does anyone have any advice about building a hc motor? what kinds of things can be done to the crank to strengthen it, and do you know where it can be done. any advice would be greatly loved crutan
#66338, "RE: high comp motors" In response to Reply # 0
Since you are new, I will consider this my one no0b question of the day that I also actually answer the question before I refrence the search.
You can raise compression by milling the head (requires adjustable cam gears to take up slack in the timing belt or the right way, which is to buy a high compression rebuild kit. Stock CR is 9.6:1, you can pick up 8.8:1 (lower CR for high boost turbo applications), 10.5:1 (which I run with no trouble at all), 11.5:1 (might be someone here running this CR) or 12.5:1 which is possible to run on the street, but will require an enormous amount of supporting mods and attention to be streetable and even then, isn't a widely suggested route to take unless the car is a track only racer.
The stock crank could benefit from a decent balancing, but it's only really needed if you plan on building a race motor. Our cranks are pretty damn stout. I doubt they will have any trouble handling the amounts of power you throw at it. If you plan on realistically making over 300 hp with your motor or running an 8000rpm redline, you might want to consider it. The damn crank weighs almost as much as the block. Serious hardware man.
So now that I've answered this question, try using the search if you have questions about some of the things mentioned in here. There is so much info if you get into the advanced search. Welcome to the board sir.
#66344, "RE: high comp motors" In response to Reply # 1
Originally posted by DR1665 ...The damn crank weighs almost as much as the block. Serious hardware man. So now that I've answered this question, try using the search if you have questions about some of the things mentioned in here. There is so much info if you get into the advanced search. Welcome to the board sir.
A bare block ya, my crank was just over 33lbs on my scale. Up until a month ago I was running high compression. You can do 12.5:1 with timing control like an MSD DIS4. You can do 11.5:1 without any timing pulled on 91 octane and 7* on 12.5:1 (that's what I did safely with my plethora of setups. NA what you want is more CR and less timing. You will also need the Super AFC
*Skrilla "Honest officer, I thought you were trying to race me" Talon: 1st 2.4L '97 Prelude '04 350Z
Originally posted by YourInMyMirror95GS dick teaser's should be rounded up and shot in the forehead
Originally posted by etx Good luck man! Project 'STFU Brian your talon is dead meat' should be on it's feet soon!
Originally posted by Dark0ne Thanks. Now excuse me while i fuck your sister.
#66375, "RE: high comp motors" In response to Reply # 2
Brian, please don't use the word slack when talking about milling a head, timing belt geometry changes. The use of the word slack to refer to this makes me shutter.
The question is so broad. You can talk about just the building process, camshaft selection, brands to use, brands to stay away from.
So a broad answer, 10.5:1 is a mild upgrade worth about 4% increase in power. You get about 4% for every compression point you raise. If you want some more beef run higher, get 12.5:1 with some timing control, or go with custom 11.5:1 pistons (not a normal stock item), which is the compression I'll be using on my engine when I build it.
Make sure you take care of your intake and exhaust so the engine can flow well. Cams and porting on the head is always nice too.
#66379, "RE: high comp motors" In response to Reply # 3
i'm now confused....
one thing that was not addressed was timing gears....
lets say one was going to go to 10.5:1 and have the head flattened (milled) but only flattened. would you need adjustable cam gears or will the stockers suffice? would you need the SAFC for 10.5:1?
another thing that I've been wondering about is how much will it weaken the crankshaft in this kind of situation if the rod bearing journals need to be machined down? or would the crank still be able to support as much HP as it normally can?
#66381, "RE: high comp motors" In response to Reply # 4
If you mill the head you change the timing belt geometry, to bring it back to stock you need adjustable cam gears. A minormill you won't notice the effects. But the more you mill the more noticeable it is.
#66386, "RE: high comp motors" In response to Reply # 5
the crankshaft.... will having it machined at the rod journals affect how much horsepower it will be able to handle? or is that amount not even enough to matter
#66389, "RE: high comp motors" In response to Reply # 6
Originally posted by 95_ESi_Person the crankshaft.... will having it machined at the rod journals affect how much horsepower it will be able to handle? or is that amount not even enough to matter
Nope won't make any difference, it only needs to be machined -IF- it is damaged and needs to be made true, in which case correect size bearings will be needed but since your engine doesn't have problems you don't have to worry about any of that
*Skrilla "Honest officer, I thought you were trying to race me" Talon: 1st 2.4L '97 Prelude '04 350Z
Originally posted by YourInMyMirror95GS dick teaser's should be rounded up and shot in the forehead
Originally posted by etx Good luck man! Project 'STFU Brian your talon is dead meat' should be on it's feet soon!
Originally posted by Dark0ne Thanks. Now excuse me while i fuck your sister.
#66400, "RE: high comp motors" In response to Reply # 8
Originally posted by Skrilla
Originally posted by 95_ESi_Person the crankshaft.... will having it machined at the rod journals affect how much horsepower it will be able to handle? or is that amount not even enough to matter
Nope won't make any difference, it only needs to be machined -IF- it is damaged and needs to be made true, in which case correect size bearings will be needed but since your engine doesn't have problems you don't have to worry about any of that
The amount of material removed in turning a crank or balancing a rotating assembly isn't going to effect the strength of the crank at all.
#66415, "RE: high comp motors" In response to Reply # 10
Originally posted by Michael_97RS
Originally posted by Skrilla
Originally posted by 95_ESi_Person the crankshaft.... will having it machined at the rod journals affect how much horsepower it will be able to handle? or is that amount not even enough to matter
Nope won't make any difference, it only needs to be machined -IF- it is damaged and needs to be made true, in which case correect size bearings will be needed but since your engine doesn't have problems you don't have to worry about any of that
The amount of material removed in turning a crank or balancing a rotating assembly isn't going to effect the strength of the crank at all. Exile Racing Technologies: http://www.exileracing.com una salus victus Mods List: http://highlander.dsmpower.com/sig.htm
I must disagree with you, the amount of material removed will not effect the strength of the shaft unless the machinist removes too much of the radius. Most your strength is in the radius of the crank journals since that is where cracks usually start. Just make sure your machinist has good equipment and does good work and your cool.
#66428, "RE: high comp motors" In response to Reply # 11 Jan-12-04 05:22 PM by DarkOne
This is true, but considering they only sell the bearings in .010, .020, and .030 under, and that we have rather large rod journals, i think you'l be just fine.
If your machinist takes off too much, you either should have just bought a new crank, or your machinist needs replacing.
______________________________ If a sentence found online has 35% misspellings or greater and includes at least two racially charged expletives, chances are it is a YouTube comment.
'95 Eclipse TurboGS (garage deco) '95 TSi AWD (restoring a survivor) '97 Talon ESi-T (poor impulse control) '99 Eclipse RS-T (daily beater) '13 Evo X (mostly stock) '17 Sienna (Middle Aged Dad Mobile)
#66440, "RE: high comp motors" In response to Reply # 11
Originally posted by mrj82 I must disagree with you, the amount of material removed will not effect the strength of the shaft unless the machinist removes too much of the radius. Most your strength is in the radius of the crank journals since that is where cracks usually start. Just make sure your machinist has good equipment and does good work and your cool.
I'll assume your machinist is not in competition with a garden slug for brain cells and I'll stand by my statement. Of course an untrained monkey could turn your crank and balance your rotation assembly... but I wouldn't take my parts there.
#66444, "RE: high comp motors" In response to Reply # 13 Jan-13-04 04:21 AM by mrj82
Personally I've done my machine work myself. Its pretty easy to mess up a crank if your in a hurry and try to halfass it as I've seen done before. If you don't dress your stone and put a new radius on there for each different crank yeah you might have problems in a high horsepower applications. Althought it wouldn't matter for a stock engine. Point is the strength is in the radius. Turning the crank .050" under wouldn't take any strength away, it would be just fine as long as you can get bearings that size. I've ground at least 50 cranks when I went to college to learn this stuff and never fucked one up. Too bad I choose not to do it for a living considering pay around here is pretty low for that sort of thing. I make more money at the car audio shop I work for then I would at a local machine shop. One of them was only offering to pay $6.00 an hour. Think about that one, your getting a $6.00 an hour job on your machine work.
Edit: One more thing, our college has better equipment then any performance shop in the state. Except for one place that has a flow bench we didn't have.
#66445, "RE: high comp motors" In response to Reply # 14
Granted.
______________________________ If a sentence found online has 35% misspellings or greater and includes at least two racially charged expletives, chances are it is a YouTube comment.
'95 Eclipse TurboGS (garage deco) '95 TSi AWD (restoring a survivor) '97 Talon ESi-T (poor impulse control) '99 Eclipse RS-T (daily beater) '13 Evo X (mostly stock) '17 Sienna (Middle Aged Dad Mobile)
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