BDR chassis dyno/side pipe test

[native1]

Tomorrow I have an appointment to chassis dyno my BDR again. As you all can see in march of this year it went 449rwhp/434rwtq. Tomorrows test will be done on a different dyno and of course it is a lot more humid and a lot hotter, so we shall see. The only other difference is a change of gear ratio from 3.46 to 3.64s. The reason for the test is because my new mufflers will be in on Wed. and I will be replacing my stock ones with new stainless 3in. straight throughs.We all know the stock bdr muffs are very restrictive, so I will offer us some real numbers to ponder. Stainless Specialties made them for me and I must say they were very professional and quick. A local guy will be welding them up. It will take few days before I can retest the new side pipes, but it will be on the same dyno. I will also test the difference between the stock Roush oval air filter and the 14 inch K&N Extreme with the air inlets on the top. Tomorrow I will post the results of the air cleaner test. Next week the new pipes will be done and I will return to the dyno, will post new numbers asap. Hope what I learn will help us all make future decisions.

[Rwillia4]

looking forward to your results and getting to the 500 mark

[COBRANIP]

Also looking forward to seeing your results. With regards to differences in temp and humidity (and barometric pressure), the dyno software should "adjust" the results to a "standard" so your runs should be (somewhat) comparable. THANKS FOR SHARING!

[madmaxx]

449rwhp/434rwtq

That is impressive the sr/tw has about 520/520 at the flywheel. It will be interesting to see the results also!!!

[native1]

Ok here are todays results. I am very pleased with the numbers. There must be a difference in dynos. The only difference with the car since the last test is the rear end ratio and the addition of an electric fuel pump with no mechanical pump. The software (dynojet research) is the same on both dynos. Surprisingly, todays air temp was 98 F and back in March it was 79 F. Alright here goes. As you all can see it went 449rwhp/434twtq in march. Today we made 4 pulls...
1st pull 457rwhp/434rwtq 10.5air/fuel
2nd pull 461rwhp/434tq 12.5 air/fuel (made a jet change to lean out)
3rd pull 461rwhp/434tq 12.5 air/fuel (made change to air bleeds helped low end)
4th pull 467rwhp/436tq 12.8 air/fuel (changed air filter only)
Wow!!! 6rwhp for air filter alone!!!! Will remove side pipes tonight and take to welder tomorrow. I will post new dyno #s when I get them back. Maybe 1 or 2 weeks. I will be using the same dyno and I will not touch the engine. These numbers are legit and hopefully we can all see what the new muffs will really do. Next is custom headers.
I love these cars 2400 lbs 467rwhp AWSOME!!!

[native1]

Originally Posted by madmaxx

449rwhp/434rwtq

That is impressive the sr/tw has about 520/520 at the flywheel. It will be interesting to see the results also!!!

The only difference in my Roush 427 srtw is a vic jr. intake and a 950 cfm Holley 4150 dp. Both dyno pulls were done with these modifications. I am pleasently surprised at the Roush/Bdr numbers. Hopefully, side pipes and then custom headers will get me close to 500.

[greg schroeder]

That's pretty good.

Usually dyno numbers can be corrected to a given standard using an SAE formula. This way each day regardless of conditions you can compare apples to apples.

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

[Doug I]

467 .. yeah I guess that's just about close enough to be almost sufficient

That should keep the $100 on the dash pretty safe

460 at the wheels .... yup she'll squeal - hunker down - and scoot for sure !!

Could be a few extra ponies on tap if you drop the air-filter all together and put a grill to stop birds and rocks getting sucked in.

Custom headers ... 1-3/4 or 1-7/8" ?

[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.

[native1]

Custom headers ... 1-3/4 or 1-7/8" ?[/quote]

1-7/8 for the new ones, it has 1-3/4 now. The key I think,is the new header flange/ reversion plates. Stock bolt pattern is awful restrictive.

[native1]

Just thought you all might want to know. When the engine came from Roush the dyno tag on the 427 srtw read 510hp/528tq out of the crate. Then I put on the vic jr. and the 950cfm carb. Don't know were crankshaft hp is now. With the latest rwhp numbers, I would like to think it is around 540hp. I am very happy with the srtw, it pulls down low and up high.

[JayBar]

Originally Posted by native1

Just thought you all might want to know. When the engine came from Roush the dyno tag on the 427 srtw read 510hp/528tq out of the crate. Then I put on the vic jr. and the 950cfm carb. Don't know were crankshaft hp is now. With the latest rwhp numbers, I would like to think it is around 540hp. I am very happy with the srtw, it pulls down low and up high.

I have a Dart block locally built 408 with AFR heads H beam rods forged steel crank, tirck flow stage III cam. Petty much the same as a Roush but a lot less money. Anyway I dyno'ed at 401 hp at the rear wheels with a dual plane manifold with a HP 750 carb. My engine builder said if I really wanted to make some power I should go with a Victor Jr and a HP 950 carb. I did and gained 25 RWHP.
So your estimate of picking up 30 hp at the crank with the manifold and carb are right on.
Yea I know there are people out there saying I have over carb'ed it. But, you know what? It pulls like fuel injection. I can be lugging along at 35mph in 4th gear (3.73rear) and punch it, and it pulls no hesitation, just pulls.
I would not have believed it but I thought I would try it and it worked. Down side is 10mpg, but for the amount I drive it on the street it doesn't matter.

[Mark Brye]

I took my car to the dyno last week after installing SS mufflers last year. Before the side pipes, it made 420/420 or there abouts. I had to go to a different dyno jet after the sidepipe. Results from the different dynojet 390/390. The tune is still spot on. I know the car makes way more power with the new SS muflers so I will have to get back to the original dyno jet in order to get an apples to apples comparison.

[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.