Full Version: how to tell LT4 from LT1 heads???
okay i have an LT4 intake manifold on my car and i was told that the heads are aftermarket also so i am wondering if there is a way to tell the LT1 and LT4 heads apart..
QUOTE(91formula @ May 10 2010, 09:12 AM) 
okay i have an LT4 intake manifold on my car and i was told that the heads are aftermarket also so i am wondering if there is a way to tell the LT1 and LT4 heads apart..
these heads are on the car BTW lol theyre aluminum but i think LT1 heads are too...right?
One way is to find a serial number or some sort of ID mark on the heads (maybe under the valve cover), then call the company and ask if they are compatible with the LT4 intake. Another way is to remove the intake and physically check and measure the ports to see if the intake and heads are compatible.
105 mph in the quarter is not too shabby. A lower ET depends upon gearing and the amt of low end torque the engine can develop, also in how long it can maintain that torque thru the rpm curve. Also, can't forget the rear end gearing and the ability of getting the power to the ground via the tires (how sticky are they?).
It is possible that the heads are correct, but with a larger than stock throttlebody (a larger throttlebody decreases low end torque and slightly increases upper end torque which will affect the ET), slippery tires and a tall rear end ratio, maybe a 3.23 (these are common on Firebirds and Camaros) it will all add up to a slower than expected ET.
It's all about the combinations that are being used and what should be looked at is how much torque is the engine generating down low and how can it be increased and put to the ground? This can be done several ways. The first thing is to go back to the OEM throttlebody to raise low rpm torque. The next would be to check the rear end ratio--it should be at least a 3.42:1. Next, how sticky are the tires? Is the engine equipped with 1.6 roller rockers (these are guaranteed to produce about 15 hp and 15 ft/lbs of torque and more depending upon engine breathing and max rpm). Is the engine equipped with the Air Flow Research Hydra Rev Kit? This kit will allow the engine to rev to around 6,600 rpm and will keep the lifters on the cam to decrease the amt of hp lost to the lifers bouncing on the cam lobes. Hot cams can lose up to 100 hp at 6,000 rpm to lifter bounce. Check out AIR's website.
Your car's description states "Tune". Depending upon who did the tune, it might not be very good and could hurt the engine's performance. Most "tuners' like to get the engine to run lean at the top end--it's the wrong way to do it. Running lean at the top end on a dyno might make a few more hp, but it won't help on the street. Also, the standard computer tuning is within just a few hp of absolute max. GM did a very good job with the software. About the only thing that is needed is to raise the rpm of the fuel cutouts, esp. if the AFR Hydra Rev Kit is used.
As an aside, my car did a 12.54 thru the 1/4 and did it with a stock throttlebody. I knew one guy that put his Firbird on Nitrous and typically cut 120 mph in the 1/4--all using the stock throttlebody. The OEM TB will flow 640cfm with an airfoil and that is more than enough for any conceivable street combination. Any other size interferes with the air flow management that is programmed within the computer.
Just my .02 cents worth.
105 mph in the quarter is not too shabby. A lower ET depends upon gearing and the amt of low end torque the engine can develop, also in how long it can maintain that torque thru the rpm curve. Also, can't forget the rear end gearing and the ability of getting the power to the ground via the tires (how sticky are they?).
It is possible that the heads are correct, but with a larger than stock throttlebody (a larger throttlebody decreases low end torque and slightly increases upper end torque which will affect the ET), slippery tires and a tall rear end ratio, maybe a 3.23 (these are common on Firebirds and Camaros) it will all add up to a slower than expected ET.
It's all about the combinations that are being used and what should be looked at is how much torque is the engine generating down low and how can it be increased and put to the ground? This can be done several ways. The first thing is to go back to the OEM throttlebody to raise low rpm torque. The next would be to check the rear end ratio--it should be at least a 3.42:1. Next, how sticky are the tires? Is the engine equipped with 1.6 roller rockers (these are guaranteed to produce about 15 hp and 15 ft/lbs of torque and more depending upon engine breathing and max rpm). Is the engine equipped with the Air Flow Research Hydra Rev Kit? This kit will allow the engine to rev to around 6,600 rpm and will keep the lifters on the cam to decrease the amt of hp lost to the lifers bouncing on the cam lobes. Hot cams can lose up to 100 hp at 6,000 rpm to lifter bounce. Check out AIR's website.
Your car's description states "Tune". Depending upon who did the tune, it might not be very good and could hurt the engine's performance. Most "tuners' like to get the engine to run lean at the top end--it's the wrong way to do it. Running lean at the top end on a dyno might make a few more hp, but it won't help on the street. Also, the standard computer tuning is within just a few hp of absolute max. GM did a very good job with the software. About the only thing that is needed is to raise the rpm of the fuel cutouts, esp. if the AFR Hydra Rev Kit is used.
As an aside, my car did a 12.54 thru the 1/4 and did it with a stock throttlebody. I knew one guy that put his Firbird on Nitrous and typically cut 120 mph in the 1/4--all using the stock throttlebody. The OEM TB will flow 640cfm with an airfoil and that is more than enough for any conceivable street combination. Any other size interferes with the air flow management that is programmed within the computer.
Just my .02 cents worth.
QUOTE(Me Too @ May 10 2010, 01:00 PM)
One way is to find a serial number or some sort of ID mark on the heads (maybe under the valve cover), then call the company and ask if they are compatible with the LT4 intake. Another way is to remove the intake and physically check and measure the ports to see if the intake and heads are compatible.
105 mph in the quarter is not too shabby. A lower ET depends upon gearing and the amt of low end torque the engine can develop, also in how long it can maintain that torque thru the rpm curve. Also, can't forget the rear end gearing and the ability of getting the power to the ground via the tires (how sticky are they?).
It is possible that the heads are correct, but with a larger than stock throttlebody (a larger throttlebody decreases low end torque and slightly increases upper end torque which will affect the ET), slippery tires and a tall rear end ratio, maybe a 3.23 (these are common on Firebirds and Camaros) it will all add up to a slower than expected ET.
It's all about the combinations that are being used and what should be looked at is how much torque is the engine generating down low and how can it be increased and put to the ground? This can be done several ways. The first thing is to go back to the OEM throttlebody to raise low rpm torque. The next would be to check the rear end ratio--it should be at least a 3.42:1. Next, how sticky are the tires? Is the engine equipped with 1.6 roller rockers (these are guaranteed to produce about 15 hp and 15 ft/lbs of torque and more depending upon engine breathing and max rpm). Is the engine equipped with the Air Flow Research Hydra Rev Kit? This kit will allow the engine to rev to around 6,600 rpm and will keep the lifters on the cam to decrease the amt of hp lost to the lifers bouncing on the cam lobes. Hot cams can lose up to 100 hp at 6,000 rpm to lifter bounce. Check out AIR's website.
Your car's description states "Tune". Depending upon who did the tune, it might not be very good and could hurt the engine's performance. Most "tuners' like to get the engine to run lean at the top end--it's the wrong way to do it. Running lean at the top end on a dyno might make a few more hp, but it won't help on the street. Also, the standard computer tuning is within just a few hp of absolute max. GM did a very good job with the software. About the only thing that is needed is to raise the rpm of the fuel cutouts, esp. if the AFR Hydra Rev Kit is used.
As an aside, my car did a 12.54 thru the 1/4 and did it with a stock throttlebody. I knew one guy that put his Firbird on Nitrous and typically cut 120 mph in the 1/4--all using the stock throttlebody. The OEM TB will flow 640cfm with an airfoil and that is more than enough for any conceivable street combination. Any other size interferes with the air flow management that is programmed within the computer.
Just my .02 cents worth.
105 mph in the quarter is not too shabby. A lower ET depends upon gearing and the amt of low end torque the engine can develop, also in how long it can maintain that torque thru the rpm curve. Also, can't forget the rear end gearing and the ability of getting the power to the ground via the tires (how sticky are they?).
It is possible that the heads are correct, but with a larger than stock throttlebody (a larger throttlebody decreases low end torque and slightly increases upper end torque which will affect the ET), slippery tires and a tall rear end ratio, maybe a 3.23 (these are common on Firebirds and Camaros) it will all add up to a slower than expected ET.
It's all about the combinations that are being used and what should be looked at is how much torque is the engine generating down low and how can it be increased and put to the ground? This can be done several ways. The first thing is to go back to the OEM throttlebody to raise low rpm torque. The next would be to check the rear end ratio--it should be at least a 3.42:1. Next, how sticky are the tires? Is the engine equipped with 1.6 roller rockers (these are guaranteed to produce about 15 hp and 15 ft/lbs of torque and more depending upon engine breathing and max rpm). Is the engine equipped with the Air Flow Research Hydra Rev Kit? This kit will allow the engine to rev to around 6,600 rpm and will keep the lifters on the cam to decrease the amt of hp lost to the lifers bouncing on the cam lobes. Hot cams can lose up to 100 hp at 6,000 rpm to lifter bounce. Check out AIR's website.
Your car's description states "Tune". Depending upon who did the tune, it might not be very good and could hurt the engine's performance. Most "tuners' like to get the engine to run lean at the top end--it's the wrong way to do it. Running lean at the top end on a dyno might make a few more hp, but it won't help on the street. Also, the standard computer tuning is within just a few hp of absolute max. GM did a very good job with the software. About the only thing that is needed is to raise the rpm of the fuel cutouts, esp. if the AFR Hydra Rev Kit is used.
As an aside, my car did a 12.54 thru the 1/4 and did it with a stock throttlebody. I knew one guy that put his Firbird on Nitrous and typically cut 120 mph in the 1/4--all using the stock throttlebody. The OEM TB will flow 640cfm with an airfoil and that is more than enough for any conceivable street combination. Any other size interferes with the air flow management that is programmed within the computer.
Just my .02 cents worth.
Im going to try and get ahold of the original owner and get tto the bottom of this! i really would like to know what is done to my car, thats would help alot. and about my tires, theyre eagle f1's. ive been told theyre pretty good but idk. they seem to spin alot. i had to baby it out the hole at the track or it would spin badly. My car does hit rev limter at about almost 7k rpms. When it was ran at the track i did have my buddy drive it to run 105mph @ 13.8 because he has been driving manual cars longer (this is my first) and he weighs ALOT more than i do..i am about 180 he is about 250 atleast lol with the 2 of us and 60lbs of tools we ran a 14.1 the first pass. so deduct all the weight and i think it would have dipped lower than a 13.8 that time.
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