Yet another request for advice on a stroker

[Gavin]

I’ve got an 88 325 (super ETA) and I’m looking to either tear it down and rebuild it, or buy a 2’nd engine and rebuild that, in the near future. I want to build a bored and stroked motor and would like to confirm that I’ve got the correct parts and processes in mind.

I’ll start out explaining my performance expectations: I’m looking for 220WHP, >200WTQ, and good NA reliability. I also don’t want to have to rev over 7000 RPM.

I’m looking to buy:

• MM 86mm high-compression pistons (obviously I’m planning to bore out my cylinders to 86mm)
• 135mm forged H beam rods, or E36 M3 135mm rods
• E30 325i head
• MM dual valve springs
• 1mm oversized valves
• MM valve guides and seals
• 272/284 cam
• Peened rocker arms

I’ll reuse my 81mm SETA crank, but replace all the bearings and fasteners of-course. I plan to port, polish, & port match manifolds to the 325i head (and will send it out for machining to take the larger valves). As the icing on the cake I’m putting together an ITB system as well. My intension is to use a MSII computer to take care of fueling and spark duties.

Q- What compression ratio is appropriate? I was hoping for 10.5:1 but I’ve read here in the forums that may be too high for normally available premium fuel, would polishing out hot-spots in the combustion chamber allow me to run higher compression?
Q- Are the H beam rods worth the $$
Q- Is a high capacity oil pump worth the $$
Q- Am I missing anything?

I suppose I could do without all the valve-train goodies, but it’s my feeling that the head is what really keeps the cork on my engine. I may do everything but the head work as a 1’st step and see how I like that before I spend all that money on my top end.

[StereoInstaller1]

I’m looking for 220WHP, >200WTQ, and good NA reliability. I also don’t want to have to rev over 7000 RPM.

I’m looking to buy:

• A good condition M52 or M30B35

Fixed your post for ya....
Luke

[Gavin]

Na, I’m not looking to swap. More potential overall, but dollar for dollar I think the build up is a better option. And I wind up with a rebuilt motor rather than a new used engine.

Either way ‘swap vs. stroke’ has been discussed to death. I’d like to keep this thread on the topic of build up please.

[StereoInstaller1]

I know it is possible to make a 220whp M20, but I would be amazed to see it at 2.8l. I would love to see a homemade ITB setup, or even a sheetmetal intake manifold with maybe 3 TB's. Considering the huge limitation of the M20 head, it would have to be a truly thorough build, using much larger displacement than you are gonna get on a SETA crank.

Your plan is damn near identical to mine, except I am thinking TECIIIr or VEMS rather than MS&S. I am hoping for 185whp, using stock SETA pistons.

Believe me, I would love to see someone do a real world "budget" 220whp M20. The head is such a turd though, it just isn't likely.

Good luck, though. I really do hope you succeed!
Luke

[digger]

What ever you do don't get a M50 how boring you'll still only have 2.5L

You realistically won't get a real 220whp using 81mm crank revving below 7000rpm the 12V head won't allow it. If you want power you need a wild head and rpm and more capacity.

Don't get +1 valves they can shroud the head and impede flow (particulary the intake valves)

MM don't have dual valve springs they have their custom springs which are singles good for atlast 8000rpm but need their own retainers to work.
High comp pistons will be fine with decent fuel (you can get a chip from MM if you are worried).

i have actually bought MM 11:1 comp pistons, M3 89.6mm crank, Forged 138mm rods, ARP rod bolts head bolts and main studs, Race Head and will be dropping in a engine in a few months along with ported intake manifold, Zone BBTB, BTB extractors, nology wires, M30 AFM, MM chip, Piggyback, lightweight flywheel. So we'll see what the M20 is capable of.

[ColdAccord]

220whp and you will spend a ton of money

I've spent probably a tad under 3k already and will have probably 195whp

I have custom 10.2:1 pistons ~$600
283 cam, valve springs, rocker arms and shafts ~650
cyl head work, including 3 angle valve job ~250
stm6 (dont remember what i paid but lets say) ~$300
honing and decking block
clutch
light flywheel
2.7 crank and rods
need to buy an maf
all the misc crap that REALLY adds up

and if I want more power I'd have to dump serious $ on a dbilas setup

if I were to do it all over again I'd just dump the 5k on a euro s5x. 280hp stock, with some mods can get into the 300s.

[digger]

220whp and you will spend a ton of money

I've spent probably a tad under 3k already and will have probably 195whp

I have custom 10.2:1 pistons ~$600
283 cam, valve springs, rocker arms and shafts ~650
cyl head work, including 3 angle valve job ~250
stm6 (dont remember what i paid but lets say) ~$300
honing and decking block
clutch
light flywheel
2.7 crank and rods
need to buy an maf
all the misc crap that REALLY adds up

and if I want more power I'd have to dump serious $ on a dbilas setup

if I were to do it all over again I'd just dump the 5k on a euro s5x. 280hp stock, with some mods can get into the 300s.

where is your dyno plot? No offense but there doesn't seem to be 195whp worth in those mods?

[JRowe]

I'll buy your s-eta pistons if they're in good condition and you don't plan to use them.

[nando]

I’ll start out explaining my performance expectations: I’m looking for 220WHP, >200WTQ, and good NA reliability. I also don’t want to have to rev over 7000 RPM.

Q- What compression ratio is appropriate? I was hoping for 10.5:1 but I’ve read here in the forums that may be too high for normally available premium fuel, would polishing out hot-spots in the combustion chamber allow me to run higher compression?
Q- Are the H beam rods worth the $$
Q- Is a high capacity oil pump worth the $$
Q- Am I missing anything?

220whp isn't easy, but it can be done. you'll also need a nice set of headers capable of increasing exhaust gas velocity, and you definitely need to do something about the intake.

are you having MM machine your head? I figured out that after all I spent on my head doing it myself, I could have had MM build me a head (they CNC the ports, you aren't going to be able to match that at home) for only $500 more.

for your questions, the MM pistons are only available in 2 compression ratios: 10:1 and 11:1. forget about what you read elsewhere about compression and M20 heads, because it's built into the design of the MM pistons. the two biggest reasons the MM pistons can work with more timing advanced and high compression are the 86mm bore and better piston cooling. I'd love to have the 11:1 pistons instead of what I have, but then my engine would still be an interference design - the 10:1 pistons allow for much deeper valve pockets.

for rods, the H beams probably aren't worth the money unless you are going with their 3000 kit with the 84mm crank. and realistically, if you want 220whp, I think you are better off using their 84mm crank and rods (you have to use their rods with the 84mm crank because they are a different length). that's probably the only thing I wish I'd changed on my motor, but I can't really complain as is.

the high capacity oil pump is probably overkill on a street motor. a new factory oil pump should be sufficient - it actually supplies too much pressure to the motor anyway (go read up on the shortcomings of M20 oiling sometime).

you are right that the head will be a limiting point, but you can't just port the head and add a cam and expect it to flow more - because the rest of the intake system is still designed for a stock M20. I can definitely tell my engine is being choked by the stock intake manifold, AFM, and airbox - but I love the way my motor runs as is, so I'm holding out on any intake modifications until I get afford something really worthwhile (like ITBS).

if you are really going to use ITBs, then you might consider a more agressive cam - say a 288 or 292. one of the biggest advantages of ITBs is you can run a more agressive cam without having ildle problems.

and good headers are also more important than people think - go look at what #s the guys are getting out of their M20s on www.e30zone.co.uk. the guys in south africa do pretty well too (although they can still get leaded fuel there).

keep in mind that the MM engines are designed to use stock computers, intakes and exhausts - so they have quite a bit more potential.

when you have it all put together and running, come back and tell us what you think - I bet you will be pretty happy. I'm still running on the stock computer (with a chip) and 100% completely stock intake system, and I wouldn't even think of trading my M20 for an M50 swapped car!

[nando]

What ever you do don't get a M50 how boring you'll still only have 2.5L

You realistically won't get a real 220whp using 81mm crank revving below 7000rpm the 12V head won't allow it. If you want power you need a wild head and rpm and more capacity.

Don't get +1 valves they can shroud the head and impede flow (particulary the intake valves)

MM don't have dual valve springs they have their custom springs which are singles good for atlast 8000rpm but need their own retainers to work.
High comp pistons will be fine with decent fuel (you can get a chip from MM if you are worried).

i have actually bought MM 11:1 comp pistons, M3 89.6mm crank, Forged 138mm rods, ARP rod bolts head bolts and main studs, Race Head and will be dropping in a engine in a few months along with ported intake manifold, Zone BBTB, BTB extractors, nology wires, M30 AFM, MM chip, Piggyback, lightweight flywheel. So we'll see what the M20 is capable of.

I agree on the valves, they are also way too expensive to be worth it. a quality porting job done by somebody who knows M20s would be worth much more than +1 valves.

that's a pretty nasty M20 build there too! mine was more of a "budget" stroker (since I used a "free" 81mm crank and $200 E36 M3 rods), but I'd love to do a full out 3.2 like yours someday. when I get my car on the dyno we'll all have to compare our setups!

[Gavin]

JRowe, when I pop out the SETA pistons I'll be sure to drop you a line. This is likely to be a long process for me though, so I wouldn’t hold my breath if I were you.

Nando, I wasn’t planning on having MM do up my head. I’ve done it once before and am looking forward to doing it again, but it’s definitely worth seeing what they can do for me. And yes ITB's are on my menu as well, first item on the menu actually; I've got all the hardware I need for a custom set-up already (save for a fuel piggy-back), I just need to start cutting and welding (and endlessly fabricating until I wish I were dead).

Digger, I figured that combined with the 2mm overbore I have planned the +1mm valves would do my head some good. Is anyone around here using the +1 valves to know for sure what, if any, gains they offer?

I’m glad to hear opinion that a more aggressive cam is doable, and if the H beam rods aren’t really required I’ll save some $$ and go for the E36 M3 rods, also good to hear that a stock oil pump should suffice. Thanks for the advice so far guys, keep it coming.

It seems as though my 220 WHP goal may be unrealistic for the set-up I have in mind, but I’m looking forward to seeing what I can do with a high compression 2.8L stroker with ITB’s.

[digger]

JRowe, when I pop out the SETA pistons I'll be sure to drop you a line. This is likely to be a long process for me though, so I wouldn’t hold my breath if I were you.

Nando, I wasn’t planning on having MM do up my head. I’ve done it once before and am looking forward to doing it again, but it’s definitely worth seeing what they can do for me. And yes ITB's are on my menu as well, first item on the menu actually; I've got all the hardware I need for a custom set-up already (save for a fuel piggy-back), I just need to start cutting and welding (and endlessly fabricating until I wish I were dead).

Digger, I figured that combined with the 2mm overbore I have planned the +1mm valves would do my head some good. Is anyone around here using the +1 valves to know for sure what, if any, gains they offer?

I’m glad to hear opinion that a more aggressive cam is doable, and if the H beam rods aren’t really required I’ll save some $$ and go for the E36 M3 rods, also good to hear that a stock oil pump should suffice. Thanks for the advice so far guys, keep it coming.

It seems as though my 220 WHP goal may be unrealistic for the set-up I have in mind, but I’m looking forward to seeing what I can do with a high compression 2.8L stroker with ITB’s.

SAe30 uses bigger valves on exhaust side and makes good power but you don't know whther its the valves or something else. MM use standard valve sizes so they should be fine. Bigger valves adds valve train mass too.

[StereoInstaller1]

Wow, Gavin, seems like a ton of work for a "maybe". I just want you to get cracking on it so we can all "know".

My understanding with the Dbilias ITB's is that they basically add about 10% to whatever build you have...so if you were rocking 180hp on a M20 intake mani, you should get to 198, right? (YMMV, of course).

Luke

[SA E30]

SAe30 uses bigger valves on exhaust side and makes good power but you don't know whther its the valves or something else. MM use standard valve sizes so they should be fine. Bigger valves adds valve train mass too.

I use bigger valves all the way around... but the valve sizes are matched, which helps with midrange power.

The only reason I went with bigger valves was that I was already going to be making the exhaust valve the same diameter as the intake, so why not go the whole hog.

IMO, the stroker u seem 2 be building u wont really need the bigger valves, money would be better spent on a good head job and camshaft...

Make sure who ever does your porting doesn't open up the ports to much as u would be losing air speed, which reduces low end and midrange power...

Nando, we actually dont get Leaded here anymore, was phased out at the beginning of the year... but My car runs on 102.6 Leaded race fuel and toulene (making it about 110 octane), it's going to be replaced later in the year with 100 octane Unleaded race fuel... nothing adding more toulene can't fix :)

[nando]

yeah, there's no way I could afford to run that kind of fuel in my street car. there's a reason I have 10:1 compression and you have almost 13:1 :D