An old game...trying to model my car

[kawahonda]

Could use some help. The camshaft stuff I don't know what to put for EVO, EVC, etc.

Everything else should be semi close.

[kawahonda]

Here's what I know about the cam. Any hunches to make what I input more accurate?

The simulation ran 14.6 with that on street tires and 3700 race weight, 3.73 gears with 727 and 1800 stall with that screenshot.

[Chryco Psycho]

I believe the factory service manual or maybe it was the D C engine manual that listed the valve opening & closing degree for factory cams , I know I have had that info , just don't have it handy now , 14.6 is probably accurate tho

[bennydodge]

If were talking stock 340 cam, factory service manual says:
IVO 22 deg
IVC 66 deg
EVO 74 deg
EVC 22 deg

Overlap is 44 deg.

I guess a trip to the racetrack would tell you what it really runs. Road tests of the day show stock 340's ran anywhere from high 13's to mid 15's.

[kawahonda]

Perfect, thanks for thumbing that up, very helpful. I'll input that number. I'll also change the CFM from 650 to 630 on the carb.

I was messing around with the IVO/IVC/EVO/EVC numbers last night and I made the car into a 17.6 second car. LOL.

Hopefully with the cam numbers that you provided I can get that graph to resemble what a 340 "actually" does. It should be at 275-300 HP stock at ~6,000 RPM. Basically, it needs to peak a little higher than 275HP and go a little higher than 5,000 RPM.

Torque needs to be over 340 and needs to peak at about 3200 RPM'ish.

That's pretty much all I can do for the engine. The options with the heads are not too much. I have it on "Low performance, stock ports." My options are wedge, canted, and 4-valves with plenty of "porting" options in between

The game is called Burnout Championship Drag Racing. It was forgettable game that came out around 1998. To this day, there has yet to be anything comparable that has the amount of detail that you see, and that's just the engine tab!

[bennydodge]

Sounds cool...I would certainly use "high performance" when describing early 340 heads, VERY good small block head for the era. The later 340's with the small valve 360 heads were more of a compromise.

[kawahonda]

OK, here are the results.

500 ft elevation, 50F day.

First off, I tried to faithfully recreate the HP and torque curve of my stock 340 motor. About the only thing I can say motor-wise that has been done is a re-curved distributor with really good timing. See first picture for the spec and let me your feedback. I have the compression at 10.3:1, but I can certainly lower it to 10.1:1. I have the heads on "Low Performance with Large valves". Headers is "Stock Manifolds", although "Stock HiPO manifolds" is an option but it increases the HP and TQ too much to where I don't think it's faithful.

Obviously this assumes a "brand new" engine, but I landed at:

310 HP @ 5184 RPM
350 TQ @ 3520 RPM

If I changed the heads to "Stock heads and valves" then I land at:

277 HP @ 4928 RPM
340 TQ @ 3456 RPM

If I bump up the compression to 10.5:1 and keep "stock heads and valves" then I land at:

280 HP @ 4928 RPM
343 TQ @ 3456 RPM

Something tells me after editing this message I should probably take the more "conservative" approach and use either the 2nd or the 3rd option. The rest of this message is using the first option (310 HP), assuming that the factory 340 makes power over what is listed.

For my specific vehicle, I put in 3720lbs (race weight), 3.73 gearing, adjusted the transmission to reflect a 727. I stuck in 1900 RPM as a stall speed (confirmed in my car). I used a '72 Duster because the 1970 'Cuda looked like crap and it had a big ass wing on the back of it. I adjusted the weight of the Duster accordingly to reflect a challenger, did not mess with anything else suspension/chassis wise.

I chose "stock" tires, with 26.1" diameter. I didn't know anything else to adjust on the tire screen so I left the rest alone.

After running 16.8-17.8, I was banging my head trying to figure out why my car is so slow. The game has telemetry data, so I took a look to see what my rear tire was doing. Turns out, it was spinning...like all the time. I have 235/60/15 Mickey Thompson Sportman S/Ts, and I guarantee you that they do not break loose like that, even when I stomp on it. For the "stock tire" profile, it was spinning even in second gear several times. Before I hit second gear, the tires kept breaking loose (zero traction) like 5-6 times per run. No way that's realistic....my traction on a stockish 340 motor is not that limited with my tires, partially because it's just not putting out that much torque down low.

I changed the tires to "high performance street tires". Now, it will break loose for a brief moment only once before hitting second gear (sometimes none, but I have to be very careful). I ran several runs.

My best run was 14.35 without the tire breaking loose at all. I'm only able to do this 20% of the time.
My normal run with tire spin off the line is 14.7-14.8.

I'll probably re-do this with the more conservative 277HP estimate. Then I'll create a "stroker" build and see what that does for me.

If you guys want to join me in being bored and not being out in the 100F heat in the garage, you can provide me the specs of your car, including weight, gearing, tranny, etc. I can make a few runs...and even better if you have a time slip to compare. I have a feeling this simulation seems fairly accurate, but who knows. It's pretty fun though!

[kawahonda]

At

277 HP @ 4928 RPM
340 TQ @ 3456 RPM

my ET is 14.7 to 15.2 out of 5 runs, depending on launch.

[RUNCHARGER]

I've seen dyno tests of dog stock 340's at 310HP to 315HP so that part is right on.

[kawahonda]

Sheldon, how much RPM?

Assuming 5200ish?

[RUNCHARGER]

Yes: Around 5200.