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Hey Y'all

Im putting together a twin turbocharged 454 build for my 1970 skylark. Now, obviously I'm super excited for this project, as my current 350 has only around 200 horsepower at the wheels TOPS (some idiot threw in a chevy 350 that was actually WEAKER than the stock Buick 350. go figure) and I'm thinking that since I have a chevy motor already, I might as well throw in a stronger chevy to give her some real grunt.

my problem is hood clearance. my current 350 is already almost touching the top of hood, maybe half an inch from the top. the intake is just a basic sp2p edelbrock intake with a 1/2 inch to 3/4 inch carb spacer and it has an inch and a half tall air cleaner.

I've heard that the 454 is about an inch or two taller than a 350 from top to bottom. I love the look of my hood so much. spent hours designing the stripes and placing the hood tach in the best spot possible so it doesn't disturb the lines on the hood. I would hate to have to add a hood cowl or get a brand new hood just because my engine is a teensy bit taller. Going naturally aspirated wouldn't have been a problem, but adding a turbo plenum on top might be too much.

I know I could just not add the carb spacer, but I also wanted to add a nitrous plate to deal with turbo lag, which is roughly the same height.

Here are some solutions that I have thought of, but also have questions about:

I could try and avoid some air gap intakes when I build it. the problem is, this will sacrafice some power, and I was really thinking of making the Edelbrock RPM Performer Air Gap part of my build.

I could buy lower engine mounts. This was recommended to me by a friend who has never built a motor in his life, but then again, neither have I. I'd never even heard of that.

I could buy a low profile plenum for the turbo air pipes. not sure how that will affect air flow though.

So yeah, I'm kind of stuck. I could really use some help here from you experience fellers! Thanks in advance:D
 

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There are a couple questions that need to be asked before you spend a cent.


What is the intended use?


What realistic power are you after?
What fuel are you intending to run?
What transmission, rear axle, rear axle ratios?
Have you ever changed carb jets?
Have you ever ran nitrous before?
Have you ever built a short block?
Have you ever modified manifolds or headers?
Any previously modified turbo builds?
Do you have experence tuning fuel injection?


What is your realistic budget for the engine, transmission, rear axle, and everything else that moves?
 

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Discussion Starter #3
There are a couple questions that need to be asked before you spend a cent.


What is the intended use?


What realistic power are you after?
What fuel are you intending to run?
What transmission, rear axle, rear axle ratios?
Have you ever changed carb jets?
Have you ever ran nitrous before?
Have you ever built a short block?
Have you ever modified manifolds or headers?
Any previously modified turbo builds?
Do you have experence tuning fuel injection?


What is your realistic budget for the engine, transmission, rear axle, and everything else that moves?
Thank you, but I don't really need help with the actual engine build, as I got a friend helping me with that, I'm just trying to find a way to keep my stock hood
 

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I would address this problem the same way that I address every problem that comes up......jump in with both feet.

Since you can't go taller, you'll have to go lower. This means sawing the front crossmember out of the car and going back in with a drag race front crossmember at the front of the motor, so that the motor can be lower in the car than it is stock. You'll also probably need to do the same thing with the transmission crossmember, to drop the whole engine and transmission lower in the car. You may be able to use the stock crossmember that you cut out and just fit it into the car lower than it was stock. This operation is going to require some out of the ordinary skills to pull off, so I hope you are up to it. You'll need to begin with an absolutely flat and level concrete floor......this does not mean a residential garage floor, they aren't even close to being flat and level.

The trick to this whole operation will be ending up with the attitude of the body sitting at an attractive stance, whether that means perfectly level or with a little rake.

Let me help you out a little by giving you the instructions that I wrote several years ago for installing a front clip. That would be basically what you would be doing, changing out the front clip......just read through it and get a feel for what you need to do......
https://www.crankshaftcoalition.com/wiki/Frame_swaps

You know, now that I've thought about this for a few minutes, there is no way under the Sun that i would cut the crossmember out of a car just to save the hood. The hood would just have to get real chummy with my Sawzall.......Sorry pal......:eek:
 

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turbo cars don't need cubic inches---my good friend races 2JZ Toyotas in various cars, makes 1800-2500 HP from 180 cubic inches. His daily driven Supra makes 750 HP on pump 93, 1100 on race gas.

Build a small block, boost it 35 psi, keep the hood
 

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turbo cars don't need cubic inches---my good friend races 2JZ Toyotas in various cars, makes 1800-2500 HP from 180 cubic inches. His daily driven Supra makes 750 HP on pump 93, 1100 on race gas.

Build a small block, boost it 35 psi, keep the hood
There used to be a guy who came out to Firebird International Raceway, where I teched, every Friday night. He drove in off the street in his Toyota Supra, changed rear tires and blasted off mid-7 second passes in the quarter mile all night long. The car had the original inline 6 cylinder motor in it with a ton of turbo and coolers. I don't remember the trap speeds, but at mid 7's, it must have been around 175 mph.
 

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turbo cars don't need cubic inches---my good friend races 2JZ Toyotas in various cars, makes 1800-2500 HP from 180 cubic inches. His daily driven Supra makes 750 HP on pump 93, 1100 on race gas.

Build a small block, boost it 35 psi, keep the hood
There used to be a guy who came out to Firebird International Raceway, where I teched, every Friday night. He drove in off the street in his Toyota Supra, changed rear tires and blasted off mid-7 second passes in the quarter mile all night long. The car had the original inline 6 cylinder motor in it with a ton of turbo and coolers. I don't remember the trap speeds, but at mid 7's, it must have been around 175 mph.
I was going to lean towards a 3800 to keep things "Buick", or run a LS with 2wd 4l80 depending on the power level.
But I love a OHC(DOHC) setup especially if your running boost. There are several 4 cylinder engines that have overbuilt factory bottom ends.

All of these have fuel injection in common. The best parts in the world will just be a pile of parts if you don't tune them for the setting.
Fuel injection can make tuning changes in milliseconds which means you can run closer to the edge and make more power.

You can run a blow through carb on top of a big block. But you need to be "safe" factoring for all the temperature, atmosphere, fuel, etc. Which requires tuning or having a tune that covers all the ranges of conditions.

Now if you want a daily driver/weekend warrior making 450hp/550lbs that is a diffrent engine then a 600+ engine that is moved track to track inside a trailer.

Then we get to transmission. A 2 speed or a 3 speed with a direct final is going to require a diffrent engine then something with overdrive. This looks at your engine rpm range. 600hp is nice. But if that is made at 6500rpm and you shift at 3000 90% of the time your going to be shifting at 350 ish hp.

We "fix" this with more gear in the rear. So now your running 4.xx gearing and MATCH this with a diffrent converter. Of course we have a top speed limitation fpr the comfortable cruising rpm.

Anything can go 100 mph given enough time. There are very few cars that can't be built to have a 5 second 0-60 or a 11 second quarter with piles of cash and knowledge thrown at them.

There will always be something faster, or better at a aspect then your ride.

You need to be build for YOUR application.

If you want advise we need to know what your after. If you want cut up the frame for something to fit and be lighter then that CAN work. If you want to leave the frame and body alone and run NA or a smaller engine that CAN work. If you want to daily drive 600hp on e85 that CAN work.

But it only works if it fits your application.

You would not run slicks at a rally race. The build needs to fit the application.
 

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I am a body technician at a classic and custom shop, nothing to do with powertrain. Here are my raw thoughts:

Crossmember sag is common on that platform.

The SBC in your Skylark may not be mounted in the same position as it would be in a Malibu due to a less-than-whole-hearted engine swap. Meaning the combination of frame brackets and engine mounts used may not provide the as-designed engine mounting height for original SBC powered A-body cars. If you can slip fingers between crossmember and oil pan but not air cleaner and hood, thats a sign that your existing reference is no good.

Anything you use is going to have a hat or plenum box and there are low profile versions of both. I don't see the problem. If all you end up with is an inch and a half of height available, OK... build a plenum if you can't find one prefabricated. But there should be room.

About bending of air... twin turbo nitrous ( opinion paragraph withheld ) numbers into a muscle era car with sticky tires obviously presents compromises. Lots of neat high dollar builds out there with ridiculously restrictive air intakes, man. Yeah, heres the sheet it went 800 on the builder's dyno lets stick it under our stock hood hee hee. Sewer pipe exhaust, soda straw intake and its really 750 now. :rolleyes: Who cares? Tune in car with restriction and still play hell getting 650 to the asphalt. And enjoy.

1970-2 Monte Carlo mounted the engine mounted slightly lower and farther back than Chevelle, facilitated by extra wheelbase. Perhaps study differences and consider the firewall to be the potentially sacrificial area rather than the hood.

Hood inner structure can be modified. Crossmembers can be clearanced. Oil pans can be fabbed. Engine position is where you put it with an angle finder and all your parts.

Really what you have is very common trouble, speculating a build together. Veeery risky business there. Get everything you intend to use. Take off everything you do not. Do this in an adequately equipped facility with the car sufficiently disassembled, clean, and thoroughly inspected ( those frames have known cracking trouble spots. I actually stuck a pencil through the crusty frame on a car like yours that looked great and dealers welded lots of control arm mounts back on ) because I have had trouble with a couple myself.

You really, seriously have to go to the car with the stuff and make it happen. Five minutes in, you'll know more than after five hours' research. I am confident that altough it was never me that did it, that is a package that has been done more than once already and heres the important thing to remember...

If it fits in a Chevelle, it will fit in a Skylark.
 

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Twin turbo nitrous 454 sounds like about 3500-4000 HP... are you building an engine and drive train and rear end and suspension to handle all that? Or going more for looks and reduced power?
 
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