Author Topic: Larger throttle body? Info? Power gains (Read 16984 times)

ose30 · « **Reply #15 on:** June 08, 2007, 12:40:31 AM »

Quote

Megasquirt is much better. For the price if you wanted to remove the AFM just megasquirt it, will be cheaper and work better then any other MAF hack.

If you would like to remove AFM, It's easier to use piggy pack like Link Electromotive's AFM Link or Intercept Link boxes.
Also Perfet Powers SMT6 will do the trick. With these boxes you can use either MAF or MAP sensors.

e9nine · « **Reply #16 on:** June 08, 2007, 01:44:53 PM »

While Megasquirt is a good option. It is not for many.

I have seen and ridden in megasquirt cars of various flavors but not on an m42.

Road tuning, then dyno tuning are the longest arduous tasks. I would also not suggest doing this to a daily driver car unless you have a fully functional base map and A LOT of time to tune. The most optimal megasquirt settings will take a while to attain.
Factor in the cost for Megasquirt, Dyno time and tuning time as your 3 variables.

G.luck.

gearheadE30 · « **Reply #17 on:** June 08, 2007, 03:13:35 PM »

Quote

If you would like to remove AFM, It's easier to use piggy pack like Link Electromotive's AFM Link or Intercept Link boxes.
Also Perfet Powers SMT6 will do the trick. With these boxes you can use either MAF or MAP sensors.

WIll either of these piggybacks work with a chip, say a markD chip, instead of requiring a bespoke chip to interpret the new signal or acting as a chip? I'm assuming that they don't. I looked at the SMT6, isn't it similar in concept to MS?

ose30 · « **Reply #18 on:** June 08, 2007, 04:06:46 PM »

All of these boxes will work with most of the chips available. I have used AFM Link installed to Porsche 944 Turbo with several different chips without problems. SMT6 is a piggback box and cannot compare to MS. I prefer VEMS, which is better than MS. You can tune also VEMS with Megatune.

Alpine003 · « **Reply #19 on:** June 08, 2007, 07:11:28 PM »

Quote from: e9nine;27410

While Megasquirt is a good option. It is not for many.

I have seen and ridden in megasquirt cars of various flavors but not on an m42.

Road tuning, then dyno tuning are the longest arduous tasks. I would also not suggest doing this to a daily driver car unless you have a fully functional base map and A LOT of time to tune. The most optimal megasquirt settings will take a while to attain.
Factor in the cost for Megasquirt, Dyno time and tuning time as your 3 variables.

G.luck.

+1
I fully agree. In addition to dedicating a LOT of time to part throttle maps in various situations, one will also need to invest in wideband and egt to do it "right" to be able to obtain the most efficient and refined street map.

I've tried to do it on a previous car and I would say I was only 75% successful and had a long way to go before I ended up selling it.

johna · « **Reply #20 on:** June 09, 2007, 02:08:03 AM »

Quote from: rsafier;27331

From my understanding the TB and a M30 AFM are both worthless mods. There really isn't much of a restriction on the intake side of things. If you were to compare opening surface area on the TB I am pretty sure its equal to the M20 TBody, just 2 throttle vales instead of one.
The M30 AFM on the M20 is a mild improvement, but nothing radical.

The smaller butterfly is 35 mm across and and the second is 54 mm across if that helps work out the difference.

bmwman91 · « **Reply #21 on:** June 09, 2007, 02:26:50 AM »

Quote from: Alpine003;27318

I just can't see how a bigger tb on the M42 can benefit as long as there is the barn yard door ahead of it.

Not true. I did a MAF conversion on mine and saw NO power gains. From looking at datalogs of flow data, no more air flows with a MAF. The trap door would intuitively seem restrictive, but it is not. It is perfectly fitted to the motor, and elimintaing it does nothign for power. Sucks, but it is true. The M20 responds well because the meter was badly undersized for it.

Quote from: tjts1;27326

+1
Has anybody megasqirted on of these engines yet?

Yes. Pain in the ass, and it did not really give much more power. Fun project, and better throttle response (same with a MAF), but nothing more really on a stock motor.

Quote from: rsafier;27331

From my understanding the TB and a M30 AFM are both worthless mods. There really isn't much of a restriction on the intake side of things. If you were to compare opening surface area on the TB I am pretty sure its equal to the M20 TBody, just 2 throttle vales instead of one.
The M30 AFM on the M20 is a mild improvement, but nothing radical.

The AFM itself really isn't that bad as far as being a restriction, its biggest issue is the delay in throttle response.
I know there is at least one turbo M42 that is running MS. I know from my M20 experaince the throttle response on Megasquirt is much better. For the price if you wanted to remove the AFM just megasquirt it, will be cheaper and work better then any other MAF hack.

One thing I am working on is making a pulse manifold like Metric Mechanics sells for 1K. I have a spare intake and got the price from a guy to do a prototype, about 300. I might just do some of hte work myself for the 1st one. MM claims 15% increase in low and midrange torque

Very correct. I am actually very interested in the pulse intake manifold technology. What will you be managing your motor with? I cannot imagine it will run right at WOT with this drastic of a change (though I can always hope).

I KNOW people here have ported the TB. I have a machine shop to do it in should I want to. Did it do anything for you? Thanks.

ose30 · « **Reply #22 on:** June 09, 2007, 02:48:06 AM »

Quote

Not true. I did a MAF conversion on mine and saw NO power gains. From looking at datalogs of flow data, no more air flows with a MAF

Have to disagree with You. We have dyno tested Porsche 944 Turbo first with AFM with AFM LINK piggyback box and after that the same system with Bosch MAF. We used the same chip and same boost. we got over 20 dyno proofed additional horses. Of course with N/A engines this benefit would be smaller.

bmwman91 · « **Reply #23 on:** June 09, 2007, 11:31:48 AM »

I am sure you did. A 944T flows a LOT more air, and a lot of cars that flowed a lot that used an AFM ended up getting restricted there. There is a limit to the size of the flapper door just out of consideration for inertia/momentum effects on the response speed. This, and possibly possible emissions and power-related taxes could limit air flow, or create a need to limit it.

Now the M42 is a small NA motor. It does not really flow that much aur. The AFM on it is just fine. I was just saying that on the M42 you will get no gains. The M20 would see some gains if a MAF was put on in place of its (undersized) AFM.

The M42 DOES get better throttle response with a MAF, better idle stability and better off-idle response. I have been driving on my MAF conversion for ~9000 miles now and have no reason to stop! Well, heck the stock AFM was on its way out anyway!

ose30 · « **Reply #24 on:** June 09, 2007, 02:28:12 PM »

944 T has a 2,5 liter engine, so volumes are larger as you said. I know one 944 NA project going on which has AFM replaced with SMT6 and Bosch MAF sensor. I'll report here what the results are when owner of that car have it dynoed.

nomad · « **Reply #25 on:** June 09, 2007, 02:33:13 PM »

It does seem that this mod would be best used in conjunction with a chip that is set up for it.
Without a chip I can see the computer not metering it properly. Then again, with the stock MAF it should be metering all the air that is coming in correctly. At part throttle it may not be an issue but I wonder about WOT in the closed loop stock mode going lean.

Boyracer · « **Reply #26 on:** June 09, 2007, 04:22:13 PM »

I just checked what Metric Mechanics use for throttle body on their engines (upto 210 hp in NA configuration)...

Stock TB! Not even a single mention about enlarging it anywhere :eek:

I think that indicates it is large enough for mild tuning we usually deal with in our street engines. Same for intake runners...

The real restriction is the cylinder head and valves. But they are quite big mod.

tjts1 · « **Reply #27 on:** June 09, 2007, 08:48:04 PM »

Quote from: Boyracer;27469

Stock TB! Not even a single mention about enlarging it anywhere :eek:

They even have the stock TB heater in place. Makes you think

Alpine003 · « **Reply #28 on:** June 10, 2007, 12:12:51 AM »

Quote from: bmwman91;27444

Not true. I did a MAF conversion on mine and saw NO power gains. From looking at datalogs of flow data, no more air flows with a MAF.

I never said the barn door was restrictive with a stock tb but there will be a point when you increase the tb size where the barn door will act as a bottle neck. Your research just dealt with the stock tb which I'm sure the BMW engineers designed the barn yard flow accordingly.

redhead · « **Reply #29 on:** June 10, 2007, 02:58:28 AM »

I was thinking about duplicating the MM pulse manifold and interested how your prototype is going to turn out. Please keep us in the know!