kc8oye Posted February 17, 2007 Share Posted February 17, 2007 I guess this is kinda directed at Rice... but I'm open to anyone's opinions!!! I think I'm gonna just build a whole new engine instead trying to do a cam-swap 'in-car'... I'm pretty set on the top end.. CompCams XE-268, Edelbrock Performer RPM (NOT air-gap) I was going to use Edelbrock Performer RPM heads.. or Holley SysteMax.. but after reading that sticky post of Rice's on the L31 vortec heads.. I dunno.. but what I'm wondering.. is how far (read expensive) I need to go to ensure the bottom will remain sound? I'm expecting 420-ish hp, 450-ish torque.. and good power out to about 6000 rpm.. lets say 6500 for safety.. will a 'stock' cast bottom end support this? I'm going to be using a 350 chevy truck 4-bolt block bored .030.. I was also wondering if it would be worth the money at this power level to consider having the factory 4-bolts re-machined as splayed 4-bolts? Should I consider a high-volume oil pump? I'm wondering if it's really needed on a brand new engine? let me know what you guys think.. thanks Link to comment Share on other sites More sharing options...
Guest Posted February 20, 2007 Share Posted February 20, 2007 You don't spay 4 bolt blocks. Only 2 bolt blocks get splayed cap put on them. The two outer factory bolt holes combined with the new splayed hole seriously weaken the main web. A two bolt with studs will be plenty strong for the power level you seek! Save the bucks and run the l31 vortec's with the rpm airgap it will make the power you seek for less money! I have a test car with the 906 casting voretcs, rpm air gap, 750DP hp style(proform), MSD ign, hyd roller(my design), 6" scat rods,ross forged flat top 2VR pistons that makes 500 hp and 490 ftlbs all under 6000 rpms on pump gas! It was built for NOS, 200+ shot. The only mods to the heads are good valves,springs,retainers and screw in studs. No guide plates running the guided rockers. It still works the power brakes(barely) and still has A/C on it. It's not for everone, it is a little ill mannered but still streetable. You can not run it with a one legged rear end and get on it much! It has left a one leg black mark for 1 mile+ already!!! Gas milage? NO! Does the exh sound bother the neighbors? YES! For a 350 pump gas engine it screams! unless you are going to go bigger later the vortec's will be fine! Don Link to comment Share on other sites More sharing options...
kc8oye Posted February 20, 2007 Author Share Posted February 20, 2007 Thanks for the info Don... what about the bttom end tho? all o.e-spec cast components ok? my main question is pistons... will hyper's survive some nitrous? also... one of the guys on here.. is running the XE272 cam... do you think this cam would still make for a good street-driver cam with the vortec's? and maybe make a lil' more power? one last note.. on teh intake.. I specified NON-airgap because I've been warned by a few people that the air-gap manifolds don't work well in cold air. Link to comment Share on other sites More sharing options...
Guest Posted February 20, 2007 Share Posted February 20, 2007 No to the NOS on hyperutectic pistons period! Take some words of wisdom from Jackie Geason in Smokey and the Bandit here! "You can think about it BUT DON"T DO IT!" The Hyper pistons are actually very brittle and the shock load from the instant in crease in cly pressure breaks the ring lands down! I know if you call KB they say yes it is safe to run NOS on our hyper pistons. It's Bullsquirt!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! I've never seen on on a dyno even with a fat fuel jet survive more than a few pulls till the power falls and it begins to blow smoke out the crank case breather and the exhaust. If pushed after that point they all grenaded. If you then call KB and tell them your new engine went kaboom and send them a failed piston they will say improper clearence,improper ring gap,improper tune up or anything but a piston failure even though it's evident. Hyper pistons are for street cruisers without power adders and must be tuned so it can not spark knock at all period. Setup and run this way they give a great service life even if you strecth her out once in awhile. The xe268 cam will give you better all around performance for a daily driver and nearly the same peak power with better low end. Use an electric choke carb and the airgap is not a problem. Don Link to comment Share on other sites More sharing options...
680HPStroker Posted February 20, 2007 Share Posted February 20, 2007 Unless I missed something you guys never addressed the crankshaft itself. I know that for a street car a new cast crank with either 4-bolt mains, or two bolts with studs will more than likely never have any issues no matter how much you thrash it, but I like leaving nothing to chance. For my money if I'm already buying forged rods and forged pistons why not get a forged crank and make the whole rotating assembly practically bullet proof. I'd have the rotating assembly balanced to within + - one gram and do this with a good quality SFI approved harmonic balancer. It may sound like over kill, but many have had failures in the past from building an engine for where they want to be for now and then they start squeezing their engine more and more and then kaboom. Just my two cents. Link to comment Share on other sites More sharing options...
kc8oye Posted February 20, 2007 Author Share Posted February 20, 2007 cuz an all-forged bottom end is way beyond my budget right now.. and I need a new engine _now_ .. Link to comment Share on other sites More sharing options...
Guest Posted February 21, 2007 Share Posted February 21, 2007 KC, as long as you DO NOT RUN NOS or over rev(5500rpms) the bottom end will survive quite some time. For the budget go with the vortec's. Put the money saved on heads and put it into the bottom end you will be better off in the long run. Don Link to comment Share on other sites More sharing options...
kc8oye Posted February 21, 2007 Author Share Posted February 21, 2007 I was planning on taking it up to 6k don.. is that maybe pushing it too hard on a stock bottom-end? or am I just being over-hopeful on how far out I'm gonna be making usable power? Link to comment Share on other sites More sharing options...
gprimm Posted February 21, 2007 Share Posted February 21, 2007 Don, don't mean to butt in on the thread, but upon futher consideration, with a son in college I am not going to spend alot on new aftermarket heads right now. Assuming the Vortec's are better than the crate heads on the engine I got (350/290hp) would the Vortec's help and if so, do you have a set? George Link to comment Share on other sites More sharing options...
Guest Posted February 21, 2007 Share Posted February 21, 2007 George, they would be better. The std old style intakes don't work. The best intake for the vortec at this time is the RPM air gap. Would really pep things up even uses the the same guided rockers as on the crate engine now. In stock form the vortecs can only handle about .450" lift. Here is the draw back, by the time you buy the upgraded vortec heads at around $340 a piece plus a 200$+ intake,25$ for intake bolts, new center bolt valve covers any where from $80 to $150+ for nice looking ones. You have more in the vortec's than the dart's which use old style intakes like the 300-36, roller rockers like you have from the old engine. Plus the iron eagles have more potential than the vortec's straight out of the box and can be ported to way more than a vortec can be. You would be a $1000/$1100 for the vortec deal, or the $1200 range for the Darts with the 300-36 intake. Spend the extra for the Dart/300-36 combo it will work way better for about the same money in the end and be a better more durable combo. Don P.S. Don't have any heads that would help you at this time. Link to comment Share on other sites More sharing options...
Guest Posted February 21, 2007 Share Posted February 21, 2007 I was planning on taking it up to 6k don.. is that maybe pushing it too hard on a stock bottom-end? or am I just being over-hopeful on how far out I'm gonna be making useable power? Thats pushing a hyd cam combo close to the normal vlave float range of 6100/6200 rpms. Valve float breaks springs and drops valves which destroy engines! Beside even if it doesn't float you are dropping power at that rpm with that cam. So it's a waste of time to spin it the extra 500 rpms! Don Link to comment Share on other sites More sharing options...
kc8oye Posted February 21, 2007 Author Share Posted February 21, 2007 Thanks for the info Don.. . I think this weekend I'm gonna investigate some local machine shops.. maybe get the crank in to get it posilished and or turned as the case may be.. make sure it is straight yadda yadda... I heard on one of the car shows over the weekend that laying a cast crank on it's side can make it sag from its own weight.. is this true? or is this somthing that would take _YEARS_ to happen? cuz both my spare cranks have been laying on their side for at least a year now.. Link to comment Share on other sites More sharing options...
gprimm Posted February 23, 2007 Share Posted February 23, 2007 Don, Thank you. College is still in the picture for my oldest son for one more year so I was thinking that the Vortec's would be a little cheaper and better. But all that makes sense . . . I'll just have to wait !!! I assume buying the vortec's I could not change the springs from what I have now on my current heads (Comp Cams). George Link to comment Share on other sites More sharing options...
gprimm Posted February 23, 2007 Share Posted February 23, 2007 Don, Thank you. College is still in the picture for my oldest son for one more year so I was thinking that the Vortec's would be a little cheaper and better. But all that makes sense . . . I'll just have to wait !!! I assume buying the vortec's I could not change the springs from what I have now on my current heads (Comp Cams). George Link to comment Share on other sites More sharing options...
kc8oye Posted February 25, 2007 Author Share Posted February 25, 2007 I'm actully kinda shocked at how cheap forged bottom end stuff actully is... I figured I'd be spending $1000 for a crank, and $700 for rods.. etc What do you guys think of the Scat chevy 4340 Forged crank? it's $550 from northern autoparts.. http://www.northernautoparts.com/ProductModelDetail.cfm?ProductModelId=16495 $170 for forged rods.. http://www.northernautoparts.com/ProductModelDetail.cfm?ProductModelId=3023 $235 for forged flat top pistons I think I've got a good recipie here for a very solid bottom end (one that I can throw some nitrous at if I want to) Link to comment Share on other sites More sharing options...
kc8oye Posted February 27, 2007 Author Share Posted February 27, 2007 woo hoo.. bought an edlebrock performer rpm (not airgap) off ebay today.. $106 including shiping.. theyre $142 at the local parts store.. and $135 from summit racing.. so I guess i did ok.. only problem is it's a square bore type.. .guess I'll ahve to get me a qjet-squarebore adpater Link to comment Share on other sites More sharing options...
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