Forced Induction's FI91X report!

[d90dan]

Here's some pics of the air filter ducting.

Nice looking setup, Don.
At what level do you think the single filter is a restriction? I was running into problems with my filter collapsing (imploding?) running a 70. Killed my MPH.

 

[Alky V6]

Nice looking setup, Don.
At what level do you think the single filter is a restriction? I was running into problems with my filter collapsing (imploding?) running a 70. Killed my MPH.

This is a 14 inch long air filter. The filter calc'd out to flow just over 1600 cfm at a 3" water pressure drop. My hp target for the moment is just under 1050. Engine airflow CFM will be maybe 1200.

The intercooler is a different story. I did some calcs according to dimensions of the intercooler. It calc'd out at 725 cfm.

 

[ttypewhite]

AWESOME work Don, your workmanship is very clean and neat. Can't wait to see videos of this car once you have all the bugs worked out. Keep up the good work buddy, it will definately pay off in the end.

 

[Chevota]

This is a 14 inch long air filter. The filter calc'd out to flow just over 1600 cfm at a 3" water pressure drop. My hp target for the moment is just under 1050. Engine airflow CFM will be maybe 1200.

The intercooler is a different story. I did some calcs according to dimensions of the intercooler. It calc'd out at 725 cfm.

If you need a good source for a new, reasonably priced, custom I/C, lemme know. At 30psi I'm getting 54-59deg IAT's.

scott wile

 

[John Wilde]

Don,

I think I already bothered you with this before.
Why not just dump the intercooler?
How much is it really helping with a full alky motor?

 

[Alky V6]

I just ran some calcs. The first one was with no intercooler. The second was with an intercooler with the flow rated at 725 cfm and the efficiency at 55%. The difference was just over 100 hp. Even if the real world difference is half of that, I think for now I'll stick with the intercooler.

 

[Otto J]

Don,

I think I already bothered you with this before.
Why not just dump the intercooler?
How much is it really helping with a full alky motor?

I was just gonna post this also,Especially if he is gonna keep the
boost under 30,Which should be low 8s anyway.
Turn the compressor housing so it blows directly into the t body.
It will spool the best with no intercooler piping.
Less weight and less track maintenence also

 

[six shooter]

If you need a good source for a new, reasonably priced, custom I/C, lemme know. At 30psi I'm getting 54-59deg IAT's.

scott wile

I could use that for a house air conditioner !!

 

[Chevota]

I could use that for a house air conditioner !!

At 20lbs of ice every 45 sec I don't think so...

 

[John Wilde]

I was just gonna post this also,Especially if he is gonna keep the
boost under 30,Which should be low 8s anyway.
Turn the compressor housing so it blows directly into the t body.
It will spool the best with no intercooler piping.
Less weight and less track maintenence also

Otto,

I know Don has run the numbers but I would definitely ditch the intcooler.
What is the pressure drop going to be like going through that core?
Most of the 2500-3000hp turbo alky motors do not have intercoolers.
I am not sure that I am going to argue with their success...

 

[Alky V6]

Otto,

I know Don has run the numbers but I would definitely ditch the intcooler.
What is the pressure drop going to be like going through that core?
Most of the 2500-3000hp turbo alky motors do not have intercoolers.
I am not sure that I am going to argue with their success...

But... imagine what they could do with intercooling.

 

[John Wilde]

But... imagine what they could do with intercooling.

At some point you don't want the fuel any cooler.
Since we think the the new turbo is too much for the
intercooler cooler, wouldn't any temperature loss be offset by
pressure drop? Just trying to think outside of the box.
BTW the air intake looks nice, please update us when you change
the hose out =)

 

[Otto J]

But... imagine what they could do with intercooling.

Don these guys are running into the hard 6 in the 1/4 mile.I am SURE they have done their homework on this.
If an intercooler was gonna give the guys running at that level even .05 they would have one.

 

[SGRIM]

I know a FULL RACE GN that is NOT going to have a IC on it

You don't wont it but so cool...

 

[Alky V6]

At some point you don't want the fuel any cooler.
Since we think the the new turbo is too much for the
intercooler cooler, wouldn't any temperature loss be offset by
pressure drop? Just trying to think outside of the box.
BTW the air intake looks nice, please update us when you change
the hose out =)

You're right. The intercooler does calc out to be too small. At my present level of testing (24 psi), I'm not worried too much about it holding me back. When I start pushing the boost, I'm going to start taking some pressure differential, and temp readings. I setup an access boss on the pipe before the intercooler for measurements. If it does turn out to be holding me back, don't worry. It will be eliminated or most likely changed out.

 

[Alky V6]

Don these guys are running into the hard 6 in the 1/4 mile.I am SURE they have done their homework on this.
If an intercooler was gonna give the guys running at that level even .05 they would have one.

I see your point, but let's compare apples to apples. In the first place, they have a lot more cubes on me. They can afford to lose a little hp by having to richen their mixture to make up for the loss of intercooling. In fact, a lot of the high end alcohol racers will search for that detonation limit and the good ones will tune their engine practically right on the detonation limit. I'm tuning my engine alone. No help from alky racers with tons of knowledge, let alone knowledge of burning alcohol with a Buick V6. Others that have tried burning alcohol in a Buick V6 have gone through a warehouse of blocks trying to tune it in without intercooling. I'm low budget here, unless someone out there would like to sponsor an effort, I have to play it safe. Very safe.

It is the leaner alcohol mixtures that make the more power. Rich mixtures are used to cool the intake charge. The hotter the intake charge, the more fuel to cool the mixture. My experiences, so far with rich mixtures, are that the power suffers tremendously the richer you go. My BFSC is at 1.15. That is extremely lean for a supercharged alcohol engine. The engine likes the fuel strength, not to mention the cooler, intake charge keeps me further from detonation while allowing me to use a leaner, more powerful mixture. The cooler charge is also more dense. With my small engine I need all the help I can get to cram every air molecule I can into the engine.

My engine, right now, is tuned at a point that makes the most power at the safest mixture. When I go richer, I lose power. If I were to eliminate the intercooler, the first thing I would have to do to make up for the much higher intake temps would be to richen the a/f mixture. How many of you out there relish the idea of performing a tuning task where you know it will lose you horsepower, and possibly engine durability? Especially if you can't afford to pop an engine.

 

[Alky V6]

I know a FULL RACE GN that is NOT going to have a IC on it

You don't wont it but so cool...

Just make sure you start out your tuning effort very rich. As you lean into it, you will be amazed at how the power increases the leaner you go. Don't get greedy! When you find that detonation limit, you won't be able to pedal out of it fast enough with alcohol. It's not like gasoline where you'll get some pinging, or some numbers on your knock sensor to warn you. Alcohol will let you know when you've reached the detonation limit by folding your rods in half! Like right now.

Have spare parts on hand.

 

[Alky V6]

I'm not so sure about just how cold is too cold burning alcohol. I've just installed a turbo that has got to be a ton more efficient at 24 psi than my T76 was. That automatically translates to a cooler intake charge. Presently, my mixture is a tad richer than my target a/f which further translates to more intake cooling. I'm running the intercooler with ambient water. No icing (at present anyway). Again, cooler intake charge. Now pay attention... when the 91 did come up on boost and stabilize at 24 psi, the car was skating the track as it did when the T76 was on there at 30 psi boost.

So. My impression, so far, is that I made the same hp with a cooler intake charge at less boost as I did with the T76 at a higher boost. The only thing that I can think of that contributed to this is the lower intake charge due to the higher efficiency of the turbo sizing. I guess I haven't hit that 'too cool' point yet.
Although, making the same power at a lower boost is pretty cool.

Hmmm. I forgot about the less exhaust back pressure I'm getting now. I'll get that measurement for you guys.

 

[Alky V6]

I have never read about any cold limit for the intake charge of an alky engine. But,... there is a limit to how hot you want your intake charge with an alcohol engine. It has been documented that power is lost when the intake temp is above that limit. The intake charge temp is controlled by boost level and extra fueling.

The place where the mixture temperature becomes important is in the cylinder during compression and ignition. That's why you typically see high CRs with alky engines. It gets the mixture temp up during compression to vaporize the mix, prior to ignition.

That is the key! It's not what the intake charge temp is. It's not what the CR is. It's how well the mixture has vaporized at the time of ignition. In some cases, you don't want all the mix vaporized right at the point of ignition, you want some of the mix to vaporize during the combustion process to control combustion temp too. That is especially true when nitrous is involved.

The perfect setup would have all the fuel vaporized by the end of the combustion process.

This is starting to turn into an alky tuning thread, isn't it.

So how do you control the charge temp during compression and combustion? And do you really want the intake charge excessively warmed?

 

[Alky V6]

Richer alky mixtures contaminate the engine oil quicker.

The present intercooler is not causing a large restriction to spooling as I see it. As the car rolls out, it stays at 97 kPa for quite awhile before any boost starts to kick in. At that engine airflow I don't think the intercooler capacity is even a consideration. The slow boosting at that point is a function of engine rpm and exhaust flow volume and temp. What is needed is more exhaust flow, a tighter turbine housing, and/or a higher stall T/C. There is a limit to how much nitrous I can put to the engine. A 300hp shot is beyond that limit. 220hp is very safe. So, as far as the nitrous goes, it's somewhere between 220 and 280hp.

Another thing that shows me that the intercooler is not presenting a problem at my present level of tune is the point where the boost takes off like a rocket. When the map reaches 135 kPa, boost rise is steep. I don't think the engine airflow is out of the capacity of this intercooler at 135 kPa.