New Best w/ Cobra Jet testing

[86merc]

I made it out Sunday to get some runs in. The change from the previous best of 11.44 @ 116 was the cobra jet intake, scj mono blade throttle body, Kooks Super Street headers and a Spec stage 2 clutch. I did not get around to any weight reduction mods yet. The car with me in it weighed 3650# on the scale at the track. It had just under a half a tank of gas.

The trans still did not want to shift above 7200 on the 1-2. So I power shifted the 1-2 at 7,000 and the 2-3 at 7,700. With the shifting issues I didn't power shift the 3-4 so slow shifted at 7,700. The car picked up 3 mph over the stock intake. I think it has another couple tenths in it once I get it dialed in as is. If I can figure out the trans I see it picking up even more. I really do not want to spend the money on a Magnun XL. lol

I was mainly pleased that I was able to get the 60' times back in the 1.54-1,55 range on a 'ok' prepped track with the CJ intake. That was at a 6,600 rpm launch. On a good prep track and higher rpm launch I think it will go 1.52-1.53 as it sits. Then hopefully I can remove some weight. I may switch to a 3.90 gear as it would be more ideal for this intake. Sadly we only have tracks open around us for another week or so. Depending on the weather. I hope I can get back out testing at least one or two times yet.


DA +529

 

[EJR]

Great results. However i had the same shifting issues. Rebuilt the trans and put a mcleod RST in it. Effortless shifting at 8k rpm on the 1-2 shift. You may have already tired out the synchros from using the stock clutch. You definately dont need a Magnum XL. Also what are you running for gear? 3.73s?

 

[86merc]

Thanks. I talked to the dealership a while back. They are going to rebuild the trans as it howls real loud and admitted it probably will need syncros as well. They will take care of it I am sure. I hope it works out come spring. Because I don't want to spend that kind of money on a trans. lol

 

[EJR]

Yea its not necessary. Ive been through mine. Most people dont know that the gears are gigantic, synchros are carbon, and forks are very beefy. I replaced all my synchros front to back with new OEM ones, along with a set of bronze fork pads. I also made a steel shift stop to replace the factory plastic tipped one. Favorite manual trans ive ever driven.

 

[ExTurbo]

damn thats flyin, strong 60' , thats on the stock clutch? im surprised the MPH isnt a bit higher

 

[JUIC3D]

So the changes were intake, throttle body, and headers and you picked up 3mph? Did I read the write-up correctly? Or was the only change for this outing the intake?

 

[86merc]

Yea its not necessary. Ive been through mine. Most people dont know that the gears are gigantic, synchros are carbon, and forks are very beefy. I replaced all my synchros front to back with new OEM ones, along with a set of bronze fork pads. I also made a steel shift stop to replace the factory plastic tipped one. Favorite manual trans ive ever driven.

I like the trans and gearing. I have said in many threads around here. Besides the T56, the mT82 is the best trans the production mustang has seen. The best trans available for the car? Of course not. But I don't worry about breaking it like if it was a T5 or 3650. lol I hope a rebuild helps out and things are smooth after that.

damn thats flyin, strong 60' , thats on the stock clutch? im surprised the MPH isnt a bit higher

I had been 1.54 on the stock clutch. I had a slave cylinder fail so decided to upgrade the clutch. Especially since people were having issues shifting at high RPM with the stock clutch. When it came out of the car it still looked great.

My mph has always seemed lower than other cars with the same ET range. Not sure if I am over spinning the motor, slicks are hiding ET or what else could be the issue.

So the changes were intake, throttle body, and headers and you picked up 3mph? Did I read the write-up correctly? Or was the only change for this outing the intake?

Stock intake went 11.44 @ 116 in slightly negative DA. I forgot that since that run I also removed the front sway bar and added a Steeda sway bar delete. With the Spec clutch I also added their lightened steel flywheel. I was expecting to see 120-121 mph this time out. When I can powershift all three gear changes I think there will be some more mph as well.

 

[ExTurbo]

I had been 1.54 on the stock clutch. I had a slave cylinder fail so decided to upgrade the clutch. Especially since people were having issues shifting at high RPM with the stock clutch. When it came out of the car it still looked great.

My mph has always seemed lower than other cars with the same ET range. Not sure if I am over spinning the motor, slicks are hiding ET or what else could be the issue.

Strange about the MPH, the ET is killer though either way, most people are concerned with that above everythng else ;-)

I doubt you are over spinning it with that CJ intake on there, since there are guys running to 8k (granted most of those guys are boss's with the different cams. Have you put it on a dyno to see if you are making power at 7700 or does it start to fall off? I suppose it could be a number of factors, is the track uphill at all? Did you have a headwind?

 

[86merc]

Yeah, I look at ET more than MPH for sure. But the MPH looks off to me. If I can find MPH I know I can translate that into a better ET. This is the fun part, finding ways to make the combo go faster.

There was a slight headwind. Nothing too crazy though. 5-6mph maybe? Track is level. Lots of debate as it looks down hill by sight for several reasons. But we verified it with GPS a couple years ago.

I looked at threads and saw most guys were shifting about 7,700 rpm so that is where I decided to shift at. But yesterday I looked at my dyno graph where I made data logs with my base tune. HP peaks around 6,600 and tapers off slightly after that. Torque falls off pretty good 5,500. So that is why I was thinking I might be spinning it too high. More passes and trying different shift points will tell the tale. I also will be on the dyno in a few days not that I have a tune revision. See what it looks like and tweak from there.

 

[Ratchet]

So just to make sure we get this right, you gained .07 seconds and 3mph from CJ intake, throttle body, longtubes, refined tune, new clutch, lighter flywheel, swaybar delete? Am I missing any other mods? How much coin was into that 3mph and .07 gain? I know you'll get some better times and mph at some point, but this is a lot of money for very minimal gains IMO. Good luck man, hope you get it sorted to the point that this route makes sense. :beer:

 

[86merc]

The headers are the replacement short style, not long tubes. But yes, the 11.37 is not a huge improvement over the 11.44. The 11.44 run wasn't my first pass with the stock intake combo and I was able to powershift gears with out any issue. I have not seen to many people on here running as well with a stock set up. That, I think, is a pretty stout baseline.

The 3 mph is a gain and I will take it. It is progress. The CJ intake really changes the powerband of the engine. It took 800 rpm more on the launch to get the 60' time back to where it was with the stock intake. That alone took 5 passes to prove. I am sure playing with shift points will take a few passes to figure out the most efficient way to get it down the track. Some guys have proven the CJ intake works well. I have no doubt it works. I just need more passes to figure it all out.

 

[Ultrakla$$ic]

I like the honesty and reporting of ALL these CJ threads. Variability is noted and thanks for posting.

 

[86merc]

I have nothing to hide and have no reason to lie. Would I have loved to run a 10.99 the first time out? Well of course. But I also know it doesn't work like that. haha I knew I would have to work at it just like any other combo. There is a reason everyone doesn't buy the same combo and run the exact same ET. Those who are willing to work at it will be rewarded. I, for one, am willing to work at it. And I will post about it as I go.

 

[UnleashedBeast]

Just curious, how much of the gain can we attribute to better air, now that fall is upon us?

 

[EJR]

What track are you racing at?

 

[86merc]

It depends. It isn't just the air temperature that matters. To get the Density Altitude you need the temp, humidity percentage and barometric pressure. So even a cool day with a high humidity can have a poor DA.

But this time of year you are likely to have a DA at or below sea level. That can really help a naturally aspirated motor perform well. The local tracks to me are actually about 780' above sea level. This time of year we can see a DA of -1,000' or more. So if you race in the summer and see a DA of 2,500' you can see a two or three tenth swing in your ET.

You can get weather info and calculate your DA here. You can correct your time slip to sea level on that site as well.

 

[86merc]

What track are you racing at?

This was at Byron Dragway in Illinois. We also race quite a bit at Great Lakes Dragway in Wisconsin.

 

[Mike Rousch]

Those are great times to start with, As you said just keep working at it and it will come along!

 

[Shaun@AED]

I too love the MT-82
Customers who have swapped out the stock clutch for a McLeod twin disc have reported no more high RPM shifting issues.

 

[86merc]

Those are great times to start with, As you said just keep working at it and it will come along!

I think it is a good start. I am confident I will get the ET down. Just need more testing and tuning.

I too love the MT-82
Customers who have swapped out the stock clutch for a McLeod twin disc have reported no more high RPM shifting issues.

Yeah, I have heard that with other clutches as well. It could be me as it is only the 1-2 shift I had issues power shifting above 7,200. The 1-2 shift is one I never miss though. That is what make it so frustrating. The 2-3 powershift was smooth as can be. I guess we will see what happens after a trans rebuild this winter. Later this week I also plan to throw a whiteline shifter mount bushing in the car to see if that helps. Just frustrating more than anything.

I will also send you the data logs when I get it in the dyno later this week. Thanks for the help. :beer: