Aftermarket WG's, do they open at simillar spring pressure (4psi) as the stock WG?

[wild man]

I'm considering going with an aftermarket WG, but only if the answer to the question in the title is yes. Otherwise knock protection capability will be reduced (crippled) even more.

[CPR]

You can get a waste gate set-up for practically any spring pressure.

Not sure I follow you though on 'crippling knock protection'? You are safe way above stock

[wild man]

Originally Posted by CPR

Not sure I follow you though on 'crippling knock protection'? You are safe way above stock

Not if running a 20psi banjo bolt, and you get a bad batch of fuel. Boost cut invoked by the knock control regulator yields AT LEAST 7psi with a 4psi WG spring, so I do not wish to go any higher on the spring pressure.

[bebbetufs]

The Lindsey Racing dual port has a stronger than stock spring.
I don't know about the single port, but what is the point in an aftermarket WG if the spring is just as weak as stock?

[wild man]

You do have a valid point. I think that the reason the factory went so low was so that it would be possible to enter a fail safe mode if necessary, for reasons of preventing the engine from self destructing, due to situations such as uncontrolled knocking due to bad fuel. For some reason, I like that school of thought. I think I will just end up getting a valve job done on the stock WG so it does not leak, and then modify into a dual port configuration. In most cases, I will take modified stock over aftermarket anyways.

[CPR]

Originally Posted by wild man

Not if running a 20psi banjo bolt, and you get a bad batch of fuel. Boost cut invoked by the knock control regulator yields AT LEAST 7psi with a 4psi WG spring, so I do not wish to go any higher on the spring pressure.

First, that wasn't the question you asked, nor did you ever mention using a '20psi banjo bolt' in tandem with a WG.

Second, how do you plan on controlling boost (MBC, EBC, EBS, SA)? If all you are doing is changing WG because your OEM is defective, then it doesn't really matter as the controlling mechanisms are the same.

Third, no offense, but in my 31 years of driving (7years in the 951) I have never had a bad batch of fuel and therefore do not see the point in structuring a hi-po build around the remote possibility of getting some bad gas. There are plenty of things that can wreck a motor that need to be taken into acccount when building, but this is not one of them IMO.

OK I'll bow out of your threads now, as obviously, I am not even remotely following what you are trying to do.

Either way, good luck with your projects.

[wild man]

I'm in the process of a major HP upgrade right now. The 400 range is what I am shooting for, from my current 330-335. But I am using the 20psi banjo bolt provided with the APE MAF kit that I am running, and would prefer not to go any higher than that on boost. I also want to retain as much of the factory knock control protection as possible. In order to do that, I need to keep the factory cycling valve, coupled with a WG having similar spring pressure as the factory one. The clincher is that I also want a WG that will not leak any pressure before full boost is achieved. Is this a situation of wanting to have my cake, and eat it too?

[Born2bwild1191]

Doesnt the spring tell you when it will begin to leak boost? Like a 4psi spring will cause boost to start leaking at 4psi? I could definitely be wrong, but I thought that's how it worked.

[nize]

not if you run dual port mode.

[wild man]

Originally Posted by Born2bwild1191

Doesnt the spring tell you when it will begin to leak boost? Like a 4psi spring will cause boost to start leaking at 4psi? I could definitely be wrong, but I thought that's how it worked.

This is where you are wrong: With these cars (and many others), it is not a straight-up 1:1 pressure ratio between boost level and the amount of pressure reaching the WG. With a 20psi banjo bolt, the ratio is 5:1, meaning 20psi in the manifold will apply 4psi to the WG. Stock ratio is about 3:1, where 12psi at the manifold equals 4psi at the WG. And I would not use the phrase "starts leaking at 4psi", but rather "starts opening at 4psi" instead. Leaking is when exhaust gasses are "bleeding" through it when it is supposed to be fully closed (less than 4psi applied to it). THAT is where dual port mode helps out, by counteracting the effect that exhaust pressure exerts on the valve, trying to force it open before the pressure signal at the diaphragm tells it to open.

[CPR]

Originally Posted by wild man

I'm in the process of a major HP upgrade right now. The 400 range is what I am shooting for, from my current 330-335. But I am using the 20psi banjo bolt provided with the APE MAF kit that I am running, and would prefer not to go any higher than that on boost. I also want to retain as much of the factory knock control protection as possible. In order to do that, I need to keep the factory cycling valve, coupled with a WG having similar spring pressure as the factory one. The clincher is that I also want a WG that will not leak any pressure before full boost is achieved. Is this a situation of wanting to have my cake, and eat it too?

Well that depends on several factors.

What are you currently using to reach 335hp? A stock wastegate and turbo can't get you to that number, so what combination are you using now? Perhaps we can improve on that to achieve your goal of 400.

[wild man]

Originally Posted by CPR

Well that depends on several factors.

What are you currently using to reach 335hp? A stock wastegate and turbo can't get you to that number, so what combination are you using now? Perhaps we can improve on that to achieve your goal of 400.

I beg to differ. The $1800 APE 20psi MAF kit is supposed to take a K26/8 equipped "S" car to 320HP. Adding a 3" cat back exhaust with a high performance muffler and empty cat adds a good 15 HP to that. The stock injectors are definitely maxxed out at that point (@ 2.5bar fuel pressure).

The currently being worked on improvements include 55# injectors, (& fuel pump upgrade, if deemed necessary), 15509 camshaft, 3" intake plumbing to a K27/8 turbocharger, catless 3" exhaust piping with open WG dump pipe. I will also be doing DME tuning to optimize performance and efficiency (and KLR tuning when Rogue Ant has the xdf file ready, but for improvede engine protection - not performance). Extra gauges include A/F gauge, 25psi boost gauge, 6700rpm shift light, & knock counter.

[CPR]

Originally Posted by wild man

I beg to differ. The $1800 APE 20psi MAF kit is supposed to take a K26/8 equipped "S" car to 320HP. Adding a 3" cat back exhaust with a high performance muffler and empty cat adds a good 15 HP to that. The stock injectors are definitely maxxed out at that point (@ 2.5bar fuel pressure).

The currently being worked on improvements include 55# injectors, (& fuel pump upgrade, if deemed necessary), 15509 camshaft, 3" intake plumbing to a K27/8 turbocharger, catless 3" exhaust piping with open WG dump pipe. I will also be doing DME tuning to optimize performance and efficiency (and KLR tuning when Rogue Ant has the xdf file ready, but for improvede engine protection - not performance). Extra gauges include A/F gauge, 25psi boost gauge, 6700rpm shift light, & knock counter.

APE has an $1800 kit? Do you have a link for this kit?

But more importantly what was the dyno reading? What AFR's were you running according to the dyno at 20psi?

Also, you may look at moving to 72# injectors. The stock ones are only good for around 300hp and the 55's will be at full duty in the mid 3's. This way you won't have to upgrade them again when you approach 400. Just a thought.

TIA

[wild man]

Here's the link:

Autothority | Pitstop - Products - Porsche, BMW, Audi, Volkswagen & Mercedes Benz Auto Repair Service - South Riding & Chantilly, VA

According to them, dyno readings max out at 320HP - I haven't done any dyno runs. AFR's are just a bit over 12. Since I already have the 55# injectors (haven't installed them yet though), I'm not buying a set of 72's unless I see that the 55's aren't cutting it. But I would probably try a 3bar FPR first, anyways.

Other things I am keeping an open mind to, but have no immediate plans for are: up to a max boost pressure of 25psi, and up to a max rpm limit of 7500 (I'm now at 7040). There's got to be an S-load of power there, but I'm not ready to go there at this point in time. Gonna need to upgrade my clutch soon though.

[CPR]

Probably not what you want to hear, but that kit puts out no where near what they claim, unfortunately.

Moving on, you will need to use a 3bar with 55's for them to effectively work. Although as I said, if your goal is 400 55's won't do it....even @ 350~ish they will struggle at continued load~dutycycle.

As for upping the boost to 25psi, that is definitely not recommended, nor is increasing your rev limit past 6.5k. These motors are simply not efficient in that range, and definitely not built to be reliable under that stress.

Just some thoughts.

[wild man]

You seem to know quite a bit. How long have you been running these cars? And what is the the HP # that you believe is true for the APE 20psi MAF kit (on a stock turbo S)?

While these motors may not be "efficient" beyond 6.5K, they are indeed capable of putting out a hell of a lot of horse power in that range. The dyno graphs just continue to go straight up, with no level-off.

What kind of splitters to you make, or should I say, bake, anyways?

[wild man]

I guess I should also mention something that I forget to say about the WG pressure not being equal to boost pressure on these cars. What I said ONLY applies if running the factory boost control solenoid (aka. the cycling valve). If using a manual boost controller, the ratio WILL be 1:1. So that obviously would not work very well with a stock WG.

[CPR]

Originally Posted by wild man

You seem to know quite a bit. How long have you been running these cars? And what is the the HP # that you believe is true for the APE 20psi MAF kit (on a stock turbo S)?

While these motors may not be "efficient" beyond 6.5K, they are indeed capable of putting out a hell of a lot of horse power in that range. The dyno graphs just continue to go straight up, with no level-off.

What kind of splitters to you make, or should I say, bake, anyways?

I am not sure if what I know qualifies as 'quite bit', but I have been inside these cars for quite a few years. Either way, I still learn something new about them daily it seems...

The reason I mentioned the numbers with the APE equipment is, I was pretty good friends with Minh over at Autothority (may he rest in peace) and would like to think that through the years I have a fairly good understanding of their products.

First, they did not have a '20psi kit'. Their recommended settings never went above 17psi, and that was using an aftermarket wastegate. Their standard banjo was at ~15psi. Their chips are not designed to run high amounts of boost, and they know it. Hence why they will not do any install resulting in higher net gain of 17psi and even that pushes the limits of safety (they run lean up top=BOOM) with their burn.

Second, their claimed HP numbers are based on a car that had several other upgrades (exhaust, wastegate and headwork) that maximized their dyno readings. A standard car could never hit those numbers without a similiar combination of modifications. The actual HP gain is closer to 35hp with their chipset/MAF/banjo.....at the crank.

So I would think a Turbo S (in PERFECT mechanical/electrical condition) would see about 280~ish at the crank, which would equate to roughly 238-243hp at the wheels (rwhp).


As for making power past 6.5K~7k RPM, I will have to respectfully disagree with you here. They do not, and will not....or shall I say cannot. The drawback design of their efficiency relies heavily on the limited flow characteristics of the 8v head. It simply does not flow enough to continue to make HP up high...NOR will the bottom ends of these engines last very long at such high engine speeds. But none of that is news. That is pretty common knowledge and often has been discussed 'ad-naseaum' on several boards.

While the 8v~ 2,5L is a good solid engine it was never designed to be a high revving free flowing counterpart like the ricers are. Doesn't mean it can't make good HP/TQ numbers, just does it differently in a different range is all.

[wild man]

I'm going to have to respectfully disagree on all counts. APE DID make a MAF kit that included a 20psi banjo. I have one and so do numerous others, although many of them choose to run lower (like 15-16).

Nize did a test where the ONLY upgrade was the MAF itself - no chips, no increase in boost. The improvement he saw was in the 30-35HP range.

And I don't know where you got the idea that these engines don't like high revs, they love em. I believe you are completely misguided in reference to this. They probably have the best flow characteristics of ANY 8V engine ever produced. They most certainly can, and will, deliver at high end (up to 7500rpm). I've never driven any 8 valve that was anywhere close. And contrary to what you are are saying, these engines are known to have very robust bottom ends.

MY 924S, in which the weltmeister chip allows the revs to go to 7500, has so much HP up there, if you are not looking at the tach when all-out shifting for acceration, you WILL hit the rev limiter, because the power just feels like it continues to climb. I've already trashed a rubber centered clutch disc by way of this. I challenge you to produce a dyno run for one of these cars (turbo or N/A, doesn't matter) that shows the horsepower curve start to level off before 7500rpm.

[CPR]

Originally Posted by wild man

I'm going to have to respectfully disagree on all counts. APE DID make a MAF kit that included a 20psi banjo. I have one and so do numerous others, although many of them choose to run lower (like 15-16).

Nize did a test where the ONLY upgrade was the MAF itself - no chips, no increase in boost. The improvement he saw was in the 30-35HP range.

And I don't know where you got the idea that these engines don't like high revs, they love em. I believe you are completely misguided in reference to this. They probably have the best flow characteristics of ANY 8V engine ever produced. They most certainly can, and will, deliver at high end (up to 7500rpm). I've never driven any 8 valve that was anywhere close. And contrary to what you are are saying, these engines are known to have very robust bottom ends.

MY 924S, in which the weltmeister chip allows the revs to go to 7500, has so much HP up there, if you are not looking at the tach when all-out shifting for acceration, you WILL hit the rev limiter, because the power just feels like it continues to climb. I've already trashed a rubber centered clutch disc by way of this. I challenge you to produce a dyno run for one of these cars (turbo or N/A, doesn't matter) that shows the horsepower curve start to level off before 7500rpm.

Hmmm...I'll be near the APE Shop tomorrow afternoon. Maybe they can chime in on this 20PSI "Kit", or offer some clarification to me about it at least. One question though.....How did Nize only test the MAF, without a chipset to decode the signal? The DME cannot read a MAF in stock/Motronic form.....


Moving on.........

If these motors are so stout and so very free flowing, the why are there no tuners that run above 6300~6800rpm? Perhaps one here or there for a dyno, but no reputable shops that I can recall do. Do have any specific names of shops that tune these cars to run in the 7000rpm~8000rpm range? I would be very interested in their logic and to talk to them to see, perhaps, if mine may be better suited for that.

The heads are pretty darn good for their age. But the best flowing 8 valve head of all time? Hmmm....no. The Shelby Dodge heads were in the 190 range, VW had some 8v T heads in the high 180's and then of course there are a ton of SB Chevy, Ford and Mopar hemisphericals that would flow in the upper 190's and into the 200's easy. Remember an 8v head is not limited to a 4 cylinder.....and of course this is not getting into the exotics.....
***for reference the stock 951 8v flows at 180c.****

And finally.......Instead of challenging me to find dynos that are readily available by the hundreds over on RennList, how about you find me one backing up YOUR claim? After all, given you arguement, there must be many that have an 8000rpm dyno? No?


BTW...How long have you had a 951? TIA