From knowing nothing to having a Thunderbird supercharger on an m20b27i

[Ether-D]

Noooooo nit what i wanted to read!!!bring it over this weekend and we can check it out.

I know, right? Yeah, maybe Sunday...

[The Dark Side of Will]

It only makes the noise when still in vacuum. But I'll try that tomorrow anyway if only to check the s/c coupler. Thanks bro.

You said light throttle...
Could be that there's not much torque on the coupler at light throttle, as the engine's pulling air about the same rate the SC is delivering it (and the bypass is open, right?). When you put your foot down, the bypass closes, the throttle opens and the coupler takes a lot of torque, preventing play in it from making noise.

[Ether-D]

Yeah, I like that. Fingers crossed...

[MaxBell]

I was trying to look through the thread, I don't see if you have any updated engine management.

Are you just running the stock ECU?

[Ether-D]

No, I'm running ms2.

Regardless, I just removed the blower belt and the sound is still there. Internal engine something. I've had a sticking valve before, it was much louder than this noise. I've wasted a rod bearing before, much louder than this noise. It sounds to me like rod bearing light. Maybe just early bearing failure (or rod small end like LJ said). I'm gonna pull my other short block to drop in, and start collecting the stroker parts.

[Ether-D]

P.S.
Not being a smartass (maybe a little…), but you can search individual threads with the "search this thread" button.

[Ether-D]

Ok, so I'm reading about strokers to replace my rattly bottom with (while i'm in there…). There's the 2.7 and the 2.8 budget strokers. I'm getting the feeling that the 2.7i (b27 bottom b25 top) is the way to go (for me) because of lower compression for forced induction. Is this the correct idea? What would I gain from the 2.8 besides higher compression and .1L more displacement? And would the higher compression actually hurt me? I'm also thinking a m20b27 bottom would be easy to source and likely very cheap. I'll probably do a full rebuild on whatever bottom I go with so as to start with a "new" bottom, wear-wise.

2.7:
no machining
easy to source
cheaper
lower compression
lower revolutions per lower r3v limit so lower wear

2.8:
.1L more displacement

Seems pretty cut and dried, unless any of yous can tell me why I should go 2.8 instead.

[The Dark Side of Will]

3.0 stroker ;)

[Ether-D]

Sooo much more money… Am I on the right track here though?

[The Dark Side of Will]

You can get a whole M54B30 for $500 and probably sell the cylinder head for $250 when you're done.

Nando's done a M20B30... ask him what it took.
Remember what we said soooo many pages ago about the blower working better with bigger engines...

[Ether-D]

I know bigger will be better for the m90, but I think I want to also have lower compression. What's the theory about lower compression and FI? Is it about lessening the likelihood of pre-ignition and/or detonation? If so, is that the only thing it does for you?

[agent]

You can get a whole M54B30 for $500

Where?

[The Dark Side of Will]

Where?

https://www.car-parts.com

I know bigger will be better for the m90, but I think I want to also have lower compression. What's the theory about lower compression and FI? Is it about lessening the likelihood of pre-ignition and/or detonation? If so, is that the only thing it does for you?

Lower compression raises the threshold (in terms of temperature and boost pressre) for detonation at a given fuel octane.

Preignition and detonation are very different things.

[agent]

Where?

www.car-parts.com

Maybe for only the short block. Here is the first page of M54B30s on car-part.com sorted by distance:

[TheTacoMan]

2.7:
no machining
easy to source
cheaper
lower compression
lower revolutions per lower r3v limit so lower wear

Wut? I have my 2.7 spinning up to 7100 right now, 2.7i doesnt have a limiting factor to revving, same as a 2.5i as far as Im concerned.
The lower compression means that it will be less prone to detonate with bad gas generally speaking, this doesnt mean you can run lesser gas than 91. The 2.7i really isnt far off of a 2.5i when they are both boosted, sure it will spool the turbo quicker but the lesser compression also hinders spool time.
I would try to find a supereta if you go 2.7i as they have better compression than just the e.