Chassis Dyno- eye opening!

[fryedaddy]

i guess a lot of it,on the chassis dyno and drag strip numbers has a lot to do with how well you have your car  set up .i have a friend with a very mild engine in his drag car.he runs numbers that most people would need 100 more hp to match.he is one of those guys who can get everything out of what he has to work with.jmo,   brian

[jgkurz]

Do those numbers indicate a breathing problem? Wondering if 2.5” exhaust was a huge compromise

I recently put my 69 Mustang on a chassis dyno and lost 23% at the wheels as compared to a SuperFlow engine dyno. I had open headers on the engine dyno and full 3" Magnaflow exhaust on the chassis dyno. All I can say is that 2.5" exhaust will be more restrictive than 3" but it might not matter until an engine is over a certain HP. I have seen/heard many opinions on the benefit threshold from 2.5" to 3". Most say above 500hp. My personal thought is that your engine might put down a bit more HP with 3" but the installation hassle, drone, and extra decibels may not be worth it until 3" will provide a sizeable gain. By the way, my car is very LOUD even with full 3" exhaust. It would be quieter with 2.5"

Regarding drivetrain loss, I have automatic which probably doesn't help. Maybe it's no worse than the TKO600. Hard to know. I will always dyno the car at the same location so I can compare when I make changes.  The place I went to mostly does Toyota's so an FE set on kill was a new experience for them. Ha!

I was on a new DynoJet 424xLC. Just curious what brand you were on?

-John

[cammerfe]

In regard to noise, I put a full-length 3" stainless (321) exhaust system in my '63 Effie ICB/390-330, using Bassani 2 1/2 foot mufflers. I used '64 427 exhaust manifolds and went 3" from there back. Very Pleasant mellow tone.

KS

[Falcon67]

I can offer this about under hood/outside air.  Testing with a 500 HP 351C, underhood air regular 14" x 2" air cleaner vs tear drop hood, foam seal, 14x3" air cleaner - change was worth .3 and 3 MPH in the 1/8 on the drag strip.  Huuuuuge.

[scott foxwell]

There's a reason most (all, that I know of) HP and performance calculators refer to, and use, crankshaft HP.

[Falcon67]

i guess a lot of it,on the chassis dyno and drag strip numbers has a lot to do with how well you have your car  set up .i have a friend with a very mild engine in his drag car.he runs numbers that most people would need 100 more hp to match.he is one of those guys who can get everything out of what he has to work with.jmo,   brian

MPH vs weight is the best indicator.  ET means nothing about power.  ET changes with moon phase, sun spots, bad 60', day of the week, etc. 

[cjshaker]

ET changes with moon phase, sun spots, bad 60', day of the week, etc.

LOL! That certainly is true. My car has varied as much as  1.5 seconds as I've changed my style of launch, among other things. The 60' has varied by about as much, but the speed is always 114-115. It doesn't matter if I spin the first 60', killing the ET. You would think that a quicker launch and better 60' would mean that your trap speed would be higher since your car is getting a better 'start', but it just doesn't work that way.

[427HISS]

There are a lot of differences between manufactures of dyno's as well. My friend has two chassis dyno's and tells customers if you want bragging numbers get on the Dyno-Jet if you want real numbers get on the Mustang dyno. I hear some differences in engine dyno's. It's more about tuning than top power results.