HP vs LBS
02-21-2011, 02:26 AM
#1
HP vs LBS Going from an aluminum ls1 to an iron lq9 how much HP is needed on the lq9 to make up for that 88lbs added to the nose of an fbody?
There should be some point where its all positive for the quarter mile.
I have read where the extra cubes give about 20RWHP thru the powerband.
this is comparing with all bolt ons.... and a big 24x/24x cam....
There should be some point where its all positive for the quarter mile.
I have read where the extra cubes give about 20RWHP thru the powerband.
this is comparing with all bolt ons.... and a big 24x/24x cam....
02-21-2011, 06:53 AM
#2
Typically every 100 lbs of static weight is generally worth 1 tenth, give or take and depending what race weight the car is at and what power it has. Also my exp tells me every 10 hp or so increase lowers ET by approx 1 tenth.
Long story off the short is yes, adding weight sucks but through out the majority of automotive history, many fast cars ran on Iron blocks. The "heavier" iron small block is the LSx block, those are the ones that weigh a ton and people out there need to make a decision about the added weight vs performance goals.
Long story off the short is yes, adding weight sucks but through out the majority of automotive history, many fast cars ran on Iron blocks. The "heavier" iron small block is the LSx block, those are the ones that weigh a ton and people out there need to make a decision about the added weight vs performance goals.
02-21-2011, 10:54 AM
#3
I did a lot of searching before posting the question and what you said is EXACTLY whats all over the boards.
Its almost a wash the only other thing I found that where the weight is can hurt a bit and having it on the front usually hurts so its basically a wash unless you net 25 hp or more. Which could very well happen.
Its almost a wash the only other thing I found that where the weight is can hurt a bit and having it on the front usually hurts so its basically a wash unless you net 25 hp or more. Which could very well happen.
Typically every 100 lbs of static weight is generally worth 1 tenth, give or take and depending what race weight the car is at and what power it has. Also my exp tells me every 10 hp or so increase lowers ET by approx 1 tenth.
Long story off the short is yes, adding weight sucks but through out the majority of automotive history, many fast cars ran on Iron blocks. The "heavier" iron small block is the LSx block, those are the ones that weigh a ton and people out there need to make a decision about the added weight vs performance goals.
Long story off the short is yes, adding weight sucks but through out the majority of automotive history, many fast cars ran on Iron blocks. The "heavier" iron small block is the LSx block, those are the ones that weigh a ton and people out there need to make a decision about the added weight vs performance goals.
02-21-2011, 11:15 AM
#4
Basically from my understand has always been that there is a trade off and with the advent of using factory Aluminum Blocks has added another varible where weight is taken off the front end of the car and at this point its almost "taken for granted" and where if you say "Hey I have a Iron Block Car" People almost look at you with a 3rd eye. Even worse so if your running iron heads and not for a specified reason i.e. LT1 Impalas.
If BUDGET can support there are plenty of benefits of sticking with a lighter block. In most cases stock block (not saying internals) can support a good amount of power before worrying about core shift or surviveability.
If the average race car was willing to sacrifice certain creature comforts to help offset the iron block then IMO its worth it. BUT Race weight is a key factor and if your RW w/ Driver is over 4000 lbs, then adding a iron block is not doing to do you any good and if your making 600-900 hp set up your just going to shred drive train parts if your looking to put down at min a 1.4x 60 foot or faster. So basically each person needs to define their goals and what they are willing to give up.
I am at that point so I know all about this.
If BUDGET can support there are plenty of benefits of sticking with a lighter block. In most cases stock block (not saying internals) can support a good amount of power before worrying about core shift or surviveability.
If the average race car was willing to sacrifice certain creature comforts to help offset the iron block then IMO its worth it. BUT Race weight is a key factor and if your RW w/ Driver is over 4000 lbs, then adding a iron block is not doing to do you any good and if your making 600-900 hp set up your just going to shred drive train parts if your looking to put down at min a 1.4x 60 foot or faster. So basically each person needs to define their goals and what they are willing to give up.
I am at that point so I know all about this.
02-21-2011, 03:08 PM
#5
For whats it worth, years ago I had a LS6 in my car, pulled it out and went it a LQ9 iron block and re-used my cam and LS6 intake. My car had more hp but still ran the same et due to added weight.
02-21-2011, 03:28 PM
#6
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you also gotta think how light the car is already, if you have a 2500lb car that runs 13.0 and a 4000lb car that runs 13.0 taking 100lbs out of the lighter car will net you a much better gain...also does anyone know how much MPH you get for every 100lbs....is it 1?
02-23-2011, 01:32 AM
#7
do you remember how much HP you picked up going from the 5.7 to the iron block? Also did you use the same heads?
That only applies to slower cars really. I dont know where the et or weight rules change but I know on my car 10hp does even effect my et. My car was tuned at the track then put on a mustang dyno and picked up 25-30rwhp and my et's are still the exact same. The faster you go the more hp it will take to drop your et. Same thing with weight, drop a 100lbs out a 12 sec car vs a 8 sec car and you wont get the same drop in et.
For whats it worth, years ago I had a LS6 in my car, pulled it out and went it a LQ9 iron block and re-used my cam and LS6 intake. My car had more hp but still ran the same et due to added weight.
For whats it worth, years ago I had a LS6 in my car, pulled it out and went it a LQ9 iron block and re-used my cam and LS6 intake. My car had more hp but still ran the same et due to added weight.
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02-23-2011, 07:45 AM
#10
That only applies to slower cars really. I dont know where the et or weight rules change but I know on my car 10hp does even effect my et. My car was tuned at the track then put on a mustang dyno and picked up 25-30rwhp and my et's are still the exact same. The faster you go the more hp it will take to drop your et. Same thing with weight, drop a 100lbs out a 12 sec car vs a 8 sec car and you wont get the same drop in et.
For whats it worth, years ago I had a LS6 in my car, pulled it out and went it a LQ9 iron block and re-used my cam and LS6 intake. My car had more hp but still ran the same et due to added weight.
For whats it worth, years ago I had a LS6 in my car, pulled it out and went it a LQ9 iron block and re-used my cam and LS6 intake. My car had more hp but still ran the same et due to added weight.
Though I agree that on a 9 second car your not going to get 1 tenth from 10 hp but on stock cars you can still generally follow the rule. The rule is not static nor linear, its going to change as the ET/MPH changes. IMO once you hit low 12's the power/weight req start to change.
Maybe its more like a rule of percentages vs actual figures. For example, from quite a few different Dyno operators the general rule of thumb is the car needs to increase power by approx 8% for anyone to actually "feel a difference" so on a 320 rwhp fbody you need to see at leas 26 rwhp and for most mods that will not happen on one shot.
At least thats how I see it.
IMO the lighter the car is, its less weight to travel 1320 feet, and the more steam you have, given the car can find traction will help it get there faster.
That is a solid rule.
