Almost stock m20 dyno

[darvo]

Today I went ahead and dynoes my almost stock 91 325i coupe, I bought the car a month ago, the had a poor 2 1/4 exhaust with a resonator from the stock DP on to the stock muffler. I had a Megasquirt 1 with a V3.0 board laying around @ my folks from another E30(eta) I now have for parts.

So i was tired of the car being so slow, so I went to a muffler shop replaced the exhaust with a single 2.5 inch without cats or resonators, from the stock DP to the stock muffler,called my tuner a made a "street tune" with the car because there was no dyno available.
Today I went to the dyno and made a runner with the stock motronic and another with the MS1. The car still has AFM and airbox.

In another 2 weeks I will take it again to fine tune it with the GM Iat sensor with an intake to delete the stock AFM and airbox and install an E36 TPS for a more linear tune.

Numbers:

[darvo]

This was on stock 14lbs inyectors and cheap 87oct fuel.

[dougie30]

i thought the stock i engine had close to 170 hp?

[acolella76]

i thought the stock i engine had close to 170 hp?

at the flywheel. some of that power is used to turn accessories and gears and gets 'lost' in the drivetrain.

[SpecM]

i thought the stock i engine had close to 170 hp?

at the flywheel. some of that power is used to turn accessories and gears and gets 'lost' in the drivetrain.

this ^

also, this is when the engine was NEW. the rings/cam/valves have some wear/age on them now

[jlevie]

The wiggles in the traces above 3500rpm suggest not enough ignition advance. It also looks like you need to pull back a little on fuel around 4500 & 5500rpm. Otherwise the data (& tune) looks pretty decent.

The numbers look pretty decent, but below what a stock M20B25 in pretty good condition is capable of and well below what a race built M20B25 can do. I like to see around 152/150 for a good ordinary engine and about 160/158 (or a bit better) from a race built engine. And that is using the stock engine parts & management system. As data points, my Spec E30 has a race built engine and made 162/159 on a 100F day. The numbers would have been slightly higher on a cooler day. My restoration project (an 87 325is) has an engine that I rebuilt, but didn't get the full race prep, and it made 153/151 on an 85F day. The differences between those engines is that race engine has 50 over pistons, a head decked to the max, coated bearings, has been balanced, and has a straight through exhaust (no resonators or cats). Other than the decking both heads got the same treatment. New exhaust valves, matched springs, polished rockers, blueprinted cam, new guides, three angle valve job, and the valves were lapped in. The head is where you make power, so careful attention there pays off. Both cars have a stock DME, but some external tuning tweaks were done. On the race car it was done to the limit of the rules, but I didn't go that far on the street car as drivability would suffer.

One has to be careful when looking at dyno numbers. The conditions, skill of the operator, make of dyno, and condition & type of tires all affect the results. And DynoJet is a bit optimistic as compared to other makes. Looking at absolute numbers from different cars done at various times and places (or comparing to book valves) can be misleading.

[darvo]

The wiggles in the traces above 3500rpm suggest not enough ignition advance. It also looks like you need to pull back a little on fuel around 4500 & 5500rpm. Otherwise the data (& tune) looks pretty decent.

The numbers look pretty decent, but below what a stock M20B25 in pretty good condition is capable of and well below what a race built M20B25 can do. I like to see around 152/150 for a good ordinary engine and about 160/158 (or a bit better) from a race built engine. And that is using the stock engine parts & management system. As data points, my Spec E30 has a race built engine and made 162/159 on a 100F day. The numbers would have been slightly higher on a cooler day. My restoration project (an 87 325is) has an engine that I rebuilt, but didn't get the full race prep, and it made 153/151 on an 85F day. The differences between those engines is that race engine has 50 over pistons, a head decked to the max, coated bearings, has been balanced, and has a straight through exhaust (no resonators or cats). Other than the decking both heads got the same treatment. New exhaust valves, matched springs, polished rockers, blueprinted cam, new guides, three angle valve job, and the valves were lapped in. The head is where you make power, so careful attention there pays off. Both cars have a stock DME, but some external tuning tweaks were done. On the race car it was done to the limit of the rules, but I didn't go that far on the street car as drivability would suffer.

One has to be careful when looking at dyno numbers. The conditions, skill of the operator, make of dyno, and condition & type of tires all affect the results. And DynoJet is a bit optimistic as compared to other makes. Looking at absolute numbers from different cars done at various times and places (or comparing to book valves) can be misleading.

this was just a street tune(guetto tune) that my tuner did because I couldnt wait till he came back from a drag event in the states, there was no timing involved in this one, in about 2 weeks more the car will be fine tuned, better AF ratios @ the same dynojet. So there will be better numbers next time(I hope) ;) . Also the odometer stopped @ 149,497 almost 2 years ago ( I asked previous owner when the car was bought). So its far from a blueprinted and healthly engine.

And believe me when I got it, it was slow as .....

I just want to know how the car will evolve since I bought it.

I'll send you a PM to talk more about the head work.

Thanks for posting!

[digger]

Nice results, i guess the thing that always makes me hesitate with a custom tune to get things running correctly is why is it not running correctly in the first place? did you check all the major items and make sure the maintenance is up to scratch and running as absolute best as it could with the current map?
The last thing you want to do is tune for bad injectors (or something else) and then when they get replaced down the line the tune is out again.

[darvo]

Everything is good as of now..... Just talked to the tuner he arrives on sunday so maybe this week or the other I'll have a better tune

[dougie30]

this ^

also, this is when the engine was NEW. the rings/cam/valves have some wear/age on them now

ahh i see, and nice dyno runs man i have to do this when i get my engine back in

[nando]

nice job, you'll see more with some better tuning.

also, an E36 TPS will basically have zero affect on your tune or power curve. It's really only used for things like activating idle, decel fuel cut, and AE/transient fueling. Mostly driveability.

[darvo]

nice job, you'll see more with some better tuning.

also, an E36 TPS will basically have zero affect on your tune or power curve. It's really only used for things like activating idle, decel fuel cut, and AE/transient fueling. Mostly driveability.

Thanks! Driveability is a plus, this is my daily right now. :D