I currently have the Level Ten valve body upgrade and a tranny oil cooler for my 5AT.

Is there a known solution for the 5AT that will enable it to survive 450+ WHP?

Every year or so, I search around these and other forums but apparently few folk try to make the 5AT work with FI and I find little or no new information. I don't quite understand this since I've had both manual and AT and (with a manual shift capability) i much prefer the AT. This is obviously a minority view.

Level Ten talks a convincing talk, but comments on them are mixed. Personally, it took months and threats of legal action to get my $1000 core charge refunded after I did their valve body upgrade and sent my OEM VB back to them.

The VB upgrade performs as advertised, but my engine is still N/A, so its survival hasn't proved much.

Unfortunately, options seem to be extremely limited in terms of shops that really know the Infiniti automatic transmission, particularly for guys like me who live in the Midwest.

Can anyone give personal experience in upgrading a 5AT that successfully handles FI torque levels? My application would be a daily driver.

Many thanks!

 

Call Mark @ SPG.....they are one of the big boys in that AT market.

 

I believe a VB [ SGP or GTM ] , trq. converter, and tranny cooler will hold 450whp . I dont think the other VB's [ Stillen or Level 10 ] are worth a $hit .

 

As booger posted, that is the setup that I will be doing, VB, trq converter and tranny cooler with synthetic oil.

That should hold up pretty well.

 

Well... What are the typical weak points of the 5AT? Where do ppl seem to say always break down? Is it the clutch packs or bands that burn out? Snapped output shafts or premature worn bearings? Some things you'd be able to fix or improve to handle more hp. Some things are just in the inherent design of the tranny, which cannot.

 

I got a GTM stage 2 trans upgrade, which is a VB and TQ Converter Upgrade......to get to 450whp status I suggest you do a fully built tranny, gtm stage 3 tranny status, then go FI, you won't be 450whp off the bat but you'll be very happy, then after the build, 450whp should be no problem I was running 350whp status with the Procharger w/ the tranny upgrades, very reliable. I want too fully build my tranny one of these days too. Now first I'm getting a hks s.c so lets wait and see how that turns out

 

you really don't need a fully built tranny unless you are going over 500 whp.

 

Yeah I can agree on that too, I guess I was going towards my opinion. But anyways cause for 450whp + status I would do it.

 

All depends on how much power you want to achieve, or should I say trq. If you are happy with 400's the a VB and TC upgrade and oil cooler upgrades is fine but when I got into the 440's I started to feel the trans slipping and at that point I went with the GTM stage 3 system. I am pushing 510 ft trq for over 15,000 miles with no ill effects so far.

 

Bastard!!! I want that much tq too! Im jealous

 

LOL now now, there's plenty of trq for everyone

 

Tim at SFR mentioned the size of the clutches is the limiting factor. Even with upgraded high friction, heat resistant clutch packs, 700 whp is the limit. Sam at GTM rates their full tranny rebuild for 600 whp. I would assume they really mean peak torque...

 

The Jatco JRE5AT used in G has an absolute peak rating of 333 lb/ft and a 7,000 rpm limit per manufacturers specs.
Whether someone can redesign and manufacture the hard parts to survive more without reducing the 100,000 shift cycle life is unknown?

They used a different transmission for the VK56 in Titan so they felt the tranny could not be torqued up easily.

 

Yep, it's not easy, but it can be done, all you need is $$$.

 

Do you know if the G35x uses the same tranny or is different?

I'm in the market for another one, unfortunately.