lots of C4 performance questions
04-24-2004, 03:49 PM
#1
Melting Slicks
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lots of C4 performance questions
Yes, I know I have yet to buy my vette, but that is coming soon, and its never too early to start planning right? So without further ado:
1) Is there any HP/TQ gain with shorty headers?
2) Long tube headers - will they work with cats and a B&B cat-back system? What sort of modifications would have to be made to the B&B, or if I go this way, should I just get headers, bullet cats, and B&B mufflers? Please note that this vehicle must pass emissions is TX.
3) Assuming I go with an LT1, what kind of undertaking is it to change out roller rockers, springs, etc, as well as cams?
4) LT1 - how much should it cost to have the heads CNC machined?
LT4 - how many owners port stock LT4 heads?
5) Assuming I do none of the above (except maybe exhaust), what all is invovled in building a 383 stroker? ie what parts must be replaced, or are we talking about a completely new engine?
6) What kind of HP/TQ numbers should I realistically expect from an LT1 with intake, 52mm TB, ported heads, 1.6 RR, LT4 valve springs, valve grind, cams, headers, sport cats and cat-back exhaust?
7) What kind of HP/TQ numbers should I realistically expect from an LT4 with intake, 52mm TB, cams, headers, sport cats and cat-back exhaust while running STOCK heads, RR, valve springs and valve clearance?
Sorry, I know this is a rather long post with ~349582 questions in it, but any insight would be greatly appreciated; I'm still trying to figure out how I should go about building up the car, so I have alot of questions.
1) Is there any HP/TQ gain with shorty headers?
2) Long tube headers - will they work with cats and a B&B cat-back system? What sort of modifications would have to be made to the B&B, or if I go this way, should I just get headers, bullet cats, and B&B mufflers? Please note that this vehicle must pass emissions is TX.
3) Assuming I go with an LT1, what kind of undertaking is it to change out roller rockers, springs, etc, as well as cams?
4) LT1 - how much should it cost to have the heads CNC machined?
LT4 - how many owners port stock LT4 heads?
5) Assuming I do none of the above (except maybe exhaust), what all is invovled in building a 383 stroker? ie what parts must be replaced, or are we talking about a completely new engine?
6) What kind of HP/TQ numbers should I realistically expect from an LT1 with intake, 52mm TB, ported heads, 1.6 RR, LT4 valve springs, valve grind, cams, headers, sport cats and cat-back exhaust?
7) What kind of HP/TQ numbers should I realistically expect from an LT4 with intake, 52mm TB, cams, headers, sport cats and cat-back exhaust while running STOCK heads, RR, valve springs and valve clearance?
Sorry, I know this is a rather long post with ~349582 questions in it, but any insight would be greatly appreciated; I'm still trying to figure out how I should go about building up the car, so I have alot of questions.
04-24-2004, 09:49 PM
#2
Elite Torch Red Member
Re: lots of C4 performance questions (aeronautica86)
1.)no
2.)no, not without modifications
3.)haven't tried yet
4.)haven't done it yet
5.)crankshaft,rods and pistons
6.)I've seen many different results
7.)A lot more than the LT1
2.)no, not without modifications
3.)haven't tried yet
4.)haven't done it yet
5.)crankshaft,rods and pistons
6.)I've seen many different results
7.)A lot more than the LT1
04-24-2004, 09:56 PM
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Re: lots of C4 performance questions (aeronautica86)
Gains from shorties are about half of what comes from longtubes. Id figure 5-7hp, similar torque. Not worth the expense. Cutting and welding will be necessary for fitment of longtubes on a LT though, you certainly cant stick with the stock cats.
Most port jobs run between 500-1000, depending on who does it and what you have done.
For a 383, you just need the block bored 030" and a stroker 3.75" crank.
Most port jobs run between 500-1000, depending on who does it and what you have done.
For a 383, you just need the block bored 030" and a stroker 3.75" crank.
04-25-2004, 03:35 AM
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Re: lots of C4 performance questions (vader86)
Ah Vader... I think Mojo also correctly added the pistons (piston pin location change due to longer stroke)... or am I missing something... it wouldn't be the first time if I did
04-25-2004, 01:31 PM
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Re: lots of C4 performance questions (amm0bob)
EDIT, I had a brain fart.
[Modified by vader86, 3:59 PM 4/25/2004]
04-25-2004, 04:43 PM
#6
Re: lots of C4 performance questions (vader86)
You can keep the original pistons, you dont have to change those.
04-25-2004, 04:52 PM
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Re: lots of C4 performance questions (britvette)
You can keep the original pistons, you dont have to change those.
Wouldn't you need short rods if you did, else the piston would come out of the hole by that extra 1/4" of stroke ?
Wouldn't you need short rods if you did, else the piston would come out of the hole by that extra 1/4" of stroke ?
Yes you do need new pistons, the bore is going to change. You dont need new rods, but they do need to be machined.
04-26-2004, 12:49 PM
#8
Melting Slicks
Re: lots of C4 performance questions (aeronautica86)
1) Is there any HP/TQ gain with shorty headers?
I have heard others say they don't help much
2) Long tube headers - will they work with cats and a B&B cat-back system? What sort of modifications would have to be made to the B&B, or if I go this way, should I just get headers, bullet cats, and B&B mufflers? Please note that this vehicle must pass emissions is TX.
I have the B&B's w/TPIS headers, and you use the RT Bullit cats with the cat back. You will have to cut them on both sides though.
3) Assuming I go with an LT1, what kind of undertaking is it to change out roller rockers, springs, etc, as well as cams?
With the engine in the car it can be done, but it is a major pita.
4) LT1 - how much should it cost to have the heads CNC machined?
LT4 - how many owners port stock LT4 heads?
I had mine done at CNC in Florida and it was $1895 plus exchange. This included the valve train.
5) Assuming I do none of the above (except maybe exhaust), what all is invovled in building a 383 stroker? ie what parts must be replaced, or are we talking about a completely new engine?
I chose a forged rotating assembly (Callies, Oliver, JE) and also went with the 4-bolt billet main caps. You will also need a cam and probably new springs to handle the extra lift. There will be quite a bit of machine work (count on $800 - $1000). I also went with Comp Cam R series lifters, 1.6 roller rockers, chromemoly pushrods.
You get the point... you can go crazy here trying to eliminate the weakest link. You will also want to consider upgrading your clutch, and your cooling and oiling systems. New U-Joints as well.
6) What kind of HP/TQ numbers should I realistically expect from an LT1 with intake, 52mm TB, ported heads, 1.6 RR, LT4 valve springs, valve grind, cams, headers, sport cats and cat-back exhaust?
I had 350rwhp/350rwtq with a similar setup, and that was with a pretty mild cam.
7) What kind of HP/TQ numbers should I realistically expect from an LT4 with intake, 52mm TB, cams, headers, sport cats and cat-back exhaust while running STOCK heads, RR, valve springs and valve clearance?
Maybe the same as above. With ported heads, maybe another 15hp.
Mike
I have heard others say they don't help much
2) Long tube headers - will they work with cats and a B&B cat-back system? What sort of modifications would have to be made to the B&B, or if I go this way, should I just get headers, bullet cats, and B&B mufflers? Please note that this vehicle must pass emissions is TX.
I have the B&B's w/TPIS headers, and you use the RT Bullit cats with the cat back. You will have to cut them on both sides though.
3) Assuming I go with an LT1, what kind of undertaking is it to change out roller rockers, springs, etc, as well as cams?
With the engine in the car it can be done, but it is a major pita.
4) LT1 - how much should it cost to have the heads CNC machined?
LT4 - how many owners port stock LT4 heads?
I had mine done at CNC in Florida and it was $1895 plus exchange. This included the valve train.
5) Assuming I do none of the above (except maybe exhaust), what all is invovled in building a 383 stroker? ie what parts must be replaced, or are we talking about a completely new engine?
I chose a forged rotating assembly (Callies, Oliver, JE) and also went with the 4-bolt billet main caps. You will also need a cam and probably new springs to handle the extra lift. There will be quite a bit of machine work (count on $800 - $1000). I also went with Comp Cam R series lifters, 1.6 roller rockers, chromemoly pushrods.
You get the point... you can go crazy here trying to eliminate the weakest link. You will also want to consider upgrading your clutch, and your cooling and oiling systems. New U-Joints as well.
6) What kind of HP/TQ numbers should I realistically expect from an LT1 with intake, 52mm TB, ported heads, 1.6 RR, LT4 valve springs, valve grind, cams, headers, sport cats and cat-back exhaust?
I had 350rwhp/350rwtq with a similar setup, and that was with a pretty mild cam.
7) What kind of HP/TQ numbers should I realistically expect from an LT4 with intake, 52mm TB, cams, headers, sport cats and cat-back exhaust while running STOCK heads, RR, valve springs and valve clearance?
Maybe the same as above. With ported heads, maybe another 15hp.
Mike