While my friends car is getting the cage installed, he is pondering the build of his engine. He just got the 400sb back from the shop. He is hoping to dip into the low 10s high 9s. Which blown engine would you build, a high rev 377 with more reasonably costing parts, or custom parts in a 434 with more torque? The car will see the track mostly.

Engine parts on hand
6-71 high displacement blower
400sb decked, and splayed caps
Dart Pro One Heads 230cc and 76 cc Chambers
2.05 intake 1.65 exhaust valves
Two 850 Demons
Crower Cam 293int/299ex, .587int/.612ex at 114LS

Here is his project.
1966 Chevelle @ 3200pounds
Back halfed with 33"tall x 21" wide slicks
4.70 geared, T400, 4000 stall

Thanks, Tim

Since it's a mostly track car and it is a Chevelle I'd go 434. I'd only build a 377 if it were going into something lightweight that will be street/strip such as an S-10 or a Vega.

Since they're both going to be blown motors, torque isn't a huge issue. There is an efficiency issue here and bigger isn't always better with supercharged/turbo engines.

I had a Procharged 468 and later a ProCharged 540. The 540 did make more torque but HP was almost the same between the two. According to a well-respected centrifugal engine builder the 468 was a much more efficient sized engine. The extra weight/stroke of the 540 negated some of my hoped for gains.

With that said I don't know if a 434 versus 377 combo is the same comparison.I do know a 377 can easily put you in the e.t. range you're looking for. I built a ProCharged 406 that's pretty mild and is making 700 rwhp on 91 octane and no intercooler. I'd think even that power could easily run high 9's in a good chassis. Should run quicker than that.

Jody

Why not go in between? 406?

Originally posted by Slowpoke70:
Why not go in between? 406? Nothing wrong with that. As above, made good power for pump gas!

Jody

Thanks for the replies. I think Mark just wanted something unique like the 434. Then he realized the added cost (custom pistons, clearancing the block, and heavy metal to balance the crank.)

I'll let Mark know about the 406. It should be a happy medium between the two.

Jody
What was your 406 engine combo if you don't mind me asking? I know that there is a difference between a centrifugal blower and a 6-71. But, 700 rwhp on 91 octane without an intercooler makes me think. I guess I'm more curious about Mark's cam being more radical than he really needs.

Tim

406
8.9:1 compression
Eagle crank, rods, upgraded ARP bolts
Ross blower pistons
SPR plasma moly rings
Victor Jr. Heads, stage IV port from CFM Performance
Comp hyd roller .580/.612 with 242/254@.050 on a 114 lsa with 1.6 Crower roller rockers
Currently running Accel EFI manifold and FAST ECU; Ran just as strong with a Vic Jr manifold and 750 blow-through carb
MSD distributor and 6AL
1 3/4 headers and 3" exhaust
ProCharger D1SC blower @ 14 psi
water injection kit

By the way, he had a .555/.572 lift with 230/236 (114 lsa) hyd roller in it before and it felt really close to the same, except it had much better idle vacuum. Shoulda kept that cam but he wanted something bigger!

Jody

Thanks Jody


Tim

I might be building a 377 blown motor too, except using turbos.

http://www.chevelles.com/forum/ultimatebb.php/topic/4/23824.html

For a roots blower, I always heard that you should stay away from the standard GM 400 block with a roots blow application for a couple of reasons. Roots blowers make boost quicker and tend to be harder on gaskets. A GM 400 block has siamesed cylinders..so not a lot of gasket between the cylinders. Also, roots blown motors tend to run fairly hot and since the water jacket cannot go around the cylinders in the siamesed portion, cooling may not be as efficient.

I have seen blown 400's/4.06's before, just don't know if they are having the issues raised above.