A few 5s questions???, yea i been thinking at work again Options

[macavely]

another boring nite at work so just sitting here flipping throw some mags.. and just thinking about some stuff...

1. That rebuild short block with the 11.0:1 forged pistions making 170 at the crank (thos numbers might be off) Whos as get it ? and how do you like it?

2. For you 5sfTe guys... everthought of custom 11 or 12:1 forged pistions with rods.. and running anywhere from 5-10lbs of boost ?

3. Who is playing around with the A/F mix... with no major mods ? and what are you gettin out of it?

4. and since this was asked about the 7a ... what are the limits of the 5s block... who has fooked there 5s by over boosting?

[Kwanza26]

When you talk boost... the same rules apply to any non-turbo engine with a custom turbo. Some are naturally stronger than others, but when it comes to max boost levels... it's all about fuel and tuning. On stock internals, I will say the same as I did for the 7AFE. I can see 15 psi very well tuned on the 5SFE for a weekend car, but not reccomended as a daily driver. Again, the stock internals aren't quite up to par... mainly the pistons. Unlike the 7AFE however, the 5S rods are a bit tougher because of the longer stroke. As for higher compression and boost, higher static compression will yeild more power from less boost, but the tuning is made much much more difficult and the room for error or oddities is much much smaller. Little changes in things such as oil temp, spark, fuel, mixtures, induction temp, etc... can cause massive failures with higher compression instead just "problems" in a set-up with less compression. The reason... heat. More compression... more heat. Heat detontates...

As for n/a build up... this is the catergory where the 7A shines over the 5S. The 5S block is an extremely overquared design. That's not a bad thing, because with taller strokes, the engine makes more useable torque... however, it also hurts the top-end performance because of piston dwell time, weight, piston travel, etc. If you look at nearly ALL of the high revving high powered n/a engines... nearly all of them have a short stroke... usually less than 87mm. Some examples, 2ZZGE (180-190 hp @ 7800 rpms, 85mm stroke), 3SGE (160-210 hp @ 6000-7600 rpms, 86mm stroke), K20A (220+ hp @ 8000 rpms, 86mm stroke), 4AGE 16/20V (110-165 hp @ 7000-7800 rpms, 77mm stroke), C32B (280 hp @ 7300 rpms, 78mm stroke)... and I can go on and on. Because the 5SFE doesn't have an ideal stroke value for revving, it doesn't get good benefit from a GE head, or head work, or really agressive camshafts. That doesn't mean the 5S has no chance of revving... no... but it'll require a lot more build-up before it can reliably hold revs in the high-power range. It's a much better set-up for boost though...