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Pete. (l33t FS)
Pete. (l33t FS) MegaDork
3/12/21 2:47 p.m.
BigIron said:
Pete. (l33t FS) said:

You're looking at doing an old school low-tech turbo build, so I'd look into what old school low-tech endurance racing turbo engines did.  Lots of cooling INSIDE the engine: rich mixtures, remarkably low compression.  A lot of those old turbo engines would run so rich that the exhaust was barely visible and had compression in the 6:1-7:1 range.

Wanted to come back to this as it raised another question; E85?

I know a lot of turbo guys use it not only to run extra boost but also because it burns cooler. Don't turn up the boost and it may be a big help keeping the combustion chambers happy.

The downside is one will burn at least 25% more of it. I'd have to run the numbers but unless one has a Vette with 26 gallons that definitely wouldn't be workable. Short of running insanely fast laps to make up at least one extra fuel stop.

 

 

 

It would help immensely, but you will still need to address the cooling system so you aren't constantly burning out head gaskets/cracking heads.

That the SBC became America's de facto race engine was for many reasons and none due to its suitability as an actual performance engine.  Everything about it is wrong from a performance standpoint, but the relevant issue here is how there are two exhaust ports right next to each other, and this area will run hot and cause problems, even without a turbo.

BigIron
BigIron New Reader
3/12/21 3:00 p.m.
DirtyBird222 said:

Just put a K-series in a BRZ or Miata and have fun with way less headaches. 

The likelihood of me running a BRZ or Miata, let alone with a K swap, is nil.

A Chevette with a boosted 2.2 Ecotec would interest me more. Or Monza/Vega with same powerplant. (The factory turbo 2.0 doesn't work as a swap with Champcar. A 140hp 2.2 does with ease. Add ones own turbo)

edit-Perhaps some decent Challenge builds there?

Frankly, those would be much simpler than what I am contemplating I'm sure.

 

 

 

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
3/12/21 3:09 p.m.
BigIron said:
DirtyBird222 said:

Just put a K-series in a BRZ or Miata and have fun with way less headaches. 

The likelihood of me running a BRZ or Miata, let alone with a K swap, is nil.

A Chevette with a boosted 2.2 Ecotec would interest me more. Or Monza/Vega with same powerplant. (The factory turbo 2.0 doesn't work as a swap with Champcar. A 140hp 2.2 does with ease. Add ones own turbo)

Frankly, those would be much simpler than what I am contemplating I'm sure.

 

 

 

Turbocharging an endurance engine is a very expensive proposition, both to do correctly and to go through the learning curve.  That is probably why they do not attach as many points, there is a lot of work for any potential gains and by the time you make it work, you may find that you are making less power than if you went for a naturally aspirated option, and with worse throttle response.

BigIron
BigIron New Reader
3/12/21 3:11 p.m.
Pete. (l33t FS) said:

In reply to BigIron :

Porsche made 1200hp with five liters, twelve cylinders (more cylinders per liter), port injection, extremely low compression, extremely large (laggy!) turbine housings for minimal thermal stress, and many MANY man-hours of R&D by a company whose primary occupation was an engineering firm.  I know they did give up on air cooling and went to liquid cooled cylinder heads, cannot remember if this was the 917 engine or if that was the 935.

Just because there is no computer does not mean it is not sophisticated.  IIRC they were using a rather complex mechanical fuel injection, and of course they had a small army of people to engineer and calibrate it.

Part of why they dominated Can-Am was because Can-Am was mostly people on a shoestring budget.

I agree with all of that. The point was I'm looking at 1/3, or less, the power output with a larger engine and modern efi. One would think it would be workable.

I may just go the traditional way as I know how to make that work. Turbo's are intriguing however and the point savings are tempting.

And yes, Can-Am was independent teams slugging it out for minimal purses until Porsche showed up and ruined the party.

The downside of essentially no rules.

BigIron
BigIron New Reader
3/12/21 3:29 p.m.
Pete. (l33t FS) said:
BigIron said:
DirtyBird222 said:

Just put a K-series in a BRZ or Miata and have fun with way less headaches. 

The likelihood of me running a BRZ or Miata, let alone with a K swap, is nil.

A Chevette with a boosted 2.2 Ecotec would interest me more. Or Monza/Vega with same powerplant. (The factory turbo 2.0 doesn't work as a swap with Champcar. A 140hp 2.2 does with ease. Add ones own turbo)

Frankly, those would be much simpler than what I am contemplating I'm sure.

 

 

 

Turbocharging an endurance engine is a very expensive proposition, both to do correctly and to go through the learning curve.  That is probably why they do not attach as many points, there is a lot of work for any potential gains and by the time you make it work, you may find that you are making less power than if you went for a naturally aspirated option, and with worse throttle response.

Probably a lot of truth in this. However, it has been done in Champcar. Years ago with a Honda that was promptly essentially banned, with a large points increase for turbos, and more recently by a turbo Miata under the current rules.

A lot of edgy stuff like this starts getting reliant on what track one is running I'm thinking. The turbo Miata was out west at a smaller turnout race, while blowing off an EC Mustang built and raced by Meyer Racing, a well known Mustang shop. Put that same car at Daytona and the results will likely be different due to fuel burn alone. It would have the speed to compete except for having to stop every hour on the hour.

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
3/12/21 3:40 p.m.

In reply to BigIron :

It should be pointed out that the Miata engine is more or less a turbo engine that Mazda opted to not install a turbocharger on.  (The B6s actually used the same bottom end as the B6T engine save for higher compression pistons) This is most of why it takes so well to turbos in the first place.

kb58
kb58 SuperDork
3/12/21 4:19 p.m.

I don't race in anything other than trackdays, but know some about turbos. Short answer: no to a turbo for this sort of event.

Long answer: I built an 1800-lb mid-engine car with a turbo Honda K24. Yeah, a lot of stuff broke up during development, but it ended up reliable, after a couple years. Than again, trackdays are often only 20-minute sessions, so who knows how that would turn out, pushing towards 12 or 24 hrs. 

Inconel studs, check; huge intercooler, check; a well-developed fuel map, yup.

If you decide to push on anyway, a couple bits of advice:

1. If it's remote-mounted, that takes care of nearly all the engine compartment heat issues. I say "nearly" because the increased exhaust back pressure will still make the exhaust system hotter, but the total amount will be far less with the turbo far away.

2. If you keep boost reasonable (<8psi or so), consider not running any intercooler, and instead add fins the length of the compressor outlet pipe, which would likely be about 8 feet long.

3. Absolutely use a turbo with water-cooled bearings.

4. Regardless of turbo or not, I agree with the previous comments regarding Accusumps - all the negative points, and all the positive points regarding dry sumps.

I'd really pay attention to the past event results. If V6s have done will over the years, that's a strong hint to use one. I also agree with starting with a light car. There are just so many positives that go with a lack of weight.

BigIron
BigIron New Reader
3/12/21 5:01 p.m.
kb58 said:

 

4. Regardless of turbo or not, I agree with the previous comments regarding Accusumps - all the negative points, and all the positive points regarding dry sumps.

I'd really pay attention to the past event results. If V6s have done will over the years, that's a strong hint to use one. I also agree with starting with a light car. There are just so many positives that go with a lack of weight.

 

I agree on Accusump vs dry sump. However the 100 points (simply ridiculous) makes that problematic no matter which way a guy goes. My idea, and this works with or without turbo, is to use 180 degree headers that go up and over. These are often used in circle track racing, available ready to go at reasonable cost, and will allow a massively wide sump that holds a large volume of oil. Of course it would have trapdoors and such to control flow, but the large kick outs will hold more oil and should prevent starvation.

And as noted earlier, there are a number of SBC's racing and surviving without dry sumps, so it should be good to go with the additional capacity.

I agree that smaller and lighter is generally faster. Being 6'7", with helmet, means I don't fit in small light cars very well and I really don't care for racing convertibles. And that is a huge negative for me concerning the C3 Vette, although it is the perfect car otherwise in my eyes.

I already know it will be cold and raining every time I get behind the wheel if I go convert. That's how my luck works and would rather avoid it.

Thanks for the advice. First hand experience is always good.

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