PRO STOCK TO PRO STREET

> DETUNING A HEAD-KICKING PRO STOCK HEMI FOR THE STREET

STORY ANDREW BROADLEY PHOTOS YIANNI ASPRADAKIS

GRUNT HUNT

> DETUNING A HEAD-KICKING PRO STOCK HEMI FOR THE STREET

TYPICALLY, these Grunt Hunt features focus on squeezing every available skerrick of horsepower out of an engine for a given application, but this time around things are a little different. Brilliantly, a customer of Warspeed in Sydney’s west has decided to shoehorn a bona-fide Pro Stock Hemi into a Dodge Charger, which he then plans to register and drive on the street. It’s outrageous and it’s silly and we love it, but it’s not without its challenges.

Aside from the physical enormity of the thing, the central issue is that a 10,500rpm, 500ci race engine with 17:1 compression, aluminium connecting rods and over an inch of valve lift is in no way suitable for street use.

With that in mind, Troy from Warspeed has been tasked with ‘toning down’ the 1400hp monster so it can be used and abused on a regular basis.

“It’s a big, huge, tower of power!”

Troy enthuses. “It’s based on what they call a Hemi 99. I presume it was in use in America between 1999 and 2005, because then they came out with the Hemi 06. It’s a really odd engine, but a really cool engine. It came here in pieces and we had to reconstruct it and turn it from Pro Stock to Pro Street. We had to make it as reliable as we could for a street car and downgrade the power a little bit. Realistically it should just sit there idling in traffic – that’s the plan.”

The first order of business was to revise the rotating assembly, switching out the alloy rods for some steel items, and fitting pistons with a lower compression height to drop the comp from a lofty 17:1 to an E85-friendly 13.5:1. With most production-based engines this could be done easily with off-the-shelf parts, but in this instance it required a great deal of research and custom-made, one-off components.

“I have a strong working relationship with Kavanagh Auto Parts in Victoria who supply a lot of my parts, and between the two of us we’ve been able to get to the bottom of it,” says Troy.

“Diamond no longer produces the piston that was in this engine, so they’ve had to come up with a new billet forging for it. The bore was 4.680in, but we couldn’t get a ring package to work for a street car as opposed to a full-on drag-race ring. So we had to step the bore up to 4.695in, which gives us 504ci now.”

The engine runs six-inch rods – a common small-block Chev length – but Honda journals and big-block Chev-style gudgeon pins meant replacements were not a straightforward proposition. Troy looked to Argo Engineering in Newcastle, who knocked up a set of custom steel rods to suit. “Because everything for this engine is so unique, nothing about it was easy,” Troy says. “We had to work in with Diamond and with Argo, and see what we could come up with to make this engine work.”

The camshaft that came out of the engine was a whopper, with 65mm roller-bearing journals, 1.1in of lift, and 276/310@.050 duration. “It had a really big split,” says Troy. “Traditionally we see 8-10 degrees split on a camshaft; maybe on an LS we’d use 13 degrees because they have such a good intake port as opposed to a poor exhaust port, but this thing has a killer intake port.

It also has a killer exhaust port, just not as killer as the intake – hence the camshaft design.”

The new cam is a COMP solid-roller, and lift has been reduced to 0.875in.

This has allowed Troy to reduce the skyhigh valve spring pressures the engine used to have. “It had 500lb on the seat, and my spring tester maxes out at 1400lb and it blew that off the scale, so I don’t actually know what nose pressure it had when it came in!” he says. “We’ve backed it down now to a friendly 300lb and 875lb on the nose, so it’s a lot nicer spring tension for the street.”

As you’d expect, the engine is loaded with weapons-grade valvetrain components, including meaty Jesel keyway lifters, Jesel shaft rockers, and monstrous titanium valves that measure 2.6in on the intake side and 1.8in on

NORMALLY WE CHARGE PEOPLE TO MAKE POWER, BUT WE’RE PULLING POWER OUT OF THIS TO MAKE IT A STREET ENGINE. IT GOES AGAINST ALL ODDS!

BALANCING ACT

THERE was a great deal of work involved in balancing the new rotating assembly, which ultimately called for a combination of internal and external balancing.

“The Sonny Bryant crankshaft is designed to spin to 10,500rpm, so it’s small and lightweight, but because it’s so small in the counterweights, it already had a lot of Mallory,” Troy says.

“When we came to balance it, because we’d added weight with the conrods, the balancing factor became a massive issue.

“Every counterweight already had four slugs of Mallory, so potentially you have a $5000-$6000 crankshaft with about $3000 worth of Mallory metal already in it, and when we went to balance it we really struggled.

“We could not make the engine fully internally balanced because we couldn’t get enough weight in there, and we had to somewhat externally balance it. Where we needed to remove weight we couldn’t, because there was none to remove. And where we wanted to add weight we couldn’t, because it already had Mallory in there.

“We actually had to make an offset counterweight that bolted on to the balancer, and we’ve had to do the same on the flywheel as well, so it’s a combination of both just to get it right.

We couldn’t go to a new crankshaft, because the counterweight clearance to the bottom of the piston wouldn’t have worked either. It messed with everyone’s heads trying to get it right, but in the end it was [Wayne] Newby to the rescue, who machined up the counterweight for me.”

the exhaust. “The valve layout in this engine is quite unique in that the lifters don’t sit next to each other; there’s a lot of offset there,” says Troy. “The intake lifter is up a lot higher than the exhaust lifter, so the valve layout inside the cylinder head is the same. It’s got the layout of a traditional Hemi head, but the combustion chamber is very similar to a small-block Chev because it’s such a small chamber. You would normally look at a Hemi combustion chamber on a Fuel head or an Alcohol head and they have a really large combustion chamber – close to 200cc – whereas this only has a 53cc chamber, aimed to get what was 17:1 compression into it.”

Oiling is critical on a big-rpm engine such as this, and Troy was blown away by the liberal use of Devcon to smooth the block’s internal surfaces and aid oil drain-back. There are lines from the cylinder heads back down to the pan that deliver oil directly at the scavenge point for the five-stage Magnuson oil pump.

Gone are the mega-buck carbies the engine would have run in its Pro Stock days. Troy has instead fitted a set of off-the-shelf 1050 Holley Dominators, which have been modified locally to suit corn juice. They sit atop a fabricated HRE tunnel-ram intake.

“I’m charging the customer to pull power out of this engine, which goes against all odds!”

Troy says. “Normally we charge people to make power, but we’re pulling power out and making it a street engine. There are so many unique ideas with this thing – it’s just cool. Yes, it has done my head in, but at the same time it’s been really cool to work on something that’s so leftfield.”

So with all the hard work done, how much of the engine’s 1400hp output has been sacrificed in the name of streetability?

“I like to downplay expectations around power, but I think it should realistically go over 1000hp [on E85],” says Troy. “We’ll still have to turn it to 8500rpm, because it has such a small stroke. It’s close to a 4.7in bore with only a 3.640in stroke, so you have basically the samesize stroke as a factory LS, but with a 4.7in bore. That means you have a lot of cylinder to fill, and the only way we’re going to fill it is by revving it!” s

I LIKE TO DOWNPLAY EXPECTATIONS AROUND POWER, BUT I THINK IT SHOULD REALISTICALLY GO OVER 1000HP ON E85