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Schrick 304 vs 316


GazM3

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Hey chaps.

Just going through the selection process for the cam in my m10.

The engine has s14 crank currently 9.5:1 comp and dual dcoe45 carbs with 36mm chokes. I have also 38mm chokes I can use. I currently have an unknown origin cam of 300deg and 8.8mm lift. There is around 5mm piston to valve clerance currently.

My initial thoughts are to go with the 304 and take some thickness off the head and use a thin MLS gasket hopefully to get into the mid 10's on the comp. I'll use upgraded valve springs, retainers and use new rockers. I had a look at the 316 cam specs and it seems a lot more radical and it would need more comp again and definetly need some valve pockets grinded into the pistons.

How grumpy is the 316 cam and is it reasonably streetable with higher comp and the stroker crank. Is it too much cam for this combo. I don't want the engine like a 2stroke where it's got no power then all of a sudden it goes crazy.

Any advise will be welcome. Preferably good advise LOL. I don't mind a cammy idle but I don't want a car that has no power to 4000rpm.

Thanks in advance.

1974 2002 2.2stroker, DCOE45's, 300deg cam, 5 spd, 3.91 LSD // 1984 E24 M635csi, dogleg 5spd 3.23 LSD. // 1994 E34 540i, supercharged 16psi, 6spd E85 only, 3.15 LSD // 1997 E36 M3 Evo, low comp supercharged 18psi 6spd (under construction)

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I think there are a few unanswered questions here. Other than running a bigger cam and higher compression what else is not stock?

Do you have a stock flywheel? If you go with a 3i6 cam you lose drive ability under 3k rpm. If you lightened the flywheel your car won't idle. A 304 schrick cam is pretty aggressive as well. A schrick 292 is almost like an Alpina 300 cam.

You are in the racing realm at those levels and I think you defeat the purpose of having a street car. Additionally, running a "thinner" head gasket... Not sure how often you tear down your engine, but that's not the best way to increase compression.

Just my opinion

Rey

I'm a BMW Zombie and there's no cure!

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You might consider one of the Ireland Engineering cam grinds (in particular, the grinds they offer on a new billet). They have a grind which has very-similar lobes to the Schrick 304 but on factory lobe centers; meaning less overlap, which by general theory will result in improved low-end and idle though less top-end peak power.

 

As you surely know, an adjustable timing gear will be helpful in achieving correct valve timing when using the 'thinner' route. -KB

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I had a Schrick 304 with 40 DCOEs and appropriate pistons, etc and it was a lot of fun.  It idled like a '60's muscle car and didn't really make power until about 4500 rpm, but it was my daily driver and track car for awhile.  The 304 was a hoot to drive, and while I have never driven a 316, I don't think I'd want that much cam for a car driven on the street.

Ian
'76 M2

'02 325iT

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My 2.0L M10 engine, with 316 cam, 11.5 compression and 45 DCOE's (40 chokes) and full headers with 3" exhaust likes to live at 4,500-7,500 RPM. It's OK below that, and will easily pull 8,000 RPM on the dyno, but it is a race engine and I expect to freshen it every 80 hours or so. A 316 may be a bit much for reliable streetability. --Fred

 

EDIT: Good points below. Line boring the head for the 316 cam journal is not cheap, and race fuel needed for high compression. I run 100 octane (blend of 93 pump gas and 110 race fuel).

Edited by FB73tii

--Fred

'74tii (Colorado) track car

'69ti (Black/Red/Yellow) rolling resto track car

'73tii (Fjord....RIP)

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I ran a 316 on a 2 liter with a 12:1 compression ratio. I was running race fuel so it was not a daily driver but it had a lot of torque below 3000. I was running 40 mm chokes so you could not go to full throttle below 3500 but it was very drivable.

What head are you running? What pistons are you using to get 9.5:1 with the 84mm stroke crankshaft? What Bore are you running? If you are running a 121 head and a 90mm bore with flat top pistons you would be at 10:1 with a .051" thick gasket. If you are running a E12 head with the same bore and head gasket you would be at 8.6:1. If you were to shave 0.030 off the head (or combination of head and thinner gasket) you would bump the compression ratio by about .5

I don't recommend taking that much off the head/gasket as you will quickly have trouble dealing with cam chain tension, cam timing is doable with an adjustable gear.

I ran a 316 on a 2 liter with a 12:1 compression ratio. I was running race fuel so it was not a daily driver but it had a lot of torque below 3000. I was running 40 mm chokes so you could not go to full throttle below 3500 but it was very drivable.

What head are you running? What pistons are you using to get 9.5:1 with the 84mm stroke crankshaft? What Bore are you running? If you are running a 121 head and a 90mm bore with flat top pistons you would be at 10:1 with a .051" thick gasket. If you are running a E12 head with the same bore and head gasket you would be at 8.6:1. If you were to shave 0.030 off the head (or combination of head and thinner gasket) you would bump the compression ratio by about .5

I don't recommend taking that much off the head/gasket as you will quickly have trouble dealing with cam chain tension, cam timing is doable with an adjustable gear.

1970 1602 (purchased 12/1974)

1974 2002 Turbo

1988 M5

1986 Euro 325iC

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Hey chaps. Thanks for all the quick and thorough responses. I'm pretty new to the m10 and the advice is invaluable. The engine has been recently rebuilt which states 9.5:1 compression. But it uses the e12 head so if it measures a lowly 8.6:1 I will have no options but to run aftermarket pistons to get compression high enough to use even the 304 cam. The setup needs compression to give the bigger cams reasonable torque below 4000rpm. We have ron98 fuel here (equiverlant to mon94) so high 10's to low 11's is quite doable if the cam is large enough to make use of it. Good points about taking too much off the head and keeping the tension in the timing chain. No problem getting the journals bored larger for te 316 but it looks a massive step up from the 304 so it will probably be a little over the top for a street engine it seems even with the stroker I'm more leaning to the 304 but there is nothing worse than wishing u went 1 size up on the cam once u put it in.

I will check the compression that I have now and go from there. If I have 9.5:1 currently the dillema is there but it sounds like pistons is the way to go regardless.

1974 2002 2.2stroker, DCOE45's, 300deg cam, 5 spd, 3.91 LSD // 1984 E24 M635csi, dogleg 5spd 3.23 LSD. // 1994 E34 540i, supercharged 16psi, 6spd E85 only, 3.15 LSD // 1997 E36 M3 Evo, low comp supercharged 18psi 6spd (under construction)

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I am just wondering what pistons they used, they had to be custom made because of the increased stroke of the S14 crank. They would have to move the wrist pin in the piston to keep the piston below the deck on the block at TDC. If they put a dome on it I am sure 9.5 would not take much of a dome to get there. If you are going to run much more than a 304 you really need to think about some port work to take advantage of the cam. Also think about the exhaust header and the rest of the system.

1970 1602 (purchased 12/1974)

1974 2002 Turbo

1988 M5

1986 Euro 325iC

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I am running the Schrick 304, a 121 head, an 84 mm stroke S14 crank and flat top pistons. The compression ratio is about 9,5 to 1. There is also an aluminum flywheel.

I started out with a 38/38 Weber but then changed to Megasquirt FI and the curved intake manifold out of an E21. The engine runs great with either fuel-setup and has lots of torque from 1500 RPM on up; but in stop and go traffic it is a pain. A steel flywheeI might be the cure for that, but I like the throttle response of the light flywheel.

I would not recommend the 316 deg cam for the street.

BTW, I could not tell any difference in power or drivability when I changed from the 38/38 to the Megasquirt. However, with the FI the gas mileage is much better. 

Edited by allbim

No amount of skill or education will ever replace dumb luck
1971 2002 (much modified rocket),  1987 635CSI (beauty),  

2000 323i,  1996 Silverado Pickup (very useful)

Too many cars.

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yes the light flywheel is a pain in traffic.  You cant have it both ways.  Im not even sure what sort of flywheel is in the 2002.  

The head is getting upgraded ports with work mainy at the top section of the port area.  Im getting the ports matched to the intake manifold and the carbs.  This is what started the snowballing effect of the upgrading works.  The carbs were about 5-6mm bigger port than the manifold!!

 

I dont mind abit of nastyness with the idle, but I dont want the car to shake like crazy at idle either. 

 

With the fuel we have here available to us 9.5:1 wont be enough comp to take full advantage of the cam.  Ive been in a few even moderatly powered engines with high compression and they are just fantastic to drive, they have that real nasty edge to the power, and speaking generally here, the high comp seems to calm the behavior of the bigger cams somewhat. Its looking more likely to swap pistons to gain the comp, so I guess I can go reasonably high on the comp.  Was thinking 11.0:1 with the 304 and 11.5:1 with the 316.  I can get pistons from PPM here in Melbourne.  They done my 13.5:1 ones with the valve relief cuts for my M88/3 setup Im accumilating bits for.  

 

One other tangent I thought of are the roller cam with those rockers discussed on the web.  It seems they are not currently available or they have stalled.  This would give the best of both worlds, but I guess the problem could be cost and where does it all  end.  At the end of the day all I really wanted was around 160-170bhp.  Any more is a bonus really.

 

Thanks again for your help, its been invaluable.

1974 2002 2.2stroker, DCOE45's, 300deg cam, 5 spd, 3.91 LSD // 1984 E24 M635csi, dogleg 5spd 3.23 LSD. // 1994 E34 540i, supercharged 16psi, 6spd E85 only, 3.15 LSD // 1997 E36 M3 Evo, low comp supercharged 18psi 6spd (under construction)

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I had a Schrick 304 with 40 DCOEs and appropriate pistons, etc and it was a lot of fun.  It idled like a '60's muscle car and didn't really make power until about 4500 rpm, but it was my daily driver and track car for awhile.  The 304 was a hoot to drive, and while I have never driven a 316, I don't think I'd want that much cam for a car driven on the street.

What he said.  Rump, rump, rump!  Mine always gets looks at the stoplight, particularly from those little Japanese cars with silly "waaaaah" exhausts!

74 Amazonas tii, Bill Holman built, dual throttle bodies, Shrick 304, Stahl header, five speed, big brakes, H&R springs, Bilsteins, E30 BBS wheels.

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I have run both the Shrick 304 and 316 cams extensively in my race car. The 304 is a bitchen cam and I highly recommend it for 10:1 compression. I was surprised at how well it idled. The 316 is a whole nother animal, I run it with 13:1 compression, 48 Side drafts, and surprisingly little porting and pull 175+hp at the dyno. The bad news, for a street car, is that the torque (150 ft-lbs) does not kick in until about 4900 rpm.

Get the Shrick 304, you will love it! 

Mark

post-35652-0-11894600-1438324990_thumb.j

73tii

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Thanks for the advise there.

I assume the 316 still gives reasonable torque below 4900 but with 13:1 comp it will maximise the results. With low 11's it will be more 2stroke like perhaps.

It wouldn't be good in a 'street' car with the peak torque around 5k mark. We are opening up the ports extensively at the top where the high velocities are.

11320061-5282-435F-B7C7-3F2DD1062D19.jpg

There's a pic of the beginnings of the head porting.

Yes with the right timing and some added fuel it should idle pretty good with the 304.

It's a pity there is no cam between the 304 and 316. I may sneak a look at catcams catalog.

1974 2002 2.2stroker, DCOE45's, 300deg cam, 5 spd, 3.91 LSD // 1984 E24 M635csi, dogleg 5spd 3.23 LSD. // 1994 E34 540i, supercharged 16psi, 6spd E85 only, 3.15 LSD // 1997 E36 M3 Evo, low comp supercharged 18psi 6spd (under construction)

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