302 or 347 ????

[Guest]

Let me pick everyones mind.

Looking at the DRB 40.

I have read where Gordon has wickley fast 302's (.030) and some guys use the 347 stroker.

Other details of build:
Weber 48 IDF's
Rousch 200 heads


What did you use ???

And why ???

Starting to collect parts.

BC

 

[Neal]

I have a 347 in work.
Sportsman block...

Forged lower end, 10:1 compression, ported Trickflow heads.

I am planning on 48IDFs. The cam grind is TBD. ~ 450hp / 375tq

The crank and heads were left over from another project. I think I would go 331 if I was to start over. More revs, less side loading, no oil control issues... I had a EFI 347 stroker in my cobra and was bitten by the HP bug. This one will definitely turn the passengers white!

Probably overkill, but hey, you only live once!

 

[Ian K]

I'm most likely going with a high revvin 306,
aftermarket FI, stack injection, forged internals,
girdle, and either AFR or Edlecbrock heads.
May even have Gordon build it if I don't.
Will also be a long rod set up.
Should see over 400HP and sound unbelievable.

Ian

 

I've built a number of different engines for different fast movers. My high revving monsters usually needed a rebuild after two years. Yes they were fun and sounded great but were quite a drain on the check book.

I'm building/had built a 351 stroked. Victor Jr. heads, roller hydraulic cam which limits me to about 7 grand. Forged and NC'ed rods. Forged pistons with NO piston pin to oil control ring clearance problem. Cast steel crank. Balanced pistons, rods, and crank and squared up block. Aluminum flywheel. Topping it off with an 8 stack EFI unit (probably) from Hilborn and an Electromotive TEC-III. Woohoo!

Plenty of torque for those eyeball flattening moments. Lower revs to keep the wear down. Probe (long block builder) offers a 50K mile warranty. Sure hope I don't explode the ZF.

 

I know you will all hate me for this, but has anybody considered shoving a Toyota/Lexus V8 into there?
I know 4-odd litres is fairly poor but those things are smooth, economical, tough, and light.
There would be a fair bit of room for some decent hp/torque improvements with just some upgraded cams or computers there if you wanted to explore it.
Just my 2 cents...

 

[ChrisL]

Adrian,

Being from Australia, you will probably have access to the latest edition of Unique Cars. On page 8 there is an article of an Aus built (by Carbontech) sportcar called the Redback Spyder (Clever name) which uses the Lexus engine outputing a claimed 300+ kW, 320kph top speed and 0-100kmh in 4sec. Thats about 400HP, 200mph, 0-60mph for the rest of you. The car is a contemporary LeMans type mid-engined car and would look great sitting in the gararge next to the GT40 (except for the headlights maybe)

Carbontech

My opinion... the GT40 is not contemporary and would be too much of an odd-ball with the unlikely Japonenglish partnership.

Oh yes, my preference is for the short stroke high reving 302 Windsor. Do they come any better?

[ September 13, 2002: Message edited by: Chris L ]

 

That car is very, very ugly.

 

Eek, that sure is ugly.
A Lexus engine in a 40 I know is completely out of place, but when building a kit car, there aren't exactly stead-fast rules.
I'm mainly curious as to whether or not anybody else has tried/seen V8's other than the Fords in the 40, and if the performance figures/opinions are at all favourable towards other engines.
All part of research...

 

[Jim Rosenthal]

Now, any car that can make a Countach, which is not an attractive car to my eye, look good is really seriously ugly. It is SO ugly that it is kind of cute. Mind you, I would not want to be seen in one.
On your original topic, the advantage of using "old" technology like the Windsor V8 is that parts are relatively cheap, hop-ups are easy, and if you break it another one won;t cost you a fortune. I do not think there's a big market for aftermarket bits for the lexus V8, although it is a good motor by all accounts- I have yet to see a Toyota engine that isn't. Also, the GT40 is a heavy car compared to its' brethren- you need a fairly good sized engine with some real muscle.

 

Thankyou Jim, all very good points.

 

A Cosworth DFV was a consideration for a while. Detuned of course. But that's a 3 liter not a 5. Figured I'd miss the low end torque and 4+ times the cash so I went for old Ford iron. One wonders if the GT chassis could handle 1000 HP.

 

[Julian West]

With regard to building a 302 bottom end - what's the generally accepted limit for a stock crank? I've seen talk of 'crankshaft girdles', could someone tell me the purpose of these?

As I read in Pat Ganahls book, the first weakpoint is the big-end bolts, followed by rods & then pistons.

So based on this what would be a safe rpm/torque/bhp limit for a stock iron 302 block, forged steel rods, forged pistons?

 

[Neal]

I don't think you want to rev beyond a sustained 6300-6500rpm with the stock cast crank. Even with forged rods/pistons.

 

[Ian K]

A girdle is a thick plate that connects
to all of the main studs. If properly
machined and installed, it distributes the
pouinding force each main takes at downstroke
and distributes it across all of the mains.

4 bolt mains are usually beefier, so they
don't need the girdle as much as the 2 bolts
do.

I agree with Neal. Keep the revs to 6500
unless you install a girdle and a better than
stock crank. Forged may not be necessary,
but depending on how much money you're putting
into the engine, the extra may be worth it in
the long haul.

If anyone's interested, I can post some details
concerning valve train travel, piston velocity,
and other such nonsense of 302s, some of the
common strokers, 351Ws, etc. It's interesting
reading, especially when you find out that
a 302 at 7000 RPM will experience less
wear and tear than you might expect.

Ian

[ September 17, 2002: Message edited by: Ian K ]

 

Just bought a pre-loved GTD with a 302 engine (heads ported, otherwise standard) and a Holley 650CFM carby. It refuses to rev beyond 5000rpm, thats about 120mph. What should I expect from this configuration?

 

[Ron Earp]

If it has just stock heads with a mild port then that is about what you can expect - stock 302 heads (E7) castings are dead at 4800 RPM. Beyond that it is noise and power drops off. Also your cam as a lot to do with that as well, if it is a stock cam from 86-95 5.0L years I'd expect that too.

Ron

 

Thanks Ron, that was my worst fear. So I have to think now about what to do with the engine. With the available gearbox ratios (Renault 21T) I would like to get about 6500 rpm.

 

[Ron Earp]

I'd also add or correct, the cam has everything to do with it, along with the heads.

And, the carb you have is fine for a 302. Lots of people over carb their engines, I've done it myself, and know that 600 cfm is just fine for your motor. You see people doing 650s, 750s on these small blocks only to be suprised at poor drivability at low speeds and less than stellar midrange.

R

 

[Ron Earp]

Ian,

Post away, this is good stuff. Much better than "what is the maximum torque my XXXXXX transmission can take" sort of thing.

Ron

 

[Neal]

A set of aftermarket heads like Trickflow, Air Flow Research, Edelbrock, etc. and a mild cam should easily get you to 330-350hp. You are probably at the 250-270 mark now.