Advanced Engine Theory and Design

[SPEEDSTAR]

Praise the mighty piston and rod, brother. Pass the fries this way.

You bring up another interesting device. An anti-reversion device. The perfect place to put one is at the point where the exhaust pipe is stepped up, when using stepped primaries. That brings up another topic of discussion. Continuously tapered exhaust primaries. Yes, I have actually seen them. Very, very expensive. Stepped primaries are nothing more than an inexpensive way to simulate a tapered pipe.

And Stephen Stills sang, stick your foot init, put it to the floo oor

 

[robbyc]

lets try expanision chambers on a na engine ..............why is it so quite in here?

 

[Alky V6]

lets try expanision chambers on a na engine ..............why is it so quite in here?

Very good point. The exhaust piping I am using after the turbo is 5 inches. The turbine housing exit is only 3 inches. I use a carefully tapered section to adapt the two sizes. I believe it's 14 degrees included. The idea was to try and expand the gas volume as soon as possible after leaving the turbo without undue turbulence being created in the process.

How about a two stroke type reed valve in each intake runner.

 

[SPEEDSTAR]

My downpipe is 3 inch tapered to 4 inch, taper of around 10 degs. I am thinking of adding a twisted splitter to keep the velocity up, and adding some vacume to it should help also . This is on a 70 turbo. The inside of the intake housing is ported and polished, the inside of the exh housing is ported and polished and opened up some at the radial opening. Its a p-trim super flow .63 exh., Its fed by a two log TH set of headers coated with ultra hi-temp black. Bolted to fully ported GN1's on a 9-1 , 272 cu. I am trying to keep the velocity up in the header, while reducing back pressure,retain the quick responce of the p-trim, but with less restriction at the exh housing, and increase intake volume and flow speed, basically the baddest 70mm anywhere. It will have increased volume at the p-trim and increased volume right after. I will also taper out the housing just after the blades in the housing to ease the transition into the downpipe. The dia of the exh at the wheel will remain stock. The pinch point will be as short as possible.

Don, could splitters be used in larger volume headers

 

[robbyc]

het if you use reed vakves no need for intake valves and with that big popet out of the way .......mmmmmm what about those intake lobes

 

[Alky V6]

het if you use reed vakves no need for intake valves and with that big popet out of the way .......mmmmmm what about those intake lobes

The reed valve wouldn't be strong enough to take the pressure of compression and combustion. I was just thinking it would be a good way to control intake reversion problems with big cams.

 

[Alky V6]

My downpipe is 3 inch tapered to 4 inch, taper of around 10 degs. I am thinking of adding a twisted splitter to keep the velocity up, and adding some vacume to it should help also . This is on a 70 turbo. The inside of the intake housing is ported and polished, the inside of the exh housing is ported and polished and opened up some at the radial opening. Its a p-trim super flow .63 exh., Its fed by a two log TH set of headers coated with ultra hi-temp black. Bolted to fully ported GN1's on a 9-1 , 272 cu. I am trying to keep the velocity up in the header, while reducing back pressure,retain the quick responce of the p-trim, but with less restriction at the exh housing, and increase intake volume and flow speed, basically the baddest 70mm anywhere. It will have increased volume at the p-trim and increased volume right after. I will also taper out the housing just after the blades in the housing to ease the transition into the downpipe. The dia of the exh at the wheel will remain stock. The pinch point will be as short as possible.

Don, could splitters be used in larger volume headers

I'm impressed! You guys are coming up with some good stuff. A twisted splitter would be a great way to straighten the flow pattern leaving the turbine housing. The exhaust flow is twisting as it leaves the turbine housing and straightening it out would cause it to exit the piping quicker do to a more straight line path rather than twisting and becoming turbulent in the pipe. The problem is, the twist is in different directions at different times during the engines operation. The splitter would be an interference except under the engine operation parameter it is angled for. It would be a compromised situation.

Splitters down the middle of exhaust primaries at the curves are already being done and is a very good idea. The big question is how durable can they be in the intense exhaust temps of a turbocharged engine? What material to use? How thick? Would thermal coating work?

Speedstar, experience tells me dump the 70. You need something bigger. Your going to be pushing the 70 into the inefficiency zone.

Thanks for the interaction guys. This is great.

 

[UR50SLO]

Two things...:

One:
Did you know if you spray on "weld through primer" 3M or any other off-brand that it will keep the inside/ouside/headers/mild steel/down pipe,exhaust housing ect.. anything that see's heat from rusting? It does not dis-color or wear off. Once it has gotten hot it just stays and looks nice.
Scuff up your exhaust housing and tape off the rest of the turbo and no more rust... For good.
Works especialy well on new headers (take that black factory crap off with a scuff pad) and put on the Weld Through primer.

Ok.. now to the engine discussion.

Read this link from Popular Science and see what you think.
I did this to my Maxima heads when I had them off. I've yet to detonate the engine and it runs very smooth.
You can hold your hand on the downpipe at idle. It's just warm. As long as you'd like. It never gets hot. I'd like to see anyone do that to their GN down pipe.
Interesting info... I'll be doing this to my heads going on the Buick too!

Holy Grail...Cyl Head Modifacations.

~Scott

 

[ijames]

I wondered if anyone here had tried Singh's idea. Would be real interesting to try on a set of cheap unported stock heads. I'd even contribute a set of head gaskets if anyone wants to do the labor . Just need some before and after tuning and timeslip data.

 

[Alky V6]

That's amazing. So simple. I hope Singh gets something out of this.

I wonder if the NOX levels are higher, since so much more heat is concentrated during the main combustion event?

 

[SPEEDSTAR]

Once , a fair while ago, I teched post race protest at a local track. A kart in the WKA stock class spun during a race , and took off chasing down about 10 karts and went to the front and won. These engines are blueprinted stockers and real close in power. So during the teardown, by a protest , everything checked out perfect, except the carb bore had a spiral helical groove .070 wide, .030 deep cut the length of the bore. The cam, head, ports,fuel,crank, rod and piston,everything else,passed easily, What was the deal with the illegal carb, The guy ran em down quicker than was thought posible with just a groove in thecarb bore. I'm thinking a vortex was made in the bore , the type where the groove speeds up the hot air and pulls it outward , while the cold air stays in the center , the faster hot air puts a vacume on the volume of cold air, causing alot higher velocity and volume to fill the cyl.

 

[robbyc]

you know years ago smokey unick developed a hot air engine or as it is now called adiabatic engine this enging used extreem heat in the intake to superheat the air and gas to a plasma charge (there is that word again) the problem was that when it expanded from the extreme heat there were big reversion problems now this air fuel charge were heated to 440 degrees f so he had to use a check valve for his anti reversion device does any body know what this was....it was a turbo . well i know this info doesnt help us ...but if there was some way to keep that intake pressurized when the throttle shut....... but one way race engines do this is to have individual throttle plates close to the intake port and this takes care of many dynamics instead of it being a 6 cyl engine it is 6 single cyl engine that share a pressurized air supply throttle response ie great on an ir engine (individual runner) robby

 

[Alky V6]

Wow. My mind is busy trying to figure out where we could use this.

 

[Alky V6]

Interesting info... I'll be doing this to my heads going on the Buick too!

Holy Grail...Cyl Head Modifacations.

~Scott

Thanks for passing on the primer tech Scott.

Keep a watch out when doing the chamber mod on a stock Buick head. The deck surface of the heads are pretty thin to begin with.

 

[robbyc]

yes great tip about the primer it is some tough sruff i restored a porsche this year and welded in many panels and used many cans thank you for the tip robby

 

[The Swede]

The heads,

I think the ultimate heads to use should be hemi heads with twin sparkplugs and twin over head cams with a new intake design and bigger channels.

 

[UR50SLO]

Holy.. ..

I tried several times to get information on Mr. Singh and how to contact him on my success using his simple process to the combustion chamber of my Nissan heads. You should see the plugs that I pull out of the nissan.. They look like I've never put them in. Perfectly white. Which I'd see as lean or too hot of a heat range. I've tried colder plugs with the same result!
I did this to my boy's 2 stroke PW50 (little mini bike) Made a series of diamond cuts in the top of the head pointing toward the plug. Pop'd the head back on and took them for a few more trip's around the block. Pulled the plug and it's casper white. Weird!!!!
It must be the turbulance created when the piston is coming up forcing the air/fuel to swirl and mix. Sure works.
They don't have to be very deep.. I'll try it on my heads and post a pic.

I know we are all fuel injected here but back in my Small Block No2 days I'd take stainless steel screen (looks like regular screen door stuff) and sandwitch it between two holley gaskets with High temp RTV.
I'd place that under a 1/2 or 1" spacer (to clear the throttle blades) and i'd pick up 3-4 tenths. Brakes up the unatomized fuel droplets that can actually burn. It'd idle better and if you dropped somthing in the carb you can retreive it with ease. If your going to do that use a Stainless screen and a SPACER! Funny you mentioned Smoky Yunick.. I sent him one to try on a test engine back then.. didn't hear anything but it was cool to talk to a legend!!! Hell of a nice guy. Spent at least a hour talking about rod ratio fueling ect.. neat day in my life..

Weld through primer.. Another accidental find :biggrin:

Great Ideas guys.. let's keep think'n..

~Scott

 

[Alky V6]

An aquaintance of mine, Murl Bruton (The Wizard), who is no longer with us had the chance to meet Smokey Yunick. Smokey was out west and met Murl at his shop. Murl related to me what it was like to talk with him. My friend said, "He's no different than you and I." I took that to mean that he was a down to earth fello, a good ole boy that enjoyed talking cars and loved to tweak and tinker. I sure wish that I had known he was in town. I would have enjoyed meeting him.

About the screens under the carb. I recall seeing in a catalog, some intake gaskets that had screens built into them. It's the same idea that is used on everyones sink faucets. The screen diffuses the water flow causing a uniform flow pattern past the screen , while also aerating the water. I would just worry about sucking a screen. On my Alky ver. 1, I used a diffuser plate under the doghouse of a Bowling Green Customs intake manifold. It was an aluminum plate with very tightly spaced small holes drilled into it. A very course screen if you will. All holes were chamfered on both sides to help flow through the holes. It was very time consuming to make. A lot of holes. I wasn't able to tell if it helped, but I'm sure it didn't hurt. The engine performed as calculated it would.

About additives to methanol. I do plan on playing with the fuel after I get a good tuneup dialed in. It will be interesting to see some comparative results.

 

[robbyc]

i was lucky enough to meet smokey few years back i even have pics with him somewhere he was a man who wanted to talk more about the hijinks that went on at the tracks he went to with junior johnson more than the heady science stuff and i talked to him many times after that.i have never been one to hero worship but if there was ever one i would it was him .the day i heard of his passing hurt me deeply i have known quiet a few engine builders that really got into the science of it i have worked with eddie folwer gene fulton and known many more but none affected me the way he did he was way ahead of his time i have worked in nascar i work in the american lemans now we are involved in cutting edge stuff but nothing compares to the things i have seen at .....(the best damn garage in town)

 

[robbyc]

i built a homemade flow bench many moons ago and i used a light grid for a floresent light to act as a air straightner