Firebird project

[OC]

I’m planning the build up of a 1987-ish Pontiac Firebird. Its been a long time since I owned a fast car, so this one will help make up for lost time. (I’ve owned a 1995 Geo Metro since Aug 95, and I’ve had enough of the 40mpg world. I’d like to be able to get out of my own way once in a while.) To that end, I’ve been researching different buildups of small block Chevys. I found several good ones. I’m using those for reference, so I’ll list the articles if anyone's interested:

Car Craft Jul-01 450hp 350
Car Craft Sep-01 Edelbrock Etec heads
Car Craft Aug-01 Build an Awsome Daily Driver
Hot Rod Sep-01 Real World Peformance
Hot Rod Aug-01 500hp 427 small block
GM High-Tech Performance Sep-01 396 TPI buildup

Also, there have been two issues from Hot Rod that had articles titled 12 seconds and 20mpg. I also have an issue from December 1988 that featured a Lingenfelter tweaked 86 Vette. The TPI setup was replace with stock-looking but better-flowing parts, the 350 was stroked to 383, and the 700R4 had a Gear Vendors auxiliary overdrive attached. This gave an overdrive ratio of .546:1, with a final drive ratio of 1.93:1 with a 3.55 ring & pinion. This car made 368 hp and 451 lbs/ft of torque. It did the ¼ mile in 12.53@111mph. It also achieved steady-state fuel economy in the 30s. Even including several top-speed runs, it still got 18.9 mpg. Amazing. I have this article scanned, so email me if you'd like to see it.

I also draw outside the box, so I’m not going to duplicate this effort. Instead I’ll go with a 390 (4” bore, 3.875 stroke) using a beefy new block and rotating assembly from from Bill Mitchell, Edelbrock E-Tec 170 heads, TPI intake parts from TPIS, and a roller cam do be decided after more research. I'm shooting for about 430hp. I'll use the same tranny setup that Lingenfelter used – a TH700R4 with a Gear Vendors overdrive. For the rear end, a 9 inch from Currie Enterprises with an Auburn limited slip diff and 3.00 gears. With 275/40ZR-17 tires (probably Kumhos), this should get me 1755rpm at 60 mph. Getting out of the GV od, this’ll place me at about 2200rpm, right where the torque curve should start to get fat. Hopefully I can get started on this project by the end of the year.

-OC

[OC]

NOTE: This post is taken from another thread that got off-topic, so I'm consolidating that info and adding it here.
***

Ok - revised plan. Understand that my premise here is "too much is just enough".

A 415 small block Chevy with a Bill Bitchell block, Scat crank, Edelbrock E-Tec heads, MiniRam III from TPIS using SDS EFI, and 4L80E tranny. Numbers show 391hp and 451tq. This is Stage One.

Stage Two calls for a single intercooled turbo with 10-ish lbs of boost. That should take it to about 657hp and 757tq. That's why the 4L80E and not the 4L60 - the 4L60 would be torn to pieces.

CarTest shows 0-60 in 3.2 seconds, and the 1/4 mile in 11.5 @ 130.4.

Those acceleration numbers assume a 7000 rpm redline and a 2.8:1 rear end - with these I can actually hit 60mph in 1st gear. Also, this is running a turbo, so there's no boost umntil about 15mph or so from a full stop. This significantly helps the 0-60 time. When the shift into 2nd occurs, the engine rpms drop back down into a range where more torque is being made, and the tires go up in smoke - hence the extra time for the 1/4 mile.

This is a street vehicle, not a race car, so no slicks for me. Slicks would of course help harness much more power on the 1-2 shift, which would help the 1/4 mile time.

And yes, those power number are at the crank, not the rear wheels. Still, the acceleration numbers hold.

-OC

[johnnymk]

I am a real sucker for the 327-350 HP engine. A lot of young people probably aren't that familiar with this engine. It was only available from about 1965 to 1968. I had one in a Corvette that I presently own. I over revved it and put a rod through the block. But it was a screamer!! I had an Edelbrock Torker manifold, 780 Holley, electronic ignition and headers with a 3.36 rear. I never took it to the track, but I blew off a lot of cars street racing. The last race I remember where a guy beat me by a 1/2 car length was a 455 equipped 65 GTO.
The point is I believe in the oversquare theory relevant to the bore and stroke for drag racing. A few people that have been around also agree with the theory that the bore should always be larger than the stroke. The 327 had this combination.
Don Garlits recently stated that he believed that the 327-350 HP engine was the best engine available from the car industry.I didn't read it, but a friend of mine heard him quote it.
Point? If you want to occasionally go street racing, find this engine and modify it slightly. Add fuel injection from a junk police car and tweak it. I would imagine for a minimal investment, you could easily crank out 425=450 HP, maybe even 475 HP.
I have a 57 Chevy that I plan on building this combination one of these days. I expect to use a modified 700R4 behind it so that I can get decent fuel economy.Since most OD automatics are .7 or .8 in 5th, a 2.8 rear axle would be equivalent to a 4.0 if it were only a 4 speed. I remember that 4.11's were the rage when I used to street race. 4.56 made the engines whine too much and the fuel mileage was awful.

[Realrammstein]

Man, you guys are getting me all nostalgic about my last car(87 TA GTA). I have nowhere near the knowledge of building it up, but with just exhaust she was putting down last Gen Cobras. Wish I hadn't sold it....

[natem02]

A 327 in a 3rd Gen Firebird would be very unusual and therefor pretty cool. But if you really want to go for an oddball. Build a 302(3" stroke x 4" bore). Chevy produced these back in the late 60s to make the Camaro legal for Trans Am racing and they were amazing little engines. They'd pull all the way up through 7000 rpm. They were rated at just under 300hp if I remember, but in reality they cranked out over 350hp and building one to produce around 400hp would be fairly easy. One last thing about your choice of a turbo, it would be a lot easier if you went with a P-1SC intercooled supercharger kit from Procharger(http://www.procharger.com. They're much easier to setup than a turbo and produce power just as well, minus the lag and oiling problems. They're also a bit less expensive.

[johnnymk]

Ah, yes, the fabulous Chevy 302 that they put in the first Z28s. They were excellent for TransAm type of racing but I don't recall how they did at the strip. I know you can duplicate the 302. I think it was a 327 with a 283 crank. Of course, it had a special cam and special heads and exhaust system.
Another thing about early Pontiac engines: the 389 was a better engine than the 400. I don't have any figures to prove it, but ask any GTO nut. It was the king of the drags in it's class in the mid sixties.

[natem02]

It didn't fare to terribly well on the strip mainly because peak torque was a little high in the powerband and those early Zs didn't come with a whole lot of rubber to lay power down with. I doubt anyone bought a Z/28 to drag race, thats what ZL-1 and COPO cars were for.

[OC]

Why would I go with a 302 or 327 instead of the 415 I have in mind? Like I said, the goal of this project is "too much is just enough".

As to the supercharger - everybody does those. I like to do things that are a bit unusual, hence the turbo. Also, given the same boost levels, a turbocharged engine will make more power than a supercharged engine because a supercharger takes 35-40hp to turn when it's making full boost. Turbos on the other hand cost little if any power.

My turbocharged and intercooled 415 will run circles around any streetable 302 or 327 you'd care to use.

-OC

[johnnymk]

Yes, it may, but at what cost? Turbochargers and the related components(special pistons,crankshaft,headers,intercooler adapters and possible modifications to the block, i.e. O-rings)will run up the cost to this project dramatically. And there is such a thing as turbo lag.
I was at the Super Ford meet at Reading, Pa. this summer where they had a bunch of turbocharged Mustangs. Half the time, upon launching, the cars would get real squirrelly because they had to rev the engines so high to get in the boost range.
I am cheap and don't like to pay big bucks for anything. I like readily available engines with as little custom machining or fabrication as possible. I look for bang for the buck.
Of course, if it's long straightaway racing you're talking about, the turbo may do the trick.
Plus, isn't that Firebird a little on the heavy side?

[OC]

The entire cost of the car will run about $9000. As for turbo lag, I'm using the Audi approach - the turbo will be slightly undersized for the application. The Audi and VW 1.8 turbos have very little lag, feeling instead like a larger engine. It doesn't take much to make 10lbs of boost, like I'm planning, so a huge turbo is not required. It'll limit my top-end power, but that is by design. With a bigger turbo I'd have lag. Also, it'd give me the potential of 850+hp, and that's beyond what I'd want.

To address your list: special pistons, crankshaft, headers, intercooler adapters and possible modifications to the block - you obviously haven't read this entire thread - just about the entire engine will be aftermarket. There is no way that stock rotating components would stand up to the power potential of the engine.

I agree with you that turbos and drag racing are mismatched, but I am not going drag racing - turbos are much easier to handle when you don't need a perfect launch.

No, the Firebird is not particularly heavy. Besides, it's not about the weight - it's about the power to weight ratio. To wit:

2001 Corvette Z06 - 3115lbs/385hp = 8.1 lbs/hp
2001 Camaro Z28 - 3439lbs/325hp = 10.6 lbs/hp
2000 BMW M Coupe - 3131lbs/240hp = 13 lbs/hp
2000 Acura NSX-T - 3208lbs/290hp = 11 lbs/hp
2001 Porsche 911 Turbo - 3495lbs/415hp = 8.4 lbs/hp

and my 1989-ish Firebird, based on my best estimates: 3334lbs/650hp = 5.2 lbs/hp

Sure, some cars will be able to get me in the corners, but in day-to-day freeway driving I'll eat them alive.

Oh, and for bang for the buck - considering the resulting performance - for $9000, what could compete with me?

-OC

[johnnymk]

For $9000, yes, you could do a lot. That's way out of my budget. I like to race occasionally, but I can think of a lot more ways to spend that kind of money. But like I said, I am cheap!

[natem02]

Go with either smalled displacement and a poweradder or a big naturally aspirated engine, superchargers are still the best for the money, turbos sap a bit more horsepower than people realize because they create a lot of backpressure on the exhaust, if you must go with a turbo system its really better if you use a twin turbo setup because a single turbo has problems creating enough volume to feed a V8(especially if you stick to that 415). There is no way in hell that the stock suspension setup on that Bird will have any chance of standing up to the huge ammount of torque you're throwing at it. That unibody will twist like crazy and that solid rear axle will snap like a twig. Even if you do the substantial chassis mods needed, it won't hook up on street tires(and not much better on drag radials). You'll probably need a 12" slick and that would protrude out of the wheel well and look really goofy. The only car I can think of off hand that responds well to that level of power is a Corvette(C4 or C5). They have a much better chassis than F-body cars. Anything over 400hp and you start to run into difficulties on 3rd gen F-bodies.

[OC]

The suspension will certainly NOT be stock. The rear axle will be a Ford 9" with 35 spline axles, 2.8 r&p, and a TrueTrac limited slip. Suspension hard parts will probably come from Global West, Eibach, and Koni. Brakes by Baer.

With just the 415, no turbo, the stock components will survive. The entire suspension, rear axle, 4L80E, subframe connectors, and 6-point roll cage will be put in place before I add the turbo.

-OC

[natem02]

None of the stock drivetrain components will stand up to that 415. I blew up a rear-end and destroyed a flexplate in my wimpy 305(175hp, 225lbs) powered '86 Camaro(basically the same drivetrain as your car). Build up your suspension before you put that new crate engine in.