How much boost can one throw at an engine before having to go with O-rings and stud girdles, and all those reeeealy expensive bottom end parts?

Thanks

K

I ran 25 psi in my completely stock 2 liter 4 banger. I would think 15 psi with 8.0 - 8.5 static compression would be no problem. You could go even higher with a good intercooler. I'd make sure to use quality head gaskets and head studs. You want to avoid detonation and lean conditions at all costs so make sure you tune it up good and run good fuel.

Hmmm. Interesting. I have all the expensive bottom end stuff. My only drawback is that I have a 2-bolt main block. What do you think the max boost I could run on that would be? It could be a while before I get my blower rebuilt. I know it will be fine for my turbo right now though, Its only supposed to push 10.

It is the actual power level of the engine and the strength qualities of the particular engine, not the measure of boost psi, that will determine what equipment should be used in a super/turbo engine buildup.

Keep in mind that boost psi is just a measure of backed up airflow in the intake manifold, boost psi is NOT a measure of airflow. Here is an example to make the point: on a super/turbo engine if you swap out to better flowing cylinder heads you will "see" a decrease in measured intake manifold boost psi, yet horsepower increased. This is because actual airflow (the creator of horsepower) increased.

Taken one step further, different engines are known to need certain upgrades at different power levels. I.E., a big block has a stout

On my SC 468 there are no o-rings or head studs (and just a simple hydraulic flat tappet cam too!). If I were to seriously run it just past the current power level I would want head studs. If I were to run it ~1,100 hp and beyond then I would o-ring it. Beyond ~1,400 hp and I would prefer an aftermarket block.

Big blocks have stout bottom ends, small blocks need more bottom end strength improvements for any given same horsepower level. It goes on from there, I'm sure you see where this is going.

Thomas

Basically, I am looking to add a pair of hairdryers to a V6 for the Chevelle. I'll probably start with a Vortec 4.3 out of an S10 or whatever, and build from there. I'm not looking for crazy 1,000 HP, just something in the neighborhood of 400-500 or so. And yeah, I know, a big block could do that..yadda yadda...cheaper...yadda...off the shelf parts... yadda whatever.
Me, I like things that are DIFFERENT. Plus it would be WAY lighter on the nose of the car which won't get in the way of trying to turn the thing.

What does a stock GN reach on the boost gauge? (are there any stock ones left? smile.gif ) I'm guessing around 12-ish, and that is good for what, 275HP? With some camming, manifolds, a little headwork and sequential fuel injection, I'm just wondering how close I will be able to get to my goal without having to resort to extreme engine building.

K

K, no one here picking on you that I see. I think you will actually find that more people are interested in seeing the unusual buildups done than not - although most people will do the more common engine buildups for their own projects. Hey, its your bar of soap so go ahead and rub on it as hard and long as you want.

The GN SFI Turbo 3.8 Buick was good for 235 hp and somewhere in the 300's on torque. I believe the Sy/Ty turbo 4.3 hit 285 hp and 360 tq.

Twin hair dryers are not needed to get 500 hp from a 4.3 V6. Start your internet fingers hunting down all of the GMC Syclone/Typhoon web sites and you WILL find 1,000 hp 4.3 based turbo terrors.

Be sure to upgrade the pistons, the Vortec 4.3 comes with hyperutectic pistons that are not the best choice for a boosted engine - but the Vortec 4.3 heads are much better than the earlier non-vortec head.

Thomas

Like Bomber said, build it the way you want. I've been a believer in forced induction, turbocharging specifically, ever since I bought my first Eagle Talon TSi AWD turbo new back in 1991. The last turbo car I had was a 1992 Plymouth Laser RS Turbo AWD. See pics of how I modified it here (http://www.imagestation.com/album/?id=4291664427) if interested. I ran 12.0's all day long in that car on street tires, no weight reduction, and it was my only vehicle other than my El Camino. A few years back I had a Stealth R/T Twin Turbo that was also my daily driver. Ran high 11's. Again, with no weight reduction. Those cars are heavier than Chevelles. I think your turbo 6 idea is a great one although I'd do a single turbo for simplicity. I saw a 67 Vette with a GN engine transplant running low 11's. Quiet as can be. Talk about stealthy.

Turbos are a great way to make power. There's nothing like the sound of a turbo under full boost. :D