Engine issues

driller

driller

El Presidente
chris2523 said:
fantastic. everyone says the mustang PCMs won't turn that kind of rpm.
VIII must have different hardware.
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I know the EECIV PCM (W3Z2) wouldn't rev that high.

The 7K+ rpms is on the 1-2 shift point. Since the acceleration is greater in first gear it will rev past the commanded shift point. What I didn't know until after the tracks closed is you can command over 7000 rpms. When I went to raise the shift points in the tune I was surprised to learn it would not accept anything over 7000. As it turns out, there is a simple switch that will allow a higher commanded rpm for the shift points. I am close to where I want to be with the 1-2 shift but the 2-3 shift point needs to be higher than the current 7K.

What rpm did your motor make peak hp and what rpm did you go thru the traps at last time out?
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According to the dyno, peak HP was around 6300 but again the rpm value was off (low by as much as 500 rpms). Regardless it was very near peak from about 5800 to 6800 rpms (6300 to 7300?).

RPMs going through the traps is hard to nail down on the datalogs since I tend to stay WOT past the mark. Datalogs show it runs out to around 6150 to 6300 rpms.
 
germansheperd

germansheperd

New member
driller said:
I know the EECIV PCM (W3Z2) wouldn't rev that high.

The 7K+ rpms is on the 1-2 shift point. Since the acceleration is greater in first gear it will rev past the commanded shift point. What I didn't know until after the tracks closed is you can command over 7000 rpms. When I went to raise the shift points in the tune I was surprised to learn it would not accept anything over 7000. As it turns out, there is a simple switch that will allow a higher commanded rpm for the shift points. I am close to where I want to be with the 1-2 shift but the 2-3 shift point needs to be higher than the current 7K.



According to the dyno, peak HP was around 6300 but again the rpm value was off (low by as much as 500 rpms). Regardless it was very near peak from about 5800 to 6800 rpms (6300 to 7300?).

RPMs going through the traps is hard to nail down on the datalogs since I tend to stay WOT past the mark. Datalogs show it runs out to around 6150 to 6300 rpms.
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if your peak HP is 6300 and your running thru near or at 6300 I'd sat 4.56s are your best bet.
 
driller

driller

El Presidente
germansheperd said:
if your peak HP is 6300 and your running thru near or at 6300 I'd say 4.56s are your best bet.
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I struggled with that but then concluded if 4.56s were not enough, I'd be hard pressed to do anything else. With the 4.88s, I can run the 26" tire and if it's too much gear I can move up to a 27" tire or even a 28" tire if needed. I concede the 4.88s are on the edge but the 4.56s are just too conservative.
 
driller

driller

El Presidente
I took some time in the garage today and tested the torque range of the Thump tensioner as well as the steel Cobra tensioner I had been running along with a new stock tensioner I had in the parts bin.

I clamped each unit in the bench vice and utilized a 3/8" Snap-On torque wrench to measure the torque required to start to rotate the tensioner and the torque required to fully rotate the tensioner arm just short of the stop at maximum design travel.

The Cobra steel tensioner...

Cobra.jpg
24-31 ft lbs.

A stock Mark VIII tensioner...

Stock.jpg
28-33 ft lbs.

The Thump Racing tensioner...

Thump.jpg
50-55 ft lbs! :eek-large:

The stock tensioner and the Cobra tensioner were in the same range and I guess one could surmise the used Cobra tensioner had some age that accounted for the slightly lower torque numbers.

I had to order some M8-1.25 x 35mm SS hex head cap screws to be able to mount the new tensioner since the mounting bosses were noticeably thicker. I only had 2 of the 35mm length. The 40mm cap screws were too long and I was uncertain the 30mm ones that I had removed would not have enough engagement. I'll post pics of the new tensioner and idler installed once I receive the cap screws.
 
driller

driller

El Presidente
I found a thick washer for a 40mm bolt and went ahead and installed the Thump Racing tensioner, double bearing idler pulley and the Gates Racing belt.

IMG_1111.jpg

IMG_1113.jpg

IMG_1114.jpg

IMG_1115.jpg

IMG_1116.jpg
 
KStromberg

KStromberg

Vortech kicked in yo
That belt isn't going anywhere now! Lol. I suspect you had the same flutter issues I did. The preload simply isn't enough and those rpms you are turning really exacerbate the tensioner hop. That's like the only shiny thing on my front timing cover. LMAO

The tq values are interesting. We just compared the two in a vice by feel and the steel arm cobra tensioner I had was sloooooopppppy. We could push mine by hand. It was beat. Lol
 
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driller

driller

El Presidente
KStromberg said:
I suspect you had the same flutter issues I did. The preload simply isn't enough and those rpms you are turning really exacerbate the tensioner hop.
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Yep, I suspect the brutal 1-2 shift rpm jounce was the cause of the shredded belt I experienced at the last track outing since it occurred right at the point I expected it to shift.

I've had my fair share of tensioner and belt issues with the car in the past when I started pushing 7,000 rpms so it should be no surprise to see them return at this juncture with the even higher rpms. I'm hoping to eventually run a 'short belt' setup which may or may not solve some of the belt issues at high rpms. From what I've learned, long belt paths tend to be more of an issue as rpms and loads increase.

Another avenue I'm exploring is using an over-running clutch pulley on the alternator. This will minimize the induced load on the belt from the inertia of the rotating mass of the alternator windings. The big problem there is with the current setup of the Hogan intake overhanging the alternator, the coolant crossover has to be removed to remove the alternator. I'm pretty sure there isn't room to R&R the pulley with everything in place.

engine copy.jpg

But for now, hopefully the Thump Racing tensioner will tame it down and I hope the 'new' belt and accessory bearings can handle the load.
 
KStromberg

KStromberg

Vortech kicked in yo
Have you thought about doing the "crossover pipe delete" mod? This would solve that issue. I know yours is a pretty blue and all but.....

crossover delete installed.jpg


As far as the belt, I've read that if I drop lower than the 3.33 pulley I'm going to run this year, 8-rib is highly suggested as the Vortech guys start to see slipping belt issues return even once they have already nailed that issue down. I'd imagine this is likely from the higher stress loads under more boost. While you aren't dealing with boost at the moment you are very much dealing with high stress loads in a similar fashion because you have us whooped in the rpm department. Lol. If it continues to be an issue, you might want to consider going 8-rib. Just food for thought....

I've always wondered what my car would sound like at 7800 rpms. I don't think it would be pretty. Lol
 

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driller

driller

El Presidente
The belt is a serious PITA to put on now with the new tensioner.

I awoke the beast from its winter slumber in preparation to take it to a shop for a rear gear change. I pulled the fuel pump relay and cranked the engine a bit to build oil pressure before starting it. When I went to put the relay back in place, I noted the belt had skipped off track on the pulleys. After returning the belt to its proper groove and triple checking everything we fired the engine up.

[video]http://photos.imageevent.com/driller/1993lincolnmarkviii/IMG_1146.MOV[/video]
 
driller

driller

El Presidente
germansheperd said:
You do the 4.56s or 4.88s?
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I went with the 4.88s.

It was supposed to be done today but like everything else with this car, nothing comes easy. To start with, one half shaft refused to pry away from the differential. We had to pull the shaft out with the carrier and after an hour or so on the bench we finally coerced the circlip to failure and removed the half shaft.

We then discovered the Detroit TrueTrac was on its way out and had to change plans from a more or less simple ring and pinion swap to a full on differential swap.

http://www.lincolnsofdistinction.org/vbulletin/showthread.php?35151-Post-a-picture-you-took-today&p=296786#post296786
 
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