Standing 1 and 1.5 mile LSR

R

Rocketdog

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Joined
Sep 28, 2023
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Location
New Hampshire
Vehicle Details
1995 Mercury Cougar XR7 Restomod DOHC V8
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We plan to run this car at Loring this year. We have a lot to do, but I am within sight of sending the car to the Mac to have him install the 10 point cage. That milestone has been hard coming to.
I am putting together a list of "must have" items for procurement. I need the help of brother members in selecting the proper final drive.

I was under the impression LSR was all flying start. Wrong again. This course is 2.7 miles of taxiway with timing at 1 and 1.5 miles. The start is "standing", and the "go" command comes from the marshal.

Here is the "street" setup right now:
Tires: 27.9"
Final drive: 3.73:1
Traction Lock
Cast housing
10" 3800-4400rpm stall torque converter with anti-balloon plate
Force lubed, J-modded 4R70W
4" one piece aluminum shaft

I have the open 3.07 in the aluminum housing from my Mark donor car to work with.

My instinct tells me this is almost right for an NA DOHC car for the mile.

It's a stock gen 2 engine with a 25% UD harmonic and the Cougar's Ignition (speed coils). I have the IMRCs wired wide open and by then I should have long tubes on it. Even well tuned it's probably only 300-305hp.

With a flying start I would go open and long, like 2.73 or longer even. I am not seeing the car topping out in third gear inside a mile. If it does hit the limiter, I guess we could back off and let it have 4th gear. Seems a scary prospect to shift at that speed.
 
Sounds like a fun project and you've got a good plan. What speed are you going for?

Years ago Guitar Maestro sent me an excel spreadsheet 4R70W speed calculator based on gear ratios. He did all the math using his math brain so you know it's right. :ROFLMAO:

PM me your email address and I'll send you a copy if you're interested.
 
The car will shift into 4th at 127.5 MPH regardless of whether you have OD lockout on or off unless whoever tuned your PCM really knew what they were doing. With a 3.73 rear end, that would be about 5700 RPM in 3rd gear, assuming the proper 19 tooth speedo gear. Again, assuming a tune, chances are your WOT 3-4 is commanded after that RPM. You could let off the throttle to trigger the shift; if you let it try to shift a 3-4 at WOT, you will break the trans. Double and triple check with your tuner to find out if they fixed the 127.5 mph bug.

With a 2.73 rear end and a 14 tooth speedo gear. 127.5 MPH would hit at a paltry 4200 RPM in 3rd gear, so again - you WILL shift into 4th gear at that RPM, commanded in the tune or not. You can also cheat by using a speedo gear with more teeth than is needed for your rear end. This will underdrive the VSS and "trick" the PCM into thinking the car is going slower than it actually is. This is IMO a better way to get around this problem if your tuner can't guarantee a fix in the tune.

Considering most ~300 BHP MN12/FN10 combos will do high 13s 1/4 mile passes at around 100 MPH, it is very likely that you will exceed 127.5 over a 1-1.5 mile stretch. Aside from the upshift bug, you will want to avoid shifting into 4th if possible as 3rd gear is the most efficient in terms of power lost through the drivetrain. Set up your rear end to get you as close to your redline in 3rd as possible by the time you start to decelerate. The OD band will not like holding at WOT for any length of time either.

I created a JavaScript calculator with a focus on tires, but other stuff is in there as well. Play around if you like.

 
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Add a Carbon fiber OD band. make sure your trans is using one-piece teflon seals on the direct shaft.
If you don't check the tune, you will get what I had, 3-4, 4-3 about 1000 times really fast, and by the time you let off, you will have no 3rd or 4th.
 
Agreed that it's imperative that the tune is corrected to avoid a WOT shift into OD. That said, first time out, I'd try 2.73's with your combo.
 
With 1.5mi and 300hp, I suspect you should be up in the 140-145mph range. Peak hp in the MarkVIII is at 5700rpm, and with your tire size, 3.27s will put you at 146mph at 5700rpm in 3rd gear, so that is what I would start with. That will still give you a little headroom if you wind up going faster than that, since you could wind it out to 6000rpm which would give you 152mph. If you wind up going faster than that, you can drop the gear down to the 3.07s, which would give you 154mph at 5700rpm and 162mph at 6000rpm, but I think you’ll need significantly more hp to get up to those speeds.
 
According to calcs, a t =bird needs 400hp to reach 145 mph. A cougar more, .32 vs .38 cd, and the same frontal area.
 
Not sure what calculators those are, but I can tell you for sure they are wrong. I’ve hit 157mph in a mildly modded 89XR7, which I’m sure had less than 300hp. Hell I hit 138mph in my 97 bird with nothing but a 5-speed swap and a PI intake, and that wasn’t even a top speed run, was just trying to get away from someone who was screwing with me on the highway. 400hp is 03/04 Cobra territory, and those had worse aero than the MN12 and typically go 170mph with a tune to remove the factory 155mph speed limiter.
 
I used the simulator I use for rockets, and the data from sccoa; .32 cd from the datasheet and the 21.4 frontal area.

user1120_pic18432_1267488058.jpg
This is the formula, reconfigured for hp instead of newtons.
 
Grog6 said:
I used the simulator I use for rockets, and the data from sccoa; .32 cd from the datasheet and the 21.4 frontal area.

View attachment 9070
This is the formula, reconfigured for hp instead of newtons.
Click to expand...
Theory only gets you so far. That’s why they kill test pilots pushing the edge to find the true limit.
 
My god you guys know your shit. (sorry for the swearing) I know enough to keep my car running and even then I am at a loss sometimes.
 
White Lincoln said:
My god you guys know your shit. (sorry for the swearing) I know enough to keep my car running and even then I am at a loss sometimes.
Click to expand...
I know! These guys impress the crap out of me too. So thankful for the community here. We brain drained TF out of TSTSNBN. 😁
 
I was wondering how fast I reasonably could have gone on that last drive home during the pandemic, where I managed to drain all the oil out the pcv valve, lol.
Over about 3k rpm, oil stays in the pass head. You'd think it would spill over the front edge, but apparently, it gets to the pcv valve first. My oil seperator in that vacuum line was full, as was the intake manifold. There was no oil in the crankcase. I ran 5500 rpm in 4th most of the way home; the gps said 165 peak, and I seriously wondered if that's possible. I'm still unsure. Lazarus is PI cams, pi manifold, true duals, and a tune I wrote. Rev limit is at 5500, and I was bouncing off it most of the way home. I passed a trooper radaring, and he didn't even pull out.
I bought a gps after I wasted the stock speedo changing outthe gears. :roll:
 
Trunk Monkey said:
Sounds like a fun project and you've got a good plan. What speed are you going for?

Years ago Guitar Maestro sent me an excel spreadsheet 4R70W speed calculator based on gear ratios. He did all the math using his math brain so you know it's right. :ROFLMAO:

PM me your email address and I'll send you a copy if you're interested.
Click to expand...
Hey Man,
I hope all is well. Thanks for the reply.
We want to go Fast. We will go as fast as we can, within reason.
With this request I am trying to prevent ending up in Maine with the wrong gear set in the car.

After some thought, I am walking back a bit on this. I am of the opinion that the car will hit a 6k limiter inside 1 mile set up as I am.

I am going to reply in more detail to the excellent reply below.
For now, I have Jerry's white paper on the 4r70w, but if I need more I know where to go now,

RD
 
theterminator93 said:
The car will shift into 4th at 127.5 MPH regardless of whether you have OD lockout on or off unless whoever tuned your PCM really knew what they were doing. With a 3.73 rear end, that would be about 5700 RPM in 3rd gear, assuming the proper 19 tooth speedo gear. Again, assuming a tune, chances are your WOT 3-4 is commanded after that RPM. You could let off the throttle to trigger the shift; if you let it try to shift a 3-4 at WOT, you will break the trans. Double and triple check with your tuner to find out if they fixed the 127.5 mph bug.

With a 2.73 rear end and a 14 tooth speedo gear. 127.5 MPH would hit at a paltry 4200 RPM in 3rd gear, so again - you WILL shift into 4th gear at that RPM, commanded in the tune or not. You can also cheat by using a speedo gear with more teeth than is needed for your rear end. This will underdrive the VSS and "trick" the PCM into thinking the car is going slower than it actually is. This is IMO a better way to get around this problem if your tuner can't guarantee a fix in the tune.

Considering most ~300 BHP MN12/FN10 combos will do high 13s 1/4 mile passes at around 100 MPH, it is very likely that you will exceed 127.5 over a 1-1.5 mile stretch. Aside from the upshift bug, you will want to avoid shifting into 4th if possible as 3rd gear is the most efficient in terms of power lost through the drivetrain. Set up your rear end to get you as close to your redline in 3rd as possible by the time you start to decelerate. The OD band will not like holding at WOT for any length of time either.

I created a JavaScript calculator with a focus on tires, but other stuff is in there as well. Play around if you like.

Click to expand...

Terrmi,

Thanks for the reply.
I have been working with Lasota Racing on the PCM and tuning aspects of the venture. I held off until I was fairly confident I had a safe race car to work with, and we are getting there.
We have half the tuning books already and we are working with Don for a package on the Advantage software, a wideband sensor setup and a datalogger. My local Dyno shop knows Don and has indicated they like the arrangement and are willing to help locally in addition to Don remotely.

Consensus is to lock it out of fourth gear.
I thought about your comment regarding speedo ger teeth. I assume you are saying a 2.73 gear in a trans that was 3.08 would yield 12% speed increase from 127mph, or 142ish for a PCM commanded shift into OD regardless of rpm or indicated speed or speed limiter. I still think about it.

It seems that much attention was paid to ensuring a 3-4 shift gets done at reasonable shaft speeds by engineering. I choose not to second guess that, ballistic blanket or not. We are gonna run it in third.

I have my reservations about operating beyond the oem redline for extended time due to oiling and cooling concerns. Having said that, gered at 3.73, I am certain the car will redline inside a mile on my smallest tire. I am equally certain the car will top out in 1,5 miles on my biggest tire.

Since I have the 3.08 in aluminum, I am thinking of simply installing it with a Mini Spool. Lightweight and cost effective, it seems appropriate for the application in my thoughts.

3.08 on my small tire is around 150mph, on the big tire around 170mph in 3rd gear at 6k.

Does this seem reasonable?

RD
 
Thanks again for all the replies and the advice. I find huge value in all of it.

We want to do this in a manner that folks respect, and raise some funds for ALS while we are at it. And not get killed or waste too much money breaking stuff.

For perspective, Lincoln Engineering ran a Mark VIII to 183mph on 2,47 gears in third. I assume a 26.5" Tire. That was Bonneville, with the longest flying start in the world. If we get to Bonneville, that setup seems good to me. That car was allegedly stock and about 300hp.
My MN12 is significantly lighter than a Mark VIII, even with the cage barely 3500lbs.

As I stated above to Terminator, I have reconsidered the situation after all this input.

I think the best and most cost effective solution is to forgo the full gear change and rebuild process for the Aluminum housing, and forgo adding the locking carrier and Trac Loc LSD element.
We can remove the open carrier and spider assembly and replace that with a Mini Spool and an gasket/oil change. That should yield a lightweight fully locked 3.08 Final Drive assembly we can swap out, and leave the 3.73 with TL intact.

I have to install the Airbag kit, new shocks and the C-Clip Eliminators as well as get the Final Drive together.

RD
 
MadMikeyL said:
I would just run the 3.08 open as is. Once you’re out of the hole, a trak-lock or a spool isn’t helping any.
Click to expand...
I have great concerns about traction in this car. That said, your point is one we considered. The plan is to put the open 3.08 in the car and make some tests. If its okay, I would rather leave it alone and drive the thing. If it is still a slippery pickerel or one wheel peel factory, we can take measures to correct that. My first option is the Mini Spool, second an LSD device.
 
The whole problem with the 3-4 is that you engage one band around a component, while another clutch releases. It heats up like crazy.
Another thing that can happ cen is the stub shaft breaks. If it shifts really hard, you can break the stub shaft in 3 pieces, lol.
www.svtperformance.com

WOT 3-4 upshift with a 4R70W? Better think twice.....

Here's one reason why: This wasn't a WOT upshift either-I pulled out of the throttle and then hit the OD cancel button before I got back in the throttle.It pulled for a fraction of a second in OD,then bounced off the limiter-no 3rd or 4th gear. Snap goes the stub shaft.....:eek: Best...
www.svtperformance.com
Jl was a valued member .

Here is one more thread, about later trans problems, on a marauder.

4R70W Transmissions, My Experience & Thoughts with them...

Theres been quite a bit of talk lately (some of it misleading) around the current Over-Drive automatic known as the 4R70W that comes in the 03 Marauder and I thought I would share some of my experience and insight. I want to mention that Ive been into putting Fords modern rear-drive...
www.mercurymarauder.net
The big point is the programming in the eec And the jmod are crucial to get the trans shifts right.
 
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he really is the guru. :) his tuning book is a must read if you have the prp. Greg Banish also wrote a book, but it wasn't as helpful.
 
I appreciate the information.
Don has been a true gentleman and we look forward to the pleasure of learning. His credentials set the bar. He turned us on to our local dyno shop.

This all worked out great.
We will set it up with the open 3.08 and bring along a Mini Spool, gasket and oil just in case.
Thats a good solution in my view.
 
I've gotten my SC up to >130 mph in ~1/2 mile. Grogg I think your Cd is a bit high by my memory what was listed for the Tbird is a ~0.28. When I did the math years ago my car is RPM limited to 155mph, 3.73 and ~350Hp. AOD is alot easier to deal with this with the right valve body.

From my understanding you want to get the weight up on the car to help with traction and stability, for once you over 40-50mph drag is a bigger concern than mass.
 
Actually Tbirds are .31, Cougars are .36

.32 and .38 Cd sounds more like the 87-88 Fox Tbird/Cougar numbers.
 
When we started out we were searching for traction with the open 3.08 and NPI engine. It was running really well but could not leave anything in a hurry. It was all one wheel peel or the traction assist prevented you. To the point about adding weight, we considered that and settled on moving the battery to the trunk. Suddenly we found some traction and right away it started throwing the 1-2 shift. I found Jerry's white paper and j-modded the thing to short circuit the 1-2 trigger as he outlines.
 
Grog6 said:
I was wondering how fast I reasonably could have gone on that last drive home during the pandemic, where I managed to drain all the oil out the pcv valve, lol.
Over about 3k rpm, oil stays in the pass head. You'd think it would spill over the front edge, but apparently, it gets to the pcv valve first. My oil seperator in that vacuum line was full, as was the intake manifold. There was no oil in the crankcase. I ran 5500 rpm in 4th most of the way home; the gps said 165 peak, and I seriously wondered if that's possible. I'm still unsure. Lazarus is PI cams, pi manifold, true duals, and a tune I wrote. Rev limit is at 5500, and I was bouncing off it most of the way home. I passed a trooper radaring, and he didn't even pull out.
I bought a gps after I wasted the stock speedo changing outthe gears. :roll:
Click to expand...
I have read some about the oiling issues and noted your comments. This is a concern for us, and experience with the issue is helpful.

As I understand it, the issue is multi-faceted but mainly there are drainback problems. At higher rpms the heads fill with oil.
I am told the causes are too much oil pump and the cam chains acting as oil escalators,
On my list of "must haves" is the Livernois drain back extension kit
Also a large capacity separator tank, 3 or 6 port to replace my small one.

I have PCV on each cover into glass air filter canisters and then into the seperator. One line into the manifold from the seperator. The seperator fills up way faster than I have seen before. I run a dual filter with the big motorcraft truck filters on it.

Are there any other simple wys to correct this issue?
 
you could add something to scrape oil off the chain, but IDK.
 
Grog6 said:
you could add something to scrape oil off the chain, but IDK.
Click to expand...
I have seen some complex plumbing solutions that look effective but not simple or cheap. Its a vexing problem.
The DOHC pan is great with the windage tray and kickout built in it, and the extensions get the return below the turbulence to a degree.

You must have left quite the smoke screen cooking off 5 quarts of 5W30. If the catch can fills up, the oil gets gulped out of it.
 
As far as baffling and scraping the mark oil pan is actually identical to the MN12 pan other than the kickout. Mark VIII oil pickups, at least of the HO variety have additional baffles to prevent windage from going up the drainbacks however, that and the flow capacity of HO pumps is the biggest difference between 2V and 4V oiling
 
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