I am starting the process of building a pretty serious street/strip engine for an 86 Camaro. I have scrapped the idea of rebuilding the 305, and would like to go a step further than a 350 crate motor.

The plan is to build a healthy engine from scratch which is street drivable, but does not need to be a daily driver. The car will also see some drag strip work.

Here is what I had in mind - any additional ideas/advice would be appreciated.

World Industries small block Chev engine block - 4.125" bore, 4 bolt mains
Eagle 4" steel crank - total displacement 427ci
Eagle H Beam 6" rods
SRP forged pistons - compression around 9:1
Custom ground hydraulic camshaft - 226/234 deg, .520/.580" lift, 114LSA (somthing like that)
Twin turbo - Garret GT30's maybe
Front Mounted Intercooler
Edelbrock heads - 2.05"/1.6" valves, dual springs etc

TH400 auto, full manual valve-body
3000rpm stall convertor

9" diff, with 3.9 or 4.11 gears

Not sure on intake setup just yet - probably fuel injected. Can anyone recommend any good fuel injection setups for forced induction small-block Chevs?

Obviously the fuel and ignition systems etc will be upgraded to match.

Looking for something around 500rwhp at 1bar boost on 98RON fuel and max 6500rpm, and maybe somewhere in the 9 second zone over the quarter, but well mannered enough to drive on the street.

Does anyone have any opinions or advice on this combo?

Anyone built engines like this before? V8s are not new to me, but I have never built a turbo V8 before, and never built a Chev (Holden and Ford V8s mostly - same pushrod design).

 

you should be able to do close to 500 rwhp w/o the turbos and just raise the compression a bit more...if you want that much hp just add a 50-100 shot of N2O for the track. make sure that cam won't hit with that much stroke and H-beams.

 

First off like chas said you could probably do what you want on motor. For that I'd use more cam at least something in the mid-upper 230's duration around .600" lift or more along with at least 10:1 compression if not 11:1. Since you then wouldn't be buying any turbo stuff you could use some of that budget to get a really nice set of heads like some AFR's. Going back to the turbo idea, I have the rest of my thoughts on that below.

I'm not sure how much the pistons are going to like not having much area left for compression height with that long of stroke and rod although I'm sure it has been done. Possibly look into piston availability and maybe using a 5.7" rod to gain some compression height.

Seems like most, including me, use cams that have either the same or less exhaust duration when compaired to the intake. The cam being that small would quite likely work nice as you have it small enough that there's little to no overlap. I think it could stand more overall duration in the cam and being somewhere in the .600" lift area would be nice too, but that one will behave vary well on the street.

Twin turbos aren't needed, but you could do that if you want. I'd personally use a single probably upper 70mm or lower 80mm, and an 88mm would be the absolute largest since they get externally quite a bit bigger after that. 9's shouldn't be a problem with that kind of motor on 15psi pending traction, but it'll be making probably more like 600rwhp or maybe more. I'd get enough turbo rated to go up to around 1000hp or more just so that doesn't become an issue of it being too small since you have more than enough motor to spool up easily.

Overdrive trannies are nice for the street, but a th400 would better suite it for the strip. Price wise a th400 and 700r4 would probably be within a few hundred bucks of each other, but a th400 with a trans brake is SWEET for a turbo car on the strip.

In the 9's you're looking at about 140mph, and with a 3.70 gear and 28" tires the motor would be around 6800rpm through the traps, so that gear seems to more fit what you're looking for.

For fuel injection I have a BS3 setup on mine that works quite well, and I hear that Accel is fairly similar. Kits for fuel injection are kinda nice; Edelbrock, Holley Stealth Ram, and Accel all have kits for just shy of $3000, but you'll probably want to use more fuel injector and fuel pump than what comes with those. Otherwise a victor intake setup for fuel injection wouldn't be a bad place to start.
I guess I have an opinion on that then don't I? That's a lot of typing.

 

Thanks guys.

I wanted to go for twin turbos rated at 450-500hp each for physical size and faster to get on boost, while still being able to support 6500rpm in a 427. I could step up to 600hp GT35 units, which will give me more top end and more room to play with in the future.

Piston selection with a 6" rod and 4" stroke shouldn't be a problem, I know that Eagle does kits for it, and I am pretty sure that SRP and JE both make pistons to suit.

In previous experience, I have always seen turbo cams to have more duration on the exhaust than intake, but as I said, Chevs are a little new to me, perhaps their design would be better with a single pattern - say 234/234, .600", 114LSA?

I considered going the naturally aspirated route with a tunnel ram and twin carbs or Edelbrock Torker II, 250 deg @ 108 LSA cam. Probably a little cheaper, not as nice on the street, and less powerful (I guess 450rwhp or so is still pretty tough on the street)... and there is something really cool about a big cube, big cammed naturally aspirated car...

I always wanted to build a TT V8 though... so I might go with it.

 

If you are going to spend all that time and money on a motor for a street/strip effort thats biased towards "strip", why not spend the money on a big block? Even a basic 454 is bigger, with lots of growth potential (500ci+) and will be substantially stronger than building on a SBC base.

Think about it.... generally, SBC heads are limitted to 220cc-230cc or so. BBC heads are WAY over the 320cc range, with MUCH larger valves, much bigger bores and pistons, and a substantially stronger bottom end and rotating assembly. Seems like a better way to go than the 427 small block IMO.

 

If you look at the Trick Flow top end kits at Summit they have a 500hp kit that, with supporting mods, got me to dyno 405rwhp 333rwtq which was good for mid 11's at 118 with my car being 3300lbs going down track. With a set of AFR's on that big cube motor I bet 500rwhp whouldn't be that hard to do, but you'll need probably a 100-150 shot to get into the 9's from there. On motor I'd do probably a solid roller somewhere in the 250 or 260 area for duration and crank up the lift. For turbos 234/234 sounds nice. I think that reverse split of the turbo cam duration comes in more agressively when you're talking cams in the 250+ intake duration. You don't need to worry at all about spool time with anything that would support your power/e.t. goals on that big of a motor. For example, my 383 starting from 1800rpm and no boost reaches 4psi in 1.5 seconds on the trans brake with a 91mm turbo on quite a rough tune that could likely spool faster.

 

Big block parts are also alot heavier, and more expensive. I don't want the car to be nose heavy - a 427ci small block is a direct replacement for a 350 (and I think 305). Heads aren't really a problem with forced induction, the small block heads will be fine.

 

you can always do a blower/supercharger if your worried about the lag time...it will cost you about the same amount of money either way but minus the lag...but like i said before you can get 500rwhp out of that 427 easily so why do the turbo and add uneeded stress to the engine that u already make the power u want. increase that stall to 3800-4000 and ull be able to break into the 10's on a N/A 427 with a good tune, intake and carb...

 

If you build a BBC with aluminum heads and intake, it will weigh about the same as an iron headed small block, so nose heavy won't be an issue. Any weight added with the BBC is more than made up for with the added torque that the big block will produce. The big block will also not be as peaky as the 427 small block will be.

With what it seems to me you are building, the only 'direct replacement' factor will be that the 427 will drop down onto the same mounts and bolt up to the same trans as the 305/350. Which the big block will also do. Everything else you do will be custom anyway, especially for a turbo setup - cooling system, accessories, exhaust, air intake..... so the same work would be needed whether its a big block or a small block.

 

I doubt my BBC weighs very much more than a factory SBC. My block is considerably heavier than a factory BBC block but I have a lot of lightweight parts in and on it. My car is strictly a race car but the front weight is roughly the same weight as a street car with a SBC.

Saying a BBC is too heavy isn't a good argument. Even in stock trim, it's only about 150 pounds more than a SBC which isn't a lot when you consider how much more potential it has and how much more torque it can produce. Most untouched factory BBC heads flow better than aftermarket SBC heads do so there's a lot more power that can be made with little effort.

Reading the first post, it looks like you're quoting what you've read from a magazine with no consideration on the combination of parts.

 

+1 on solid roller.

 

Thanks guys, you raise some interesting points.

I chose a Dart or World Industries Chev 400 block because they are a little lighter than the stock block, and stronger. I will be using alloy heads as well, not iron. Smaller crank and smaller pistons means less rotating mass, so better response, and less overall weight.

A big block is not a bad idea, but I think I will go with the big cube small block.

I will look into the costs involved in doing a roller cam, as the benefits are great. But the car will be turbo - I always wanted a TT V8, so I am dead set on building one. With 427ci I don't think that lag will be a problem with the right turbos - GT3076's or GT35's should do nicely.

The car should be able to be driven quite nicely on the street with reduced boost levels, while maintaining subtlety and reasonable fuel economy. It will make big power on the dyno and low numbers at the track with the boost cranked up. I could run 25psi on this setup making 1000hp or so, and it shouldn't be a major problem.

 

After talking to a few people who have built similar engine combos and a few engine builders, I have made a few alterations to the plan, and I think I have come up with something that will work.

One thing that came up a few times is people telling me to drop the displacement a bit, use a 5.7" rod and a piston with a better compression height.

So here is the revised plan:

World Industries Motown cast iron block - 4 bolt billet caps, 4.155" bore
Eagle/Scat forged 3.75" crank - give 407ci displacement
Eagle/Scat forged 5.7" H-Beams
SRP -16cc pistons - 9.0:1 compression
Twin Garrett GT35 turbos (0.82 rear housing)
Custom ground solid roller cam - 245deg, .600", 114LSA
Dart Iron Eagle 230cc Heads (300cfm or 600+hp)

I plugged these figures into a dyno program, and the figures were surprising - and I confirmed whether they are accurate with an engine builder.

1232hp (at flywheel) at 6500rpm on 25psi - just enough for the street