# Engine Decisions...



## Indecision (Oct 24, 2010)

I'm more thinking out loud here than anything... just wanting to bounce some ideas off you guys.

I have a 66 GTO that currently has a 428 with a spun bearing somewhere and a muncie 4spd. Not sure on rear gearing. In 4th at like 60mph i'm spinning 3000rpm or so, so she never really saw much above that in cruise. 

My initial goal when I bought the car was to do an LS/T56 swap, which I know 90% of the people hear hate the idea of. But I wanted to make decent power (500+whp) and daily drive the car. You can't really argue with the reliability and potential of the modern LS motor. Long term I wanted an LS3 or possible even an L7, but I'd start with an LS1 until I could afford the bigger engine.

NOW... i'm looking at doing one of the 455 long blocks from 455 Long Block

I'd have them do some aluminum Edelbrock heads (I'm limited to 91 octane in AZ), and most likely long tubes, performer RPM intake, and a proform 750CFM carb (at first glance, i'd talk to some people first.) The problem I'm having is that I'd almost have as much in to it at the LS swap, but I'd still just get <10MPG. An LS3 with bolts ons could do a lot better, especially if I went turbo. LS7 would be a bit better, but not much. 

He says I'd be safe at 10:1 because of the aluminum heads, and I'd do a mid range cam at some point. The car would probably make 600hp at the crank, and I'd be happy with that. Especially once I can put in 93 and advance the timing a bit more. 

If I went that route, I'd be eventually looking in to at least putting my T56 in there. I could run 4.10s, have amazing acceleration and 1800rpm at 75mph. 

I'm looking at like a $10k inititial investment either way and I'm conflicted on which way to go... Pontiac would have more power at installation, and more cool factor. LS1 would much better reliability, easier starts, have way better gas mileage, decent power and the t56 at installation.

Any thoughts on either of the 2 options?


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## BearGFR (Aug 25, 2008)

I'd say you're pretty well covered the ground there.  Pick whichever one YOU like the best and run with it.

Bear


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## judge71 (May 26, 2015)

Like you my "correct" engine is long gone and the driveability of an LS is really attractive.Either way your driving a GTO..you can't make a wrong choice here.


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## Pinion head (Jan 3, 2015)

Indecision said:


> I'm more thinking out loud here than anything... just wanting to bounce some ideas off you guys.
> 
> I have a 66 GTO that currently has a 428 with a spun bearing somewhere and a muncie 4spd. Not sure on rear gearing. In 4th at like 60mph i'm spinning 3000rpm or so, so she never really saw much above that in cruise.
> 
> ...


A few thoughts...just thinking out loud, as you mention above.

600 HP at the crank (and even higher level of torque) from a streetable naturally aspirated 400 based 455 stroker with 87cc eheads, with a "mid range cam"... not going to happen. 

The above linked 455 block option with unported 87cc E heads, a RAIV cam and Rhodes lifters (the cam and lifters offered in the above pkg), made 440 gross HP and near 500 ft lbs of torque through a set of Doug's headers with a performer rpm and an 850 Holley.. Port the 87 cc e-heads considerably and go with a larger cam, you might get another 100 hp, but at a higher rpm peak... much better 455 stroker street$/strip combo's out there. 

Transmission choice.. A pullout T56 won't hold up, if the plan is to use that 600/600+ torque. Different story if it's in a putt around vehicle w that amt of torque.

Further back in the drivetrain, the '66 gray iron 8.2 Pontiac rear can be coaxed to regularly hold up to 500 ft lbs of torque (with minimal track use ) but only after about $1600 worth of upgrades... IMHO, that $1600 can go a long way to building a much stronger rear, one that actually has pinion support in the housing and is not bandaided with an LPW style rear cover to attemp to keep things from moving around. Gray iron 8.2 10 bolts, just not a good platform to throw loads of torque at, they went out of fashion behind all late 60's performance GM products at about the 450 ft/ lbs torque level.


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## oldskool (Apr 26, 2015)

"...Any thoughts on either of the 2 options?"


Yeah, on these forums, we all have our opinions and thoughts. So, I'll add mine.

On the non Pontiac engine option. It is my own personal opinion that to put anything other than a Pontiac engine in any '60's to mid '70's Pontiacs, especially Goats and Birds, is an absolute insult to old school Pontiac freaks everywhere. 

Some say "It's yours, do what you want with it." But I say, if you want a Chevy engine, buy a Chevy body, or a later Pontiac that came with a Chevy engine. And at my age, I make no apologies for holding this opinion. Actually, my age has nothing to do with it. I've felt this way for a LONG time. Very few things have ever disappointed me as much as walking up to a nice lookin Bird or Goat, at the track, and seeing a Chevy engine in it. I would usually not even talk to the guy about it. Was not interested in the car at all, after seeing the Chevy engine. 

Now, about the Pontiac engine. Why do you think you need (or why do you want) 600hp, in a street driven car ?

Yes, with the technology and parts available today it is easily possible, especially with the aftermarket blocks. A properly built 535 can meet your power goals. But I just can't imagine needing that kind of power in a street car. 

The 455 you linked can be built with 9:1 comp or even a bit less, to work with your 91 pump gas. It will have about 400hp, 500ft lbs of torque, and will melt hard rubber street tires. I've got a very similar engine in a '68 Bird Bracket car. We are expecting it to run high 11's easily, maybe even quicker.

The torque of these engines will break lots of parts. I learned that the hard way.  So, I can only imagine what a 600hp monster can break. 

Yeah, they make HD parts that can take the pressure. But they cost mega bucks. You mentioned gas mileage. If you build less motor, you'll have enuff extra money to keep you supplied in gas for a long time.

If you have E-85 in your area, there's one way around your 91 octane gas problem. It won't cost any more than pump gas, runs cooler, and has more octane, so that you can run more compression. Lots of guys are using it on the street and strip. I just Googled E-85 in Chino Valley, AZ. It showed they sell it at a Pacific Pride station. Don't know how current that info is.

http://www.e85locator.net/State Pages/ArizonaE85stationlocations.html#ChinoValley

But hey, if you can come up with the coins, there are several Pontiac engine builders who can supply you with a streetable Pontiac engine in the 500-600hp range.

Kauffman Racing Equipment

Butler Performance - 474 C.I. 660 HP Stroker Pontiac Engines

Tin Indian Performance | Specializing in High Performance Pontiac Parts and Pontiac Engine Building

pontiac crate engines

I'd go with the Len Williams 455 or 400 block 4.25 stroker, with forged rods, and have him shave the 6x heads just enuff to get no more than 9:1 CR. Then put it in your car and just see if you think you need more power. You may be surprised at how 500ft lbs of torque feels, especially with a 5 or 6-speed tranny.

Then, if you need more speed, you can add different parts later. Hey, it's all just food for thought.


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## Indecision (Oct 24, 2010)

BearGFR said:


> I'd say you're pretty well covered the ground there.  Pick whichever one YOU like the best and run with it.
> 
> Bear


If I bought whatever I liked best, I'd have 3 66 GTOs in my garage... LS7 pro touring setup, HUGE cube poncho making 1000+whp, and a stock 66 Tripower, lol. I have to make decisions unfortunately. 



judge71 said:


> Like you my "correct" engine is long gone and the driveability of an LS is really attractive.Either way your driving a GTO..you can't make a wrong choice here.


No argument there...



Pinion head said:


> A few thoughts...just thinking out loud, as you mention above.
> 
> 600 HP at the crank (and even higher level of torque) from a streetable naturally aspirated 400 based 455 stroker with 87cc eheads, with a "mid range cam"... not going to happen.
> 
> ...


You really don't think an actual 455 with 10:1 compression, edelbrock heads, long tubes, performer rpm, mid range or possibly larger cam (I haven't looked at all the options yet) and appropriate carb would make at least over 500whp?

I don't have a pullout T56... I have an RPM Stage VI T56 with Solid keys, Bronze fork pads, Bronze shifter bushing, Steel 3-4 shifter fork, modified 1-2 shifter fork, Hand fit sliders and hubs, Compressed Carbon blocking rings, Performance Metal Micropolish, and Cryogenic Processing. Held up on my last 600ftlb car without any issues, but it was also substantially lighter. 

I'm aware the rear end is a weak point, but that would be a little farther down the line. I'd be gentle with her until I could put a 9" in it. Maybe i'll back half it at some point, I don't know, I'm not a doctor. 



oldskool said:


> "...Any thoughts on either of the 2 options?"
> 
> 
> Yeah, on these forums, we all have our opinions and thoughts. So, I'll add mine.
> ...


I understand the mentality of the non-pontiac thing, as addressed in the original post. But at least the LS1 and LS2 came in a Pontiac badged car, and at that generation I'd say it's more accurate to call them "GM engines" rather than "Chevy engines." Either way the LS is an inarguably awesome platform, and it wouldn't be a bad road to go down.

Keeping it Poncho sounds fun too, though. 

I "need/want" north of 500whp in a street driven car for the same reason I drive a 66 GTO to begin with and not a new Civic. It's way more *&%[email protected]^!*&%[email protected]^!*&%[email protected]^!*&%[email protected]^!ing fun. 

My last car made 400hp NA with a 200 shot of nitrous, and went high tens just because it was set up for road racing (without the bottle obviously.) So it didn't hook, even on 27x10 ET Street bias plys. With 500hp to the wheels, the GTO will still be slower unless I put an autotragic in it, more power, and and some fat tires just because of the weight disparity. 

Even if there is E85 at that one location, it's not spread out through the area. I want to be able to go on a cruise or something, and not be paranoid about finding one of the few stations in the state that have E85. 

And you recommend the forged Les Williams without the heads and whatnot? Why? According to them I'd still be able to run 91 and 10:1 because of the more efficient cooling of the aluminum heads. I'm not hugely familiar with Pontiac engines, and there isn't a whole lot of places to read up on them simply due to how uncommon they are. Also as stated, I plan to run slightly retarded timing as well, so once I move back to the land of E85/93octane I can crank it up and get a few more hp out of it. 

I may also look in to fuel injection eventually, but that's a road I'll cross when I get farther down the line.

I also would love to have someplace like Butler build me an engine, but they wanted like $6k just to rebuild my 428 to stock spec, that didn't include a reduction in compression or anything to my knowledge, so unfortunately they aren't a valid option at this point. If I keep it a Pontiac, it will be a 455.


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## oldskool (Apr 26, 2015)

Hey, looks like you have all your bases covered, and know a lot more about cars than I do.

So good luck with it. Hope you enjoy it, whichever way you decide to go.


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## Indecision (Oct 24, 2010)

Far from it... I know what I want, I'm just not sure how to get there. Like I said pontiacs aren't exactly common engines and there isn't a lot of reading up on them you can do. 

I'm very familiar with the LS and what a lot of combos are good for, but the Pontiac is foreign to me (another reason I was leaning LS.)

I thought the higher compression, aluminum edelbrock heads, cam, and performer rpm intake (or torker II if I have the clearance) would get me there but it doesn't appear that way now. And that was high on the budget for me. So I don't have much more I can go past that. 

If I go the poncho route, I'd like to see 500whp on a stock bore/stroke 455 and 93 octane (knowing I'd have to retard the timing a bit to avoid knocking on 91 until I move.) It would have to be reasonably reliable and I don't want to have to lose another limb to afford it. 

If it comes down to it, the les Williams 455 with a 100 shot will get it close enough... Or do these engines hate nitrous and I'm unaware?


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## PontiacJim (Dec 29, 2012)

Reading through many of your older posts, you seemed to have already covered this, no? You had made up your mind on an LS engine because of the T-56 you were going to use from your Mazda. If the T-56 is from your Mazda, then where is the LS that was in it?

The '66 GTO had the 428/4-speed & 4.11's and it was rebuilt a year previous to your ownership and it spun a bearing. It was suggested to keep the 428 and rebuild it, but it was going to cost more than your allotted budget at the time. So, you were then going to look for a 400 short block as it was more in your budget.

Now, as I read this post, you are considering a 455 while still gnawing at the LS engine. So you have not as of yet diagnosed the 428 spun bearing, it seems you are not interested in using it as your base engine, then contemplated a 400 because of your budget limit, and now you are throwing out your choice of a 455 with 600HP while still being nagged by the LS engine.:willy:

You had the Mazda with the LS/T-56 and know what it was capable of. You had the 428/4-speed and know what that engine was capable of. Pontiac or Chevy, its your car/your choice. 

Any carburetored Pontiac pushing 600 HP is not cheap, so go LS. No 600 HP Pontiac will even come close to the miles-per-gallon you will get from an LS, so go LS. A 600HP Pontiac will not have the longevity of an LS, so go LS. A Pontiac will not RPM on a regular basis as done on a road racer like an LS(as they will spin bearings), so go LS. The T-56 will be an easier bolt-up to an LS, so go LS.

That all said, I've made up my mind for you even though I am a "Pontiac" engine guy. Go with the LS so you will be happy.:bannana::thumbsup:


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## Indecision (Oct 24, 2010)

It's been talked about before when I was trying to rebuild the 428 and had like $2500 to spend and now I can swing about 4x that. 

I pulled the trans and clutch from the car because no one buys an FC LS1 RX7 for premium parts, they want it cheap. So I pulled the T56 and clutch, put a stock trans and a cheaper clutch in and sold it for exactly what I would've got for it before with $3500 less in parts. 

Rebuilding the 428 is always an option, I just feel like if I'm going to spend $4500 to have it rebuilt right (someone sent me a link to a good place I can't remember off the top of my head.) I could just buy a 455 outright from Les Williams and do whatever with the 428 down the road. 

I do have some more money to spend now than I did then, so options are different. I have about $10k to throw at it right now. That's about what I'd be at with the LS swap or at least in the ballpark. The Les Williams 455 is half that, but I figure if I can do a little more at the same time that would be great, and I want to do an aluminum radiator and electric fans regardless. 500whp is really my goal if I got the Pontiac route, I just thought the 455 would be capable of a bit more than that fairly easily. 

Mileage is a concern, I'm not going to lie. But I have a daily driver for a reason, and if I I have to drive that most days and roll the GTO out on weekends or whatever, that's not the end of the world. 

The problem I have is both options are good in their own right, and while I love the LS option, my inner keep-it-a-pontiac voice is keeping me from pulling the trigger. 

I wouldn't road race the GTO, it would be a street/strip setup and would only see high revs occasionally. Realistically I'd mostly just cruise around in it for the time being. The drag strip is a 2hr drive in Phoenix and I wouldn't make the trip more than once a month most likely. I really 500whp would keep me happy until I could afford to do something bigger. If I go to the pontiac route, it will likely become more of a weekend drag car over time than pro-touring style daily driver. 

So I guess the more accurate questions is what would I need to do to make 500whp (or at least close to that) in a poncho?


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## PontiacJim (Dec 29, 2012)

If I wanted to go something a little different, and still get big HP. I would skip a true 455 only because starting with a 455 can cost as they are harder to find.

Next option and probably best buy, is to go with a 400 block and the Butler Stroker kit (rotating assembly) to get you 461 or so cubic inches. Cubic inches is where you get your torque and power. Butler offers a complete shortblock for $3,500 as well. Butler Performance - Pontiac Short Block Kits You could probably go cheaper if you could find a 400 locally and just go with the rotating kit and have your local machine shop put it together for you.

Next, I would consider a basic set of 6X iron Pontiac heads set-up with good parts/pieces, 3 angle valve job, and port matching. No fancy porting or polishing needed, just get your compression to where you can use a turbo.

Then I would get a turbo charger and fit it to your engine. Here is some info on it S400 Build - PONTIAC ZONE TECH FORUMS 

This should get you well into the HP range you want, be reasonable on gas, and I would think come in under your budget if you are looking to be in the 10K range. Put it all down on paper and see what you come up with for a cost.:thumbsup:


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## ALKYGTO (Mar 29, 2010)

I like Jims suggestion. Build a stout low compression motor with forced induction in mind and add that later after you've put a few miles on the car.

Roots blowers are great for tremendous gains in low end power (instant ON! :eek2 blowers are available in roots or centrifugal (think belt driven turbo) and are simple, durable and generally cheaper than a turbo (but not inexpensive).

Turbos make great power for "free" not sapping additional power from the crank and instead using exhaust gasses to drive the "supercharger".....easier on the engine "if" all the appropriate safeguards are utilized...which drives up cost and complexity.

Is E85 available in your area?


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## Indecision (Oct 24, 2010)

Turbos are cool and all, but the power curve on an N/A, nitrous, or positive displacement supercharged engine is so much better... I'd rather do a roots or better yet a twin screw blower. It's unlikely I'd go centrifugal, but guys are making good power with the F1 (granted on other platforms.) Again though, the power curve is less favorable. 

Not to mention, nothing sounds cooler than a monster cam V8, and you lose that with FI.

Also, what's "low compression" on these cars... normally I'd say 9:1, but we need that just to run pump gas...

If I went LS, I could see a Kenne Bell or TVS in my future (or even the stock blower off an LSA,) but then the mileage is almost the same as the Pontiac anyway, which is one of the reasons I'm leaning back towards the poncho. My best friend has an 11 CTS-V and is making like 600whp with intake, exhaust, heat exchanger, pulley(s?), E85 and a tune and that car is a blast. 

I do not have E85 here, or at least it's not wide spread enough. But there's a solid chance I'll be moving back to Indianapolis in the next 2 years and E85 is plentiful there. 

I kind of mentioned it before, but with the Pontiacs, is there a downside to say getting that forged Len Williams 455 (without the aforementioned heads) and just putting a 100 or a 150 shot on it? I'd have to fill bottles in phoenix, but used bottles are fairly cheap, and I could fill like 5 at a time... I've had 3 bottle fed cars and see no issue in doing it again. 

That also gives me a block to do a serious build on a few years down the road if I desire.


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## ml3126 (Jun 27, 2011)

I did a 2002 ls6 swap in a 1989 iroc. It was fun at first but my current 70 GTO with 455, SD ported iron heads and a Cliff Ruggles set up Quadrajet is way better imo.


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## Smitrock67 (Apr 4, 2021)

Indecision said:


> I'm more thinking out loud here than anything... just wanting to bounce some ideas off you guys.
> 
> I have a 66 GTO that currently has a 428 with a spun bearing somewhere and a muncie 4spd. Not sure on rear gearing. In 4th at like 60mph i'm spinning 3000rpm or so, so she never really saw much above that in cruise.
> 
> ...


If you are a purist go with the 455 option but if not I would go the LS route for obvious reasons. More reliable, parts readily available at any auto store, dealers or service shops can work on it due to the diagnostic port, power levels and better mpg.


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