Z28Drifter348

I have been in the process of my lq4 build for my z but recent injector failure in my lb7 duramax (DD) has moved it to the back burner until next month. So I have been looking at TSPs 408 rotating assembly. Part #25-tsp408RA. My original plan was to keep stock displacement and just do forged rods, pistons and stock crank and use my milled 62cc TFS 220 heads and an ms4 cam. But for the price of the tsp rotating assembly it's not much more than what my expected cost was for the original build. If I were to do the 408 assembly and my tfs heads and an ms4 what are you guys thinking the hp/tq difference is over my original plan. Pros vs cons. any advice/knowledge would be appreciated. Thanks in advance.

mark21742

You will gain a little more peak HP and tq, but where the extra cubes really help out is lowering the rpms where your power really starts coming in and will give you more all the way through the entire rpm range...plus the larger cubes really eat up cam duration so it will have great street manners

Z28Drifter348

So basically it will only have a little bit of a higher peak hp/tq but I will have a more usable torque band from say 3500-6600rpm? I plan on going for as high of a comp ratio as i can atleast 11.2:1 Currently planning on using an ls6 intake but would a fast 90 really make that combo shine or is it not a big difference?

bww3588

iTrader: (49)

An ls6 intake will horribly choke that engine. I would say at least a 90 would work great. Also, there are way better cams for a 408.

mark21742

If you go for a FAST set up, is spend the extra money for a 102... An ls6 intake will hold you back like BMW said, so if you have an ls1 intake now I'd just hold off, save up and go right for the FAST intake upgrade...but if you need an intake right now an ls6 would work, it would just hold a lot of your potential back a hair less than an ls1 would.

As far as cam the ms4 should idle close to stock in the 408...I'm running a 255/271 in mine and have a resent idle at 900 rpms

Z28Drifter348

Ok I'm currently running the stock ls1 intake. I can get an ls6 intake off a friend of mine for 300$. If its gonna be that much of a restriction I'll go for at least a fast 90. What do you guys think of the heads tho? I had them on my old motor last season until I scattered it and had to get them repaired. (new valves,guides,milled,etc.) point is I already have them and have even more money into them so I would like to use them unless they are going to be a huge restriction as well.

mark21742

The heads are pretty good, could be a little bigger (around 245 or so)...but is run them

First thing I'd do is build the bottom end with the best parts you can get and bolt your old top end back on.
Next after that is save up for the intake and bolt it on.

Your heads will work pretty good, so is say keep them for last to change.

I've seriously been looking at either All Pro or Mast Motez heads....either perform insanely, but cost a butt load of money

Z28Drifter348

Yeah I'm not in a real big hurry to get it done and get it in the car. I already have a 5.3 in the car that I got for nearly nothing did a dirt cheap rebuild and threw it in and I have been daily driving it for the last week while I tore my truck apart for these f***king injectors which probably won't be in until next week. So like I said there's nothing I can do to it right now anyway. I think I'm gonna go for the 408. I want this thing to be a mean bitch lol

mark21742

I do love my 408 and am glad that's the way I went

Z28Drifter348

Mark would you mind telling me on here or a pm of your head/cam/intake specs/comp ratio and how she did on the dyno and 1/4? So I can get an idea of what it's all about. Lol

garygnu

SDPC is selling stock ls3 heads for $325 each.you can new fast 92 mm from TSP.

mark21742

By the way, currently I have no problem spinning mine to 8,000 rpms and might end up spinning it higher here later on if it is still making power