What's Your Boost Setup & Curve
 

What’s your forced induction set up, boost curve and how do you like it. Mine is 3.0 liter w/ twin K24 18G turbos. Comp. Ratio 8.9:1 RPM/BOOST/ : 3K/1.6, 4K/3.5,5K/9.3,6K/15.1,6.6K/19.2. This set up works for me because I think it’s easier on everything and fast 60-130 which is my driving style. Maybe a shot of NOS later for down low.

swap out those turbos.

Well taken! Any suggestions?

I don't know much about the k series little turbos but I think there is a k16? I'm sure you could get 19 psi but sooner. 3.0 is smaller than the 3.6 the k24 was designed for. I have a 3.0 930 and use a single gt30r. My aspect ratio is the .82 but I want to swap to the .63 so I get boost quicker. I see .8 bar by 3200rpm and it holds all the way to 6000rpm where my cams are done. if I wanted to raise the boost, this turbo is good for 525hp.

I'd like to see your intercooler.

OK, you're saying 19.2psi with a fixed compression of 8.9:1?
When you rebuild your engine use a pair of K16s.

We need pictures of that engine!
K16 should be a better fit for 3.0L displacement.
If I were to "map" boost I would assure full boost was available in the meat of the torque curve and drop it off a touch after 6000rpm. There is no advantage in having twin turbos if early spool and torque are missing.
The figures you quote should be a time bomb on pump gas. Is some info missing? Engine management system? Octane enhancers?

K24 18G is a modified GT2 turbo with Mitsubishi 18G compressor wheel and is a popular upgrade to the 996tt stock turbo. The K16 could be a very good and better fit but may be somewhat limitng at 525HP. The K24 has a large 1.0 A/R. I knew going in the turbo was large for my engine but being a hand-me-down from my son modified 996tt I thought I would give them a try. Checking the stock K24 turbo map at the pressure ratio I was looking for it was right in the sweet spot. It is very efficient at 19psi and that coupled with max boost being above max torque lets the engine live better at 8.9:1 CR. The car runs like a stock 930 on steroids with less lag and while not ideal I must say there is a fun factor in that. Like that big flat curve from 3K.

Here's the intercooler.http://forums.pelicanparts.com/uploa...1342121429.jpg

I totally agree with you and like your mapping plan. But if we think out of the box for a minute the top end power of the K24 18G set up is great and efficient. I don’t think you can beat it up top The K16 being smaller will probably create a much more heat up top at high boost and may result in being boost limiting considering the high CR. Water/meth will help. Is the use nitrous completely off the table? I can envision properly controlled nitrous for this setup turning on at say 3K and off at 4800 and then we having the best of both quick spool and power. Time bomb??? Maybe so. I can only say that it has had many dyno pulls and runs great at that boost and CR. The engine management is Haltec E11V2. Would you vote for trying nitrous or K16?

K16! The reason is the same reason some here choose intercooling instead of water/meth as their cooling agent for the charge. You never run out of it. I chose to use intercooling even though I bought a meth system and now see the reason, as I have come close to running out of water in the tank.
If you use nitrous, while it seems like the easy fix to your boost issue, you'll run out at some point, If you change to the smaller k16 turbos, or even go the single turbo and use a more user friendly metrhod to boosting, you'll love the much more streetable power available. And if you want to rev, go ahead and rev to 6600rpm, but start boosting sooner, that will give you more boost time and much more usable power.

Peculiar set up!

How is its streetability and reliability?

Is that a modified stock 930 intercooler? Looks like it..
I don't believe your 466 wheel horsepower because thats well over 500 HP st the crank and I don't think you can get enough CFM of air through that intercooler core to make that much HP from 3 liters, and the air coming out of that thing is going to be hot.

I'm sure it's fun to drive anyway.

One of the reasons I would reduce boost above 6000rpm is to allow the K16 twins to remain efficient. Max HP is not of interest to me but may be to you so this is personal preference.
For the same reason I am not a fan of relying on injection of nitrous or MeOH to produce power. Great if you have engine control systems that can change all the tuning parameters when injecting combustion enhancers then switch them back when they run dry or are not used.
I quess the real question is what are your goals with this engine?

Whats the exhaust look like?

Thanks for your comments. I can see where you might doubt these numbers but I assure you they are correct. You are absolutely right this is a modified 930 intercooler. Remember this is a rather small intercooler and not too many tubes for restriction. Intake air temperatures run about 140 F at full boost which is think is pretty darn good. Air pressure loss across the IC is about 2-3 PSI. Being from Texas A/C was of prime importance and the way the custom intake tube routes sacrifices had to be made in the engine bay. Think about a 3.0 liter Supra make over 1000 hp. It all in the flow of the turbo and this engine is capable of well over 500whp and the K24 18g turbos are capable of supporting about 700 hp. The boost control map is set at 19 psi and the electronic controller kicks in at about 5800k regulating the wastegates. So there is plenty of air left. I guess I’m more interested in mechanicals and not too concerned about the looks of the engine bay. Maybe that had some influence on your thinking. Sorry for being so wordy and hope this helps.

I'm no expert, but even I can see where things can be inproved. Starting with the intercooler, that is too small and ineficient for high flow and boost. Those are good for low boost and even then proven not so good. In the stock location, it had air pulled through it by the fan and a good shroud, yours is farther back and probably doesn't get quite enough airflow through it. The turbos are good but not for your application, you would do much better with smaller turbos or only one of them, though it would not be quite enough for 400 hp. But two k16's might be great though probably still too big for my tastes. If I were you, I'd get either the k16's to reduce modifications, or make up a single turbo system with a nice common and proven turbo for your application that will make a great street car. Your setup would be fine for race situations maybe, but even still probably be better with a smaller turbo even then. And with a much better intercooler. I'd bet your getting detonation with prolonged high rpm and boost runs with that setup. Thats why the timebomb comment. With your high compression, you need a small turbo and lower boost. If you did that, you'd have a faster safer car. Maybe not quite as big a rush but the final result would be a faster better driving car.

What transaxle are you running?

So far, I like everything you've done! I believe Brian is on to something...915 tranaxle? He can tell you more about those than me...

I say keep it like it is if you like it!, I love the low end "grunt" these other guys are talking about, but I don't think it's a good idea to move the boost curve lower in the RPM range in YOUR case...

You did say Texas right? Hot, but lots of open road where you can always have ALOT of air moving through the engine compartment, probably why your intercooler works fine

The lower back pressure of the larger turbos is probably a good thing, again, in YOUR case.

I'm currently obssesing over a low cost, franken-porsche monster built from hand-me-downs and pieces cast away or collected at low cost where the availability of parts sorta dictactes the build, prolly why I like your "hand me down turbos" so much :)

...so far I have a 993 Transaxle and an M64 RS flywheel, quite A LONG way to go...

Your statement says it all "60-130mph"

996tt- Guys are still using them and upgraded to a billet prop. Then they want more power they go with a meth system or e85. They are showing OVER 600WHP easily...I would leave it...U will eventually break something if the internals aren't beefed up.

Be careful if u have a 915.

Want boost sooner, upgrade the headers :)

I guess too much is never enough. :) :) :)


Walt

Some observations that may change the entire board's beliefs and other interesting facts:

1. > 19 lbs of boost on a high compression motor. Wow.
2. Small intercooler running high hp with high air temps on a high CR motor. Wow.
3. Twin turbo - 'nuff said. Very few 911's have this.
4. Huge hp numbers from a small motor and high IC air temps.
5. Large twins used for efficiency (heat output wise), not concerned with lag.

Just for reference, on a near 100 degree day, I have only seen 114 degrees from my IC running through the gears peak.

I'm assuming this engine made the huge numbers due to the high boost, high static compression ratio, and high RPM?

Those hp numbers are huge and impressive from a 3.0L.

You are a sort of pioneer I'd imagine. :)

To answer your original question, I'd say if I nail 4th, I will get a tad of boost nearly instantly, maybe <0.1 bar for a split-second and then it slowly creeps to a full 1.0 bar by 4K or more.

I have to ask, are there any dyno charts/readouts to show your curve or figures?

Brian asked a very good question that I had to stop and really think about “What Are Your goals For the Engine”? I guess I would have to answer it with a different question “Will the Car Pass My Want TO Drive Test? That test is simply: When I come home from work would I miss dinner to take a 75 mile pleasure ride? I must say in stock trim the cover would never come off the car. But with the k24 18G setup I’ve done that many times. To me that is a true hobby car and I tinker and experiment all the time. IT”S MY HOBBY! A 996tt or 9997tt would not pass the test. So yes I’m going to keep my current set up and experiment with nitrous for down low in an attempt to create a more awesome machine that maybe I’ll miss dinner a couple more evenings a month to drive. That being said I do want to have an alternate milder set up that I can convert to in about a half day. If ”Turbo Powa” would be so kind to give me his single turbo set up I would like to duplicate it.... that fat curve from 3K to 6K really sticks in my mind. Maybe that will pass the test and I’ll keep the big power for speed events and modern muscle.
About a month ago I converted the 915 to 930 trans and kept the 915 transaxles. I don’t think the transaxles will be a problem with my current set up but when I start putting the power down low around max torque they very well may become an issue. The engine is built pretty well for boost with JE Pistons, ARP rod /head bolts. I am running 1 ¾” headers (1-5/8” I.D.) I tried 1 3/8 I.D. but the engine started missing due to excessive backpressure.

Sounds good ^^^^^^^ :)

No dropping the clutch Eddie Bello...and u will be fine. :)

I do. Will have it scanned and then will post it

If you have that 930 box I wouldn't worry, wish I had one so I could turn up the boost.
Well, my setup is in some ways not as good as yours, and other ways better. I say better and some might not agree because I have 6.5 to 1 compression! But I love knowing my engine is in no way over stressed. If I had a 930 box I could run lots higher boost and my turbo (gt30r) could provide lots of it.
I installed headers hoping to reduce boost time onset but only got 200rpm difference. Not sure if it's the good turbo or bad obx headers that keep me from getting a larger difference. I have a garrettson Intercooler and I use water meth injection to keep things even cooler though I really don't need it. If I were you I'd use it though. So my system isn't earth shaking, it's very normal. In fact it's very subtle compared to most guys here. But I still think when the time presents itself you'd really love the quicker response of at least one size smaller turbo.

O and I only have cis and use msd for ignition. nothing special.

I would say the engine made the numbers because of high boost,rpm, tuned properly and was real happy with the turbos and 964 cams. It was in its sweet zone up top and I believe it would have easily made well over 500whp if pushed it a little more. I do my own tuning and there are certain areas that are very important. Naturally A/F but proper timing over the upper RPM range is crucial to real power. I tune for max torque through the RPM range. Since the engine hasn’t shown any signs of detonation, the recorded 140F IAT is not really an issue to me and would consider it rather low on the improvement list.
What’s your set up? Very Impressive!

Let me say up front I think the guys on this board are great, knowledgeable and very helpful. But I think in some ways many are stuck in the eighties and not open minded for possible alternative ways to modify our cars for maybe even more enjoyment. I never believed the early cars were designed to be launched hard and beat on down low like say american muscle. What good is 400 HP at 3k in a car you can’t shift? Do you really want to try compete with cars that can? Today its about what I call modern power. Modern power is cars that are built to compete at high speed 60-130, ½ mile and 1 mile runs and that requires a different approach. I think our cars can hold their own in this arena if built right and still would be a lot of fun to drive. I know its not “Streetable” but I say lets work on that. There will always be the stop light to stop light guys and that’s great if that’s what they enjoy. But I believe there could be another segment that would enjoy modern power. Now I’ve said it have fun with it.