timing for 383 w/LT4 hotcam
04-01-2009, 05:19 PM
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timing for 383 w/LT4 hotcam Good day to all. I am currently building up a 383 in my 94 z28. The question that I have is to keep the same hotcam profile as the 350, will I need to degree my LT4 hotcam +2 deg for the 383? I have been told that the Hotcam is to mild for the 383, but I have also been told by a few professional race motor builders is if I advance it +2 degrees then it will keep the same profile. Has anyone here built a 383 stroker with an LT4 Hotcam? I had it installed in my engine for two months before I spun a main bearing.
Now here is all the specs for the engine that is being built: The bottom end is a 383 with made by scat. It is all forged with 6" I beam rods clearanced for a normal base cam. The pistons are dish pistons to keep the 10.4-1 compression ratio. I have Crain Gold 1.6 rollor rockers mounted on stock fully ported an polished heads with a five angle valve job (heads are not milled). The intake is a fully ported stock intake with a BBK 58mm throttle body. I also have an oversized MAF and Dynatech long tube headers.
I hope that I have provided enough information to get the answer that I am looking for. I hope that someone here has built a similar motor with a 383 with an LT4 Hotcam. Also any guesses as to what kind of rwhp I am looking at when I am done. Oh the trans is a t-56 with a new SouthBend Clutch. I thank you all for looking a welcome any positive comments.
Now here is all the specs for the engine that is being built: The bottom end is a 383 with made by scat. It is all forged with 6" I beam rods clearanced for a normal base cam. The pistons are dish pistons to keep the 10.4-1 compression ratio. I have Crain Gold 1.6 rollor rockers mounted on stock fully ported an polished heads with a five angle valve job (heads are not milled). The intake is a fully ported stock intake with a BBK 58mm throttle body. I also have an oversized MAF and Dynatech long tube headers.
I hope that I have provided enough information to get the answer that I am looking for. I hope that someone here has built a similar motor with a 383 with an LT4 Hotcam. Also any guesses as to what kind of rwhp I am looking at when I am done. Oh the trans is a t-56 with a new SouthBend Clutch. I thank you all for looking a welcome any positive comments.
04-01-2009, 05:25 PM
#2
Good day to all. I am currently building up a 383 in my 94 z28. The question that I have is to keep the same hotcam profile as the 350, will I need to degree my LT4 hotcam +2 deg for the 383? I have been told that the Hotcam is to mild for the 383, but I have also been told by a few professional race motor builders is if I advance it +2 degrees then it will keep the same profile. Has anyone here built a 383 stroker with an LT4 Hotcam? I had it installed in my engine for two months before I spun a main bearing.
Now here is all the specs for the engine that is being built: The bottom end is a 383 with made by scat. It is all forged with 6" I beam rods clearanced for a normal base cam. The pistons are dish pistons to keep the 10.4-1 compression ratio. I have Crain Gold 1.6 rollor rockers mounted on stock fully ported an polished heads with a five angle valve job (heads are not milled). The intake is a fully ported stock intake with a BBK 58mm throttle body. I also have an oversized MAF and Dynatech long tube headers.
I hope that I have provided enough information to get the answer that I am looking for. I hope that someone here has built a similar motor with a 383 with an LT4 Hotcam. Also any guesses as to what kind of rwhp I am looking at when I am done. Oh the trans is a t-56 with a new SouthBend Clutch. I thank you all for looking a welcome any positive comments.
Now here is all the specs for the engine that is being built: The bottom end is a 383 with made by scat. It is all forged with 6" I beam rods clearanced for a normal base cam. The pistons are dish pistons to keep the 10.4-1 compression ratio. I have Crain Gold 1.6 rollor rockers mounted on stock fully ported an polished heads with a five angle valve job (heads are not milled). The intake is a fully ported stock intake with a BBK 58mm throttle body. I also have an oversized MAF and Dynatech long tube headers.
I hope that I have provided enough information to get the answer that I am looking for. I hope that someone here has built a similar motor with a 383 with an LT4 Hotcam. Also any guesses as to what kind of rwhp I am looking at when I am done. Oh the trans is a t-56 with a new SouthBend Clutch. I thank you all for looking a welcome any positive comments.
04-01-2009, 05:33 PM
#3
Good day to all. I am currently building up a 383 in my 94 z28. The question that I have is to keep the same hotcam profile as the 350, will I need to degree my LT4 hotcam +2 deg for the 383? I have been told that the Hotcam is to mild for the 383, but I have also been told by a few professional race motor builders is if I advance it +2 degrees then it will keep the same profile. Has anyone here built a 383 stroker with an LT4 Hotcam? I had it installed in my engine for two months before I spun a main bearing.
Now here is all the specs for the engine that is being built: The bottom end is a 383 with made by scat. It is all forged with 6" I beam rods clearanced for a normal base cam. The pistons are dish pistons to keep the 10.4-1 compression ratio. I have Crain Gold 1.6 rollor rockers mounted on stock fully ported an polished heads with a five angle valve job (heads are not milled). The intake is a fully ported stock intake with a BBK 58mm throttle body. I also have an oversized MAF and Dynatech long tube headers.
I hope that I have provided enough information to get the answer that I am looking for. I hope that someone here has built a similar motor with a 383 with an LT4 Hotcam. Also any guesses as to what kind of rwhp I am looking at when I am done. Oh the trans is a t-56 with a new SouthBend Clutch. I thank you all for looking a welcome any positive comments.
Now here is all the specs for the engine that is being built: The bottom end is a 383 with made by scat. It is all forged with 6" I beam rods clearanced for a normal base cam. The pistons are dish pistons to keep the 10.4-1 compression ratio. I have Crain Gold 1.6 rollor rockers mounted on stock fully ported an polished heads with a five angle valve job (heads are not milled). The intake is a fully ported stock intake with a BBK 58mm throttle body. I also have an oversized MAF and Dynatech long tube headers.
I hope that I have provided enough information to get the answer that I am looking for. I hope that someone here has built a similar motor with a 383 with an LT4 Hotcam. Also any guesses as to what kind of rwhp I am looking at when I am done. Oh the trans is a t-56 with a new SouthBend Clutch. I thank you all for looking a welcome any positive comments.
Get rid of the "oversized MAF." It will only make your car harder to tune and can be the source of many issues you'll never solve. Also, don't use the hotcam.
You should have the cam degreed within the ICL on the cam card. Almost all LT1 cams have several degrees of advance ground into them already, including the LT4 (which you shouldn't use).
10.4:1 compression is very low for an LT1 383. You're running less compression than stock - you'll definitely take a hit on performance. Most 383s nowadays (that aren't built for N2O or boost) are well upwards of 11.0:1 (mine is pushing well past 12.0:1). I am using -5cc flat-tops with milled heads, zero decked block, and a .026" head gasket. Also, don't use the hotcam.
With your setup, as is, with the hotcam, I wouldn't expect more than ~360whp, and that might even be pushing it, especially without knowing any other statistics about the heads. Not to mention, don't use the hotcam.
04-01-2009, 05:38 PM
#4
Honestly you've got some mismatched parts. Using the hotcam on a 383 is a very poor performance choice. Aside from a custom grind (best case scenario, look into it from AI or LE), there are MUCH better off-the-shelf cams that would work MUCH better than the dated technology the hotcam has to offer. So don't use the hotcam.
Get rid of the "oversized MAF." It will only make your car harder to tune and can be the source of many issues you'll never solve. Also, don't use the hotcam.
You should have the cam degreed within the ICL on the cam card. Almost all LT1 cams have several degrees of advance ground into them already, including the LT4 (which you shouldn't use).
10.4:1 compression is very low for an LT1 383. You're running less compression than stock - you'll definitely take a hit on performance. Most 383s nowadays (that aren't built for N2O or boost) are well upwards of 11.0:1 (mine is pushing well past 12.0:1). I am using -5cc flat-tops with milled heads, zero decked block, and a .026" head gasket. Also, don't use the hotcam.
With your setup, as is, with the hotcam, I wouldn't expect more than ~360whp, and that might even be pushing it, especially without knowing any other statistics about the heads. Not to mention, don't use the hotcam.
Get rid of the "oversized MAF." It will only make your car harder to tune and can be the source of many issues you'll never solve. Also, don't use the hotcam.
You should have the cam degreed within the ICL on the cam card. Almost all LT1 cams have several degrees of advance ground into them already, including the LT4 (which you shouldn't use).
10.4:1 compression is very low for an LT1 383. You're running less compression than stock - you'll definitely take a hit on performance. Most 383s nowadays (that aren't built for N2O or boost) are well upwards of 11.0:1 (mine is pushing well past 12.0:1). I am using -5cc flat-tops with milled heads, zero decked block, and a .026" head gasket. Also, don't use the hotcam.
With your setup, as is, with the hotcam, I wouldn't expect more than ~360whp, and that might even be pushing it, especially without knowing any other statistics about the heads. Not to mention, don't use the hotcam.
04-01-2009, 05:54 PM
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Honestly you've got some mismatched parts. Using the hotcam on a 383 is a very poor performance choice. Aside from a custom grind (best case scenario, look into it from AI or LE), there are MUCH better off-the-shelf cams that would work MUCH better than the dated technology the hotcam has to offer. So don't use the hotcam.
Get rid of the "oversized MAF." It will only make your car harder to tune and can be the source of many issues you'll never solve. Also, don't use the hotcam.
You should have the cam degreed within the ICL on the cam card. Almost all LT1 cams have several degrees of advance ground into them already, including the LT4 (which you shouldn't use).
10.4:1 compression is very low for an LT1 383. You're running less compression than stock - you'll definitely take a hit on performance. Most 383s nowadays (that aren't built for N2O or boost) are well upwards of 11.0:1 (mine is pushing well past 12.0:1). I am using -5cc flat-tops with milled heads, zero decked block, and a .026" head gasket. Also, don't use the hotcam.
With your setup, as is, with the hotcam, I wouldn't expect more than ~360whp, and that might even be pushing it, especially without knowing any other statistics about the heads. Not to mention, don't use the hotcam.
Get rid of the "oversized MAF." It will only make your car harder to tune and can be the source of many issues you'll never solve. Also, don't use the hotcam.
You should have the cam degreed within the ICL on the cam card. Almost all LT1 cams have several degrees of advance ground into them already, including the LT4 (which you shouldn't use).
10.4:1 compression is very low for an LT1 383. You're running less compression than stock - you'll definitely take a hit on performance. Most 383s nowadays (that aren't built for N2O or boost) are well upwards of 11.0:1 (mine is pushing well past 12.0:1). I am using -5cc flat-tops with milled heads, zero decked block, and a .026" head gasket. Also, don't use the hotcam.
With your setup, as is, with the hotcam, I wouldn't expect more than ~360whp, and that might even be pushing it, especially without knowing any other statistics about the heads. Not to mention, don't use the hotcam.
Also about the compression, the stock LT1's came with 10.4-1 compression ratio. I did a lot of research before I bought the kit. If I would have got the kit with flat top pistions then with the stock ported heads, then I would have been pushing upward of 11.3-1 compression ratio. That would mean that I would be looking at very high octane fuel all the time. Also about the maf sensor, why has everyone been telling me that I should put the stock one back on? Has there been some major issues with these? I have yet to have any issues with mine. I bought the car with it installed and I still have the stock one.
Anyway, thank you for your replies. And I am seeing, don't use the hotcam.
04-01-2009, 05:58 PM
#7
Well I think I can see where you are going about using the hotcam. The only reason why I wanted to use the hotcam is because I just installed it 3 months ago and loved the way that it performed. I was running through options and I had someone who builds race engines for proffessional racing and he told me to just keep the cam in it and degree it +2 degrees. This is why I am seeking advice from some people other people. Is there a cam that will give the 383 the same performace as the LT4 hotcam did in the 350.
Also about the compression, the stock LT1's came with 10.4-1 compression ratio. I did a lot of research before I bought the kit. If I would have got the kit with flat top pistions then with the stock ported heads, then I would have been pushing upward of 11.3-1 compression ratio. That would mean that I would be looking at very high octane fuel all the time. Also about the maf sensor, why has everyone been telling me that I should put the stock one back on? Has there been some major issues with these? I have yet to have any issues with mine. I bought the car with it installed and I still have the stock one.
Anyway, thank you for your replies. And I am seeing, don't use the hotcam.
Also about the compression, the stock LT1's came with 10.4-1 compression ratio. I did a lot of research before I bought the kit. If I would have got the kit with flat top pistions then with the stock ported heads, then I would have been pushing upward of 11.3-1 compression ratio. That would mean that I would be looking at very high octane fuel all the time. Also about the maf sensor, why has everyone been telling me that I should put the stock one back on? Has there been some major issues with these? I have yet to have any issues with mine. I bought the car with it installed and I still have the stock one.
Anyway, thank you for your replies. And I am seeing, don't use the hotcam.
If you wanted a mild performing 383, then I would get something like a CC503 at the min for your car.
Just saying that I've read different.
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04-01-2009, 06:02 PM
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LT1 Engine Block, Fuel, Valvetrain & Power Specs
Block Specs
Displacement: 350 cubic inches, 5733 cubic centimeters, 5.7 liters
Block Material: Cast Iron
Main Bearings: 2-Bolt Centers and Ends (The Corvette LT1/LT4 had 4-bolt mains)
Stroke: 3.48″
Bore: 4.00″
Compression Ratio: 10.4:1
Combustion Chambers: 54 cubic centimeters
Factory Redline Rating: 5700 Rotations Per Minute
Bottom End
Piston Material: (10159437) Eutectic Aluminum/Silicon Alloy
Connecting Rod Material: (10108688) Powdered Metal
Crankshaft Material: (12556307) Cast Iron
Top End and Valvetrain
Cylinder Heads: (10168448) Cast Aluminum, 2 valves per cylinder/16 valves total, ~212 CFM flow (Impala SS and
Caprice heads were made of cast iron*)
Valve Diameter: (intake- 10241743, exhaust- 12550909) 1.94 intake, 1.50 exhaust
Valve Overlap: 41*
Valvesprings: (10206040) 85 lbs, seated
Camshaft Specs (12551705): 205/207 duration @ 50*, .447/.459″ lift, 117 Lobe Seperation Angle
Rocker Arms: (10089648) 1.5:1 Stamped Steel
Timing Chain: (10128485) Powdered metal butt link
Intake and Fuel Delivery
Fuel Delivery: Electronic Fuel Injection, sequential port
Injector Size: (17124248) 3.0gps, 22lbs/hr speed density (1992-1993), 24lbs/hr mass airflow (1994-1997)
Throttle Body: 48 millimeter twin butterfly
Intake Manifold: (12552137) Aluminum
Factory Power Ratings
92-96 LT1 Corvette: 300bhp, 330lb-ft
1996 LT4 Corvette: 330bhp, 340lb-ft
1992 LT5 Corvette: 375bhp, 370lb-ft
93-95 LT5 Corvette: 405bhp, 385lb-ft
93-95 LT1 F-Body: 275bhp, 325lb-ft
96-97 LT1 F-Body: 285bhp, 325lb-ft
96-97 WS6/SS: 305bhp, 335lb-ft
93-97 Firehawks: 315bhp, 340lb-ft
Factory Camshaft Specifications:
1992 Y-body: 205/207 0.451/0.450 lift 117 LSA
1993-1995 Y-body, F-body: 202/207 0.450/0.460 lift 116 LSA
1994-1996 B-bodies (including L99 4.3L): 191/196 0.418/0.430 lift 111 LSA
1996 Y-body, 1996-1997 F-body: 200/207 0.447/0.459 lift 117 LSA
1996 Y-body, F-body LT4: 203/210 0.476/0.479 lift 115 LSA
Cylinder Head Flow Data*
Edelbrock
Lift Intake Exhaust
.100 61 52
.200 117 100
.300 174 140
.400 220 167
.500 242 184
.600 232 192
Stock LT1
Lift Intake Exhaust
.100 64 45
.200 127 93
.300 179 127
.400 214 145
.500 226 156
GM LT4
Lift Intake Exhaust
.100 N/A N/A
.200 156 121
.300 208 149
.400 243 177
.500 265 190
.600 257 196
*All flow data is at 28 inches of H2O with a radiused intake and no exhaust extension.
See http://www.lt1engine.com/tech/lt1-en...n-power-specs/ for reference. This information can also be found on Chiltons and Haynes.
Block Specs
Displacement: 350 cubic inches, 5733 cubic centimeters, 5.7 liters
Block Material: Cast Iron
Main Bearings: 2-Bolt Centers and Ends (The Corvette LT1/LT4 had 4-bolt mains)
Stroke: 3.48″
Bore: 4.00″
Compression Ratio: 10.4:1
Combustion Chambers: 54 cubic centimeters
Factory Redline Rating: 5700 Rotations Per Minute
Bottom End
Piston Material: (10159437) Eutectic Aluminum/Silicon Alloy
Connecting Rod Material: (10108688) Powdered Metal
Crankshaft Material: (12556307) Cast Iron
Top End and Valvetrain
Cylinder Heads: (10168448) Cast Aluminum, 2 valves per cylinder/16 valves total, ~212 CFM flow (Impala SS and
Caprice heads were made of cast iron*)
Valve Diameter: (intake- 10241743, exhaust- 12550909) 1.94 intake, 1.50 exhaust
Valve Overlap: 41*
Valvesprings: (10206040) 85 lbs, seated
Camshaft Specs (12551705): 205/207 duration @ 50*, .447/.459″ lift, 117 Lobe Seperation Angle
Rocker Arms: (10089648) 1.5:1 Stamped Steel
Timing Chain: (10128485) Powdered metal butt link
Intake and Fuel Delivery
Fuel Delivery: Electronic Fuel Injection, sequential port
Injector Size: (17124248) 3.0gps, 22lbs/hr speed density (1992-1993), 24lbs/hr mass airflow (1994-1997)
Throttle Body: 48 millimeter twin butterfly
Intake Manifold: (12552137) Aluminum
Factory Power Ratings
92-96 LT1 Corvette: 300bhp, 330lb-ft
1996 LT4 Corvette: 330bhp, 340lb-ft
1992 LT5 Corvette: 375bhp, 370lb-ft
93-95 LT5 Corvette: 405bhp, 385lb-ft
93-95 LT1 F-Body: 275bhp, 325lb-ft
96-97 LT1 F-Body: 285bhp, 325lb-ft
96-97 WS6/SS: 305bhp, 335lb-ft
93-97 Firehawks: 315bhp, 340lb-ft
Factory Camshaft Specifications:
1992 Y-body: 205/207 0.451/0.450 lift 117 LSA
1993-1995 Y-body, F-body: 202/207 0.450/0.460 lift 116 LSA
1994-1996 B-bodies (including L99 4.3L): 191/196 0.418/0.430 lift 111 LSA
1996 Y-body, 1996-1997 F-body: 200/207 0.447/0.459 lift 117 LSA
1996 Y-body, F-body LT4: 203/210 0.476/0.479 lift 115 LSA
Cylinder Head Flow Data*
Edelbrock
Lift Intake Exhaust
.100 61 52
.200 117 100
.300 174 140
.400 220 167
.500 242 184
.600 232 192
Stock LT1
Lift Intake Exhaust
.100 64 45
.200 127 93
.300 179 127
.400 214 145
.500 226 156
GM LT4
Lift Intake Exhaust
.100 N/A N/A
.200 156 121
.300 208 149
.400 243 177
.500 265 190
.600 257 196
*All flow data is at 28 inches of H2O with a radiused intake and no exhaust extension.
See http://www.lt1engine.com/tech/lt1-en...n-power-specs/ for reference. This information can also be found on Chiltons and Haynes.
04-01-2009, 06:02 PM
#9
Well I think I can see where you are going about using the hotcam. The only reason why I wanted to use the hotcam is because I just installed it 3 months ago and loved the way that it performed. I was running through options and I had someone who builds race engines for proffessional racing and he told me to just keep the cam in it and degree it +2 degrees. This is why I am seeking advice from some people other people. Is there a cam that will give the 383 the same performace as the LT4 hotcam did in the 350.
Also about the compression, the stock LT1's came with 10.4-1 compression ratio. I did a lot of research before I bought the kit. If I would have got the kit with flat top pistions then with the stock ported heads, then I would have been pushing upward of 11.3-1 compression ratio. That would mean that I would be looking at very high octane fuel all the time. Also about the maf sensor, why has everyone been telling me that I should put the stock one back on? Has there been some major issues with these? I have yet to have any issues with mine. I bought the car with it installed and I still have the stock one.
Anyway, thank you for your replies. And I am seeing, don't use the hotcam.
Also about the compression, the stock LT1's came with 10.4-1 compression ratio. I did a lot of research before I bought the kit. If I would have got the kit with flat top pistions then with the stock ported heads, then I would have been pushing upward of 11.3-1 compression ratio. That would mean that I would be looking at very high octane fuel all the time. Also about the maf sensor, why has everyone been telling me that I should put the stock one back on? Has there been some major issues with these? I have yet to have any issues with mine. I bought the car with it installed and I still have the stock one.
Anyway, thank you for your replies. And I am seeing, don't use the hotcam.
However, keep in mind that SCR is just an arbitrary number, dynamic compression is the key. Do not let anything above 11.0:1 static scare you away from your build.
You won't find a cam that will perform as well as the 350 did - ANY newer grind will perform better. Strokers need duration, and the hotcam just won't cut it.
Aftermarket MAFs are difficult to tune. You WILL need a new tune once you're all said and done. Most tuners prefer stock MAFs - I would swap it back in.
Originally Posted by From the "Rebuilding the Chevrolet LT1 Engine Article
GM Powertrain accomplished all of this by reverse cooling the engine so they could bump the compression ratio up to 10.5 to 1, tweaking the airflow in and out of the engine, and using sophisticated electronic controls for both fuel and ignition. This combination gave the LT1 300 hp in 1992 and ultimately led to the 1996 LT4 that used better heads, more cam timing, roller rockers and sequential fuel injection to make 330 hp .
Thanks for providing me with that data though, but I've had it bookmarked for years.
Last edited by RamAir95TA; 04-01-2009 at 06:08 PM.
04-01-2009, 06:09 PM
#10
Well I think I can see where you are going about using the hotcam. The only reason why I wanted to use the hotcam is because I just installed it 3 months ago and loved the way that it performed. I was running through options and I had someone who builds race engines for proffessional racing and he told me to just keep the cam in it and degree it +2 degrees. This is why I am seeking advice from some people other people. Is there a cam that will give the 383 the same performace as the LT4 hotcam did in the 350.
Also about the compression, the stock LT1's came with 10.4-1 compression ratio. I did a lot of research before I bought the kit. If I would have got the kit with flat top pistions then with the stock ported heads, then I would have been pushing upward of 11.3-1 compression ratio. That would mean that I would be looking at very high octane fuel all the time. Also about the maf sensor, why has everyone been telling me that I should put the stock one back on? Has there been some major issues with these? I have yet to have any issues with mine. I bought the car with it installed and I still have the stock one.
Anyway, thank you for your replies. And I am seeing, don't use the hotcam.
Also about the compression, the stock LT1's came with 10.4-1 compression ratio. I did a lot of research before I bought the kit. If I would have got the kit with flat top pistions then with the stock ported heads, then I would have been pushing upward of 11.3-1 compression ratio. That would mean that I would be looking at very high octane fuel all the time. Also about the maf sensor, why has everyone been telling me that I should put the stock one back on? Has there been some major issues with these? I have yet to have any issues with mine. I bought the car with it installed and I still have the stock one.
Anyway, thank you for your replies. And I am seeing, don't use the hotcam.
In this day and age you can run 11.3 compersion on pump gas all day long, I dont know were you got that info from were you cant.
Aftermarket mass air flow sensors that are out for LT1s are over priced junk
04-01-2009, 06:12 PM
#11
Also what do your heads flow?
Putting a big cam into a low compresion 383 isnt going to be a good idea....
You have to rember cubes help make power, but making power lies in the cylinder heads! Without good flowing heads your not going to make the flow that big cubes need!
That aside if you have a set of mild heads, then its not going to like high rpm and the fact its a low compresion motor.
So you have to get a cam that makes power for the rpm and head flow you have, you really did limit your self by your parts selection for this motor.
Putting a big cam into a low compresion 383 isnt going to be a good idea....
You have to rember cubes help make power, but making power lies in the cylinder heads! Without good flowing heads your not going to make the flow that big cubes need!
That aside if you have a set of mild heads, then its not going to like high rpm and the fact its a low compresion motor.
So you have to get a cam that makes power for the rpm and head flow you have, you really did limit your self by your parts selection for this motor.
04-01-2009, 06:23 PM
#12
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An LT1 can handle 11.3:1 SCR without so much as a sneeze. You could run 11.3:1 on 89 octane if you really wanted to. I don't know about you, but I'm not about to let fuel octane dictate my build, hence why I'm well above 12.0:1 that will run just fine on standard 93 octane.
However, keep in mind that SCR is just an arbitrary number, dynamic compression is the key. Do not let anything above 11.0:1 static scare you away from your build.
You won't find a cam that will perform as well as the 350 did - ANY newer grind will perform better. Strokers need duration, and the hotcam just won't cut it.
Aftermarket MAFs are difficult to tune. You WILL need a new tune once you're all said and done. Most tuners prefer stock MAFs - I would swap it back in.
I'm not going to argue over 1/10th of a point, to be honest. You are not benefiting yourself by maintaining stock/less than stock compression on a performance rebuild.
Thanks for providing me with that data though, but I've had it bookmarked for years.
However, keep in mind that SCR is just an arbitrary number, dynamic compression is the key. Do not let anything above 11.0:1 static scare you away from your build.
You won't find a cam that will perform as well as the 350 did - ANY newer grind will perform better. Strokers need duration, and the hotcam just won't cut it.
Aftermarket MAFs are difficult to tune. You WILL need a new tune once you're all said and done. Most tuners prefer stock MAFs - I would swap it back in.
I'm not going to argue over 1/10th of a point, to be honest. You are not benefiting yourself by maintaining stock/less than stock compression on a performance rebuild.
Thanks for providing me with that data though, but I've had it bookmarked for years.
BTW what is SCR? Sorry I am not that good with acronyms. Also any ideas about cam options? I know the hotcam had a nasty lobe and a good mid to high end for performance. That is what I am wanting to keep. Maybe I will call Summit and get some ideas. Thank you all again for your responses. Oh I forgot to list the last thing that I have already got for the new buildup. I got a MSD Opti unit. I watched a friend blow up too many stock ones on the strip and he never had another problem after putting in the MSD in his. Thank you again.
04-01-2009, 06:28 PM
#13
I have no problem with running 93 octane fuel, that is all I ran after I built the 350 up and had it tuned. I called around a few places before ordering my kit and the all told me that I would only be able to run racing fuel using the stock heads for the build. From what was explain, was that stock heads have 64cc heads and most aftermarket heads have 54cc chambers on them. So I was advised to go with dish pistons to retain the 10.4:1 compression and use 93 octane fuel, which I do not have a problem again using. Now I am contiplating on milling the heads to zero, how much compression will I will be looking at them? Again these heads are fully ported and polished heads with a five angle valve job and flow very well.
BTW what is SCR? Sorry I am not that good with acronyms. Also any ideas about cam options? I know the hotcam had a nasty lobe and a good mid to high end for performance. That is what I am wanting to keep. Maybe I will call Summit and get some ideas. Thank you all again for your responses. Oh I forgot to list the last thing that I have already got for the new buildup. I got a MSD Opti unit. I watched a friend blow up too many stock ones on the strip and he never had another problem after putting in the MSD in his. Thank you again.
BTW what is SCR? Sorry I am not that good with acronyms. Also any ideas about cam options? I know the hotcam had a nasty lobe and a good mid to high end for performance. That is what I am wanting to keep. Maybe I will call Summit and get some ideas. Thank you all again for your responses. Oh I forgot to list the last thing that I have already got for the new buildup. I got a MSD Opti unit. I watched a friend blow up too many stock ones on the strip and he never had another problem after putting in the MSD in his. Thank you again.
DCR (dynamic compression ratio) is a much more important number. You will have to talk to the person you are getting your custom cam from (
) about that. I'd call up Ai and order ALL of your parts from the, after a long in-depth conversation.
04-01-2009, 06:31 PM
#14
I have no problem with running 93 octane fuel, that is all I ran after I built the 350 up and had it tuned. I called around a few places before ordering my kit and the all told me that I would only be able to run racing fuel using the stock heads for the build. From what was explain, was that stock heads have 64cc heads and most aftermarket heads have 54cc chambers on them. So I was advised to go with dish pistons to retain the 10.4:1 compression and use 93 octane fuel, which I do not have a problem again using. Now I am contiplating on milling the heads to zero, how much compression will I will be looking at them? Again these heads are fully ported and polished heads with a five angle valve job and flow very well.
BTW what is SCR? Sorry I am not that good with acronyms. Also any ideas about cam options? I know the hotcam had a nasty lobe and a good mid to high end for performance. That is what I am wanting to keep. Maybe I will call Summit and get some ideas. Thank you all again for your responses. Oh I forgot to list the last thing that I have already got for the new buildup. I got a MSD Opti unit. I watched a friend blow up too many stock ones on the strip and he never had another problem after putting in the MSD in his. Thank you again.
BTW what is SCR? Sorry I am not that good with acronyms. Also any ideas about cam options? I know the hotcam had a nasty lobe and a good mid to high end for performance. That is what I am wanting to keep. Maybe I will call Summit and get some ideas. Thank you all again for your responses. Oh I forgot to list the last thing that I have already got for the new buildup. I got a MSD Opti unit. I watched a friend blow up too many stock ones on the strip and he never had another problem after putting in the MSD in his. Thank you again.
SCR means static compression ratio. DCR is dynamic compression ratio.
Without knowing how well your heads flow, it's impossible to optimize a cam selection for you. But to give you an example, my custom cam for my heads (AI ported stock castings) and 383 is in the high 230s, mid 240s, on a 108 lobe, around .60x" lift. A similar grind (XE236) is in my sig if you like audio.
I would not bother calling Summit as it is unlikely they have someone in their tech department who is familiar enough with LT1s to offer you sound advice. You can get better advice from calling AI or LE. They will be happy to advise your build.
What dish is your piston?
And I hate to burst your bubble, but it seems to be hit and miss with the MSD optispark. Others have luck, many don't. Most agree you can't go wrong with an AC Delco though.
04-01-2009, 06:31 PM
#15
Who are you talking to? That is giving you this info?
You can even run 12.1 or more compression with 93!
Lt1s also have different cylinder heads that let them run higher compression on pump gas that a older SBC head.
Somone who can properly tune a EFI car would have no problem getting it to run right on it.
Static compression ratio=SCR
Please call these people and stop dealing with who is giving you miss info
http://www.advancedinduction.com/AiContact.html
http://www.ls1speed.com/
http://www.elliottsportworks.com/contact.html
You can even run 12.1 or more compression with 93!
One of the greatest features of the '92 and up Chevrolet LT1 engine is the reverse flow cooling system. In fact it is reverse flow cooling that is truly the key to the incredible performance of the modern LT1. Reverse flow cooling is vastly superior to the conventional cooling systems used on virtually all other engines. This is because it cools the cylinder heads first, preventing detonation and allowing for a much higher compression ratio and more spark advance on a given grade of gasoline. A fringe benefit is that cylinder bore temperatures are higher and more uniform, which reduces piston ring friction. Because of this new cooling system, the LT1 can easily meet ever increasing emissions standards with significant gains in power, durability, and reliability.
Lt1s also have different cylinder heads that let them run higher compression on pump gas that a older SBC head.
Somone who can properly tune a EFI car would have no problem getting it to run right on it.
Static compression ratio=SCR
Please call these people and stop dealing with who is giving you miss info
http://www.advancedinduction.com/AiContact.html
http://www.ls1speed.com/
http://www.elliottsportworks.com/contact.html
04-01-2009, 09:00 PM
#16
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I had a hotcammed 383... I had a mail order tune from pcmforless. I needed a retune (really lean up top) and it had a couple fuel leaks by the fuel pressure regulator, and had a miss uptop and made 330/390 at the wheels.
04-01-2009, 10:07 PM
#19
Teching In
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Thank you all for your responses,. It appears that I need to return my dish pistons and get regular flat tops with valve releafs and get a new cam. Now the quest is what cam to get that will match the LT4 profile that worked on the 350 for the 383. I will have to get with the machinest that did my heads to find out what my heads were flowing. I have forgotten what he said they did. I do remember that it was a remarkably high number. I had never driven a car with such good throttle response until I got my head work done and installed. Any more good suggestions are welcome as well. I want to make sure that I build this right the first time around. Thank you again.
04-01-2009, 11:41 PM
#20
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Honestly, I'd go for a bigger cam. I would now while my engine is apart but i'm too broke. I'm just a little dissapointed. I never intended for it to be a 383, i started with just a hotcam.