Engine build for 5,000' of elevation?

[irdave]

Hello.  I'm Dave.  Pretty new here.  I've secured a hand-shake deal on a '72 tii, with a reported 240,000 miles and which has been sitting, outside, for about 15 years...  So the whole thing is a bit rough.

 

It's coming with an extra tii engine that's already in pieces but only had 40k miles on it when it came apart.

 

This is going to be a completely fun car- it won't have to pass the wife test.  So until we get all the lost paperwork found, I'm stuck with mental masturbation...  Maybe you guys can help.

 

Anyone care to share any ideas on how much compression I can run if the car never goes below 5,000 ft?  I run non-ethanol premium in everything right now- it's available at a pump in town.  If I squeeze it a bit can I / should I use the stock fuel injection or switch to carbs?  I've got a line on 4 FCR Keihin carbs (best 4 stroke moto carb ever made), which I'm very familiar with tuning...  (If 2 is better than 1, then 4 is better than 2?)  I'd like to be able to roll up to about 7k rpm on a moderately regular basis...  It already has some Motorola electronic ignition...  Plastic intake, with one of them taped up- apparently it's cracked...

 

Anyways, any thoughts on the matter would be greatly appreciated.

Edited May 30, 2017 by irdave

[wegweiser]

The stock injection is going to give you seamless, smooth, effortless, no-drama performance equal to - or better than most multiple carb set-ups, unless you go silly with hurling cash at it.... the last 10 horsepower will be the most expensive. It always is. While I applaud your idea about using 4 carbs - creativity is great - I think you'll be disappointed, unless you toss a $400 cam, $900 pistons, $500 flywheel, and other bits in to it. Even then - you'll have a $8000 engine making only 30% more horsepower that commands constant fiddling. 

 

US compression (9.0-9.5-ish) should be good for 91-93 east coast pump gas. I believe Euro compression on the early motors was 10:1, and that's what I run... but out west, I discovered ALL the fuel flat out sucks. Definitely watched my Ps and Qs with ignition timing the entire time I was out there.

 

Also - and just to throw this out there: a tii with it's original and complete, functioning engine is worth about 30% or more, when re-sale time comes. 

 

I've had silly, 180hp 2002s with all the expensive go-faster parts in it.....and yet a bone stock, but properly tuned tii is still my preferred mode of hauling holy ass. 

 

Embrace the original injection. Learn it. It's easy, but takes patience. Once it's set up - it can be absolutely goddamned bulletproof. If you want to tinker with multiple carbs (and hell yeah, they're fun and cool and make all the right noises.... I get it!) Find a non tii and sell this one to fund the hotrodding.  Early plastic-runner tiis are special cars. There's a visceral driving difference to them, even when compared to late 72 metal runner cars. Trashing the injection on an early VIN tii would be like peeing on the Mona Lisa - and I say that as a guy that appreciates creative, cool, brainy modifications to cool old cars... not just originality. A stock, healthy, properly tuned tii will haul at 90-100 mph for 7-8-11 hours at a time, humming along at 5000 rpm....and rev beautifully to it's 6400 redline. 

 

Just my thoughts. 

 

 

Edited May 30, 2017 by wegweiser

[Glen Karr]

Well said Paul!!

[markmac]

Paul, not ALL the fuel out west sucks.  You just need to know where to look if you are running above 10:1 CR.  Cheers.

[wegweiser]

...and it's only $8.99 per gallon! *FUT DAT!*

[markmac]

No, I hear you, you didn't specify (price).......you could probably knock 80 cents off that at current.  Of course the Californiai jackwagons just passed ANOTHER friggin tax (gas tax) to pay for the "infrastructure lie" but then thats another story-so it won't be less going forward........I digress.  Back on task now.......aside from the fuel comment, what Paul said....

Edited May 30, 2017 by markmac

[irdave]

9 hours ago, wegweiser said:

I've had silly, 180hp 2002s with all the expensive go-faster parts in it.....and yet a bone stock, but properly tuned tii is still my preferred mode of hauling holy ass. 

Thank you for your input; I'll keep it in mind.

 

You're running 10:1 at sea level?  We lose 3% of air pressure per thousand feet- so I'm down 15% just sitting here, and it only goes up- that's why I'm wanting to turn the pressure up a little bit with some more compression...

[jimk]

The fuel octane rating is lowered for high altitudes as well.  Cylinder compression pressure is lower as noted due to lower atmospheric.  So compression ratios used at sea level are the same used at altitude - the gas octane rating can't handle higher ratios.

(Cylinder pressure is atmospheric in psia  x compression ratio.  Do the math - 5000 ft  is a little over 12 psia.)

[irdave]

Thanks.  Looks like I'll try and get this 240k mile tennis ball up and running and see how flat it is.

[Conserv]

11 hours ago, wegweiser said:

The stock injection is going to give you seamless, smooth, effortless, no-drama performance equal to - or better than most multiple carb set-ups, unless you go silly with hurling cash at it.... the last 10 horsepower will be the most expensive. It always is. While I applaud your idea about using 4 carbs - creativity is great - I think you'll be disappointed, unless you toss a $400 cam, $900 pistons, $500 flywheel, and other bits in to it. Even then - you'll have a $8000 engine making only 30% more horsepower that commands constant fiddling. 

 

US compression (9.0-9.5-ish) should be good for 91-93 east coast pump gas. I believe Euro compression on the early motors was 10:1, and that's what I run... but out west, I discovered ALL the fuel flat out sucks. Definitely watched my Ps and Qs with ignition timing the entire time I was out there.

 

Also - and just to throw this out there: a tii with it's original and complete, functioning engine is worth about 30% or more, when re-sale time comes. 

 

I've had silly, 180hp 2002s with all the expensive go-faster parts in it.....and yet a bone stock, but properly tuned tii is still my preferred mode of hauling holy ass. 

 

Embrace the original injection. Learn it. It's easy, but takes patience. Once it's set up - it can be absolutely goddamned bulletproof. If you want to tinker with multiple carbs (and hell yeah, they're fun and cool and make all the right noises.... I get it!) Find a non tii and sell this one to fund the hotrodding.  Early plastic-runner tiis are special cars. There's a visceral driving difference to them, even when compared to late 72 metal runner cars. Trashing the injection on an early VIN tii would be like peeing on the Mona Lisa - and I say that as a guy that appreciates creative, cool, brainy modifications to cool old cars... not just originality. A stock, healthy, properly tuned tii will haul at 90-100 mph for 7-8-11 hours at a time, humming along at 5000 rpm....and rev beautifully to it's 6400 redline. 

 

Just my thoughts. 

 

 

 

Wow, Paul!  As Glen already said, beautifully-articulated.  Makes me want to buy a tii.  Oh, shoot: I already did!

 

Best regards,

 

Steve