Technical High altitude engine build?

I've heard that there's a difference for building an engine if you live in thin air versus living at sea level. If so, what's the difference? I know about the jetting on the intake but what about compression ratio, timing, more air, etc.? Thanks!

 

I try to keep my altitude at about zero when I'm driving. But I live at 4500 ft elevation.

you can run more compression. Although then you get the joy of lots of pinging when you go visit the lowlands.

And having a blower helps.

 

Jim is correct except for the altitude part, I am normally @ about 5,000 ft. myself.

More compression helps, free slowing heads if you are running naturally aspirated and more CFM. You need to get more of that thin air into the engine anyway that you can. Cubic inches and boosting is a good idea, either with a blower or turbos ( yea I know that turbos are not popular on the HAMB).

You absolute easiest way to overcome the altitude is cubic HP and boost.

 

The first turbocharged passenger car was the Oldsmobile Jetfire option on the 1962-1963 F85/Cutlass, which used a turbocharger mounted to a 215 cu in (3.52 L) all aluminum V8. Falls in the traditional year rule.......

 

I remember those engines,even w/o the turbo they pushed that little Cutlass pretty good.

 

Rick help me out here did the turbo corvair happen after the jetfire or at the same time. I had a turbo '65 Monza Spyder, and if you know I am curious.

 

Those jet fire engines were also pretty high compression and ran a "rocket fluid" ADI system too. I've only read about them so anything I add would be regurgitation but they are intriguing and would love to study one.

 

Old VW bugs had an altitude compensator built into the carburetor that changed the fuel mixture to allow for air density. It worked pretty good too.

 

Corvair came out first with a turbo but Olds F-85 came out right afterward, either the same year or the next year. From memory, it was 1961 or 1962. But Corvair was first, if only by a few months.

 

McCulloch's first blowers in the 30s were aimed at Ford truck users at high altitudes. In the fifties they put blowers on gas powered semis, more to regain lost power in the mountains than for a power boost.

 

Rusty,
Thanks for the info on the 'vair. It was just a curiosity for me.

I thought that the first blowers on Diesels were on two strokes to blow the fumes out of the crank case. Was that to overcome altitude?

 

the Detroit two stroke diesels had blowers to make them run at all. It blew fresh air in, and the exhaust out.

late in the production run, they put turbochargers on some of them for added power

 

I agree, the thinner air (approx 3% loss for every 1000 ft) means you can build an engine with more compression. More squeeze of less air to get back some of the loss. Any tricks to get more air/fuel mix in the cylinder that work at low elevation also have benefit at higher elevations.

Ever notice at higher elevations the octane of the fuel sold is lower than the std 87? It can be 86 or 85. Pay attention when you fill up at Bonneville, it is lower octane there for example. I live at 7100 ft and Albuquerque is around 5300 ft. and we have 86 octane regular here. Less combustion pressure due to thinner air means you need less octane to prevent pre-detonation or pinging.

 

Turbos - Mallicoat Brothers Willys Gasser

Go here: http://wildaboutcarsonline.com/memb...352579483/1965-05_HR_Mallicoat_Gasser_1-4.pdf

 

I'd think a properly controlled blower (or turbo if it doesn't bother you too much) would be the best bet, and that the electronics would compensate for fuel / air mix and boost from sea level to the Rockies. Gary

 

I know Gary & Jerry - Gary lives less than a mile from our Prescott house. I'm more interested in the components of the engine than installing power adders (blower, turbo, nitrous, etc.). So I now understand more compression is needed because there's less combustion pressure with thin air. So you'd want to stuff as much air in to give it a bigger bang... is that right? Thanks guys!

 

I think turbos were used on diesel engines before they were used by Corvair. Shortly before the turbo Corvair came out, Barney Navarro built his own turbo Corvair using a diesel turbo.

One of their advantages was that a turbocharged engine does not lose power at high altitudes.

 

You can get away with higher compression, you may not necessarily want to set up the engine that way, if you will ever be driving where you can't get good enough fuel to run it without knocking.

There really isn't anything special to do to make an engine run at higher elevations. At least, I've never done anything. aside from my fetish for big blocks

 

Lots of WWII aircraft used turbos - B-17, B-24, P-47 (radial engines) P-38 (Allison V-1710) to name a few. The Merlin used in the P-51 was mechanical drive centrifugal supercharger. All used to compensate for 'thinner' air at altitude

 

Unless you never leave the mountains or plan to sell it to someone who also never leaves, build it for sea level. I've carried a distributor wrench and adjusted for cool or hot days and I've added water injection. I've also had a hammered wrist pin break the end off a rod when my brother took the car to sea level. Not worth it to push over 9:1 on regular or 10:1 on premium.

 

Guess if I'm blown, then I can spin the blower more at higher elevation than at sea level. That's probably what I'll do because I'll be going back and forth. If I built it for one elevation, it'll suffer at the other and vice versa. Thanks again!

 

Ever see "two lane black top"

 

Yes, what're you saying?

 

Jim, what do you mean by keeping your altitude at about zero when you'e driving? Thanks.

 

On their cross country trip, becauseElevation changes he keeps changing carb jets.

Air fuel ratio will change, computers solved that.

Squirrel's distance above the ground is altitude and he keeps that close to zero.

 

There is a thread right here on the HAMB with a guy rebuilding one that has some info on them.

http://www.jalopyjournal.com/forum/...oration-turbo-charged-fluid-injection.924403/

 

Turbo Corvair and the Jetfire Oldsmobile both came out in 62.....the corvair a few weeks before the Olds.

 

I put quite a few miles on my 55 with an Air/Fuel Ratio gauge (wideband O2 sensor). There is some change in AFR with elevation change, but it still runs a tad rich all the time. That's how normal performance carburetors work. I've taken the car on several cross country trips, including drag racing at several strips in one week...and never found any reason to change jets.

Be aware that movies are movies, they have a script, they don't have much reality.

also it's good to see that someone finally figured out my altitude vs. elevation joke.

 

I rode my old Harley up to the top of pikes peak, it wasnt exactly in the best tune the entire trip. But that might fall into high altitude category.

I noticed a loss of power on every thing when I was there. Had to trade my 94 cube van for a diesel, that SBC couldn't get out of its own way at that elivation. Maybe if I knocked a few 1000 lbs off ?

 

When I run my car at Tucson it's over half a second slower than running it in the midwest, or even Phoenix. Tucson drag strip is over 3000 ft elevation.