Dude, Phoenix`97, you're looking at this all wrong. Stop looking at LSA, lift, duration, etc. Those are all cam specs of a RESULT of cam timing and lobe characteristics. You want to look at AIRFLOW in and out of the engine. You want to optimize the airflow in/out of the engine in the RPM band you want your torque to peak. Generally speaking, peak VE and peak TQ will correlated closely. So look at VE.

Take the TBI swirl port heads as an example. The off idle torque is amazing. Tiny intake ports, small cam, very little (none?) overlap. Those are the RESULTS of maximizing airflow in and out of the engine for low RPM torque.

For what you want, bore/stroke the engine, put larger valves on the heads and leave the ports on the head as small as possible. The smallest headers you can find will work best for you (1-5/8" can be found, but 1-1/2" would be better if you can find them).

For the intake manifold, the longer runners do help with low RPM air intake charge velocity but it doesn't seem to make a huge difference. The stock LT1 produced more than 90% of it's peak torque from 1400 RPM to 5000 RPM ( isn't this exactly what you are looking for). The LT1 also peaks torque at 1800 RPM completely stock. That's enough for me to not mess with the intake at all. Leave it as is, any modifications to this area will likely not have a notable impact.

If you look at your head flow numbers on a stock LT1 aluminum casting, there is NO benefit to going over ~.500" lift. So, if you want to increase how much air get's into the engine, then you need to increase how long the valve is open at the equivalent of .500" with the stock valves. Increasing the valve size will do exactly that. It will flow more at any given lift point. The cam you'd want will be similar to stock, but with more aggressive ramps (open and close faster, not necessarily more). You want to increase AVERAGE lift, not total lift (total lift increases average lift, but a better cam lobe profile can increase average lift more than higher ratio rockers or higher peak lift will). You want your average lift as close to peak lift flow numbers as possible.

Increasing bore and stroke will increase air intake charge velocity (along with increase actual torque production mechanically). This will allow you to run a bit larger cam (duration) than stock that gives a little over lap. Add in small diameter headers and now you can possibly even add low RPM scavenging to your project. This would further increase your air in/out and VE, and torque.

The biggest thing you'd have to figure out is WHEN you want the valves to open and close. The cam specs (duration, overlap, LSA, etc.) will be a result of the valve timing events you need to maximize the torque you want at the RPM you want in the engine you build.

I'd start with a good valve job (with larger valves), and bore/stroke it.

The thing is, with all of that. You can increase low end torque (quite a bit) and not loose much high RPM power if you did a small port job on those heads. JMHO.

 

@hrcslam

Thank you for your comment. Okay, I will start researching larger valves and what dynamic this will introduce for this project. Unfortunately, I have no interest in boring/stroking the engine even though this would give me a healthy bump in low end torque without messing with the gear ratio and using the stock cam. I am very **** about preserving my city mileage which is why I am trying to research alternative avenues with non-stellar performance improvements, to give me what I seek without messing with the rear gear ratio. Furthermore, this car will be a daily year-round driven car, so it will see snowy weather which is why using a stroked LT1 is not practical for such driving conditions and why I wish to keep her a 5.7L engine. My options are limited given my parameters to work with...

Also, I am dead-set on using the B-body cast iron cylinder heads that flow 200 cfm with the long runner intake I am going to use. Yes, the TPI won't help but mildly hurt my off-idle torque up to 2500 since the short runner stock LT1 flows better but the torque production from the TPI intake will more than make up for this sacrifice from 2500 RPM on up to 4500 RPM. This is why my research is focused on how to tailor the camshaft, basically modeling performance off of the stock LT1 cam to work with 1.7 rocker rollers to give me a combined .51 lift using the cam lift at .3. In theory, even with a wide LSA of 120 with extremely minimal overlap so that I don't have to worry about exhaust scavenging for a tighter LSA grind, I should see a boost in off-idle torque despite the trade-off from using the TPI intake. However, I won't stop here, I do want compression bumped up to 11 using the cast iron heads which will require shaving them, but I need to have access to Iso-Butanol fuel and be able to purchase it regularly, in order for this plan to work. From this, I stand to gain some more off-idle torque.

All I care about is gaining the torque level I currently achieve at 2000 RPM and shift that down to 1000 RPM or at least 1500 RPM with this given set-up. It is not impressive at all but it will give me what I seek and help to preserve my city fuel economy if not help to improve it with more low RPM cruising. This is the nature of my madness in this pursuit and research...

 

Doing some searching on increasing the valve size on cylinder heads with respect to a stock type street car, the best tale of caution I found was from this site.

Do larger valves increase performance?

Yes, this information is based on Chevy 305 heads for the comparison and not the LT1 350 heads for my application but it reveals how this modification is not the best idea for what I want to have done to my engine and how I want it to perform. I don't care about high RPM flow rates when I am focused on low and mid-range flow in order to increase power/torque as much as possible from where they are now in my stock configuration.

I don't want to port my stock heads and by going with cast iron LT1 heads I get better flow anyways without the port work. So, I do apologize for driving some of you members nuts with what I am trying to do with my car, but again, she is not going to be built like a race car, far from it.

 

Torque on the LT1 at 2000 RPM is about 325 ft/lbs, at 1500 RPM your looking at about 295 ft/lbs. You're already there.

Engine displacement has little to do with Fuel economy. Also, it doesn't matter if the engine is a 2.0 or a 6.2, if you're putting down 400 ft/lbs of torque in the snow you're going to have the same traction issues. Where the 2.0 helps is that is won't put that torque down at or near idle (what you're trying to accomplish).

What you are trying to achieve is opposite ends of the same spectrum, simultaneously. Traction in the snow and 400 ft/lbs of torque don't go well together in a 3400 lb RWD car.

Valve size vs air flow has it's limits, true. But comparing the 305 head (with smaller bores) to the LT1 isn't the same thing. 2.00/1.56 valves work very well on the LT1 and it's 4.00" bore. But it isn't just putting larger valves on. You need to accompany the larger valves with a valve job. Cutting the head to the valve, working the bowls for the valve and de-shrouding the chamber for those valves. You'd be surprised what you gain in air flow with that. Read This (Ford 351 heads in this example, but with 170cc intake runners (same size as the LT1) and on a 4.000" Bore (Same as the LT1)). What you are trying to accomplish is less restriction at the valve at every lift point without making the port larger in diameter, this increases velocity compounding the effect.


Or, if you just want the "feel" of the TPI. Stick a 58mm TB on it and re-tune the Engine/Trans for that and call it done... Or get a TPI engine.

 

I am trying to take into account that with the TPI intake any small gains in torque will be lost off-idle on up to 2500 RPM where the long runners will kick in to boost torque back up and well beyond the stock LT1 short runner intake. This is why I want the TPI intake, for this gain in the RPM band from 2500 to 4500 RPM. However, I have to simultaneously figure out how to achieve my goal of bumping up the torque number off-idle and/or at 1500 RPM to match what I am currently receiving at 2000 RPM to satisfy my cruising requirement. I am expecting to meet or possibly supercede this amount by a little bit.

With regards to putting down 325 ft/lbs or a bit more of torque in the snow, it is a matter of clutch control and a matter of having the correct tires for the driving conditions. I have no problems driving my car at 2000 or 2500 RPM in the snow so long as there is traction, otherwise I am just spinning the rear tires. It also helps to have some weight added to the hatch which I have a cement block for that. I am just hoping I can achieve 325 ft/lbs or a little more at idle or at 1500 RPM with the TPI intake! Once I achieve this, imagine the torque once I tap into the TPI torque band at 2500 - 4500 RPM! Yeah, it's a pittance and unimpressive to the rest of the community but for street performance and what I have been used to after driving this car stock for 10-years, it will finally be a fun ride, reminiscent of the TPI F-body cars.

I will look over this article you provided and reevaluate my stance on whether to use larger valves with the necessary modifications to make them work. Don't forget, I am going to use the cast-iron LT1 heads! For winter driving, the cast-iron will be better suited for the temperatures and for the sake of better thermal efficiency for combustion, the cast-iron is the way to go for my application.

 

Man readin that gave Me a Headache!!!
Pretty Sure the answer in in the posts But You Wont Listen LoL
The Key to More TQ in a 350 sbc in any Variant in My Opinion is 6in Rods and a Single Pattern Cam!!! Call Comp and have them put an LT1 nose on the Magnum roller thats 206 @.05 .500 lift and put it on a 110 and run 1.6 rockers for .530 lift!!! A Single / Straight pattern Cam Makes More TQ Period!!! Then have it Tuned!!! Thats the exact cam Im gonna run in a 383 build because I want MAX TQ

 

With the headache I am sure some other subtleties were missed. I am not going for MAX TQ like you are, just as much of an improvement as I can achieve with a .3 lift cam and heads using 1.7 RRs to give me a total .51 lift, slightly reduced duration from my stock cam, and with either a lobe separation at 117 stock or wider at 120. I fully intend to make use of a modified stock TPI that can bolt on to my LT1 heads, this will give me a nice playful torque curve from 2500 RPM to 4500 RPM. It is nothing amazing but for a daily driver LT1 it should be more fun than what I experience now, severe lag. However, we can't rule out the car is old and needs refreshing throughout.

I am not changing my stock rear gear ratio since this is optimal for the daily driving conditions I endure. So, in my stubbornness, the set-up I will have built for the money will be less than impressive but that is not my goal. I want a dedicated street car that will be quite the traffic light hopper that the L98 TPI was back in it's day. If I can manage using a higher octane fuel on the regular, I can get away with shaved cast-iron LT1 heads with 11 compression, so performance wise I stand to achieve an improvement, although it won't be massive but that is not the point for what I want to achieve!

On a last note I found an article that stressed that if you are to use a TPI intake with a high lift set-up, you want a wider lobe cam and not something tighter. The guys with stock L98s said the 117 lobe stock cam made the engines more sporty and come alive compared to the previous 114.5 lobe cams. I have to go with what I have learned works for this intake.

 

I cannot believe a thread like this about making an LT1 slower than stock has gone on for 2 pages in this forum.

If you want a diesel go get one. Or just go buy a TPI Trans Am or IROC, they're plenty affordable these days.

 

I thought this thread was dead...

Well, do I really have to apologize that I am committed to this build? I don't enjoy high revving my car to tap into it's torque after 5000 RPM! I am not one for straight-line racing, although I have come to realize that auto cross may be up my ally given my joy for tight turns and even the thrills I take in recovering from fishtailing in my car during the height of a snow storm. Pretty much, during my street drive, from 2000 RPM to 5000 RPM, it feels like nothing but a huge dead spot! The torque curve for my car in this RPM range is flat as well. I have a clear as day expectation for what I am seeking out of this car given my many months of taking in the advice of members on this site. I want torque that I can feel in the RPM range where I want to feel it for my daily drive and only the TPI INTAKE can deliver on this desire of mine. The TPI intake is the first step to shift the torque curve of a second-gen LT1 to something more enjoyable for a daily driver, not a drag strip car! The next step is putting together the right combination of engine parts and exhaust to complete this overhaul and give me what I am seeking, a fun as hell daily driver that kicks *** at every traffic light up to the 1/4 mile where the intake limits it's performance thereafter. However, in daily driving, I am lucky to have a 1/4 mile to accelerate up to 45mph or 50mph! Another added benefit to this set-up is that it shouldn't kill my factory rated fuel economy, it's not like I am using the batch fire injection system on my engine!

Now, there is plenty of opinions against the merits of using cast iron heads with this set-up. However, for a daily driver that drives in the winter, it seems like using cast iron heads is the better choice despite the penalty of added weight. Then, I am still trying to figure out if using a custom grind cam in tandem with 1.7 rocker rollers with this set-up will finish off what I am looking for. A custom cam with the same lift as my stock cam, with slightly less duration to take into account the torque shift up the RPM band from the 1.7 RRs, and having the same 117 LSA or trying out a more emissions friendly 120 LSA. Many L98 guys have mentioned how the 1988-1989 cam is very close to the specs of the second-gen LT1 and yet it was the more "sporty" of the cams by comparison to the 114.5 LSA cams that came before. So, my thinking is that a cam with a more flat torque curve will actually work best to compliment the torque peak of the TPI intake. I need simulated data to support this hypothesis.

Then, I am seriously considering an ignition system swap over to the torque head 24XX. Tuning to have my ignition system more oriented around low RPM torque will help to finish off this build and make up for the drop in torque that comes from the TPI intake when compared to my stock LT1 intake from off-idle to 2000 RPM.

I now have a complete stock TPI assembly off of a '91 Camaro and I had to get the TPI base from a '91 Vette to be able to use my EGR tube. Later on, likely when I am half-way through getting my Bachelor's degree, I am going to see how much it will cost to have a machine shop modify the TPI base to get it to bolt directly on to my second-gen LT1 heads. The coolant passages won't be used so they don't need to be blocked off. Then, I need to see if they can get an LT1 fuel rail to bolt on to the TPI base so that I don't have to get creative with my fuel line for this swap.

After all of my research which is still ongoing, I am convinced that this is the set-up I need to focus on to give me what I seek.

 

I am sure its been mentioned before, but quite literally bolting on a P1sc with a 24x setup will do what you are wanting and not ruin the car/your dreams.

 

I have thought about supercharging my LT1. However, some issues come to mind.

1. Adding a supercharger introduces more parasitic drain to the pulley system. I want to minimize parasitic drain which has also got me researching a pure electric power steering conversion to eliminate my hydraulic power steering system.
2. Having the supercharger constantly running means there is more airflow. The problem comes with winter driving. The added airflow is definitely going to kill city driving and sip more fuel when idling. Furthermore, I can't have too much torque production down low when spinning the tires is too easy on snow covered streets with ice underneath. This makes a turbo more ideal for both fuel economy and maintaining stock toque at very low RPM.

Believe me, I have thought this through very carefully and basing everything on the need for a pure street car that will be winter driven and that must try to preserve factory EPA rated fuel economy for the city, and a car that may see auto cross events in the future. Time and time again I go back to the TPI intake and realize that is what I want for this build! I don't understand how this intake will "ruin" my LT1 so long as the car has the correct tune for the intake which is why having an LS1 computer and direct ignition is probably the best way to ensure I can get the most out of this set-up.

Now, if I want MORE POWER, I can always have them throw on a rear mounted twin turbo set-up with a snorkel for the intake built into the fenders. I will truly have big block torque at that point and the drop off after 5000 RPM won't be an issue with how high the torque will be from the forced induction of the twin turbos. I merely see the benefits of using the TPI Intake or as someone on a hot rod article coined a new name for it (Torque Producing Injection).

Now, if the First TPI intake had the provisions for my stock emissions equipment, I would likely be asking them for a custom intake that bolts directly to my LT1 heads. Since they don't, and since the stock TPI is tuned at the right RPM range I want for my torque production, I am better off swapping parts off of my LT1 intake on to the '91 TPI intake system I now have.

 

I have personally run the TPI intake and comparing it to a dual plane performer RPM intake with a 454 TBI unit on it the TPI only marginally beat out the TBI in the 2,700-4,200 rpm range and lost considerable power below and above that RPM range.

The 90-92 TPI engines made the most power and were the most responsive. The LT4 cam murders the L98 cam alive and it was on a 115 LSA.

You are also shooting yourself in the foot with the cast iron head idea. For one thing they are HEAVY. Put an extra 50 lbs in your car and drive around town for a week. You will see a slight decrease in fuel mileage. Then add to the fact they have pressed in studs and the top of the stud bosses are not machined for guide plates. Finally the aluminum heads reject more heat into the coolant naking the engine warm up more quickly which gets it ibto closed loop faster which means less fuel consumption. Putting cast iron heads on is the equivalent of dropping one of these on your foot for stupidity.

I would call Lloyd Elliot up and tell him what you want to do. Have your aluminum heads ported and keep the stock valve size. Go with his spring setup to allow for 0.580" lift. Let Lloyd port your factory intake to match. Then let him provide you with a cam along the lines of his "Sleeper grind". If you can run them get a set of long tubes or at the minimum let Brzezenski port your factory manifolds. I bet if need the manifolds for smog compliance and you contacted Brzezenski they could port your factory manifolds without the extra modifications needed to put them on a non LT1 race car. Which visual inspection would likely also prevent your TPI intake idea. Then TUNE the thing. You will gain power everywhere without losing fuel mileage or swapping to a TPI or whatever other blunder you want to create.
​
LLoyd's site
http://elliottsportworks.com

Brzezenski
https://www.castheads.com/manifolds-carb/exhaust-manifolds/lt1-exhaust-manifolds/

 

Hey partner, i usually just lurk in the LT1 section since i dont have a whole lot of experience into them at this point, just opinions gleaned from here. And no, i really haven't read this whole "IT" novel of a thread, but i have seen you say this a couple of times. so i have to ask.

...how?
i mean, are you talking relatively to other cars youve driven? or you just dont feel your back pressing into the seat during this range?

if its the latter, im just going to say the basic bitch knowledge of "you need gears". My old hunk-o-**** has nothing new in regards to the engine, just exhaust, intake, and 4.10's. ive never driven an f-body with stock gearing but the only reason that i believe this car isnt boring and has not become boring to me is because of its 4.10's. through that range you mention i may not have speed of H/C or LS1 cars, but what speed it does have its putting all that it has down to the earth from 2k-5k enough to still be impressive (to me) for a 22 year old car. that and the 285's in the back probably help with that too.

and, if i can humbly say, man part of being a knucklebuster is just pulling the trigger on something and say "**** it, plug it in, see what happens". I know you want to be over prepared, dont want to waste money, no body does. but, "plans rarely survive enemy contact".

 

I am fully aware that from 1000 RPM to 2000 RPM, the TPI intake does not produce the torque that my stock LT1 intake produces. This is the trade off between the long runners of the TPI and the short runners of the LT1 intake. This is where I figured I could offset this loss by having a custom grind cam which mimics my stock cam and works with 1.7 rocker rollers to yield high lift at no more than .51 and with slightly less duration so as to keep the torque behavior on par with the stock LT1 cam. I am sure tuning the ignition for more torque down low will also help offset this problem which is why the torque head ignition will be beneficial for this build.

Alright, with regards to the LT4 cam, it probably does outperform the 1985-1987 L98 cams with 114.5 LSA. However, the 1988-1989 L98 cams were closer in spec to the stock LT1 cam which has more lift than the LT4 cam using 1.5 RRs. From what L98 owners have told me, the LT1 spec L98 cam was the "sportier" of those cams and I even found evidence on TPI build suggestions with higher lift cams that you want wider LSA! For my custom cam grind it makes sense to see if 120 LSA would be even better than 117 LSA and granted I am seriously considering using the stock exhaust manifolds, made by Brzezenski, due to the all the problems with my Hooker shorties and my gut feeling that I did lose some low end off-idle torque to favor higher RPM performance. Again, what I want to do with my LT1 is in total contrast to what you all do to your cars!

I am not driving a four-cylinder car here! I am basically planning to have my LT1 turned into more of a torque engine! With the added torque the extra 50 lbs won't make that much of a difference! Furthermore, with me cruising around town in lower gear owed to the extra torque the engine is now producing, I should, in theory, use less fuel than I otherwise would with the current set-up.

Yes, I am aware of the press-in studs of the cast-iron B-body LT1 cylinder heads. I will need to pay the dough to get those drilled out and modified accordingly with the correct geometry for the 1.7 RRs. It is well worth it in my mind!

I could not disagree with you more! Larry Carley has another perspective you need to consider!
Don’t Gamble When Choosing Cylinder Heads

Quoting the article,
"Aluminum conducts heat faster than cast iron. This helps cool the engine and allows a higher compression ratio with less risk of preignition or detonation — but it also sucks heat out of the combustion chamber and actually reduces combustion efficiency somewhat. At high RPM, there’s less time per combustion event for heat to escape through the cylinder head so the loss in thermal efficiency is not as great.

On a street engine, cast iron heads help an engine reach operating temperature more quickly after a cold start (good for emissions and cold drivability), while retaining more heat for improved fuel economy and thermal efficiency. Most cast iron heads are also less expensive than aluminum heads because the metal is less expensive."

So, who is telling the truth? Yes, aluminum bleeds out heat faster which gets lost to the engine bay! So when you really think about it, it only helps to keep an engine cooler and longer which is great for racing applications but poor for a daily driver that sees below zero or even minus 30 degree Fahrenheit temperatures! This car is a daily driver year round, and I am willing to wager that cast-iron heads will also help to improve my fuel economy and emissions, then add on an LS7 inspired emissions cam with an LSA of 120! I literally am dreaming up a brand new second-gen LT1 that should have been offered by GM as an option.

I e-mailed Brzezenski last night about this project and information I needed to know about their cast iron exhaust manifolds, whether they need ceramic coating since they don't have the factory aluminum heat shields, and whether they could benefit from an extrude hone or not and whether that is even worth my while since I read SLP used to do it for the LT1 Firebirds and Camaros.

Lastly, I asked them whether or not they could drill the holes needed for the TPI base on cast-iron LT1 cylinder heads that they modified to make use of 1.7 RRs. The guys that modify the LT1 intake to use on L98 heads have to drill the intake base to get it to fit, along with other things like the distributor hole. However, my problem with the TPI base is that I don't have the drill holes where they need to be and it appears that the very simple solution is to have the extra holes drilled into the cylinder head! I could be wrong but that is what it looks like from pictures. If that is the case then the swap is easier than it seems!
​

 

Having had aluminum heads and cast iron heads on the same engine, the aluminum heads heat the coolant faster because they reject heat into the cooling system more quickly. The PCM reads the coolant temperature and adjust the fuel delivery and timing advance during warmup. With my cast iron head L31 engine I could drive for several miles and still not have the temp gauge move! My M56 with its aluminum block and head warmed up in mere blocks. Keep in mind this extra heat dissipation also allows the aluminum head to run a more aggressive timing advance map for every given load and RPM point. You can also use this improved heat rejection to allow for increased compression ratio. Aluminum heads typically allow for 1/2 to 1 full point more compression than a cast iron head running the same timing advance and same octane. Finally if you are that worried about the heat loss, run a higher temperature (205*F)thermostat and turn the fans on at a higher temperature. I will personally never run a cast iron head engine again if I can keep from it.

You also need to get the whole LSA thing out of your mind and learn it has to do with valve timing events. Tighter LSA traps more cylinder pressure by advancing the intake valve events. What hurts low-end is overlap.

 

You said you have experience with aluminum heads and cast iron heads on the same engine? The LT1 and L31...(Vortec?) are not the same engine. The best test would be experiences of those who have driven and own an F-body and either B-body or D-body. Okay, let me give your comment a chance here.

You say your cast-iron heads kept the vehicle cool and for longer than with aluminum heads on the other vehicle. It is really interesting because in very cold weather, 32 Fahrenheit and below, I need to drive well over a mile before my temp gauge moves, and this is with around 5 minutes of warm-up time before I leave the house! I have full coolant, full heat when the engine gets up to temperature. My experience tells me that the heat retaining cast iron would be far better in heating up the engine coolant faster than at the rate aluminum allows heat to dissipate which would, logically, reduce the amount of heat that the coolant receives! However, unless a B-body or D-body LT1 owner can tell me their story and refute my assertion, I really have a hard time believing that the aluminum heads warm up an engine faster. Moving on.

Yes, timing will be something to consider granted the cast-iron heads retain heat and are more prone to pre-ignition. Well, this is where having the reliable reverse-flow coolant system working helps as well as to use a higher octane fuel and I am sure many of you know which alcohol fuel I am pushing here! Yes, you can increase compression for an aluminum head but you can also increase compression for a cast-iron head as well and receive double the benefits with better thermal efficiency and more power than the aluminum head at the same compression ratio. However, you need higher octane fuel to safely do this and I know an alcohol fuel that is perfect for this job, assuming I can purchase it regularly and without disruption.

Yes, I am very stubborn! I already have a stripped header bolt hole on my driver side head which I salvaged with a bigger non-header bolt! I will gladly take the extra durability of the cast iron! My car is only a daily driver and may have a future being a part-time auto cross car.

 

It was a L31 engine that I swapped from cast iron heads to aluminum heads. If there was a warmup issue from them that vehicle would have more of an issue than a F-car or B/D car for that matter. It has a massive 4 core radiator and a large mechanical driven engine fan.

Aluminum heads dissipate heat from the combustion chamber and valves into the coolant faster.

 

They simultaneously disperse that heat to the engine compartment. There is a reason why the combustion chamber in aluminum heads is cooler than cast iron! Cast iron combustion chambers have an issue with being too hot! All metals transfer heat, in this case the coolant is going to start warming up. The question, however, how fast does coolant reach the cylinder head temperature in an aluminum cylinder head that is also bleeding off that heat to the engine bay versus the cast iron cylinder head which is retaining most of that heat making the cylinder head hotter which in turn is giving more heat to the coolant.

Hot Topic: Iron vs. Aluminum

Quoting the article, “Aluminum heads dissipate heat quicker than cast iron,” echoed Torrance, California-based Edelbrock’s Smitty Smith. “This can be an advantage in elimination-style drag racing, keeping the head temperature consistent round after round.”

From the thread.

 

Damn this is one long winded thread...but entertaining to read. If you're looking for big block torque you need to stroke it and cam it. Find a cam that makes the power in the rpm range you want, 2000 to 5000 and put it together. You have way over thought your build. You are never going to achieve Big Block torque without doing a bunch of mods...its not rocket science. It will be interesting to what gains you get from what you are planning ( if you do it ).....probably going to kick yourself in the *** after you realize you've wasted a lot of time and money for very little

 

Tell me about it.

I AM NOT LOOKING FOR BIG BLOCK TORQUE! My comments are, once again, being taken out of context. When I made this comment I was referring to the 1988 Callaway twin turbo C4. This car certainly made big block torque within the range that the TPI intake makes it's torque, and with twin turbos. I was merely stating that I could always go about this set-up on my Trans Am if I want more power down the road but I have no interest to do so, and it would mean scrapping my Ram Air hood and air cleaner system if I am using forced induction from a rear mounted twin turbo set-up. Furthermore, having a wider lobe camshaft will be ideal if I do decide to have twin turbos thrown on my car at some distant future date.

Everyone makes the assumption that I won't be happy with this build I am hatching up in my mind and planning/preparing and researching for. I personally am not out to build a high horsepower race car and I certainly don't drive my car in a manner where I would use the engine's power in those higher RPM bands. I am happy with my current rear axle gearing, I am not happy with the lack of pull that I expect out of my V8. It is clearly evident that I want a torquier engine than the LT1 is in stock form. I don't want to stroke the engine, I want to keep it a 350, so pretty much that further narrows down my options to the TPI intake, the closest and nearly interchangeable intake I can use to bump up my LT1's torque in the RPM band I use for "fun" and hard acceleration. More torque will give me just that!

I said a while ago in either another forum and some other thread that I should first have the factory TPI installed on my engine and PCM tuned accordingly, and see how I like it. Depending upon what happens later on, I will see if I can go about this. The camshaft idea and 1.7 RRs is a means to further increase power from a rather stockish performing cam. I figured this would help to bump up off idle torque by just a bit more to keep it on par with the stock LT1 torque from 1000 to 2000 RPM where I spend my time cruising around town. Beyond that and up to 5000 RPM, the TPI intake should produce a bit more torque from my stock cam with 1.5 rockers. It won't be that impressive by the standards of others but certainly enough for me to notice and that is all that matters! The cast iron cylinder heads, from my research, will also help in torque production due to the thermal efficiency of it's combustion chamber. Then the last thing is putting cast-iron exhaust manifolds back on my engine now that I realize I was duped by marketing for the shorty headers. Oh well, better to learn it now than later.