Who's Running 26" & Smaller Drag Radials?

[PowerWagon896]

I have heard that this gives a good boost in ET reductions and I can understand why.

I would like to try some 275/40R17 BFGs for the effective gear reduction the 25.7" diameter will yield. Until 3.10-3.23 axle gears become available, this should be a good "stopgap measure".

However, some have reported problems W/HAL when doing this.

Will an ESP mod that involves disabling BAS/ESP eliminate the problems?

[RobAGD]

It should.

I pull fuse 17 to kill it in my 05 Magnum

Depending on your build date you dont have a fuse 17

Your GSM mod should kill it.

PS raised shift points I am crossing the line at 5600 ish rpms

-R

[PowerWagon896]

I was hoping you would chime in Rob.

It should.

I pull fuse 17 to kill it in my 05 Magnum

Depending on your build date you dont have a fuse 17

Your GSM mod should kill it.

No, the fuse 17 trick doesn't work on mine. I don't have the $200 GSM mod, but I think my $5 ESP mod will do the same thing. It's basicly the same thing I think, a normally closed relay inserted in the wire @ pin #22.

PS raised shift points I am crossing the line at 5600 ish rpms

I am a bit concerned as I think I will be getting close to running out of gear in 3rd @ 6100 RPM.

What is the diameter of your DRs & what was the MPH @ 5600 RPM?

Since I installed Hemi31s stock SRT cat-back I am hitting mid to high 106 MPH in the traps.

-R

Thanks

[PaCharger]

Here's what I just did:

Okay, Here is what I've found:

Michelin Pilot 235/55/18 - my stock tire
Width 9.25"
Sidewall height 5.09"
Overall height 28.18"
Circumference 88.52"

BFG T/A - my new Drag Radials...yeeeehaw
265/40/18
Width 10.43"
sidewall height 4.17"
Overall height 26.35"
Circumference 82.77"

Difference's
Width - BFG by 1.18"
sidewall Height - Michelin by .92"
overall height - michelin by 1.83"
Circumference - Michelin by 5.75"

My calculations are that the 2.82 rear will act like a 3.02 sized rear.
There is a 6.95% odometer reading as well.
Should put my 3rd gear ratio at 4.25...
So...If I can hit the traps above 4500-4600 like I do now, and instead, get closer to 5300-5700, I should see some serious improvements

[RobAGD]

Dan - i am hitting 104 at the traps

-R

[Hemi31]

The GSM mod or your custom one will keep you from having issues with the shorter DR's.You will get a little more gear,but before you go buy them I'd see if I could try someone elses.

[BrilliantBlackHemi]

The GSM mod or your custom one will keep you from having issues with the shorter DR's.You will get a little more gear,but before you go buy them I'd see if I could try someone elses.

Is that necesary if Powerwagon and Rob_AGD and you and I have all tried the 26 inchers and have confirmed a GSM type switch makes it allright to run them. The only negative I saw was I slowed down on the MPH, but the 60 ft and ETs were better and more consistent.

What I'm not sure is what running 26 inchers does on a SRT8.

[Hemi31]

Is that necesary if Powerwagon and Rob_AGD and you and I have all tried the 26 inchers and have confirmed a GSM type switch makes it allright to run them. The only negative I saw was I slowed down on the MPH, but the 60 ft and ETs were better and more consistent.

What I'm not sure is what running 26 inchers does on a SRT8.Powerwagon has not tried the 26" tires yet.His are 28".Thats why I said that.He may find his trap speeds lower.

[MadCharger]

Hey Power - did you ever get dyno numbers for your setup??

Sorry for the off subject post.......

[PowerWagon896]

The GSM mod or your custom one will keep you from having issues with the shorter DR's.You will get a little more gear,but before you go buy them I'd see if I could try someone elses.

I am going to get the cheaper black powder coated Crager "Soft" wheels ($59.95 ea) I will then have 2 complete set-ups to compare ET/MPH with.

Dan - i am hitting 104 at the traps

-R

Which DRS do you have? Are they 26" or are they less? The 1s I am considering, BFG DR2 275/40R17, are 25.7"

Is that necesary if Powerwagon and Rob_AGD and you and I have all tried the 26 inchers and have confirmed a GSM type switch makes it allright to run them. The only negative I saw was I slowed down on the MPH, but the 60 ft and ETs were better and more consistent.

What I'm not sure is what running 26 inchers does on a SRT8.

The combo I am considering is 25.7" in diameter. Compared to a stock 28 1/2" tire that will raise the effective FDR on an R/T to the same as 3.13 axle gears. (4.41:1 FDR in 3rd gear)

On an SRT it will raise the effective FDR to that of a 3.39 axle ratio. (4.78:1 FDR in 3rd gear)

IMO an SRT might be better suited to the 28" M&H DRs, you would run out of gear W/the shorter DRs in 3rd gear & not gain much, perhaps lose time on the additional shift. The 28" DRs would raise your effective FDR to that of a 3.12 axle gear. (4.39 FDR in 3rd)

Powerwagon has not tried the 26" tires yet.His are 28".Thats why I said that.He may find his trap speeds lower.

Actually Erik, if I get my 6.1 manifold on & the bugs worked out, along W/your old exhaust & the Frankentake III CAI, don't think it would hurt my trap speeds. It will be nice to compare the 2 set-ups on the same car/track/conditions.

Hey Power - did you ever get dyno numbers for your setup??

Sorry for the off subject post.......

That's OK. The #s were on a mustang Dyno and were by my estimation about 15% low compared to Dynotech # we have seen.

Evidence the fact that Erik's 12.7 second SRT only made 333 some RWHP. W/his track times I think 380 RWHP would be more realistic.

I did however make 90% of the HP that Erik made (298) W/the same TQ albeit @ a loweer RPM peak. So W/a conservative estimate of 380 RWHP for Erik's SRT, that puts me in the 340 RWHP range. About right considering my track times I think.

EDIT: I am planning on driving to the track W/the 28" M&H DRs on the car to make some base runs. After I switch to the 25.7" BFG DRs, any of you SRT (or R/T) owners that want to try the 28" combo, bring some steel wheel suitable lug nuts & I will let you try the M&Hs. (You can not use the stock lug nuts on the steel wheels if you want to re-use them on you alloy wheels. Been there, done that!)

[MadCharger]

That's OK. The #s were on a mustang Dyno and were by my estimation about 15% low compared to Dynotech # we have seen.

Evidence the fact that Erik's 12.7 second SRT only made 333 some RWHP. W/his track times I think 380 RWHP would be more realistic.

I did however make 90% of the HP that Erik made (298) W/the same TQ albeit @ a loweer RPM peak. So W/a conservative estimate of 380 RWHP for Erik's SRT, that puts me in the 340 RWHP range. About right considering my track times I think.


I always thought the Mustang dyno is a much more accurate dyno anyway, which is the one I'll be running mine on when I do. I'll be throwing the exact tire/wheel combo you're thinking of on mine next week, and let you know the difference just the tire size makes......