Turbo928 update: after 5 months of play time...weeee
 

I've been getting a few emails here/there on how the car's doing.

I have not been under my car (hood or chassis) since I installed the turbo kit May 11 (the day before dyno day). I mostly drive the car to events on the weekends, as there's always something going on in Austin.

I average 17mpg city when shifting conservatively.

The car's temperature runs at about the 1/3 tick, same as stock (I see a longer time to heat up to the 1/3 tick mark now).

I passed emissions with flying colors a few weeks back, both idle and the 2000rpm cruise...with no cats & 30# injectors.

I'm running the Stage 1 928turbosports kit with the following options:
T67 DBB (dual ballbearing) turbocharger, which is water cooled & added to the installation complexity, but worth it. Also, I have the Intimidator exhaust that people hate in photos but love in person: and it sounds incredible! Other than the boost controller conservatively set at 5.5psi, no other changes have been done.

I'll install an intercooler over the fall/winter, just ran out of time this summer...it was hot as hell too.

Markhttp://forums.pelicanparts.com/uploa...1225210725.jpg

...now with Black-centered Fikse's :)


I'll be at ThirdCoast in Mid November for the Sunday show...will be happy to show/give drives, let people drive her....I should have 20,500 miles on her by then!

Do you have any numbers for that emissions test or just pass fail?

i think for idle it was like 68/220, and for 2k cruise it was about 120/220, but I have the paperwork in my car (on the lift). I'll get that for you, haven't forgotten.

Mark

Hi Mark,
I'm new to this forum and am very curious about the turbo idea. Where can I find more info out about the kits cost, install requirements, etc....

Anyone have one on a S4?

Is it as costly as aSC...about the same...or cheaper?

Thanks...new member and learning alot.

Hi Dean,

There are a LOT of Supercharger pushers around for 928's. I used to be one of them, however like many, I wanted to turbocharge the 928 just to be unique.

This is much more difficult to do & only a few have done it. I did it & kitted it, however the market appears so saturated with SC cars that there's just not that much interest in turbocharging the 928. SC's make power, but the delivery is just plain boring to me (My opinion, I'm entitled to state my experiences) by comparison...much like driving a Viper vs a similarly powered 911 turbo.

Go to www.928turbosports.com. This is my site, my kits. I developed them in harmony with boostlogic: World-record holding turbocharger kit builders for the supras (Fastest standing mile, 1/4 mile 6-speed car, 1/4 mile auto with IRS, etc).

I have a few kits left, but once sold, I'm out of the market. I don't make enough $ to make it worth my while. They are a hoot to drive: very exotic as you have all the low end torque, but about the time that things would start to get boring when accelerating on a 928, you're holding on for dear life as you fish-tail up to about 80mph.

They're actually cheaper as they include a full exhaust system. A Base kit is $5300 & includes the wide-band O2 sensor for tuning.

Mark.

Mark - I'm going to ask you a few questions, and if you don't feel like answering, let me know straight:

What is the proper rear mount turbo sizing for a 4.5L and 5.0L 928 engine?

Is it true that with Rear/mid mount systems, the Turbine housing and impeller must be made much smaller to get the most out of the slightly slower and much cooler exhaust stream?

Is it true that opposed to the exhaust side, the compressor side much be very large to deal with the increased volume of tubing going to the engine from the rear?

Baring the debate over water cooled and separate or same oiling systems for the turbo/engine, the turbo requirements seem to be

Single - .60-.80 turbine, and .80 or above compressor
Dual .45 turbine and .60 compressor?

I'm using Precision turbochargers: great warranties, proven, so my nomenclature many not meet Garrett's for example. 4.5l: I was gonna use a T50 or T61 BB turbo, with a p-trim turbine (large) & a .68 or .81 turbine housing. I'd try both turbo's & think the T61 would provide cooler air.

Mid-mount systems: Heat is just one factor, the other is volume. 5.0's making 330hp make a LOT of exhaust volume, esp. in a single 3" system. I use the largest tubine on this mid-sized turbine to ensure there's no excessive back-pressure. My car still breathes freely enough to spin the tires off-idle ala a stock 928, but is boosting before 3k rpm.

Compressore size: the T61 turbine housing is as large as a K27: pretty small. The more area of tubing you have, the more lag you generate, but we're talking 100-200rpms between 2.25" tubing and 2" tubing. NO worries there. Watch my video's on youtube & streetfire: it boosts fast, intercooler or not. Large power supra's have massive IC"s: 5" thick, 30" long, 14" high, and their turbo's have to boost that area as well: it just takes a wee bit more rpm/time to do so, nearly irrelevant on a 5.0 engine using a low-boost turbo set-up for 500-600hp.

I think a 4.5l might benefit from a 50-trim turbo as it will spool a lot faster & hence, more fun. I've seen trucks make 390rwhp on a 50-trim turbo at 12psi on a Toyota tacoma: plenty of juice...considering my healthy 4.5l car dyno'd about 190rwhp.

A dual 60-trim turbo equipped car could have the capacity to make over 1000rwhp: I'd imagine there'd be some lag there...maybe spooling about 4500??

mark

BTW, I'm well aware that some are waiting for more dyno's & such: I'll be back on within a week or two.

Other updates: L-Jet, CIS, & Auto S4 turbo kits: L-jet & CIS kits were never tested as test-cars came/went (local 928er's). I have an S4 auto kit being installed out of the country, so that in itself is time consuming, but I'll update as I hear things -

BTW, I'm well aware that some are waiting for more dyno's & such: I'll be back on within a week or two.

Other updates: L-Jet, CIS, & Auto S4 turbo kits: L-jet & CIS kits were never tested as test-cars came/went (local 928er's). I have an S4 auto kit being installed out of the country, so that in itself is time consuming, but I'll update as I hear things -

Turbine housing - smaller housing, more resistance to air flow?

Ptrim turbine - that would already be matched to the turbine?

mark - check out this ebay ad - 120314779395

Seems like what you describe is not readily available?

the reason that, on the internet at least, people talk about this "master power" turbo, since the sizing seems to fit the program (smaller exhaust housing, bigger compressor:

http://cgi.ebay.com/ebaymotors/Masterpower-60-1-T3-T4-P-trim-turbocharger-ex-a-r-50_W0QQitemZ260238295425QQihZ016QQcategoryZ133202Q QssPageNameZWD1VQQrdZ1QQcmdZViewItemQQ_trksidZp163 8Q2em118Q2el1247

yah or nay?

http://cgi.ebay.com/ebaymotors/GT3071R-BALL-BEARING-TURBO-GT3071-INTERNAL-WASTEGATE_W0QQitemZ110305004334QQihZ001QQcategoryZ 33742QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Anything T3 is for basically, 4cyl engines. T3 is the smallest turbine-section turbochargers available. Mid-size turbochargers are appropriate for street use on most all 6-8cyl cars.

The P-trim is the largest (highest flowing) trim available for the mid-sized turbochargers from Precision: it's a 3" wheel & requires a 3" exhaust minimum. The turbine housing correlates to the power & size of the engine. 500hp-600hp supras usually run a p-trim with a .58 housing. 6-800hp supras usually run a .68 housing. 800+ usually run a .81.

I have a .81 & recommend it as the 928's engine is a 5.0, not a 3.0, and for off-boost flow, the .81 flows more & allows for less back-pressure, both on-off boost. This is also the recommendation from Precision for our cars as well as Boostlogic's tuner, Justin.

I did some detonation testing back in '05, & found a wee bit in the .68 for the 928's running a few other detonation-inducing variables, but none in the .81. I can also feel the engine breathe & rev easier with the.81, much like a stock-exhausted 928.

Mark

Do you think the half liter reduction to 4.5L would make a difference with your .81 recommendation?

http://cgi.ebay.com/ebaymotors/t4-62-1-ar-70-compressor-ar-68-turbine-turbo-charger_W0QQitemZ310095050002QQihZ021QQcategoryZ33 742QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

?

for a 4.5l , I'd probably try a .68 first. If I thought it were lazy, I might try a .58.

Keep in mind a 4.5l 928 makes about 2/3 the hp as a 5.0 32v car.

That turbo states a 2.5" outlet: that's very small: enough for a 4cyl, but prob. too small for a boost 6, let alone an 8cyl..

I can correlate with Precision's turbos, but am not savvy with other makers/nomenclature. I am by no means a turbo expert, I just know what works well on a 5.0 928. :)

Did you see the master power turbo

This 3.5L V6 gets a T04E:

http://www.zimbio.com/All+World+Automotive/articles/2145/FS+STS+rear+mount+turbo+kit+G35+Sedan

Brendan,

You have to first pick the compressor for the engine size and then focus on the turbine. Yes...the turbine and housing for a rear mount are typically smaller than front...this aids in getting them to spool since the air has lost some temp (i.e. energy) from the heads to the back of the car. Remember, it is the heat and pressure differential driving the wheels...not just pressure as some people believe. You can measure temp drop across a turbo...that heat went into powering the compressor.

Rule of thumb...a turbo sized for front mount if mounted at the rear would be very lazy to come on boost. The air loses some temp and pulse energy at the rear, so to compensate you size the turbine and a/r down. Lots more to turbine sizing than a/r though....many turbines, housings and a/r ratios in those housings. Not an exact science either.

JK

Well, I appreciate your input. But I am finding it hard to find specifics wrt spool time, and actual hot side and cold side turbo sizing for a 4.5L.

I emailed the people that actually do the rear mount turbos on the S4, but I received no response. Not that I thought I would.

The entire dynasty of rear mount turbos is based on keeping the trial and error of sizing at the rear secret.

I also appreciate Mark telling me his thoughts.

Spooling by 3000 is fine by me. Not running out of steam until 6500 is also important. But honestly, I won't do this unless I can keep the price down VERY low. Because if it gets expensive, I will just do a SC. Its just too easy.

But the rear mount turbo idea sounds interesting, and for what it may cost, a good deal.

No Cat should make the turbo spool quicker, and leave more heat in the air. I don't know if I would want to put it infront of the trans, or further back where the muffler goes.

I think I need to learn how to weld like this:
http://www.iwsti.com/forums/off-topic/137191-rear-mount-turbo-porn-56k-you-will-here-month.html

So a single turbo on a 4.5L should be quite big. Like 96 or so, right?

Mark,
I have a turbo and intercooler.... I need your exhaust plumbing.... PM a cost. Also, I sent Jeff, then you an offer for some drivetrain components at his request. Never heard a peep....:confused:

There is no magic here....you just have to size one and try it. I would go one size down on the turbine compared to front mount and then try a couple of a/r ratios on that. I would stay far, far away from any turbo that is an off brand name....they are bad news. I only use Garrett. I have 17,000 miles on my system now and have not heard a peep from either turbo...they are reliable pieces. You put a Chinese turbo on the car and you'll be having issues with it...it's not worth the risk.

I know you are right about the chinese thing. The power master seems like a quality unit.

I was hoping to find a BB one that was used.

Get a used K27 for the rear. Maybe not the optimum, but for a couple hundreded dollars, your in business and making doo power. A K27 should support up to 550HP. If it ws good enough for Porsche, it's good enough for me. Blow the turbo, just buy another K27..

Of course this advice is only for those of us on the DIY budget..

What size is a K27?

You can get the K27 with T3 flanges to make hook up easier. K27 is the big brother to the k26 that came on the 944turbo. Someday when I get all the parts to go turbo, I'm going with a pair of these. $500 for a pair, even if they only last a year... A bit more oldschool design, but still effective. No ball bearings etc..

http://www.sakuraindustry.com/osc/im...tang_K27_1.JPG
http://www.sakuraindustry.com/osc/im...tang_K27_2.JPG
INLET 2.75"
OUTLET 2.75"
BEARING TYPE WET FLOAT BEARINGS/oil cool
OIL INLET 1/8 NPT
MAX PSI CAPACITY 35PSI
COMPRESSOR 63 AR
INDUCER 49.15mm
Exducer 80.84
Trim 36.9
Turbine .87 AR
Inducer 67.16mm
Exducer 75.85mm
Trim 78.4
FLANGE TYPE T3 FLANGE
DOWN PIPE FLANGE TYPE 6 BOLT STANDARD
MAX HP 550hp

You'll have to go twin to not choke the exhaust on a 928: All K26's and probably all K27's are sized for 3.6 (rare) & smaller engines. The backpressure would cause major detonation issues I'd bet.

Agreed: skip the cheaper Chinese turbo's: go with a used Garrett or Precision before you go with a new Chinese turbo.

EMission testing results
 

Ok, here's my emission-testing numbers:

For 2400 running test:
HC 36 out of 220 (which is the max. allowed)
CO .38 out of 1.20

For idle, 705rpm:
HC 140 out of 220
CO .66 out of 1.20

30# injectors, stock fuel pressure yet an SMT-6 to pull back during cruise & idle.

My maps are set for about 15.0-15.3 Air-fuel, though my O2 pulls back to below 14.7 attempting to correct to 14.7. I get a slight hunt at idle like this, it likes to be at or just below 15.0 to remove any idle hunting.

Boostlogic routinely sets their cars in the mid 13's for idle, but many of these are mostly off-road Supras.

Why are the boost levels kept so low? 5-7psi? Ricers are hitting 25psi on stock bottom ends. I'd think we could hit 15psi safely.

compression amigo, compression

Engine management, complete fuel systems, expense, etc.

Not buying it. Many Hondas have higer compression yet boost like crazy. Meth injection would allow for more boost with out detonation or retarding timing as much.

I would be one of those people! SmileWavy

The higher the boost the fewer good parts are left when the air fuel mix etc goes boom. Some racers are happy with 30 1/4 miles passes between booms.

Ethanol removes all those BOOM problems. Nearly completely.

Most of those high boost Hondas have firering head gasket, aftermarket head studs and cast iron blocks. For longevity, I would stick with 7 psi or less. I am running 1 bar boost on my otherwise stock 931 and have realized a rebuild every 3 years.

Dennis

Agreed. A simple water injection or meth injection cures the detonation issues. Only issue is when the meth tank is empty you have to dial the boost back. I have run up to 250RWHP of N2O with meth injection and 6* retard on timing with no isses. Of course not with the frequency I would be using boost on a turbo..

He said ethanol not methanol.