NA is best - 3.1L M20 w/ ITB's

[ForcedFirebird]

Love everything about your build! Well done.

[The_Lope7]

Damn its crazy how much that small design side changes the look of the car. Engine bay and all looks fantastic!

[Raxe]

200km so far this year and the car drives great, can barely even tell it's heavily modified aside from the sound and power. I'm just planning some small cosmetic changes and touch-ups this year, I do have all of the parts now to hook up the vacuum for the FPR and install a catch can but honestly with it running how it is I'm content just driving it around and enjoying it for the time being. :)

[saucers]

updates!

[Raxe]

Did you ever finish up the tune and dyno the car? Curious what it made!

Did you run out of injectors? I'm at ~85% IDC on 24# injectors, and my car has the stock intake manifold, 2.5L, with a 284/272 cam and 9.7:1 pistons. It made ~200-210rwhp (depending on the smoothing applied). I figure I will need to go up to 28# injectors when I install ITB's.

The car is back in storage for winter and I haven't seen or thought about it for a few months now. :(

My tune is streetable and I've driven around 800km on it so far but haven't had it professionally honed or dyno'd yet. I found a place that is comfortable with it but they're a few hours away and I'm not sure I'm ready to take it out on the highway, hoping I can convince a buddy to help me trailer it down this summer.

If I recall the highest duty cycle I've seen is 80%, but I also don't think I've actually revved it over ~6000rpm.

Towards the end of summer I was running into issues with it misfiring and leaning out after a hard pull, I'm thinking the throttles may be unsynchronized slightly or something in the linkage might need adjusting. It would run great from start all the way through warm up and driving around the AFR would be very stable, but after flooring it once or twice the AFR would start creeping up and it'll afterfire/pop at low load cruise until it fully cools down.

Sadly as I'm sitting here typing this out I'm realizing how much I've forgotten already, it'll be a rocky start this spring as I try to remember where I left off last year haha.

[Digitalwave]

Did you ever finish up the tune and dyno the car? Curious what it made!

Did you run out of injectors? I'm at ~85% IDC on 24# injectors, and my car has the stock intake manifold, 2.5L, with a 284/272 cam and 9.7:1 pistons. It made ~200-210rwhp (depending on the smoothing applied). I figure I will need to go up to 28# injectors when I install ITB's.

[jeenyus]

great build. been fun reading through this.

[318aye]

Very interested in your results!

[lindskrot]

Wonderful car

Hi.

I´m new on this forum and I have just gone through your thread with great interest! You have a beautiful car!

Myself i have a dolphin grey 1987 325iS with a M20B30 with RHD ITB's and running on E85.


I am currently adding the extra vacuum runners and vacuum plenum to my car aswell. Planning to use idle control valve and vacuum for FPR.
But i am also thinking about using a hybrid map using TPS and MAP-sensor to get better driveability and idle.

Would be great to see any update in this thread!

Added a pic of my car, but i only had one of my boat aswell. BTW i'm from Sweden and my car is probably the only E30 running RHD ITB in the whole country.

Best regards!

[Schlander]

Could you post your IG and VE table? :)

[Raxe]

noisy? the check valve makes no noise, or is it something inside the booster making whooshing noise? something unavoidable is that a 288 with ITB is going to have lower vacuum than stock

It's making a "tink tink tink" noise under braking, only at a stop or coming to a stop... confirmed it today with a stethoscope, it's loud enough to hear inside the car. Pretty strange, and it goes away immediately under load. I might order another to eliminate the possibility of a randomly faulty valve as they're cheap enough. Braking force is adequate, no issues with the assist other than the unusual noise. I suppose it could be from the booster itself, though it seems quiet with the stethoscope.

Very nice, what headers are those?

Thanks, they're IE shorty headers.

[parkerbink]

Very nice, what headers are those?

[digger]

noisy? the check valve makes no noise, or is it something inside the booster making whooshing noise? something unavoidable is that a 288 with ITB is going to have lower vacuum than stock

[Raxe]

Just hit 100km on it today and feeling a lot better about it now. Most of the quirks have been ironed out and it's idling and driving well. Cold starts are still tough, I'm inching towards a good WUE formula but after the initial start it's fine for the day. Idle is still on the rich side as well, but I'm hoping I can improve that by getting the injector dead time figured out.

Only new problem I've had come up is the (new) brake booster check valve is getting increasingly noisy, I'm wondering it if too has to do with the pulsing vacuum but I'm expecting it's on its way out already.

Pic from today after a nice drive:

[digger]

sounds like it is coming along nicely, digging the matte black airbox to it looks more in theme