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Old 03-30-2006, 10:19 AM
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Choose Pontiac 400 or 455? & Turbo Questions

Long time reader, first time poster. Hi.

I am in the process of planning my first full project car. I'm at that part of life where I'm starting to have a little extra time, and I can budget a project properly. My plans are to customize a 65-67 Pontiac. I'd like to find a Tempest or Lemans and create a GTOish look, but not a clone.

I want to get started now on building the engine and trans up first so that I can spend several months finding the right car to host them. I want to build a fuel injected motor with the idea that I can put a turbo system on it in the future. I am considering either a 400 or 455. Street machine. I would like my wife or daughter to be able to get in and drive without rolling their eyes.

Questions-
Suggested reading on learning about EFI systems?
Required reading for new Pontiac guys?

Edelbrock sells a Torker EFI manifold which is advertised as good up to 6,500 rpm. Torker is known for rough idle (performer better for idle).... is this a non-issue with EFI? Would the Torker EFI manifold have a smooth street idle, or should I fabricate EFI onto a stock or performer?

Can I build an EFI motor with cam and compression that will carry over to the turbo project, or is a non-turbo turned turbo motor require major changes? (I'm okay with a lowish compression EFI motor while waiting for turbo).

I'm wondering which motor is better choice- 400 or 455. Any thoughts on pros / cons of the two? I'm thinking that if I want to end up turbo, that the torque from the 455 would put me into a whole new league for drive train. Except that 455 is known for low end torque, and turbo would be kicking in more higher on the curve? Maybe the perfect match?

Transmission- Pardon my ignorance; Would the 400THM be the right tranny to look for?

Thanks in advance.

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Old 03-31-2006, 11:24 AM
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I'm not a Pontiac guy, but I'll try to help with some links and ideas. Blower Drive Service makes some pretty slick EFI systems using existing manifolds. http://www.blowerdriveservice.com/
Here's a list of turbo info I gathered a while back....
http://streetmachinesoftablerock.com...topic.php?t=83

This table from Stan Weiss shows bore, stroke, rod length, rod/ stroke ratio and bore/stroke ratio. Scroll down to Pontiac. The 400 uses a bore/stroke almost identical to the 400 small block Chevy, while the 455 uses a gargantuan 4.210" stroke. You'd certainly want to build that motor for low rpm's to keep from runnin' over the crank.
http://users.erols.com/srweiss/tablersn.htm
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Old 03-31-2006, 12:42 PM
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As far as turbo and efi, check out this megasquirt computer www.megasquirt.info and www.msefi.com

They are dyi efi AND ignition controllers, they do take some work and you have to have a little electronics knowledge, i am on my 3rd project that run perfectly and i'm not an electronic engineer. They are very cool and alot less expensive than a standalone system.

As far as bulding the engine for the turbo, if you keep the boosts pressure low(under 10psi) you can get by with almost stock engine. 10 psi will almost double your horsepower, but definatly go for bigger injectors off the bat as well as a rising rate fuel pressure regualtor, i would also run the edis ingnition system off of megasquirt.

Brendan
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Old 03-31-2006, 12:55 PM
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Thanks for the replies. I ordered a few books on the subjects, so I'll spent a few weeks planning.

There are 2 things that I really want to accomplish; 1 is to do the engine assembly myself, and 2 is to successfully put EFI on it. Turbo is later in life, but if I can get 1 & 2 done, I'll be ready to conquer the world (btw, it would be <= 10 psi). The reason I want to do these things, is because I want to learn as much as possible.

Quote:
Originally Posted by sha_ba_do_bang
As far as turbo and efi, check out this megasquirt computer www.megasquirt.info and www.msefi.com

They are dyi efi AND ignition controllers, they do take some work and you have to have a little electronics knowledge, i am on my 3rd project that run perfectly and i'm not an electronic engineer. They are very cool and alot less expensive than a standalone system.

As far as bulding the engine for the turbo, if you keep the boosts pressure low(under 10psi) you can get by with almost stock engine. 10 psi will almost double your horsepower, but definatly go for bigger injectors off the bat as well as a rising rate fuel pressure regualtor, i would also run the edis ingnition system off of megasquirt.

Brendan
I've already figured on using the Megasquirt system. I would purchase an assembled unit though. I can wrench, and I can use the software, but I sure can't solder!

Any thoughts on whether the Torker EFI manifold would work well at idle?

Thanks, Scott.
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Old 01-27-2009, 06:56 PM
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Scott,

There are a couple of builds that I know of that have completed what you are looking at. I am in the process of putting a TV7101 on a 455 Pontiac in a 67 Bird. I have several friends that have running cars that you could use as a point of reference for turboing a Pontiac. Big thing to remember is that blocks are good to about 750 hp and 1000 if you put filler in the water jackets. Nodular cranks are just about indestructable and scat or eagle or ohio rods are fine. Billett Main caps are a good idea but not critical. Main studs are a good investment as well as a good set of Ross or JE Pistons. Compression needs to be about 8-1. Can be achieved with a 4X - 1H head (114cc 2.11I 1.66E). Cam selection needs to be a mild cam with lobe centers around 114 and duration probably under 240 @.050 with lifts in the lower 500's with a split pattern with a higher exh lift (that is a whole debate in head flow itself!)

I know these combinations with an S400 or TV7101 have produced 800+ hp and pushed 3500 pound cars in the high nines on 11 lbs of boost. Does not take a lot of boost if you match the turbo sizing with your head and cam choice.

Here is a link to another build that you can use as a reference point:
http://www.pontiaczone.com/forum/showthread.php?t=20819

Hope that helps.
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Old 01-27-2009, 07:09 PM
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Quote:
Originally Posted by TheMonkey
Long time reader, first time poster. Hi.

I am in the process of planning my first full project car. I'm at that part of life where I'm starting to have a little extra time, and I can budget a project properly. My plans are to customize a 65-67 Pontiac. I'd like to find a Tempest or Lemans and create a GTOish look, but not a clone.

I want to get started now on building the engine and trans up first so that I can spend several months finding the right car to host them. I want to build a fuel injected motor with the idea that I can put a turbo system on it in the future. I am considering either a 400 or 455. Street machine. I would like my wife or daughter to be able to get in and drive without rolling their eyes.

Questions-
Suggested reading on learning about EFI systems?
Required reading for new Pontiac guys?

Edelbrock sells a Torker EFI manifold which is advertised as good up to 6,500 rpm. Torker is known for rough idle (performer better for idle).... is this a non-issue with EFI? Would the Torker EFI manifold have a smooth street idle, or should I fabricate EFI onto a stock or performer?

Can I build an EFI motor with cam and compression that will carry over to the turbo project, or is a non-turbo turned turbo motor require major changes? (I'm okay with a lowish compression EFI motor while waiting for turbo).

I'm wondering which motor is better choice- 400 or 455. Any thoughts on pros / cons of the two? I'm thinking that if I want to end up turbo, that the torque from the 455 would put me into a whole new league for drive train. Except that 455 is known for low end torque, and turbo would be kicking in more higher on the curve? Maybe the perfect match?

Transmission- Pardon my ignorance; Would the 400THM be the right tranny to look for?

Thanks in advance.


Almost missed your questions.

Either is fine 400 or 455. 75 and later 455's are a little weaker but I know of one that is making 878 hp and is fine. 400's have a smaller main journal which is a good thing on Pontiacs and can be border to make 455 cubes easy. 455 Cranks can be made to turn down to fit a 400 block but if you have the 455 then just use it and keep rpms under 6000 and you are fine. Pontiacs do not like RPMS and the heads won't flow so utilize their torque by camming and gearing to your advantage. Tall 3.00 to 3.23 gearing and a mild cam makes a strong turbo motor.

EFI is a good thing and tunability is way better if you have the $$. Megasquirt is a great system and would be my first choice. Intakes are different. The old style torker is not the best turbo intake but the Victor EFI is a great one if you have the hood clearance. You could also take a Torker II and put the nozzles in that intake if you have a drill press and some patience. Or farm it out.


You can go as mild as you want just don't go cheap on your fuel system! You can go rich and foul plugs and never hurt anything but you will only go lean once! Then its goodnight, partys over. Excessive heat from lean temperatures combined with boost = blown head gaskets or pistons with wholes in them! Very Bad!

Keep your combo mild and build your fuel system to make 1500 hp and you will never out grow it. Trust me, boost is addictive and very tempting!

Best of luck.
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Old 01-27-2009, 07:45 PM
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Quote:
Originally Posted by TheMonkey
Long time reader, first time poster. Hi.

I am in the process of planning my first full project car. I'm at that part of life where I'm starting to have a little extra time, and I can budget a project properly. My plans are to customize a 65-67 Pontiac. I'd like to find a Tempest or Lemans and create a GTOish look, but not a clone.

I want to get started now on building the engine and trans up first so that I can spend several months finding the right car to host them. I want to build a fuel injected motor with the idea that I can put a turbo system on it in the future. I am considering either a 400 or 455. Street machine. I would like my wife or daughter to be able to get in and drive without rolling their eyes.

Questions-
Suggested reading on learning about EFI systems?
Required reading for new Pontiac guys?

Edelbrock sells a Torker EFI manifold which is advertised as good up to 6,500 rpm. Torker is known for rough idle (performer better for idle).... is this a non-issue with EFI? Would the Torker EFI manifold have a smooth street idle, or should I fabricate EFI onto a stock or performer?

Can I build an EFI motor with cam and compression that will carry over to the turbo project, or is a non-turbo turned turbo motor require major changes? (I'm okay with a lowish compression EFI motor while waiting for turbo).

I'm wondering which motor is better choice- 400 or 455. Any thoughts on pros / cons of the two? I'm thinking that if I want to end up turbo, that the torque from the 455 would put me into a whole new league for drive train. Except that 455 is known for low end torque, and turbo would be kicking in more higher on the curve? Maybe the perfect match?

Transmission- Pardon my ignorance; Would the 400THM be the right tranny to look for?

Thanks in advance.
As was said, the pre '75 400 block is stronger in the main webbing than a 455 block. To use a turned down 455 crank in a 400 block you must use a spacer for the thrust bearing. Ken Keefer at http://www.angelfire.com/fl4/pontiacdude428/
has been making a kit for this insallation, but most of the Pontiac venders are selling stroker kits for the 400 block, with either forged or cast crank, steel rods in either 6.8" or stock 6.625" length, and custom forged pistons. If you'd like more Pontiac specific vender websites, PM me.

Bill

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Old 01-28-2009, 09:26 AM
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Last edited by ssonny34@yahoo.com; 01-29-2009 at 11:11 AM.
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Old 01-28-2009, 10:07 AM
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I know of poncho 400 blocks that spin past 6500 with regularity. It all depends on how they're built. The 6000 rpm limit on a pontiac is a wives tail caused by improper builds.
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Old 01-28-2009, 11:03 AM
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Quote:
Originally Posted by wmhjr
I know of poncho 400 blocks that spin past 6500 with regularity. It all depends on how they're built. The 6000 rpm limit on a pontiac is a wives tail caused by improper builds.
That is correct. 326, 350, 370,389,400 all use the same stroke and have the same main journal size. 421,428 use the same crank and the 455 uses the longest stroke while all three use the larger main journal sizing. 400's Rev easier and are no problem past 6500 with ARP Rod Bolts and a good set of forged rods. Oiling is the problem at higher rpms on the 455's. I had a set of SD455 rods in a 455 with a solid cam and would spin it to 7200 without any breakage. Problem is the heads don't flow enough to make it worth while so its better to cam differently and take advantage of the torque.

Stock rods are ok but they are your weak link.
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Old 01-28-2009, 12:15 PM
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Use low impedance injectors. Which takes a special injector driver.

You need low impedance because a turbo engine needs a very wide range of fuel delivery and low impedance injectors work well at very low duty cycles (which is needed for idle).

FYI
7.5 psi will increase torque and hp by 50%
10 psi by 68%
15 psi by 100%

so in theory, if you start with 325hp/400 ftlbs then you will get 490hp/600ftlbs at 7.5psi of boost.

if you use small turbines for low rpm boost (2500-3000 rpm) then use a cam with very minimal overlap. This is because small turbines make a lot of exhaust back pressure and you need to prevent reversion into the intake system. And use more intake duration than exhaust with lots of lobe separation.

If you use bigger turbines for higher rpm boost (3500+ rpm), then you can use a cam with more overlap.

For a easy to drive street car, I would build a 455cid with 7.5:1 cr and run about 8 to 10 psi of boost. Install a cam with 214 on the intake and 208 on the exhaust with 114 LSA. Use a couple of Buick Grand National turbos (3.8 liter). Eight 500cc low impedance injectors should be enough. Use megasquirt II with ignition timing control. Ignition timing control is very important for a turbo engine because a lot of retard will be required while on boost.

A LSD 3.08 gear, thm400, and a heavy duty towing converter should work fine for a 455 cid turbo street car.

Yes, a torker intake will work well for an efi system.
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Old 01-28-2009, 01:11 PM
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Just playing the bad guy here... have you considered a Buick 455 or a Caddy 500? The buick will make the same power and torque with the ability to rev a little safer. The Caddy is just a behemoth, but its much lighter than any of the other big block GMs, and its strong point is that it doesn't need to rev. Massive torque and 400+ hp are easily attained below 4500 rpms. Ultimate street muscle car engine if you ask me.

Just tossing that out there

(like a steak into a dog kennel)
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Old 01-28-2009, 01:56 PM
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The lower gear rations (3.08) is correct. The turbo has a flat power band and workds off load to create boost. Reving the engine has adverse affect if the heads will not flow higher. Kind of like putting your thumb over the end of a garden hose. The water comes out faster but the quantity is not increase any just the pressure. If you have bigger ports and it can work at a high velocity and at high rpms then that is a different story. Most pontiac D port heads are pretty much done after 5000 rpms maybe to 5600 but the power will fall off after that. If you can run your boost and build pressure and hold the power band lower and longer then there is no need to rev at all. The caddy 500 I could not say for but buicks had an oiling issue that is far worse than Pontiacs. Interchangability is another advantage to Pontiac. All the rods, intakes, heads, timing covers, cams, exh, distributor, valvecovers, waterpumps, and many other items interchange with the exception of 64 and back and the 301 (used in the 80-81 Turbo TA). Plenty of aftermarket heads out there that flow over 300 cfm now so if you want RPM and can spend the $$ you can but you should not have to.
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Old 01-28-2009, 02:45 PM
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I'll never bash anyone for suggesting different engine combos. But, I'm wondering if people really understand the torque that the Pontiacs produce. BTW, the Pontiac isn't a "GM Big Block". It's a Standard Block. When you look at the weight of the Poncho 455 vs the Buick 455 vs the Caddy 500, there is almost no weight difference. Add to this that you're not going to be able to find KRE, Edelbrock, Roland or Wentzler aluminum heads for the others.

I can't begin to list all the extremely easy to build Poncho combos that break 400hp with incredibly reliability and safety.

I have to admit that when I started my project, I seriously thought of transplanting a Chevy BB in it because of all the build options that opened up, and the reduced cost. But the only reason I'd use a Buick or Caddy motor would be if I were building a Buick or Caddy.
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Old 01-28-2009, 03:49 PM
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Quote:
Originally Posted by wmhjr
I'll never bash anyone for suggesting different engine combos. But, I'm wondering if people really understand the torque that the Pontiacs produce. BTW, the Pontiac isn't a "GM Big Block". It's a Standard Block.
I don't think people really understand that torque is not really affected by stroke as much as you'd think. A buick 455, olds 455, and pontiac 455 set up the same will all make the same basic torque and hp at the same RPMs. I just personally prefer the larger bore, shorter stroke engines for their future potential. I build a lot of engines, and under 5000 rpm they'll all be about the same, but if you plan on going big with RPMs the money you sink into rods and crank on the longer stroke engines to combat the exponential piston acceleration can pretty easily offset the cost of just using a different engine. The cost of buying a P455 is often pretty inflated. A caddy costs about the same as a core, but its only about the same cost to build as a BBC as long as you stay under 5000. Above 5000 they start getting expensive.

I'll also double check my sources, but I have about 600 lbs for the caddy and buick, but 685 for the Pontiac. Plus, the caddy will weigh about 40 lbs less with an edelbrock intake. Bulldog makes killer heads for caddys too.

I'm not arguing my point - the pontiac is a great engine and you will do well with it, just letting you know why I suggested those.
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