Turbo Engine Planning. 400, 406, 415, or 420. Discuss

[Scott Liggett]

I have been surfing through the parts we use to build engines in order build a new engine for my '65 Impala. To start with, I am planning to build on BluePrint Engine's new small block castings which aren't quite ready yet. Standard bore 400, 4.125 easily bored out to 4.155. That is with 3.75" stroke. The block will have 350 sized mains and 1 piece rear main seal. We have access to 4340 forged cranks in 3.75" to 4.00" stroke.

Second, I will be using BluePrint's 220cc heads. Unfortunately they only come in 64 cc chambers. Makes piston selection tougher.

I want to build something different. 4.125 bore, 3.875" stroke, but to keep compression down to 9.25:1 for turbo boost. That means somewhere around 30 cc dished pistons. Yikes! I have a lot more piston choices is I go 3.75" stroke with 6.00 " H beam rods.

Looking into opening up the combustion chambers a bit, if it's possible without screwing up the chambers.

I am planning on using a nitrous cam from Comp. We use a couple of different ones with .520 to .577 lift. 236 to 248 duration.


The turbos I have are a pair of T70's bought from DNA Motoring. They claim they are capable of 600 hp each. So, I will expect 300 hp each. Believe or not, they are nice quality. I also have turbo manifolds, waste gates, blow off valve, and carb hat. They are set up for 7 lbs of boost, maybe go up to 9 with the boost controllers I also have. I am not looking to make huge boost.

My goal is 700 hp at the crank. Will make my car real fun to drive and still be drivable

[OldMachinist]

I would build the engine to run on pump gas with no need for water or alcohol injection so I would keep the compression between 8.00 and 8.50:1. I know this negates the use of your Blueprint heads and I understand the major difference in cost but you definitely don't want too much compression and I believe the closer you can get to flattop pistons the better. 70 to 76cc heads sound a lot better to me.

I don't think you can open the Blueprint chambers enough to get where you need to go.

Are any of those cranks available with 2.00 in rods? I think any stroker crank for a small block over 3.75 should have 2.00 in. rods for clearance on the cam and block but only the expensive ones seem to come that way.

[SuperBuickGuy]

I'd run away from any bore larger than 4.00 for turbo on a SBC. You just can't get enough area to clamp between the cylinders to keep head gaskets in the motor.

Are they siamesed cylinders? I hate to be the "just no" person, but seriously, there's way too much heat where the head/cylinders meet at the walls and not enough cooling to make it survive on any power level with boost.... in short, you'll have a 500 hp 400 sbc - but you'll say "but I can build that without a turbo" and I would say "exactly"

With that said, I'd love to see a BBC that starts with a 396 block and a 454 or longer stroke crank.... it'd have torque for days, and would rev to the moon... all for dirt cheap since no one wants 396 blocks anymore. Throw on some aluminum heads from the parts catalog - something that flows in the 300 cfm range, a ford diesel turbo.... not that I've given this any thought at all.

Anyway, you asked for my I have pictures of what happens to a 4.185 bore block at 7 psi boost

[SuperBuickGuy]

so a 396, with a long stroke crank and turbo(s) in your Impala... with a 2.0 rear gear and direct drive you'd have amazing fuel economy and your next tech question would be how to get proper aero at 250 mph in an Impala

[Scott Liggett]

No bbc in the impala. They handle like shit. The Caprice is proof of that. Same chassis under both.

[SuperBuickGuy]

aluminum heads would go a long ways towards equalizing that issue.

[squirrel]

I kind of doubt the "long stroke" 427 big block could be built dirt cheap, since it requires custom pistons...while normal 427 pistons, forged, are only $300 a set.

My take on the turbo small block thing....which kind of reinforces a few of the other opinions, in a way...is to just build a 350, and let the turbos to the work. There are a bunch of cheap parts combos you can use to build a 350.

But then, I'm a cheapskate, and I don't have to promote a specific product.

[Beagle]

I... That means somewhere around 30 cc dished pistons. Yikes! I have a lot more piston choices is I go 3.75" stroke with 6.00 " H beam rods.

...

pretty common to see dishes that size in Ford land... 408's and 393's need a lot of dish with a small chamber head like is what most companies offer in SBF (60cc is pretty common). A Probe 14890 is close but has damn little compression height! No way to keep the pin out of the rings, which is something I would worry about with a turbo mill. Honestly, any mill.. oil control could be a problem. Maybe a 377? Turbo'd mill will make a ton of torque, and you'd think that big bore / short stroke should like to rev!

[Scott Liggett]

Anyway, you asked for my I have pictures of what happens to a 4.185 bore block at 7 psi boost

Taking a stock 400 block out .060 over is asking for trouble naturally aspirated. I will be using BluePrint block casting and going no farther than 4.155. But will most likely stay standard at 4.125 to keep compression down.

http://www.summitracing.com/parts/mll-bpsb4125100s

[SuperBuickGuy]

not to argue with you, but to make sure I was clear. The bore wasn't the problem, the sharing of cylinder walls was the problem because where they join they get too hot.

As I said, I don't know anything about the block you're going to use - if it doesn't share a common wall, then all should be good (at least on the cooling front)

[squirrel]

The joining of cylinder walls is a result of the bore being too large. So it's all the same problem, really...and going to a 4" bore fixes the problem.

[Barry Donovan]

not to argue with you, but to make sure I was clear. The bore wasn't the problem, the sharing of cylinder walls was the problem because where they join they get too hot.

As I said, I don't know anything about the block you're going to use - if it doesn't share a common wall, then all should be good (at least on the cooling front)

+1

and the 396 idea, that is a dream.
Enough quiet time can hear what goes by in the woods.
non-siamese is godly...wimpy build or not.
Even a subaru is full wobbling the weirdo turbo cams...
non siamese, go from there.

[Beagle]

anybody wanna touch on long rods in a boosted application?

[Scott Liggett]

The joining of cylinder walls is a result of the bore being too large. So it's all the same problem, really...and going to a 4" bore fixes the problem.

Seeing how nearly all aftermarket blocks for larger cubic inch have siamese bores, including thousands we have built, I think your argument is invalid.

[squirrel]

It's SBGs argument.

How many of your big bore small blocks get turbocharged?