aka 951

I thought about the deltagate - but heard to many horror stories. They probably work fine on a street car though. As for bolt in, the LR is unreal - its fits exactly like stock and requires absolutely no mods. To me it was a no brainer. I can run 20 psi up to redline in 2nd and up gears. It is a very very well done piece and the people are great to deal with! Id give the part an A+.

Brent 89 - GT

I think I have narrowed it down a bit. I am thinking that a K27 in conjunction with a LR wastegate and manual controller may be the best bet. Then I have to get the chip and inlet from Autothority. I would go with a Huntley stage two if the price is close to the KKK. Does anybody know where to look for a new K27? Is there a straight K27? Or do all of them have a #6 or #8 hot housing? I kind of thought those were hybrids, whats the scoop?

Perry 951

Well.. it was a number of things that killed the valves. The first few times the belt would walk off the crank pully under load. After inspection many many times, I finally noticed that the brand new tensioner assembly had the idler gear on backwards, allowing the belt to walk off it. After that, the head was redone again, and the #4 exhaust valve keeper broke and allowed the spring to shove the lifter into the path of the cam. The cam then wedged the lifter into the bore sideways and cracked the cam tower, bent the cam, and shut down the motor.

It is almost back together. Head studs were completed last night, and the head, cam, and exhaust are all back on. Hoping to get it back the 2nd.

Macabre

Brent: The K27 is available from Windward and Powerhaus (perhaps others) with either the #8 or #6.. I'm not sure which is the "basic" arrangement and which is a "hybrid" or if either are either.. but the price seems to be the same regardless of which turbine you get at least from windward. I'm still looking around for better prices as well since it seems like with a K27/6 you're only buying a new compressor side which shouldn't cost $900.

Danno

I would avoid the AutoThority chips. They program in so much ignition retard that my car was actually slower than stock. This is so you can run something like 21+psi of boost, but unless you max out the boost, it's a losing compromise.

Get the Huntley or Milledge chips.

Brent 89 - GT

Gee Danno, I'm not sure that is totally correct. When I did the mass flow and chips from APE I dropped a full second 0-60, sure must be making more power. I know they reconfigure the ignition curve but for 21 psi???? They do offer different chips for different configurations, why would they short you on performance? Seems counter productive to the business they are in. Besides considering what is will cost me to do a headgasket I think erring on the side of safety is a good thing. Rebuilding the bottom end because of detonation is not an appealing thought.

Danno

Been there, done that and learned my lesson a VERY HARD and EXPENSIVE way. I recommend O-ringing and solid copper headgaskets to anyone who blew a headgasket. This is a misnomer because it's not the pressure that caused the headgasket to fail, but rather the intense heat from detonation that burns through.

The stock (and also the wide fire-ring version) headgasket uses a hollow steel compression ring. The air inside the ring is a very effective insulator, and combined steel, makes for a very poor heat conductor. Solid copper on the other hand, conducts heat to the surrounding head & block a minimum of 8- to 10-times faster (difference in thermal-conductivity). There are guys lurking around who've blown up multiple wide fire-ring headgaskets just weeks apart.

Hmmm... it's tough to quantify multiple upgrades at once (1/4-mile times & speed more accurate for comparisons). I wanted to see how much of an improvement the chips provided vs. the banjo bolt.

So I swapped out the APE Stg-II chips for stock chips in the beginning because I thought something went wrong. Compared to the stock chips at 12psi, I lost 0.7-1.0 in 0-60 with super sluggish partial-throttle mid-range response.

Putting BOTH the APE chips AND the banjo-bolt in did improve my times over stock, but it was a one-step-back two-steps-forward deal. Also noticed that the banjo-bolt didn't give a linear boost increase (lost boost at high-rpm). So I put in an Anderson boost controller which solved that (before John went to work for Huntley).

Anyway, I did a lot of dyno testing and found out that the APE Stg-II chips @15psi were quite a bit richer than stock in the mid-range, but ended up getting leaner up top. At 20psi boost, the fuel-mixture was right-on in the midrange, but got dangerously lean near redline (injector duty-cycle maxed out).

So, I ended up getting a custom set of chips burned by some folks who had campagned a couple of seasons with 951s. Got one set for 14psi and one set for 20psi.

Another way to look at the chips concept is that they are a general purpose upgrade (partly because the computer goes into open-loop operation at full-throttle above 3500rpm). Partly because the manufacturer has to make guesses as to what kind of air-cleaner you are using, what kind of boost-level you can possibly use, the type of turbo and wastegate, with/without cat-bypass, muffler types. As such, they dial in a LOT of cover-your-*** safety type of compromises (rich mixture & retarded ignition).

At any given boost and flow level, there is but only ONE optimal ignition and fuel curve. If you've got a chip that works at 20-21psi, then you know for sure that at lower boost pressures, it's got way too much fuel and the ignition is not sufficiently advanced for optimal and maximum power.

Someone else on another thread (turbo lag?) compared the differences between the APE Stg-II chips and the Milledge ones saying there's a dramatic difference. I can confirm that from my own experience. As a baseline comparison, I've got the same mods as BCAT (Huntley Stg2 BB turbo & MAF-4) and I'm putting down 290hp at 13psi boost with the only major difference being the chips.

Brent 89 - GT

OK Danno, I'll go along with a custom dyno tuned set of chips being better. BUT I am not intereted in a bunch of dyno tuning time, I am at least 150 miles from the nearest shop capable of doing this, and it wouldn't be a Porsche shop. Can Milledge burn a set of chips given a set of mods and reduce the overcompensation built in by the other guys? If not then I am relegated to taking whatever is best "off the shelf" and living with it. I am also not interested in a new engine management system, heck this was a $9000 car that I have already turned into a $20,000 project. I would like to be essentially done after this round (turbo and wastegate). Do you have any advice on how to simply and cost effectively get a better set of chips? BTW I went from 14.2@97mph before to 13.4@104 after the APE MAF w/chips. Maybe its not perfect but it works pretty well.

Danno

yeah, just about anyone who makes these chips can burn you a custom one. You just have to tell them how to modify it from their off-the-shelf settings. Since you already have AutoThority, don't they provide custom burned chips as part of the package? Or something for $100?



Basicly, you want to even out the air-fuel curve so it's flat across the board, then you can adjust the entire thing up and down with fuel-pressure.

howie

how do you feel about using Huntley's product for fuel curve management??

Danno

The Huntley bolt-ons are fine for medium power outputs (up to 350rwhp). They basicly massage the sensor inputs from the air-flow meter to fool the computer into thinking air-flow is something other than it really is. But this still operates within the limits set by the chip programming. Once you start opening the injectors over 85%, no amount of signal-masssaging is going to help.

And the stock DME is too slow to operate in closed-loop operation above 3500rpm and full-throttle anyway. The air-flow/MAF signal is completely ignored, so is the O2-sensor, as well as the engine-temp sensor. It comes down to a straight look-up table of injector-duty cycle vs. RPM. The only way to tune here is by modifying the fuel table in the chip and with fuel-pressure.

howie

SO ABOVE 3500 RPS OR AT WOT THE CHIPS SHOULD TAKE OVER. hOW DO YOU FEEL ABOUT AUTO aTHORITY CHIPS WHEN RUNNING HIGH BOOST. wILL THE FUEL CURVE BE RICH ENOUGH.

Danno

I noticed that the AutoThority Stg2 chips at full-throttle are too rich in the mid-range RPM and they get too lean in the upper RPMs. Adjusting fuel-pressure to make high-RPM safe would end making your mid-range even richer.

This made for really lazy partial-throttle/mid-RPM response. I wouldn't seriously consider the AutoThority chips for anything. There was another thread (turbo lag?) that compared these with the Millege.