Road-racing Engine

[Grabinov911]

Genius Down Under. Still LOVE those Shifter wheels man. If I ever get back to Aus you better hide your car. On second thought, if I ever get back to Aus, I may be there for good...

Posted on pro-touring.com. I'm a little worried they're just gonna tell me to drop in a $20k fuel injected crate hemi. We'll see what they say.

i would talk to the pro-touring guys, like Dan from Hotchkis, his roadrunner annihilates alot of newer cars on the road tracks.
and they build those engines for road racing etc.

www.protouringmopar.com
www.pro-touring.com
www.hotchkis.com

 

[Kern Dog]

You asked me to jump in on this one, but I'm not sure I have much to add. There have been some great responses so far.
Suspension: At speed, things happen quickly. A car that handles neutral at 40 mph could get loose at 100. I'd err on the side of slight UNDERsteer rather than using stiff leafs and a big rear bar. Crossing up at 100 mph is extremely difficult to recover from. You want to use 15" tires. If the tires are speed rated for above 100 and they are less than 5 years old, you may be okay with them. SOME tire stores in CA will not mount used or even NEW tires if they are over 5 years old due to liability concerns. Driveline balance is critical. Sustained speeds can make an out of balance driveshaft beat the hell out of the U-joints. Guess what happens when THEY let loose! Your fuel system will be heavily taxed during the run. A 3/8" line is an absolute minimum.
Someone mentioned cooling. I'd suspect that a belt driven fan would be useless with that much airflow, so an electric fan should be considered.
Whatever direction you go with the engine, I'd also err on the side of avoiding detonation by all means. You'll never hear the car pinging itself to death at 100 mph with all the road noise, engine/trans/axle noise, etc. I run 10.73 compression with the same heads as you and mine rattles even with the timing dialed back to 31 degrees and NO vacuum advance. I am working on a few things to reduce the detonation in my engine so I am not nearly as qualified to offer engine help as others here are. I can only tell you what has NOT worked for me. High compression and a mild camshaft isn't a winning combination because it creates too much cylinder pressure, making it more likely to detonate. I've received good advice in my thread.."Living with 10.8 compression on the street."
A 2.94 or even a 2.76 gear could help you a bunch. The 500 cid engine will still be a runner with the 2.94 since the long stroke doesn't need 4.10 gears to go fast. I have a Gear Vendors unit in the Charger. This reduces the 3.91 diff to 3.05 in overdrive. It still pulls strong in OD at 90+. Even though these stroked cranks are forged, I see no reason to spin them to 6500 rpms. There are online speed calculators to play with that will let you know what RPMs you'd be turning at speed.
Good luck!

 

[Grabinov911]

Latest

OK Gents,

Here's the latest on the Road Racing Engine Build:

Mancini 493 Stroker Kit
Mopar Performance 84cc Heads
Crower custom hydraulic roller cam (see spec sheet below - sorry for the blur)
Crower roller lifters
ARP bolts and studs all over the place
Milodon Road Racing oil pan
440 source front cover and fluid balancer w 440 source high volume water pump and housing (fits with their front cover)

The build is still underway. The cam is in, timing chain on (cam at 4 degrees advance) and the front cover is on after about half a day of fussing with the cam button and the front cover fit. The cam is pretty mild for an engine this big, but at advice of some here and my engine shop I am being pretty conservative. There is no need to go crazy with an engine this big. We'll have plenty of horsepower to go fast.

Next: Intake manifold and carb. Builder likes the Holley HP, probably 800 size, so I'll likely go with that. The motor is meant for road racing, so it needs to run at all RPM ranges and needs to be able to sit at relatively high constant RPM in order to turn 100+ mph for an hour at the Silver State.

Got a pic of the car in current trim as well, with the new Wilwood front discs...

 

[Bolt-Action]

Very cool thread, subscribed!
would love to do this with my 67 Sat, been thinking about a modern hemi to reduce weight out front (?)

 

[Sweet5ltr]

Not trying to get off track, but wouldn't a solid flat tappet or roller camshaft be much more reliable in this type of build for road racing? I've heard nothing but issues coming out of owners with Hydraulic Roller applications in Big Block Mopars due to oiling issues.

I think the Edelbrock Victor, Indy 440-2, or Holley Street Dominator (for hood clearance issues) would be the manifold choices I would be looking at on a big cube build. My vote would be for the Victor. Performer RPM manifold would be a very conservative choice.

 

[Supershafts]

Ok i got in late after you mentioned cams the 1st time, the cam you mentioned the 1st time is a S M ALL cam for a 493.

I can't read the other cam you did get though.

 

[Boise68]

I am drooling. :headbang:

 

[99ss]

Not trying to get off track, but wouldn't a solid flat tappet or roller camshaft be much more reliable in this type of build for road racing? I've heard nothing but issues coming out of owners with Hydraulic Roller applications in Big Block Mopars due to oiling issues.

I think the Edelbrock Victor, Indy 440-2, or Holley Street Dominator (for hood clearance issues) would be the manifold choices I would be looking at on a big cube build. My vote would be for the Victor. Performer RPM manifold would be a very conservative choice.

All depends on the lifter. Hydraulic lifters have come a long way... they can run 7200 rpms for an hour. The ones in my car are limited travel hi rpm lifters made by Morel. .030 of travel.

The bigger the cubes the less rpm you have to run to make power.

 

[Grabinov911]

Thanks for all the input boys.

The lifters are a new hydraulic roller lifter from Crower which, as I mentioned I think, is a favorite of my machine shop - something about the way they heat treat their parts. I have asked over and over about oiling and both Crower and the shop swear they've got it covered. I am not expert enough to know, but will pass along lifter details as I get them. I though about solid and flat cams, but for a car that will see plenty of street time, was assured that the hydraulics - and roller - were the way to go. In many ways, the street engine and road racing engine are a lot alike - when compared to a drag motor which sees very high loads and RPM but for only a few seconds...

Hmmm... Indy Intake... Sexy. I wonder if it will fit under my hood!

Supershafts: I can barely read the photo I took myself, but I think it says:

Advertised Camshaft Specifications
Intake: Duration 312*, .582 lift
Exhaust: Duration 312*, .582 lift

Duration at .050" Lobe Lift:
Intake: 236*
Exhaust: 236*

110* LSA

Intake: .388
Exhaust: .388

 

[Kern Dog]

Good luck fitting anything taller than an Edelbrock Performer RPM under a stock hood. The Indy will not fit. The Victor will not fit. I have an Edelbrock RPM on mine and I have a dropped base air cleaner. You could measure the clearance from the hood to air cleaner lid with a feeler guage.

 

[Grabinov911]

Good luck fitting anything taller than an Edelbrock Performer RPM under a stock hood. The Indy will not fit. The Victor will not fit. I have an Edelbrock RPM on mine and I have a dropped base air cleaner. You could measure the clearance from the hood to air cleaner lid with a feeler guage.

Funny - I thought that might be a problem. I know a guy who actually propped up the back of his hood about 3/8 of an inch to help with this problem. It actually looks pretty cool, but probably plays hell with aerodynamics - if the car has any to begin with.

I had a feeling I'd probably be stuck with the Performer RPM. Actually a really good manifold (have on my 383) but, as was said, pretty conservative for this build...

What air cleaner are you running?

 

[Kern Dog]

I have a Mopar Performance cast aluminum one. I was annoyed to find it didnt allow the hood to close when I first bought it. I measured and schemed to make it work, then I had a guy TIG weld a dropped base into the MP base. The MP kits use a traditional small diameter Mopar air filter, so I kept the outer ring of the base and had it fitted to a cheapie base from a $25 chrome air cleaner assembly. The result was a 2 inch lower profile than the MP air cleaners usually have.

 

[Sweet5ltr]

All depends on the lifter. Hydraulic lifters have come a long way... they can run 7200 rpms for an hour. The ones in my car are limited travel hi rpm lifters made by Morel. .030 of travel.

The bigger the cubes the less rpm you have to run to make power.

99ss,

never heard of any other issues other than with Big Block Mopars and oiling problems with factory blocks. I have a Z06 corvette, I have very little doubt they can't perform at higher rpms.

 

[99ss]

99ss,

never heard of any other issues other than with Big Block Mopars and oiling problems with factory blocks. I have a Z06 corvette, I have very little doubt they can't perform at higher rpms.

So the block is the issue... can it be fixed at the builder?

 

[Grabinov911]

Big Credit Card Day...

FBO HR688 Ignition - The one with the curved/phased distributor
FBO modified Carter mechanical fuel pump with FBO fuel feed lines from pump to carb and filter
FBO custom tuned (pre tuned) Quickfuel Q-850 carb
Mopar M1 Single Plane Intake manifold and related Valley Pan/Gasket
Oh yeah, and MORE of those dang ARP bolts...

I'm taking a risk here with the M1, it's single plane, and it's taller than the stock intake. After lots of contradictory information - from some very reputable places I might add, I decided on the M1 because I believe it will fit with my stock hood and a dropped based air cleaner. I went the single-plane rather than dual plane because I decided to go with the "On an engine that big you'll have plenty of torque, and what you loose on the bottom with a single-plane you'll get back in the mid-range" school of thought rather than the "It doesn't matter how big your engine is. You still need the air to move at low RPM for a street car and the best way to do that is with a dual plane." school of thought.

I really could have gone either way, but had to make a decision, and the Indy dual-plane I was interested in got bad reviews from a couple of good places (you guys all know them) and was almost twice the price. This is going away from Propwash's "model", but I hope it will work. I am going to be running a slightly smaller carb than Prop is (850 vs. 950) so that may get me the air velocity I need at low RPM to make up for the (possible) low RPM velocity loss of the single plane manifold. I'm trying to stay true to my "road racing" build, and if the race-cruise RPM is over 3,000, then the single-plane should be in its element.

Someone will tell me if I'm nuts. OR THE CAR WON'T RUN!!!

 

[2fuzy]

really the only thing you need for sustained high speed operation in a big block mopar is to address the oiling system and valve springs that won't float and appropriate cam choice
address those things a you can run the motor at 6k all day

 

[Dennis H]

My car is comfortable at a sustained 100+. TKO. 3:54 Dana. Minutes, not hours. I have a distant memory of almost ending up in a field at 135 mph due to aerodynamics. Lift. It was so many years ago, I may have had bias tires. It got squirrley. Correct, over-correct. 69 Coronet. Anyone test the limits lately? Silver State Clssic is a dream, pricey though.

 

[2fuzy]

So the block is the issue... can it be fixed at the builder?

not really an oil passage is the issue and all it takes to fix it is a few minutes with a drill and a 1/2 pipe thread tap , bigger pickup tube and ordering full groveed main bearings
the great thing about big block mopars as opposed to most of the other big inch motors of the day is there ability to spin
I kind of wince when everyone builds these big inch strokers and destroys that ability and wonder why they just didn't build a Pontiac

 

[Grabinov911]

And here goes the credit card again. I'm gonna order the oil pump today. Sounds like I need to make sure I get a good (expensive) one!

 

[99ss]

not really an oil passage is the issue and all it takes to fix it is a few minutes with a drill and a 1/2 pipe thread tap , bigger pickup tube and ordering full groveed main bearings
the great thing about big block mopars as opposed to most of the other big inch motors of the day is there ability to spin
I kind of wince when everyone builds these big inch strokers and destroys that ability and wonder why they just didn't build a Pontiac

Isnt the rpms really just a function of a good valve-train though? oiling aside and rod bolts