BDR chassis dyno/side pipe test

[native1]

Originally Posted by greg schroeder

That's pretty good.



You should take that car to the drag strip. I bet you would do really good for trap speed.

Greg your car is very fast what is your rwhp/rwtq. If I could run that fast it would be sweeeet. Only have 1/8 mile here. I really want 1/4 mile.

[greg schroeder]

Originally Posted by native1

Greg your car is very fast what is your rwhp/rwtq. If I could run that fast it would be sweeeet. Only have 1/8 mile here. I really want 1/4 mile.

Get some Mickey Thompson ET street drag radials in the 275/60 15, run 20-22psi. It's the best performance mod for street driving you can do. Your HP would put you in the 10s easy with a 1.7 60ft or better on a cool day in VA. Just start from idle and nail it. You don't need to break stuff on the start. MPH tells the real story anyway. Once you get your 60ft time you can always go back and figure 1/4 time potential.

I went through pretty much the same routine as your engine set up, but I started with a Victor Jr intake as it came on the 427R. I put on a larger size fuel line and kept the mechanical pump, good fuel filter, different 3" core side pipes, 2" primary headers, Pro-Systems carb(a bit over 1000 cfm), more surface on air filter. I'm at 475 rear wheel and a huge wide torque curve at about 460. That's corrected with the standard SAE deal. Any respectable shop is going to use a corrected SAE formula from one day to the next so the results are comparable. I'm sure your shop did the same. Usually the dyno sheet says right on it stuff like the corrected factor to make alike comparisons, conditions of air and stuff like how much smoothing they used to make the graph look nice. Zero or 0 smoothing would be the nice for analyzing things. The air fuel ratio is a big factor too and pretty critical to have.

If you go from one day to the next with the same jets in a carb and exact set up, but different weather the car is going to be better one of those days because of the air fuel ratio. It sounds like you're probably getting better flow with those pipes. Being that the weather was warmer you need less fuel for the air, but being that the pipes probably move a bit more air it sort of balanced out. If you had your air fuel ratio graph that would help quite a bit to answer things.

Unrelated to the dyno, but another thing is Cobras have pretty bad coefficient of drag and a huge drag of resistance if say over 100 mph. The faster you go the leaner the jetting becomes if the car is really moving. I calculated out about 130 HP to push the car around 115 mph. It's stuff to think about depending on the purpose of the car. 1/4 mile drag racing gives the engine a short time in 4th gear were it would be most lean, but you want that air fuel sufficient for the safety of the engine. An air fuel from a 4th gear Dynojet pull might be pretty good for drag race tuning. I'm sure there are many variables.

I'd be really interested to see your SRTW with Victor Jr. intake dyno sheet to see the torque range and power curve vs. the 427R-095. Then again we have different exhaust, so the comparison is sort of mixed. I did get a wider torque curve with the Buckshot Racefab side pipes. Roush runs 2" primary headers and open end collectors for their engine test, or at least that's what they told me when I asked.

[FUNFER2]

Just a note.
There is a big difference between the "Dyno-jet" and the "Mustang" dyno. It varies from 50-80 + hp. If you want a bragging rights number, go with the Dyno-jet. If "real" numbers are wanted, use the Mustang.
Is 563 rwhp too much,........

Native1- you can't be more correct, I love these car's too.
HP & weight= fast fun !

[greg schroeder]

Originally Posted by FUNFER2

Just a note.
There is a big difference between the "Dyno-jet" and the "Mustang" dyno. It varies from 50-80 + hp. If you want a bragging rights number, go with the Dyno-jet. If "real" numbers are wanted, use the Mustang.
Is 563 rwhp too much,........

Native1- you can't be more correct, I love these car's too.
HP & weight= fast fun !

563 rwhp is a good number if you have the proof of that Cobra that traps over 140 mph at the drag strip. That would be cool. Usually from what I've noticed on Club Cobra 427 big blocks have trap speeds to support a couple hundred less HP at the wheels though. Your car must be pretty hot. Have you had it to the drag strip?

I think each type of dyno has good purpose. Something I like about the Dynojet is you get a number and it's darn near exact to trap speed at the drag strip after you plug it back into HP calculators. Mustang dynos have their place too.

[native1]

Finally back from the welder and then the dyno.. I must say I am little confused by the results. The pipes sound much better, a lot deeper but not much louder. Stainless specialities made the muffs and they were very nicely done. 3 inch straight through polished stainless 4 inch O.D. Heres were I get confused, my last dyno printout showed 467rwhp however the owner of the dyno said that convertd to 454rwhp. I don't know what the heck he is talking about but I guess that means it really made 454rwhp two weeks ago not 467. Maybe some of you guys can shed some light on these different software conversions???? Anyway, the new non converted HP is 461rwhp and 449rwtq. That means the new pipes made 7hp and 15fptq more. I was hoping for more considering this project cost 1000$ The carb fuel/air mix remained the same @ 12.9. The MPH @ 6200 was 130mph. I will post all different dyno printouts that I have, Maybe some of you guys can make sense of it all. So what's with the different conversions?? I was excited at 467 now I guess its really 461 but actually more HP. I don't get it?? I think the new headers will really help out. Will be a few months for those. Anyway the sound alone makes it all worth it but my goal of 500rwhp is going to hard to obtain without a little more help.

[greg schroeder]

Originally Posted by native1

Finally back from the welder and then the dyno.. I must say I am little confused by the results. The pipes sound much better, a lot deeper but not much louder. Stainless specialities made the muffs and they were very nicely done. 3 inch straight through polished stainless 4 inch O.D. Heres were I get confused, my last dyno printout showed 467rwhp however the owner of the dyno said that convertd to 454rwhp. I don't know what the heck he is talking about but I guess that means it really made 454rwhp two weeks ago not 467. Maybe some of you guys can shed some light on these different software conversions???? Anyway, the new non converted HP is 461rwhp and 449rwtq. That means the new pipes made 7hp and 15fptq more. I was hoping for more considering this project cost 1000$ The carb fuel/air mix remained the same @ 12.9. The MPH @ 6200 was 130mph. I will post all different dyno printouts that I have, Maybe some of you guys can make sense of it all. So what's with the different conversions?? I was excited at 467 now I guess its really 461 but actually more HP. I don't get it?? I think the new headers will really help out. Will be a few months for those. Anyway the sound alone makes it all worth it but my goal of 500rwhp is going to hard to obtain without a little more help.

The numbers corrected when done on the same dyno would be most relevant. There are different correction factors. There are even 1/4 mile sea level correction calculators. The purpose is to put different condition testing of the same type into alike comparison. Cooler, drier air with more pressure makes the most power. Warmer, wetter air with lower pressure makes less power. Corrected numbers correct the values to a given standard, so you're comparing apples to apples.

As an example it wouldn't do much good to use uncorrected numbers and test a car on a 100F day with 60F dew point and 29.7 on the barometer then change the air cleaner and do the same test on a 27F day with 15F dew point and a 30.3 on the barometer then conclude the air cleaner produced 60 wheel HP. It happens, but it's just an invalid test.

A really good test for usable power in my opinion is 1/4 mile trap speed. I know guys with all sorts of hot street cars in the 300 to 1500 wheel HP range and trap speeds are really close to Dynojets. From there it's possible to correct to sea level with this calculator. I really like this method of 1/4 mile trap speed because it's reality.

http://www.modulardepot.com/density.php

Whatever test that's uses it's important to keep it consistent and look at change rather than the numbers.

This link is pretty good.

http://wahiduddin.net/calc/cf.htm

Your headers probably cover your exhaust ports right now. Those that came with my Superformance covered about 1/3 inch of width on each exhaust port. The new headers only added a bit, but seemed to give the top end a little push.