Forum: HoseHeads Sprint Car General Forum (go)
Moderators: dirtonly  /  dmantx  /  hosehead

OK, here's question for the folks who've been around this sport longer than me:

Since the early days of say, WoO, or sprints in general, the basic engine is still the same: injected small block Chevy on methanol. So what changes explain the increase in HP from 500 back in the day to 900 HP nowadays?

(MInthess, please don't try to hijack the thread with Ford diatribe...)

Some things that have changed,

Air flow through Cylinder Heads

Cam Dynamics

Reduced weight of rotating parts

Increased strengthof materials to allow higher RPM limits

then comes fine tuning in piston design, better ignition, better fuel managment, better exhaust configuration, and portable air meters to allow tuners to extract optimum tune.

Yes, increased strength of materials a big change, like super strong aluminum, titanium, better cooling, dry sump 10 or 12 quart very thin racing oils, even much better seals.  GM wasn't going to put stuff like that in a street engine and ask the customer to pay an extra $30,000 more for their Impala's 327.  Wasn't needed.  Plus most of that stuff came about in 70s and 80s.  To me the big change that started the HP climb where I live was the Hilborn fuel injection stacks.  Prior to that, between 1960 something and 1965 electronic fuel injected 427 Ford motors were winning all the "sprint car" races locally, called super modifieds back then. The 327 with a 4 barrel carb couldn't compete, then about 1966 a guess a few 327s showed up with Hilborn fuel injection and that was all she wrote and the march to the smc engine was all there was until Karl Kinser got together with Mopar for  two years in the WoO and dominated with Mark behind the wheel.  Also back in the day, sprint car/super modified engines were just bought at the dealer and almost nothing done to them.  Time for a rebuild and they just sold the old engine for $200 and bought a new one for $400 or $500.

But HP doesn't always win.  I remember when Lance Blevins told me that of the three engines he had in the hauler/car, the one that dyno'ed at 40 less HP was the faster, could have been several reasons for that though.

Lawlessness + liberalism = HELL -  NYC, Detroit, Chicago, 
Seattle, LA  Who the H runs those cities. 

Basically the three major things in any engine that dictates horspower are heads, injector, camshaft.  Yes ring packages, rocker arm ratios, oil pan designs, and even oil pumps do contribute as well.

As far as horsepower goes if you can't get it to the ground then it isn't any good.  Most 410's are in the 910-930 range BUT I know of quite a few guys that have engines that are in the mid to high 800 range that race them because they don't blow the tires off everytime they touch the throttle.

The major block casting manufactures made major improvements over what came from GM. Cam location, webbing, cross bolting the cranks.  Heads at 1 time , when I ran,  brodix 10 then it went to 12 heads. Today there are a multitude of choices. The brodix product is still a top choice. Injection and fuel systems in general. I've said it before, that 410 chevy really isn't a chevy. 

Not to br real picky but most sprincars use 15-50 wt oil. not real thin oil.  Dry sumps are 8-9 qts of oil and I never heard of electronic feul injected Fords in the 1960-65 era.  USAC had a 302 cube limit for years abd were in the 500-550 hp range.  WOO  and PENN. andother tracts had no cubic inch limit till sometime in 1980 s I think.  A 500 cube big block was ok.  Some used big  block to qualify and sbc to race with.  Sounds like alot of work.  Yes, cams, heads and big injection and ignition are reasons for hp  gains.    Some engine builders have dyno sheets that are jacked up to please engine buyers.  Do not believe everything you read.  I think Wesmar is very honest on dyno hp sheets.  They might be ones to answer that question.

At one time here in pa big blocks were king. You had to have a soft right foot because if you didn't you would spin out so easy. 

Yea, I don't think they had electronic FI in the 1960s either.... computers were too big! Plus I followed drag racing back then (when it was more homebuilt & creative) & never hoid of it...

Thanks Wesmar!

"As far as horsepower goes if you can't get it to the ground then it isn't any good.".

Yea, I think we all know that.... exactly what Karl Kinser said in his recent (& great) interview: "God & Moses with a sidecar couldn't control 900 HP" (Or something along those lines....)

It would be interesting to compare track records from 500 HP days to present times... no way are they 9/5 faster now

What about higher compression ratio? 

Or not?

A majority of the hp increase is the heads are physically much bigger now with taller raised intake runners and bigger matching injection to go along. Not necessarily bigger cc runners, just taller with air flow more straight down on top of the piston. The most other significant advance is the raised bigger cam block. The raised bigger diameter cam and short pushrods allow for more radical/precise cam profiles. It is a small fraction of the horsepower gain compared to raised intake runner heads though. SOD tire rule would negate all of it though.

 
 
 
They don't even know how to spell sprint car 
much less chromoly...http://www.ycmco.com

Sprintcar engine development has been much like all other engine development. If you look at a modern street car the horsepower is much higher and more fuel efficient than years past. Rotating weight is king the less work the engine has to do the more potential power that can be produced. torque is huge for any racecar anytime the "loud pedal" is pressed torque makes the car accelerate. The last piece to the puzzle is flow matching the injectors ports and polishing them to have the best amount of air to go into the heads along with exhaust ports will cause ideal fuel/air mixture leads to more power. 

OK, one more. A friend who's rebuilt street engines told me that they get to 410 by boring, not stroking. 

True? But I guess since they're purpose built racing blocks, no need to bore, so I guess the question should be "is it a longer stroke than say, a stock 350?"

The block is a 350 small block chevy and from there it is bore and stroke. If I was able to upload all the synonyms sheets on my 410 engine and older engines it would make a great read for engineers but quite boring for most. One misconception that people don't realize is 900bhp is only at a small band on the rpm scale. 

A stock 350 Chevy had a bore/stroke of 4.00  3.48.  A 400 sbc is closer to to what is ran in sprints with a bore/stroke of 4.125x3.75. Likely most 410's start out at 4.125x3.80.  Rebuilds/freshens may get a .002 overbore to get fresh bores. 4.145 x3.8 nets 410.2 ci. 

An aluminum 410 engine is actually 406ci cold when it heats up and expands it becomes 410ci. This is why Donny had his motor pumped a few times at nationals a few years back because it overheated. 

The Dyno,it allows engine builders to test and find horsepower.

Thank you for sharing your thoughts.  We appreciate you and your expertise on everything sprint car engine.