Pontiac - Boost Turbo, supercharged, Nitrous, EFI & other Power Adders discussed here.

          
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  #21  
Old 02-11-2021, 05:37 PM
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Originally Posted by mike_dmt View Post
Thanks again for the input guys, I do appreciate it!

Personally, I feel that in the long run, any time you're looking to make a good bit of power is just going down the rabbit hole. Where does it stop? You can throw a lot of cash in that hole trying to get somewhere you don't really need to be.

I'm not chasing any specific horsepower numbers, but I'm thinking a little north of 600 would be good enough in a heavy street driven LeMans. Because much over that, any budget you've got gets thrown out the window to make the rest of the parts hold up for any amount of time.

If I'm hearing you guys right, it sounds like a guy could do that pretty safely on the stock block and crank.


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Last edited by 455dan; 02-11-2021 at 05:48 PM.
  #22  
Old 02-11-2021, 07:12 PM
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Originally Posted by mike_dmt View Post
...Personally, I feel that in the long run, any time you're looking to make a good bit of power is just going down the rabbit hole. Where does it stop? You can throw a lot of cash in that hole trying to get somewhere you don't really need to be...
As stated by others, LS has much more room to grow.
A 5.3 iron block is strong as hell and as also stated research and proven parts are easy.

455 Dan: my LS3 transplanted TA get far more interest than a Poncho powered Pontiac at a gathering.

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Old 02-11-2021, 08:43 PM
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As stated by others, LS has much more room to grow.
A 5.3 iron block is strong as hell and as also stated research and proven parts are easy.

455 Dan: my LS3 transplanted TA get far more interest than a Poncho powered Pontiac at a gathering.
I must have something wrong with me .

example "Overhaulin"

They open the hood on any Pontiac, Buick or Old's and a gleaming LS SBC between the frame rails.
Literally get a sinking feeling, feel ill.... especially any car that actually had a 400,401, 425, 428, 430 or 455 IN the car when they "took" it.

I should seek professional help,

Accepted Ponchos cost more to build than SBC.

I don't hate SBC's had a 9C1 police Caprice with LT1 and put 90000 on top of the 110 K it had when I got it. It was a Great running hiway cruiser. Never owned a new LS but am sure they run even better.
Will be watching with interest what the OP decides to do, and wish him a successful build of a 600+ HP power plant, regardless of what he choses, but I hope he chooses the Pontiac build.

  #24  
Old 02-12-2021, 02:53 AM
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At this point I definitely have some decisions to make.

I really expected more backlash AGAINST putting an LS in there, but it seems like guys are 50/50 on it. (At least in the Boost section of the board).

And since it started life as just a bench seat, post car, the resale isn't really a factor in any decisions I make.

On the tech side of it, what sort of compression ratio should I shoot for with a Pontiac build? Any cam suggestions?

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Old 02-12-2021, 11:26 AM
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LS or Pontiac, it is your car. Do it how you want and don’t look back. I think it is cool your considering a pontiac.

This is a Pontiac forum. Boosted LS probably would have more input on a LS forum. Above 700 hp without a chassis to put the power to the ground pretty much a waist of time on the street. Unless of course your after big HP Dairy Queen bragging rights. Lol

I am one of the guys that enjoys seeing period correct parts on vintage cars. Not always, but I think it is cool when it is possible and can meet the goals for the car.

So since you have 48 heads and have a 68 lemans that would actually be my first pick. But like I suggested, 6x might be more budget friendly, and already have induction hardened seats. If 48 heads are the common 66cc variety 48s would need a 28cc dish to get the compression down to about 9:1. I know DSS has that option, just helped on a ra4 that had them. Probably put harden exhaust seats in the 48s and new stainless valves. Have the shop open up the throat on the intake valve to 1.7 and switch to 45* seats. Pro touring I think I would stay close to 9 so it still has decent eff when not utilizing boost. If you were searching for more power to would drop the SCR and add some more boost. At around 600-700 hp I think 9 is pretty reasonable for that goal. We have dropped down to the upper 7s with boost and did not notice a big drop in drivability. Two good off the shelf very economical HFT cams for boost in a 400 are the summit 2802 (224/234) and the melling SPC-8 (231/240). Both will like some advance with boost. For 600hp the ra 4 Spc-8, 1.65s with Rhoads v Max’s would be my pick. Above those hp levels I would do a Bullet custom solid cam with a 4/7 swap.

FWIW. The Macho Turbo Trans Am was stock and advertised at 325 hp with 7 lbs boost. That was a totally stock long block with a blow thru qjet with the factory cats and exhaust. I think the 325 rating was based off the 220 hp and 7 psi boost. So engine flywheel hp that turbo engine was likely well over 400 hp. Just building from that engine, shooting for 600 hp, adding mains studs, forged rods and pistons, more cam, mls gaskets , plus a better turbo, and for cheap insurance add a meth injection,a fi system or decent blow thru carb....pretty much gets you past 600.


Last edited by Jay S; 02-12-2021 at 11:29 AM. Reason: Err
  #26  
Old 02-12-2021, 01:20 PM
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Tom, could you in good conscience recommend to the OP to put 862 horsepower on his stock Pontiac block and crank? Expected lifespan? 6-8 psi may be a very appropriate range for this to keep things together.
The engine that Luhn Performance ran was not a aftermarket block, it was a basic early 70s 455 engine block with some good rods and I believe one of Wade and Mark's BOP forged cranks.

So to answer your question, after we tore it back down for a engine inspection the only issue we noticed was some main cap fretting, (that Mark later fixed with longer precision fit alignment dowels, same two bolt main cap block).

I plan on doing something very similar on my aluminum head FACTORY 455 block (2 bolt main) using another T-Trim Vortech Supercharger at (9-10 lbs of boost) in my street convertible. Should be good for a easy 600 HP with a mild camshaft and factory crank. I would not worry about running 5300 rpm or 13 psi of boost but do not want to twist up the car (64 GTO) to brag about another 860+ HP engine. SO YES, NO PROBLEM IN MY MIND AT ALL.

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  #27  
Old 02-12-2021, 02:14 PM
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When working to turbocharge an engine platform designed in 1952-53 vs one designed in 1994-95, there better have been some improvements in the 45 year time span. The biggest improvement IMO, is in the stability of the block structure with the deep skirts and the 6 bolt main cap retention. Second would be the lifter valley area. The head deck is hardly better, still retaining a 10 bolt pattern. ( tiny bit of extra clamp load from the little inboard fasteners) If course the heads breath much better stock. But as the power level and boost really increase, an LS will turn into aluminum cole slaw just as easily as any other engine. I have seen plenty at the race track split in half and barely recognizable as a GM engine vs a Hemi or Ford. It's that "moderate" HP range where the LS really shines, cost wise vs a Pontiac. To make a Pontiac V-8 run reliably at 1000 HP, your going to have to spend some real money on it. With an LS, a trip to the junk yard and a moderate budget, and your there. It hurts me a little to write this, but it's what I see in my classes and at the drag strip. I personally wouldn't run one, but I understand why some people do. The TV shows all use them because they exist to sell parts for their sponsors. Not a lot of plug and play parts for a traditional Pontiac.

  #28  
Old 02-12-2021, 02:32 PM
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Tom, for my curiosity, was the Luhn engine installed in a vehicle? Stock(style, solid maybe) engine mounts, or an engine plate/mid plate? And was it launched hard on the strip? My personal opinion ( from reading on this forum about split production Pontiac blocks) is that while impressive, I don't think I could sink the money in a production block at 850+ horsepower and feel anywhere close to good about it. I know others have done it with success, at least for a time. And for a long time there wasn't an option. I feel like the OP shouldn't leave this discussion thinking it's anything more than a semi calculated risk to try that. And as has been noted, a trip to the junkyard will yield 1000 hp capable stuff with the corporate stuff. I believe if you go aftermarket block on the corporate stuff, you can get 6 head bolts per cylinder to go along with the cross bolted mains... It takes real dedication to stay with the Pontiac stuff, and I applaud those that have and do...

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  #29  
Old 02-12-2021, 04:52 PM
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Hi guys, it's been a while since I've posted on here. Life gets in the way of playing cars sometimes

So, I've got a 68 LeMans build on the back burner, and it's time to start getting the pieces together for it.

The idea is a street trim car with a couple turbos for fun. Automatic trans, in the 4L80 variety most likely.

I was starting to lean towards an LS, but I do have some parts on the shelf I'd rather use, if it's at all reasonable, so I was looking for some direction.

I've got a couple of 68 400 YC blocks and stock cranks. A set of 6X's and a set of 48's. I think the 48's might push the comp ratio a little too high?

From the reading I've done on this board, the stock stroke of the crank sounds like it would be ok up to a point?

The other parts I had in mind to source would be rods and pistons of the forged variety. The manifolds would likely be the airboat forward facing ones that I've seen here, and floating around the interwebs.

At the end of all that, I guess what I'm asking for is some advice based on the junk I have already laying around.

Sorry in advance for the long post



I like LS engines a lot. BUT they are getting to be like belly buttons and Ass&oles everybody’s got one.

Build a nice Pontiac for your. Pontiac people will go crazy over it

2 bolt block, cast crank, iron heads and 1000 hp how can you go wrong. Runs cool in traffic because compression is low .
Don’t need a over drive cause it’ll love a 3.08 gear and a glide they love to be lugged and not gear multiplied .

You’ll be happy as a clam with it and it’ll turn heads.

Again love LS motors but it ain’t exactly orginal .

I’m on 11 years w/o so much as a spark plug change.

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  #30  
Old 02-12-2021, 05:14 PM
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Quote:
Originally Posted by Scott65 View Post
Tom, for my curiosity, was the Luhn engine installed in a vehicle? Stock(style, solid maybe) engine mounts, or an engine plate/mid plate? And was it launched hard on the strip? My personal opinion ( from reading on this forum about split production Pontiac blocks) is that while impressive, I don't think I could sink the money in a production block at 850+ horsepower and feel anywhere close to good about it. I know others have done it with success, at least for a time. And for a long time there wasn't an option. I feel like the OP shouldn't leave this discussion thinking it's anything more than a semi calculated risk to try that. And as has been noted, a trip to the junkyard will yield 1000 hp capable stuff with the corporate stuff. I believe if you go aftermarket block on the corporate stuff, you can get 6 head bolts per cylinder to go along with the cross bolted mains... It takes real dedication to stay with the Pontiac stuff, and I applaud those that have and do...
When talking about the Pontiac block, and splitting them. One sure way to split a block is to use the 1955-1969 stock motor mount holes just above the oil pan mating surface. You can exacerbate the situation by using a solid mount on the left side. Using the early OEM mounts spreads the torque load over only 1 bulkhead (#3). The 1970-1979 mounts spread the load over 2 bulkheads (#2, and #3). If you anchor the left cylinder head you use all the bulkheads, plus the water crossover and intake manifold to the right bank.

Splitting blocks has a lot to do with how you choose to mount the engine in the chassis, not just because it's an 50 year old piece of iron. Pontiac changed the mounting system when they conceived the 455 long stroke engines. I believe the engineers knew that spreading the load over only 1 bulkhead wasn't going to work long term.


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  #31  
Old 02-12-2021, 09:42 PM
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Good stuff here, thanks guys.

I was just out at my machine guys shop, he's working on a different (much smaller) engine for me right now. I think I'm going to build up both engines. It makes sense to use the 6X's in a moderate low compression turbo build, and the #48's in a pump gas friendly N/A build.

I have a couple complete iron headed 5.3's kicking around in my friend group, and it would have been pretty easy to lay my hands on one of them, but I think it's worth the effort to keep a Pontiac in this one.

Besides, on the back, back burner is a 67 Lemans that could get something crazy in it.

  #32  
Old 02-15-2021, 09:32 AM
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I am getting a turbo kit for my daily with an LS3 and half of the hot side is a factory cast steel manifold with a custom made "log" manifold on the other-side of the engine. They're connected with a custom piece with a bellow joint for flex. With an S480 turbo, this kit is rated to 800hp. Yes, 800hp. Looking at these standard cast manifolds, they are very similar to Pontiac ones of the day. There is nothing stopping you from making a kit using standard Pontiac manifolds IMO and making similar power on similar boost (~14psi) with a similar turbo. If you've only got a 2bolt block, the block would be the weak point IMO if you were to CONSTANTLY abuse it. Pontiac cranks are not light! But keep it at about 700hp with studs and it should last a long time.

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  #33  
Old 02-15-2021, 10:46 AM
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what kit are you looking at

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Old 02-16-2021, 08:35 AM
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what kit are you looking at
A local Australian workshop called "Killerboost Manifolds". Darcy who owns it has spent LOTS of time and money developing the kit on his own car so it's not something that's been tacked together and told "it'll be fine". I think his personal car is making over 1000 at the tire with the next level kits. I'm only looking to run 12-14lbs at MOST because of the 6L80e gearbox and around 7lbs on the street because the car already is pretty silly and overpowered, so a turbo just adds to the stupidity and who doesn't need a turbo LS3 for your daily driver

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Old 02-16-2021, 08:59 AM
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I knocked up a turbo kit for my Pontiac about 25 years ago using reversed cast iron logs and J pipes, I tried it in draw through carb mode and blow through carb mode. It had 600hp capability but my lack of knowledge at the time on ignition timing and fuelling requirements for a 15 psi boosted engine curtailed the project due to detonation problems. No one else over here was using turbos on V8's and the internet (and PY) were unknown to me- so I ended up building a n/a 400 and ran 10's.

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  #36  
Old 05-12-2021, 04:19 PM
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So I was just in this situation myself, there's some reasons you'd do one vs the other so....

If you plan on selling the car, keeping it Pontiac will give you a better resale value.

If you're looking for 500 or less HP you can get some nice Ponty short block deals that don't really break the bank.

If you're looking to beat on the car, make power over 700 and don't wanna take out home loans from engine failures, then CHEVY. It's not even close.

You can buy the LS3 6.2L create from Summit at $7800, then the Hooker turbo headers around $700 and a turbo for $1400. You'll need a DP and other parts but you're around $12k after a tune on your LS computer.

https://www.summitracing.com/parts/nal-19419862

I just got the run around on my Ponty engine and lets say I'm $16k into just the engine aspect and I'm using the stock block. It's a real crapfest out there for 600+ NA horsepower on a 400 Pontiac. I would've gone IA2 if I could've foreseen what just happened to me over the last 9 months but even that's $18k.

I like Mark Luhn, but the superchargers are from $8k up, you can get the full LS3 engine with sensors for less.

It really comes down to your short and long term car goals. I'm keeping mine forever and can afford this so I stayed Pontiac and built the hell out of the 400. I wanted at least 600hp/625tq and am on E40 to run 11.7 comp and make nice power NA to limit forced air issues.

So much to consider, take your time.

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  #37  
Old 05-19-2021, 05:37 PM
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Originally Posted by 455dan View Post
I must have something wrong with me .

example "Overhaulin"

They open the hood on any Pontiac, Buick or Old's and a gleaming LS SBC between the frame rails.
Literally get a sinking feeling, feel ill.... especially any car that actually had a 400,401, 425, 428, 430 or 455 IN the car when they "took" it.

I should seek professional help,

Accepted Ponchos cost more to build than SBC.

I don't hate SBC's had a 9C1 police Caprice with LT1 and put 90000 on top of the 110 K it had when I got it. It was a Great running hiway cruiser. Never owned a new LS but am sure they run even better.
Will be watching with interest what the OP decides to do, and wish him a successful build of a 600+ HP power plant, regardless of what he choses, but I hope he chooses the Pontiac build.

I get a kick out of people who get bent out of shape over the LS in my 71.

I just laugh and tell them they're right, its awful. They dont seem to get the sarcasm.

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  #38  
Old 05-19-2021, 05:46 PM
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You can make 1600HP with a junk yard LS by opening the ring gap.Sounds too EZ to me!Tom

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Old 05-19-2021, 06:03 PM
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Chevy in a Pontiac.............LOL!
Junk!



GTO George

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Old 05-19-2021, 07:34 PM
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I own an LS2 05 GTO street car since new, It's a great engine, it's not a chevy engine, but a combination of every divisional engine best ideas. That is the first point that many have wrong.

The LS engines are a true corporate engine same as dodge, plymouth and chrysler used to have separate divisional engines. Ford, lincoln, and mercury used to have divisional engines, but both companies came under one corporate design decades ago. GM held out with separate divisional engine much longer than either of their competitors

I have always used Pontiac Stratostreak engines in all my race cars, even though sbc engines are cheaper to build, and they were legal I always chose the Pontiac Stratostreak as powerplant for all my race cars.

Big Chief still runs a boosted Pontiac Stratostreak with E heads and regularly takes down many of his competitors on the street Outlaw shows. I guess if you need more than 3000 HP you should be looking at Proline specialized race engines. Many of the chevy bodied cars on Street Outlaws run hemi engines, not SBC, BBC, or LS engines, so no matter what you have under your hood, there's something better out there.

My own personal preference is if a Pontiac came with a Stratostreak engine, you'll garner more appreciation from the average car guy that actually knows something about vintage musclecars, rather than become one of the "me too" people that put a SBC, or an LS engine in everything with 4 wheels on it. Yes it's cheaper, and probably easier to pull power out of one of them, but the self satisfaction of shutting someone up that brags up there SBC, BBC, hemi, or LS powered hot rod by dusting them with a Pontiac, as the commercial says, "PRICELESS"!!!

When Mike and Eric were running the Boss Bird Nitro Funny car they were beating hemi powered cars regularly when they ran in nostalgia events, and match races. That is satisfaction when they were told numerous times they'd never be successful with a Stratostreak Pontiac nitro engine between the frame rails of their car.

It all comes down to fortitude, some people follow their dreams to the end, while others compromise their dreams, and do what is easiest.

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