Ok, new thread to get back on track....
Rich has done some research and told me about the C6 'box, after a very quick search on US ebay I see they are direct BBF fitment which would make things easier, and can handle 550-600bhp in standard form.
So with the TH400 being so cheap and easy to get hold of I'm trying to compare the 2, and throwing the C4 in there too as I know people like it. What are the pro's and con's of each box?
TH400 - C4 - C6
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topcatcustom
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hi Tom
have you a basic spec for your engine yet so as you have a rough idea of the power you are after? even a basic displacment would be a start. without it I don't see how you are going to work out a spec for the box. what use is it going to be used for, street crusing? slingshot dragster? bracket race car? rock crawler?
sorry to be dull but If you can give us some idea, or have you and I've missed it.
Say you are building 460 ford pretty basic spec of 30 over bore, pocket ported factory heads, 9.75 to one compression, single 4 barrel on a duel plane manifold (850 double pumper carb?) and about 230 deg of lift at .05", no nitrous nothing fancy, put together right should see 500 to 550 bhp, and 550 to 600 ft lb of torque maybe a little more. Then stick it in a tone and a half of car and either box will be fine for road use and weekend drag runs.
stick it in a drag chassis all up less than a ton with a set of big fat slicks then I would go for a 2 speed and a loose ish torque converter.
Spend a little money on decent ally heads (or fing someone who knows how to port the existing ones) some off the shelf forged pistons, say 4.45" bore and a common long throw crank, say a 4.25" then you are looking at 530 ci still not large, but it will let the heads breathe, add to tat a decent amount of cam (still be able to drive it to the shops) say 255 deg inlet and 262 exhaust at .05 on a mechanical roller pattern on a pair of 750s on a tunnel ram and you are in the region of 780 to 850bhp easy. and well over 750 flbs, now your box will be working for it's keep.
we arnt even talking addin NOs yet, but a 2 stage 350 shot would easily go into the firstengine spec and 450 in the second with the ported heads and 500-550 with the ally ones.
As I said in your first post on this subject big block tuning isn't the same as small blocks and rovers, they arn't head limited the same way, also they can tame cams that would give a 383 stroker SBC an idle as rough as a badgers butt.
260 degrees of timing at .05 on a roller cam is street drivable on an LSA of 110 degrees on a 500ci engine, with 12.5 to 1 compression of supermarket unleaded with square port factory heads that is easily 700 bhp on that size engine without reving it.
Based on this principle big block tuning is about the building the right bottom end and chosing the right displacment, take a 500ci example in the paragraph above that I used to illustrate the cam timing add 50ci with a 4.5 inch crank and you will add 50 to 60bhp and the same in torque.
I am really trying my best to help here, I don't want to put you off in any way, I am envious you can look at building a big block. I've been reading up on building them for at least 20 years probably 25 (I would love to be able to consider doing it myself). But to succeed without throwing 10s of thousands of pounds in broaken gearboxes and wrong engine components you have to have a plan for the engine and drive train that works together and matches the use of the car, this means being clear on where you are going with this. When everyone was going 5 and 6 speed gearboxes in race cars in the early '70s the mclaren M8f went from a 5 speed to a 4 and went faster because they had a big block in the back.
Best regards
Mike
have you a basic spec for your engine yet so as you have a rough idea of the power you are after? even a basic displacment would be a start. without it I don't see how you are going to work out a spec for the box. what use is it going to be used for, street crusing? slingshot dragster? bracket race car? rock crawler?
sorry to be dull but If you can give us some idea, or have you and I've missed it.
Say you are building 460 ford pretty basic spec of 30 over bore, pocket ported factory heads, 9.75 to one compression, single 4 barrel on a duel plane manifold (850 double pumper carb?) and about 230 deg of lift at .05", no nitrous nothing fancy, put together right should see 500 to 550 bhp, and 550 to 600 ft lb of torque maybe a little more. Then stick it in a tone and a half of car and either box will be fine for road use and weekend drag runs.
stick it in a drag chassis all up less than a ton with a set of big fat slicks then I would go for a 2 speed and a loose ish torque converter.
Spend a little money on decent ally heads (or fing someone who knows how to port the existing ones) some off the shelf forged pistons, say 4.45" bore and a common long throw crank, say a 4.25" then you are looking at 530 ci still not large, but it will let the heads breathe, add to tat a decent amount of cam (still be able to drive it to the shops) say 255 deg inlet and 262 exhaust at .05 on a mechanical roller pattern on a pair of 750s on a tunnel ram and you are in the region of 780 to 850bhp easy. and well over 750 flbs, now your box will be working for it's keep.
we arnt even talking addin NOs yet, but a 2 stage 350 shot would easily go into the firstengine spec and 450 in the second with the ported heads and 500-550 with the ally ones.
As I said in your first post on this subject big block tuning isn't the same as small blocks and rovers, they arn't head limited the same way, also they can tame cams that would give a 383 stroker SBC an idle as rough as a badgers butt.
260 degrees of timing at .05 on a roller cam is street drivable on an LSA of 110 degrees on a 500ci engine, with 12.5 to 1 compression of supermarket unleaded with square port factory heads that is easily 700 bhp on that size engine without reving it.
Based on this principle big block tuning is about the building the right bottom end and chosing the right displacment, take a 500ci example in the paragraph above that I used to illustrate the cam timing add 50ci with a 4.5 inch crank and you will add 50 to 60bhp and the same in torque.
I am really trying my best to help here, I don't want to put you off in any way, I am envious you can look at building a big block. I've been reading up on building them for at least 20 years probably 25 (I would love to be able to consider doing it myself). But to succeed without throwing 10s of thousands of pounds in broaken gearboxes and wrong engine components you have to have a plan for the engine and drive train that works together and matches the use of the car, this means being clear on where you are going with this. When everyone was going 5 and 6 speed gearboxes in race cars in the early '70s the mclaren M8f went from a 5 speed to a 4 and went faster because they had a big block in the back.
Best regards
Mike
poppet valves rule!
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topcatcustom
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Mike, I had mentioned in the other thread that the plan is for it to go into a Jag XJS, so a fairly heavy car, but designed for a heavy engine too.
I like the idea of increasing capacity on a bbf 460, but it may be a bit out of my price range and it may be cheaper to use nitrous to get another couple of hundred bhp. I'd really like to see around 600bhp, dont care about torque as I know it will be about a thousand time more than I need anyway!!!
How much will a +30 bore increase capacity on a 460, and do you have any idea what price a longer throw crank would cost? I assume for that sort of power I would need forged pistons, and to rev and perhaps use nos I would probably pop a set of H beam rods in there too, so putting a longer throw crank in may as well be done at the same time, as I would already be replacing the stock pistons and rods. So perhaps looking at 510-530ci?
Ally heads would go on for a massive weight saving and better flow, I'm not 100% sure about injection or carbs, but I cant escape the fact that I love the old skool twin AFB look on a big V8, and MSD red HT stuff!!
Would be looking to use it on the roads and on the drag strip, but want it completely reliable so I can give it hell up the strip without worrying if I can drive it home again after! The crate engines I have seen in the states say about 575bhp out of a 515ci ford which seems low, but am I right in thinking their pump gas is basically crap? We can easily get 98-100 octane juice, which means we can crank up the compression ratio maybe more than they can over the water...
So basically, circa 600bhp (probably wouldn't feel the need for nos (at least for a while)), and a mountain of torque. The car weighs 1.7 tonnes, bbf is the same weight as the V12, and I'm sure I could strip at least 100kgs out of it.
I like the idea of increasing capacity on a bbf 460, but it may be a bit out of my price range and it may be cheaper to use nitrous to get another couple of hundred bhp. I'd really like to see around 600bhp, dont care about torque as I know it will be about a thousand time more than I need anyway!!!
How much will a +30 bore increase capacity on a 460, and do you have any idea what price a longer throw crank would cost? I assume for that sort of power I would need forged pistons, and to rev and perhaps use nos I would probably pop a set of H beam rods in there too, so putting a longer throw crank in may as well be done at the same time, as I would already be replacing the stock pistons and rods. So perhaps looking at 510-530ci?
Ally heads would go on for a massive weight saving and better flow, I'm not 100% sure about injection or carbs, but I cant escape the fact that I love the old skool twin AFB look on a big V8, and MSD red HT stuff!!
Would be looking to use it on the roads and on the drag strip, but want it completely reliable so I can give it hell up the strip without worrying if I can drive it home again after! The crate engines I have seen in the states say about 575bhp out of a 515ci ford which seems low, but am I right in thinking their pump gas is basically crap? We can easily get 98-100 octane juice, which means we can crank up the compression ratio maybe more than they can over the water...
So basically, circa 600bhp (probably wouldn't feel the need for nos (at least for a while)), and a mountain of torque. The car weighs 1.7 tonnes, bbf is the same weight as the V12, and I'm sure I could strip at least 100kgs out of it.
TC
with to much power you will have trouble getting the power down, as if i remember right you want a sleeper look??. To re-stroke upto a 521 its about £1300 to £1500 for the kit FORGED PISTONS AND RINGS ,H-BEAM RODS AND CAST STEEL CRANK and bearings, In my own opinion the C6 box would be better as no need for plates to be made , with a 300 shot of gas and a normalish build 900 hp is easy, axle will be the problem 
rich www.carcraft.com/.../ccrp...big_block_f ... index.html , have a read of this
rich www.carcraft.com/.../ccrp...big_block_f ... index.html , have a read of thisNightbreed racing, http://www.youtube.com/watch?v=NJoUTZ8UUps
Sorry I forgot you were going for an xjs
From Bone's research it looks like prices are down allot, my SBC all forged 383 bottom end kit was 1440 pounds plus shipping, that spec bottom end would see you to 850+ without gas and take another 250 at least. 600 bhp can be done with cast pistons and crank but rules out more than another 150 of gas.
If you are going ally heads then I would do a bit of research as it is easy to buy heads that will overwhelm a cam that does not have enough timing.
most of my research is on the BBC, mopar wedge and ford FE series, the 460 series are a better design than all three. If you went for a bottom end kit as above, a set of ally oval port heads , single 850 on a single plane manifold (high riser so it sticks out the bonnet nicely) and about 245 degrees at .05 you should see 750 bhp and 700 ft lb of torque without gas. in this spec it would be far from stressed, make peak power at about 5.8 to 6K revs you wouldn't rev it beyond about 6.3K
Bones is also right about overwhelming the tires, in a car the weight of the jag you will have allot of trouble with traction because you won't be able to get big enough tires under the arches. I would recommend you convert to a ford 9" and use either a 3 speed auto and a high rear end gear or a powerglide (2 speed) and slightly lower gearing. (you could either look for a manual lock up converter or an overdrive unit for the power glide, I think GKN make one. The Powerglide I think is the way to go, the design will inherently take more torque as everything still spins in the same direction after a shift, in the torqueflight design he change from 1st to 2nd has a third of the box spin in the reverse direction after selection, in a hard full power shift there are some serious acceleration forces involved, this tends to be where the box fails.
From Bone's research it looks like prices are down allot, my SBC all forged 383 bottom end kit was 1440 pounds plus shipping, that spec bottom end would see you to 850+ without gas and take another 250 at least. 600 bhp can be done with cast pistons and crank but rules out more than another 150 of gas.
If you are going ally heads then I would do a bit of research as it is easy to buy heads that will overwhelm a cam that does not have enough timing.
most of my research is on the BBC, mopar wedge and ford FE series, the 460 series are a better design than all three. If you went for a bottom end kit as above, a set of ally oval port heads , single 850 on a single plane manifold (high riser so it sticks out the bonnet nicely) and about 245 degrees at .05 you should see 750 bhp and 700 ft lb of torque without gas. in this spec it would be far from stressed, make peak power at about 5.8 to 6K revs you wouldn't rev it beyond about 6.3K
Bones is also right about overwhelming the tires, in a car the weight of the jag you will have allot of trouble with traction because you won't be able to get big enough tires under the arches. I would recommend you convert to a ford 9" and use either a 3 speed auto and a high rear end gear or a powerglide (2 speed) and slightly lower gearing. (you could either look for a manual lock up converter or an overdrive unit for the power glide, I think GKN make one. The Powerglide I think is the way to go, the design will inherently take more torque as everything still spins in the same direction after a shift, in the torqueflight design he change from 1st to 2nd has a third of the box spin in the reverse direction after selection, in a hard full power shift there are some serious acceleration forces involved, this tends to be where the box fails.
poppet valves rule!
