m20b32 11.0:1 CR cam selection

[doktor_b]

i did search and i've been reading and reading.

however, i haven't seen many builds like mine so i'm hoping some of you more experienced r3v users will chime in with some advice.

Full IE 3.2L stroker kit
86mm pistons with oversize valve reliefs for o/s valves and high lift cam
89.6mm stroke
135mm H-beam rods
+1mm intake and exhaust valves
IE HD rockers
VAC springs and retainers
30# gen 3 bosch injectors from MaksInjection
MS2 setup from whodwho with wasted spark (LS coils) and semi-sequential injection and MAP based fueling. (that horrid AFM is going in the recycling bin asap)

i was going to run the 272 in my current m20 but it has [who knows] how many miles on it. and i don't want to run the risk of cam-related issues. my plan was to run that 272 for one season, and then upgrade to a 304 and 40mm ITBs. however, i think i'm going to keep the stock manifold (port-matched and extrude honed) and just work on other aspects of the car instead of spending the money on ITBs. (i plan to drive this car to work as well as the track)

so here's my dilemma.
spend the money for a Schrick 288 or go with an IE 272 or an IE 304?

this car will see traffic. this car will see a lot of miles. i'm going big because i want torque, but i don't want to build a tractor motor. (any more than an m20 is a tractor motor to begin with)

thanks in advance.

[tinkerputzer]

I would go for the schrick 288 over the others. The schrick 284/272 is also a good compromise cam, but it will fall short of the 288 on top. I went with it for my dd for CA emissions reasons.

Looking at your list of parts you are off to a good start. I would add an adjustable cam gear to the list too.

I'd skip the extrude honed manifold and get a decent set of headers. Bullet Ride is offering another group buy on the "bav auto" headers. They are excellent quality and are bolt on if you get them with the mid-pipes.

Here are a couple threads that might help you:

http://www.e30tech.com/forum/showthread.php?t=116074

http://e30tech.com/forum/showthread.php?t=115574

[doktor_b]

i have a set of headers on the car currently. they'll have to make due til i can afford some nicer ones. i'm not certain what brand of header i have currently, but they sound decent and they don't leak. (and i've had them red hot before)

i've been shopping cam gears. haven't made a final decision on which one i'll end up with. i'll probably end up with the VAC as it looks real nice and i haven't heard any horror stories about it moving or skipping belts. however, a cam gear isn't 100% necessary to get this build running. so it can wait til closer to spring. (i'm hoping to receive the rotating assembly by 12/17. so i'm shooting for a february first start-up of the new engine.)

i'll check out those links and see what's what.

thanks for the insight.

[nando]

the 288 would be a good choice. with the big bottom end you won't notice any loss in low end torque since the baseline number will be higher than the stock motor's peak.

I'd do some heavy research on building the head. I would skip the EH intake as well - for that price, you don't gain much. you'd be better off saving for good ITBs (not Dbilias), as that's something you can buy later and with that cam, should wake up the motor quite a bit.

as it is, the stock TB and intake will be a restriction on your motor. you'll want to deal with that somehow and the stock manifold won't help much even if it's been extrude honed.

[tinkerputzer]

You're right about the cam gear not being completely necessary to get it running but it is completely necessary to get the most out of what you're running ;)

[pantelones]

30# gen 3 bosch injectors from MaksInjection

this car will see traffic. i'm going big because i want torque, but i don't want to build a tractor motor.

Someone correct me if I'm wrong, but 30# are probably too large... Using the "simple calculator" at the bottom of this site...

http://www.rceng.com/technical.aspx

Using 250Bhp, 6Cyl, .5 BSFC, 80% duty cycle, and 43.5 PSIG I got 26.19Lbs/Hr or 275CC/Min


As for the cam, that is really determined on what you want out of the motor... The 304 is pretty much out of the equation if you want to retain torque, but the 288 could be useable since you have the compression bump, and the liter bump. Also as mentioned above, forget the extruded-honed intake... Buy a set of headers! The Bavauto copies in the group buy have 1 3/8" primaries that may be too small; I just saw that I.E. came out with a very similar header but with 1 1/2" primaries that might work better. Both are long tube designs that will help out torque, but will restrict top end HP.

[ForcedFirebird]

Someone correct me if I'm wrong, but 30# are probably too large... Using the "simple calculator" at the bottom of this site...

http://www.rceng.com/technical.aspx

Using 250Bhp, 6Cyl, .5 BSFC, 80% duty cycle, and 43.5 PSIG I got 26.19Lbs/Hr or 275CC/Min


As for the cam, that is really determined on what you want out of the motor... The 304 is pretty much out of the equation if you want to retain torque, but the 288 could be useable since you have the compression bump, and the liter bump. Also as mentioned above, forget the extruded-honed intake... Buy a set of headers! The Bavauto copies in the group buy have 1 3/8" primaries that may be too small; I just saw that I.E. came out with a very similar header but with 1 1/2" primaries that might work better. Both are long tube designs that will help out torque, but will restrict top end HP.

Take those calculators with a grain of salt for BMW engines. Dyno tuned a 413 ECU with 223 to the wheels with stock m50 injectors and had plenty room left in the maps with a 12.5 WOT AFR.

EDIT: That calculator says the injectors would need to be 23lb injectors to make 223 at the crank.

[doktor_b]

the 288 would be a good choice. with the big bottom end you won't notice any loss in low end torque since the baseline number will be higher than the stock motor's peak.

I'd do some heavy research on building the head. I would skip the EH intake as well - for that price, you don't gain much. you'd be better off saving for good ITBs (not Dbilias), as that's something you can buy later and with that cam, should wake up the motor quite a bit.

as it is, the stock TB and intake will be a restriction on your motor. you'll want to deal with that somehow and the stock manifold won't help much even if it's been extrude honed.

thanks! you said pretty much what i expected to hear about the intake and TB. looks like the ITBs will go back on the 'next year' list.

You're right about the cam gear not being completely necessary to get it running but it is completely necessary to get the most out of what you're running ;)

absolutely.
*side note. both the threads you linked above are what helped me decide to go big NA m20 and not boost my car. excellent stuff in there!

Someone correct me if I'm wrong, but 30# are probably too large... Using the "simple calculator" at the bottom of this site...

http://www.rceng.com/technical.aspx

Using 250Bhp, 6Cyl, .5 BSFC, 80% duty cycle, and 43.5 PSIG I got 26.19Lbs/Hr or 275CC/Min


As for the cam, that is really determined on what you want out of the motor... The 304 is pretty much out of the equation if you want to retain torque, but the 288 could be useable since you have the compression bump, and the liter bump. Also as mentioned above, forget the extruded-honed intake... Buy a set of headers! The Bavauto copies in the group buy have 1 3/8" primaries that may be too small; I just saw that I.E. came out with a very similar header but with 1 1/2" primaries that might work better. Both are long tube designs that will help out torque, but will restrict top end HP.

my header are the shape of the BavAuto headers. i'm not certain if they're genuine or not and i'll have to check the diameter of the primaries. but they're def on the list of things to be replaced after i get the new engine in and running.

Take those calculators with a grain of salt for BMW engines. Dyno tuned a 413 ECU with 223 to the wheels with stock m50 injectors and had plenty room left in the maps with a 12.5 WOT AFR.

EDIT: That calculator says the injectors would need to be 23lb injectors to make 223 at the crank.

my goal is ~210-230whp now and ~240whp on ITBs. assuming 20% for drivetrain loss, that puts my final goal nearing 300chp. the injector calculators are all based on chp, so i used conservative numbers (round up for hp, mostly) and came up with 30# injectors. i figure with the MS, i'll be able to dial down the pulsewidth initially and then bring it up as the tune, and my remaining components, improves. if they're to big, i'll find out in tuning and go with something appropriately sized based on my findings then.

this seemed a safer route than (and initially cheaper) than going with smaller injectors, an adjustable reg, and dialing up the pressure to make up for flow at 3Bar.

and i hate changing fuel injectors. gas everywhere, tight spaces, big hands, meh. rather err on the big side and dial them down.

[pantelones]

Take those calculators with a grain of salt for BMW engines. Dyno tuned a 413 ECU with 223 to the wheels with stock m50 injectors and had plenty room left in the maps with a 12.5 WOT AFR.

EDIT: That calculator says the injectors would need to be 23lb injectors to make 223 at the crank.

Your referring to the 17Lb green tops right? So yeah... 30's are huge! I knew that s52's can make around 230Whp with the 21.5Lb pink tops, but could think of where to reference that...

[ForcedFirebird]

my goal is ~210-230whp now and ~240whp on ITBs. assuming 20% for drivetrain loss, that puts my final goal nearing 300chp. the injector calculators are all based on chp, so i used conservative numbers (round up for hp, mostly) and came up with 30# injectors. i figure with the MS, i'll be able to dial down the pulsewidth initially and then bring it up as the tune, and my remaining components, improves. if they're to big, i'll find out in tuning and go with something appropriately sized based on my findings then.

this seemed a safer route than (and initially cheaper) than going with smaller injectors, an adjustable reg, and dialing up the pressure to make up for flow at 3Bar.

and i hate changing fuel injectors. gas everywhere, tight spaces, big hands, meh. rather err on the big side and dial them down.

You will be fine with them and MS. Tuned a stock N/A m20 M1.3 with 36lb injectors and it idles/drives fine and fuel consumption is normal. The comment wasn't really aimed at your injector selection.

I have run 27's in my m20's in the past, only because I had a pile of them and the spray pattern is much nicer on the newer injectors. My fuel mileage actually went up (could have been the tune as well).

Your referring to the 17Lb green tops right? So yeah... 30's are huge! I knew that s52's can make around 230Whp with the 21.5Lb pink tops, but could think of where to reference that...

Tuned s52's make more than that ;) Yes, green m50 injectors.

[tinkerputzer]

There's no harm in running bigger injectors as long as you have the ability to control them. Hell i think nando ran 42 lb/hr in his 2.7 with out issues. My 30 lb/hr run around 65% duty cycle at redline.

[digger]

you wouldn't want a 304 with the standard manifold driveability will suffer and 272 might be slightly too small for the compression

[Doktor_BS]

I remember when I thought I had a "racecar"...oh and i thought my car was "Low" get real.

[LJ851]

I remember when I thought I had a "racecar"...oh and i thought my car was "Low" get real.

Great first post !

[nando]

There's no harm in running bigger injectors as long as you have the ability to control them. Hell i think nando ran 42 lb/hr in his 2.7 with out issues. My 30 lb/hr run around 65% duty cycle at redline.

I did, but it runs way better with 24# injectors.

The correct answer is to use injectors sized just right, and 30# aren't it.