.020 overbore : Approx hp/tq gains on 4.6
11-04-2006, 01:17 AM
#11
3rd Gear Member
Thread Starter
Join Date: Aug 2006
Location: Upstate NY
Posts: 621
RE: .020 overbore : Approx hp/tq gains on 4.6
ORIGINAL: droptoppony
some will do a .020 over on an engine rebuild then if they make a change take it out to .030 over...modular blocks shouldn't be taken out much more then that thus the reason for resleeving them when going with a big bore. Now a big bore will add some power.
ORIGINAL: Armydad
thanks for the response, I agree that perhaps.020 is more of a trueing of the cylider walls, but why then would someone need to go bigger? To increase displacement and make more power. if you need to overbore .040-.060 just to true the walls, you should look for a new block.
ORIGINAL: JD1969
You don't bore an engine for added HP. Boring is done to true the cylinder walls and provide a good seal for the rings.
You don't bore an engine for added HP. Boring is done to true the cylinder walls and provide a good seal for the rings.
yeah, Ive been reading up on those big bores, they seem to be more race oriented than daily driver. I don't think busting out the walls will buy me anything, so i'll prolly do staight rebuild.
11-04-2006, 05:04 AM
#12
2nd Gear Member
Join Date: Apr 2006
Location:
Posts: 417
RE: .020 overbore : Approx hp/tq gains on 4.6
It all depends on how worn the cylinders are. If there only .001-.002 over stock you can just flash hone it and re-ring it. If its any more then that then you'll have to bore it .010 or .020, depending on what pistons are available. Boring it .020 would give you about 1-2 HP as stated before, good luck.
11-04-2006, 08:23 AM
#14
6th Gear Member
Join Date: Jan 2004
Location: United States
Posts: 12,575
RE: .020 overbore : Approx hp/tq gains on 4.6
ORIGINAL: Stang9946
Why do you think guys take 350s and stroke them to 383s? More power! More potential! You don't bore out a 350 30 over and put a 400 block crank and pistons in it to seal rings. Don't know where you got your information from.
ORIGINAL: JD1969
You don't bore an engine for added HP. Boring is done to true the cylinder walls and provide a good seal for the rings.
You don't bore an engine for added HP. Boring is done to true the cylinder walls and provide a good seal for the rings.
No way no how, on any engine, that you are seeing any significant power increases with a .20 overbore, modular OR 350 chevy. The only way you could/would see a power increase is if the original engine is running so badly that you repair compression loss etc.
People overbore to a .40+ because the cyl ARE that damaged, or because they have already done so once to .20 and need more. A modular block without sleeving will not do this anyway.
In a single sentance: Completely worthless as a power mod.
11-04-2006, 08:44 AM
#15
6th Gear Member
Join Date: Jan 2004
Location: United States
Posts: 12,575
RE: .020 overbore : Approx hp/tq gains on 4.6
ORIGINAL: Armydad
Well actually I will be having ported SVO heads a Crower blower cam and probably the FRPP s/c. Also headers full exhaust, CAI, TB, I probably should have mentioned all that, sorry.
Well actually I will be having ported SVO heads a Crower blower cam and probably the FRPP s/c. Also headers full exhaust, CAI, TB, I probably should have mentioned all that, sorry.
ORIGINAL: 2000GT4.6
A .20 will add virtually nothing to your 2v car, espcially with stock heads/cams/intake. Even most of the stroker kits do not add alot of power on built cars.
A .20 will add virtually nothing to your 2v car, espcially with stock heads/cams/intake. Even most of the stroker kits do not add alot of power on built cars.
Also, unless you plan on running an aftermarket shortblock the heads are a waste of time and energy. The proper supercharger setup along with a set of blower cams will have the factory shortblock on the limit without spending 1500 bucks on heads.
11-04-2006, 11:56 AM
#16
3rd Gear Member
Thread Starter
Join Date: Aug 2006
Location: Upstate NY
Posts: 621
RE: .020 overbore : Approx hp/tq gains on 4.6
ORIGINAL: 2000GT4.6
BTW, in case nobody told ya yet, the FRPP blower sucks. Putting a FRPP blower on a car with ported heads and blower cams is like putting slicks on my old stock 88 bird. I am sure it would be faster than without the slicks, but its still silly.
Also, unless you plan on running an aftermarket shortblock the heads are a waste of time and energy. The proper supercharger setup along with a set of blower cams will have the factory shortblock on the limit without spending 1500 bucks on heads.
ORIGINAL: Armydad
Well actually I will be having ported SVO heads a Crower blower cam and probably the FRPP s/c. Also headers full exhaust, CAI, TB, I probably should have mentioned all that, sorry.
Well actually I will be having ported SVO heads a Crower blower cam and probably the FRPP s/c. Also headers full exhaust, CAI, TB, I probably should have mentioned all that, sorry.
ORIGINAL: 2000GT4.6
A .20 will add virtually nothing to your 2v car, espcially with stock heads/cams/intake. Even most of the stroker kits do not add alot of power on built cars.
A .20 will add virtually nothing to your 2v car, espcially with stock heads/cams/intake. Even most of the stroker kits do not add alot of power on built cars.
Also, unless you plan on running an aftermarket shortblock the heads are a waste of time and energy. The proper supercharger setup along with a set of blower cams will have the factory shortblock on the limit without spending 1500 bucks on heads.
I am sorry I thought I had mentioned earlier that, Yes I am going to forge the bottom end (SHM has a nice kit for $1500). You are absolutely correct, putting those heads on a stock bottom end would not be optimal, but it can be done along with some other mods and should get you around 320-340 hp. Adding a blower to this combo (stock bottom) would eventually grenade the motor .
As far as the blower, what makes it silly if I get 100hp out of it and I am happy with that hp level? 400 ponies is nothing to sneeze at.
I am not glued to any of my plans, things change, oportunities present themselves, i will stay flexible. I might have a good deal on a Vortech that I am negotiating, for the right price I will scap it up and replan the rest of the build.
Again thanks for all the good responses/info
11-04-2006, 12:14 PM
#17
Pro. B.S. caller outer
Join Date: May 2004
Location: IL
Posts: 9,644
RE: .020 overbore : Approx hp/tq gains on 4.6
ORIGINAL: Stang9946
Why do you think guys take 350s and stroke them to 383s? More power! More potential! You don't bore out a 350 30 over and put a 400 block crank and pistons in it to seal rings. Don't know where you got your information from.
ORIGINAL: JD1969
You don't bore an engine for added HP. Boring is done to true the cylinder walls and provide a good seal for the rings.
You don't bore an engine for added HP. Boring is done to true the cylinder walls and provide a good seal for the rings.
ORIGINAL: 2000GT4.6
A stroker kit is adding much more CI than a simple bore job
No way no how, on any engine, that you are seeing any significant power increases with a .20 overbore, modular OR 350 chevy. The only way you could/would see a power increase is if the original engine is running so badly that you repair compression loss etc.
People overbore to a .40+ because the cyl ARE that damaged, or because they have already done so once to .20 and need more. A modular block without sleeving will not do this anyway.
In a single sentance: Completely worthless as a power mod.
ORIGINAL: Stang9946
Why do you think guys take 350s and stroke them to 383s? More power! More potential! You don't bore out a 350 30 over and put a 400 block crank and pistons in it to seal rings. Don't know where you got your information from.
ORIGINAL: JD1969
You don't bore an engine for added HP. Boring is done to true the cylinder walls and provide a good seal for the rings.
You don't bore an engine for added HP. Boring is done to true the cylinder walls and provide a good seal for the rings.
No way no how, on any engine, that you are seeing any significant power increases with a .20 overbore, modular OR 350 chevy. The only way you could/would see a power increase is if the original engine is running so badly that you repair compression loss etc.
People overbore to a .40+ because the cyl ARE that damaged, or because they have already done so once to .20 and need more. A modular block without sleeving will not do this anyway.
In a single sentance: Completely worthless as a power mod.
11-04-2006, 12:39 PM
#18
5th Gear Member
Join Date: Dec 2004
Location: In between Your Mom's Titties, skeet skeet..
Posts: 2,045
RE: .020 overbore : Approx hp/tq gains on 4.6
Maybe people don't know math, or measurements very well, since .020" is 2 HUNDRETHS of an inch, or roughly .51mm..
Although compounded over all 8 cylinders, it won't make a difference, especially when there are 25.4mm per 1 (length/width not volume/displacement.)
JT
Although compounded over all 8 cylinders, it won't make a difference, especially when there are 25.4mm per 1 (length/width not volume/displacement.)
JT
11-04-2006, 12:41 PM
#19
3rd Gear Member
Thread Starter
Join Date: Aug 2006
Location: Upstate NY
Posts: 621
RE: .020 overbore : Approx hp/tq gains on 4.6
Thanks,
Being as how I'm doing the bottom end either way, would it be worth a little extra to stroke it? I have no experience as far as a stroked 4.6, some people say good some say worthless, are there any gains?
Being as how I'm doing the bottom end either way, would it be worth a little extra to stroke it? I have no experience as far as a stroked 4.6, some people say good some say worthless, are there any gains?
11-04-2006, 01:40 PM
#20
Pro. B.S. caller outer
Join Date: May 2004
Location: IL
Posts: 9,644
RE: .020 overbore : Approx hp/tq gains on 4.6
ORIGINAL: Armydad
Thanks,
Being as how I'm doing the bottom end either way, would it be worth a little extra to stroke it? I have no experience as far as a stroked 4.6, some people say good some say worthless, are there any gains?
Thanks,
Being as how I'm doing the bottom end either way, would it be worth a little extra to stroke it? I have no experience as far as a stroked 4.6, some people say good some say worthless, are there any gains?