351w stroker advice needed

[Andy Dunn]

happy to run your stats 750hp, look on the left on one of the old charts for the info I need
http://www.cobralads.com/desktopdyno/jim.gif

bore
stroke
heads - if common ones cool, if rare, need flow rates and valve sizes
compression
carb size
manifold - signle. dual, tunnel ram, efi
blower any of these or these models or give me these numbers
exhaust - small or large headers - mufflers or straight pipe
camshaft - as much info as you can give and include company and part # if possible

and Yes, nascar engines and sprint car engines are two different beasts. Sprint cars are on a short oval tracka and they need torque to accelerate off the corners. Nascar engines run in a vey narrow band...I think I read it was 300rpm. Because they are running full out most of the time on giant ovals, acceleration out of the corners is not that important since their speed is much more constant.

Andy

[750hp]

Jeff, hmmm.... I don't have an answer for that I'm SURE I read that they ran a car on the dragstrip and it ran around 8.8@156mph. I can't imagine that they'd reconfigure the whole chassis to run a trans, so I'll just have to settle for being caught out as a fool on this post I suppose the old saying; believe none of what you read and half of what you see rings true in this instance....

Andy,
Block Ford SVO 351 (2.75" main journal)
Cylinders 8
Bore 4.030"
Stroke 3.9"

Heads E/Brock Vic Jr (heavily ported)
320cfm inlet
254cfm exhaust @ 28" water .700 lift

Compression 8.5:1

Induction: 90mm throttle body?
Fuel Avgas
Manifold Edelbrock Super Victor (carb style)

Blower YS Trim Vortech
Intercooler 90% ??? Efficient bar/plate 24"x12"x4.5"...
Flow 1500cfm
Pressure ratio ?
Boost Limit 26psi ? (plus or minus a couple...)
Speed 7000
Belt gear ratio 2.64
Surge flow ?
Efficiency 74%
Internal gear ratio 3.45

Exhuast - large tube / open exh

Camshaft (going from memory because the damn speed shop still haven't sent me the spec card!!!)
Crane Solid Roller
specs @ .050
int .564
exh .596

duration
int 236
exh 248

114 lobe centre

Good luck with all of that! If the blower specs or cam specs don't make sense, don't worry about trying to figure it out. If your program spits out a big number, I'll be happy

Craig

[Andy Dunn]

Hey 750hp,

here is my first run attempt at it. I have made a few assumptions here and there to get things to fit.

Heads - I found some ported from data with as high top numbers and used them for flow rates so I feel this is accurate.

Induction - I am never sure what to put for flow for the EFI manifold so I put 750. I also tried 1000 and it barely budged the graph so 750 does not seem too bad.

Blower - this was tricky since the numbers did not all make sense. If I used 7000 speed, the graph was out of control and almost did not work...it was like a zig zag mess so I think the 7000 is really 70,000. The other numbers seemed ok. The 1500cfm for the blower was disallowed...they will not allow input over 1000 so I was limited.

Cam - I was worried I entered the cam stats wrong since all the data is not here and I had to guess...BUT I double checked by picking 3 cams that were similar and the line barely moved which showed that the entered cam data was fine.

I also tried picking the strongest vortech they had VJ-3 and that dropped about 80HP and 80TQ so I left your parameters as a custom unit.

Here you go...a torque monster
http://www.cobralads.com/desktopdyno/-750hp.gif

if you need any changes, let me know

Andy

[750hp]

Andy, thanks for doing that for me! Your entered specs all seem fine, but there must be something weird in the blower details. I actually ran this motor on an engine dyno without the blower and it made a touch under 500hp naturally aspirated (peak rpm used was 6500rpm, and the power curve was still rising)

For the power peak to fall back to 5000rpm and only increase 70 horsepower with the addition of 26psi boost seems a litle odd.

The heads - I'm using a 2.1" intake. Does that affect anything?

I JUST FOUND IT!!!! You're choking my motor...... You've only givin me a 1.06" exhaust valve, not a 1.6" See how it goes when it can breathe

Whew.... you had me worried there for a while!

Thanks,

[Andy Dunn]

well WOW! I think we are over the top on this one but getting closer thanks for catching my exhaust valve typo...it did feel very lopsided but I couldn't see where. I adjusted the intake valve to 2.1. Let me know what you think.

http://www.cobralads.com/desktopdyno/750c.gif

I think maybe that belt gear ratio of 2.64 is off since it is 1.0 on some of the other blowers and this raises or lowers the graph considerably. Pressure ratio we did not know so I kept it same as the others. Let me know if you want to switch any parameters.

[750hp]

Andy, this is the last time I'll bother you (I promise....), but is there a provision for a Vortech YS Trim blower? If so, could you please try putting the standard blower specs for that in place of what we have?

Thanks very much for your trouble - it's fun to see what the computer thinks I'll make. I'm guessing that I'll end up fairly close to my 750rwhp prediction

[Andy Dunn]

hey 750HP

please keep bothering me - I enjoy running the numbers since each engine teaches me something new

Here are the choices we can pick from on Vortech. Do any of these resemble your unit?



and here are some descriptions of these units
http://www.vortechsuperchargers.com/units/

[750hp]

Andy, the V3-J is the closest to what's available there. My peak power figure should be about lineball with the J, but the lowend torque figures will show low rpm losses as compard to the V7 YS Trim

The belt gear ratio is a mystery. I assumed that the ratio would be the ratio of crank pulley teeth to blower pulley teeth ie. 74 & 28. The 1000cfm still looks a little low (but can't change), Pressure ratio ???? - I found out that boost pressure as mentioned is only a peak pressure level (where wastegates in a turbo would be set for example), the pressure ratio is the key to telling the program how much airflow is entering the motor (I think) What happens if you enter 26 in the Pressure Ratio field?

I just found a small review, and they weren't all that complimentary about the forced induction side of the program, but they liked the naturally aspirated side of it....


"However, we did input the data for a well-known single turbo engine (the program won't accept twin turbos) and the power and torque graphs were fairly close to the manufacturer's specs for this engine. However, there was almost no power gain at all when boost was then lifted - a patent absurdity to those who know factory turbo cars. The program having lost credibility in this area, I did not experiment further with forced induction engines.

Conclusion
Costing just US$54.95, we think that the Dyno2000 package is excellent value for money. On naturally aspirated engines, especially when cam changes are being considered, the results are consistent and accurate. The Iterative Testing feature (apparently a first for cost-effective engine simulation software) works well, and the results achieved on all naturally aspirated engines appeared to be very close to the mark. However, we think that the forced induction side of the program leaves something to be desired."

Thanks again,
Craig

[Andy Dunn]

they don't call him 750HP for nothing



I cheated a little and pushed the manifold to 1000 to bump the 750 line and this probably compensates for the weaker blower choice. Looks like you are right on target. I find dyno2000 to be accurate and is easily within 10% of real world dynos. It often gets within 5% which is pretty slick.

Andy

[750hp]

Good one! 750 it it then! Glad I din't have to change my member name down to 680hp or something! OK, one last thing.... without going to the trouble of uploading the graph or anything, could you tell me where the power level goes if you change the blower speed to 63000. I just worked out my impeller rpm @ max rpm, and that's what came up.

Thanks!!!!
Craig

[Andy Dunn]

for some reason, as the blower speed increases, it is dropping the graphs down in numbers.

At 63000

HP PEAK 667 @ 6500
TQ PEAK 618 @ 4500

so other things seem to be ocuring at the same time.

[750hp]

Thanks a heap Andy - it looks like you could spend hours changing one spec at a time on a "theoretical" engine build! I must admit, I like your the 750C.Gif chart the best

I'll try to think what the problem is with the blower rpm, and I might have to add the Dyno 2000 program to my shopping list when I come over for the fling.

BTW - Hurry up and get your car up and running again - I need my Butcher Story fix!!! Thanks for an entertaining and informative website!

[Jack21]

Dyno2000 is available direct from motionperformance.com for about $50 US. As you can see, it's invaluable for doing side-by-side comparisons, engine configurations, abd playing what-if with different combinations. summitracing.com has it, as well as virtually any speed shop, even in Australia.

[Andy Dunn]

Originally posted by 750hp
Hurry up and get your car up and running again - I need my Butcher Story fix!!!

thanks for the kind words 750hp, I have great news...this just in

http://www.cobralads.com/HOC-fires383/butcher42.html

Wooo Hooooo!






Andy
http://www.cobralads.com