DTMR

I want to do the FRPP heads as my next power mod to my motor, either the big valve ones or the stage 1 heads. I just want to know that my motors going to be safe because I hear of horror stories of people blowing up the bottom end. I know thats when you make over 550 rwhp but I plan to do a little racing with it and I just want to know the motor can handle it. Stupid rods

moosestang

I can not think of a single post in the past 7 years of a naturally aspirated 4.6L 3v loosing a cylinder. There are more 5.0's dropping like flies in the first 2 years than all 5 years of the 4.6 combined. I'd bet money on that.

I don't remember seeing any spun bearings either. The rods seem to break before the pistons or anything else. Just keep the rev limited at a sane rpm and you'll be fine. Trying to spin it to 7k is probably a bad idea. I wouldn't go past 6500 personally. That's as high as any aftermarket tuners would set it.

808muscle

Me too, never have read about a N/A blown motor. Boost with a bad tune is the wrong combo. Make sure you talk with a tuner before you do those mods.

jpplaw

I have a B326 longblock in the process of being built by Brenspeed. I asked about using the FRPP big valve heads. Brent said that while the larger bore may take advantage of the bigger valves, the size of the cam would be the limiting factor. Because I am using the DR cams, with a .450 lift, the heads would be overkill. To take advantage of those heads you should use cams with a lift over .550. So I went with FRPP stage 1 with upgraded springs instead because I would rather keep my drivability factor high and keep the DR's. I imagine Hot Rods are pretty much the same, lift-wise.

The only N/A motors I have ever heard of being trashed were either caused by bad maintainance, bad tune (lean at WOT for an extended period), or over-revved (rev limit changed in the tune). The stock rods really are crap.

moosestang

What's the final cost of that?

jpplaw

Without extra's, its around $8900, uninstalled, with FRPP mounts (needed), and FRPP stage 1 heads with comp cams springs & retainers.

jpplaw

The B326 is about 60lbs heavier but I will have my original aluminum block motor gathering dust in the corner of my garage in a couple months....could be persuaded to let it go for a reasonable offer.....would great for a DIY build

def67

^^ So you didnt blow your motor just upgrading?

jpplaw

Yep, just upgrading to have a forged bottom end so I can turn up the boost a bit. There is about 80k miles on the stock bottom now, so I figure its better to be safe than sorry.
Brent is going to dynotune the new motor, so it will be a safe reliable beast!!

moosestang

That's not bad at all.