ForcedFirebird's m20 dyno thread.

[digger]

Get one sent to your little island. It will be worth it though getting the original crank you had planned is probably better as the bottom end and midrange torque will be a lot better

[darvo]

Yup, the 84 would be perfect my main problem is availability where I live. Live on a little island

[digger]

Why not use 84mm stroke as that works almost spot on or get another 89.6 crank they aren't expensive in the grand scheme of the overall build process

[darvo]

Honestly I have not done much with the adjustable gears on the dyno.


Here's the graphs from Sat.



81mm crank, 130mm rods, b25 pistons, .080" (2.03mm) off the deck, stock cam (and cam gear), in house rebuilt head, .035 quench, bored throttle body, extrude manifold, eBay headers, single 2.5" exhaust through 2 mufflers. MS1 with a smooth elbow pipe, cone filter.


[ATTACH]125591[/ATTACH]


81mm crank, 130mm rods, b25 pistons, .080" (2.03mm) off the deck, IE 272 cam (stock cam gear), in house rebuilt head, .050" quench, stock intake/TB, stock exhaust manifolds, single 2.5" exhaust with a single resonator. Stock ECU re-mapped at the dyno.


I believe this car "should" have made more power, was actually a little disappointed. Later after watching a video sent by a friend, I can hear a lot of diff noise that was impossible for me to hear in the car while tuning (one car bay with a dyno in it). Doubt we will bring it back to the dyno, just rebuild the diff and send it racing.



[ATTACH]125592[/ATTACH]

Nice Dyno #'s! I recently purchased a set of 12:1 85mm Vac 885 head pistons for a 89.6 and 135mm stroker build but the m54 block I had in mind was thrown away before I got to it.

So I found a set of 138mm rods that I'll use with a 81mm eta crank to build my 2.7i. I'mm just have to deck the block 1mm and put a thicker 0.100" gasket to lower compression to 11.5:1.

I'll be using my stock 885 head and 284/272 schrick which made my stock b25 anemic down low.

Looking forward to end results.

[darvo]

Oh yea thats right.

I was thinking about my SuperETA block...

Im really curious what mine will make with the package I am expecting in a week ;)

What will your setup be?

[2mAn]

The added stroke is what bumps the compression - swept volume. The 2mm off the deck is because the crank is 6mm more (3mm up, 3mm down strokes), but the rods are 5mm shorter than b25. Taking the 2mm puts the pistons back up close to the head. If you didn't shave them, you would have an extremely large quench/squish (distance between the head and pistons at TDC).

Oh yea thats right.

I was thinking about my SuperETA block...

Im really curious what mine will make with the package I am expecting in a week ;)

[ForcedFirebird]

Would it matter as much on an FI engine?

That's a whole 'nother conversation. When you pressurize a system, you are no longer relying on the atmosphere to "allow" the air charge to enter an engine, you are "forcing" it in.



I actually prefer to make an engine as strong as I can BEFORE adding above atmo. The old saying "lower the compression, add more boost" is moot in modern days - when generally, if you have a strong engine and add boost, the strong engine will always out perform a low compression over all - just keep in mind when you have a lot of added static compression and add boost, your tuning window gets extremely small - low compression/high boost engines are very forgiving on timing and fuel delivery, and fuel type becomes critical on high comp.

I am not afraid to boost 10:1 engines. The low compression gig is a fallacy IMO.


I like to say N/A all the way! Anyone can throw a big turbo on a car, not many people can pull big numbers from an N/A engine.

[digger]

50% more flow from making it a poofteenth bigger? yeah righto....they are also doing it wrong as you need a piece at the end to stop the edges of the exit being rounded over and screwing up the matching of the interface to the head

i had a manifold treated with a similar process (but not EH) the flow numbers improved and so did the balance but it made noticeably less power by 9whp...i got a spare one treated so it wasn't the same manifold. if it made the same power then i could say maybe th operator didn't pump enough shit down its throat, but to go backward maybe the polish isn't so good? the AFR were identical within 0.2AFR the entire run with no tune changes so probably moving the same amount of air but not making power from it so combustion efficiency and BSFC down the toilet. after that i got the MM pulse tune manifold and did a cam swap

[LowR3V'in]

on that extrude vid u linked
i don't really know what those numbers really mean but just notice
the very even distribution of the runners.
Seems like a good thing but based on the number differences before/after
is it worth the money vs power you are seeing? Would it matter as much on an FI engine?

[ForcedFirebird]

How much of a difference do you think it is with and without that 2mm off the deck? Im guessing that bumps the CR from ~8.5:1 to ~9.5:1

The added stroke is what bumps the compression - swept volume. The 2mm off the deck is because the crank is 6mm more (3mm up, 3mm down strokes), but the rods are 5mm shorter than b25. Taking the 2mm puts the pistons back up close to the head. If you didn't shave them, you would have an extremely large quench/squish (distance between the head and pistons at TDC).

[2mAn]

How much of a difference do you think it is with and without that 2mm off the deck? Im guessing that bumps the CR from ~8.5:1 to ~9.5:1

[ForcedFirebird]

How is an "extrude hone" done in a curving intake runner like that? I'm trying to picture the hardware that does this. Is it just smoothing, or removing metal to enlarge the diameter?

Thanks -

https://www.youtube.com/watch?v=2QBc59YZYxA

[LateFan]

How is an "extrude hone" done in a curving intake runner like that? I'm trying to picture the hardware that does this. Is it just smoothing, or removing metal to enlarge the diameter?

Thanks -

[ForcedFirebird]

my guess is the differences are mostly breathing mods

looks like that cam isn't doing shit

I just pushed the car into a spot to pull the diff, and something is dragging pretty hard. It's very easy to push backwards, but going forward is 2x the effort.



As far as the 2 engines and the cam, one added lift/duration for more flow with nothing upstream, and the stock cam car increased flow before/after combustion. I have dyno tested headers similar to these and they are worth 5-8whp/tq - but we are missing closer to 10.

[LowR3V'in]

looks like that cam isn't doing shit