Could use a little guidance on my build. Small block stuff

[MattP]

Thanks for clicking. I'm planning out how the build on the Dart will go and could use some guidance.

Currently it has a LA360 motor with Flat top pistons at 10.5-1 compression. Looks to be a fairly basic rebuild. A TCI Streetfighter 727 transmission with a manual valve body and an 8 1/4 rear end.


My ultimate goal is a built smallblock with forged internals and either a single or twin turbo setup making around 600rwhp. I've built turbo cars before but this will be the first mopar.

I have a few different options.

Option 1: Have fun with the current setup and run a 125 plate on it while building another motor. Probably a 408 at around 9-1 compression. Swap in the 408 and sell the 360. I'd probably run the 408 NA or with the nitrous for a bit before putting on the turbo stuff. I'm not sure if the TCI 727 will hold the new power and I'm fairly certain the 8 1/4 will not hold it even with the brace.


Option 2: See about dropping the compression on the current motor down to a more boost friendly 9-1 with a thicker head gasket and/or different heads and boost that motor. All the same drivetrain questions apply here.

I'm leaning more toward Option 1 because the current motor likely has internals that will not reliably hold 600rwhp. I'll be building another motor anyway and I feel I'm chancing hurting a perfectly good mildly built 360 that could be sold to help contribute to the cause.

What do you think?

What is the 360 worth carb to oil pan? It came to me as a less than 5000 mile motor and I've put maybe 500 on it. It's crisp and making around 300 rwhp according to the 12.98 pass it made last weekend.

If I'm going to be building a motor with forged internals, aftermarket heads, and EZ EFI, is there any advantage with using a magnum 360?

 

[kielbasa]

600 rwhp.....you'll have several thousands of $$$ packed into this engine - i wouldn't waste the money on a stock block at this point.

 

[SRT_DSTRHOLC]

I would look at a R3 block. They are around 3k. Then I would look to call San Diego Forced induction and they might be able to help with the turbo or even Steve Morris engines, they make kits or prochargers for the power you want. 600whp is a round 700-750 crank. It would be easier to go P1 or D1 procharger. Also I EZ EFI is not for forced induction. Either go CSU Carb or XFI or even Big3 fuel injection.

 

[crackedback]

Option #1 and no nitrous until you tune the current combo

That's what I would do.

 

[MattP]

600 rwhp.....you'll have several thousands of $$$ packed into this engine - i wouldn't waste the money on a stock block at this point.

I would look at a R3 block. They are around 3k. Then I would look to call San Diego Forced induction and they might be able to help with the turbo or even Steve Morris engines, they make kits or prochargers for the power you want. 600whp is a round 700-750 crank. It would be easier to go P1 or D1 procharger. Also I EZ EFI is not for forced induction. Either go CSU Carb or XFI or even Big3 fuel injection.

A "400hp" 408 with good internals plus 15lbs of boost will be pretty close and run on 93 octane. I've got a few of the needed pieces for the turbo setup from the last build and have local contacts to source the other parts from. If I didn't have those contacts your suggestions would probably be the way I'd go. This will be a 99% street car and turbos are easier on parts than na or nitrous so I'm not as worried about a stock block as I would be with those setups.

Thanks for the heads up about EZ EFI. I thought I had read it had a bar sensor. Looks like I'll be looking a little longer for that piece. Maybe that Professional Products Powerjection piece.

Option #1 and no nitrous until you tune the current combo

That's what I would do.

Sounds like we are on the same page. Thanks again.

 

[DaveBonds]

Option #1 and no nitrous until you tune the current combo

That's what I would do.

x2

I think a stock engine block will hold up just fine at 600hp on a turbo.

The reason being is that even though turbochargers have inherently high HP numbers, they are on a super lazy curve, because it comes in late. This is a good thing on hard parts and the power is there, when you can use it.

I would set up a magnum, to avoid the need for heavy metal oils.

I would also opt for 8:1 or 8.5:1 on a 408 stroked magnum or roller LA block to begin with, on some cometic gaskets with a 65 or better RMS cut on the deck and head for good seal.

The magnum heads are closed chamber, I'd go aftermarket there, maybe opt for some edelbrocks and go over them really good on a flow bench, port matched to a good single plane. The Magnum exhaust is good looking, but if you can't get the math right for 8.5:1, you could look for a roller LA and go with open heads. Preferably some early to mid seventies 360, for the better exhaust.

If you don't want to deal with a turbo hat and a carb that is good enough to hold up to 15-17psi, you can always build a box to go around the carb to pressurize the entire thing.

 

[DaveBonds]

Also, look into Holley Pro-Jection for inexpensive TB FI. I'm sure people are running them on boost with added signal from wastegate.