ForcedFirebird's m20 dyno thread.

[redlightpete]

Did these both have stock cams and non-adjustable cam gears?

[ForcedFirebird]

Wow those numbers are fantastic for a 2.7 stroker. That's promising data for anyone thinking about going that route.

These are NOT 2.7 short blocks with a 885 heads. They are 81mm cranks, 130mm rods, stock b25 pistons and machine the block deck to get compression height back. We took .080" off these blocks, but beware of squish. Both engines got shaved heads, one was too close at .035" piston to head clearance. To be safe without measuring, I would suggest taking .070-.075" if you want to use an off the shelf head gasket.

[Reichart12]

Wow those numbers are fantastic for a 2.7 stroker. That's promising data for anyone thinking about going that route.

[ForcedFirebird]

Did two "budget stroker" 2.7's today on the dynojet. Will post results and anecdotes later, but 2.7 crank/rods with b25 pistons and milled deck is super viable, even with the reduction in cam timing.

2 examples today. One made at the wheels: 180hp/179tq and the other did 168hp/172tq

Stock used blocks/pistons, fresh rings/bearings, a bbtb, headers, and even aftermarket ECU was involved. Lol

[ForcedFirebird]

John clear your inbox :)

Email is valid in signature. Barely sit at PC anymore, even cell phone sits in office. This is racing season in FL....

[jeffnhiscars]

John clear your inbox :)

[ForcedFirebird]

Interested to see what that puts down!

Building another one now that will surely go to the dyno as it's getting installed in the race car and will need plots for HP/WT ratio for classing.

updates!?

None lately. Have an s50 rebuild in the works, and it's racing season so we will be going to the rollers soon.

[2mAn]

updates!?

[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.