Robby

Matt- are you SURE a K26 can flow a FULL BAR of boost ALL the way to REDLINE? I remember the EC article w/Cervelli & Raines stating that it absoultely could not- this was in '97 IIRC- But, K27's could flow more than half again the air...so, COULD hold a full bar past redline... Anywayu, since that article, I've heard it from others, far more times than I could count- sure, a 20yr old wastegate wont help matters, but, it wouldn't matter much even if it were new unless it were modded, since it was designed to screw us out of low end...

OH, I also agree w/you that our lag is not THAT bad, but, it depends on what yo're wanting to do w/the car - if AutoX, then, it IS that bad... The Turbo S is much worse- the Turbo gets full boost & max TQ @ 3500rpms & Turbo S @ 4000rpms- tha'ts a good dif. Of course, we've all seen tuned examples get full boost by 3000K w/out trouble, so, it can be done... 3K sounds fine to me, but, consier newer cars, like S4's getting full boost & TQ by 1750.... it's no comparison, although I question the need for a street car- but, it IS kind of cool...

I agree about the disp & have said this myself for years- not sure a 2.6L would REALLY be such an improvement over the 2490cc... BUT, the 2.8L w/968 stroker cranks WOULD.... THAT would be the ticket to low-end, even w/out a second turbo... anyway, it doesn't much matter in the end b/c we are not the ones doing it.... fun to pitch out our ideas, but, the man who makes the call hass other ideas & MAY in fact work as well, OR better.... who knows... in any event, I'm looking forwward to seeing the outcome...

As for 928's getting TT's- I KNEW their 8cyl's did not need the extra low-end- always wondered WHY they had the TT (Callaway, etc) anyway....

Also- the RX7's you've built... what kind of HP/TQ were you getting w/the single turbos? What kind of reliability? I always wanted the TTRX7- I loved those cars- I'm sick of pop-up headlights now though... Can't see EVER finding a way to delete them on my 951 (or 968) b/c I think the car would NEVER look NEARLY as good w/.out them- would need a complete front end re-work... NOT for me... Does anyone know if the roll-forward, pop-up headlights in the 968 used the same mechanical parts to raise & lower them? Was it just mounted backwards or something? Any info would be appreciate here...

Danno

Robby, the dropping boost in these cars has to do with the crude boost-control mechanism. Replacing with an even more primitive mechanical controller doesn't help (aside from raising mid-range max-boost levels). I've always been a fan of electronic controllers (80% of ricers go for EBC right off the bat), and eventually the 20% of 951 owners who want flat boost will go with an EBC. Using an electronic controller is the ONLY way I've been able to hold flat boost with a K26/6. I've even programmed in a rising boost-curve 15psi in the mid-range to 18psi at redline to compensate for the dropping boost-curve. Or even a 18psi flat curve if I wanted. Max-HP only went from 260 to 270rwhp with the increase from 15 -> 18psi, most likely due to the turbo being maxed out and out of its effeciency range, but mid-range torque saw a healthy 40lb-ft increase.

One also have to distinguish between turbo-lag and boost-lag, you guys are getting these terms mixed up. Boost-lag is the shape of the full-throttle boost-curve. If you start flooring it at 2000rpm on the road or on the dyno, you'll eventually get max-boost say... 15psi... by 2500-2750rpm with the K26/6. Boost-lag is RPM-dependent..

Turbo lag is a time-dependent value. Say, you're crusing down the road and a flies up the inside and cuts you off. You floor it to spank him and count 1...2...3..4...5 before WHOOooshh, you get boost. That time you're counting is the time it takes to go from zero boost (or vacuum) under cruising, to the max-boost-level possible at that RPM. This can take anywhere from 0.25-0.50s and isn't too noticeable under most circumstances, but each of those half-seconds adds up on something like an autocross, where an S2 or 968 with instant power coming out of a corner will demolish a 951.

BTW - a 959 is 2849cc

Robby

Danno.....

what the hell is that sign in your sig? Does it say "Comcast" & "windows XP" for everyone or does it vary by who's reading it?

Full boost (15psi) by 2500-2700rpms on a K26#6? You are obviously doing something to the wastegate, etc, aren't you? What EBC do you like to use? You & I have talked a lot about A:F ratios... I was under the impression that using an EBC to program multiple boost settings, would not work- EX: low @ 10lbs (for wet roads, etc), mid @ 14lbs (for normal driving), & high @ 18lbs (for showing tailights to muscle cars) that the A:F ratios would NOT be correct on all levels & taking a chance of ruining the engine- is this not true? Can an EBC change the amount of fuel one gets at dif boost levels- how? I mean, what does it connect to anyway? Where does it get it's signals from & WHAT does it connect to to increase the boost &/or control IT- wastegate?

Also, What do you think about aftermarket wastegates, for someone like me who want's simplicity, long-term reliabilty, & some 350RWHP/TQ? Would modding the stock wastegate work &/or be as effective in the end? Is it easy to program? What about stand alone- if I had that, would I still need EBC? I know that stand alone allows one to eliminate several things, which makes it sounds like a decent deal in the end- do you know if stand alone is a simple, reliable way to go for a street car?

thanks....

Chris_924s

Danno's sig will show you YOUR IP/ provider status,OS and browser (However Avant is emulated as IE6..) . It's cute..

Robby

I see...... hmmm.... still don't understand the IE 6 part, but.... ok.... I now understand the rest of it... .interesting.... I ALSO noticed someone else w/one of those little things... showing me my ISP, etc...

kennycoulter

i say use the holset. is the garret t03 better than the kkk's? arent they a bigger housing atleast? im putting 22 psi to my svo and its on the stock tc intercooler......over top of the exhaust, so that should mean its a little bit efficient right? the t03 is on the earlier merkurs and earlier t-coupes. maening 86 and down......anyway, in one of my mustang magazines, there was a new product that had the idea of the j.c. whitney type of exhaust cutout that you can open to mufflers, or open to no mufflers for racing......but it was electronically controlled to work on the fly. maybe you could do that and be simpler have it half open for your switch from the smaller to the larger turbo. and if you go with the ihi, they were 18 psi on the "premium" stock ford bcs for the 87-88 turbo coupes.....and are a smaller turbo to be able to get the low rpm power. do you still have ac? i would have the stock i.c.s in the stock location, and then have another stock i.c. in the lower opening. when i forst got my 944, i wanted to swap to a 928 engine and have tt, i wanted to mount the intercoolers behind the front wheels, and vent them out in front of the doors. if you do want to try a supercharger, i can start asking people on the cobra forums if they are willing to sell their stock supercharger if they already swithed to an aftermarket one. im in no way smart enough to know stuff, im only saying stuff that i know very little of and hope i am helping in the process. i believe that not enough 944s are hotrodded.

Danno

Robby, I use the Apexi AVC-R and programmed it similar to Rage2's and .... ... someone else's setting. Basically I program in maximum-boost 100% duty-cycle from 0-2500rpm to keep the wastegate fully shut, then taper it down to actual boost-levels from then on. Each gear has its own duty-cycle curve as well so that I can get identical boost in each gear if I wanted. But I actually had 1st & 2nd set with slower build-up of boost from 2500-4000rpm to function as traction control. In 4th & 5th, I can pretty much get 15psi by 2000rpm. That was on my previous car, I've still got an AVC-R in a box to install on my current car.

I think intelligent electronic controls can completely transform the nature of a car. Going from the original bone-stock 951 to one with manual control to EBC created 3 very distinct cars in terms of behavior. The stock one was very mild, felt just like an NA with large displacement. The manual-controlled one with extra boost was the most frustrating due to the lag. The last incarnation was nirvana! The EBC really "woke up" the car, made it more responsive, quick, it felt lighter!

nine-44

I'm actually running an Audi 5000 WG, dual port and I did the adjustable mod also. The valve may prove to be too small for this application and cause boost creep?

Danno

It's the spring that does the creep, not the valve-size. Use a hand-held pressure-pump to test it, I use the syringe type of pump that's used to pump up motorcycle forks. Has a neat little 0-25psi gauge on the end, just hack off the shraeder-valve fitting. Push the bare hose over the nipple on the wastegate's pressure port and pump. Ideally, you want the wastegate to start creeping open about 2psi under your desired boost-level. If not, replace the spring with a stiffer one.

Another thing is that you don't need a big wastegate valve. The higher the power-level, the more you're trying to squeeze every last bit of boost from your turbos, the less exhaust the wastegate has to dump, In fact, on a lot of the turbo drag Hondas, they have no wastegates at all, they just let the turbo free-rev and cram as much air through the engine as possible. They hit 40-45psi in the mid-range and drops to 10-15psi by redline.

xsboost90

i guess if you compare hp levels to the amt of boost you are running, then the k26 will not flow enough, but boost does not always = hp. Sometimes, if done right, you can make more power with just a small amt of boost, which, if brought on faster, will help low end hp. The key is efficiency of the boost you have. If your running 26lbs of hot air through a small intercooler, then it really isnt much better than 15lbs through a good intercooler. In my experience, the guys with the big hp are running 18lbs with a highly efficient system.

Danno

Don't forget he's got two turbos... The 959 had twin K24 turbos and was good for +400hp. Same thing with the 993tt. Canepa on his US-spec conversion of the 959 adds twin K26s for 600hp+. The 962 had twin K26s for 600hp+. A lot of 993tt guys upgrade to twin K26s..

To come up with the combined flow-rates, just draw a graph of CFM flow vs. RPM for each turbo. Then add the two curves together.

nine-44

Sorry about the boost creep mixup, I mean running out of flow to regulate boost and overboosting. Danno, what you are saying is still 300 HP max through a K-26 each. That was about my take on them, I still wouldn't want to push to 350hp, #6 or#8. I'm thinking that expecting about 175-250hp per turbo will keep me in their efficiency range pretty nice and pushing less hot air.

Rock

My theory is that the K26 boost pressure will reach a climax of 22PSI at 11 bar when the moon is at a wanning gibbous. A full moon will cause the refractory rate of the light trajectory to, in theory, become unstable. Thus causing the prism crystals of the 959's V-22 turbo setup to ignite, which may lead to extreme piston aggrivation while travling to the grocery store. Now, if we were to use a K27 with a vaccuum cleaner motor in place of turbo number one, we could then create a radial hexogonal pixel difibulation. This would create enough pressure to cause the engine to run at optimum boost while performing at maximum reliablity. The formula for this is simple...

X= Boost at turbo #1 at 3500 RPMS
Y= Boost at turbo #2 at 3500 RPMS

We will be searching for "B"

X+Y / .5 x 22PSI + 944 -951 x 959Turbo = (3.14x2)

So lets figure this. at 3500rpms we will be running these numbers.

14 + .0123 / .5 x 22PSI +944 -951 x 959turbo = B(3.14x2) then for good measure, multiply it by the number of hours i have played diablo 2.

The final number is 3.3415 Billion. Andy will have 3.3415 billion PSI into cylinder number one at idle. Thus proving, that turbo cars do not exist, but are rather, a figment of our imaginations.

Danno

The answer's actually 42...

TaylorSea4

Now THAT is funny, man...

Andy, I'm not gonna nay-say it cuz I know you'll do it anyway. But I DO see the point Matt was trying to make. There ARE cheaper, easier ways to make 400+ hp WITH drivability to boot. But then, that would go against the hot-rodder's spirit that burns so brightly inside of you (or is that the microwavable burrito you had for lunch??). Hell you may surprise even yourself and end up with a 500hp beastoid creation that will land you a covetted spot with Andial's R&D department.