Engine ideas?

[Guest zfan]

Im looking at building a new short block or purchasing one. Question? Im currently running a 350 edlebrock rpm total package on a 355 sbc. I would like to build another shortblock but go full roller assembley. Have been told to go forged lower end becouse of the high wind capabilities of a roller. Others tell me no its no big deal a stock crank with forged pistons will handle it with no problem. Any opinions out there? Anyone else go this route? Do not think I want to go 383 because of tork and the added stress it brings to play in a somewhat weak 240z.

No twisting pretzles!!

 

Thanks Mike

[Guest Anonymous]

In my opinion, the forged bottom end would just give you a bit more insurance if you decide to spray it, or it gets over-reved. The cast crank with a 4 bolt main, or 2 bolt modified using a 4 bolt splayed cap (even better) will probably hold up ok provided it isn't turned down to far. I havn't seen the specs on the edelbrock system for the 350, but assume its redline is what like 6500? While roller valvetrains do rev easier and have less friction (which is really where they get superiour horsepower not to mention the cam profile), it can also float because of the weight of the rollers.

I guess it comes down to what usage the engine will see and where it spends most of its time running (as well as how deep your pockets are ). Good luck with it.

 

Regards,

 

Lone

 

[ May 26, 2001: Message edited by: lonehdrider ]

[Mikelly]

I've posted here before about this exact subject. My motor builder took money out of his own pocket to set me straight on this issue. You truly don't need a forged crank (Or pistons for that matter) unless you plan to hit high RPMS for sustained periods with high compression or forced induction/ spray. A good cast crank setup as Lone mentioned above (4 bolt or splayed caps) will live happily. I have a hydraulic roller setup and it does rev increadibly fast, but my power plant seems to be fine.

 

ZFan, Check with Michael Jackson...That is one hell of a nice shortblock he is selling...

Mike

 

[ May 27, 2001: Message edited by: Mikelly ]

[BLKMGK]

First of all, 4bolt mains are probably NOT needed, the factory 4bolts supposedly aren't that strong. Depending on usage neither is forged rods etc. The new PM rods are supposed to be stronger than the "Pink" rods of old - consider those as they're CHEAP.

 

Having said that... I went forged everything! I also went 383 and if I did it again I'd go 406 probably. That being said I've yet to drive the car so maybe not

 

I went forged because I wanted insurance. No worries later on about what I should've, could've, would've done. Eagle rods, Eagle crank, ARP everywhere - I used a reputable race engine builder. I can supercharge this sucker, spray it, do whatever I want.

 

I also went flat tappet and perhaps should've gone roller. My reason for that was that the HP range I wanted could be hit without the added expense of a roller, did the same in my Mustang motor BTW. To say that rollers rev fast is fine but do the test back to back with a flat tappet cam, I'm not sure you'd notice a difference in the real world. There's certainly a difference in cam profile but if you're worried about bending the car what HP range are you shooting for anyway? You can hit 425+ HP with a flat tappet cam (shrug).

 

I'd suggest you look at MJ's short block and at the ZZ4 short block. I'm not crazy about the ZZ4's pistons but it sounds like you don't want a ton of HP anyway so.... Jeg's has that sucker intheir catalog now I believe..

[Guest Anonymous]

Just remember any thing can break and everything has its limit, the biggest concern with any spark ignition engine is spark knock, that your worst enemy. Avoid it and your engine bottom end will live a long time. I can't thing of any situation where you would need to turn it harder than 6500 rpm. Jack

[Guest Night_rider_383]

Heres my take on the whole forged deal. I have had alot of folks ask about forged pistons and cranks in my 2 years of running a race engine shop.

 

1st off stock 2 bolt main, cast rods, crank, and pistons are good to about 5500 rpm with mild hp under 400.

 

Same cast bottom end but 4 bolt caps is good to 5800-6000 rpm under 425 hp

 

Now im not saying that the cast bottom end won't stand up to more rpm and power cause it can and will but not safe and not many times.

 

After 6000 rpm look into a cheaper forged crank, rods, pistons,stock 4 bolt caps.

 

For an engine that will see 6500-6800 rpm you can use something like summit stage II rods, trw/speed-pro pistons, and find a parthouse forged crank for under 500 buck. This will live up to 550-600 hp w/o boost

 

After 6800 rpm and 600 hp the game is 100% diff. top brand rods, je, ross etc pistons, at the very least scat 4340 crank. flie fit race rings, arp main studs, arp rod bolts, etc.

 

To tell you the truth its not as the bottom end as the top that keeps you from high rpm's. Valve float 8-10 times kills an engine before a throwed rod, broke ring land, spun bearing, etc.

 

The cam deal well in a street engine they are really about the same, soild, hyd, hyd. roller, soild roller. Its just in the cam profile not the type for a streeter. Now on a race type engine youll see the diff in cam types. With the most power and rpm's going to a high lift, high dur. soild roller with light weight race roller lifters and a rev kit, but to me i don't see any reason to spend 1,800 bucks on a cam set up for a streeter when 95% of the time you won't be using the cam to its max. These cams see the most power in the upper 6,000k- mid 7000 rpm range with some even higher in the rpm band

[pparaska]

I've been bench racing, reading, and participating in the V8 performance scene for 25 years and everything that Night_rider_383 said above rings true.

 

What I don't understand is people putting tons of money into a total engine package (including EFI, etc.) and "saving" a few hundred dollars by going with cast pistons. For a few hundred dollars (if that) over cast or hyper pistons, you can get the excellent detonation resistance with a forged set. This is the beauty of the American V8 engine - the hi-po parts are not much more than stock replacements. Try THAT on an L6! I say buy those forged pistons for the detonation insurance they buy you - you never know when you might get a NOS system cheap! I understand that if you buy a cheap crate motor you don't have this choice, but if you're having it built or building it yourself, why not spend a few more dollars on forged pistons?

 

I also agree on the cam type issue. For the under 500hp street motor, I don't think you gain much from roller lifters - especially if they're the heavy designs some of the companys have for hydraulic roller lifters. The flat tappet cam grinds available today give you all but maybe 1-3% of the torque under the curve that's what needed on the street. Sure, that roller setup saves a bit of horsepower, and might have a smidge more torque here or there in the entire rpm range of the engine, but most engines aren't tuned well enough to find that torque anyway.

 

Just my opinions,