ForcedFirebird's m20 dyno thread.

[Stephen]

Updated post #2





Sorry, missed your post until editing post 2. If you notice, they are kinda in an order from stock-ish to built, so bear with me. I have not had a local 3.x built m20 to put on the dyno yet. Have a budget stroker using the eta crank/rods, -2mm block, B&B to .1gm, stock-ish head with just my flow tested valve job, and 272 cam that will be coming back for the tune once it's broken in a bit, but logistics has been keeping it delayed as he is over a half day drive from the shop. I also lost in the neighborhood of 20 cars when the dyno pc tower crashed - the same reason I now cloud them shortly after. :/

Interested to see what that puts down!

[ForcedFirebird]

Same car as post #3 and #23, but added a lightened/balanced/blueprinted 2.8 rotating assembly (has heavy 130mm m20 rods at 550gms), 2mm shaved block, 9.5:1 compression. We played with the runner lengths on the ITB's and got a ma peak of 217/202, but it was so peaky. This was the settled tune and runner length (most area under the curve).



Overlay from when we met the car to current status. Trying to talk him into a larger cam. Even though the compression is 9.5:1, the RHD ITB's are great at cylinder filling and believe a larger cam would help this one out...

[ForcedFirebird]

What causes the waviness in the curve? Is it from the restrictive exhaust?

More than likely. I played with the tune and couldn't smooth it out. Have a feeling there was some kind of pressure oscillation going on.

EDIT: It also could have been in part due to the manual boost controller. 6psi spring, it would only make 13 in a spike, then fall to 12 with the controller wide open.

[ForcedFirebird]

m20b25 with flat eta style pistons, 10psi stable, authentic Tubonetics Super 60, Bimmerheads head with dual pattern turbo cam, ebay tubo manifold, customer built.

We added Megasquirt, fixed up some piping an dyno tuned it.

[earthwormjim]

What causes the waviness in the curve? Is it from the restrictive exhaust?

[ForcedFirebird]

272 your favorite cam?

Kidding aside. I base the cam on the compression. When you have less than 10:1, anything larger than a 272 puts the power band higher than the m20 head will make power.



Here's one of the lost dyno files, but realized we focused the camera at the dyno, woot


Stock 1988 seta engine with fresh rings, bearings and rebuilt head. Stock cam, eBay clone of a to4e/super60, spiked to 13psi, then held 12 stable. 524 TD manifold with a long adapter in between it and turbo to use a 38mm external gate. 3" DP, stock-ish exhaust with cat (yes, choking it), but he moved to Cali and wanted to be able to convert back to stock if needed.





Not sure why the youtube embed isn't working anymore on vbulliten, but here's the vid...

https://www.youtube.com/watch?v=LPxpliUiNwI

[ForcedFirebird]

272 your favorite cam?

Im just a pawn in this game, my man.

[LowR3V'in]

272 your favorite cam?

[ForcedFirebird]

Updated post #2

Do us dirty and post up a 3.xL if you got any :p

Sorry, missed your post until editing post 2. If you notice, they are kinda in an order from stock-ish to built, so bear with me. I have not had a local 3.x built m20 to put on the dyno yet. Have a budget stroker using the eta crank/rods, -2mm block, B&B to .1gm, stock-ish head with just my flow tested valve job, and 272 cam that will be coming back for the tune once it's broken in a bit, but logistics has been keeping it delayed as he is over a half day drive from the shop. I also lost in the neighborhood of 20 cars when the dyno pc tower crashed - the same reason I now cloud them shortly after. :/

[ForcedFirebird]

Same car in post #3 with our head, 272 cam and RHD ITB.Check out the TQ at 2500 rpm, it's more than peak in the base lol.

[ForcedFirebird]

Ah, sorry... my bad. It seems that we have so many correction factors, hp standards, measurement styles (whp or transmission losses corrected) that it makes me crazy. Thanks for sharing these!

No harm, no foul. HA

With low power engines, it's not as much of a big deal. When changing correction factors on a ~150whp car only changes the numbers a few HP. Naturally when you get to higher HP, the differences are large since it's a percentage based formula.

[hasa]

Ironic you asked. If you look at the screen shots, they are in EEC.

Ah, sorry... my bad. It seems that we have so many correction factors, hp standards, measurement styles (whp or transmission losses corrected) that it makes me crazy. Thanks for sharing these!

[ForcedFirebird]

Been a little backed up lately. :/

[LowR3V'in]

he's shy now

[2mAn]

Give use your most bad ass m20 dyno and what u did to it.

Or just give us more!!