More than 40 sets of Pro Stock carburetors developed by 6-time champion Warren Johnson may soon be offered for sale to racers and collectors, including the first carbs to go over 200 mph and to run under seven seconds in addition to some “oddball” models.
“Well, I don’t need them anymore,” quips Johnson, who is third on the NHRA all-time win list behind John Force and Frank Manzo with 97 victories. “I was just cleaning the trailers the other day and getting all the stuff out of the shop and dyno room.”
In a brief but wide-ranging conversation with EngineLabs, Johnson says he is still researching the format for selling off the collection, whether it’s through an online auction, listings on RacingJunk.com or just a regular garage sale. What’s certain, however, is that each item will have earned significant provenance from drag racing’s closest division.
“In essence, it’s the history of Pro Stock racing, as far as Dominator carburetors are concerned,” adds Johnson, who ruled the ‘90s with five championship titles in arguably the most technologically competitive class of drag racing. “Every one of them is serial numbered. All the specs when I built them are all in the log books and the run books. The first 6-second carbs are in there. First 200 mph carbs are in there. All the stuff is intact. Once we developed something better, we put the other carbs on the shelf.”
Breaking barriers and setting records
Johnson broke the 200 mph barrier in 1997 at Richmond, Virginia, running 6.894 at 200.13 mph during qualifying, then eclipsing that mark with a 6.883 at 200.53 mph in the first round. Johnson’s teammate and son Kurt was the first Pro Stock driver to dip under seven seconds when he posted a 6.988 in 1994 at Englishtown. Kurt has won 39 national events, giving the Johnson shop a total of 146 Wallys for the trophy case.
We expect to be 80 horsepower off in the first hit.–Warren Johnson, Pro Stock engine builder
As for any tricks that could be discovered after tearing down a set of carbs?
“I’m sure we’ve done a number of things different or contrary to what everyone else is doing, but that’s all in the line of development,” says Johnson. “There’s a lot of oddball stuff. There are some Autolite inline 4-barrels still in the boxes. As soon as NHRA heard I had those things, they banned them right away.”
And what about the intake manifolds?
“I can see someone buying them and making man-cave trophies,” adds Johnson. “Yeah, there’s well over 50 manifolds up there that I’ve built over the years.”
Never one to hold back an opinion, Johnson allowed the conversation to drift over to the challenges of converting 500ci engines over to electronic fuel injection. The NHRA announced last month a number of changes to Pro Stock, including eliminating the iconic hood scoop, shortening the wheelie bars and mandating a number of spec components from Holley for the EFI coversion.
“I’ve been on NHRA since 1989 to put fuel injection on these cars. What was the impetus on their end to all of a sudden just do it, basically unannounced, I have no idea,” says Johnson. “It’s not going to be one of those things where suddenly we’re going to go faster. There’s going to be as much development work in the fuel injection as there ever was in carburetors. Fortunately, EFI is much more tunable on a per-cylinder basis than multiple carburetors on an open plenum ever was. Ultimately we’ll be able to get the engines much more efficient. Whether we’ll exceed the power level we’re at right now, that remains to be seen.”
Tackling higher manifold temperatures
One of the first challenges for the Pro Stock engine builder will be higher temperatures in the intake manifold.
“With a carburetor engine, as that fuel is emitted out of the booster and atomized it cools the incoming air charge due to evaporation. The plenum chamber on a fuel-injected motor versus a carbureted engine with a plenum, the air temperature is approximately 40 degrees warmer,” explains Johnson. “Every 10 degrees in a 500 inch motor is about 20 to 21 horsepower. So we expect to be 80 horsepower off in the first hit. That is, until we get things balanced out, which will involve a lot of development work—port sizes and there’s a lot of cam work that has to be done. Ultimately, I still consider it a step in the right direction.
“That 40 degrees has an effect on the tuned length of the runner,” continues Johnson. “It’s going to be a learning experience for just about everybody. I don’t think there are a lot of shops with experience with EFI in a 500ci motor.”
Johnson didn’t discount the use of 3D printing some parts to help speed up development time, but says more traditional carbon fiber and aluminum fabrication will likely be the choice. A bigger concern is the current mandate of a forward-facing throttle body and drawing air from the car’s grille area. Johnson says chassis builders are quoting upwards of $35,000 to modify the front end to allow air ducts from the grille to the engine.
“I prefer to have it in the back and use cowl induction. That eliminates a lot of headaches as far as duct work,” says Johnson. “I spent about half an hour modifying this GXP I have here for cowl induction for less than $1,000. [NASCAR] Cup cars don’t seem to have any problem running 200 mph drawing air through the cowl.”
Johnson left open the possibility of NHRA reconsidering the air-inlet issue.
“I think they’re in a wait and see attitude. Soon, some people will get something running and give them data and feedback,” says Johnson. “Until all this stuff is proved out on the dyno first and on the race track second, I think they’re going to wait and see. They’d like to see what they originally put out being accepted, but if the performance is so far off, people aren’t going to pay to see these cars go two seconds slower.”
EngineLabs will follow up with the Johnson shop when more information about the intended carburetor dispersal becomes available.