2v build option 1 or option 2?

[musclemustang65]

Getting things planned for a build. I will be using my current 2.1 kb with the new setup. Im torn between (money dictates what parts i can buy) getting a 5.3 big bore shortblock and using the stock heads/cams for awhile. Or getting a 03/04 cobra shortblock and can still afford heads/cams. Whats everyones opinions?

 

[Mike@TF]

i wouldnt worry about doing a 5.3...just do a forged 4.6 and .020 over or so.. and do heads and cams.. it will make more power than spending your money on a big bore stroker..

 

[1sikStang]

Getting things planned for a build. I will be using my current 2.1 kb with the new setup. Im torn between (money dictates what parts i can buy) getting a 5.3 big bore shortblock and using the stock heads/cams for awhile. Or getting a 03/04 cobra shortblock and can still afford heads/cams. Whats everyones opinions?

Personally if your getting a 5.3 stroker don't embarrass it with the small 2.1 kb blower. It's capable of way more. Your restriction would be the blower. If u do a 5.3 go turbo or mammoth KB. But a 03-04 cobra would be just fine for that 2.1 KB and you can be pushing 500+ hp and a have a monster street car.

 

[AntiHeightPunk]

that 2.1 isnt going to push enough air for any built motor

 

[musclemustang65]

I know the 2.1 isnt going to make huge numbers but i cant affor a bigger blower or turbo, but i have considered throwing a 100 shot on top of it. Honestly ill be happy with mid 500 range for awhile.

Also debating between the used cobra shortblock versus just upgrading my own pistons and rods.

 

[mysticoupe]

How about use the cobra block and get a 5l. Stroker kit for it? Ive seen cobras with stock eatons / 5.0 stroked putin down 500+ I would deff. Upgrade your block, you can find a teksid block pretty reasonably priced.

 

[Blkkbgt]

I know the 2.1 isnt going to make huge numbers but i cant affor a bigger blower or turbo, but i have considered throwing a 100 shot on top of it. Honestly ill be happy with mid 500 range for awhile.

Also debating between the used cobra shortblock versus just upgrading my own pistons and rods.

You can make really good power with a 2.1 and an inlet upgrade but you will have to spin the blower to the max rpm (18,000). Take a look here New inlet for 2V 2.1KB.... Take a look at the bottom of the first post. This guy made 550 rwhp running out of fuel. The guy who used to make that inlet actaully made 600 rwhp, I believe he stated it in this same thread.

The key to making good power with a 2.1 is an inlet upgrade and blower cams. In an effort to keep cost down KB made an inlet to keep the stock TB and choked the blower. That inlet will NOT allow the 2.1 to flow anywhere near its maximum CFM and usually limits power to around 500 rwhp and similar tq.

Another modification that will help a little is porting and smoothing the intake manifold which should add 20-30 more hp. When you start looking at how rough the casting is you can see why. Ontop of that you can also see that even with stock heads the ports on the KB manifold are smaller then the ports on the heads. Open them up a little, blend the area around the injector boss and you will pick up some power.

All I am saying here is that if you want to spend a little extra $$$ you can make good power with the little 2.1.

Lastly I would not bother with either of those options you listed for a built engine. I would simply pull your engine, keep the cast crank, add pistons, rods and a set of good rings (not moly). If you want to you can spend another $300 and get a teksid to drop around 70lbs.

 

[musclemustang65]

I already have the mammoth inlet on mine. I considered keeping the stock crank but wasnt 100% sure how much power it would hold. I found a set of trick flow heads new for 1,700 bucks locally. I also found the killer chiller cooling system that seems to work wonders