An Interview with Steve Hendren of Hendren Racing Engines

hendren-logo.pngHendren Racing Engines is one of the largest and most respected Crate Engine Rebuilders in the nation. We are very pleased to announce that Steve Hendren has agreed to be a technical expert for Crate Insider. We had a chance to talk with Steve Hendren and ask him for his view on some of the current issues circulating around Crate engines.

CI: There was been a lot of talk lately about the high cost of rebuilding Crate engines. I’ve seen prices called out anywhere from $2800 to $7000. Can you comment on that?

SH: I think that the $7000 dollar figure is greatly inflated and horribly inaccurate. Someone would literally have to be insane to pay $7000 to rebuild a $5500 engine. With that being said, the $2800 figure you mentioned is actually pretty accurate. I think on average a completely legal rebuild will cost in the neighborhood of $2800-$3300 from pretty much any crate engine builder in the industry. We have had some engines that ran close to or a little over $4000. But, those were engines that had been severely damaged from some type of engine failure. In those cases, it was still more cost effective to the customer to fix what he already owned rather than purchase a new engine.

The crate engine rebuild market is actually very self-governing. All of the rebuilders in the country are well within the same price range. The parts and components that go into these engines are priced by GM, so the differences in rebuild price from builder to builder will usually be our differences in labor prices. Of course, labor prices are usually determined by the location of the business, overhead, and the market you’re competing in. In general though, it’s very cost effective to rebuild your 604 crate engine. The 602 engine is a different story, and rarely worth going through when it’s tired or worn out. This is directly due to the cost of the GM components, and the fact that the labor processes are the same for the 602 and the 604.

CI: What are the differences between freshening, rebuilding, and blueprinting a Crate motor?

SH: Essentially all three are the same. When you rebuild one of these engines, you must go by the specs that GM provides in the engine technical manual. This is your blueprint that you must follow. So, when we say that we will freshen and blueprint your engine, we are making sure that all machine work stays within the specs that GM allows. As an example, the GM book calls for the combustion chamber volume on a 604 cylinder head to be 62cc’s, plus or minus 2cc’s. Obviously we want to be as close to the minimum of 60cc’s as possible, but not put our customer, or ourselves, in danger of being illegal. So, we make all of our heads between 61-62cc’s. This is what blueprinting actually is, nothing more, nothing less. In the machining world, a blueprint is nothing more than a drawing or a spec sheet that gives you plus or minus tolerances when machining.

CI: How much of a horsepower boost can one expect from a rebuilt motor?

SH: It honestly depends on what you own to start with. If you bring me a worn out engine that’s had its tongue hanging out for the last half of your race season, you’ll see a significant gain once it’s fresh and back to pretty much new condition. But that goes with any type of racing engine, and is not limited to crate engines. If you’re looking for an answer with specific horsepower numbers, it wouldn't be accurate if I just said some random number. Basically we try our best to make each engine the exact same when it leaves our shop. We shoot for our stuff to be in that 395-405hp range at the rear tires. If you have a worn out engine making 375-385hp at the rear tires before it’s freshened, well, you can do that math.

CI: Can you comment on the latest talk in regards to people rebuilding new 604 engines either before they are raced, or within one or two races after they are new? Is there a big advantage to rebuilding a brand new engine?

SH: Honestly it all depends on what you get out of the box when you buy a new engine. In other words, you can be an unlucky guy who purchased a new engine that was built on a Friday after lunch. Or, you can purchase an engine that runs great out of the box. That seems to pretty much be the two scenarios that we see on a day-to-day basis. I get phone calls asking what you just asked every day of the week. I always advise people to dyno the new engine, and if it makes power then run it. But, if it’s a turd out of the box, then go through it and bring it up to snuff. Unfortunately, once you buy a crate engine, you own it regardless of how it runs. You can’t go back to GM and say, “Fix this engine, it won’t run,” like you could if you purchased a super late model engine from an independent engine builder. So, once you own it, if it won’t run, your only alternatives are to have it gone-through and brought up to speed, deal with it the way it is, or pawn it off on someone else. Some customers choose to simply bypass the guessing game or trial and error process, and just have them gone-through out of the box. I don’t see a problem with this since it’s their choice to spend their money how they wish to spend it on something they already own. They are basically ensuring that their engine is built correctly and running correctly to start with, at a minimal expense since everything in the engine is new.

So, essentially I’m answering your question by saying no, there is no big advantage power wise in going through a new engine unless you have one that simply won’t run.

CI: If there’s not a big difference in horsepower, what are the primary reasons why someone should have their engine rebuilt?

SH: On a new engine, I’d say peace of mind in knowing what they own is functioning to the best of its ability. On a well-used engine, it’s relatively obvious why one would be due to get rebuilt.

That being said, I advise my customers and really anyone that calls and asks, to run leak down tests on their engine on a regular basis. I recommend the leak down test because it’s the only effective way to determine how well the engine is sealed up. What I mean by this is that you’ll know very quickly if your rings are shot, or you need a valve job, etc. A lot of people try and run compression checks. This is actually very inaccurate on an engine with a hydraulic cam and lifters. While a compression check will obviously show if you have a cylinder that’s pretty much completely down, that’s about all it will show. I compare the leak down test and compression test to using plastigage vs a dial bore gauge when checking bearing clearance. While both might work, only one is accurate. The problem with a compression test is this......On any hydraulic cam and lifter engine, several lifters will bleed down once the engine is turned off and not building oil pressure. So, when a hydraulic lifter bleeds down, and you spin the engine over to run a compression check, the duration of the cam is automatically kind of falsely shortened. When the duration is shortened, cylinder pressure goes up. So, you could have an engine that has a hole that’s actually down, but don’t know it, because the cylinder pressure is falsely raised because of the nature of the hydraulic lifter. Therefore, we tell everyone to run leak down tests, and when you start seeing 10-12% leak down with the engine cold, it’s time to start thinking about freshening it up.

CI: What are the three most common things that you see, and can share with racers, that cost them power weekly?

SH: The first thing would be people trying to mix fuel. I see this all the time where people try to mix pump gas with 110 fuel. This is simply not a good idea, and it’s a power killer. The biggest problem with this is consistency. If you spend any time on a dyno messing with fuel and the induction system, you’ll see that consistency on a crate engine is key. Jetting is critical! You just can’t be accurate enough with your mixing process to repeat any type of power numbers. While the guy mixing fuel might think he has it down, and can do the same thing every time, he simply can’t. This is largely due to the introduction of pump gas in the equation. I've seen ethanol content from 5%-15% on pumps that say “maximum 10%”, and from pumps that claim “no ethanol.” So, what does a guy have when he mixes pump gas and 110? I have no clue, and neither do they. Does this fresh batch need 75 jets front and back, or 77 jets, or 74 jets? I don’t know, and neither do they. So, we recommend to people that they, at bare minimum, run the cheapest race gas they can find if they are trying to save a dollar on fuel. This is their best chance at making consistent power on a regular basis, and their best chance to avoid burning a motor down because they got their mixture wrong, or their carb is set up to run their mix with no ethanol in the pump gas and they get a load that has 15% ethanol from their normal gas station.

The second common thing I see is guys that don’t run any type of cold air box. If you show me a guy that has his air cleaner half under the hood and half sticking out above the hood with no cold air box, I’ll show you a guy who is throwing away 10-15 FREE horsepower at the rear tires. I can prove this on the chassis dyno all day long. Cold air is critical on these limited horsepower engines! Crate engines don’t have 10-15hp to simply throw away because their engine is breathing and trying to compress 200 + degree inlet temperatures. With a little bit of aluminum work, or by purchasing a pre-made cold air box, you can isolate the air cleaner from under hood temps, and gain back the free power you’re throwing away. People always hope that I can find them 10-15hp in their engine, when a lot of times they can spend a little time and very few dollars to free up 10-15hp themselves.

The third big thing I see is some racers insistence on using air cleaner elements that require oiling in order to filter properly. This type of filter has been common in dirt racing for many years. But, it has a serious drawback when it comes to crate racing. Reference back a bit when I talk about dynoing and how critical jetting is on a crate engine. Now, take your pre-oiled air cleaner element, run a 30-50 lap race in the dust, and let’s go dyno. What you’ll see will shock you. Basically, your oiled filter is now half stopped up with dirt and grit, which limits the air intake of the engine. So what happens when your carb is jetted for a nice clean new air filter, and you now cut the air intake in half? The engine goes way rich, and kills power. How much power can you afford to lose in crate racing? My answer would be none, especially when using a paper element or synthetic element filter will prevent most all of that power loss that you see with an oiled element filter. We are not running 850hp engines where it doesn't matter if we lose 20hp by the end of a race. We can prevent most of this power loss, which has been dyno proven many times, by simply going away from what was once “normal,” and using new and better technology like the synthetic element washable filters that are out there. Hell, even a good Napa filter will help preserve that free power.

CI: Lastly, there is always talk about the escalating cost of racing and making rule changes to “keep the cost down or save the racer money.” As both an engine builder and a racer, what are your comments on the subject?

SH: I’ve raced now since I was 16 years old, at a lot of tracks, and under a lot of sanctioning bodies in the USA and Australia. I’m now 43, so that’s 27 years of racing. I assembled my first engine for my dad when I was 12, so that’s 31 years in the engine business. Out of all that time, I've come to learn one thing: any time a track or sanctioning body starts talking about keeping the escalating cost of racing down, it means I spend more money to race while my engine business makes more money from the racer. So, I’m of the opinion that if it’s not broken, don’t make another rule to try and fix it. The escalating cost of racing has been an issue since the first dude with a steering wheel and four tires went faster than a horse. We see where we are now in comparison. The facts are that as technology increases and expands, so does the cost of racing and everything else in life. All that can be done about it would be to phase out the divisions that people think are out of control in cost, and start new divisions that meet what one might think are the needs of those who can’t afford to race right now. Either that, or offer incentives for racers who might use more cost effective components, much the same as one crate series did with a spec shock. But, creating new rules to limit expenses in pretty much any existing class of racing usually does nothing but cost someone while someone else profits from the next technological advancement that gets around the new rules that are created.

Hendren Racing Engines is located in Rutherfordton, North Carolina. They are certified rebuilders for Fastrak, RUSH, Nesmith and SECA Series. Hendren Racing Engines can be reached at 828-286-0780 and at