Cam for Big Cubes. How do I scale up from a 346?
08-07-2004, 04:30 PM
#1
Cam for Big Cubes. How do I scale up from a 346? I've had a number of cams in my 346 and know how they feel and what their drivibality is. As I look to bigger cubes, how do I scale up to acheive the same relative drivability / performance trade off?
For example, in a 346, the 224/224 has become a benchmark cam. Decent power and near stock manners with simple tuning. what would be the equivalent cam for a 383 stroker, Iron 408, or 422?
For example, in a 346, the 224/224 has become a benchmark cam. Decent power and near stock manners with simple tuning. what would be the equivalent cam for a 383 stroker, Iron 408, or 422?
08-07-2004, 04:34 PM
#2
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depends on the lobe type and exactly what you are looking for.
A 232/232 on 114 in a 385 will behave similar to a 224/224 112 in stock cubes.
My 236/240 110LSA cam is surprisingly mild
A 232/232 on 114 in a 385 will behave similar to a 224/224 112 in stock cubes.
My 236/240 110LSA cam is surprisingly mild
08-07-2004, 06:45 PM
#3
You would want to take your combo as a whole then decide what camshaft. I'd factor in Intake, Heads, CID, the Bore and Stroker (which one is larger or is it square), the compression, the quench height, all that.
If you have 2 motors the same CID but one has a higher compression ratio. The one with the higher compression ratio would be able to tolerate a larger camshaft and still remain streetable.
If you have 2 motors the same CID but one has a higher compression ratio. The one with the higher compression ratio would be able to tolerate a larger camshaft and still remain streetable.
08-07-2004, 08:48 PM
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Cam size and Engine size do not grow linearly (Is that a word?).
There are way too many variables that lead to camshaft choice for that to be possible. If you're looking for a cam matched for your application, you need to hire th expertise of a well-known camshaft grinder (I.E. Ed Curtis/Erik Koenig, not Comp/Lunati).
There are way too many variables that lead to camshaft choice for that to be possible. If you're looking for a cam matched for your application, you need to hire th expertise of a well-known camshaft grinder (I.E. Ed Curtis/Erik Koenig, not Comp/Lunati).
08-07-2004, 08:49 PM
#6
Why such of a low compression ratio??? You'd be looking at something w/ mid to upper 230's on the duration on the exhaust side and upper 230's to lower 240's on the duration. This is just a guess, w/o knowing all the info. Personally I'd aim for more compression than 10.8-11.2 even if you're on 93 octane.
08-07-2004, 08:51 PM
#7
Originally Posted by KingCrapBox
Cam size and Engine size do not grow linearly (Is that a word?).
There are way too many variables that lead to camshaft choice for that to be possible. If you're looking for a cam matched for your application, you need to hire th expertise of a well-known camshaft grinder (I.E. Ed Curtis/Erik Koenig, not Comp/Lunati).
There are way too many variables that lead to camshaft choice for that to be possible. If you're looking for a cam matched for your application, you need to hire th expertise of a well-known camshaft grinder (I.E. Ed Curtis/Erik Koenig, not Comp/Lunati).
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08-08-2004, 08:36 AM
#8
Originally Posted by MUSTANGEATER
Why such of a low compression ratio??? You'd be looking at something w/ mid to upper 230's on the duration on the exhaust side and upper 230's to lower 240's on the duration. This is just a guess, w/o knowing all the info. Personally I'd aim for more compression than 10.8-11.2 even if you're on 93 octane.
I was thinking along the lines you appear to be suggesting; maybe a 236/232 for a 383 or 240/236 for a 408.
08-08-2004, 08:45 AM
#9
Originally Posted by KingCrapBox
Cam size and Engine size do not grow linearly (Is that a word?).
08-08-2004, 10:17 AM
#10
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I believe a good rule of thumb is 6 to 8 degrees for every 50 ci.So if you go to a 408 you could use a 230 or 232 cam and be close to the 224 in a 346.You may go 236 and be OK,remember that a longer stroke say 4" changes your rod to stroke ratio and increases piston acceleration so a tighter lobe separation should work better.Go with as much lift as you can. 
08-08-2004, 03:20 PM
#11
My 230/228 114 in a 387 felt exactly to me like the 221/221 114 that i hade in it before with the 346. Im moving to a 236-236 114 (mti Z1) assuming that the idle will roughly resemble my 224/224 112 in the 346.
The 230/228 114 peaked at a low 5800 rpm in the 387 all bore. These larger CI engines take alot more cam than I expected. If I was going to 427, (which I still plan on someday when Im comfortable with my resleeve) I would think a 242/242 114 would be surprisingly mild. Thats 20 degrees more than the original 221 or 222 that my MTI C1 was and should idle/peak somewhere similarly..
The 230/228 114 peaked at a low 5800 rpm in the 387 all bore. These larger CI engines take alot more cam than I expected. If I was going to 427, (which I still plan on someday when Im comfortable with my resleeve) I would think a 242/242 114 would be surprisingly mild. Thats 20 degrees more than the original 221 or 222 that my MTI C1 was and should idle/peak somewhere similarly..
08-08-2004, 06:53 PM
#12
Originally Posted by Ragtop 99
I hadn't thought about going over 11.5:1. Does the fact that its 408 make it easier to run more compression than a 346?
I was thinking along the lines you appear to be suggesting; maybe a 236/232 for a 383 or 240/236 for a 408.
I was thinking along the lines you appear to be suggesting; maybe a 236/232 for a 383 or 240/236 for a 408.
Well the larger bore 4.030 vs 3.90X does help, but you can get away w/ more than 11.5:1 on a 3.90X w/o a problem. I wouldn't be surprised if someone could get away w/ 13.0:1 compression on a 4.125 + bore on 93 octane.
You can't just hodge podge it together. So make sure all your parts are matched together correctly and the camshaft is selected by someone who knows wtf he's doing and not the average internet guru.
I think in a higer compression motor you'll find a 240/236 will be a lil bit smaller than you would want to go towards.
08-09-2004, 01:00 PM
#13
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Originally Posted by MUSTANGEATER
Well the larger bore 4.030 vs 3.90X does help, but you can get away w/ more than 11.5:1 on a 3.90X w/o a problem. I wouldn't be surprised if someone could get away w/ 13.0:1 compression on a 4.125 + bore on 93 octane.
Part of what you said is true though. You can run a static compression ratio of 13:1 and still have a 93 Octane motor. You'll just need to pick a camshaft that will lower the dynamic compression ratio.
If you're looking for a good, reliable stroker motor that isn't 'max-effort' but does hold it's own, a static compression ratio of about 11.5:1 is typically a good ballpark figure.
As you're probably beginning to see, all of this can get pretty complicated. That's why it's sometimes best to pay true professionals to put together a motor for you based on your goals and budget.
08-09-2004, 02:48 PM
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This is my head
This is my head after reading and trying to understand all of these posts
As you're probably beginning to see, all of this can get pretty complicated. That's why it's sometimes best to pay true professionals to put together a motor for you based on your goals and budget.
This is my head after reading and trying to understand all of these posts
Originally Posted by KingCrapBox
As you're probably beginning to see, all of this can get pretty complicated. That's why it's sometimes best to pay true professionals to put together a motor for you based on your goals and budget.
08-09-2004, 03:03 PM
#15
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I was wondering about this myself, but I never got any hard answers.
If it helps, my TR220 on a 112 runs pretty good on a stock tune in a A4 6.0. I kind of wish I went bigger.
If it helps, my TR220 on a 112 runs pretty good on a stock tune in a A4 6.0. I kind of wish I went bigger.
08-09-2004, 11:41 PM
#16
Bore size and static compression ratio don't increase linearly either. Just because you magically get a bigger bore doesn't mean you can throw more compression at the motor and expect to get away with it.
Well yea I wasn't saying all that, prolly came across that way there's a lot more to it.
As you're probably beginning to see, all of this can get pretty complicated. That's why it's sometimes best to pay true professionals to put together a motor for you based on your goals and budget.
Ding Ding Ding we have a winner.
