My 2006 MCS Convertible has a seized engine at 116k. I need to source a new one and I'm not sure I have the space or ability to rebuild one myself. I'm leaning towards a street/track level performance engine from RMW with a 250hp and upgrading the headers and exhaust.

But I have some questions:

1. How much torque can my Aisin 6-speed automatic transmission (GA6F21WA) handle? The figure I see online states 220 Nm / 162 lb-ft of torque. Could that handle the 250 hp?
2. Should I even consider it with an automatic? I see most of the performance builds seem to be on manuals. I like my paddle shifters even though they are not dual clutch.
3. RMW has a great reputation on here but are they still around? The web site doesn't have any contact info and no updates on here since 2018.
4. If I were to rebuild the engine myself, what additional tools would I need? Engine hoist, etc. I have replaced the head gasket successfully, but this would be next level.

Any thought are welcome.

 

sorry to hear the bad news. 116k is pretty low milage for a car that old. What happened?

is this your daily driver or do you have a second auto?

how do you feel about a k24 swap?

 

You are at the good / fast / cheap point. You can have 2. Not all 3.

I have a 2005 r53 - also Auto. Bought new. It has 185K on it. It has never been opened up. I had the auto rebuilt in Feb. it cost north of $5800 to do that. It was done by a reputable shop and has a 2 year, 24000 warranty. I bypassed the stupid beer can heat exchanger and went with a real trans cooler. This car lives in SoCal, it is just a loop with no thermostat on the cooler. This car has a stock ecu, a Dinan cold air intake, and a UUC Cat back exhaust, and a Dinan pulley. It is quick, it is fun. I estimate 180 hp on the high side. Torque - no idea, a bit more than it left the factory
with. I think you are the same poster who I suggested to check with allmagauto in Florida about a used motor. I’ve not bought motors from them, but I have bought other items. I’ve found them good to deal with. If you put a fresh strong motor in, and you drive it in a spirited manner, you will likely need a new transmission. My rebuild has been terrific - no more clunks between drive and reverse, no hanging up when hot in traffic, and it took a heat load off the cooling system. This is my experience, yours might be different, but what you posted looks like an easy 10k adventure.

 

$5,800 to rebuild an automatic transmission?

 

Yep - it’s not a GM 4L60E. It’s quite awesome now.

 

It's our second car, plus we don't commute by car, so low miles

K24 swap seems really hard. 😮

 

The cheapest way would be finding a donor car, and selling off everything besides the engine block. The superchargers alone are about 1/4 the cost of the engine, on top of selling the transmission and you've paid for half the donor engine already. It is not overly complicated, just remind yourself its all nuts / bolts and random fasteners / wiring ect. Its like a lego kit.

Tools, engine hoist will be a must. Unless you can somehow balance the engine on floor jacks while aligning things to reassemble. (its often easier just having the right tool, a hoist)
Besides the hoist its all common tools, sockets, wrenches, pliers ect.

If you had the patience and time to do a headgasket you can swap an engine no problem. A headgasket is like fine surgery where swapping the engine is basic construction to me. Do not be intimated by the scope of work by any means.

It really depends on what you want,
- the easiest route is to get a brand new engine $$$$$
- next would be getting a donor engine already out of a vehicle $$$$ (sketchy unless a reputable seller)
- last getting a donor vehicle and doing all the work $$$. Learn the most this way, and end up with an abundance of spare parts lol.

Best of luck deciding!

 

I does seem like it would be some work, but they have kits these days. i've never done it.

https://rptcreations.com/collections...41800252686514

 

Here is a 2007 NAM thread with a number of responses to your question of how much horsepower will the automatic transmission survive: https://www.northamericanmotoring.co...orsepower.html

You could also call Jan at RMW and ask… he certainly has the experience to know what is "realistic" with the automatic. (He was good at returning my calls, but he got way more than he could answer when I visited him.)

I have one of his stroker motors, and it's been bullet-proof, but I also have the 6-speed, so not relevant to your question. Note that the convertible weighs ~200# more than the hatchback, so a bit extra strain on the auto trans for that.