From knowing nothing to having a Thunderbird supercharger on an m20b27i

[TheTacoMan]

I would first see how you intercooler cools, get some numbers of your IATs after its all hooked up and go from there with A/C. That said, I would consider running an electric fan(automotive, no more computer fans please :)) with a higher cfm if you decide to stack a/c and you intercooler.

Get some more baseline numbers and once you have everything record what you get after. Including A/c vent temps and such.

[Ether-D]

I think I'm gonna stack the a/c condensers and use one of them for the intercooler. 3/4 of the year, I don't use a/c anyway. And when I'm using a/c, I'm probably not gonna be beating on it (the car...). So, how should I stack them?

Intercooler first,

pros:
coolest air for intercooler
increased power
increased detonation protection

cons:
Greatly decreases the efficiency of the a/c whenever the a/c is on

A/c condenser first,

pros:
coolest a/c for all occasions

cons:
less intercooling on the hottest days (only when a/c is on)
increased detonation risk (only when a/c is on)
less power in the summer (only when a/c is on)

If the a/c is first, then it would be keeping the intercooler from cooling as well when a/c is on. But, when I want to have strong intercooling, I can just turn off the a/c and in 20-30 seconds, full power intercooling available. That's the solution I think. Thoughts?

[Ether-D]

True dat. I really want my whole car to retain that OE drivability. I want to get in, start it, and drive without any bs.

I'm trying to find a good spot for the external heat exchanger (hood scoop looked terrible, just terrible). So I was thinking about putting the 6x18x1.5" one next to the a/c condenser. There's almost enough room. I also thought of stacking two a/c condensers and using one for the intercooler, but I thought they would affect each other's efficiency. Dammit, I want ideal! Why can't ideal be my friend?

[The Dark Side of Will]

That's a pretty raucous engine, though... Not a fun drive when you get stuck in traffic.

[Ether-D]

Also, I think NA guys get 240chp out of a m20b28 relatively routinely. So I must be able to do that well. I would think.

And Will, I'm going to ebay now...

[The Dark Side of Will]

Oh lawd that looks expensive! I'll just do the 2.8 stroker by way of eta rods and m52 crank. It's at or around $1000 total in parts and machining. And I believe the compression ratio is a smidge lower than m20b25. Don't quote me.

Well... the way HE did it is expensive. You don't need the S52 crank, for example. The M54 unit will do fine. Check eBay out.

As Q5Quint mentioned, every extra cc you can get will help the supercharger work better.

Don't ditch your A/C. It gets just as hot in TN as it does in VA and I will never leave A/C out of a modified car... ever.

[Ether-D]

I am.... worried.... about where we can go with superchargers on m20s based off of other dyno results. The supercharged buick our charger came off of had 240hp and 280tq at 3600rpm at the crank..... but it was 3.8 liters. With mods it would hit 300hp.... but on our smaller 2.5 (or 2.8 if we stroke it out) I think the m90 has the flow in cfm, but it will struggle with the higher pressure ratio ie higher boost required to get those numbers on a smaller displacement engine.

Stock this thing ran 7-8psi on the buick, and with a pulley 11-12psi.... so 12psi on a smaller engine will be no problem but.... but on our smaller engine we will have smaller power. Looking at the efficiency charts~ I dont even think 15psi is actually an option as it is literally off the chart:


If we can hit 240 at the crank, like the buick, I think we will be in job well done territory. +70hp over stock is pretty good. I think the charger is good for more than that- maybe till 350hp based on flow... but you would need to use it on a 5.0 v8 or a 3.2l m engine for that due to leaving the efficiency zone of a 1.5x pressure ratio (8psi btw). After that we are creating more heat from inefficiency than we may be getting back in power.

However- More power to you for sticking with the m20! I didn't mean to come off as a negative nancy, I am just spoiled by $300 engines at a local pick n pull so it is hard to rebuild anything. Black friday deal = 1/2 any engine. 32v northstar or 1.6liter vw bug engine from 1969- they dont care lol.

I have a dollar on a 2.8l stroker m20 with a m90 and a cam hitting 240hp crank at 13psi, about what the buick was doing at 8psi. Most of that is just due to the smaller displacement/ pressure ratio efficiency thing.

I'm gonna hit 250chp, but the torque is what I'm loving. I can't wait to see the curve on this thing. I have 6psi now with the big pulley, and was faster (not bragging) than an m50 swap that I ran a bit with. That tells me that I must be at least 190chp (thinking this is conservative, btw). I want a torque monster with a long curve. That would be perfect for DD'ing. HP aint nuthin' but a number.

How much can heat be brought down with a large intercooler? Maybe get some heat efficiency back?

I'm thinking of "deleting" the A/C. I could just use the a/c condenser as the external heat exchanger for the intercooler. Perfect loation, fan attached with on/off button (a/c button) already installed, perfect size. It's killing me to think of getting rid of the a/c though. Somebody make this decision for me...

[Victell]

How much can heat be brought down with a large intercooler? Maybe get some heat efficiency back?

[Q5Quint]

I am.... worried.... about where we can go with superchargers on m20s based off of other dyno results. The supercharged buick our charger came off of had 240hp and 280tq at 3600rpm at the crank..... but it was 3.8 liters. With mods it would hit 300hp.... but on our smaller 2.5 (or 2.8 if we stroke it out) I think the m90 has the flow in cfm, but it will struggle with the higher pressure ratio ie higher boost required to get those numbers on a smaller displacement engine.

Stock this thing ran 7-8psi on the buick, and with a pulley 11-12psi.... so 12psi on a smaller engine will be no problem but.... but on our smaller engine we will have smaller power. Looking at the efficiency charts~ I dont even think 15psi is actually an option as it is literally off the chart:



If we can hit 240 at the crank, like the buick, I think we will be in job well done territory. +70hp over stock is pretty good. I think the charger is good for more than that- maybe till 350hp based on flow... but you would need to use it on a 5.0 v8 or a 3.2l m engine for that due to leaving the efficiency zone of a 1.5x pressure ratio (8psi btw). After that we are creating more heat from inefficiency than we may be getting back in power.

However- More power to you for sticking with the m20! I didn't mean to come off as a negative nancy, I am just spoiled by $300 engines at a local pick n pull so it is hard to rebuild anything. Black friday deal = 1/2 any engine. 32v northstar or 1.6liter vw bug engine from 1969- they dont care lol.

I have a dollar on a 2.8l stroker m20 with a m90 and a cam hitting 240hp crank at 13psi, about what the buick was doing at 8psi. Most of that is just due to the smaller displacement/ pressure ratio efficiency thing.

[Ether-D]

I'll do my full retort later, but I have no love for m50. None. I want to make a m20 that gets it's balls lovingly licked by m5xs.

[Q5Quint]

Don't quote me.... but would a m50 would be cheaper than that?

;-)

I think my e30 dreams look like this:

Get supercharger working on ratty 325is.
Ratty 325is eventually explodes or rusts away, or both.
Move supercharger bits over to clean e30 vert
if m20 ever explodes, swap to m50, make a new supercharger bracket.
drive for life, sex all day.

I should have started with a vert but there was a coupe for sale cheap literally just up the street from me. I think I would also m50 before a stroker- I am finding s50+tranny for about $2500 but I havent found any active sales yet. M50 seems to be about $500 lol

example of dreams + likely m3 fender hate:



If you are into building the stroker- go for it for sure. I love the m20 engine stock, but when you can drop in the m50 + cams for around the same price as a quality rebuild, and be moving again within a week, it is a hard argument to compare.

http://www.e30dohc.com/wiki/index.php?title=DOHC_Swap_Basics#What_Are_the_Required_Parts

[Ether-D]

Oh lawd that looks expensive! I'll just do the 2.8 stroker by way of eta rods and m52 crank. It's at or around $1000 total in parts and machining. And I believe the compression ratio is a smidge lower than m20b25. Don't quote me.

[The Dark Side of Will]

This is a pretty pricey one, but the M54B30 crank + rods and I'm not sure what pistons. The extra displacement will bump your compression ratio, so I'm not sure if a blower friendly build can be done with stock BMW pistons.

EDIT:

http://www.r3vlimited.com/board/showthread.php?t=317505

[Ether-D]

Does that mean just the crank, or the crank and rods? Cause I'd be down for whatever. If it's not that simple, what all is involved with a 3.0 build? Link?

[The Dark Side of Will]

If you're going to take the summer, why stop at 2.7 or 2.8? Brab an M54B30 rotating assembly and build a supercharged 3.0 ;)