I have some spare parts laying around and was thinking they might make a good engine

Re: I have some spare parts laying around and was thinking they might make a good eng

Dam Sean,I wish we lived closer to each other,I would love to help you get that thing going.


Derek

 

Re: I have some spare parts laying around and was thinking they might make a good eng

The fuel octane to be used would be highly dependent on how cooled the air could get before going into the combustion chamber. I don't have a formula for this, I'm more of a N/A guy, though forced induction is certainly fascinating.

I'm sure there will be others who may chime in who know how to sort it out.

I'm also pretty sure there's a formula out there that translates air temperature to DCR ratios and which octane fuel would be required.


Gary

 

Re: I have some spare parts laying around and was thinking they might make a good eng

Its either going to work or ain't. So might as well go for 35 psi.

Derek

 

Re: I have some spare parts laying around and was thinking they might make a good eng

I will not be a rush to get this together... I need to focus on getting the fuel system built for the car and getting the good engine in the car. I am finding the garage really cold as it is not heated so I have got very little work done this winter. This summer I will get a natural gas heater setup into the garage and I can get more work done...

My current project is fitting a big capacity electric fuel pump into the stock tank. I found a pump small enough to fit into the hole at the top of the tank and attach to a Rob MC fuel pickup. This way the pump is submerged in the fuel tank and it can just push instead of pulling fuel up out of the tank. I have 30 feet of 1/2" inside diameter stainless tubing but I may buy flexible fuel line instead to save time. I got the stainless tubing for free from work so it is not a big deal if I don't use it. Either way I need 1/2" for both supply and return.

I noticed that the pickup I got in the mail has an extra 90 degree turn at the bottom, which looks better than the ones shown on his website.

 

Re: I have some spare parts laying around and was thinking they might make a good eng

No one is rushing you,I for one know how hard it is to work with no heat. It doesn't matter how much anyone can handle being out in the cold when it comes to working with your hands.

When you can make your tongue stick to your tools(LOL)you shouldn't be handling them without gloves,and I for one can't work with my hands with heavy gloves on,that's why I shut down my un-heated garage in the winter.

It's winter right now,so its mostly about discussing about what will happen when the weather co-operates,unless your from the always warm region.(hate those guys! they're cool though)


Derek

 

Re: I have some spare parts laying around and was thinking they might make a good eng

Hi Gary,

I have heard of 12:1 engines that are running big boost but it I bet the tuning window is much more narrow than running 8:1...

A lot of it depends on the engine design I think. Another factor is the expected life expectancy. To run for 20 runs and then rebuild sure running high compression with high boost is fine...

Overall if I were to put my 9:1 engine against this theoretical 7.5:1 engine I would put money on the low comp engine making more power being able to handle more boost. Not all engine designs will react the same either so a lot of this is experimental.

I know no one is rushing me, I just need to get one thing done at a time and keep myself from getting side tracked... I get way less done due to the cold shop, I can get work done but I enjoy it less... After the car is together I will look further into building this engine. At least I know that the parts should be able to work together for a low compression super strong build.

My plan would be to take a 68 block, smooth out a crank and get rid of any sharp edges, have the rotating assembly internally balanced so I could use my SFI balancer and flexplate, do a partial epoxy fill on the block, have the block and caps machined for a girdle, and mill the deck to get the compression I want.

It sure would make a strong engine for boost

I will copy and past some interesting info I was reading:

People have tested the power effects of raising compression for decades, and the most optimistic results are about 3% more power with an additional point of compression (going from 9:1 to 10:1, for example). All combinations will be limited by detonation at some boost and timing threshold, regardless of the fuel used. The decrease in compression allows you to run more boost, which introduces more oxygen into the cylinder. Raising the boost from 14psi to 15psi (just a 1psi increase) adds an additional 3.4% of oxygen. So right there, you are already past the break-even mark of losing a point of compression. And obviously, lowering the compression a full point allows you to run much more than 1 additional psi of boost. In other words, you always pick up more power by adding boost and lowering compression, because power potential is based primarily on your ability to burn fuel, and that is directly proportional to the amount of oxygen that you have in the cylinder. Raising compression doesn't change the amount of oxygen/fuel in the cylinder; it just squeezes it a bit more.

So the big question becomes, how much boost do we gain for X amount of compression? The best method we have found is to calculate the effective compression ratio (ECR) with boost. The problem is that most people use an incorrect formula that says that 14.7psi of boost on a 8.5:1 motor is a 17:1 ECR. So how in the world do people get away with this combination on pump gas? You can't even idle down the street on pump gas on a true 17:1 compression motor. Here's the real formula to use:

sqrt((boost+14.7)/14.7) * CR = ECR

sqrt = square root

boost = psi of boost

CR = static compression ratio of the motor

ECR = effective compression ratio

So our above example gives an ECR of 12.0:1. This makes perfect sense, because 12:1 is considered to be the max safe limit with aluminum heads on pump gas, and 15psi is about as much boost as you can safely run before you at least start losing a significant amount of timing to knock. Of course every motor is different, and no formula is going to be perfect for all combinations, but this one is vastly better than the standard formula (which leaves out the square root).

So now we can target a certain ECR, say 12.0:1. We see that at 8.5:1 CR we can run 14.7psi of boost. But at 7.5:1 we can run 23psi of boost (and still maintain the 12.0:1 ECR). We only gave up 1 point of compression (3% max power) and yet we gained 28% more oxygen (28% more power potential). Suddenly it's quite obvious why top fuel is running 5:1 compression, that's where all the power is!!

 

Re: I have some spare parts laying around and was thinking they might make a good eng

The actual issue is the final temperature of the air/fuel charge at the end of the compression stroke and whether or not it reaches the point of auto ignition after ignition begins.

The 2 main factors are the initial temperature as piston begins compression and the heat rise due to dynamic compression.
So if you can get the air/fuel charge back down to ambient temperature before it enters the cylinder then the compression ratio can be high again.
Then the limiting compression ratio factor becomes the pressure limit of the cylinder, pistons, rods, ect.. rather than detonation.

So you must look at the dynamic compression ratio along with the amount of intercooling versus the turbo outlet temp.

We used a BIG ice water intercooler.
Our turbo gas engine was 9:1 SCR with 25 psi of boost.
Our turbo methanol engine was 10:1 SCR with 35 psi of boost.

The turbo outlet temp at 25 psi of boost was around 300* F but the intake manifold temp was just over 100* F
At 35 psi of boost outlet temp was around 400*F and the intake manifold temp never got over 70*F because of the intercooler and the massive amounts of methanol being injected.

Problems with cylinder head sealing:

We were using a 430cid SBF which only has 4 head bolts per cylinder much like the Buick.
At 25 lbs of boost the head would lift. We would do a cylinder leak down test and see air bubbles in the radiator.
Pull the head and reseal, check the leakdown, ok, go make another pass and bubbles in the radiator again.

We decided to run methanol to get rid of the cooling system and run a completely filled block and solid billet heads.
We also had the top of the cylinder bores machined for nitrogen filled rings that would expand as the heads moved upward under boost.
Never had a problem afterwards.

On another methanol injected turbo engine that had six head bolts per cylinder, we used a solid block and ran water through the cylinder heads with a tiny radiator.

Solid filled block with water in the heads, methanol and no intercooler might be a good combination for a SBB.

Just my 2 cents worth.

Paul

 

Re: I have some spare parts laying around and was thinking they might make a good eng

Thanks Paul, all very useful info!

 

Re: I have some spare parts laying around and was thinking they might make a good eng

I was sorta hoping Paul would chime in on this thread...

He agrees with me that the temperature is the key issue, it's figuring out a ratio or formula maybe to find out the relationship between the dynamic compression and the effective boosted compression and the ambiant temperature the air can be in relation to these two.

I understand it's an experimental thing, but surely someone's come up with something (turbo engines aren't exactly new technology). Or maybe I could, if I had sufficient data to compare. I dunno.

Lots of other things affect the dynamics of forced induction airflow as well, such as cam overlap and how much pressure is released into the exhaust system, the speed at which the air enters the combustion chamber (does the volume have more or less velocity to achieve the desired PSI?), and more will all affect air temperature and the ultimate result at the end of the compression stroke as to whether or not detonation will occur.


Gary

---------- Post added at 11:13 AM ---------- Previous post was at 10:59 AM ----------

Ultimately, the cooler the better, obviously.

 

Re: I have some spare parts laying around and was thinking they might make a good eng

One of the reasons I made the good engine 9:1 is so that a ton of boost was not required to make decent power... More boost means more need for intercooling. Where as with relatively low boost a simple water/ methanol sprayed into the air before it gets to the carb is all that is needed and this keeps the boosted air plumbing short and direct.

I looked into water to air intercooling as it is the most efficient form of cooling the charge however it is complicated and extra weight and space... For really high boost applications it is the best form of intercooling especially for a vehicle that is not driven at high speeds for long distances which is where the air to air intercooler shines.

 

Re: I have some spare parts laying around and was thinking they might make a good eng

And thats why scuba air tank forced induction is the most efficient. With a tank that has is holding say 2,000 psi and you release pressure of 20 psi the air that is releast is super cooled and would cut down the detonation factor significantly.

This kind of forced induction was outlawed by the NHRA in the 70s because of all the whiners that were using a blower that took roughly 350 HP to run. With a scuba tank forced induction system the weight disadvantage was easily overcome by not taking 350 HP to make it work.plus no kind of intercooler was needed because of the very cool air charge that came from this sort of system. Not to mention much higher compression ratios that could be ran with this system.

The disadvantage to running this on the street is the limited amout of air that the tanks can hold,but would be great at the strip!


Derek

 

Re: I have some spare parts laying around and was thinking they might make a good eng

If you get a chance to go to the Don Garlits museum in Ocala Florida you will see this same thing on one of his TF dragsters.
The tank is most of the length of the front of the chassis with a large tube and a large air regulator that simply goes to the intake manifold of the engine. It doesn't say how successful it was and the 2 times I've been at the museum Don wasn't there to ask.

Paul

 

Re: I have some spare parts laying around and was thinking they might make a good eng

9:1 compression seems to be a standard for racing turbocharged gas engines.
As the boost gets higher, the intercoolers get larger and the fuel octane increases with additives that control combustion under boosted conditions.
We had a chest freezer in the trailer full of ice cubes just for the intercooler.
The gas was VP C16.
As Sean stated this type of set-up is only good for short periods of boost as in drag racing.

The air to air intercooler works far better than a water/air intercooler where boost is present for long periods of time.

The air to air intercooler also makes more power than the water/methanol injection.

The water/methanol works in stages.

Methanol has a lower point of vaporization so it changes state to vapor early, cooling the air along the way plus it has the side benefit of being a fuel

Water has a lot higher point of vaporization plus it take a lot more thermal energy to make it change state into vapor so it vaporizes in the cylinder during compression and does a great job of reducing cylinder temperature before and during ignition.

Reducing cylinder temps will help prevent detonation but if the cylinder temps and the heat of combustion are reduced beyond what is necessary to prevent detonation then heat energy is lost for the power stroke and engine power is reduced.

Also water is not a fuel and introducing it into the system displaces oxygen needed to make power.
It is the same effect as low engine power during very humid days.

I know it's a lot more work but a large non restrictive air to air intercooler is the way to go IMO.

Paul

 

Re: I have some spare parts laying around and was thinking they might make a good eng

Thanks Paul,

I am going to start out with the water/meth injection and if I want to crank things up into really high boost then I will setup some plumbing for the massive intercooler that I posted a pic of last page. This air to air intercooler was used in a Buick regal with a twin turbo v8 built by Ken Duttweiler. The intercooler helped the car make 1300 HP at the wheels so the intercooler would not be a restriction on my car.

 

Re: I have some spare parts laying around and was thinking they might make a good eng

(QUOTE) looked into water to air intercooling as it is the most efficient form of cooling the charge however it is complicated and extra weight and space... For really high boost applications it is the best form of intercooling especially for a vehicle that is not driven at high speeds for long distances which is where the air to air intercooler shines.

Sean, in the early 70's I was involved with a twin turbo 455 Olds powered modified tractor for tractor pulling that ran two air-research turbos and Methanol was the fuel we used. It dynoed 1,340 hp. We made our own primative wastegates and used a primative water/methanol injection that we made using a windshield wiper pump from a Plymouth. We afixed the washer nozzles to the rear of the modified quadrajet (methanol fuel required nearly 3-1 vs gasoline). When the boost reached 13 pounds it would kick a the windshield washer pump on and it would spray the methanol/water mixture into the back barrels of the quadrajet. Kept us from melting pistons but we were only blasting down a 300 ft. track. We were the first modified tractor in the northeast Ohio area to run turbo chargers. Everyone else if they weren't naturally aspirated were running 871 and 1271 Huffers. There was a learning curve too. We broke a lot of stuff figuring out how much boost that Olds could take and live. We o-ringed the heads and still blew a chunk right out of the side of the head one night. Sorry just reminicing and rambling here.

 

Re: I have some spare parts laying around and was thinking they might make a good eng

Thanks David, I would love to see some pics of video of that 455! It must have been a lot of fun to push the limits and do something different!

This is the water/meth injection I am using... It is boost referenced and adjustable.

http://www.snowperformance.net/stage-2-boost-cooler.html

I am not looking to try max boost on any of my engines except possibly this one made from spare parts and with low compression. I have a bunch of spare engines here and some of them are ready to run to make for quick change outs if needed...

My goal is to run fast and stay reliable, much like Jay3000 did over the past few years. He was running a really mild setup that made about 300 HP NA and 550 HP with turbos... He had plenty of fun with the car and lots of burnt rubber, and it sounds like the new owner is having fun with it too.

 

Re: I have some spare parts laying around and was thinking they might make a good eng

Re-visiting this idea! I wonder how much a person could mill off the deck of the block?

 

Re: I have some spare parts laying around and was thinking they might make a good eng

Personally I would look at longer rods or possibly ford 3.8 supercharger pistons at 1.600 and a.912 pin. Could bush rods for that pin .use the flat out gaskets at .050. And try for 9 to 1 then run E85. Runs cooler so you won't need as much intercooler.

 

Re: I have some spare parts laying around and was thinking they might make a good eng

The awesome thing about the pistons with a .912" pin is if you want to use a rod with a .927"pin hole in it the piston pin holes can be honed out to the .927" pin size and even if they are floaters the snap rings or whatever retainer that is used will still work. At .013" it needs to be bigger, it is only .0065" per side of material that is removed, but would need to buy the .927" pins if they can't be substituted when the pistons are purchased.(I would ask to swap wrist pins when I was buying pistons)GL

An Sean, you might be able to get away with milling off .100" off the deck for a low performance build.


Derek

 

Re: I have some spare parts laying around and was thinking they might make a good eng

Good idea guys, these are closer to what I need:

http://www.summitracing.com/int/parts/wis-5113a2/overview/