Inliners International Forums General Discussion Blown and Injected Planning Stages for 292 with 10lb Boost...

I'm in the planning and parts gathering stages for my boosted 292 project. I've just ordered an exhaust manifold (kudos to tlowe) and a megasquirt kit. I'm planning on using a Clifford ram intake, and have sourced forged pistons as part of a rebuild kit.

One of the next large purchases will be the turbo itself; picking the size, trims, and A/R ratios will be the obvious problem, which will be simplified to a certain extent after settling on a brand. So, one fundamental question is experience with the different makes. Another is the turbo bearing system; this will be my wife's truck, so reliable cool-down periods are not likely to occur. I would assume that this would mandate a ball-bearing water-cooled turbo. True?

I'm planning on building the 292 bottom end pretty much stock, but the degree of head work is yet to be determined. I've heard others discussing lump ports, but am not sure that giving up the through-the-head bolt boss is advisable on a truck engine.

Lots of advice needed...

it is relatively easy to water cool a turbo on a 292. i did mine. at the rear lower drivers side of block is a water jacket plug. install a fitting to feed turbo and return to the water pump. tom

doug,use a water-cooled bearing housing,
a ball-bearing is over kill, std. bearing style will work great. on the street I would keep the bolt boss for better headgasket seal.
How much HP do you want?
You also want to know the dynamic compression ratio so you know what the static comp. shound be.
NEED: BOOST 10#
COMPRESSION RATIO ?
INTAKE VALVE CLOSING POINT ?

You could also wing shape the boss to help the air flow around it. Mild reshaping of it Or add to it to get even more of a wing shape.

I had planned to use the stock-like dished pistons of 7:1 compression ratio. I'm aiming for 350HP or so. While more would be fun, I don't want to be forced to build an expensive bottom end. I'll likely limit the RPM to 4800 or so. I had planned to airfoil the bolt bosses.

(Sidebar... In 1909 the various european aircraft manufacturers lambasted the Wright Flyer as crude because the interwing struts were not teardrop shaped. The Wrights, however, had not assumed that the teardrop shaped cross-section had inherently lower drag, but had performed windtunnel testing and learned that a 2:1 aspect ratio rectangle with rounded corners was actually more efficient as well as stronger.)

This engine is to used in a truck; a combination show and go vehicle. The usual usage will be just cruising, with the occasional blast to pass; some of the highway time may be pulling a trailer. I don't expect that much time will be spent at the upper end of the HP output scale.

I'm looking at 10 to 12 PSI of boost, limited by a wastegate. Since I've yet to think about a cam, I have no idea on intake closing timing. The engine will front a 700R4, which has lots of leverage for accelerating the truck, so I'd like to have the engine rev easily, but cruising implies steadystate torque will also be needed.

I've tenatively nominated the GT3582R as the most likely candidate at this point... Probably a .82 A/R exhaust. The engine parameters run right up the high effiency island of the map. It intuitively seems like too much turbo, but the smaller sizes all seem to put the engine parameters close to the stall region.

I think with 7 to 1 compression ratio, it will be really lazy,poor gas mileage,& so-- on.

8.5 to 1 is a more decent compression ratio.

Two cents

MBHD

I think hank is correct 7-1 will be very lazy when not in boost, 8.5-1 at 10# boost with mild cam is like 12.5-1, but should work with an intercooler or enough fuel.
10# boost is a pressure ratio of 1.68 and about 43 lbs/min. But I don't think a 292 will flow 43 lbs/ min at only 10# boost, more like 37lbs/min which is still about 370 HP.
A GT35 looks a little big ,a GT30 maybe fine or a 60-1 (I like this turbo) , but I would talk to someone at Turbonetics or Innovative turbos first.
Also use the biggest turbine wheel, (not A/R ratio) you can use since you want the boost to come in at a higher RPM for passing or blast down the road, not as a Drag Race type setup. Everyone tries to sell a small turbine so it spools fast at low RPM, this just feels good but
does not always work the best.

Just my thoughts-Harry

This thread is exactly what I need to research. I have the 292, now its time to start getting the parts. I was hoping to hit the 14lbs of boost. What would that entail?

Thanks,
Dan