26 inch MT vs 28 inch MT

[Texas gn]

Ok, question. I have a set of 255/50/16 (26 inch tire) Mt DRs on the back. I am capable of running 12.26 @ 112 mph with them. If I was to change to a 15” rim and run a (28 inch MT) how much should that help me at the end of the quarter? I was thinking of buying some of the wider original wheels.

 

[imjoesnuffy]

It would probably give you a slower ET, kill your 60 foot, you might trap higher though. I think the common idea is to move to a 28" inch tire when you trap over 120 mph.

Im still on a 255 tire running through the lights at 127, but I just bought some 275/60-15 MT ET streets. Have to wait till next month to see what I pick up if any.

 

[Texas gn]

Thanks, I was a little worried I was getting close to the red line at the end of the ¼ with my stock engine. I have just installed my PL and have yet been to the track. My Scanmaster was always set to KR and not RPMs and it sure is hard looking at the factory tack. Let me know how the 275s work out for ya.

 

[Raist103]

at 112 you are not even close to hitting the red line. 3rd gear stock is closer to 120-123

 

[scojack_2001]

I used to run that same tire and got a 11.48@115 out of my setup with them. I was/am running a few more pounds of boost though. My setup would run that on a 26" street tire on a soft launch.

I recently switched to a 275/60/15 MT DR on my 15" race wheels. I went from a 11.70 the first time out to a 11.32@118 the second time out. I put the tall tires on it and gave it timing in 1/2 and cranked the boost. I just fed it 93 & alchy and prayed it stayed together.

Pretty much a stock setup. Im assuming the engine is stock, but Ive never had the heads off of it.

Hope this helps.

 

[Texas gn]

I used to run that same tire and got a 11.48@115 out of my setup with them. I was/am running a few more pounds of boost though. My setup would run that on a 26" street tire on a soft launch.

I recently switched to a 275/60/15 MT DR on my 15" race wheels. I went from a 11.70 the first time out to a 11.32@118 the second time out. I put the tall tires on it and gave it timing in 1/2 and cranked the boost. I just fed it 93 & alchy and prayed it stayed together.

Pretty much a stock setup. Im assuming the engine is stock, but Ive never had the heads off of it.

Hope this helps.

Do you remember what your 60 ft. times were? And how many pounds of boost it was at? I fine you information very interesting because the times you are running is my goal (11.50s) and it sounds like we have similar stock setups. Sure would like to know more about your recipe! I have not played with my timing or fueling yet because I just finish installing powerlogger and the fuel pressure setup for the powerlogger. My best was a crappy 1.9 60ft at 2psi and I spun the tires for 6-7 feet. So I added air bags long shoes SS brake components. Now I can hold 8-10 lbs. on the line easy and the car likes 25psi. Now I am waiting for it to cool off some before I head back to the track…couple of weeks I hope.

 

[scojack_2001]

Do you remember what your 60 ft. times were? And how many pounds of boost it was at? I fine you information very interesting because the times you are running is my goal (11.50s) and it sounds like we have similar stock setups. Sure would like to know more about your recipe! I have not played with my timing or fueling yet because I just finish installing powerlogger and the fuel pressure setup for the powerlogger. My best was a crappy 1.9 60ft at 2psi and I spun the tires for 6-7 feet. So I added air bags long shoes SS brake components. Now I can hold 8-10 lbs. on the line easy and the car likes 25psi. Now I am waiting for it to cool off some before I head back to the track…couple of weeks I hope.

On the 11.32 pass, my 60' was a 1.601; and the tires did break loose a little bit, but hooked right back up. Boost was up there, it pegged my 3 bar MAP on the first pass. So I'm gonna guess it was somewhere in the neighborhood of 28-29 pounds... It helped that the track was well prepped and the air was good.

My car is a basic street/strip setup.

Stock motor w/125K, stock heads & cam, Comp 980 springs and Edelbrock double roller chain
200-4R out of my T-Type, mostly stock, CK shift kit & servo, Alto band and direct clutches, 10 vain pump, Art Carr pan and 700R4 filter. Stock DS with solid u joints.
TE-62 journal bearing w/ .63 A/R exhaust housing
Dutt neck IC
3" THDP with Hooker exhaust and a cutout
MSD50s, 340 pump, Accufab regulator, stock lines
PowerLogger and TT 5.6 alchy chip
all the other stuff too.

Rear suspension is mostly stock. Stock, fully boxed LCAs (w/ rubber bushings), original uppers, Kirban cargo coils, dual airbags, KYB GR-2 shocks. And a Full Throttle "ATR-style" rear swaybar. Big shoes and big cylinders in the rear brakes. I can hold 10psi+ on the vacuum brakes.

Its a full weight/full interior street car.

Hope this helps.

 

[Texas gn]

On the 11.32 pass, my 60' was a 1.601; and the tires did break loose a little bit, but hooked right back up. Boost was up there, it pegged my 3 bar MAP on the first pass. So I'm gonna guess it was somewhere in the neighborhood of 28-29 pounds... It helped that the track was well prepped and the air was good.

My car is a basic street/strip setup.

Stock motor w/125K, stock heads & cam, Comp 980 springs and Edelbrock double roller chain
200-4R out of my T-Type, mostly stock, CK shift kit & servo, Alto band and direct clutches, 10 vain pump, Art Carr pan and 700R4 filter. Stock DS with solid u joints.
TE-62 journal bearing w/ .63 A/R exhaust housing
Dutt neck IC
3" THDP with Hooker exhaust and a cutout
MSD50s, 340 pump, Accufab regulator, stock lines
PowerLogger and TT 5.6 alchy chip
all the other stuff too.

Rear suspension is mostly stock. Stock, fully boxed LCAs (w/ rubber bushings), original uppers, Kirban cargo coils, dual airbags, KYB GR-2 shocks. And a Full Throttle "ATR-style" rear swaybar. Big shoes and big cylinders in the rear brakes. I can hold 10psi+ on the vacuum brakes.

Its a full weight/full interior street car.

Hope this helps.

You nailed it! I have had thoughts of going to 30psi and just might do it as long as everything looks good. I do worry that the 23 year old head gaskets aren’t up to it or the original timing chain. My GN only has 31k on it now so they might take it. The one thing I didn’t see was your timing settings and fuel setting….my O2s (don’t have the WB yet) are in the 720s in 3rd WOT. Other then I have a TE-60 we are pretty close. I should be able to squeak out a high 11.7 …..Lot to learn! And thanks for your input

 

[scojack_2001]

You nailed it! I have had thoughts of going to 30psi and just might do it as long as everything looks good. I do worry that the 23 year old head gaskets aren’t up to it or the original timing chain. My GN only has 31k on it now so they might take it. The one thing I didn’t see was your timing settings and fuel setting….my O2s (don’t have the WB yet) are in the 720s in 3rd WOT. Other then I have a TE-60 we are pretty close. I should be able to squeak out a high 11.7 …..Lot to learn! And thanks for your input

Timing was up to +2.8° in 1/2 and I left the 3/4 alone at 21°. Fuel settings I didn't touch. Wideband said it was lean, but I knew I was on a good pass so I stayed in it. I usually go for 10.8-11.0 A/F on the alcohol.

 

[Texas gn]

Thanks, now i know what i want to target in my setting. I will start low and creep up to it. thanks again

 

[Dabigguy]

Subscribed !!!

 

[mr go fast]

28's on mine with stock rearend on stock GN wheels. I have received plenty of 1.6ish 60fts out of the gate. I have a fully loaded stock interior GN that has a race weight of 3950lbs with me in it. I trap 110mph. I to this day dont understand how people install 26's tall tires on a non lowered Gbody. Makes no sense to see all that wheel gap. I hope to be testing pretty soon with the upgraded TE44.