Im going to be converting my 1994 Chevy truck over to TPI soon and Im trying to decide on whether to build a 406 TPI or just stick with building a 383.... I know that 383s can be expensive to build up the torque but the 400s start off with alot more. I havent heard much about people using a TPI setup on 400s but is it more reasonable power wise or is it too much trouble because of knock sensors and electronics?

 

I am in the same building process. I actually have a 355 with a superram intake, and I really need more torque out there. Another member: Brutalform (if I clearly remember) has been threw this process. So maybe verified for his past posts and/or ask him for good advice from his personnal experience...

Are you gona stick with the stock tpi unit?

 

TPI 400's, been there, done that, seen plenty more since I got my IROC way back in 89 around the time I just got my driver's license.

Ran a 406 (400 with .030" over bore) for years. Never had an issues with cooling that wasn't there with the 383 or the 350 before it. Nothing really exotic or off the wall with the 400's. It all really comes down to finding a good core unless you're going aftermarket block. Max limit you want to go on the bore is .030". Anything more makes the cylinders a little on the thin side. At that point you'll want to get the block sonic tested to make sure there's enough material between the siamesed cylinders. Only thing the 400's need are the steam holes for the cylinder heads for cooling purposes. Deck plugs will help keep the deck from cracking. Everything else I had on the original 350 worked. Scrap the stock 400's crappy 5.56" inch rods. Too much angular force against the cylinders and you'll get more rotational torque from the longer rods. You'll want to get pistons that use the 350's 5.7" rods or longer aftermarket rods.

I really don't know what you mean about 383's being real expensive to build up the torque. First 383 I built with a stock cast 400 crank with the mains turned down had tons of torque. Was able to build the short block for about $1k including parts and machining. The stroke is the same except the bore (4.030" vs 4.125" of a non bored out 400, bored out would be 4.155). There are so many 383 crank kits and parts out there now that building one costs as much as rebuilding a 350.

383 with a late model roller block keeps the cost down on running a roller cam. You won't need retrofit lifters (stock roller lifters are about $200-$300 less) and the anti-walk plate is there so you won't need funky cam buttons and reinforced timing covers or having to weld in hardened steel shims under a stock timing cover.

Personally if I didn't have an extra 400 block that hasn't been bored out yet, I'd just build another 383 cuz it's so cheap to build. Build off a good a late model roller block with the 1 piece rear main seal so you don't have to deal with the crappy 2 piece deals. Definitely get the block checked though as late model roller blocks are notorious for cracking at the lifter valley. Never had that happen to me with the many 383's I've built but I did run into a core a buddy gave me that had a good 5" crack in the lifter valley. You can slap in that nice roller cam for cheaper and throw the extra cash at some nice flowing heads and you're good to go. Unless of course you go flat tappet, but why would you want to do that? =)

Build the 400 only if you want the bragging rights of more cubic inches or if you want to build a high winding 377 (400 block with 350 crank) and want to rev past 6500RPM. Those 377's are pretty damn nice screaming up to 7000RPM with a TPIS Miniram.

383 or 400, you'll want that thing to breath. The stock TPI intake won't cut it unless you want some stump pulling low RPM motor.

Just my 2 cents...

 

Well If I stick with the TPI setup, is everything else going to be able to handle a 406? I mean is it even tuneable? I know ill have to have huge injectors and im definately going with a 58mm TB but I already have SLP siamese runners and a ported intake and plenum to match. Im probably going with come Procomp Aluminum heads that I came across. Alot of people dont give these people much credit but I read a build in a super chevy magazine about a 355,383,&,396 they built and the 383 was amazing with those heads. Where would I even begin with injectors? about 42lb/hr???

 

You can put any intake on a 406. You will just limit the amount of power you make depending on the intake you choose. I did one with ASM large tube runners and ported base. Was better when I slapped on a ported Edelbrock. I ran Ford Motor Sports 24lb injectors with 42psi of pressure with that setup. It's all about the tune. No you won't need huge injectors. 42lb injectors would be over kill since the flow of the TPI will be the limiting factor. My current 406 with TPIS Miniram is with 30lb injectors. What exactly will you be doing with the truck you intend to put this motor in? Daily driver, towing, street/strip?

 

Well this setup is going in my 1994 z-71 truck and its my daily driver. I want something thats strong and dependable but I still want that stump pulling torque...... I dont like anything close to stock and everybody runs a 383. I gotta try somethign different.

 

I always did like the 400's. Then again...I'm biased like that. Make sure the you use a virgin block that hasn't been bored over. You don't want to go over .030" over bore or the cylinders run thin. Unless you plan on getting a new block like the Dart Little M or World Products Motown block.

Make sure the steam holes are there. Some of the later 400 blocks didn't have them, I've run into 2 of those. If you don't run the steam holes, you're going to run into cooling issues. You'll have to have your heads drilled for the steam holes as well. The lower 3 holes on the exhaust side of the block will be the important ones to have. The upper 3 near the intake/lifter valley side of the block aren't necessary.

I also prefer the 2 bolt main blocks and have my machinist convert them to 4 bolt splayed main caps. For your application, a factory 4 bolt main block is fine.

Cam and heads you're going to have to match up to the TPI setup you plan on going with whether you're leaving the TPI stock or are going ported base/large runners, aftermarket base/large runners etc.

Another motor out of the norm would be a 396 small block. Something to consider?

Good luck with the motor.

 

if its going into your daily driver id say go with the 400 just because it will keep about the same RPM range as you currently have.

theres no need to rev past 4k, and your truck will have rediculous amounts of lowend torque... you could drag someones car across a parkinglot no problem

 

You could even have a 400+ ci motor built from a stock 350. You could turn it from a 350 to a 408 by boring it .40 over and adding a 4.00 inch crankshaft. Of course You would need the block machined for the bigger crank. But at least You wouldn't have to worry about the possibility of overheating and drilling steam holes in the cylinder heads. A mild 406 or 408 with a slightly modified long tube runner set up should have no problem making at least 500 lb ft. of torque. Google T@L engine development. They have some nice looking and affordable stroker engines for sale.

 

the dragging cars across parking lots is a good idea..... theres a few people I dont like. lol but the 400 would also be cheaper because I would have to dump quite a bit into a 383 to get NEAR the torque a mild 400 will produce. I think thats what im gonna do because conveting my truck from TBI to TPI is no biggie and I have a complete 91' TPI top end I picked up for $150 I just gotta sell my LT1 i was building and start on my 400. I already have a virgin block thats ready to start building!!