ForcedFirebird's m20 dyno thread.

[ForcedFirebird]

Right on Bobbie - strong motors. Been a bit since we dyno'd an m20. Built a few 24vs and am going next week for a 13b rotary MS/ITB conversion.

I have a hard time with the 12:1 and stock - or 272 cam for that matter. Might want to see about that information. With a stock cam and 9.4:1 we are seeing 200psi cranking compression, I would expect detonation in the mid range with pump fuel, and 225+ cranking compression with 12:1 and stock cam (another member here was having detonation issues with 11:1 and 272 cam).

It appears car #2 could use some fuel trimming, for sure. Car #1 also seems like a little less fuel at 5700 would help the peak.

We saw just the opposite. Our MS car did about 6 more whp over the stock ECU car, but was with headers, extruded intake and stock cam added.

Send me the files to John@m20guru.com, maybe I can overlay them. The scaling is different between the runs, might just have to scale everything.

[digger]

thanks for posting

[AWDBOB]

Figured I'd add to this thread- two 3L M20 cars built by Zionsville Autosport went on a local Dynojet today.

Both M20b30s were built using M54b30 internals, pistons shaved down 2mm and then had .0017 of ceramic coating added to the domes. Using a thicker MLS (not totally sure of exact size), compression is supposedly around 12:1. These aren't my claims, just the info I got from Dwight.

Car one was stock ecu, car two was Megasquirt. Stock ECU car had a 272 cam and a BBTB, but made less power than the car with Megasquirt.

Dwight and I had a bet on what the Megasquirt car would make, I guessed 185/210.

Anyway, onto the results. Also, to note, I tried to do an overlay in WinPep but couldn't get it to read right. I have the dyno files that I can send someone if they cared to do an overlay of cars 1&2.


Car #1:

Runs 1&2 are with stock chip in the stock ECU, runs 3&4 are with an SSSquid chip setup for this configuration of parts. You can see the curve smoothes out and AFRs also get much safer with the squid chip where the stock ECU was going lean.

Bolt ons:

-IE Billet 272 Cam
-BBTB

MILLS by Bobbie Morrone, on Flickr





Car #2:

This car has a PNP Megasquirt setup with a Miller MAF somehow configured in there. I don't know the details of the t00n, but the bottom end is the exact same as car #1.

This car has a stock cam, and otherwise doesn't have any mods outside of the standalone, but made much stronger numbers. The tune is crazy rich up until 5K, and falls off like crazy after 6K.

LILE by Bobbie Morrone, on Flickr



Edit: Adding a photo of car #1 because it's a beautiful, extremely low mile Japanese MT2 car.

Untitled by Bobbie Morrone, on Flickr

[ForcedFirebird]

have you seen any power from retarding the cam seeing as allot of people resurfaced/shaved heads but with no adjustable gear.

Yes. Apparently the Schrick likes to be ~4° behind. In a racing series you may be docked points for using an adjustable gear, though....

[RobE30]

This thread is great. Thanks to everyone who's contributed. After reading through it, I'm amazed that my engine (284/272) on a stock b25 has held up d/t my severe lack of knowledge with tolerances/clearances. Round 2 is going to be much better.

How many miles should a Schrick 284/272 cam last? I think I'm around 40k, regular oil changes Castrol GTX 20/50

[dvallis]

Hey Varg, that's a good way to look at it. We've got a nice study of HP for M20 turbo stroker builds.

[varg]

Thanks for that, dvallis. It is very rare that someone posts a dyno printout that good. Usually it's one or two runs just to brag about the peak hp number when the comparison is the real value of a dyno in the first place. I had a little fun with your numbers since I don't get to see this kind of comparison with turbo cars too often. Of course it's not gospel, just for comparison, and forcing linearity is only way to easily display what kind of power increase your build is seeing per added psi of boost (the slope of the line).

[dvallis]

It's really well behaved, drivable and fun. I'm getting 5-10 psi boost at partial throttle, so maybe 200-250 HP. At WOT 19 psi the boost comes on like Mike Tyson punching you in the face. Make sure you're pointed in a straight line, hold on and try not to scream like a little girl. :-)

[gnmzl]

That's a curve I'd love to see in any of my cars. How does it drive, did you get a chance to test it?

[dvallis]

Das Beast 2.8L turbo stroker M20

See Build Thread page 1 for specs

BLACK : 6 psi
RED : 10 psi
BLUE: 16 psi
GREEN: 19 psi

[ForcedFirebird]

I'm not sweating it Keith, it's relevant. What did you do for the CPS?

Right on dvallis.

[dvallis]

'Bird this is a great thread. Will be sure to post my dyno run here.

[whodwho]

yes there is only one but i'm against incorporating additional idlers, tensioners into the Vee belt system for the additional cost, points of failure and maintenance.

You threw me on the 'timing belt'. You could run without the tensioner and idler and just use the manual adjusters and would be 100% stock BMW non maintenance parts. it allows to run a newer damper and one that's tuned (if there is any real difference) for the 84mm crank that I am running. I also have a ATI damper for my S54 that I am seeing what I can do for a hub.

it would make more sense on an M30 which needs the extra space

Or a supercharger setup 8^)

(ignore the alternator holding up the SC, that was just to hold it while checking the SC > plenum > throttles alignment)

Only options ATM are using a 24v damper, which is larger in diameter and has the OlT mark at 2 o'clock vs 10 o'clock (easy fix), will require custom CPS bracket and either change to vee belt damper, or serpentine alternator other oprtion is totally a custom /adapted unit.

Sorry for derailing your thread I though it was relevant to your post, I will make a new thread

[digger]

yes there is only one but i'm against incorporating additional idlers, tensioners into the Vee belt system for the additional cost, points of failure and maintenance.

it would make more sense on an M30 which needs the extra space

[whodwho]

one tensioner on the timing belt is more than enough....

I don't understand your statement?? There is only one