ITBs, hot cam and long tubes on a b25: worth it?

[thatphysicsguy]

Hey all,
I'm looking into building a spiced up m20 this summer, and I'm considering the above mods.

Currently I'm all stock and looking to keep the 2.5 displacement. I bet there are threads out there, but when I search, the builds center around ppl making their own ITBs rather than talking about the overall build.

I know the m20 is already pretty well optimized out of the box, but would these mods add enough spice to the engine to justify the cost? (a matter of opinion of course, but I'd like to hear them)

So where can I find more info about building a sweet, non-stroked N/A m20?

[efficient]

you'd probably spend a lot of money for a small gain. the car might sound beast though.
don't forget that you'll need megasquirt or some kind of ecu tuning

[TheTacoMan]

Problem with ITBs is its a trade of power, changes the peak hp yes but at the loss of bottom end in combination with a cam. Really depends on what you want out of the car, for the price of itbs and the small gains, its really close to turbo $$ territory.

[whitebulat22]

There was this thread on that: http://www.e30tech.com/forum/showthr...119127&page=12

There and in threads in this M20 section it has been shown that 45 mm throttles like the ones Dbilas offers are so improperly sized they barely even help high RPMs while 40 mm or so like the ones you can get at RHD Engineering work extremely well everywhere. The record I've seen on 93 octane M20 is the 293 whp one they built, so allow a lot of room below that to compensate for our 91, street application, probably less spending, and stock displacement. With that much flow from the mods you're talking on the high rod-ratio stock assembly revs may be dangerously high so maybe keep the cam at something non ridiculous so you don't have to explore uncharted RPM territory.

If you're staying near stock compression that would be another reason to stay non-extreme with the cam. If you want to spend the money on the parts people have actually seen 30 whp gains on stock M20B25s with the throttles and over a wide range so you would get a thorough improvement in the end and will beat the ludicrous "$100 per 1 NA HP" rule handily.

Breathing on an M30 will be a lot less work and cash for similar gains. Factoring in the M20b25 sale it might be basically free. All up to you if you'd rather a unique boundary pushing build or something out of nothing.

[digger]

OP you are looking at about $2500 minimum outlay if you install everything yourself and thats pushing it, how much power are you looking for? you probably wont beat the numbers below (same as the e30tech link) which had a ported head. id say 170whp ish depends how fresh the bottom end is

http://www.r3vlimited.com/board/showthread.php?t=330450&page=5

[sayed ali]

N/A m20 would cost alot and will result in small power gain,

ITBs, cam, headers, ems, some fuel upgrades, etc..

so add a turbo too & you'll be a big winner :)

[brody]

You can keep the stock manifold and cam, use our PSIK, and gain 25 to 30 hp for $525. You get a massive improvement in engine response and performance with no hassle of having to use a standalone for an ITB setup. The induction sound too by the way is quite something.

The PSIK is by far the most bolt on power you can do to an M20B25.

https://www.millerperformancecars.com/store/maf-conversions/m20-cold-air-intake-maf-kit-psik-detail

[digger]

You can keep the stock manifold and cam, use our PSIK, and gain 25 to 30 hp for $525. You get a massive improvement in engine response and performance with no hassle of having to use a standalone for an ITB setup. The induction sound too by the way is quite something.

The PSIK is by far the most bolt on power you can do to an M20B25.

https://www.millerperformancecars.co...it-psik-detail

the lack of independent data doesnt help the PSIK which i do think is good value for someone who wants a little more fasts, a mostly plug and play solution and has no grand plans for the m20 making alot of hp.

[thatphysicsguy]

Thanks for the input, guys!

I'm mainly looking for great sound and really sharp throttle response. If I wanted power, I would go turbo or swap etc.

Instead my goal is something that compliments the original spirit of the car. I want to keep the E30 as a sort of improved time capsule that sounds great and drives similar to the original.

It sounds like I should just get a good sounding exhaust and save the rest of my money for a separate balls-to-the wall build.

[brody]

the lack of independent data doesnt help the PSIK which i do think is good value for someone who wants a little more fasts, a mostly plug and play solution and has no grand plans for the m20 making alot of hp.

The "independent data" card is getting old. There are plenty of shops, race cars and people who have provided data and highly, highly recommend the PSIK over the last few years. We aren't new to the game and our reputation is pretty strong.

Just a month ago or so a customer shot me some 1/4 mile data from his AUTO 325i VERT which picked up over 1 full second and a 4 MPH when compared to the same car without the PSIK.

https://www.millerperformancecars.com/files/Dynos/PSIK%20times.png

[aintnothang]

But they look so good.

[cdeason]

mods

For my money, I would use MAXX Alpha-N, I have it on my E30 M3 and it was the best bang for the buck by far. I plan on using it on my M20 2.8L build.

[M-technik-3]

dBilas makes or made a system

http://www.dbilas-shop.com/Products/Throttle-body-kit/Street/BMW/Throttle-body-kit-for-BMW-320i-323i-E30-520i-523i-E34-2-0-2-7-12V-M20::8595.html?XTCsid=29pp9aq6i3uefvn1qrpc0f2kj6

[digger]

dBilas makes or made a system



http://www.dbilas-shop.com/Products/...fvn1qrpc0f2kj6

and it sucks

[aintnothang]

Look at the setup that CA tuned used on that blue car.