than enough, since the car originally has a 1 7/8" exhaust and restrictive exhaust and cat. I had read people bitching about 2.5" and even some about 2.25", but as usual no dyno results.

Because its so expensive I want to have at least an idea before I go for it. My two options were to go to a full 2.25" system, or used the current system with a new muffler and cat. I thought I would get some ideas, and wait to see what the results are for the itb kit. If the kit behaves as it should and opens up the top end, I'll go to a 2" exhaust which should free the top end a bit more - but if there is a significant loss in the low end, then I would keep the stock diameter otherwise I would risk dropping it further. Anyway, thats what I'm thinking. We should know in a couple of days

[Darky]

Hi

Nice itbs

I received my car rhd e30 318is with a stock engine but chipped and with twin 2 inch.
Again it suffered down low until it got to at least 3500 rpm
But then I changed to a twin 1.75 this improved bottom end dramatically, top end there was little change.
However While doing this I noticed the shocking rhd e30 m42 exhaust manifold and after adapting a lhd manifold and getting rid of steering knuckle there was a large improvement across the rpm range.

Hope this helps
Rohan

[wazzu70]

I don't think the cat or the tubing diameter is restrictive. Like most systems the OEM muffler is the problem. If you just replace that, you will be in good shape IMO.

[lambertius]

Thank for the feedback guys!

I went and had a fiddle with the car today and got a clear video of it running.

We're still working out the throttle position and making the intake plenum. There are a few little things to work out, but for the most part the factory ECU seems to handle running without the MAF quite well considering the difference in components! Should be back on the dyno early next week!

https://www.youtube.com/watch?v=8SB5N4OrAX4

[Warsteiner]

+1 for wazzu70.

My experience with the S14 shows the exact same thing unless you're doing a stroker motor. My stock S14 motor with just a chip, colder plugs and a muffler gained 22HP at the crank. I then changed to Schrick cams with nothing else and gained another 24HP at the crank. So the engine went from 192HP to 238HP with cams, plugs, chip and a muffler on an otherwise stock internal motor. I did this all on the same dyno too. Keeping the stock exhaust with header and swapping mufflers to something less restrictive is the biggest bang on the system. I'm guessing the stock M42 header can handle at least 205HP at the crank but that's about it. Then you'll need something bigger.

So.....any muffler other than stock will most likely help it breathe better. Opening up the exhaust too much without the rest will def change how the car drives in your rpm range. Remember that the head is still between the ITB's and the exhaust. (Compression and cams play a huge role). Removing the MAF or AFM is the biggest and best thing you could do to a stock motor and will definitely have a large improvement all around but not enough to change your pipes to a larger diameter just yet without any other internal changes. Tuning will be very important. This is just my opinion and observation as well as testing all these years on the S14 and now on the M42.

I think this a phenomenal job you're doing with this project lambertius!!!

Cheers,
~Ralph
M42 Stroker 2.045L with ITB's and a 666Fab header with E30M3 exhaust and a bunch more....LOL
Heading to the dyno for a complete tune 4/28/15. Looking for great torque for street driving not high HP numbers. 250* w/ 10.3mm lift Cams will be the limiting factor for HP on this motor.

[lambertius]

Thanks Warsteiner! Its more or less what I thought, so its good to have someone talking about actual results.

This kit will actually be able to run off the MAF, and I will be running mine off the MAF for a number of reasons (I'll elaborate in a later post). At the moment the kit is fully fitted with the throttle linkage all working, the only thing that it is waiting on is the intake plenum. Rama has been working on it for a few days so that he can replicate it for sales later.





The dent in the back of the box is required to clear the wiring loom. Unfortunately in our efforts to get the straightest possible intake track, it impinges slightly on the loom bound under the window scuttle. Fortunately it is only a tiny obstruction so other than being a fiddly design effort for Rama there will be nothing wrong with it. It won't infringe on the trumpet.

[lambertius]

Some Progress Pics

[MLM]

Nice work! Is there going to be a carbon option haha.

I have a 2.5 exhaust and dont suffer from torque loss. I changes alot of things (including equal length RHS headers) in one hit so cannot offer specific exhaust only results. Ralph though is correct IMO when he says the head is still the bit in the middle and from my experience and advice from tuners the exhust flow at the head is what impedes the engine and the resultant numbers. Your process of testing I think will put alot of this to rest and i look forward to your results.

Keep it up

[lambertius]

Yes it will be available in CF

So, here are a few things:

• Fully installed and running today - not an ideal fitment yet, but that will come after fit is verified
• The stock ECU is learning the setup - from when I first started the car till I got home the power difference was substantial
• It hasn't visited the dyno yet, but will tomorrow
• I can conclusively say that ITBs wider than 42mm even for a racing version of this engine with nutty cams is seriously overdoing it
• Unless you have a power band from 6000-8000RPM make sure your intake length is at least 13"

Today driving around the power differences are truly perceptible, but the actual values need to be confirmed on the dyno - I'll elaborate more when I have numbers, but tomorrow we're going to lengthen the intake as much as we can with the space in the engine bay to try and get the most out of it. It is behaving as expected, but its not tuned for the right range yet.

The difference to the power curve is substantial to the point that its obvious without the dyno, but it will be good to have actual numbers. The power curve has flattened out massively, but its still climbing by the time I hit the rev limiter so the trumpets are still too short. I can say though from this experiment, that there is no reason to go for bigger ITBs for this engine - even the sim data I have (which I will bring to the surface eventually) showed that 42mm ITBs could handle nearly double [Note, this number is still under revision] the airflow before they cause as much drag as the stock manifold.

The solution hasn't been reached yet though, but hopefully we get the lengths right and get some more power!

[wazzu70]

Fantastic!!

[lambertius]

Who wants to know the Dyno results!? Yeah, me too...

Yesterday the engine was running fine, and I've driven about 150km since the install, but the power band was way too late to be useful so today we extended the length of the intake to pull the powerband back into a useful range for a street user like myself (for a racing guy you would be ready to roll methinks). It starts pulling superhard at about 5500rpm, which is totally useless on the road, because you change gear a second later and you're back out of the power band... Anyway, my point was the engine was running fine, but not ideal so we popped off the airbox and extended the intake by 60mm for the dyno run and reassembled it, and the car just wasn't running at all so we missed the dyno run today.

Considering there are no electrical components in the trumpets and airbox that we made, we suspect that there was an extremely unfortunate coincidence that the Crank sensor died at the exact same time for absolutely no reason related to what we were doing. *sigh* Hopefully that is all it is so we can replace the part and get it back on the dyno tomorrow.

We're pretty sure that is the case, but if anyone has experienced the following before please share!

• All other functions as normal (engine cranks over, fuel pump injectors etc)
• Engine will not fire
• During cranking the fuel pump, injectors and coils aren't working (this seems consistent with the crank not 'seeing' the engine rotating - we tested the components all individually)
• Our scanner saw zero rpm during cranking
• Resistance between pins 1-2 and 3-2 on the CPS ~600 Ohms, while I'm lead to believe it should be 1k (If someone knows the answer to this it would be extremely helpful)
• No engine error codes

The engine is acting as if it has been immobilised, and though we're pretty sure it is the CPS (already have a replacement on the way) it would still be good to know if someone has had a similar experience. EDIT: If anyone wants to know for future reference, the above are the symptoms of a failed Crank Sensor

So yeah, I'm still not sure of the results yet. I can say for certain that it was down on power for a while, but I'm really quite impressed how the stock ECU learned the new setup - I reckon that there was at least a 10% improvement in power from when we completed the install to when I got home. The problem though, is that the power is coming on at 5500RPM which is just too late to be useful - the stock setup exists purely to generate torque as early as possible, which is does extremely effectively at the cost of choking out the top end as you can all see in the early dyno results. However, 5500RPM is too late as when you shift you're back around 4500RPM so you're out of the powerband. We've done out best to extend the intake into every available space in the engine bay to see if it will have street applications at all. When it comes on though its a real kick, you can tell there is more power (and its still pulling till the redline, definitely room for many more RPM). The other thing is the power delivery is very linear, not the hard rise of the DISA and then flat from the mid-onwards. I think that if we can get enough length to get the power on from that 4000~4500RPM point then we can make more power than we lose, and make the kit viable for street use, otherwise it will probably be a racing only setup for strokers and cams. I did learn from this that absolutely, other setups with large ITBs and short runners are the wrong way to go - and I haven't even gotten it on the dyno - for any M42/4 setup, and if it is a street setup  you would absolutely be losing power. I have a whole bunch of theoretical stuff I wrote in Jan for this thread, but I've been holding off it till the dyno results so that I could support my points though everything I've experienced since then has confirmed my findings. Hopefully we will get some results tomorrow...

Some pics of the short setup, we added another set of 50mm spaces + a 10mm spacer, and if we can get it running tomorrow, we will try another 15mm of trumpet length inside the box!

[lambertius]

So who wants to guess how it went?

https://www.youtube.com/watch?v=0nysqbIuXJY

Is 42mm ITBs really to small, is 15" intake too long?