Looking for advice on a blueprint engine.

[Johnny Mac]

They list the 400 as 510 lb/ft but the graph doesn't show that

You are correct. This engine was re-rated a few months back, and looks like we never updated the graph!

 

[Johnny Mac]

Both engines are similar in hp/tq, this is going in my 58 Chevy Pickup, this will be hot cruiser with a 350 trans and a 2400 stall converter.

It currently has a 77 Camaro front clip with the donor 350. I think it was a whopping 195hp engine when it started out, but no so much today. The rear gear is a 3:08.

Keep in mind with a 3.08, it may still feel a little doggy... I know a th350 will be a high winder, but may consider a gear change if this is just a street bruiser.

I'd probably take the one with the smaller cam and longer stroke since you're putting it in a pickup with that gear and converter.

I wonder if Johnny could send you the full dyno sheets for each so you can overlay them to compare graphs.

Yep! @Heywodja email me and I can send a real dyno from each one.

 

[lemondana]

Having to add octane booster sucks donkey dicks! Get the one that will run on 91, you won't be sorry.

 

[Heywodja]

Thanks @Johnny Mac who sent the updated dyno sheets!

Johnny explained that the 400 will run on 91 octane all day with no problems, the 396 will not be as accommodating when it comes to the type of fuel, so I am going with the 400. They are within $100.00 of one another on cost.

Anyway..
I am still confused, and I know there is some voodoo in the math which makes these two engines almost identical in HP/TQ.

They both use the same 64cc Blueprint heads. same .041 gaskets, I am not sure of the piston volume or whether the pistons above, flush or below deck height

The 396 has an advertised compression ratio of 10.4:1 with 6.00 rods and a 4.0 bore.
The 400 has an advertised compression ratio of 10.3:1 with 5.70 rods with a 4.125 bore.

The 396 uses this Camshaft:
Hydraulic Roller Cam - .544 Intake / .555 Exhaust Lift and 230 Intake / 236 Exhaust Duration @ .050 - 110° LSA

The 400 uses this camshaft:
Hydraulic Roller Cam - .555 Intake / .576 Exhaust Lift and 236 Intake / 242 Exhaust Duration @ .050 - 110° LSA

In the words of Tommy Boy - You could get a good look at a T-Bone if you stick your head up a bull's ***, but think I'll just take the butcher's word for it!

 

[33IMP]

I don't know what the fuel situation is in Texas, but here in California, 91 loaded with corn squeezins is the BEST you can get anywhere, (short of $12+/gal race gas).
That makes Johnnie Mac's 400 suggestion a no-brainer in my book. I don't want any driver that can't run on straight pump gas available where I'm at.

lemondana tree'd me!

 

[KC69Cuda]

Both engines are similar in hp/tq, this is going in my 58 Chevy Pickup, this will be hot cruiser with a 350 trans and a 2400 stall converter.

It currently has a 77 Camaro front clip with the donor 350. I think it was a whopping 195hp engine when it started out, but no so much today. The rear gear is a 3:08.

Now that you've got the engine decision ironed out, is that TH350 built with any internal upgrades? Questioning if it'll handle that torque. A TH400 would be better suited IMO.

 

[Heywodja]

Now that you've got the engine decision ironed out, is that TH350 built with any internal upgrades? Questioning if it'll handle that torque. A TH400 would be better suited IMO.

I am working on that, I Kinda want to stay with the 350 so it dosen’t have the kick down cable.

 

[273]

Anyway..
I am still confused, and I know there is some voodoo in the math which makes these two engines almost identical in HP/TQ.

Confused that two similar size engines built similar come out with similar power?

People always seem to acknowledge that longer stroke has more multiplying effect, but overlook bigger pistons have more surface area for pressure to be applied, allowing more force to be multiplied.

 

[BrianT]

I am working on that, I Kinda want to stay with the 350 so it dosen’t have the kick down cable.

If you're changing transmissions I'd recommend something with an overdrive. We're putting a similar engine in a Camaro this winter and my buddy is going with a 700R4. It's an easy swap and is going to allow him to use a little more gear for around town fun and still be able to take it out on the highway. Just my two cents...

 

[Car Nut]

There's no replacement for displacement, I would go with the 400.​

 

[Dale Davies]

First off this is not a Mopar, but I was hoping the engine GURUS could help me decide on which engine to purchase. Both are in the same HP range, although the 396 does have a couple more points of compression, which may not use pump gas. Both are built from the same new casting 350 block, and both are in the same price and HP range.

I am ordering a long block because I already hve an ignition and pla on using the performer RPM Airgap manifold.

The one I am leaning towards is this one, it is a 350 stroked to 396 with 6.0" rods and a 4.0in" bore. Forged crank, rods, and pistons.

GM SB Compatible 396 c.i. Engine - 491 HP - Long Block

Or

This one which is also a 350 stroked to 400ci" with a 4.125' bore and a 3.75" stroke also using a forged crank, forged rods, and forged pistons.

GM SB Compatible 400 c.i. Engine - 500 HP - Long Block

I am leaning towards the 396 because of the 6" rods, however I have no clue why because I am dumb as a box of rocks on the math of what works or does not work.
I may have read somewhere or picked up from conversations that a 6" rod is preferred.

They should just make one with 6.123 rods and a 4.040 bore and that would be easy, lol.

Thanks in advance!

Rod length can be like bringing up polytics or religion. Ask 5 guys and you are liable to get 9 answers.
Find the David Vizard Powertec 10 episode that discusses his cam LSA selection formula. There are a couple.
Now this will mess in a couple of guys Corn Flakes, bit DV determines LSA by his 128 formula; LSA = 128 - (cyl displacement ÷ (intake valve diameter × 0.91)). Now this is a starting point as there are things that require a little correction. The main is CR, a high CR requires 1° more LSA. A quick off the seat or higher ratio rockers may require 0.25° to 0.5° more LSA.DV states that testing on a Prostock engine with rods up to 1/2" different length only made maybe 10HP dfference. On a 1,000+ HP engine, that is within testing error range.
A longer rod will run slightly quieter due to less piston slap.
Look for another DV Powertec 10 youtube on running 14:1 CR. Octane of water is pretty much infinite. DV mentions a water injection system but there are others. Being you are in Texas, freezing is not a major concern, so running distilled water is an inexpensive option. Use a fair amount of water when vacuum drops. Small throttle opening is not prone to detonation. During phase change from liquid to gaseous state, water absorbs huge amounts of heat, cooling the combustion and preventing detonation. During this phase change, water expands 1,600×. This is how a steam engine functions, so that steam aids pushing the piston down. This would be much less expensive over the long term. If freezing temps are forecast, a gallon of methanol added to the water tank will keep it from freezing. May only need a quart. Add about 2% water soluble oil that machine shops use to help lube the pump and prevent corrosion.

 

[Dale Davies]

If you're changing transmissions I'd recommend something with an overdrive. We're putting a similar engine in a Camaro this winter and my buddy is going with a 700R4. It's an easy swap and is going to allow him to use a little more gear for around town fun and still be able to take it out on the highway. Just my two cents...

With the 3.07 first gear helps get things rolling. Depends on expectations.
PHR magazine went through a 1984 Malibu wagon that had a leaky 305 4 barrel engine and TH200 transmission. They rebuilt the engine with a 3.75 stroker crank for 334 CID and installed a 700R4. It was under 16 seconds in the 1/4 with 2.56 gears. Fuel economy was real good. Now in a truck, 3.42 gears would be good.