N/A aftermarket rods?

[mr2peak]

I have personally built many m20's, one having almost identical specs. No, you won't be making any power at 7500rpm - definitely not with that cam it's too small - I would suggest the new IE grind. 300 to the wheels don't need rods, anyways. Digger made a good suggestion with the 24v rods. They are lighter and about the same strength. Stock rods have shown me that 350+whp is a non issue, m20 or 24v. Spend your money on machining. Weight match everything, balance, deck, align bore, high speed balance assy, and recon rods.

Make sure you head porter knows what he is doing, or you run a good chance of gaining nothing or more likely, hurting flow. Don't even touch them without a flow bench. We flowed many "ported" heads.

Cam is 272 new billet, I have no need for an very high-strung M20. It's going in a convertible so the torque is welcome. I want (and need) a block and head that can pass smog, and last the next 150k miles. 2.9 over 3.1 due to the wrist pin/oil ring issues on a 3.1. A bigger cam will definitely net more overall power, but that isn't the only goal here. If it was, I would be swapping. If I really want to go fast, I'll take the '01 M Coupe for a drive :)

I did the porting, using only sandpaper rolls. Very very lightly blended in the runners with the bowls, and polished the exhaust side. Blended the seats into the bowls. Gasket matched everything. I made sure to remove minimal material. I've heard it's really hard to get even 5% more flow from these heads, so I focused only on the very obvious. Machinist said I did a good job, hope he wasn't just stroking my ego.

The whole thing will be matched, balanced, etc. Skipping machine work is the last place I want to try and save money.

Ended up getting the Tuscan rods. Cassidy weighed them for me @529g with ARP2000 bolts installed. Bolts weigh 27g each. Lightest rods available without spending significantly more money. They also have rifling, so I can avoid installing oil squirters and save costs there. Also don't have to purchase and recondition S52/M52 rods, so for a few hundred more I'm happy. They are significantly discounted right now, so that is good.

[digger]

what issues are there on wrist pin oiling issues?

[mr2peak]

None, but with $1200 pistons I'd rather be safe. I'll be running a crank scraper as well, so there's a bit less oil flying around than usual. I'm future-proofing more than anything, I'm sure I'll want to turbo this car eventually.

[ForcedFirebird]

We made 202wtq with the 272, and am sure it would be more with the 284, believe it or not - 272 is barely bigger than stock. IE has a new "billet" grind (http://www.iemotorsport.com/bmw/E30-...cam284280.html). Neither cam is billet, just new castings BTW - billet would start at about $800 for a blank as we can get them for the GM v6's. The engine we did this year was a 2.8 and ~9.4-ish compression. Ended up 217whp/202wtq, but that was just to see best peak. Tuning under the curve netted 202/198 peak, but overall power was better (both runner length and ECU tuning were done on a dyno).

Apologies for being frank, but: As far as the head porting, your machine shop doesn't know jack. You can't tell by eye, and we even have to test our heads after since they are so sensitive - specially with stock valves. There's a lot to be said in the seat angles and back cut, 99% of the population has no idea what they are looking at as far as a port job, never mind an m20. There's bumps and angles in the port that I feel designed to be there. It took us multiple seat angle testing to have custom seat cutters made as the machine shops using "standard" cutters were ruing heads.

**steps my short butt off the soap box** lol

Should be a strong runner, regardless, we only see about 4-8%whp difference on the engines we tested (porting only), but have yet to do an m20 back to back. Not worth the time lately, small staff and shop is always full - was easier to do when this wasn't a full time job. :(

[whitebulat22]

We made 202wtq with the 272, and am sure it would be more with the 284, believe it or not - 272 is barely bigger than stock. IE has a new "billet" grind (http://www.iemotorsport.com/bmw/E30-...cam284280.html). Neither cam is billet, just new castings BTW - billet would start at about $800 for a blank as we can get them for the GM v6's. The engine we did this year was a 2.8 and ~9.4-ish compression. Ended up 217whp/202wtq, but that was just to see best peak. Tuning under the curve netted 214/198 peak, but overall power was better (both runner length and ECU tuning were done on a dyno).

I think it was 214 not 202.

General question related to thread is there any way of simulating how much extra power a light rod will save at high revs? I'm planning to do basically the exact same thing as the OP, but I already have IE forged rods and m52 rods, leaning towards keeping the m52 ones and trading the forged ones towards flywheels / itb fund etc.

[ForcedFirebird]

I think it was 214 not 202.

General question related to thread is there any way of simulating how much extra power a light rod will save at high revs? I'm planning to do basically the exact same thing as the OP, but I already have IE forged rods and m52 rods, leaning towards keeping the m52 ones and trading the forged ones towards flywheels / itb fund etc.

You are correct sir, lol. Final TQ was better than the post in this thread as well. That car was on the dyno a lot with the head cracking and all, easy to get confused. Was late last night and we had a long day driving home from the holiday...Either way, this is an excellent combination for not a big bundle of cash. Car is now up for sale, owner is middle aged and just had a child, he was ready to go bigger cam and taller gears too. :(

Had some fun today at the dyno. Made a best peak hp @ 217, but that was with the runners shortened and mid range TQ suffered. Overall best "power under the curve" was a peak of 214hp/202tq.

Sorting the graphs, will post some up.

[mr2peak]

Apologies for being frank, but: As far as the head porting, your machine shop doesn't know jack. You can't tell by eye, and we even have to test our heads after since they are so sensitive - specially with stock valves. There's a lot to be said in the seat angles and back cut, 99% of the population has no idea what they are looking at as far as a port job, never mind an m20. There's bumps and angles in the port that I feel designed to be there. It took us multiple seat angle testing to have custom seat cutters made as the machine shops using "standard" cutters were ruing heads.

**steps my short butt off the soap box** lol

Should be a strong runner, regardless, we only see about 4-8%whp difference on the engines we tested (porting only), but have yet to do an m20 back to back. Not worth the time lately, small staff and shop is always full - was easier to do when this wasn't a full time job. :(

No offense taken, I know you're correct. Stock is 264, so 272 should be near, or basically the same as stock on the larger displacement. Far from aggressive. As for the headwork, I did have guidance from a BMW tech who's owned and raced many e30's over the years (and was my boss for a while) so it's more than just a crap-shoot in the dark. I'm know Rama would do a better job building the head to match the ITB's, but I enjoyed doing it myself; life-enrichment is one of the main goals here.

General question related to thread is there any way of simulating how much extra power a light rod will save at high revs? I'm planning to do basically the exact same thing as the OP, but I already have IE forged rods and m52 rods, leaning towards keeping the m52 ones and trading the forged ones towards flywheels / itb fund etc.

Lightweight/lightened flywheel is a much more effective way to rev quicker. The stock one can be safely lightened to ~13lbs which I found was great for mountain driving on my old car. ITB's will yield way more power, but then you need management as well.

As for rods. 84mm stroke gives piston acceleration forces of over 6000 G's at 6,800rpm. Using this, a stock M20 rod @ 626 grams weighs 585 kilograms/1289 pounds more than the IE Tuscan rods at 529g. Lighter rods also impart less side-load onto the pistons, translating to less skirt and bore wear. Then there's the crank weight balancing to accompany that.

As for HP gains it's minimal, but it's there. The higher you rev, the more it becomes apparent. If there was no gain to be had OEM rods would be thicker and indestructible, Metric Mechanic wouldn't be selling 138mm lightweight stroker rods, and titanium and aluminum rod options wouldn't exist. I'm using them for engine longevity more than anything.

Here's a thread exploring it http://www.k20a.org/forum/showthread.php?t=23527&page=2