BOG problem with 17 in. ET Streets!!!
Thread Starter
Teching In
Joined: Sep 2004
Posts: 8
Likes: 0
From: DFW
BOG problem with 17 in. ET Streets!!! With 4.10 gears (8.8 Ford) on 17 in. ET Streets mounted on 17x9 in. rims launching at 5500 rpm I am bogging.
[02 M6 Z28, lid, y-pipe, catback, 329 HP]
I had the opposite problem with BFG DRs and the stock flywheel - bad wheelspin at any launch above about 4000 rpm.
I have done lots of searches and also posted in the New Owner section, and it was suggested that I post in this forum.
Here is the scenario:
Went to 4.10s to help the bog I had with 3.73s. Started hitting the rev limiter (stock 6200) at the end of the 1/8th with the 4.10s. I went to bigger tires to solve the rev limiter problem. The ET Streets are advertised on the MT website to be 26.5 in. tall on 9 in. rims. However, the ET Streets are actually 27.75 in. and have basically brought me back to 3.80s because of the height. I also put an aluminum flywheel when I got the Spec 3 clutch when I still had 3.73s.
Is THE BOG due to:
1. Aluminum flywheel?
2. Tall tires?
3. Both?
I would appreciate any suggestions. Thanks in adavance.
[02 M6 Z28, lid, y-pipe, catback, 329 HP]
I had the opposite problem with BFG DRs and the stock flywheel - bad wheelspin at any launch above about 4000 rpm.
I have done lots of searches and also posted in the New Owner section, and it was suggested that I post in this forum.
Here is the scenario:
Went to 4.10s to help the bog I had with 3.73s. Started hitting the rev limiter (stock 6200) at the end of the 1/8th with the 4.10s. I went to bigger tires to solve the rev limiter problem. The ET Streets are advertised on the MT website to be 26.5 in. tall on 9 in. rims. However, the ET Streets are actually 27.75 in. and have basically brought me back to 3.80s because of the height. I also put an aluminum flywheel when I got the Spec 3 clutch when I still had 3.73s.
Is THE BOG due to:
1. Aluminum flywheel?
2. Tall tires?
3. Both?
I would appreciate any suggestions. Thanks in adavance.
Your flywheel is more for Road Racing applications, where the rotating mass needs to be minimized to allow the engine to vary rpms with less parasitic drag of heavier components. In drag racing, this is the opposite ... you need the additional weight in the flywheel to keep the rpms in the higher rpm range. The additional weight helps to keep the rpms up there on initial launch, it is much harder to drag down the rpms with a higher rotational mass.
What size were the BFGs? On what size rim? What size ET Street are you running now? It could be the combination of both, if the weather conditions are very similar with both setups.
What size were the BFGs? On what size rim? What size ET Street are you running now? It could be the combination of both, if the weather conditions are very similar with both setups.
TECH Regular
Joined: Aug 2003
Posts: 453
Likes: 0
Probably the flywheel - try more RPM's on the launch until you can change the flywheel back!
Those 17" ET's should only be 26" tall - MT's are a little oversized, but not 2"! Measure them while on the car and aired down - from the center of the wheel to the ground, then multipy X 2 to get the "as used" size.
Al
Those 17" ET's should only be 26" tall - MT's are a little oversized, but not 2"! Measure them while on the car and aired down - from the center of the wheel to the ground, then multipy X 2 to get the "as used" size.
Al
Last edited by T6Rocket; Oct 5, 2004 at 11:59 AM.
Thread Starter
Teching In
Joined: Sep 2004
Posts: 8
Likes: 0
From: DFW
Originally Posted by 12secSS
What size were the BFGs? On what size rim? What size ET Street are you running now? It could be the combination of both, if the weather conditions are very similar with both setups.
The ET Streets are the only 17" available, which is 26x11.50x17 on the same 9" rim. The MT website says they are 26.5" tall on a 9" rim, which would have been perfect. We measured them at 27.75" tall! I called MT Tech Support and he said that the web site was wrong, that they are 26.5" tall on an 11" rim and that they would be much taller on a 9" rim. Yeah, thanks. MT - I already knew that.
Anyway, thanks for the input, 12secSS.
Thread Starter
Teching In
Joined: Sep 2004
Posts: 8
Likes: 0
From: DFW
Originally Posted by T6Rocket
Probably the flywheel - try more RPM's on the launch until you can change the flywheel back!
Those 17" ET's should only be 26" tall - MT's are a little oversized, but not 2"! Measure them while on the car and aired down - from the center of the wheel to the ground, then multipy X 2 to get the "as used" size.
Al
Those 17" ET's should only be 26" tall - MT's are a little oversized, but not 2"! Measure them while on the car and aired down - from the center of the wheel to the ground, then multipy X 2 to get the "as used" size.
Al
See my explanation above where I called MT. We now find out that we need an 11" rim. I'm hearing more and more to go back to the heavy flywheel. Thanks for the input.
Trending Topics
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine
Verdad Gallardo
7 Most Reliable High-Performance Engines GM Has Ever Built
Verdad Gallardo
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin
Verdad Gallardo
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo Try a little more air. Go up 1/2 to 1lb for each run don't change anything else. One of my buds around here goes 1.6x-1.7x on drag radials and he has an aluminum flywheel (
(m6). But on the other hand he has a procharger, that's a bit different than your situation. I myself have not been able to come close to that on drag radials. I am h/c.
(m6). But on the other hand he has a procharger, that's a bit different than your situation. I myself have not been able to come close to that on drag radials. I am h/c.
TECH Regular
Joined: Aug 2003
Posts: 453
Likes: 0
If you put the ET Street side by side with the BFG, it will look a lot taller b/c the tread area bulges out. When the weight of the car is on it, it flattens out.
I wouldnt waste money on an 11" rim - it is not going to change the height of the tire. Wider rim can only change the contact patch.
Al
I wouldnt waste money on an 11" rim - it is not going to change the height of the tire. Wider rim can only change the contact patch.
Al
I had a burnt clutch, every launch with my Nitto's at 18 p.s.i. resulted in a bog. I found the best way to correct the bog until I could correct my clutch issue was to run the tires at 20 - 22 p.s.i. Sure, I spun a little more but the car didnt bog.
Try increasing the tire pressure, it'll let the tires spin and keep you from dead hooking/bogging.
Try increasing the tire pressure, it'll let the tires spin and keep you from dead hooking/bogging.
Originally Posted by lisaz28
BFGs were 275x40x17 on a 9" rim. Specs say there are 25.7" tall and we measured them at 25.75".
The ET Streets are the only 17" available, which is 26x11.50x17 on the same 9" rim. The MT website says they are 26.5" tall on a 9" rim, which would have been perfect. We measured them at 27.75" tall! I called MT Tech Support and he said that the web site was wrong, that they are 26.5" tall on an 11" rim and that they would be much taller on a 9" rim. Yeah, thanks. MT - I already knew that.
Anyway, thanks for the input, 12secSS.
The ET Streets are the only 17" available, which is 26x11.50x17 on the same 9" rim. The MT website says they are 26.5" tall on a 9" rim, which would have been perfect. We measured them at 27.75" tall! I called MT Tech Support and he said that the web site was wrong, that they are 26.5" tall on an 11" rim and that they would be much taller on a 9" rim. Yeah, thanks. MT - I already knew that.
Anyway, thanks for the input, 12secSS.
That tire size difference isn't enough to cause a bogging problem in my opinion. Another question ... what PSI are you running in your tires? These guys bring up an interesting point about tire pressure that I didn't think about. My wife has run on ET Streets (26x10.5x15) at 30psi once and retained her mid-low 1.6 60' times. Could be your tire pressure is too low. The rule of thumb is to run as much PSI in your tires without losing traction. This helps keep your top-end mph. Running too low of a PSI is not a good idea. Just thought I would suggest another option for you, could be the track you race at is a very good hooking track and you don't need to air down your tires. 
Good luck! 