Page 8 approves.

8/17/2009 6:07:10 AM

i got the hose, i'll probably install it this week. I haven't driven the car in a while now because I've been out of town etc

8/17/2009 1:08:04 PM

took this thing out last night when it was in the 70s outside. this turbo is really waking up with the colder temps.

8/30/2009 3:49:49 PM

nice! How is the fuel consumption currently?

8/30/2009 4:57:11 PM

i would enjoy seeing this car in person while it flies by me boosting the shit outta the lil wankel's. or just a youtube vid would suite me just fine.

8/30/2009 6:16:07 PM

Quote :

"nice! How is the fuel consumption currently?"

no worse than you would get out of a mostly stock car really. 16-17 in the city if you are easier on it, 12-13 if you have fun, and low 20's on the highway.

Quote :

"i would enjoy seeing this car in person while it flies by me boosting the shit outta the lil wankel's. or just a youtube vid would suite me just fine."

I've been meaning to make at least a quick video inside the cockpit, but it just started raining so it may take a while for that to happen. I've gotta remember to get my camera and I've got to get somebody else to hold it while I drive.

8/31/2009 12:58:52 AM

DIBS ON CAMERA MAN POSITION.

8/31/2009 7:29:09 AM

so i finally found a proper compressor map for my turbo

9/8/2009 1:26:13 AM

i need to c the vid!

9/8/2009 10:16:12 AM

I haven't made a video yet. I had a clutch hydraulics failure the other day fucking 80s car. it might be a little while before it runs again, I want to replace both master and slave cylinders at the same time.

9/8/2009 5:10:01 PM

that is one badass turbo map

9/8/2009 5:17:46 PM

Man that thing flows a ton. It seems like an incredible laggy way to get 400HP.

I'm prepared to be pwned by an arghx 900 page response.

9/8/2009 6:49:06 PM

transient response isn't bad with the twin scroll manifold; it will get into positive pressure easily enough. full boost is around 4500 rpm and the valve timing equivalent is optimized for top end. the powerband is 4000-8000, with the meat of it from 4500-7500. since i have an 87-88, the gearing is very aggressive and closely spaced compared to all the other turbo models. so it stays in its powerband all the time when you are doing WOT driving. when I top 4th gear around 120mph, 5th gear will be at about 5000rpm.

so the turbo isn't hampering WOT performance much; it is matched to the porting etc. That being said, from a driveability perspective I do miss the instant response that a stock car has. You do have to wait for the torque some.

Remember that rotary engines have extremely hot exhaust (I see around 1650-1700 F preturbo on the rear rotor exhaust manifold runner). the extra energy means that the 2 rotors will spool a turbo like a 6 cylinder and the 3 rotors will spool a turbo like a good sized v8. It's not uncommon for 3 rotors with appropriately sized turbos to make 500+rwhp at less than 1 bar of boost

[Edited on September 8, 2009 at 8:27 PM. Reason : you rode in it Quinn, it's not a 1.8T but it's not a Supra-style on/off switch powerband either]

9/8/2009 8:20:26 PM

now here's the 50 pager.

Compare these two compressor maps. Both are nominally 67mm turbos. The first one I just posted. It is the Garrett T67/T04R/T04Z , with similar models from Precision and HKS. this is a 67mm inducer, 84 mm exducer. 67^2/84^2 = 63 trim or so.



Now check out this other "67mm" turbo: the GT4094, 67mm inducer 94mm exducer, 52 trim.



notice that this is a 52 trim turbo. The trim value is an aspect ratio between the inducer (which draws the air into the turbo) and the exducer (which hurls the air through the outlet). Turbos with a smaller trim value have, relatively speaking, larger exducers. They tend to be more efficient at higher boost. Notice how far the efficiency extends in the vertical axis direction?

Now look back at my "67mm" turbo. It is a 63 trim because of the smaller exducer. Even though the efficiency numbers aren't the same, notice how the efficiency extends further along the horizontal axis? There are fewer isobars--it is a less steep "hill" of efficiency if you were thinking in terms of a topographic map. This is from the larger inducer (relatively speaking). Higher trims then are not necessarily "better" than smaller trims, often just different. 4 cylinder spark ignited engines and a lot of diesel engines tend to do best with higher pressure ratios, so they often have low trim values. TD04 and TD05 family mitsu turbos are like this, and so are Holset HX series turbos. Both tend to have trim ratings in the 40ish range.

Where the confusion arises IMO is that a lot of 4 cylinders utilize the T04E family of T3/T4 hybrids. All the T04E wheels have the same size exducer, and then the higher trim turbos have a larger inducer which results in more airflow. So people get into this habit of thinking that higher trim values are better. This is further exacerbated by a portion of domestic owners who like to brag about how many mm or big of a trim number their turbo has. As I've demonstrated here, the term "x mm turbo" and "y trim turbo" is not so straightforward to interpret without further information.

also, due to some efficiencies in the shape of the rotary combustion chamber, more airflow is required to achieve the same level of horsepower. if every 10 lb/min on a piston engine yields 10ish whp, you might get 8 on a rotary. So my engine needs a bigger compressor wheel to make the same power as a 4 cylinder, and on the exhaust side it needs a large wheel and turbine housing to keep backpressure down.

The stock turbo on my 2nd gen has the equivalent of a 1.00 A/R turbine housing on it, with a T3 stage 2 turbine wheel and a compressor wheel closest to the T3 50 trim compressorwheel. That's relatively large for a stock internally wastegated turbo, but yet that turbo maxes out at maybe 250 to the wheels.

[Edited on September 8, 2009 at 8:53 PM. Reason : .]

9/8/2009 8:41:12 PM

one item to clarify: you mention "twin scroll"... elaborate

9/8/2009 9:19:56 PM

Quote :

"if every 10 lb/min on a piston engine yields 10ish whp, you might get 8 on a rotary."

Ah. Gotcha. Helps explain most of it.



Your car didnt appear too laggy but looking at the compressor maps it looks like there would have been a turbo with a quicker spool that netted you a similiar HP. I'm one to work with what I've got / can get cheap because I am a cheap ass so I def. understand that approach angle as well.


Thanks for the information by the way. I'm holding out for a good deal on a GT30R

9/8/2009 9:43:38 PM

I got a good deal on this turbo. I traded parts I was going to get rid of anyway for it. It cost me almost nothing out of pocket. It is also common on this application--Supras and Rx-7's run variants of these all the time. And when I bought it, I thought I was going to be running 25psi all the time with methanol injection. I don't have the money for that right now. This turbo leaves me room to grow should I ever decide/afford to do so.

Quote :

"one item to clarify: you mention "twin scroll"... elaborate"

this can mean a lot of things, but in most cases it just means a divided inlet with a matching divided manifold which separates exhaust pulses from one bank or set of cylinders. It's like the turbine housing and inlet on a Ram HX35. The 87-88 Rx-7's had a more complicated system than that, where one of the passageways was smaller and one was bigger. A flapper kept the larger passageway closed until about 3000rpm.

Evo has a divided/twin scroll design

Evo 9



Evo 8



[Edited on September 9, 2009 at 12:01 AM. Reason : .]

9/8/2009 11:58:43 PM

I'm brocotting this thread till a vid of thsi car pops up. kthx

9/9/2009 12:56:51 AM

^^A divided housing with a matching manifold is understood, but why would an equally divided manifold be sent to an unequally shaped housing?

9/9/2009 8:37:58 AM

it was an undivided manifold mating to a divided housing with unequal sized ports. The small one was always open and then the larger one opened over something like 2800 rpm. Mazda switched to the divided manifold/divided housing setup in 89, with an internal wastegate that bled off both runners. it was simpler.

9/9/2009 1:56:07 PM

AHA! Undivided manifold! clarity!



- Check out the new Ford 6.7L diesel "Scorpion" engine - Single turbo with two compressor stages on a common shaft (they call it "SST" or some shit)






[Edited on September 9, 2009 at 2:30 PM. Reason : -]

9/9/2009 2:26:26 PM

I ordered the clutch hydraulics (master and slave, already have a stainless hose for the non-hardline part). I managed to find the OEM parts at prices that are very close to autozone/Advance stuff. I'm kinda pissed though, I really wanted to drive this thing this weekend. It's really nice out. and when the windows are down you can't hear the interior rattling so much

9/11/2009 4:48:09 PM

I fixed the clutch a while back and redid the turbo oil drain line because it had a leak. I think my next winter project will be installing a bump stop for the differential:



The differential mount is known to break from the vibration of hard launches and this should reduce the chance of this occurring. I have to drill a hole inside the car and then use fender washers to preload the bump stop against the diff.

10/7/2009 8:09:30 AM

so basically like a pinion snubber on a solid axle car...?

10/8/2009 12:08:06 AM

yeah pretty much. i'll probably make it a winter project when i'm bored. there's no pressing need to do this

10/9/2009 12:28:28 AM

are you driving the damn thing yet?

10/14/2009 9:19:11 AM

I just put about 100 miles on it in the past week and a half.

10/14/2009 12:58:32 PM

keep that kinda miles up and you'll be rebuilding it again next month

10/15/2009 7:33:26 AM

this thing needs bigger wheels and tires. At these temperatures it's spinning from a 2nd gear roll with 1/4 throttle

12/21/2009 1:02:12 PM

drop the money on a haltec/motec and wheel slip sensors. you could build your own traction control.

12/21/2009 4:13:48 PM

hey i know a guy who works with motec... its his job to figure out how to rig up abs and traction control through an older car.

12/28/2009 11:47:38 PM

I think I'm just going to get tires that can actually grip. I have bald 225 Sumitomos right now. I am going to see if I can fit 275's in the back with 17x10 wheels

12/29/2009 10:11:08 AM

225 is a joke ! I think lance runs that on his bicycles.

12/29/2009 11:22:20 AM

alright Quinn I changed the bumper out. it doesn't look so ricer now.

2/23/2010 9:52:11 AM

Video time!

http://www.youtube.com/watch?v=9DR5pPwGOkk

1st and 2nd gear pull coming off a light. I am not too hard on it in 1st in order to keep traction--maybe 1/2 throttle? According to the Power FC I hit 8200rpm in 2nd, so that's about 70mph.

[Edited on April 22, 2010 at 9:51 PM. Reason : .]

4/22/2010 9:48:54 PM

She'll move. I still swear by black intercooler / charge pipes.

Every ricer has their own style i suppose.

4/23/2010 11:16:26 AM

how high does it rev? my rb goes to 7500. i want to change out cams springs retainers so i can rev to like 9

4/23/2010 3:08:53 PM

man that looks awesome !! i like the idea of coated pipes but painting an intercooler is a bad idea.
black holds more heat and the boundry condition of having paint on it makes it less effective.

i know i know radiators are black blah blah blah... they also keep your car @ 185- 200 which with an intercooler it should be as cool as possible.

consider my 2¢

^ which RB do you have and what is it in?


[Edited on April 23, 2010 at 3:47 PM. Reason : .]

4/23/2010 3:47:16 PM

It doesnt matter!!!!!!!!11 Paint touchs what 10% of the surface very lightly. I've done it on an ebay-cooler and put down half ass decent numbers. At least the front of the car doesnt scream "HEY LOOK AT ME" .

Ray's a bit more of a professional when it comes to builds though .

4/23/2010 3:55:42 PM

meh, my intercooler was powdercoated. still put down some good numbers.

4/23/2010 4:10:37 PM

^ what turbo are you running?
What kind of hp are yall running and what size is your core?

cause honestly if your running 250hp on a core big enough for 500 then paint the shit out of it...

4/23/2010 6:12:08 PM

Quote :

"how high does it rev? my rb goes to 7500. i want to change out cams springs retainers so i can rev to like 9"

8500 is the highest I am comfortable taking it because the 87-88 rotating assembly isn't balanced for much higher than that. In that video I hit 8200 in 2nd (tach is a little off but I can see what the ECU is reading). Most of the time I take it to 8000 at most. I still haven't put it on the dyno but based on the shape of my fuel curve I can see the power is leveling out by 7500 and falling by 8000. I would probably need a 1.31 A/R turbine housing (currently have a 1.00) to make power up to 9000rpm, which I'm not willing to do due to a loss of part throttle response around town. The turbo had a 1.31 turbine housing on it when I bought it but I swapped out for the 1.00 before I even bolted up the turbo.

There is no point in revving your RB to 9000 unless you are making power there or you are in some kind of competitive scenario that is best served by revving it that high despite a lack of power. If you really do want to make power up to 9000rpm, you are going to need a high flowing compressor wheel and a big turbine housing, which will likely result in a loss of low end response. Then the gearing becomes a factor. On my transmission (stock 87 turbo model) you can see that as I shift into 2nd gear I am already over 5000rpm so I never drop out of the powerband.

4/24/2010 12:21:21 AM

what size tires are you running out back and how much of a problem is wheel spin?

4/30/2010 4:22:08 PM

1. 225 Sumitomos, almost 6 years old from my old nonturbo rx-7

2. bad when it's colder than 50 degrees F outside

money is very bad right now to be honest, I can barely afford insurance and some gas for this thing

[Edited on May 1, 2010 at 11:45 AM. Reason : in 2nd gear, sideways from a roll at 1/4 throttle when it's cold outside]

5/1/2010 11:41:57 AM

lol just getting ideas not criticizing just wondering i may be working on a project where tire size is a factor... from what i read 225s without rolling the fenders, 245s with.... EEK! i figure the 400whp is attainable but on 225s it would be scary of course i haven't driven anything with r compounds on the street so i don't know how big of a difference they would make.

5/3/2010 12:01:06 AM

It very much depends on the final torque curve of the engine. A more responsive setup is worse for traction. My setup is kind of dead under 4500rpm or so, at least in terms of torque. I'm sure if I had a smaller hotside (like a .63 divided or something) the car would be undriveable.

5/3/2010 10:55:39 AM

m/t et street radials [/thread]

5/3/2010 2:55:57 PM

Any news on the arghx-7?

4/18/2011 12:38:55 PM

I got new tires a couple weeks ago. I looked at ET streets for the rear, but the only sizes I could use would noticeably throw off my speedometer. That may seem trivial but I have had that happen before due to tire size and the speedometer thing drove me absolutely nuts. The tires I bought are Dunlop DZ-101's in the 225/45/17 size I had before (wheels are 7 inches wide, from my old non turbo Rx-7). They are somewhat low end Z rated summer performance tires but cost was a big issue here. I was going to get Falken Azenis but the prices just shot up on them. Tire prices in general are increasing.

For what I paid, I am happy with the Dunlops compared to dry rotting Sumitomos. Handling and steering are much more solid now and the twitchy understeer/oversteer characteristic is much improved. In a straight line they are hooking better than the old tires once they are warmed up. I have been getting traction in 2nd gear lately, although the weather has warmed up which helps.

4/18/2011 12:57:28 PM

Yeah its pretty cool being able to calibrate the speedo via OBDII

Can the AP do that too (i'm assuming it can since cobb hired the guy who wrote romraider)

4/18/2011 1:24:05 PM