Adding boost to high compression engines

alfadriver said:

frenchyd said:

In reply to kb58 :

That’s true about E85 some is mixed will low grade asphalt ( insert smiley face here to indicate joke) and ethanol while most of the stuff from people like VP fuels is mixed with higher grade gasoline.  

Which is why one should learn to distill their own alcohol for fuel.  Mix E100 with even 91RON E10, and you will still end up with E85 well over 100 RON.

Distilling your own Ethanol is a lot harder than making good moonshine.  It’s been too long since I was at an ethanol plant and I can’t remember the details  but as he said “moonshine isn’t even a good start”.  As for buying non-denatured alcohol  I wonder what tax on a 55 gallon of it would be!  

Then if you start with denatured alcohol that retails for over $10.00 a gallon. Add a little nitromethane in and you could really break the bank

bentwrench said:

from the "net"

 

Toluene is one of the higher-value molecules already in use in many gasoline blends. The main benefit is that it's an octane booster that does not dilute the energy content of the gasoline like ethanol does. It's a C7 aromatic molecule, which means it contains a lot of energy and vaporizes easily, but not so easily that it's an air pollutant like lighter benzene (C6 aromatic) and butane (C4) molecules, which percolate out of unsealed gas tanks and contribute to smog.

The tricky thing about adding aromatics is that the total quantity in your fuel shouldn't exceed about 30%, which is the sum of all the benzene, toluene, and xylene put together. Many regular gasoline blends already contain significant amounts of aromatics -- up to 30%! -- so there's no simple way to tell how much more you can safely add. As it happens, the higher quality gasoline blends (which supposedly includes Shell and Chevron gas but don't quote me on that) already contain a lot of toluene and xylene. Adding toluene is more likely to improve low-octane gas than high-octane gas. 

A rule of thumb floating around the internet is that you can safely add 10% toluene to your gas without causing engine issues. So that would increase your 93 octane gas to (93 * .9) + (114 * .1) = 95.1 octane.

But please make sure you really need higher octane! Read this first: http://en.wikipedia.org/wiki/Oct... or one of the many questions about octane. Toluene is a better octane-booster than many but it's not going to help if you don't need higher octane to start with.

 

My team found on the dyno when running a low compression restricted class we made more power with lower octane fuel.

 

From another article about bathtub chemistry

A. Benzol - A high octane ( 108 approx. ) hot - burning petroleum product.
Although benzol will auto-ignite, it serves as a coolant when added to the 
fuel mixture ( 10% by volume).

B. Ether - A highly questionable racing fuel. Although generally used as an 
igniter, it serves best - if used - as a starter fraction.

C. Acetone - Used generally as an igniter to boost top and RPM and 
acceleration. Has strong solvent action on plastics.
Acetone is also used as a blend stabilizer, plus a water tolerance
booster ( methanol blends, with 1% to 3% of distilled water added to 
mixture). 

Very interesting!  When I priced toluene it was about $45.00 a gallon.  In. 55 gallon drums.   I suppose when refining it in your own plant there are some really serious discounts available.  

In reply to frenchyd :

It may be harder than making moonshine, but I would wager that GOOD moonshine is harder.  There are plans out there that can distill alcohol to 90-95%.  And at that point, you can use some filters to take the rest of the water out.  Or leave it- as long as you don't leave it in, the remaining water probably isn't really going to hurt anything.

In reply to alfadriver :

Maybe I’m going about this in the wrong way.  The reason I’ve been doing so much research is I’m trying to decide which is the smarter approach to cheap power.  

I have a 250 cu in Roots type blower that I can easily adapt to a Jaguar V12 .  Jaguar made two 5.3 V12’s that they imported and I have several of each.

One has really good heads with only 7.8 -1 combustion ratio  that one is called the Flathead because there is no combustion chamber. When the valves open they open into the cylinder.   

The other has 11.5 -1 compression ratio but the valves are shrouded by the combustion chamber in the head.  

In normal aspirated form the Flathead produces up to  650 horsepower while the shrouded  one is pretty limited to 450 hp. 

The combustion chamber in the flat head is a bowl in the piston 

Race gas is well over $10.00 a gallon even in 55 gallon drums  while E85 is less than $4.00 usually closer to $3.00 a gallon in those same 55 gallon drums. 

Can I safely use E85 and a decent amount of advance with the 11.5 compression?  Nothing on my engine analyzer program can answer that

In reply to frenchyd :

Do you live near "pick your own" fruit farms?  Once they start going "bad"- you quickly ferment that.  The real problem is taking something that is rarely over 10% alcohol and getting significant amounts of 95%.   Would take many, many gallons of that to feed your V12.

In reply to alfadriver :

90-95 proof or % ?  

In reply to alfadriver :

I own an apple orchard. Most years except for a few pies and a handful of apples the squirrels and rabbits enjoy my crop. 

But there is no way I’d harvest the tens of thousands of apples needed to keep a race car fed

Just use E85 and call it a day.

There is a reason it's so popular.

parker said:

I can't wrap my head around this.  I have an FR-S which I love and have no intention of fooling with, I just want to expand my knowledge.  

Having come up in the '80s working on cars from the '60s and '70s adjusting points, setting dwell, messing with carbs, etc. I can't imagine how adding boost to an engine with 12:1 compression ratio doesn't just grenade.  And yet all sorts of kits exist for the "slow" twins.  How does this work?

A bud has an FRS on 5 pounds of eboost.  I've driven it, power feels really nice.  He liked the stock car well enough but just wanted a fatter torque band.   And he has it now.  Standard California premium fuel seems to work fine for him.

For a good example of a factory setup with a high CR, the new Mazda turbo motors.. 10.5:1 on 17psi.

And the folks at Flyin' Miata having a supercharged and turbo car on the NDs at 13:1.

Just takes careful tuning.

z31maniac said:

Just use E85 and call it a day.

There is a reason it's so popular.

OK then which way do I assemble it?  Shrouded valves and 11.5-1 compression or high flow head and 7.8 -1 compression and maybe more boost?  

Then another choice might be add a little nitro. 

Is there a way to get the compression up with the better flowing heads?  Such as different pistons and cutting them for valve clearance?  

In reply to rslifkin :

Yes at a cost that I’m trying to avoid. 

Don't overlook the fact that many of these modern high compression turbo engines are direct-injection. That change alone is responsible for much of the jump in power. The rest is due to really good ECUs

frenchyd said:

In reply to alfadriver :

90-95 proof or % ?  

% , 190 proof.

frenchyd said:

z31maniac said:

Just use E85 and call it a day.

There is a reason it's so popular.

OK then which way do I assemble it?  Shrouded valves and 11.5-1 compression or high flow head and 7.8 -1 compression and maybe more boost?  

Then another choice might be add a little nitro. 

Low compression and high boost

In reply to kb58 :

That’s my gut feeling  but the computer tells me the other way makes 42 more horsepower

How costly would 12 custom forged pistons be? Its not what you want, but it might be what you need.

frenchyd said:

wspohn said:

Yeah, the DI has significant cooling effect and allows you to run more boost that yu would otherwise.  I see 25 psi+ on my Ecotec.

DI also has it's own issues - carbon deposits on intake valves, and with a turbo engine you can't run any sort of cleaner through the throttle body, or it can kill the turbo bearings.

Even non DI engines can have significant boost with modern engine comtrols - an S54 BMW has 11.5 comprssion ratio and can still be turboed 

https://youtu.be/silQi_8x3gw

 

https://www.bimmerforums.com/forum/showthread.php?2123962-E30-S54-TURBO-1060-WHP-1130Nm-(833lbs)-1167WHP-E21

I’ve given the deposits in direct injection engines some thoughts. Deposits have to come from someplace.  I’ll assume that the air injected is clean, some sort of filters,ie no chunks of dirt.  

Then the deposits have to be a result of fuel.  Maybe fuel isn’t being directed down the intake anymore, but we all know about valve overlap.   We know what cleans deposits.  Alcohol!   

A fuel rich in alcohol will clean deposits. 

No fuel crosses the valves in a DI engine. The deposits in a DI engine are a result of EGR and crankcase PCV systems recirculating sooty, oily mix back into the intake and not having any fuel present to clean it off.

frenchyd said:

z31maniac said:

Just use E85 and call it a day.

There is a reason it's so popular.

OK then which way do I assemble it?  Shrouded valves and 11.5-1 compression or high flow head and 7.8 -1 compression and maybe more boost?  

Then another choice might be add a little nitro. 

If you're trying to avoid expensive, high strength parts, then keeping pressures low, and maximizing flow is the best path. Boost is pressure. Your supercharger will be supplying the same amount of air whether the heads flow well or not, but a better flowing head will allow that air to be processed at a lower pressure, and that should make the same power while keeping stress down.

Increasing boost with a roots means you have to spin it faster. That takes more power, and can create more heat. You need to get comfortable with an efficiency map for your supercharger, and determine how fast you'll be spinning it based on pulley sizes.

In reply to STM317 :

The really sad part of this is the parts in a Jaguar are extremely  high strength right out of the gate.  I’ve raced Jaguars and in a Chevy or most other cars you have to replace most  of the mechanical bits to get reliability.  

Not so with Jaguars.  I took junkyard parts slapped them together  with a few go fast bits and raced for 30 years + without a single failure. 

I wanna do it again!  

As far as  the blower goes it works very well on big block engines 125 inches bigger.  I’ll start at about 90% underdriven if the engine is happy and looks like I can increase boost I’ll swap the top and bottom pulley and be 110% overdriven. 

From  there I can swap as I feel the engine wants more.  Always remembering that the faster that pump spins the hotter the air gets.  No intercooler underneath to intercede.  

alfadriver said:

frenchyd said:

In reply to alfadriver :

90-95 proof or % ?  

% , 190 proof.

OK  ya got me interested.  Now are we talking about something I can whip together from junkyard parts or are we talking about the defense department budgets?  

 On the other hand I am semi serious about nitro.  I’m not talking about any serious amount  

You can buy a gallon at your local hobby store that is up to 45%  nitro ( most of the rest is alcohol).  Now mixed with 10-20 gallons of E85 we’re talking at best  2%?   

But would it help much and at what cost?  ( reliability and parts wise )!

I watched a couple of guys who’s tired old sprint car  was almost too slow to qualify add a percent or two of nitro and they finished third.  

frenchyd said:

z31maniac said:

Just use E85 and call it a day.

There is a reason it's so popular.

OK then which way do I assemble it?  Shrouded valves and 11.5-1 compression or high flow head and 7.8 -1 compression and maybe more boost?  

Then another choice might be add a little nitro. 

All the boost then if you aren't willing to get the compression up with the better flowing heads.

But I'm the kind of guy that replaces every bolt in the suspension with new when building a car, I don't believe in cheaping out like many.

In reply to z31maniac :

When I built for customers I only used AN grade bolts. Bolts that I could trace the origins back to the vat of steel that originated them. With every inspection documented.  

On my own I examined every bolt and piece and if under stress I either magna-fluxed it or zyglowed it. However  most parts had a decades long history of performance.  Besides my budget was chump change to most racers

Appleseed said:

How costly would 12 custom forged pistons be? Its not what you want, but it might be what you need.

The problem is where do I stop.  Last Racing V12 I built I went with Aries because they were light made with the right aluminum, had the proper tapered pins I sought etc.  Because they were so custom they were darn expensive.  

Now the best pistons for that application are made in England by Cosworth. They are 1/2 the weight, stronger, but most of all they have a unique chamber  that I haven’t seen anyplace else.  

However I have no doubt the cost would dwarf what I paid for the Aries.  But that’s just the start.  It’s real easy to add stroke to a V12, send the crank out to be offset ground. And buy Chevy rods.  And since I’m buying new pistons go as big as possible.  The sleeves come out and you chuck them in a lathe and now that little 5.3 liter engine is 7 liters.  

But I’ve spent $5000.   Knowing me I’ll spend another $4000 to go the next step and we’ll as long as I’ve spent that much——-