N/A aftermarket rods?

[mr2peak]

Doesn't anyone make a set of rods for a natural aspirated M20? All I can find are 500g+ H Beams made for boost. S52's are 535g. Anything in the 450g range without shelling out for custom rods?

I found titanium Pauter rods for ~$6090 a set.. that's not happening.

[digger]

Molnar H-beams are just under 500g and great for clearances for the big cranks. cheap and good quality for the $$$.

MM can sell ultra light I-beams but are 138mm and 21mm pin and like $1200 475g iirc

pauter can do ultra light NA version of the rods but too much $$$

to be honest i wouldnt worry too much about the mass, even OEM m50/s50 style rods are perfectly fine for lots of revs just get good bolts

[varg]

No point unless it's a really high strung and heavily worked engine. You won't make enough power to hurt the stock ones, and there's no point in revving high enough for them to be a liability unless you're really going all out with a high dollar high compression cammed out build that will actually make more power beyond 7k.

Video related

And this build used M52B28 rods.

[SkiFree]

As you mention the 135mm S52 rods are 100grams lighter each vs the factory rods. The ebay/eagle/sp/ie rods are a bit lighter still as you mention, but I would stress that you'd still want to match them and them sized.

As you have found there isn't a cost effective step beyond the point you are at.

[SkiFree]

As you mention the 135mm S52 rods are 100grams lighter each vs the factory rods. The ebay/eagle/sp/ie rods are a bit lighter still as you mention, but I would stress that you'd still want to match them and them sized.

As you have found there isn't a cost effective step beyond the point you are at.

[mr2peak]

Molnar H-beams are just under 500g and great for clearances for the big cranks. cheap and good quality for the $$$.

MM can sell ultra light I-beams but are 138mm and 21mm pin and like $1200 475g iirc

pauter can do ultra light NA version of the rods but too much $$$

to be honest i wouldnt worry too much about the mass, even OEM m50/s50 style rods are perfectly fine for lots of revs just get good bolts

I was looking at Molnars, as well as Arrow and Eagle. They all seem basically the same, IE as well. I was even thinking of getting 2 sets of Cxracing rods, using the best 6, and returning the rest.

Rods have to be 135mm as I already have the Mahle/IE 2.9 pistons, so I can't cross-shop other lengths.

Revs won't be very high. I'm looking at rods because S52 rods will need to be purchased and inspected, and possibly cleaned up as well. Might as well spend that on new rods that weigh less.

[digger]

I was looking at Molnars, as well as Arrow and Eagle. They all seem basically the same, IE as well. I was even thinking of getting 2 sets of Cxracing rods, using the best 6, and returning the rest.

Rods have to be 135mm as I already have the Mahle/IE 2.9 pistons, so I can't cross-shop other lengths.

Revs won't be very high. I'm looking at rods because S52 rods will need to be purchased and inspected, and possibly cleaned up as well. Might as well spend that on new rods that weigh less.

Molnar are sized properly from what ive seen where as eagle/CX and other ultra cheap ones not so much. Arrow are extremely expensive and sounds like a total waste for your application. you're better of spending money on things that matter alot more.


the other ones ive seen that look good are the I-beam from integrated engineering

http://www.performancebyie.com/integrated-engineering-tuscan-135x22-rods-bmw-m50-m52-s50-s52

[TobyB]

Revs won't be very high.

then you should be ok with almost anything.
Rods just don't fail in compression.
It's the off- throttle at 8250 that pulls the caps off them...

There are some gains to be had in rods, but they're tiny- BMW knew their shit
when they made these engines...

t

[varg]

^finally someone else here is picking up what I'm putting down.

[mr2peak]

^finally someone else here is picking up what I'm putting down.

Oh no, I get it. I know I won't be getting a bunch of HP from rods, that's not the point. The engine is a 85/84mm 2.9 M20 with the IE/Mahle pistons, ARP studs, mild porting, 272 cam, supertech valves, HD rockers, new springs, retainers and rocker shafts. RHD ITB's, IE long tubes, custom mid pipe to Stromung catback with MS2 to tune. 323i flywheel to keep it nice and street-able. Rev limit at 7,500 but I doubt it will make power that high up. I would like to use the nitrous controller to run a 2 stage 50/50 shot to get ~300 to the wheels for the drags. Admittedly 300whp easily handled by any of the rods available.

But this is not a "budget" build, nor a "race" build. It's a middle-ground street build with longevity in mind. Stock rods lack rifle drilling; adding oil squirters to make up for this is not always the best thing, and will cost more money. Used S52 rods might have to be re-machined to fit. Again, that will cost more. Might as well use the money to get something better to begin with; a few hundred more spent wisely won't ruin this project.


I sent an email to Integrated Engineering, they seem like a great middle-ground between the budget options and the "more than I want to spend" collection.

Molnar's seem to be the lightest option within budget. No rifling but that's not a deal-breaker, most M20 rods do fine without.

Arrow are extremely expensive and sounds like a total waste for your application.

Way above and beyond my comfort level. Seems that I was looking at single rod prices, not the set of 6.

[TobyB]

Nitrous is not, in my book, n/a anymore.
So yeah, maybe you need more, since 7500
seems to be the outer limit for stock rods.
I'd say with 50 you'd probably still be ok,
but saying 'I'll keep it to 50'
is like saying 'I'll only ever go to 1/2 bar' with a turbo...

t

[mr2peak]

I will keep it low. I have a very clear goal with this car, and high nitrous is definitely not on the list. Turbo would be a way better choice if this was the case.

Anyone have input on the value of rifle drilling?

[varg]

Nice to have but E30s run endurance races without them and have no trouble...

[digger]

Anyone have input on the value of rifle drilling?

its not required for what you are doing, nothing wrong with it but probably youre paying extra for it...

[ForcedFirebird]

Oh no, I get it. I know I won't be getting a bunch of HP from rods, that's not the point. The engine is a 85/84mm 2.9 M20 with the IE/Mahle pistons, ARP studs, mild porting, 272 cam, supertech valves, HD rockers, new springs, retainers and rocker shafts. RHD ITB's, IE long tubes, custom mid pipe to Stromung catback with MS2 to tune. 323i flywheel to keep it nice and street-able. Rev limit at 7,500 but I doubt it will make power that high up. I would like to use the nitrous controller to run a 2 stage 50/50 shot to get ~300 to the wheels for the drags. Admittedly 300whp easily handled by any of the rods available.

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.