Greetings,

I've searched myself silly trying to find the answer to my own question, but I think the best thing to do now is fess up, and ask the experts for an opinion.

I'm installing an '86 spec TII engine in an airplane, and I plan to use an 89-91 (S5?) turbo assembly to provide some altitude compensation up to about 14k feet. The intake will be either made from scratch, or modified from the original manifolds. The exhaust system will likely be non-existant. In other words, there would only be a short section of SS pipe from the turbo.

Here's the (first) question- At 7000 RPM, with my open exhaust, how much boost (if any) would you expect to see with the stock wastegate fully open? How about if the wastegate was ported?

FWIW, I'm thinking of using a manual control cable to the wastegate. It would be left fully open for takeoff and landing, but could be dialed up at higher altitudes to restore the power lost by the thinner air. My goal is NOT to boost the engine much above sea level pressure initially. After some testing, I might raise the boost for takeoff, but that would just be to show off

Thanks,
Rusty

 

atkins rotaries does turbo rotaries for airplane applications.

 

i would think you'd be better off with a Series 5 (89-91) turbo and manifold or possibly something a size larger than standard, i suppose it'll depend on how much load it gets as to what you can and cannont spool

 

I have a low mileage series-5 turbo and manifold already, so that's what I plan to use. I'm sure there are other aftermarket turbos that are better suited to the task, but they are so expensive, that it just wouldn't be worth installing.

I originally had two possible engine goals: a ported, high compression, NA engine, or a stock, turbo-normalized engine. I was leaning toward the non-turbo option, until I ran across the deal of the century. I bought a new (not rebuilt, not remanufacured, NEW) '86 spec TII engine for $2800, which included delivery from Canada, and no core charge. (don't ask, there aren't any more)

Even with the new (did I mention it was really NEW ) engine, I could use the turbo, or not, since the plane I'm putting it on is only meant to have 150 HP. I hope I can make the turbo work out, but it might not even fit in the cowling. At the moment, I'm desperately trying to finish up the structure of the plane, so I can get to the fun part, the engine. The other reason I need to finish the structure, is so I can move some of it to the hanger, and get my new R1 in the garage. Poor thing just got rained on by Thunderstorm Hannah

Cheers,
Rusty