Just how much abuse will stock rods take?

[brent_strong]

This question was prompted by my post over here:

http://www.mye28.com/viewtopic.php?t=24768&highlight=

It seems that I will be sticking with the stock M30 rods, at least for now. I'm just wondering if anyone here has had experience with exploring the limits of what the stock rods will hold for power?

The setup as planned is:
E34 3.5L M30
8.2:1 pistons (same as Pat Philpot runs in his Big Red car)
APR head studs
APR rod bolts? Are they available? Necessary?
Balanced rotating assembly

Thanks for any experience or opinions!

[brent_strong]

Looks like TCD made 440ft/lbs to the wheels on a stock bottom end...I won't be looking to make much more than that, just carry that TQ further out in the RPM range.

[Matt]

I won't be looking to make much more than that, just carry that TQ further out in the RPM range.

do you mean that you'll be trying to move the torque higher in the rev range?

rpm's are harder on engines that boost. the m30 will take 20+ psi at 5000 rpm but probably fly apart at 8000 rpm @ 0psi

[gol10dr1]

there is a e34 m30 in sweden built by pure performance factory that uses stock rods and some forged parts in the motor. the thing made 710hp on an engine dyno at 6500 RPM. i spoke to the guy who built the motor and he said that is probably on the brink of destruction for those rods but i never heard anything about the motor popping so who knows? stock rods have been perfect for me running 480-500ish crank hp and i dont plan on upgrading them.

[brent_strong]

Awesome. That is what I like to hear.

Was that Swede Andreas by chance? I've spoken to him a bit about my project to get some guidance - very cool guy.

As for my previous comment about carrying the torque, yeah, I just would want to shift the tq curve higher in the rpm range to make more hp. 420-450ft/lbs at the wheels at 6500-6800 would meet my original maximum power goals. 350ft/lbs would meet my conservative minimum goals.

gol10dr1, how high do you rev your engine? I'll have megasquirt running my setup, so I'll be free to choose my limiter. I had planned on somewhere between 6500-6800, but I wasn't sure what the engines would be good for.

[gol10dr1]

i never rev my engine over 6400 RPM and i seldom go that high, generally around 6000 RPM if i am going wot on the street. as for the torque numbers........i made 455rwtq at like 5000 RPM so your goal of 450 tq at 6500 RPM probably isn't all that realisitic. these engines make gobs of torque and make it early.

[brent_strong]

Well, what turbo are you using? That should really determine (most) of the torque curve.

Why don't you rev very high? To be completely honest, I don't know what the stock limiter is for the M30 (never had one that was in a car and running), but I'd imagine it should be good for 6500 reliably. I really need to just talk to Pat and see what he's doing to get the job done...

Obviously I don't want to make a screamer out of the engine (had my fill of that with my S2000), but I'd like to carry a nice flat torque curve that remains near peak torque until ~500rpm before redline.

My goal is to make my torque up high. Before 3k, the power of the NA engine should be plenty. After that, the fun should begin.

We shall see....

[T_C_D]

Well, what turbo are you using? That should really determine (most) of the torque curve.

Why don't you rev very high? To be completely honest, I don't know what the stock limiter is for the M30 (never had one that was in a car and running), but I'd imagine it should be good for 6500 reliably. I really need to just talk to Pat and see what he's doing to get the job done...

Obviously I don't want to make a screamer out of the engine (had my fill of that with my S2000), but I'd like to carry a nice flat torque curve that remains near peak torque until ~500rpm before redline.

My goal is to make my torque up high. Before 3k, the power of the NA engine should be plenty. After that, the fun should begin.

We shall see....

There is no secret here. The cam will dictate where the power is made. The bigger the cam the later the torque arrives but the longer it lasts.

I use a 260 cam in my car. I see no reason to go bigger. It's much easier on the engine to use the 3000-6000rpm power band than 4000-7000.

Todd

[brent_strong]

Yeah, I should be able to get the job done by 6k.

I'd still be very interested in what turbo you're running, gol10dr1.

Thanks for the advice and suggestions. The engine should be sent off for the rebuild in the next week or two and then comes the fun of putting it into the E30.

[russc]

There is a thread for Andrews build, search down the threads some.

RussC

[brent_strong]

Found it, thanks.

[gol10dr1]

i currently have a 60-1 turbo but was dead set on going bigger until a bunch of recent set backs. will probably end up going bigger Anyway, just not as big as i had planned before.