My brother is trying to set up a plan for a roots blown 351W for his 65 ranchero. Since neither one of us is familiar with forced induction, and I am a Pontiac guy through and through, I figured I would throw it out here for some advice on his build up. This will be mostly street driven, daily driver, so it needs to be able to handle pump gas. So, on with the questions. 1. Would you recommend using the 351 longblock, or picking up a 390 for this particular application? 2. Do Ford engines come from the factory with forged rods and crank? 3. If not, with a roots style blower, will he need to pick up a forged crank? 4. What kind of CR should we be aiming for? 5. What kind of headwork would you suggest? Bowl clean up, blending work, or all out porting? 6.We arent looking for a ton of boost, and I know that there is some sort of guide to go by based on cubic inches for supercharger size, suggestions? 7. What type of Transmission will stand up to this engine? The Ranchero is an auto, and unfortunately, I think its going to stay that way. At least for now, until we can locate some parts for a conversion. One step at a time... Thanks for looking, and if you need anymore information, feel free to let me know. Also, if you think there are other things we should be looking for with this plan, let me know. Again, I have very limited knowledge when it comes to forced induction. Thanks for the help, Travis
Some basic answers about the Ford engines. I'm not experienced with supercharging either so I'll just try and help with basics. 1.) The 351W and 390 are completely different engine families. Since he's planning the 351 I'll stick to that context. 2.) For the most part Ford engines come with cast cranks and sturdy forged connecting rods BUT have no fear the cast cranks are very sturdy. Ford pioneered cast crank metalurgy and all of them are high quality nodular iron. Further there is generous overlap between the main and rod journal diameters. These factory parts should hold fine to 600hp at reasonable rpms. Forged pistons designed for supercharged applications would be a good idea. 3.) No not with street power levels. 4.) I defer to the forced induction experts 5.) Fords are weaker in the exhaust port area. Concentrate there. 6.) see answer 4 7.) A good C6 will hold it fine as well a carefully built C4. Blue Thunder has the blower manifold for this application: http://www.bluethunderauto.com/id22.html As with the Jimmy blown small block Ford pictured you're gonna have to either use a tall intake or an alternative dist drive
A lot of this depends on exactly what your brother wants/expects. If the main purpose of this is visual, with occasional showy burnouts & 1/2 block blasts (I don't mean this in a bad way, that's what most blower engines are built for... ), the existing 351 shortblock would be fine, cast pistons & all, along with some mild port work. Blend the bowls & transitions, blend/reduce the guide bosses, deal with the Thermactor bosses, if any, & you're done. If you are willing to go a bit farther, detail-wise, then I would pay some effort towards getting the deck height equalized & set correctly, even with the cast pistons. The compression ratio will be fine as is for 93 octane. Many of the blower builders would suggest to you, given those build circumstances, that you run somewhere around 8-10% underdrive. I won't say "boost"....that's something of a misleading term with a Roots-type blower. If you are willing to go farther with things, (or expect more out of it), I would look at forged pistons. I am not a fan of the common TRW/Speed-Pro stuff offered now as of 2007...used to be good, but times have changed....Diamond, JE, & others make specific blower pistons, for whatever head/chamber design you have, & they're worth the extra money. That's a tough call...you'll need to ask yourself serious questions about how the engine will be used. Along those same lines, there are any number of aftermarket heads that will far outperform any factory 351W head...just depends on the budget. Compression-wise....most blower engine builders suggest keeping the compression lower, like 7.0-7.5:1 on serious pump-gas engines, & making the power back with more drive ratio & cylinder head capability. As Henry said, the Ford cast cranks & 351W blocks are amazingly tough & will outlast almost anything, as long as attention is paid to clearances & machine work. The 351W rods are good too; you may find that it is more cost effective to use basic Scat/Eagle/etc. rods rather than do the machine work on the stockers. I'd talk to a cam grinder about specific profiles, but if you look yourself, keep the overlap to a reasonable minimum...in other words, a fairly mild cam, & let the blower do the work of filling the cylinders, not the cam. Use a good ignition...not ProComp crap....& pay some attention to the cooling system. One mistake commonly made on Fords is to install the head gaskets incorrectly, which causes severe overheating....thought I'd mention that since you're a Pontiac guy. The C6 is incredibly stout & will hold up well pretty much as is. SBF C6s can be harder to find; 351W Econoline vans from the '80s are one source, although the tailhousing may or may be correct. SBF Mustang C6s are fine but usually have a higher price tag. 351W powered intermediates & full-size cars are a good source. The C4, as Henry noted, will need some work to survive here. However, they will probably be a lot easier to jam into a Ranchero trans tunnel. A '65 would have had a C4, originally.
If you're not after a ton of boost, and are looking to get something together without too much fabbing, maybe start with a Weiand kit for a 302 like this: http://www.holley.com/types/Small Block Ford - 174 Series.asp It's for a 302, but there are intake spacers available for 302 intakes to fit on a 351W. Then you'll already have a blower with an offset drive snout to clear the distributor. As mentioned, the exhaust ports are crap, so do lots of work there, or consider picking up a pair of aftermarket heads if they're in the budget. I remember seeing a dyno test many moons ago on a 302 with a B&M blower that picked up a ton of power with aftermarket heads vs. stockers, just because the extra air had somewhere to go. cheers Ed N.
Thank you guys so much for your input! Tons of useful information to point me in the right direction. Im sure I will have plenty of questions as we go along, but thanks again for taking the time to help. Travis
"2.) For the most part Ford engines come with cast cranks and sturdy forged connecting rods BUT have no fear the cast cranks are very sturdy. Ford pioneered cast crank metalurgy and all of them are high quality nodular iron. Further there is generous overlap between the main and rod journal diameters. These factory parts should hold fine to 600hp at reasonable rpms. Forged pistons designed for supercharged applications would be a good idea." I want to revise this because it does'nt say exactly what I mean. I would'nt have any problem using the stock block and crank to 600hp. The factory rods (with good fasteners) would probably sign off at around 500hp in most apps. At the 600 hp level I would invest in a decent set of H- beam rods. These are very cost effective at this time.
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