Corleone

Yes, I think its a very good choise if your goal is around 400-425 hp.

Here in Sweden we have 2 different guys that has dynoed their 3 Liters. One with a K27/10 and one with a KX700 a combination from K27/K29 and both of them had about 430 hp and 600 nm. This with ported head, camshaft, exhaust and every other things around. They boost about 1,35 bar (19,5 psi) falling to 1,2 bar (17 psi) at redline and 6500 rpm.

With this you can see that its not neccesary to have any bigger turbo than a 3071 if you dont will do the bottom with other rods and pistons and go for higher power. With this you is going to have boost very early, instantly and with a tremendous torque. This will do the car fast at the street.

Corleone

Here is my engine mount!

mrfixit951

J chen,

I appreciate your help. Notice that on the pagparts site their are two GT turbo listings. One is the true Garrett GT series as listed in the catalog. The second GT being listed are being manufactured by Precision. This is the same Precision that I am have been talking too over the phone. Pagparts is a reseller of Precision tubos. Precision being a Garrett distributor cannot undercut pagparts price. Precision turbo is one of the two USA based performance distributors, and less than a two hours drive from my house should problems occur.

My previous posts were not clear, the GT 4 bolt 100mm spacing discharge cover is what matchs up to our downpipe. The T3 size flange is on the turbine inlet type only. My plan was too use the external wastegated turbo in the 0.78 A/R exhaust as listed in the Garrett Catalog. Unfortunately after speaking with Precision turbo again this morning, the GT32 external wastegate does not come with the 4 bolt 100mm spacing of the GT30 turbo.

He could not find the part number for the Garrett cast (not turbonetics) KKK compatible turbine housing that many of the tuners are using.

Ben

J Chen

Nice work Corleone, I see that you did not
have to cut down the height of the engine
mount that much. Unlike mine because my
manifold is stock not to mention that the
TO4S housing is much bigger than the TO4E

J Chen

mrfixit,
0.78 AR for the hot housing is way too big
for the 2.5 engine. Better to go with 0.4 or
0.6 something AR if you can get one. Failing
to do so, I would advice you to scrape the idea
of using the GT32. It's gonna be too laggy.

Edman951

Here the GT32 map.


Not the best match for fast spoolup
I agree with JChen, you should scrap the gt32 idea.

I suggest if you go full Garrett get the GT3071R
Because if you are going to go trow the trubble of making a custom tubo setup.
Get the best turbo out their. But if you want an easy over the week end install. Get a turbo from one of the tuners.
check out this map of the GT3071R
First spot 3000rpm 15psi
2- 3500rpm 20psi
3- 4000 rpm 20spi
4- 5500 rpm 20psi
5- 6500 rpm 20psi



Check out this T04E super 50trim.
This would make a great turbo


You could get this turbo from turbonetics with a stg 3 turbine wheel with the replica KKK housing.
Or you could get a standard T04E 50trim fully built by TEC.
Rage used to have this turbo, he made mad power with it.
Here a T04E 50 trim at 15psi

TurboTim

We make a crossover that will allow you to bolt up a GT series turbos.In fact we have all the stuff that will allow you to bolt on a GT series turbo onto your 951 including a special mod we do to the bearing housing which makes it compatable with the 951 turbo mount.We have a new oil line for it and the downpipe for that matter.We are going to be selling this set-up as a complete package for those that are interested.We reccomend the GT28, GT30/R for street use and the GT35/R can be used for race cars that can tolerate a little lag in trade for big power.

J Chen

Hi Edman,
Is this calculator accurate. I wonder what
method Tony G base his calculations on.
If you use the map of the 60-1 on your
calculator, I'm sure it will not turn out
to be the same. Can you give it a go ?

mrfixit951

Edman951,

Thank you for all of those maps. My calculations at 3000RPM with a VE of 87% yielded an operating point a little to the right of the surge line. I skipped over the 3500 RPM point, and jumped right to 4000, then to 6500. Thanks again for checking this out. I felt that the Gt30 with the 76mm Comp. wheel was a little to large. This is the first map I have seen of the GR3071 and I agree that it looks awesome. I will have to check pricing... This is not going to be a weekend install.

Edman - so you are suggesting a 0.6 A/R on the exhaust side?

J Chen - What A/R are you running with your GT25R?

Dark Lightning

Granted the following comments should be taken with a grain of salt since I'm discussing results on a different motor, but the theory still stands.

[soapbox]

I've owned several turbo Eagle Talons (same as Mitsubishi Eclipse), engine code "4G63": 2.0 liter 16 valve dual overhead cam motor with ~41# (450cc @ 43.5 psi) injectors and all wheel drive. The stock 4G63 turbo's performance is comparable to a 951's with a bit less torque: 205 bhp, 205 ft/lbs, 7200 revlmt, and a turbo that runs out of steam at 15 psi (1.0 bar). Standing 1/4 mile in stock form yields about a 15.0 @ 100 mph.

My work: Intercooler was upgraded to a 28" x 10.5" x 3" front-mounted unit. The intake cam I upgraded to a 264 degree HKS cam, the exhaust cam to a 272 degree HKS cam, Crower springs and titanium retainers, stock valves, 9000 rpm revlmt. Exhaust was upgraded to 3" from the turbo to the tailpipe, no catalytic converter, stock cast iron exhaust manifold (ported though). Fuel injectors were upgraded to ~64# (720cc), fuel pump was upgraded to 290 liters/hour. Fuel management was done with a standalone unit, programmable on the fly via a Palm Pilot or laptop computer. Stock block, pistons, rods, crank, non-ported head.

My choice of turbo was identical to that of Edman951: "GT30-12", 56-1 trim, but on a 2.0 liter. "That turbo is too big for street use." Heh, you should have rode in it. Anyway, I only ran the car on straight 93 octane pumpgas. No race gas, no aviation fuel, no octane boosters, no water/alcohol injection, no other fuel additives.

My results: I ran about 25-26 psi (1.8 bar) with full boost by 4000 rpm or a bit more. This car was driven daily at these boost levels for two years and after a lot of nagging from my friends I took it to Milan Dragway. Best run was 11.918 @ 113 mph with a full interior (back seat, bag of tools, laptop, etc.) and half a tank of gas.

"But a stock motor can't take it." Yes it can, you just have to do it right.

If you autocross your car, this probably isn’t the mod for you. But if you road race, drag race, or street race your car, give this some thought: build up your car as if you're going to make a 35 psi (2.4 bar), but only run maybe 22 psi (1.5 bar.) Upgrade the intercooler, install hard intercooler piping, get a good exhaust, buy the largest reasonable fuel injectors, etc. But most important is the turbo: get something bigger than anyone else recommends and slap it on your car.

Fast and cheap turbo theory: individual turbos have the ability to 'push' a certain mass of air, typically measured in pounds of air per minute or some similar unit measure. As you approach the turbo's limit, the temperature of the air being compressed goes up. It's not unusual for a stock turbo at low boost levels to generate 7-8 psi (0.5 bar) and air temperatures near 200*F (95*C) at the compressor outlet. This is why we have intercoolers so that the air mixing with the fuel and entering the motor is sufficiently cool to prevent preignition or detonation. Take that same turbo, run 15 psi (1.0 bar), and you could easily see 300*F (150*C) air temperatures at the compressor outlet. Sure the intercooler will lower those temperatures, but not as low as we'd like.

See, higher air temperatures = greater air volume = less air mass. Less air mass, less power. Lower air temperatures, more air mass, more power.

This is why if you run a GT30-equipped 951 at stock boost levels will make more power than an identical 951 with a stock turbo at stock boost levels. Cooler air is denser air, denser air has more oxygen molecules (among others), and with the appropriate amount of fuel will make more power. But if you’re installing a $1200 turbo are you really going to run stock boost? Oh hell no.

But let’s say you want to 22 psi (1.5 bar) on the street. Do you look for a turbo that maxes out at 22-24 psi? No. Why? Because we aren’t any better than we were before: we have a turbo running at or near its maximum airflow, which we already know will produce higher air temperatures than we’d like. No, we want a big turbo such as a GT35R or *gasp* bigger. Such a turbo would push 20 psi easily at low air temperatures. This (with proper tuning) would help eliminate detonation while providing very good power.

“But it’ll spool slow.” Not too terribly bad. Sure my Talon didn’t spool until 4000 but it was only 2 liters and the 9000 rev limit helped. Until you drive a big turbo car don’t bitch about the lag. :P

“But the transaxle won’t take it.” See, this is where turbo lag and driver judgment come into play. A fast spooling turbo gives you neck snapping, axle snapping, and transaxle snapping power. The slightly longer lag means the power rolls on gentler. The Eagle Talons are famous for their glass-jawed transmissions and mine held up rather well. Driver judgment helps when 4000 rpm clutch drops are kept to a minimum.

[/soapbox]

Just my $.02, your mileage may vary, yada yada. If you don't believe my theories, that's fine, my feelings won't be hurt.

I personally plan on a GT35R or larger for my street-driven 951 with a 350-400whp goal on 93 octane, all with an outwardly stock appearing Porsche. No pillar pod, no obvious aftermarket exhaust, no stickers, stock rims, just a 951 which will kick the *** of anyone who revs at me.

Now I'm typing this pretty fast so there's probably a few typos I missed, my apologies.

J Chen

mrfixit,
I'm suggesting point 0.6 something or smaller for faster boost
not Edman. Anyway, I'm running a 0.82 AR hot housing.
Whaoo sounds bigger than what you had in mind right ?
No, in reality it's about the same size as a K26/6 hot
housing. Why, cause you have to keep in mind that the
AR ratios are specific for each model of turbo. In my
case the hot housing is base on a T25 model which is
listed by Garrett as a small frame turbo wherelse the
GT30 is listed as a medium frame turbo for whichever
hot housing they might use be it the GT or T3 series.
Hence, to get a grip on AR ratios, you should only
compare it base on the same model range.

J Chen

Hey Darklightning,
I myself cannot handle that kind of lag & I guess
alot of other guys as well. In your case you have the
added benefit of revving to 9000 rpm not to mention
that the head design being a 16v has better VE & a
much better combustion chamber design. I for one
would feel that you may not get the same results by
going GT35R for the 951. Hell, who knows, it's just
my point of view.

Corleone

Very good explanation! For an example I have a turbinewheel of 2,36/2,17" or 60/55 mm in a 0.61 A/R house. Its about the same in area as the KKK 8 hotside but with a lot moore of flowing and earlier spool.

J Chen

Thank you for the compliment Corleone.

Dark Lightning

Hrm, hadn't considered a fundamentally different VE. What's the base assumption for 2.5 liter 8 valve VE? The 4G63 was considered 100% with possible peaks up to 110% or more.