BigBadChris and the little turbo RX8
05-28-2015, 03:13 PM
#26
Yes sir, I know that a Precision is not a Garrett. I know that Scott is currently a Precision dealer. I know that for a long time, Precision sold Garretts with upgraded internals. I know that they then turned around and marketed their upgrades, which irritated Garrett, leading them to be cut off as reseller, and they (Precision) had to market their own stuff. I also know that while these kits were in production, Scott had a delay in production because of a hold up with the supplier....Garrett. What I do not know, since I have not seen the unit, is if it is a Garrett or a Precision.
Since you are the guru, please, educate me. Save me from my ignorance.
Since you are the guru, please, educate me. Save me from my ignorance.
05-28-2015, 03:18 PM
#27
Driving my unreliable rx8
I think your biggest issure will be the boost profile.
That big of a turbo would be overkill on a manual at 9000 rpm. When you shift you fall to 6000-6500 depending on shift points. The turbo will stay spooled well.
On a car with a 7500 rpm redline. you will probably drop to 4500 RPM or so when you shift. At 4.5K rpm the turbo will not be spooling hard. Just as the turbo start spooling up good again it'll be time to shift.
That big of a turbo would be overkill on a manual at 9000 rpm. When you shift you fall to 6000-6500 depending on shift points. The turbo will stay spooled well.
On a car with a 7500 rpm redline. you will probably drop to 4500 RPM or so when you shift. At 4.5K rpm the turbo will not be spooling hard. Just as the turbo start spooling up good again it'll be time to shift.
Last edited by logalinipoo; 05-28-2015 at 03:23 PM. Reason: I overestimated the rpm drop a little. I don't know what it is for an auto at all.
05-28-2015, 03:24 PM
#28
@ logalinipoo
Thank you for your quick, simple reply.
Scott has offered to swap out the hot side to a smaller inlet, to help it spool a bit quicker. Will it fix things completely? No. Will it help? Yes. Its a big *** turbo, I have not been shy about that. Correct me if Im wrong, but I just use boost to accelerate. Once Im up to speed, Im good. In a 4 speed car, you don't need to shift that often before you're over the speed limit. All I want is quicker acceleration....Zoom Zoom.
Thank you for your quick, simple reply.
Scott has offered to swap out the hot side to a smaller inlet, to help it spool a bit quicker. Will it fix things completely? No. Will it help? Yes. Its a big *** turbo, I have not been shy about that. Correct me if Im wrong, but I just use boost to accelerate. Once Im up to speed, Im good. In a 4 speed car, you don't need to shift that often before you're over the speed limit. All I want is quicker acceleration....Zoom Zoom.
Last edited by BigBadChris; 05-28-2015 at 03:35 PM.
05-28-2015, 03:37 PM
#29
Driving my unreliable rx8
The smaler hotside will help. IT will vary with every application. My ct2-6065 will only produce 3 psi or so from 3000 to 3500 rpm. Then it will build up to 6 psi (my current setting) almost imediately. That's with a 0.62AR hot side.
I am just guessing , but you won't start developing boost until over 4K, and probably not signifigant levels until 4500. So you have 3000 rpm of boost at most. Where as on a manual with a smaller turbo it will give me 5500 rpm of boost.
Go for a drive and record the rpm it shifts at and what it drops to. Then you'll see how small of a rnage you might actually have for your turbo to operate in.
I am just guessing , but you won't start developing boost until over 4K, and probably not signifigant levels until 4500. So you have 3000 rpm of boost at most. Where as on a manual with a smaller turbo it will give me 5500 rpm of boost.
Go for a drive and record the rpm it shifts at and what it drops to. Then you'll see how small of a rnage you might actually have for your turbo to operate in.
05-28-2015, 03:51 PM
#30
Good advice, and thank for your the anecdote about your turbo and its A/R. I believe I am looking at a .67 impeller cover. I am sure I could procure an even smaller one if necessary. You're right, I do not have as much rpm to play with, but I am usually speeding by the time I am out of second gear as it is.
I will record shift points and ranges tonight. I also planned on raising the rev limit with the AP. Certainly not raising it to 6 port levels, but it is my understanding that it can go to 8 without issue.
I will record shift points and ranges tonight. I also planned on raising the rev limit with the AP. Certainly not raising it to 6 port levels, but it is my understanding that it can go to 8 without issue.
05-28-2015, 03:57 PM
#31
Driving my unreliable rx8
The fact your speeding by then is exactly why this setup will really suck for you. The turbo will never really start spinning good. The thing I like most about min is. While cursing down the highway. I press the pedal and hear it spool up and pull without even shifting.
I wouldn't worry about it overall too much. If you already have it and it is used. Try it. it's not like you'll reduce the sale price by trying it. If it doesn't work, go with smaller.
I wouldn't worry about it overall too much. If you already have it and it is used. Try it. it's not like you'll reduce the sale price by trying it. If it doesn't work, go with smaller.
05-28-2015, 03:58 PM
#32
SARX Legend
iTrader: (46)
What will you be using for the tuning? The Microwreck? I don't recall the intake setup on the Type 3 but my only design gripe with the kit is the wastegate placement, it is horrible IMO.
05-28-2015, 04:03 PM
#33
The turbo should spin real good in first, and then I'm in second and where I need to be. The dyno sheets I have seen show the turbo topping out on power right around 7500 rpm, which happens to be my shift point.
I just want some seat of the pants power. You're right, if it doesn't work, ill sell the turbo and buy a smaller one. Everything else will be usable. Intake, intercooler, and all the cooling mods I have done.
@ 9k
We have discussed the Interceptor and the Cobb AP. I think the Cobb has more functionality and is more serviceable, but I leave that up to the tuner. I have neither the inclination nor the time to learn to tune myself. As far as I know, the waste gate has been plumbed to recirculate into the down pipe.
I just want some seat of the pants power. You're right, if it doesn't work, ill sell the turbo and buy a smaller one. Everything else will be usable. Intake, intercooler, and all the cooling mods I have done.
@ 9k
We have discussed the Interceptor and the Cobb AP. I think the Cobb has more functionality and is more serviceable, but I leave that up to the tuner. I have neither the inclination nor the time to learn to tune myself. As far as I know, the waste gate has been plumbed to recirculate into the down pipe.
05-28-2015, 04:15 PM
#34
SARX Legend
iTrader: (46)
And is he a Cobb protuner? I doubt it. And yes it is plumbed, it is the placement that bugs me, it should be as close to the turbine inlet as possible.
As for that turbo and boost, drivability, etc. You will learn. Unless you happen to live near the autobahn.
As for that turbo and boost, drivability, etc. You will learn. Unless you happen to live near the autobahn.
05-28-2015, 04:25 PM
#35
I have not seen the kit in person, so I cannot comment about the waste gate itself.
As for his credentials for the AP, I didn't ask. I am going to drop this subject because it is talking about the person, not the build. It is my preference that the car be tuned via the Cobb system. It is more recent, has more functionality, and is supported by many more tuners than the Interceptor, which is a proprietary product. I freely admit it is not a good idea to have a car that needs to be trucked across state lines if there is a problem with my tune.
As for drivability, yes, I am going to learn quite a bit. The stock car is grossly lacking in some areas. This is going to change the car, dramatically. No, I do not live near the autobahn, but I have plenty of highway onramps and flying overpasses.
As for his credentials for the AP, I didn't ask. I am going to drop this subject because it is talking about the person, not the build. It is my preference that the car be tuned via the Cobb system. It is more recent, has more functionality, and is supported by many more tuners than the Interceptor, which is a proprietary product. I freely admit it is not a good idea to have a car that needs to be trucked across state lines if there is a problem with my tune.
As for drivability, yes, I am going to learn quite a bit. The stock car is grossly lacking in some areas. This is going to change the car, dramatically. No, I do not live near the autobahn, but I have plenty of highway onramps and flying overpasses.
05-28-2015, 05:51 PM
#36
SARX Legend
iTrader: (46)
Well tuning is key, I cannot stress that enough. Many over look this or waste time with tuners who say they can do it when in reality they can't because they just don't have the experience with Turbo RX-8's. So learn what you can about that, trust me.
And trust me, once turbo you won't spend as much time at high RPM's as you think,
And trust me, once turbo you won't spend as much time at high RPM's as you think,
05-28-2015, 06:02 PM
#37
I agree with you 100% about the tune. There is a local rotary shop here in Dallas, but I could not do the work there because they could not tune a turbo car. No experience with turbo rx8. They have installed greddy kits and Emanage, but their dyno is not ready yet so no tune for me. I could have installed it and done internet tune, but I wanted it all to be done at once. Build, test it, tune it, fix it if need be.
05-28-2015, 07:54 PM
#40
Thought the thread needed some levity ! heh .
Getting back to the turbo ................ made for 935 piston whp or 660ish rotary whp . You are talking maybe 260whp on your AT . It's just a money wasting exercise to even try it IMO.Even with a 0.63 housing the spoolup will be poor .
I strongly suggest you sell the turbo ... you should get reasonable money for it if in reasonable condition .
Then get something like a 5558 . Not only will it make the same power (based on the constraints of your drivetrain) , but it will spool really well and improve the driving dynamics tenfold !
Getting back to the turbo ................ made for 935 piston whp or 660ish rotary whp . You are talking maybe 260whp on your AT . It's just a money wasting exercise to even try it IMO.Even with a 0.63 housing the spoolup will be poor .
I strongly suggest you sell the turbo ... you should get reasonable money for it if in reasonable condition .
Then get something like a 5558 . Not only will it make the same power (based on the constraints of your drivetrain) , but it will spool really well and improve the driving dynamics tenfold !
05-28-2015, 08:25 PM
#41
SARX Legend
iTrader: (46)
I agree with you 100% about the tune. There is a local rotary shop here in Dallas, but I could not do the work there because they could not tune a turbo car. No experience with turbo rx8. They have installed greddy kits and Emanage, but their dyno is not ready yet so no tune for me. I could have installed it and done internet tune, but I wanted it all to be done at once. Build, test it, tune it, fix it if need be.
He is a Cobb pro tuner and an adaptronic supplier/tuner. He can also tune a bunch of other platforms, everything from stock cars to diesel trucks. But rotaries are where his heart is at. he is also an excellent fabricator.
PRT Performance | Lewisville Performance Shop | Dallas Auto Services | Dyno Tuning
Last edited by 9krpmrx8; 05-28-2015 at 08:34 PM.
05-28-2015, 11:45 PM
#43
I think so many people don't understand how good a fast spooling turbo is for street work . IMO fitting a turbo to a street car is about the fun you can have driving it ... which means midrange is all important . Having a big *** turbo is way overrated !
05-29-2015, 10:13 AM
#44
SARX Legend
iTrader: (46)
I agree, the problem is people just get so caught up on peak HP figures that it skews their view of things. That happens in every platform, people just go for HP figures regardless of whether they can put than power down or not.
Last edited by 9krpmrx8; 05-29-2015 at 10:20 AM.
05-31-2015, 07:51 PM
#45
Chris buys a big stinking turbo, he's a fool and it must be sold. Brettus buys a big turbo (62mm not 67mm) and its "time to get serious". How strange, considering all rx8s behave the same at low rpm, because the variable duct isn't open and your aux ports have not kicked in yet.
Just calling it like I see it....
Just calling it like I see it....
05-31-2015, 08:27 PM
#46
Chris buys a big stinking turbo, he's a fool and it must be sold. Brettus buys a big turbo (62mm not 67mm) and its "time to get serious". How strange, considering all rx8s behave the same at low rpm, because the variable duct isn't open and your aux ports have not kicked in yet.
Just calling it like I see it....
Just calling it like I see it....
I can see how you might take it that way, however there is a lot you are not considering .* You have an AT , the AT itself is a limiting factor in how much power you can make.
* You have a 4 port , also a limiting factor .Although this wont affect spoolup , a 4 port is effectively a smaller engine passed the 6000rpm mark.
* You are fitting a top mount turbo , so spoolup will already be compromised by this design . A bigger turbo exacerbates this design compromise. I would guess with your setup that full spool will be between 4500 and 5000 , you won't appreciate how bad that is until you drive a car with a resposive turbo.
*Yours is 67mm mine is 62 ........ quite a bit bigger in real terms.
*I actually plan to utilise the full flow my turbo has to offer , you don't ( and can't).
*I have experience with boosting at the limit and tuning/wrenching/trouble shooting .... you don't.
*I really wouldn't be too concerned if I blew my engine/transmission up , you ....???
Last edited by Brettus; 05-31-2015 at 08:46 PM.
05-31-2015, 09:05 PM
#47
I can see how you might take it that way, however there is a lot you are not considering .* You have an AT , the AT itself is a limiting factor in how much power you can make.
* You have a 4 port , also a limiting factor .Although this wont affect spoolup , a 4 port is effectively a smaller engine passed the 6000rpm mark.
* You are fitting a top mount turbo , so spoolup will already be compromised by this design . A bigger turbo exacerbates this design compromise. I would guess with your setup that full spool will be between 4500 and 5000 , you won't appreciate how bad that is until you drive a car with a resposive turbo.
*Yours is 67mm mine is 62 ........ quite a bit bigger in real terms.
*I actually plan to utilise the full flow my turbo has to offer , you don't ( and can't).
*I have experience with boosting at the limit and tuning/wrenching/trouble shooting .... you don't.
*I really wouldn't be too concerned if I blew my engine/transmission up , you ....???
Yes, I can't rev like you do, but if full spool happens BELOW 6k (when the six ports kick in), aren't we equals until 6k?
The dyno I saw of this kit shows boost happening as low as 3500, but Max power is at 7500. Maybe I'm being naive here, but isn't any boost better than where I am now?
Yes, the manifold is in a much different spot. I trust my builder, he wouldn't have sold the kit if it didn't work. We will see what happens when my car hits the dyno. Honestly tho, aren't we talking about the difference of a few cubic feet between my manifold and yours?
Also, I think I have one huge advantage that the stick shifting crowd does not. My throttle position stays when I shift gears. I can stand on the brakes, make boost, and let go of the brake. When you guys shift gears, you have to let go of the throttle, even for a split second.
I have a local rotary mechanic who has been in the business a long time. He has built and repaired rx7 and rx8 engines. The only reason I am not working with him is that he was not familiar with this kit. He wanted to charge a lot more to install it because of the labor time. This person is also close to my builder. I am confident that anything that pops up, they can fix.
I said in my first post I have budgeted for a rebuild. I have an ideal price for this project, but only a fool adds boost to a car without knowing it could literally blow up in his face.
Last edited by BigBadChris; 05-31-2015 at 10:20 PM. Reason: Edited for clarity
05-31-2015, 09:22 PM
#48
I'm not talking about boost "as low as" 3500 ....I'm talking about fully spooled up by 3500 . Until you have driven cars with a responsive turbo you wont appreciate how much more fun to drive they really are . BTW ... it's not only at low rpm that it matters .
There are a couple of guys here with top mounts (and similar sized turbos) that I have raced from a rolling start ... It really is a joke how much quicker my (low mount) car is than theirs .
There are a couple of guys here with top mounts (and similar sized turbos) that I have raced from a rolling start ... It really is a joke how much quicker my (low mount) car is than theirs .
Last edited by Brettus; 05-31-2015 at 09:24 PM.