Best way to upgrade 455?

[bkachel]

Hello,

New to the forum. I recently purchased a 1973 Trans Am 455. The engine as 38k original miles on it. I'd like to add some more power without blowing it up. Would some of you be willing to help me out with this? I'm not looking to take it to the race track, but I sure wouldn't mind a high powered street car. Whats the maximum I can do with pumping normal gas and getting some good RPM's out of it? A complete build items list would be great with reputable brands and makers. Lets build this sucker! 

Any help would be appreciated. Thanks.
-Brandon

[80Pacer]

I think that most people here are going to ask you exactly what use you have planned  for the car, how much power are you looking for, and how fast do you want to go? That engine is easily capable of 14 second times in the quarter with very minor mods. are you looking for a 13 or quicker car? Also are you worried about top speed or just want fast acceleration? Give us an idea and you will be blessed with a multitude of answers.

[Jack]

I would also look up and include the casting and head numbers, to both confirm what you have and allow the few TAC experts to give you advise.

[jonathonar89]

Power adders are king but probably won't be considered in this situation...most Pontiac guys don't go that route.  Turbocharger would be badass.

[oldskool]

"...Whats the maximum I can do with pumping normal gas and getting some good RPM's out of it? A complete build items list would be great with reputable brands and makers..."

Not the "maximum" by any standards, but a build similar to the Len William 455 crate engine is a good guideline for a basic 400hp + build.

http://lenwilliamsautomachine.com/455_Long_Block.html

Then you can add H-beam rods, lighter pistons, a bigger(or roller) cam, alum heads, maybe an 800cfm SMI Q-jet on a stock '72 intake, or a Chinese single plane. If you like Holley carbs, you can go with a big Holley type carb & a Torker 2 intake.

Well, the possible upgrades are almost endless. Depends on your budget and EXACTLY what you want from the engine.

[nas t eh]

I almost always agree with oldskool on questions like this, and he has given you an example of a good starting place. We can provide more specifics as we learn more about what you really want.

You bought a fairly low mile, nearly original, nicely restored 1973 455 T/A 4 speed. You paid for it and can do what ever you want, but you might want to be careful not to loose your investment.  If your car is # matching or mostly so, replacing any of the parts on the motor or car and not keeping the removed pieces would be a $$$ mistake.

If # matching, you really might want to pull that motor and save it. Then buy or build one and drop it in.

If it were me, doing it over with mine, I would set the budget and HP level first. Your at 250HP stock, 350 -450HP is fairly easy and reasonable money, not too hard on all the other drive train parts, so leaving them stock at those levels is a reasonable option. Somewhere at or above 450HP nearly everything else needs to be upgraded too.

On your stock 455 the really weak areas are oiling, connecting rods and pistons but you can still make 450 HP with them in place, if you want, thou some or maybe most would recommend upgrading them as well.

The easy recipe to add power would be new heads, cam, intake and exhaust, with a tune on the distributer and carb or replace them too. The problem is new or rebuilt heads may result in oil consumption as the old piston rings can't keep up to the seal from the new valves in the heads.  So then you are back to doing the short block and should upgrade its weak areas while at it.

So back to the question of budget and HP

Do you add 100HP for something like $500-$1500, 200HP for $2000-4000, 300HP for $7000-10,000. These prices are by no means exact, just kind of ball parks. If you're not doing work yourself and want a really good job, their likely low, especially at the higher HP levels as you really need to upgrade other things too.
 

[nas t eh]

I just remembered something you should be aware of.

The RPM redline for that stock 455 motor is about 500rpm lower then indicated on the factory tach. Do not over rev it unless you really want to rebuild that motor. I found out the hard way.(twice)

[jonathonar89]

I just remembered something you should be aware of.

The RPM redline for that stock 455 motor is about 500rpm lower then indicated on the factory tach. Do not over rev it unless you really want to rebuild that motor. I found out the hard way.(twice)

Which tach...the 6k or 8k version? 

[bkachel]

I almost always agree with oldskool on questions like this, and he has given you an example of a good starting place. We can provide more specifics as we learn more about what you really want.

You bought a fairly low mile, nearly original, nicely restored 1973 455 T/A 4 speed. You paid for it and can do what ever you want, but you might want to be careful not to loose your investment.  If your car is # matching or mostly so, replacing any of the parts on the motor or car and not keeping the removed pieces would be a $$$ mistake.

If # matching, you really might want to pull that motor and save it. Then buy or build one and drop it in.

If it were me, doing it over with mine, I would set the budget and HP level first. Your at 250HP stock, 350 -450HP is fairly easy and reasonable money, not too hard on all the other drive train parts, so leaving them stock at those levels is a reasonable option. Somewhere at or above 450HP nearly everything else needs to be upgraded too.

On your stock 455 the really weak areas are oiling, connecting rods and pistons but you can still make 450 HP with them in place, if you want, thou some or maybe most would recommend upgrading them as well.

The easy recipe to add power would be new heads, cam, intake and exhaust, with a tune on the distributer and carb or replace them too. The problem is new or rebuilt heads may result in oil consumption as the old piston rings can't keep up to the seal from the new valves in the heads.  So then you are back to doing the short block and should upgrade its weak areas while at it.

So back to the question of budget and HP

Do you add 100HP for something like $500-$1500, 200HP for $2000-4000, 300HP for $7000-10,000. These prices are by no means exact, just kind of ball parks. If you're not doing work yourself and want a really good job, their likely low, especially at the higher HP levels as you really need to upgrade other things too.
 

oldskool sent me a bunch of links of motors I can buy and drop in. I will budget accordingly for whatever I have to do. Cams, heads etc. My biggest concern is not doing it right at the beginning and causing a world of problems later. Preferably I'd like to get in the 500-550 hp level with the option of adding more power later if that's a route I'd like to take. Both you and Oldskool seem to think it's best to do a completely new rebuild. Maybe that's the way to go.

[jonathonar89]

Oldskool is right in the fact that the upgrades are endless. 

My favorite combo of induction parts to see would be a Torker II intake, FiTech or Holley TBI, and PTFB air cleaner.  A locked out MSD type of distributor can be used to apply computer controlled ignition...recommended if you go efi.  Ram Air Resoration cast headers or Tribal Tubes Tri-Y headers are the most preferred exhaust systems for Pontiac engines currently.  All the parts above can be bolted onto your engine as it is now and grow once you step things up to the 550hp range.

[nas t eh]

I just remembered something you should be aware of.

The RPM redline for that stock 455 motor is about 500rpm lower then indicated on the factory tach. Do not over rev it unless you really want to rebuild that motor. I found out the hard way.(twice)

Which tach...the 6k or 8k version? 

Good question, been a while since I even looked at it. IIRC the tach has the yellow bar at 5250rpm and red at 5750rpm on mine and I think it's the 8000rpm one and it would be fine for the 400ci motors. But the large main journal block motors(421,428,455ci) usually need over 60psi oil pressure to overcome the larger centrifugal forces created at the larger journal at higher rpms. The regular 455 in 73 did not come with a very good oil pump and somewhere around 5300 to 5500rpm things can start to go wrong. Yes I spun mine past that a few times before the knocking started (I'm sure it hit 6000+ once or twice, don't miss a shift in a 4 speed car) but 5750rpm is not a good limit for that motor. During the rebuild process(I had two motors to do) I read the H-O racing specialties book and found out why I had so easily got a knocking rod.

[nas t eh]

I almost always agree with oldskool on questions like this, and he has given you an example of a good starting place. We can provide more specifics as we learn more about what you really want.

You bought a fairly low mile, nearly original, nicely restored 1973 455 T/A 4 speed. You paid for it and can do what ever you want, but you might want to be careful not to loose your investment.  If your car is # matching or mostly so, replacing any of the parts on the motor or car and not keeping the removed pieces would be a $$$ mistake.

If # matching, you really might want to pull that motor and save it. Then buy or build one and drop it in.

If it were me, doing it over with mine, I would set the budget and HP level first. Your at 250HP stock, 350 -450HP is fairly easy and reasonable money, not too hard on all the other drive train parts, so leaving them stock at those levels is a reasonable option. Somewhere at or above 450HP nearly everything else needs to be upgraded too.

On your stock 455 the really weak areas are oiling, connecting rods and pistons but you can still make 450 HP with them in place, if you want, thou some or maybe most would recommend upgrading them as well.

The easy recipe to add power would be new heads, cam, intake and exhaust, with a tune on the distributer and carb or replace them too. The problem is new or rebuilt heads may result in oil consumption as the old piston rings can't keep up to the seal from the new valves in the heads.  So then you are back to doing the short block and should upgrade its weak areas while at it.

So back to the question of budget and HP

Do you add 100HP for something like $500-$1500, 200HP for $2000-4000, 300HP for $7000-10,000. These prices are by no means exact, just kind of ball parks. If you're not doing work yourself and want a really good job, their likely low, especially at the higher HP levels as you really need to upgrade other things too.
 

oldskool sent me a bunch of links of motors I can buy and drop in. I will budget accordingly for whatever I have to do. Cams, heads etc. My biggest concern is not doing it right at the beginning and causing a world of problems later. Preferably I'd like to get in the 500-550 hp level with the option of adding more power later if that's a route I'd like to take. Both you and Oldskool seem to think it's best to do a completely new rebuild. Maybe that's the way to go.

It is if 500+ HP is what you really want. If you want a 100HP bump you could do that with stock heads still in place easy so no rebuild required.

[Aus78Formula]

Is the 500-550hp level just a nice figure to tell people? If it was dyno'd at 400hp would you know the difference? If low miles and good condition as is, I'd simply go for bolt-ons and not open the motor up too much, and be realistic with the goals.

[oldskool]

"...Is the 500-550hp level just a nice figure to tell people?..."


These figures can be easily(but not cheaply) reached, with stock block Pontiac engines. BUT, VERY FEW actually NEED that much power, on street tires.

[Formula8]

Agreed, I think my current motor is near 550hp and with a stick, my gear and a street tire.........it is pretty useless.  Not just in first, but in second and half of third.  I have spun two bearings just trying to get things sorted out but in all fairness, my motor has seen 6500+ RPM prompting the purchase of a MSD 6AL with rev limiter. 

When I read the original post, I was thinking a decent rear gear, posi unit, torque converter and relatively sticky tire.  From there, while I was putting in a mild street cam and porting the stock manifold, I would send the Q-jet out to be hot rodded or replaced with a SMI version and recurve the distributor.  I would add a Pypes crossflow exhaust with X-pipe.  My bet is we could have the car deep into the 13's, keep the bearings and rods in the block and look bone stock under the hood. 

[nas t eh]

Brandon, you might want to make sure the car is properly tuned and just drive it for a while. All those years ago when I first bought mine, it was out of tune. Timing was actually 2 degrees ATDC and carb was a little off too. Car ran OK, but nothing special. New points, plugs and wires, timing set to spec or a little ahead.( I can't remember but 12 degrees BTDC comes to mind) and the car woke right up. It was a blast to drive.

If you don't think its fast enough after a while, do the easy stuff first. Cam, intake, exhaust, get carb rebuilt buy Cliff, and the distributor rebuilt and recurved. This will be a reasonably small investment, get you to 350 or more HP, you can drive that for a while and probably find it's plenty.

Later if it's still not enough, you wouldn't loose too much to get to the next level because you could keep the intake and exhaust investment for sure and likely the distributor would be fine too. You might or likely would replace the cam on the next HP bump and likely would retune the carb, but you would be getting the heads done or new ones at that point and likely rebuilding the whole motor as well, so who cares about loosing the cost of a flat tappet cam and lifters.

[bkachel]

Brandon, you might want to make sure the car is properly tuned and just drive it for a while. All those years ago when I first bought mine, it was out of tune. Timing was actually 2 degrees ATDC and carb was a little off too. Car ran OK, but nothing special. New points, plugs and wires, timing set to spec or a little ahead.( I can't remember but 12 degrees BTDC comes to mind) and the car woke right up. It was a blast to drive.

If you don't think its fast enough after a while, do the easy stuff first. Cam, intake, exhaust, get carb rebuilt buy Cliff, and the distributor rebuilt and recurved. This will be a reasonably small investment, get you to 350 or more HP, you can drive that for a while and probably find it's plenty.

Later if it's still not enough, you wouldn't loose too much to get to the next level because you could keep the intake and exhaust investment for sure and likely the distributor would be fine too. You might or likely would replace the cam on the next HP bump and likely would retune the carb, but you would be getting the heads done or new ones at that point and likely rebuilding the whole motor as well, so who cares about loosing the cost of a flat tappet cam and lifters.

 I have been talking with oldskool as well and he has me convinced to do an entire swap, but I am definitely going to make sure it is properly tuned first thing.