I just checked some of my logs..

stock evo 9, stock turbo, kelford 264 cams, about 390-400 mustang hp at the crank, at 11.2 AFR will be at 93% IDC on stock injectors with warlbro at 7000 RPM. In my book this is maxed out turbo for the road and track (no dyno queen maps over here).

So I would say that for 71 HTA you really need larger injectors..

other case is e9 with s2 cams and HKS 7460, on ASNU 1000 cc injectors (that I prefer), which will do about 460 hp at the crank, and at 11AFR at 7000+ RPM will run 73% IDC

in any case... get some larger injectors..

 

im beginning to think so, KIKI

 

would be a shame to leave all that power on the table..

When I bought my 71HTA injectors were the next thing... shame I never installed that turbo to try....

 

I vote for larger injectors to make the turbo swap worth it.

 

Ditto! You'd never know when you'll crave more power in the future or decide to do a 5 speed swap or upgrade/rebuild the 6 speed to handle more power!

 

I don't see a 71HTA overpowering a 6spd. Maybe if it's really high-mileage. I wouldn't let that be that hold up.

 

6 speeds have been known to fail at stock HP levels, and to hold up fine at 600wtq. It's a toss-up, man. Just go bigger injector, tune the engine safely, and keep the hard launches to a minimum. That's about all you can control.

 

Exactly.

 

I myself have a 5 speed so I'm not all too familiar with the 6 speed. I've heard much the same - people with 600 hp and no issues and people who are more or less stock with issues. I only mentioned it because the OP listed his stock 6 speed as a point of concern with regard to hp restrictions. From what I've gathered it seems that 3rd or 4th gear fail most commonly. Heat is an issue for road racing guys and I think oiling passages are commonly upgraded or added during rebuilds.

 

Fourth gear is smaller than on the 5spd and can get hot and fail. I had 130k on my last one and it was doing fine until an unrelated issue killed it. That was 110k of neglect from the previous owner, then a hard 20k from me LOL. I use my car for autox and road racing, though I have never run more than 450whp through it. Fluids are changed yearly, despite very few miles put on it. I could be one of the lucky ones, though.
OP would most likely be just fine with a 6 or a 5, IMO but many, many others will disagree. They are probably the ones you mention with failures.

FWIW to OP: some of us prefer the 6spd. It shifts VERY nice and I like the ratios. Things I didn't like about the 5:
1. position of the shift lever, in relation to the steering wheel (sits 1-2" farther back from the wheel).
2. the way the shifter feels when going through gears
3. gear ratios. 1st to 2nd or 2nd to 3rd. I forget which.. but I really hated it.

Things I liked:
1. it was a lot lighter and smaller, so easier to bench press into place LOL
2. no worries about HP limits.
3. aftermarket support (shifters, gears, cooler/fluid director thingies, etc)

all my opinion, of course, but food for thought.

 

We're both in the same boat. 05 MR with a 71 HTA. I'm just as worried about my transmission.

The way I'm looking at it is that maxing out my setup on 91 octane will be more than enough for me, and should leave the 6 speed being reliable minus launches. E85, well that's a different story.

 

450whp for two years. My 6 works great.

 

I'm currently preparing for an engine build, planning on ~450-500whp (not a requirement, just an anticipated result) using a 6 speed. I've got about 120,000 mi on the clock, but the drivetrain has already been rebuilt/upgraded by TRE, and I installed my own transmission oil cooler where the original ACD pump resided, and I do not anticipate issues with reliability. I DO NOT DRAG RACE. Hard launches are few and far between. That's probably one of the biggest reasons for 6 speed failures, along with heat soak. Minimize those two main issues, and it can reward you well.

 

Very nice to hear. I always get worried about my trans, but I'm pretty confident in my ability to not beat it up too much. I've heard of plenty of people pushing big power through them and not having them blow up.

 

You just have to be sensible and realistic.
If not for the fact that my car may be sold this week, I do have plans to install lines, a cooler, and a pump. I figure, "why not?" Plus it sounds fun.