compression?
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Zombie Survivalist
Joined: Feb 2009
Posts: 14,809
Likes: 3
From: Rock Springs, WY, USA
compression?
ok, this is more of a question for the engine buildin gurus.
if im not mistaken, the EFI 460s have 95cc combustion chambers. what compression ratio does this give them? 8/8.5:1? if i had .005" milled off the heads, with some single-layer copper gaskets, what may i see for an increase? with a stout torque cam and strait-up timin, would this create any risk of a valve-piston collision?
just curiosities for buildin a stout, reliable pullin motor without pullin it outta the truck. my brainstorm says poppin the heads, gasket matched p&p, millin the heads to bump up the CR, a stout hydro-roller torque cam that will build from 1200 to 3400, strait-up timin, stiffer push-rods and valve springs, and a set of long tube headers. only goal: to build a 1:1 CI/TQ ratio, and put peak torque between 2200 and 2800 rpms. this would be ideal for highway cruisin with a ZF/4:10 gear ratio combo.
after thought: the above build with an eaton intercooled supercharger pushin 6-8 psi. thoughts?
if im not mistaken, the EFI 460s have 95cc combustion chambers. what compression ratio does this give them? 8/8.5:1? if i had .005" milled off the heads, with some single-layer copper gaskets, what may i see for an increase? with a stout torque cam and strait-up timin, would this create any risk of a valve-piston collision?
just curiosities for buildin a stout, reliable pullin motor without pullin it outta the truck. my brainstorm says poppin the heads, gasket matched p&p, millin the heads to bump up the CR, a stout hydro-roller torque cam that will build from 1200 to 3400, strait-up timin, stiffer push-rods and valve springs, and a set of long tube headers. only goal: to build a 1:1 CI/TQ ratio, and put peak torque between 2200 and 2800 rpms. this would be ideal for highway cruisin with a ZF/4:10 gear ratio combo.
after thought: the above build with an eaton intercooled supercharger pushin 6-8 psi. thoughts?
Posting Guru
Joined: Jan 2006
Posts: 1,101
Likes: 2
From: Malvern, Ohio
You will be needing to buy or borrow some tools here if you are serious. If you want to mill the heads etc. Start at square one. Remove yourheads, check your deck height, CC your chambers find a reliable porter or just contact the Mad Porter Scotty to save time.
Milling your heads and switch to a thinner HG, your pushrod length will be effected. Also you are closer to the pistons especially with a different cam with more radical attributes.
Get the information on your base measurements which are needed first especially if you plan on reworking both the combustion chamber and piston crown (Deck height, chamber CCs(before and after work if done), piston dish etc)
Milling your heads and switch to a thinner HG, your pushrod length will be effected. Also you are closer to the pistons especially with a different cam with more radical attributes.
Get the information on your base measurements which are needed first especially if you plan on reworking both the combustion chamber and piston crown (Deck height, chamber CCs(before and after work if done), piston dish etc)
Thread Starter
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Zombie Survivalist
Joined: Feb 2009
Posts: 14,809
Likes: 3
From: Rock Springs, WY, USA
thanks jim. i know the push rods are gonna need to be bit shorter, but in doin this sort of work, is it gonna throw a rod down onto a piston, or the piston into the head. my main points of concern are A: collisions, and B: too much compression. i know its a lot to ask, but im wantin to still be able to run 87. or is that gonna be too much to ask?
the ZF wont handle it? you said the 42. what other variations are there?
the ZF wont handle it? you said the 42. what other variations are there?
Lead Driver
Joined: Mar 2004
Posts: 8,922
Likes: 153
You will never notice cutting .005 off a head. Not sure on the stock cc but D3's are close to 95cc & I doubt FI chambers are the same. You need to zero deck the block. The pistons are way too far in the hole from the factory causing low compression and detonation.
Valve to piston clearance should always be checked. FI pistons don't have much of a valve relief in them. If you zero deck it and put a big cam in, it probably won't have enough clearance. Hydro rollers aren't a good choice for a big block. You probably will have to cut the valve guides down some if you put a big cam in. There usually isn't enough clearance in there for the stem seals with a big cam.
Valve to piston clearance should always be checked. FI pistons don't have much of a valve relief in them. If you zero deck it and put a big cam in, it probably won't have enough clearance. Hydro rollers aren't a good choice for a big block. You probably will have to cut the valve guides down some if you put a big cam in. There usually isn't enough clearance in there for the stem seals with a big cam.
Thread Starter
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Zombie Survivalist
Joined: Feb 2009
Posts: 14,809
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From: Rock Springs, WY, USA
ok. gettin more in depth now... not deckin the block, upgradin to a 4 inch stroke crank, with rods and pistons to match, again, a good low/mid-range torque hydro (maybe a flat-tappet instead of a roller?) cam, and the before mentioned head work?
Posting Guru
Joined: Jan 2006
Posts: 1,101
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From: Malvern, Ohio
If you want to run 87, you are definitely going to have to get your cylinder pressure as equal as possible (adequate swirl) throughout the chamber and get your heads flowing well.
If you want a supercharger, you won't be running 87 octane period.
If you want a supercharger, you won't be running 87 octane period.
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Zombie Survivalist
Joined: Feb 2009
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From: Rock Springs, WY, USA
i kinda figured 87 would be stretch. im ok with payin the extra buck for 93, considerin the power level.
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Dont forget that dependent upon the application, more expensive higher octane fuel can actually save you $$ over the cheaper lower octane. Its a simple process with a ECU and a knock sensor, but the same principal without. More timing more power, less timing less power. If you (or the computer) pull timing to control detonation, MPG will suffer. With the difference in CPG so close, upping a grade to advace timing can actually save you $$ both in MPG and longevity. Of course if your not at a performace level that can use the bump in timing, then you are just wasting $$.
Posting Guru
Joined: Jan 2006
Posts: 1,101
Likes: 2
From: Malvern, Ohio
Dont forget that dependent upon the application, more expensive higher octane fuel can actually save you $$ over the cheaper lower octane. Its a simple process with a ECU and a knock sensor, but the same principal without. More timing more power, less timing less power. If you (or the computer) pull timing to control detonation, MPG will suffer. With the difference in CPG so close, upping a grade to advace timing can actually save you $$ both in MPG and longevity. Of course if your not at a performace level that can use the bump in timing, then you are just wasting $$.
I do agree on the fuel comment fully Bobby. A lot of people just dump 87 in just because its the cheapest. Depending on the persons vehicle, mid-grade for example, could produce better mileage and better combustion simply because the engine might have been designed to run on an octane higher than 87. Same could be for other situations.
460/5 has alot to look at, lots of good help on the board. A couple of them replied in this thread that I have had followed some advice in the past.
Senior User
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I wouldn't say more timing = more power all the time or less = less. One thing you create with too much advancement is either detonation, preignition or if those aren't occurring, pumping loss. Timing that is retarded too much will raise your exhaust temperature and you will miss peak pressure point just after TDC. But it comes down to what you mentioned at the start of your post, dependant on the application, dictates the setting that best suits it.
I do agree on the fuel comment fully Bobby. A lot of people just dump 87 in just because its the cheapest. Depending on the persons vehicle, mid-grade for example, could produce better mileage and better combustion simply because the engine might have been designed to run on an octane higher than 87. Same could be for other situations.
460/5 has alot to look at, lots of good help on the board. A couple of them replied in this thread that I have had followed some advice in the past.
I do agree on the fuel comment fully Bobby. A lot of people just dump 87 in just because its the cheapest. Depending on the persons vehicle, mid-grade for example, could produce better mileage and better combustion simply because the engine might have been designed to run on an octane higher than 87. Same could be for other situations.
460/5 has alot to look at, lots of good help on the board. A couple of them replied in this thread that I have had followed some advice in the past.
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