i dont know if you guys are following my little project but i still havent made a decision on an intake. i know i will eventually go with the lt1, but i cant get ahold of one and spring is coming fast. my goal is a 383 with as close as possible to 400hp. id love 400rwhp but i dont think it will happen. the car now is a 305 tbi and i know i'll scrap that and build everything new. i was thinking that since i cant find an lt1 intake, why not go tpi for now until i can get one ready. will the tpi be able to push 400hp. and if you do convince me to wait and go with the tpi now, who can sell me all the tpi stuff i need

 

You can get 400rwhp out of a 383 lt1, my friend has a 94 lt1 that had over 500 before it died a day later.. heh.. I hope you have a wad of cash. TPI stuff is cheap on ebay, lti intakes however have gotten twice as expensive.

 

can i get a list of engine specs of your buddies 383?
but can the tpi cough out 400hp for an engine that size?

 

I don't know what he had in the engine, I just saw the nitrous run that blew it up. IMHO it would be very difficult to get 400rwhp with a long tube runner setup, but 400 at the crank would be easy.

 

Tyler,
E-mail me concerning a LT1 intake.

millican@sethirdgen.org

 

with proper tuning, large tube siamesed runners and a hellllll of alot of porting on the TPI you should have no problem making 400 hp, I am sticking with TPI on my 383. The cool thing is that you can sacrafice low end tourque with the TPI by openign it up to make high end horsepower. most people would be against it on a stock motor, but a 383 makes huge tourque numbers down low, so U R kinda making a small sacrafice for a decent gain. Put soem decent heads on too, right now I am runnign stock but ported L98 heads, but in the spring I am taking my L98 heads and opening them up big time with 2.02 valves and all the good stuff

 

If you're talking about the aluminum L98 heads, dont bother putting 2.02/1.60 valves in them. For one thing, they wont fit, and another, they dont increase the flow well enough to justify the cost. If you're talking iron L98 heads, I wouldnt bother either, as they dont flow well enough by themselves to justify the cost. Save up for some good aftermarket heads for that healthy 383 of yours.

To the original poster, you'll probably want a SuperRam, or MiniRam, or some siamesed runners to help your engine make some good power. Long tube runners make for a nice engine, but it makes so much torque its very difficult to launch.

 

You can definately achieve 400hp on TPI.... at like 300RPMS. Once your in your last gear over that your power is going to take a dive. But TPI can put out numbers for you with the right combos. Power adders help too (don't they always ) The LT1 moves your power band to higher RPMS, it doesn't "bolt on 50hp over TPI". Nothing puts it out down low quite like TPI (except the LS1 of course). Even the LT1 can't match it. But when it comes to more useable hp in higher RPMs the LT1 has it hands down.

Also I have some TPI stuff to sell if you want to go that route. Just Email me with what you need.

 

this sig is well over 400

 

I think that if you are looking for numbers that high you should go with the LT1 intake. Think about it like this...Lets say you can get 400hp from a tpi intake. Race someone who is also making 400hp but using a LT1 intake, you will get killed. As stated earlier, the LT1's power band is much more useable. Did you email John?

-peace

 

yeah, i defaintly want to go lt1, but being home on weekends only really slows things down. not to add that the us exchange will kill me. i also still need the tpi ecm and wire harness. this is starting to **** me off, i cant get nothing done..well..for a reasonable price...

 

I have a mas air system that I can let go but It may not be the best choice for a 383 I may also have a lti intake no fuel rails or injectors Ill know monday plus I have a bunch of extra stock tpi stuff laying around I need to get rid of. I do have one complete tpi set up Im trying to sell it has slp runners SDPC vortec base TPIS AFPR and 22lb injectors ecm is off 87 gta and it has a hypertec chip in it but you would probly still need a new chip for the 383.

 

Earl, it seems as if i might of found a new hero

 

You guys keep talking about the LT1 intake, but what about the LT4, will that fit? That one's supposed to flow even better. Also by putting on one of these intakes, does it effect head choice, or do you just use them with the normal head? Is the article about converting the LT1 intake still floating around here?

 

The lt4 intake is not a good choice for standered port chevy heads but works great with vortec or fast burn heads.With stock heads you would have to port way to much off the heads to even out flow so that their would not be a wall when the air enters the head.

 

Tyler-88 Let me know what stuff you may be interested in Ive had a few replies on the vortec SDPC and slp set up.

 

85Transamtpi,

You stated a 400 HP LT-1 will kill a 400 HP TPI.... I don't understand... why is that ? What is your reasoning ?

Todd

 

85Transamtpi,

You stated a 400 HP LT-1 will kill a 400 HP TPI.... I don't understand... Why is that ? What is your reasoning ?

Todd

 

I think he means that in a 1/4 mile run he will pull harder at the end of the 1/4 and keep going ware as the tpi would take the lt1 from the start but be at its max at the end of the 1/4 .so their is still a good chance that the cars would run the same as long as both are set up right. given that you may get a little more from the lt1 but if you are running a 700 r4 with a stock TC infront of it and the tpi has a 2400 or even a 3000 in front of it you plus you have to think of gear and tire size its gooing to be hard to say with set up will run better. I think the biggest advantage of the lt1 is the abilits to gett more out of it later when you decide to try for 500 HP their isnt a lot of LR tpi set ups running 10 in the 1/4 but their are a few lt1s out their and most of them didnt change the intake to get their.

 

I'm not sure where this logic is coming from.... in reality, assuming both set-ups are the same raceweight, same gear and stall, whatever that is, the TPI will beat the LT-1 everytime.

Its very simple, if 2 vehicles have the same amount of hp, the one that can get to its hp quicker will win the race. A 400 hp LT-1 would need a hair more gear and stall to match the TPI, because it takes longer for an LT-1 to get to its peak. Whereas a long runnered 383 TPI for example would make its 400 hp peak at 4800 rpm... a 400 hp LT-1 more towards 5800 rpm..... that tpi would rev much quicker than the LT-1 motor.

As far as top speed, I doubt if either car could pull to its hp peak in top gear anyway.... probably very close to trap speeds.

I know a lot of people like to talk about getting more rpm out of their motors.... and this will typically give you more hp potential, but in reality, you want to make as much hp as you can as quickly as you can in the rpm range..... however to make the type of hp we would all like, we need to either run a lot of cubes or a lot of rpm.

food for thought
Todd

 

The TPI will not beat the LT1 and here is the reasoning. If you look at the dyno charts of both motors the TPI will put out its peak very early and have its power slide away after that. You'll get hung out to dry in your last gear. The majority of your power will most likely be lost due to traction problems. The LT1 the other hand is NOT totally devoid of torque like some people think. Have you heard LT1 guys complain of no torque? The LT1 will move the power band into the higher RPM range and make power after you've hooked up on the pavement and won't quit after 3 grand in your last gear. The LT1 powerband is also flatter which makes for more consistent power rather than the TPI ups and downs. This is what is meant by "useable horsepower". You'll get better times by having your power in higher bands than having in right off the line and resulting in traction issues. Don't get me wrong a 400hp TPI is nothing to take lightly, but a 400hp LT1 is not only a faster car but an easier car to get to 400hp.

 

Iroc n Roll,

I am sorry, but you are wrong. A 400 HP TPI will accelerate faster than a 400 HP LT-1 with all other vehicle variables equal between the two.

As a note, its pretty easy to hook-up your 400 HP TPI motor... nothing a set of ET Streets cannot solve.

Look at this way.... forget about rpm.... think just about the power that you have available to you at any given amount of time. I will give you an example.

Lets say 2 identical 3rd gens each have a raceweight of 3500 lbs, a torque converter that flashes to 2800 rpm and 3.45 gears.

However the TPI motor makes its peak torque at 3500 rpm with 450 ftlbs of torque and its HP peak of 400 HP at 4800 rpm. (This is approxmiately what a LPE 383 with Accel large runners, 74211 and heavily ported D-port heads will make)

The LT-1 motor makes its peak torque at 4500 rpm with 420 fltbs of torque and its HP peak at 5800 rpm with 400 HP (This is approxmiately what a fairly well running 350 LT-1 with good heads and agressive cam could make)

Upon sticking the pedal to the floorboard, the TPI would hit 2800 rpm and then accelerate to roughly 4500 rpm after 2 seconds and would have just about 380-390 hp at your disposal after these 2 seconds... at this point with sticky tires, you have already gone past the 60 foot mark and you are getting ready to hit 2nd gear. The TPI revved faster than the LT-1 because it has more torque down their and its hp peak came up much quicker.

Lets say the LT-1 also somehow revved as quickly as the L98 to 4500 rpm after 2 seconds, however after 2 seconds and only at 4500 rpm, it is still a long ways from its HP peak and only has roughly 360-370 hp at that point...... it has not accelerated as hard as the TPI motor.... it cannot, it is impossible. Forget about rpm..... think about time and the hp you have under your foot.

This is why LT-1's respond better than TPI motors to lots of converter stall and gear.... they have their peaks higher, thus they accelerate slower to the #, therefore gears and higher stalls artificially push them past the low rpm area's. I would guess that if the LT-1 had another 200 rpm of stall and/or upgraded from the 3.45 to 3.73 gears, then it would be a toss up as to which one wins the race..... keep in mind the TPI motor has a big advantage against other motors of equal TOTAL power... and that is that the power is off idle and you are quickly into your power right away.... TPI motors do not need gobs of gear to push us through our low to midrange torque curve. Remember it takes torque to rev...without torque your motor will just sit their and idle and the vehicle with the most torque will accelerate the fastest.

If you want to look at average torque... I think you would see the TPI would also have more average torque in this scenario considering the slap back rpm on the shift changes will put the rpm back to roughly 3500 rpm right at its torque peak of 450 ftlbs with a 5200 rpm shift. (This is assuming a 1700 rpm slapback window which is pretty close for a street motor) The LT-1 would slap back to roughly 4500 rpm where it too has its torque peak, but a bit less at 420 fltbs of torque.... this is with a 6200 rpm shift.)

You don't have to believe me....but every engine builder that is in existance knows and understands this very fundamental issue.

On the flip side... its much easier to make HP with LT-1's... but I don't think this is being debated. In addition, you can typically make LT-1's go faster than TPI motors because you can build more power through rpm..... but this also is not being debated either. In your example, both had 400 HP.

food for thought
Todd

 

um i beg to differ an l98 with a 20 hp deficit to an lt1 can beat the lt1. I have done it many times tell you what a 2.0 60 footer vs a 2.2 60 footer. torque gets you through the 60 foot quicker. and you are pulling on the lt1 up untill you go through the 1000 ft mark

 

It's all a matter of making sure you set up your car to work together. Remember there are a lot of other factors affecting quarter times. Read GEARING, also tire size, what tranny, shift points, what torque converter, weight, etc. A car that makes 400 ft/lbs of torque at 2500 rpm would do better with a longer gear ratio, lower shift points, and lower stall speed. A car that makes the same 400 ft/lbs of torqe at 4500 rpm then you'd want more gear, torque converter, and higher shift points. So plan in advance and select parts that will work together.

A perfect example of this is my cutlass. The 455 is built for power below 5500 rpm. It runs much quicker with 3.08's than it did with 3.73's and I shift at 5000. Or my corvette that redlines at 7000, but sucks with anything less than 3.55's and 6500 shifts.

Having said this however, their is a reason that the pros build there engines to run at RPMs that would be ridiculous to the rest of us. But their cars won't run on the street.

One other factor of course is do you like to do big smokey burnouts ?
John