Thread: How do i get 400 hp from a 355?

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If you are running headers and a 750 Holley, I would guess that you are not using the ECM anymore. If that is the case, and you want to make 400 flywheel horsepower, you can do that easily. Making 400 horsepower at the wheels is a whole different story.

Assuming you meant 400 flywheel horsepower, and not knowing what your cam is, I will bite and offer some suggestions.

You said that you were running the stock heads, so your engine has about 9.1 to 1 compression. That is sufficient for the street.

Your heads are an unknown. In order to make good horsepower, you are going to need a set of heads other than stock smoggers. This is where you will make your power, so spend your money here. You could EBay or go to Summit. Sportsman II's by World Products or any of the AFR's are good heads. There are many, but those two are definitely good.

As for a cam, with the setup you have I would look at something similar to the Comp Cams CCA-12-212-2. It would work with your stock torque converter and has a good power range. If the specs of the cam that you have are similar, use it. Otherwise, replace it.

Your pistons are crap, but if you are on a budget and don't intend to add nitrous or race at the drag strip, they will work. If you have the money, a set of hypers for non-nitrous, or full forged for nitrous would be another wise place to spend money. If you are going to replace the pistons, I would seriously consider some flat-tops instead of the dished ones that you have. Don't try to run flat tops with the stock heads though. That would put your compression at a point where pump gas might not be sufficient.

Last but not least, your distributor was designed to allow the ECM to set the ignition advance curve, but you are not feeding the ECM. You will need to replace your distributor with one that uses vacuum advance and flyweights from an older model if you haven't already done that.

These suggestions are only educated guesses. If you could provide more information, we could help you better. I would also suggest that you go to amazon.com and buy David Vizard's book "How to build Max Performance Chevy Small Blocks on a Budget". It is a great source of information, and has 10 different engine combinations that they built and dyno'ed which put out as much or more horsepower as you are looking for.

I only agree partly with this last post.

Firstly, cast pistons are not crap. If they were such crap then the factory wouldn't use them and for dependabilty vs. performance, cast pistons are nothing to be ashamed of. I've seen stock motors go upwards of 300,000 miles and still running.

Second, there are some stock heads that perform very very well. For example the 461's are a fabulous head for a high compression small block. The 441's are pretty good for higher displacement engines. I'm using 441's on my 4.155 bore 377 cui ground pounder.

I also don't see where the distributor currently in use is shown.

Also, there's NOTHING wrong with running a flat top piston. They are made for higher compression that dished, but, when paired with the right chambered cylinder head, can run low enough compression that 90-93 octane gasoline would be sufficient.

I run a 4.155 bore with a 72 cc head and my compression is around 10:1 which is, btw, in range of pump gasoline.

But of course, it all depends on your budget. If you have a few grand, there's a lot of things you can do to make that 355 push 400hp. But if you only have 20 dollars and a coupon for a free slurpy at the local ez go, then your probably not going to get anywhere.

Power = Money, how much do you have?