The "Tan Brick" aka my 1997 Express Cobra conversion

[Nasty-Z]

I now own an 8.1, picking it up tomorrow.

NICE

TOM

[1project2many]

Wow. That's a helluva find. What is the lowest numerical ratio available for the 14 bolt? I'd be looking to gear that thing for 1500 RPM on the highway. Maybe it's time to step up to a 6L90E to gain the extra gear reduction?

Gear  6L90 Ratio          4L80 Ratio
1          4.027              2.48
2          2.364              1.48
3          1.532              1.00
4          1.152              0.75
5          0.852
6          0.667
R          3.064              2.07

2nd compressor is usually aftermarket and can be removed. We have several buses with dual A/C (but nothing with 8.1). All sorts of mischief with dual a/c systems, like belt only available from A/C company at $100 each, and modified belt routing, and idler pulleys not available from anyone. Carier was big designer of systems for years but has now been bought and name changed to MCC. From my vantage they don't have anywhere near the parts or support network anymore. Other players stepping up and trying to fill voids but parts fitment and application is still a challenge. I've got a 250A, $1000 alternator here that was designed to work with a dual a/c and custom alternator bracket on a Ford. It doesn't fit anything else but I'm surely not throwing it away after spending that much $$ on it. I'll fabricate a bracket for something.

[Nasty-Z]

3.42 is the highest (Numerically lowest) gear available for the 14FF

How about an Allison 1000 series and keep the 4.10's ? Works fantastic in my 8.1/Allison 2001 3500 Dually

Allison 1000 Ratios

1st	2nd	3rd	4th	5th	6th*	R
3.094	1.809	1.406	1.00	0.711	0.614	4.480

* 6 speed available 2006-up but it is a retrofit to earlier models.

TOM

[Fast355]

3.42 is the highest (Numerically lowest) gear available for the 14FF

How about an Allison 1000 series and keep the 4.10's ? Works fantastic in my 8.1/Allison 2001 3500 Dually

Allison 1000 Ratios

1st	2nd	3rd	4th	5th	6th*	R
3.094	1.809	1.406	1.00	0.711	0.614	4.480

* 6 speed available 2006-up but it is a retrofit to earlier models.

TOM

I just don't want the added power loss!! My 4L80E already has the dual stator 4.3 converter that stalls 2,300 rpm behind the 350. The 10.5" FF I have has 3.73s in it. I want 4.10s in the back but a good comprimise might also be a 2.96 first gear planetary set in the 80E.

[Fast355]

On a side note I have a line on an entire cam/valvetrain from a very low hour 425 HP 496 Mag Mercruiser for $300 that was given the Raylar treatment. Cam/Lifters/Pushrods/Guides/Studs/Rockers and double roller timing set. The cam and matching tune is worth 50 HP in the 375 HP Marine version of the 8.1 making it the 425 HP HO. I am sure the rest of the gain over the 340 HP truck version is exhaust/intake/tune/loss of the mechanical fan. The cam does its thing under 5,000 rpm as well and has a nice sounding idle.

[Fast355]

I did a little more research and decided what the heck and ordered the cam. Might be a shade big for many heavy haulers, but my Express is fairly light compared to a Dually or a Workhorse. Seems the cam is Mid 220s @ .050 on the intake, mid 230s @ .050 on the exhaust, .510/.510" lift and cut on a 114* LSA opposed to the stock 118* LSA big block cam. For $360.00 shipped for the whole take-out cam kit, it is hard to turn down. 425 HP 496 mag reaches 425 HP before it reaches 5,000 rpm.

[Nasty-Z]

I did a little more research and decided what the heck and ordered the cam. Might be a shade big for many heavy haulers, but my Express is fairly light compared to a Dually or a Workhorse. Seems the cam is Mid 220s @ .050 on the intake, mid 230s @ .050 on the exhaust, .510/.510" lift and cut on a 114* LSA opposed to the stock 118* LSA big block cam. For $360.00 shipped for the whole take-out cam kit, it is hard to turn down. 425 HP 496 mag reaches 425 HP before it reaches 5,000 rpm.

You will like that cam setup , I have used a few , been playing with the 8.1 for a while now and it is a very good swap and power increase for an upgrade. Ray and Larry offer great parts and reasonable (for what they are) prices , problem is its hard to justify all that $$ for a tow pig I suppose , but I did it for the '01 . The 8.1 is IMHO the most underrated gas engine recently , surprised more aftermarket support is not out there , but then again maybe I'm not surprised.....

I just don't want the added power loss!! My 4L80E already has the dual stator 4.3 converter that stalls 2,300 rpm behind the 350. The 10.5" FF I have has 3.73s in it. I want 4.10s in the back but a good comprimise might also be a 2.96 first gear planetary set in the 80E.

Understood.


Good luck Chris , I'm sure it'll be a cool ride.

TOM