Can you modify L31 Vortec heads to work on a second-gen LT1?
05-11-2018, 02:51 PM
#182
Nope. I am in disbelief that philosophy is being fought over. I want low end and mid-range torque out of my LT1 and that is it. I don't care about gearing to amplify power output. I never said L31 Vortec Heads were better flowing than other market heads out there. For my application at low lift and lower RPM, the Vortec heads would be perfect and not to mention my LT1 heads don't have tall ports, a borrowed design feature from the LT4 heads that made it's way into the Vortec heads.
I can't get an honest answer and even not commenting on this thread is better than the b.s. I am reading with members trying to prove their philosophies with regards to engine building. Just give me a straight answer and don't get offended when I have to question it. Damn!
I can't get an honest answer and even not commenting on this thread is better than the b.s. I am reading with members trying to prove their philosophies with regards to engine building. Just give me a straight answer and don't get offended when I have to question it. Damn!
05-11-2018, 03:20 PM
#184
Team Owner
Pro Mechanic
05-11-2018, 03:47 PM
#185
Race Director
Nope. I am in disbelief that philosophy is being fought over. I want low end and mid-range torque out of my LT1 and that is it. I don't care about gearing to amplify power output. I never said L31 Vortec Heads were better flowing than other market heads out there. For my application at low lift and lower RPM, the Vortec heads would be perfect and not to mention my LT1 heads don't have tall ports, a borrowed design feature from the LT4 heads that made it's way into the Vortec heads.
I can't get an honest answer and even not commenting on this thread is better than the b.s. I am reading with members trying to prove their philosophies with regards to engine building. Just give me a straight answer and don't get offended when I have to question it. Damn!
I can't get an honest answer and even not commenting on this thread is better than the b.s. I am reading with members trying to prove their philosophies with regards to engine building. Just give me a straight answer and don't get offended when I have to question it. Damn!
Have you ever done a cost analysis to estimate cost, guesstimated fuel savings, or whatever to tell yourself if a given project is even worth it? I doubt it. If so, share THAT thinking (I say with great reservation). Because I think it will confirm how poorly thought through these ideas are. Don't "cop out" either and talk about all the pollution you'll be saving...and how the cost is worth it. If you do, you might as well include THAT analysis...then tie it back to production costs, carbon "waste" from the food to earn the money, and any other offset issues that apply. After all, for someone with THAT level of ideal, you have to consider everything.
For your goals, buying a longtube TPI intake had better merit -- how ever small. The way you IGNORED the opportunity to actually buy one (ebay link) proves you are a troll. You don't actually want to do something...or even save for...and wait on something. You just want to spout BS and cry when people realize there's more interesting and BENEFICIAL conversations to be had -- than with you.
Spouting BS and crying may be understandable -- while having a president who promotes that approach each and every day. Do you think it's working well for him? In response to Trump's overwhelming NONSENSE, do people "stand-up" and write congress OR OBJECT? Or do reportedly "sentient people" actually INVENT other problems to prove how Trump is so great? You know...like discrediting our entire law/judicial system? You know...to DEFLECT from the fact he is more corrupt than those he "held up" before taking office!!!! Between this forum and stupid-azz politicians, which of us deals with DUMB topics better? At least you can learn something here.
Your idea was a dream...an "invention"...not a solution. You are trying to peddle fake news with this L31 idea. LOL
This has ALSO been a closer look.
Now...let's all get back to reality......Stroker or gears....stroker or gears....stroker or gears....
Last edited by GREGGPENN; 05-11-2018 at 04:15 PM. Reason: Wanted to qualify that a TPI wasn't stellar either -- though marginally better
05-11-2018, 03:50 PM
#186
Le Mans Master
Yes, again a CVT is illustrative: it holds power constant and the wheel torque (or tractive force) varies inversely to the velocity of the car (or rpm of the drive wheels.
Power IS a quantity that can be measured at one speed even if not accelerating at all.
Instead, we go with power=force*speed (which is essentially the formula for horsepower), like you said. So even without acceleration, power is applied, unless we're in space (nearly perfect vacuum) where no force (thrust) is required to maintain velocity.
Power is proportional to torque times RPM (with a conversion factor, 1/5252). So you CAN determine torque out from torque in.
Absent the info about the gear ratios and tire radius, if you know a car is traveling 60mph and the engine is outputting 300lb/ft of peak torque at the crankshaft at that speed, you still have no idea what the tractive force is. The engine might have be putting that torque peak out at 3000rpm (e.g., a diesel) or 6000rpm (e.g., a sporty gasoline engine), or any other rpm. We don't know. The 3000rpm engine will accelerate the car from 60mph at half the rate as the 6000rpm engine.
Lower gears increase the torque out by a factor inverse to that of the RPM [at the axle], so the power in, power out rule isn’t violated.
My car has an incredibly flat torque curve from about 2000 RPM to nearly 5500 before it starts falling off. Amazing. Power starts small and ramps up nearly linearly. (Peak of 307 lb-ft and 305 HP at wheels). Although, acceleration is great even at 2000 RPM, and is steady all the way up to 5500. Power peaks at about 5500 and is quite flat until 6200 where testing stops/red line/rev limit. Acceleration starts falling off above 5500 as well.
So here are two truisms that coexist:
For any given road speed, a car always accelerates hardest at peak power rpm, but
Within one single gear ratio, a car always accelerates hardest at the engine's peak torque. But note that the peak-torque road speed is lower than the peak-power speed.
Also, acceleration would be lousy starting in 4th gear, right? But in 1st gear the torque is multiplied. Also, switching out the differential gears to a 4.11 will give you neck snapping acceleration too. Because it multiplies the torque output.
I’m not sure, but aren’t you confusing speed for acceleration? Acceleration is the change in speed per unit time. If speed is measured in m/s, then acceleration is m/s/s, or m/s^2. Tell me where I’m wrong.
05-11-2018, 04:24 PM
#187
I gave you ANOTHER honest answer -- which you ONCE AGAIN passed off. Those heads are a waste of time FOR YOUR GOALS and wouldn't provide enough (if any) difference in low/mid performance to warrant the time, effort, cost, etc... But, then again, this has been the mantra of this forum for your pie-in-the-sky ideas even if "original" or whatever.
Have you ever done a cost analysis to estimate cost, guesstimated fuel savings, or whatever to tell yourself if a given project is even worth it? I doubt it. If so, share THAT thinking (I say with great reservation). Because I think it will confirm how poorly thought through these ideas are. Don't "cop out" either and talk about all the pollution you'll be saving...and how the cost is worth it. If you do, you might as well include THAT analysis...then tie it back to production costs, carbon "waste" from the food to earn the money, and any other offset issues that apply. After all, for someone with THAT level of ideal, you have to consider everything.
For your goals, buying a longtube TPI intake had better merit -- how ever small. The way you IGNORED the opportunity to actually buy one (ebay link) proves you are a troll. You don't actually want to do something...or even save for...and wait on something. You just want to spout BS and cry when people realize there's more interesting and BENEFICIAL conversations to be had -- than with you.
Apparently not!
What about the inbetween? Stock gear ratio and more torque below 5252 RPM?
05-11-2018, 05:08 PM
#188
Le Mans Master
Ok what you want and what you get aren't always the same thing. The Cast Iron LT1 head will work. To know for sure the vortec head will work you will need to cut a cast iron lt1 and vortec head in half to be sure the are no hidden obstructions in the casting. Chevrolet did not design vortec head for reverse cooling. On other sites this topic is maybe 10 posts used the "the iron lt1 is the same as the stock vortec" but not here. If you want to jump your torque sleeve, your engine down to 3.875 stroke it to 3.75 you will end up a 355 ci. You could go smaller on bore but limited to l99 head. The cast iron LT1 heads or set of ported l99 heads keeping the 1.84 valves. The idea is to have a high intake velocity and since a low operation range is desired it should work out. The vortec or b body cam in it. long tube 1.50 headers feeding is to single exhaust for maximum scavenging. Fab a intake with a custom intake with a tuning valve so it uses long runners up to 2k and short runner beyond it. Then the fun stuff tuning it to work. The reality is this project is cost prohibitive especially when you get to your alternative fuel hybrid drive.
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Phoenix'97 (05-11-2018)
05-11-2018, 05:29 PM
#189
Team Owner
Pro Mechanic
Ok what you want and what you get aren't always the same thing. The Cast Iron LT1 head will work. To know for sure the vortec head will work you will need to cut a cast iron lt1 and vortec head in half to be sure the are no hidden obstructions in the casting. Chevrolet did not design vortec head for reverse cooling. On other sites this topic is maybe 10 posts used the "the iron lt1 is the same as the stock vortec" but not here. If you want to jump your torque sleeve, your engine down to 3.875 stroke it to 3.75 you will end up a 355 ci. You could go smaller on bore but limited to l99 head. The cast iron LT1 heads or set of ported l99 heads keeping the 1.84 valves. The idea is to have a high intake velocity and since a low operation range is desired it should work out. The vortec or b body cam in it. long tube 1.50 headers feeding is to single exhaust for maximum scavenging. Fab a intake with a custom intake with a tuning valve so it uses long runners up to 2k and short runner beyond it. Then the fun stuff tuning it to work. The reality is this project is cost prohibitive especially when you get to your alternative fuel hybrid drive.
05-11-2018, 05:43 PM
#190
Ok what you want and what you get aren't always the same thing. The Cast Iron LT1 head will work. To know for sure the vortec head will work you will need to cut a cast iron lt1 and vortec head in half to be sure the are no hidden obstructions in the casting. Chevrolet did not design vortec head for reverse cooling. On other sites this topic is maybe 10 posts used the "the iron lt1 is the same as the stock vortec" but not here. If you want to jump your torque sleeve, your engine down to 3.875 stroke it to 3.75 you will end up a 355 ci. You could go smaller on bore but limited to l99 head. The cast iron LT1 heads or set of ported l99 heads keeping the 1.84 valves. The idea is to have a high intake velocity and since a low operation range is desired it should work out. The vortec or b body cam in it. long tube 1.50 headers feeding is to single exhaust for maximum scavenging. Fab a intake with a custom intake with a tuning valve so it uses long runners up to 2k and short runner beyond it. Then the fun stuff tuning it to work. The reality is this project is cost prohibitive especially when you get to your alternative fuel hybrid drive.
If this is not doable then I wonder if perhaps Scoggin Dickey might be able to make me a TPI base for the LT1. Which I would then mate to LT1 iron heads since I am now in love with the material. We shall see.
Last edited by Phoenix'97; 05-11-2018 at 05:45 PM.
05-11-2018, 07:38 PM
#192
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Phoenix, I once had a 94 Corvette with an LT1, and it was wonderfully fuel efficient - when driven conservatively. I could get 20 mpg city and 33 mpg hwy. My 96 LT4, with heads that flow better and greater output over the entire operating range, I can only get 18 city and 29 hwy. For the amount of performance and fuel economy, the LT1 is already a great engine (except for maybe that opti spark, which I actually never had any trouble with myself). Of coarse, it IS a bit of a trick to know how to drive to get those numbers. If it’s fun... you’re not doing it right! So... I’m a little confused as to why you would want to mess with an engine that is so good as it is. If it’s just for experimentation, curiosity, and/or learning... then I suppose I understand. But your hobby may well become quite expensive.
05-11-2018, 07:44 PM
#193
Phoenix, I once had a 94 Corvette with an LT1, and it was wonderfully fuel efficient - when driven conservatively. I could get 20 mpg city and 33 mpg hwy. My 96 LT4, with heads that flow better and greater output over the entire operating range, I can only get 18 city and 29 hwy. For the amount of performance and fuel economy, the LT1 is already a great engine (except for maybe that opti spark, which I actually never had any trouble with myself). Of coarse, it IS a bit of a trick to know how to drive to get those numbers. If it’s fun... you’re not doing it right! So... I’m a little confused as to why you would want to mess with an engine that is so good as it is. If it’s just for experimentation, curiosity, and/or learning... then I suppose I understand. But your hobby may well become quite expensive.
Maybe, because he is a smart troll. Smart enough to keep folks interested and smarter than most here on engine building, but enjoys getting off on "testing" the corvette forum guys.
Last edited by pologreen1; 05-11-2018 at 07:45 PM.
05-11-2018, 07:51 PM
#194
Racer
The negative I see here is that although iron has a higher thermal capacity for heat it is very slow to release it. Although some argue this provides for a more complete burn the benefit is lost to higher chance of pre-ignition, this requiring a lower compression ratio resulting in decreasing power output and economy. Although weigh plays a small difference in why everyone has transitioned to aluminum the ability for higher compression stability and better thermal transfer to the coolant are the big winners here. This is the same reason guys who built high strung LT and LS based truck motors have issues with warped heads and cracks, the difference is speed and amount of expansion in the different materials. Mind you this is only happening to high strung engines put under severe loads for prolonged times. Also from someone who spent days reshaping my LT1 heads, aluminum is my metal of choice because of how much easier it is to work with.
One last point I would suggest you look for flow numbers of the L98, LT1 and L31 heads to compare at the same levels of lift. Flow numbers correlate with available velocity at given lift. I suggest this to warn you that you may be suffocating the LT1 too early even for your goals. I get you don't care about top end flow and that is fine but I feel the concern is that the L31 heads or any vortec heads for that matter don't flow as well as an LT1 at any velocity or lift.
05-11-2018, 08:22 PM
#195
Le Mans Master
What benefit do you see in the iron heads? Having owned and driven both the L98 takes for ever to warm up compared to the LT, and likewise to cool off.
The negative I see here is that although iron has a higher thermal capacity for heat it is very slow to release it. Although some argue this provides for a more complete burn the benefit is lost to higher chance of pre-ignition, this requiring a lower compression ratio resulting in decreasing power output and economy. Although weigh plays a small difference in why everyone has transitioned to aluminum the ability for higher compression stability and better thermal transfer to the coolant are the big winners here. This is the same reason guys who built high strung LT and LS based truck motors have issues with warped heads and cracks, the difference is speed and amount of expansion in the different materials. Mind you this is only happening to high strung engines put under severe loads for prolonged times. Also from someone who spent days reshaping my LT1 heads, aluminum is my metal of choice because of how much easier it is to work with.
The negative I see here is that although iron has a higher thermal capacity for heat it is very slow to release it. Although some argue this provides for a more complete burn the benefit is lost to higher chance of pre-ignition, this requiring a lower compression ratio resulting in decreasing power output and economy. Although weigh plays a small difference in why everyone has transitioned to aluminum the ability for higher compression stability and better thermal transfer to the coolant are the big winners here. This is the same reason guys who built high strung LT and LS based truck motors have issues with warped heads and cracks, the difference is speed and amount of expansion in the different materials. Mind you this is only happening to high strung engines put under severe loads for prolonged times. Also from someone who spent days reshaping my LT1 heads, aluminum is my metal of choice because of how much easier it is to work with.
05-11-2018, 08:41 PM
#196
Phoenix, I once had a 94 Corvette with an LT1, and it was wonderfully fuel efficient - when driven conservatively. I could get 20 mpg city and 33 mpg hwy. My 96 LT4, with heads that flow better and greater output over the entire operating range, I can only get 18 city and 29 hwy. For the amount of performance and fuel economy, the LT1 is already a great engine (except for maybe that opti spark, which I actually never had any trouble with myself). Of coarse, it IS a bit of a trick to know how to drive to get those numbers. If it’s fun... you’re not doing it right! So... I’m a little confused as to why you would want to mess with an engine that is so good as it is. If it’s just for experimentation, curiosity, and/or learning... then I suppose I understand. But your hobby may well become quite expensive.
Okay, since you got such mileage from a stock camshaft, I can safely assume that the more torque oriented B-Body LT1 cam should not hurt my fuel economy. This is the one camshaft I have in mind along with the ZZ4 which I read will require PCM tuning to maintain the torque levels of a B-Body camshaft and capitalize on the gains. The car is still stock at this point. Next up the heads, lets say I swap the aluminum heads over to the B-Body heads. Okay, I gain 40-50 extra pounds but the camshaft should have no problems handling it. If 40-50 pounds is going to break the car in fuel mileage then what about driver weight? Need to shed those pounds off to make the balance.
I understand, I am gambling with the TPI intake but the RPM range of this intake is right where my daily driving experience is at. The torque curve peak is just what I am looking for. I don't want to swap out my factory rear gear ratio when extra torque is just as effective at accelerating my F-body as is swapping out rear axle gears. To make the TPI intake work, I need a base to fit the LT1 heads or to modify L31 Vortec heads which I really think are just the reverse of modding LT1 heads to work on the first gen SBCs.
No, this isn't about satisfying curiosity, it is about giving me what I seek, seat of pants feel without having to go to the extreme of using a stroker kit and then butchering my city mileage. I drive this car in winter so a stroker engine is going to consume more fuel and I can't have that!
Last edited by Phoenix'97; 05-11-2018 at 08:43 PM.
05-11-2018, 08:44 PM
#197
Le Mans Master
You need to scan his first two threads related to installing tpi intake on lt1 and modifying TPI intake to fit (f body). Both are quite lengthy.
05-11-2018, 08:50 PM
#198
05-11-2018, 08:54 PM
#199
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Do you have an automatic transmission? It’s way easier to get better gas mileage when you have full control with a manual. Also, 4.11 gears will hurt gas mileage terribly.
05-11-2018, 09:00 PM
#200
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To be fuel efficient, keep RPM as low as possible while driving in the highest gear possible. Without “lugging” the engine. Mine got best mileage in 6th gear going as slow as possible. I think somewhere between 1500 and 2000 RPM. Don’t really remember.
