I just bought a 3.4 but i have to wait to get it untill tuesday. It has 170 K miles but was rebuilt around 120 k. I eventually want to put a turbo on this. Ive read that the stock cam is better for turbos than aftermarket ones. Is this correct? You guys have any advise on things to look for? Im going to put a 3500 top end on it eventually and i know that i will need stronger pistons, so i should just rebuild the motor with stronger internals correct?

 

if its got that many miles on, youre gonna wanna rebuild it anyway. 3x00 top end swap needs the pistons from the engine you got it out of, not just stronger pistons. read up on the posts about this swap, whether its 3100, 3400 or 3500, its all the same BASIC idea. and if youre gonna eventually do this stuff, just get the engine and all the stuff now and start on it, theres no point in dumping all that money into it, and then having to pull it again later and waste most of the money you spent on it the first time around. but i definitely would not just drop in an engine w/ 170k on the clock. if nothing more (and please do more, youll regret it) tear it down to the short block, regasket, new oil pump, waterpump, and all that other stuff.

 

its got 50k on it... yay math!

 

3.4 pistons will work with 3500 heads. ~11.75:1 SCR with 3.4 head gaskets. Good torque, but will have to be tuned.

3400 pistons and 3500 heads will be the best combo for you if you are planning on boost. This will give you the shortened runners , big plenum, and ~9.1:1 SCR with 3400 head gaskest (3400 gaskest are a must with 3400 pistons). 9.1:1 and the 3500 top end will be very boost friendly and a good combination N/A.

An aftermarket cam is just as good as the stocker for boost, just try to keep a tight LSA. Usually N/A motors like a wider LSA and that is translated into most aftermarket cams. IIRC the stock LSA is 109* and the 262 grind, for example, is 111.9* but has higher lift/duration. If you have a custom cam graound wioth the lift/duration of the 262, but narrow the LSA it WILL be better than the stock grind.

 

You have that backwards.

Forced induction engine like a wider LSA. This keeps the air/fuel charge in the cylinder instead of blowing it out the exhaust before the exhaust valve closes.

Ideal average for forced induction engines seems to be around 112 to 114 LSA, though depending on the allication there is some variance to this. An LSA above 114 will be in a high boost race only engine, as they tend to have too little overlap, for street driving.

A stock cam is not neccesarily better for boost, but is generally easier to match and make power with than the large lift, wide overlap N/A cams that are available.

 

I was told the opposite by a rep at Delta. I wanted a wider seperation angle for the last boost cam I ordered, and they suggested I stay under 112*. He based a grind for me off the 262 (212* dur .440 lift single pattern), and said that they would close the exhaust a little faster.

 

Could I make an imposition and ask (pretty please) if you could turn this into a how-to 3.1 -> 3.4 thread? Maybe take a few pics and put up the steps you take?

 

There already is, called "The 3.4 Swap Boogie".

 

Find a new cam supplier or rep at least he has no clue what he's talking about saying that a tighter LSA is desired for forced induction.

If the tighter LSA was desired, I'd have a Shnieder cam on the shelf, as there is one that is perfect, other than the LSA, it's only 108, way too tight for forced induction, probably decent for a nitrous combo, would work well with a high compression N/A combination though.

I might use something at 110 or slightly tighter on a low boost street combo, where low RPM off boost responce is more important than ultimate power production up higher in the RPM band.

 

Yeah, I was playing with Desktop Dyno and 114 or 118LSA makes a lot more power than 110. I know it's not accurate, but gives you a good idea

It says my motor should make 317bhp 275tq at 7000RPM, we'll see how close it is. It was close on Dave's 3500.

 

Wider lsa is much better on boosted engines. The less valve overlap you have the less boost you're going to loose out the exhaust. The stock cam makes a good choice for mild builds because it has no valve overlap (at .05"). There's better cams out there, but if you really want to get the most out of it spend a little time designing your own with a dyno program. Look for the most area under the power curve, not peak numbers.