Red-Rx7

Hey all..

I finally got my turbo off the car, and am sending it back to Innovative Turbo for them to fix it (Justin has been great at Innovative thus far. Highly recomend!). My question is, should I make any changes; which doesn't effect the base or fitting area?

Some back ground:

Turbo is a T72 Dual Ballbearing, "Q" trim; mated to a 1.32 AR exhaust housing (4" downpipe attachment- with 4" exhaust all the way back).

The car dyno'd at 628.1 RWHP @ ~ 13.6 psi of boost; letting off at 6100 RPM due to a fuel leak (see dyno below). I firmly believe it would have made 630-640 rwhp if I would have continued up through 7500 RPM.



Below is the turbo compressor maps for my current turbo:



It is important to note that the purpose of the car is general fun. This would include streetability, road-racing, and occasional 1/4 racing (highway or track).

I typically would like to run no more than 15 PSI if possible; due to simple longevity of the car.

Would it be benificial to change to a T76 for this PSI range, or should I simply stay at the T72? Also, would the T76 compressor shell be much larger than the current one?

Thanks,
Mike

dvls-7

If it ain't broke don't fix it.....Thats a very impressive power curve. If memory is correct, theres not much benefit for steping up for the psi range you are running. Unless you plan on really taking that beast on top end runs, leave it how it is.

ZoomZoom

iTrader: (2)

I'D Like to see the torque. Eveyone forgets the 3 rotor also makes more TORQUE!

t-von

iTrader: (8)

I would like to see that as well. Maybe next time you dyno you can get some low boost numbers. I would love to see your power band at say 8psi.

Wargasm

Hmmmmm your T72 map doesn't agree with the Turbotnetics one...

Which is it?

The one you posted or this one:

http://64.225.76.178/catalog/compmaps/t72.html

Either way, it's not too far off.

Well, with the HP leveling off starting at around 5000 rpm, this is telling me that something in the system is blocking up the flow... Is the compressor too small? No, I don't think so. Is the exhaust too small? Yes, perhaps this is it.... Is the porting too small? Probably not.

I'm no expert, but in my opinion, I'd get a larger exhaust housing to free up the top end. Then again, you already have a LOT OF POWER and maybe more power doesn't translate into more fun because on the street there is just a limit of how much you can actually use.

If you were going to change anything, I'd increase the A/R of the turbine housing. I don't think you "need" to though if you already like the car the way it is.

680RWHP12A

leave the turbo you have now, thats a great turbo for what you want to do, and your motor will last forever.. what went wrong with your turbo? smokes?
iuse the innovative turbos and love them! only quirk is after awhile they smoke, easy fix for them

Red-Rx7

The turbo map came from Innovative, as for the turbo is an ITS. So I would imagine the map being different due to a different company.

I guess I could go to a 1.5 AR? That would be very large though. Currently, before the turbo died, I was able to get full boost (up to 22psi) by 2800 RPMs. It was instant. I like the curve too, but since this is my chance to make changes, it is why I asked.

Red-Rx7

The turbo started to smoke, and then died. I was driving on the highway and instantly had lag. Before, I was able to have full boost by 2800 rpms; then I couldn't build any boost until 5500 rpms. Pulled over, turbo would barely spin. Lots of shaft play too (enough to cause the blades to hit the housing).

Red-Rx7

After I get the turbo back, I will again go to the dyno. The lowest I can go is 10 PSI, for I have a 10 PSI spring in the wastegate.

spoolin93r1

what gear did you dyno in? the mph looks too high for 3rd and too low for 4th. i'm thinking my car hits 98-100mph at 8500 in 3rd and 150 in 4th at 8500

Wargasm

His dyno ended around 6100 rpm or so, that is why the mph seems too low to be 4th gear.

Marshall

In an ideal world, that compressor is way too small, you were at like 50% efficiency at 14 psi.

Red-Rx7

4th Gear dyno. It started to record in 3rd, hence the switch and drop. Then it stopped at 6100 RPM due to a fuel leak.

Red-Rx7

Thats what I was wondering. I was looking to be at 80%, or something close to it. Something that maximizes my usage and potential power. It runs great, but still.. I understand the logic of "dont fix it if it aint broke", but anyhow...

Red-Rx7

Yep.

Wargasm

Yeah if we're going off his posted compressor map (rather than the Garrett one), he's around 60% which isn't ideal I was basing my comments on the Garrett map which would put him around 72% which is a lot nicer.

Going to a T76 could be fun but it might sacrifice a little response. Seems to spool up mighty fast on the current setup so that might be just fine!

Marshall

How much air do you figure he's moving? I was thinking around 70 lbs/min through the power peak. In that case the turbonetics T-72 map does look pretty good (same as the garrett you mentioned probably). Then again its hard to argue with 600+ insta-spooling rwhp as long as EGTs and IATS are ok

GSB

Love to see a pic of the car in question there buddy sounds awesome.

Wargasm

I always assume that you take the rwhp on a Dynojet and divide by 10 get airflow; in this case he's moving around 64 lbs/minute of air. Possibly a little more if he was able to go past 6100. (but NOT more if his compressor is just out of breath already!)

Now here are some interesting things to look at... these are my 20B graphs on my site:

http://www.catenet.net/graph.php?car...1&SUBMIT=GRAPH

o Chito's car is using a T64, 10 PSI, uknown specs, stock block and makes mid 400s
o rx720bt's car is using T72, 14 PSI, P trim, 1.15 housing, street port and makes mid 400s
o Red-RX7's car is using T72, 14 PSI, Q trim, 1.32 housing, street port and makes mid 600s
o Ed Taylor's car is using 60-1, 12 PSI, uknown trim and A/R, and makes about 400 rwhp

Looking at all the graphs, especially the two T72 cars, the major difference that I think contributes to getting the 50% MORE horsepower is the opened up exhaust. Red-RX7 is using by far the biggest exhaust housing. He's got the biggest documented A/R at 1.32 and also the biggest confirmed wheel size at Q.

What I would take away from this examination of a small number of cars is that you can but a f'ing HUGE turbo on a 20B!

My question just looking at those 4 cars is this... "If they're using T72, 60-1, T64 which are all different compressors and they're running 10, 12, 14 PSI... how come 3 of the cars STILL look nearly identical on the dyno?".

I think the answer is in the exhaust side.

Now I'd feel horrible if Red-RX7 upgrades something and he doesn't like it just cuz of little old me, but if I was lucky enough to have Red's car (for sale? hehe), I'd try out a 1.52 Q trim and then hold on for dear life when it kicks in.

Then again as I've said before, a car that makes an easy 640 rwhp is a blast I'm sure. I'd like to see the power you put down at 10 PSI with the 1.52 housing!

Brian

twokrx7

iTrader: (1)

Has Innovative suggested their R trim wheel? Seems like it would be perfect for a low backpressure setup on the 3 rotor.

I've talked to them about it for my 2-rotor but they were unsure if spool would suffer. Been thinking of uping my P to a Q so we also discussed the R.

Red-Rx7

Good analysis.

Do you know if the other cars have their engine reworked as well? Different exhaust sleves, large ports, porting of the LIM/UIM?

I really do like the setup now, for it is pretty crazy. To be 100% honest, I have not really driven the car in the power band yet. For a while, I was driving the car before I put the RPM converter in it. So essentially, it would 75% less of the RPM band. If I were driving at 4000 RPM on the tac, the car was really at 3000 RPM. I never took the car above 5000 RPM on the tac, because of simply traction loss and it being quite scary. I figured the real RPM's were about 3700 - 4200 range. This is when the car really becomes alive, and would require you to have to back off.

I have since installed my RPM converter, and it seems to be 95% accurate, reading about 2% to 3% or so low. A few things often ponder into my head when driving the car, while the biggest one being how much emotional trouble the car has really caused me. This is something that I think about often driving it, which really prevents me from pushing the car to its real limits. To have it break down would be quite unreal at this point (read the upcoming RXTuner magazine for an example of the emotional story).

I doubt if I would make any changes at this point anyways, but wanted to get some feed back from others. When ever you do something, 10 people always tell you to do it another way. The setup works great as is. Nothing but instant response, and huge power. When I get it back, I will take a video of the boost guage, for that is just mind blowing; with regards to the gas peddle. For example in 5th gear, I could be cruising at 45 - 50 mph. The RPMs would be pretty low, and I would just tap the gas. When I did this, the boost gauge would seem to be attached to my foot. The instant second I touched the gas, the needle moved accordingly.

Right now, I have 275's on the car for the rear tires. I don't know if any tire could really provide the traction I am looking for, unless it was a warm ET slicks or something. The trick is to modulate the throttle, and I haven't really learned it yet for my driving experience has been limited to about 4200 real RPMs. I can't stay in it past that.

Red-Rx7

You can see the car in this picture (sorry for it being so big):

Red-Rx7

BTWl; I have a video of the dyno run too. If anyone knows how to compress it; or can tell me how, I will host it.

GSB

Thanks for the pic bro.

Red-Rx7

Here is the dyno vid (about 5meg):

http://home.comcast.net/~mhaun5/rx7/RedRx714PSI.wmv