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Old 11-19-2003, 06:01 PM   #16
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Quote:
Originally posted by Motorman

I've been keeping my mouth shut for a long while but I have to say somthing.
TG you need to let go of the marine mentality man. If it works for you great but I know I can make more power than you on 30% at .018 and 40% at .021 with zero detonation at 4.5 mm exhaust height. we do it every day no problems. What you shouldn't be doing is spinning people off towards unrealistic head clerance on their production motors. If its a hand built thats a different story but you do them a disservice by directing then toward toward a global meltdown of their hardware.

If you feel inclined to take .008 thousanths head clerance advice do so at your own risk that is all I have to say.
Thanks a lot for your input.
Motorman, you know, I made strong respond, but decided to edit it. We will see who is right!!!!!!!!!!
but your post is very promissing to me, I love it. It means, I am on right way even from your point of view!!!!!!!!!!!
4.5mm-154.41 degreese 164 degreese is better!
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Last edited by Top Gun 777; 11-19-2003 at 07:50 PM.
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Old 11-19-2003, 06:14 PM   #17
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Quote:
Originally posted by Top Gun 777
Thanks a lot for your imput.
Motorman, you know I made strong respond, but decided to edit it. We will see who is right!!!!!!!!!!
but your post is very promissing to me, I love it. It means, I am on right way even from your point of view!!!!!!!!!!!
Hey TG

Just take it easy, things is going good.
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Old 11-19-2003, 06:23 PM   #18
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Default Re: Re: Engine Shim Tuning

Quote:
Originally posted by Corse-R
You can go down up to .021" with a 30%, but plug selection will be critical (you're on the ragged edge for 30% Nitro). Better to go with a Nova 7Tf with those nitro percentages. You can go down up to .018, but will be quite risky and will be quite weather sensitive.
Corse,

I usually run my NR based engines with 0,3 mm shims, 30% nitro and the shortbody 5TF plug without the slightest problems.

That is in Georgia weather where the temperatures reach 100F with 95% humidity.

Never had detonations or premature wear on my engines.
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Old 11-19-2003, 09:52 PM   #19
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Quote:
4.5mm-154.41 degreese 164 degreese is better!
and Illegal too.
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Old 11-19-2003, 10:02 PM   #20
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Whats the use TG if you can't race it in a real event?
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Old 11-19-2003, 10:49 PM   #21
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Thanks for the advice. The engine is the USA ver with a normal head and 3 ports. I run with 16% nitro. the head has 2 copper shims at 0.004 each so removing these will give me 0.020, which might be ok.

I have just receved the turbo button for the pixy and plann to put this in. What plug should I use?

Chees
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Old 11-19-2003, 10:54 PM   #22
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step up to 30% fuel it will help you and the engine will run better at .020 head clerance. I would use a 5tf like was recommended on the 12's you need a hot turbo plug. In my opinion the 5 is just barely hot enough.
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Old 11-19-2003, 10:58 PM   #23
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Motorman. Whats CR when you say "The CR is too low"?
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Old 11-19-2003, 11:28 PM   #24
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His engine might leak or not seal up right if he takes all of his head shims off to get it down to .020". Or is there not a problem with not using any shims as long everything else is good to go?
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Old 11-19-2003, 11:33 PM   #25
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it might if the machining is not smooth enough. he will have to try it. I turned my head button down on a lathe so I could still use one. its not a problem if it don't leak
I guess I should be saying TCR
TCR=Compression ratio=trapped compression ratio
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Old 11-20-2003, 08:09 AM   #26
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Quote:
Originally posted by Motorman
and Illegal too.
No, you wrong, it is totaly legal! read the roar ruls!
There is nothing about timing!!!!!!!!!!!
Just to give you an idea how it can be done one of the way. If you make conrod lenght not 25 mm, make 17 mm you timing will be 164 degree. It is just one of the way to do higher timing on exhaust and styas within ruls. Marine mentality!!!!!!!!!!
Just don't look on issue ordinary, be creative!!!!!!!!!!!
I have offered my help, but was regreted. I can be very helpfull with my marine mentality. I want to be very helpfull for everybody! I want to share my ideas and expirience!
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Last edited by Top Gun 777; 11-20-2003 at 09:10 AM.
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Old 11-20-2003, 08:11 AM   #27
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Quote:
Originally posted by sparksy
Whats the use TG if you can't race it in a real event?
It is totaly legal and can be use on any sanctioned event ( ROAR, EFRA, IFMAR etc).
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Last edited by Top Gun 777; 11-20-2003 at 09:55 AM.
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Old 11-20-2003, 09:28 AM   #28
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Quote:
Originally posted by Top Gun 777

Just to give you an idea how it can be done one of the way. If you make conrod lenght not 25 mm, make 17 mm you timing will be 164 degree.
Ok, from what I know about Engines. Displacement and timing are basicly what determine HP. Stroke effects the powerband.

If you shorten the stroke, then restore the CR. Won't this create an Engine with a even narrower powerband? Wouldn't that counter any gains from the timing change?

Just curious?
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Old 11-20-2003, 09:34 AM   #29
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Quote:
Originally posted by popsracer
Ok, from what I know about Engines. Displacement and timing are basicly what determine HP. Stroke effects the powerband.

If you shorten the stroke, then restore the CR. Won't this create an Engine with a even narrower powerband? Wouldn't that counter any gains from the timing change?

Just curious?
I didn't talk about the strok, I was talking about conrod lenght. On Novas based engines it is curently 25 mm between centers of the holes. If we make conrod lenght 17 mm, it will give us 163.5 degree timing duration on exhaust without changing anything else. It is just one of the way to work this issue out. there are much more, not ordinary but very interesting solutions.
Just we need to be creative and use non common sence.
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Old 11-20-2003, 01:16 PM   #30
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Quote:
Originally posted by Top Gun 777
No, you wrong, it is totaly legal! read the roar ruls!
There is nothing about timing!!!!!!!!!!!
Just to give you an idea how it can be done one of the way. If you make conrod lenght not 25 mm, make 17 mm you timing will be 164 degree. It is just one of the way to do higher timing on exhaust and styas within ruls. Marine mentality!!!!!!!!!!
Just don't look on issue ordinary, be creative!!!!!!!!!!!
I have offered my help, but was regreted. I can be very helpfull with my marine mentality. I want to be very helpfull for everybody! I want to share my ideas and expirience!
Let's see if we can shed more light on your comments.

Transfer height (linear measurement) determines timing on a 360 degree wheel. 164 degrees of total timing for the exhaust port determines a height on the exhaust port. If is ROAR legal or not is an issue that should not bother anything. When your engine is teched, the exhaust transfer height is measured on milimeters, not timing degrees and if is higher than 4.5mm, you're deemed illegal and you're out of race.

Reducing on 7mm the conrod lenght is a no no. Shortening the conrod makes to collide the piston skirt with the counterweight of the crankshaft and you need to remove more material from the piston (still, doubt if current pistons can accept to radical material remove) this piston will be weakened up to a point that will be unstable into the sleeve and will rock into the sleeve, scratching it and making it ovalized.

Marine mentality is fine for boats that only rely on high rpms to produce power not for cars that run on a closed track (probably are fine for tether cars or planes too), hence here their exagerated exhaust timings along to ultra-high compression ratios (or ultra small combustion chamber heights - name it as you prefeer) that rely on the extreme timing to control what occurs into the combustion chamber. As a plus, those engines run with a water cooling system, so their temperature never reaches the extreme temperatures you can find in a .12 engine with a closed body.

Edward, probably this is your worst problem, you're directly extrapolating what works on boats to cars, and this doesn't work on all cases. Some of your ideas are interesting, others don't apply, others simply... well.

Here, many people works and make 1:1 engines for a living (Engineers, motor builders, mechanics), others simply are gearheads (like me, have their own experience building their own engines, but their money is earned in other places), other simply rely on the experience of other people because they don't want headaches with engines.

Some of your advices aren't questionable are directly dangerous and harmful to people with light or no knowledge of our engines (0.008" of chamber height is a fine example, another is to make propaganda that for making power, the best is to reduce Nitro on their fuel).

If you're right, all the guys that run on Funny cars or other Top fuel categories are doing a complete nonsense burning a mixture of 90% nitro and 10% of Methanol, running 100% Methanol is much cheaper to run their multi hundred thousands cars burning thousands of dollars on each weekend they run.

On this last assumption, you're extrapolating what happens on FAI categories that are limited by rulebook to low or no Nitro percentage on their fuels to car engines, who can run and are designed from the ground for the use with fuels with Nitro (trying to carb an engine running with no Nitro is a bitch to do...).

Nitro is vital and necessary for the chemical process that happens into the combustion chamber one of their actions is to give Oxygen and Hidrogen during the combustion, other less known is to slow the flame speed of the methanol burning, needed to control the explossion on the combustion chamber and help to give more power making the burning of the fuel and the explossion longer in time hence producing more overall power.
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