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juan ruiz's Avatar
 
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Boost and More Boost....

Question is......

As many of you know we are running 30 psi of boost, so my question is, what is holding us from running lets said 40 psi of boost ?

I keep seen more and more cars running some big boost numbers and I can help to wonder whats up with us ?

Anyone care to discuss this ?
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Old 11-03-2004, 02:55 AM
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It's mostly limited by head temps, compression ratio and fuel octane ratio.

Are you still running single plug ignition? Dual plugs would allow you to use more boost w/o knock.

How about heads? Are they flameringed?
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Old 11-03-2004, 03:13 AM
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Juan, I would be more interested in getting the weight down. You have plenty of power. Example; I know a guy that has 600 ponies in a car that weighs around 1700 lbs. His first pass was high tens on street tires and was very easy on first gear.
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Old 11-03-2004, 06:56 AM
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Beep can probably speak best on this, but isn't there a bunch of old information on water and ethanol injection to lower intake charge tempreatures which allow for significantly higher boost?

Are you still married to the stock CIS setup?
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Old 11-03-2004, 01:45 PM
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Some guys are using a/c systems tied to liquid intercoolers to lower intake charge temps.
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Old 11-03-2004, 02:26 PM
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Melted pistons and other broken parts; there's a material limit to MEP and cylinder temperatures. Eventually, one'll hit it. Mechanical refrigeration of the charge is only a limited duration solution unless there is an independent APU powering the A/C system. Jim
Old 11-03-2004, 03:27 PM
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True, thats why it is used for the dragstrip. I think the other method is ice.
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Old 11-03-2004, 03:35 PM
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Thanks for the responces,

I do however continue my search to this answer, I have ask a lot of people but yet I havent receive an honest answer why can we run this 40 psi of boost ?

We must remember that we are blasting for less than 6 sec as the low boost is set up to 22 psi, only on 3 er gear will the 40 psi will come in, so I find it hard to think that heat could be a problem for this spirit ride.

Are you still running single plug ignition? Dual plugs would allow you to use more boost w/o knock.

Yes single plug, and to be honest until today I dont buy into this twin plug, I think that in my case it could bring little benefit, for others maybe better fuel comsumtion etc.

How about heads? Are they flameringed?

Not only they are flameringed I am running a prototype exhaust insert to speed the velocity of the air out of the exhaust, but this are old new as I did this a long time ago.


I am home free with the intake temps as all the test I have done shows that our intercooler is very effective, I will (If I find a sponsor for it ) will install a Co2 Kit

And yes I plan to bring the weight down, I am trying our best to do all this with a 100% Street Stock trim

Maybe I will have to eat the bullet again and try for my self to see what happens
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Old 11-04-2004, 01:51 AM
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Well it's no rocket science. You can always screw that boost knob and see what happends.

According to Corky Bell's book, peak forces on pistons/rods during heavy boosting are still less severe than inertial forces during high revs.

Twin plug stuff is nothing "to buy into"...it just works. To put it this way: if you "lighten the fire from two ends" whole mixture goes boom faster, which means it spends more time pushing down on pistons. Only drawback on aircooled heads is that you loose some material in heads, which make them run little hotter.
If you run DTA then you already have coilpacks and no distributor, which makes it quite easy to install twin.plugging. All you need is to actually machine the heads and buy second row of coilpacks. I'm personally quite sceptic about importance of exhaust inserts though. I've never seen a turbo engine that likes more exhaust backpressure.


Second alternative is to use cooler/more high octane fuel. E85 (ethanol, not methanol) runs cooler, has 104 octane RON and gives roughly 20% more power. You'll need 50% more fuel flow though.

Third trick is to fabricate a small cage on the top of intercooler and pour lot's of dry-ice on it. It will work on short stints.

Fourth is water-injection to keep temps low (not needed with E85 as it burns colder).
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Old 11-04-2004, 02:48 AM
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Juan,
When you say "exhuast inserts" are you talking about "D" shaped ports?


-Chris
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Old 11-04-2004, 05:15 AM
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Juan, all factory race engines came twin plugged (excluding ones where the rules did not allow it). If its good enough for the 935, I'm sure its good enough for you.
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Old 11-04-2004, 07:54 AM
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When Juan says exhaust inserts this is not something to add backpressure. This insert actually increases the flow dramatically. How do I know? I have the inserts on my heads. The port work on Juans heads is out of this world. Juan as you know I had a nitrous/co2 cooler on my car. Nitrous drops the temps more than co2. The nitrous will actually freeze up on the intercooler. Just like when you run nitrous under a carb the plate will have ice under it. It is very expensive to run the nitrous on it. Bottom line is if your cooler is not very hot to the touch and the turbo is in its efficiency range you will gain very little on a drag car. A road race car can hit this to eliminate the heat soak, but we are only hitting it for a few seconds so this is minimal. The best way to reduce intake charge temps is water methanol injection. I have this for my car, and you can check it out if you like. As for the twin plug deal the 935's did not have the fuel injection and ignitions that are available today. The twinplug was used as a band aid for this. If a small block ford can make 2600hp with a single plug why do we need twin plug so badly at 400hp? You are not running a dome piston. I say crank up the boost and make sure the fuel is there so they can meet in the middle and work things out Job's 88 930 he tunes is still running 30 pounds of boost with a stock long block no head gaskets and never opened! It is in the tune. Keep pushing Juan I respect you a ton for this!

Eric Hood
Old 11-04-2004, 08:03 PM
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Is exactly what Eric explain. Thanks for that inf do.

beepbeep

Well it's no rocket science. You can always screw that boost knob and see what happends

No kidding so if is not rocket science why we dont have zillion people runing 30 + psi on 911s ? anyways I will take your advice, I have gone this far and I dont see a reason to stop now, I will run 40 psi very soon and I will have my own answers

I am not sure why the concern about the intake charges, but I know I am good on that dept, if I have any concerns it will have to be with things like, pulling the studs right out of the case, and things of that nature, But thanks anyways...
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Old 11-05-2004, 02:06 AM
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the value of the twin plug comes from the fact that the plugs are not placed in the correct/optimum location of the chamber. They are off to the side and not centered. A centered plug provides the least amount of distance required for the flame front to travel. I would suspect the motor you are referencing at 2000+ hp are 4 valves/cylinder with the plug centered...
Old 11-05-2004, 08:48 PM
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JUST DONT GO LEAN!

Woo . I would think twice about water injection with that kind of boost , when water turns to steam your compression ratio will jump for a fraction of a second. Alcohol injection may be a better way to go or a Co2 bar spraying on the intercooler. You may also want to pull out a few degrees of timing at the higher boost, and for sure use race gas+..

Just weld on the heads and point her toward the moon! Give em hell Juan!!
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Last edited by doozer; 11-06-2004 at 07:43 PM..
Old 11-06-2004, 07:38 PM
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