quad4 or twincam with auto? (Page 2/2)
eesparza84 DEC 19, 02:40 PM

quote
Originally posted by 82-T/A [At Work]:

You've re-peaked my interest.

I just found an extremely rare SuperCharger kit for the LD9. This is the first one I've literally ever seen on eBay. Not too many people got them, but it bolts right up to the LD9 and re-uses everything on the engine, replaces the intake, and the factory TB bolts to it. It was a GM performance parts factory-ordered option.

https://www.ebay.com/itm/267410392633

Not gunna lie... I may buy this if you don't... haha... I've always wanted a TwinCam Fiero. It even comes with the ECM, meant for an automatic (meaning it's been reflashed to support the supercharger and larger injectors).

If it's still there by Monday morning, I'm buying it.


I saw that, to bad im not full of money right now otherwise i would get it... but yea ive decided this is the swap i want to do. now to find a quad 4 4t60 and a twin cam engine. which would be better for the swap, an manual ecm or auto ecm when using an older hydro trans?

mind you this will take a few years to build up for...

[This message has been edited by eesparza84 (edited 12-19-2025).]

olejoedad DEC 19, 03:38 PM
The transmission control logic is much different between the two transmissions.

You would want an ECU that could control the engine and the transmission you choose.

From experience I will tell you - the 4T60-E is an excellent transmission. It is shifted by the ECU, rather than by governor, vacuum and throttle valve cable like the 4T60. It shifts quickly and optimally and is very rugged.
82-T/A [At Work] DEC 19, 09:00 PM

quote
Originally posted by eesparza84:

I saw that, to bad im not full of money right now otherwise i would get it... but yea ive decided this is the swap i want to do. now to find a quad 4 4t60 and a twin cam engine. which would be better for the swap, an manual ecm or auto ecm when using an older hydro trans?

mind you this will take a few years to build up for...





I'll x2 what Old Joe said... I loved my 4T60E.

That said, they do fail if they're not well taken care of... so if you get one, you'll want one that's been rebuilt... but they are FANTASTIC transmissions... they shift well, and easy to control. They work well with the TwinCam.
Raydar DEC 19, 09:41 PM

quote
Originally posted by 82-T/A [At Work]:

I'll x2 what Old Joe said... I loved my 4T60E.




Kind of a tangent, but my 4.9 swap came with a 4T60E. It "worked okay", but I hated it.
Cadillac designs their drivetrains to move 4000+ lb vehicles down the road as efficiently as possible, with a minimum of drama. But, as installed in a DeVille, the 4T60E does nothing quickly. I was so unhappy with it that I almost sold the car, but ended up selling a different vehicle instead.
I then swapped a Getrag in. The gearing is completely wrong for the 4.9 (I can hear certain forum members having heart palpitations, even from here), but it's still a riot to drive.
If I had the funds available, I'd do an F40 with the 3.09 FDR. All it takes is money. And fabrication skills. Both of which I find to be in short supply, just now.

[This message has been edited by Raydar (edited 12-19-2025).]

82-T/A [At Work] DEC 20, 08:25 AM

quote
Originally posted by Raydar:

Kind of a tangent, but my 4.9 swap came with a 4T60E. It "worked okay", but I hated it.
Cadillac designs their drivetrains to move 4000+ lb vehicles down the road as efficiently as possible, with a minimum of drama. But, as installed in a DeVille, the 4T60E does nothing quickly. I was so unhappy with it that I almost sold the car, but ended up selling a different vehicle instead.
I then swapped a Getrag in. The gearing is completely wrong for the 4.9 (I can hear certain forum members having heart palpitations, even from here), but it's still a riot to drive.
If I had the funds available, I'd do an F40 with the 3.09 FDR. All it takes is money. And fabrication skills. Both of which I find to be in short supply, just now.





That's interesting... what were some of the issues you were having with the 4T60E? The only cars I've owned it in, were high-revving 4 cyls... I don't know what the gearing was... but I'd guess that would have a lot to do with it too.
olejoedad DEC 20, 09:00 AM
The drivetrain that I have in my Formula (4.9/4T60E) is from a 93 Eldorado, it is geared much differently that the transmission from the Deville.

The first thru fourth drive ranges are the same, but the differential is a 3.33 and the chain sprockets are 35/35.

It's ratios are similar to the 88 GT TH125C, but with and overdrive 4th gear.

GM built a lot of variations of the transmission back in the day, and they were all ruggedly built.

I wasn't excited about buying the car with a 4.9/automatic, and had plans for putting a Frankenstein Muncie 4 speed in it, as all of my previous Fieros had been 4 speeds.

That changed after I drove the car from Nashville TN, where I purchased it, back home to Michigan. The transmission/engine combo has been bulletproof, economical and quick for the last 17 years.
82-T/A [At Work] DEC 20, 10:14 AM

quote
Originally posted by eesparza84:

I saw that, to bad im not full of money right now otherwise i would get it... but yea ive decided this is the swap i want to do. now to find a quad 4 4t60 and a twin cam engine. which would be better for the swap, an manual ecm or auto ecm when using an older hydro trans?

mind you this will take a few years to build up for...





Sorry, didn't mean to make this about me... but I just asked if he was willing to take $1,000 USD for this.

You may end up causing me to build a TwinCam Fiero as a result... ugh...
eesparza84 DEC 20, 12:56 PM

quote
Originally posted by 82-T/A [At Work]:
Sorry, didn't mean to make this about me... but I just asked if he was willing to take $1,000 USD for this.

You may end up causing me to build a TwinCam Fiero as a result... ugh...




if you do please document, maybe we will revive twin cam swaps! i just feel like a 4 banger is right for this car.
82-T/A [At Work] DEC 20, 02:28 PM

quote
Originally posted by eesparza84:

if you do please document, maybe we will revive twin cam swaps! i just feel like a 4 banger is right for this car.




I got him to lower it down to $1,200 Canadian, which is like just a bit under $1,100 bucks. The thing that concerns me is the warning saying I'm going to get import fees. What are these? This is a used product, so I'm not sure why it would have tariffs associated with it. Any idea what I can expect to pay? Shipping is like $250 bucks already.
Raydar DEC 20, 04:29 PM

quote
Originally posted by 82-T/A [At Work]:

That's interesting... what were some of the issues you were having with the 4T60E?



No real "issues". Just the original application, as Joe alluded to.
I forget what the sprocket ratio was, but the overall FDR was 2.97.
When I stomped the gas, it was like I was the captain, telegraphing down to the engine room for more steam. It downshifted. Eventually.
Upshifts were smooth, but not quick. I even replaced the vacuum modulator with an adjustable aftermarket piece, and then cranked down on the adjustment in the direction that should have "firmed up" the shifts. It made a slight difference. Sort of.
I firmly believe that if I had had the Eldo drivetrain swapped in, instead of the DeVille, that I would have been happier.
I even thought about swapping the internals, to provide a lower ratio, but that opens up its own set of related problems. I'm pretty sure the PCM would have noticed the change, and freaked out. I think they look for "slippage", and such, which a 3.33 would have "simulated".
I looked at the tune, and there was no easy way to program for a FDR change, that I remember. (I've slept since then, so I could be mistaken.)