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Supercharging

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Trick6

Trick6

Jedi Hopeful
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I am planning to build, on paper, two supercharger modification programs consecutively. I am doing this to identify and itemize each component and its cost. One program will be the multi port fuel injection and the other will be the single SU carburetor version. The multi port FI will require a lot more stuff.

My question is how come these after market carbureted supercharger magic kits allow the use of the hot air from the engine compartment, with a forward radiator air intake option, and all the DIY and production supercharger systems incorporate an external air intake plus the intercooler? Something is not right here and I have not started the research yet. When ever you compress air, you are heating it aren’t you? I believe you compress air, cool it, mix it and then inhale it. Not bring it in (hot or mild), mix it, compress it, and then inhale it. That is pushing in hot air directly from the compressor. That outside (cooler air) pick up is a waste of money with this system. I am sure that you are bringing in cooler air then the engine bay air, but you are heating it up again when compressing it.

Is there a system out there that is using the supercharger, carb(s) and an intercooler? I would like to see that.
 
Good point Al. Just the process of "supercharging" would also begin to super heat the air moving out of the compressor. What do the Benz and other "Kompressor" driven engines use for an air intake system?
 
Most car manufacturers use some sort of intercooling when going forced induction. It's a little harder with a positive displacement supercharger rather then a turbo, as throttled volume of air has to be considered. The supercharger on my Miata doesn't have an intercooler, but I'm only running 6 psi, so I can get away with it. Besides, my timing controller looks at incoming (through the air flow meter) air temp and will adjust the timing if needed. But, it is a problem and everything possible should be done to keep air temps down.
 
Thanks Tom. That's a pretty interesting article, spelled out like that.
 
As I understand it, the intercooler comes between the turbo and before the intake to cool the gas to get a more dense charge in the cylinders (cold air is denser than hot air)
I think it's more important on turbos (than blowers) because the air is already heated before compresion by proximity to the exhaust system that provides the turbo power. After the compression it's very hot leading to poor filling of the cylinders.
 
As for the cold air intake, ie external air intake, they do make a difference in that the air that you compress starts off at a lower temperature. So if you gain 70 degrees in compressing the air, it is better to add that to the ambient air (say 65 degrees) than the air inside the engine compartment, say 135 degrees.

This is regardless of inter cooling or any additional means of cooling the intake charge. Everything helps, inter cooling, cold air intake, water/meth injection, the atomization of fuel from a carburator, what the best bang for the buck is personal opinion and research.

Whatever you go with make sure to look at a thermal efficiency chart for the sweet spot of boost to tempurature increase.

Good luck
 
Tomshobby:
That is a great article. I have placed it in a folder for reference. I noticed that there was not one word about cooling. Going back to the good ole days, the blowers were placed right on an intake manifold between the carb(s) and the head. No cooler at all. The carb(s) was taking in fresh air, usually located above the hood.
AltaKnight:
Dick Taylor’s turbo with carb. https://www.turbo-tr6.info/overview_dt.htm
This car is a turbo with a “<span style="text-decoration: underline">suck through</span>” carb configuration. This setup’s air flows in from the fresh air pick up, ducted to the carb, the turbo sucks the mixed air/fuel from the carb, compresses it, and then pushes it into the motor. Instrumental to this system is “Water Injection.” This cools the compressed mixture before it enters the motor. I understand that the radial combustion engines on fighter aircraft of the forties used Water Injection for mixture cooling at additional boost levels for extra power. More research needed on the water injection topic.

I am wondering if there is a “<span style="text-decoration: underline">push through</span>” carb system. In this setup the fresh air is ducted to the supercharger, compressed and boost forced to the intercooler, then to the carbs and the motor. All under presure from the supercharger.
 
You might want to look at Corky Bell's book, Maximum Boost. It is a pretty good discussion of these topics. He wrote it mainly looking at turbo applications but all of the discussion of blow-thru vs. suck-thru, intercooling, throttled volume, etc. apply equally to both turbos and superchargers.

Bryan
 
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Instrumental to this system is “Water Injection.” This cools the compressed mixture before it enters the motor.[/QUOTE]

Isn't this the same as the fluid injection used on the aluminum block 215CI Olds F-85 JetFire engine in the early 60's? The best you could get with a 4bbl carb was 185HP, but with that system, it put out over 215HP. It stayed rated at 215HP due to the ban on engines putting out over 1HP per 1CI.

This is from the WIKI:

Turbo Jetfire

In 1962 and 1963 Oldsmobile built a turbocharged version of the 215. The small-diameter turbocharger was manufactured by Garrett AiResearch and produced a maximum of 5 lbf/in² (34 kPa) boost at 2200 rpm. The engine had 10.25:1 compression and a single-barrel carburetor. It was rated at 215 hp (160 kW) @ 4600 rpm and 300 lb·ft (406 N·m) @ 3200 rpm. The high compression ratio created a serious problem with spark knock on hard throttle applications, which led Olds to use a novel water-injection system that sprayed small amounts of distilled water and methyl alcohol (dubbed "Turbo-Rocket Fluid") into the combustion chambers to cool the intake charge. If the fluid reservoir was empty, a complex double-float and valve assembly in the Turbo-Rocket Fluid path would set a second butterfly (positioned between the throttle butterfly and the turbocharger) into the closed position, limiting the amount of boost pressure. Unfortunately, many customers did not keep the reservoir filled, or had mechanical problems with the turbocharger plumbing.

The turbocharger was offered only in a special Jetfire model, which was the first turbocharged passenger car offered for public sale. Only 9,607 were sold in two model years, and many were converted by dealers to conventional four-barrel carbureted form.
 
Hi Al,

The newer roots type blowers are more efficient which helps lower heating the charge & use lower boost. The M62 unit is rated for 2.5-4.0 liter motors. Although it was & is still used on carburetored engines, Eaton frowns on wet (fuel through the blower) system & I'm not sure they warranty them in this application any more.

In the case of the '6' engine bay & fender wells do not allow for an intercooler if mounted dirrectly to the manifold. Most of the manufacturers who use the M series SC (Mercedes, Saturn, GM) on factory production cars do not incorporate inter coolers. I have never done any testing so I can not say what performance gains (if any) there are to be gained.

I'm not comfortable with sucking in engine bay air either but making a cold air intake is a simple project that can certainly take advantage of colder front end air to cool the charge. I definetly feel performance gains on a cool fall evening than on a hot 90 deg summer day, but any forced induction motor or NA motor for that matter will do better with denser/cooler air.

You can bolt on a carbuerated sytem in a weekend & start having fun, certainly FI is more complicated & expensive. The end results in HP and performance are minimal. If the challange & desire are there to SC & FI , then I say go for it. Do what you enjoy.
 
If you're looking at the M62, take a look at the opcons that Whipple are now selling (they bought opcon). Roughly the same size and way more efficient. The AX140 is about the right size for the car.
 
Mitch:
Man do I have questions. Who's kit are you using? When did you get it? What fuel pressure are you running? How difficult was it to get the carb mixture correct? Are you using an AFR meter? I wonder if my GP2 cam will work; I do not have cam bearings so I am stuck with mild cams. What size cc is your head or CR? I see that you are using MSD components. What timing settings (I don’t see a vac line to your dizzy)? Any problems with detonation? Have you had the monster on the dyno yet? I wish to know what to expect in performance gains. I am putting out 118 HP at the rear wheels now.

There will be more.
 
Gee Al, I was hoping that you really had another life on a Saturday night, not like us die hards. I'm an old fart, but you're a young handsome guy with a shiny red sports car. I thought you'd be out cruising tonight for sure.
 
Al,

if you're going to be supercharging your ride, then you don't want a radical cam. The GP2 might be as much as I would do. Also, you don't want to mess with the compression either. Maybe get some late style heads to lower it a bit; this will allow you to run more boost. You want to figure out a way to get the coldest air possible to that blower intake. This makes for a denser charge and results in more HP.

Your worst enemies here will be compression, the strength of bottom end of the engine (which isn't very strong to begin with), and proper air fuel ratio; you might consider fuel injection. It's really the only way to do it properly. Carbs can't be tuned to keep optimum air/fuel, so you are forced to run it too rich for safety. A FI system can run much leaner and thus make more power.

All this being said, I wouldn't even touch a boosted mill without a rebuild.

A few years back I had a 2000 Mustang with a Paxton blower on it hitting 394hp to the wheels... that thing was insane.

Just remember: The leaner the meaner...until it blows. :smile:
 
That's why I posted the Olds info. They had all kinds of issues because of the high compression and gas was really high octane back then. Those engines did not have exotic cams in them either.
 
I will attempt to respond to you all.
1st Alan:
Great reference to the Whipple people. It sounds like they maybe the best at what they do. You must have talked to them so how much for that 140ax number.

Now Paul:
The wife and I played golf today. We walked all 18 holes. I got home, sipped on a tall Crown Royal straight up, took a shower, ate a little something, thought about a short cruise and could not move. Decided to come up and do the BCF thing. Wanted to go see The Dark Knight but could not move.

Shannon:
All good advice. The motor is fresh. The bottom end is balanced and "squared." Everything but CAM BEARINGS. %$#@. See the link below for my motor program. I have another head and intake which I can have some things done to. Get it to about 8.5 CR. Think I am going to build on paper a phasing program where I can start with the carb/suck thru setup and then graduate to the FI later, that is if I like it. I have not ruled out the little Ecotec conversion. One of those little beauties will cost less than the head work SC/FI fit out and produce more HP. They are lighter, stronger in the bottom end, come with the SC and no guess work. That is the reason for building on paper. No Cost.

What did I misspell?
 
No misspelling!

I played 18 and rode, but after a rotten 4 day cold, I couldn't move either and I didn't have any CR. Closest I came to that was a Coke with a burger that I made on the grille tonight.

Best to do it on paper first. No hurt then if a new idea comes up along the way.
 
Hey Al, Love your enthusiasm !!

I will preface the following by stating what I have done & learned about supercharging started without any real understanding or training other than years of mechanical toying with sports cars. I know my system well & have played with the idea of FI but I keep coming back to "why", don't fix what ain't broken. I am not saying to anyone who either has a project in mind or is in the middle of one that it's not worth it, all I'm saying is, sometimes simplicity works.

The current motor is in the car for five years. The entire block & all rotating parts were gone through & balanced. Tolerances were kept on the tight side. I'm using the original con rods & crank, these have never been a problem on either motor. I took short cuts with my first machine shop & paid the price. The price was pulling the engine a year later (actually then 6 years ago) and starting from scratch. The tear down exposed broken rings & worn ring lands. I did not change the pistons on that rebuild, the current motor used new stock Hepolites .030 over. The rods were gone over smoothed but nothing radical. I have a friend in CA running a turbo's motor using several lbs more boost than me with stock rods & pistons pounding out well over one hundred thousand miles between rebuilds.

I sourced a cam from Integral cam. Steve, the owner talked over the needs and cam up with a cam similar to a GP2 but with a shorter overlap, 113 deg, to contain the charge. SC's engined overcome many design short comings of the TR motor. Certainly the head is not going to win any design awards, but when your forcing the air/fuel in you can work around poor flow & chamber design. Certainly improving what you can would be beneficial. The rest of the motor is mostly stock other than larger exhaust valves, headers, alum flywheel, MSD w/boost retard. After I the break-in I increased the boost to 9lbs. The car has been incredibly reliable, ALWAYS starting on the first crank, summer or winter & idling better than stock.

There have been allot of mods over the years to improve air flow, ignition & exhaust. These have been my real tuning benefits for the motor.

I'll chime back in tonight with some more details if you need, I'm being summoned by my family for lunch. TTYL
 
Mitch:
More details please. Is this a B. French unit? Since you have owned it, what would you do differently? What DON’T you like? Who do you rely on for ongoing communication? Are you running an AFR monitor? I will need to know about the boost retard workings of the MSD. I can research that. Is there something you can refer me to for reading material paper or electronic that is simple. I know this is a simple operation; I just want to know the back stage stuff. Have you dyno’ed the car? What fuel pressure does the system like?

I agree that a huge single throat carb in front of a SC is a very simple and manageable large hp producing modification. I am liking this. Now, if I am putting out $3,000, I would like to get a $3,000 kick in the ass when done. What “boost” in performance should be expected?

I will have more questions. We may need to do a side bar (Private Message). But for now, this is info to be shared with all.
 
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